Sample records for aerosol extinction profile

  1. The Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP) Version 1 aerosol extinction retrieval algorithm: theoretical basis

    NASA Astrophysics Data System (ADS)

    Loughman, Robert; Bhartia, Pawan K.; Chen, Zhong; Xu, Philippe; Nyaku, Ernest; Taha, Ghassan

    2018-05-01

    The theoretical basis of the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler (LP) Version 1 aerosol extinction retrieval algorithm is presented. The algorithm uses an assumed bimodal lognormal aerosol size distribution to retrieve aerosol extinction profiles at 675 nm from OMPS LP radiance measurements. A first-guess aerosol extinction profile is updated by iteration using the Chahine nonlinear relaxation method, based on comparisons between the measured radiance profile at 675 nm and the radiance profile calculated by the Gauss-Seidel limb-scattering (GSLS) radiative transfer model for a spherical-shell atmosphere. This algorithm is discussed in the context of previous limb-scattering aerosol extinction retrieval algorithms, and the most significant error sources are enumerated. The retrieval algorithm is limited primarily by uncertainty about the aerosol phase function. Horizontal variations in aerosol extinction, which violate the spherical-shell atmosphere assumed in the version 1 algorithm, may also limit the quality of the retrieved aerosol extinction profiles significantly.

  2. Aerosol Extinction Profile Mapping with Lognormal Distribution Based on MPL Data

    NASA Astrophysics Data System (ADS)

    Lin, T. H.; Lee, T. T.; Chang, K. E.; Lien, W. H.; Liu, G. R.; Liu, C. Y.

    2017-12-01

    This study intends to challenge the profile mapping of aerosol vertical distribution by mathematical function. With the similarity in distribution pattern, lognormal distribution is examined for mapping the aerosol extinction profile based on MPL (Micro Pulse LiDAR) in situ measurements. The variables of lognormal distribution are log mean (μ) and log standard deviation (σ), which will be correlated with the parameters of aerosol optical depht (AOD) and planetary boundary layer height (PBLH) associated with the altitude of extinction peak (Mode) defined in this study. On the base of 10 years MPL data with single peak, the mapping results showed that the mean error of Mode and σ retrievals are 16.1% and 25.3%, respectively. The mean error of σ retrieval can be reduced to 16.5% under the cases of larger distance between PBLH and Mode. The proposed method is further applied to MODIS AOD product in mapping extinction profile for the retrieval of PM2.5 in terms of satellite observations. The results indicated well agreement between retrievals and ground measurements when aerosols under 525 meters are well-mixed. The feasibility of proposed method to satellite remote sensing is also suggested by the case study. Keyword: Aerosol extinction profile, Lognormal distribution, MPL, Planetary boundary layer height (PBLH), Aerosol optical depth (AOD), Mode

  3. In Situ Aerosol Profile Measurements and Comparisons with SAGE 3 Aerosol Extinction and Surface Area Profiles at 68 deg North

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Under funding from this proposal three in situ profile measurements of stratospheric sulfate aerosol and ozone were completed from balloon-borne platforms. The measured quantities are aerosol size resolved number concentration and ozone. The one derived product is aerosol size distribution, from which aerosol moments, such as surface area, volume, and extinction can be calculated for comparison with SAGE III measurements and SAGE III derived products, such as surface area. The analysis of these profiles and comparison with SAGE III extinction measurements and SAGE III derived surface areas are provided in Yongxiao (2005), which comprised the research thesis component of Mr. Jian Yongxiao's M.S. degree in Atmospheric Science at the University of Wyoming. In addition analysis continues on using principal component analysis (PCA) to derive aerosol surface area from the 9 wavelength extinction measurements available from SAGE III. Ths paper will present PCA components to calculate surface area from SAGE III measurements and compare these derived surface areas with those available directly from in situ size distribution measurements, as well as surface areas which would be derived from PCA and Thomason's algorithm applied to the four wavelength SAGE II extinction measurements.

  4. Retrieval method of aerosol extinction coefficient profile by an integral lidar system and case study

    NASA Astrophysics Data System (ADS)

    Shan, Huihui; Zhang, Hui; Liu, Junjian; Wang, Shenhao; Ma, Xiaomin; Zhang, Lianqing; Liu, Dong; Xie, Chenbo; Tao, Zongming

    2018-02-01

    Aerosol extinction coefficient profile is an essential parameter for atmospheric radiation model. But it is difficult to get the full aerosol extinction profile from the ground to the tropopause especially in near ground precisely using backscattering lidar. A combined measurement of side-scattering, backscattering and Raman-scattering lidar is proposed to retrieve the aerosol extinction coefficient profile from the surface to the tropopause which covered a dynamic range of 5 orders. The side-scattering technique solves the dead zone and the overlap problem caused by the traditional lidar in the near range. Using the Raman-scattering the aerosol lidar ratio (extinction to backscatter ratio) can be obtained. The cases studies in this paper show the proposed method is reasonable and feasible.

  5. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Kittaka, C.; Vaughn, M. A.; Remer, L. A.

    2010-01-01

    We derive aerosol extinction profiles from airborne and space-based lidar backscatter signals by constraining the retrieval with column aerosol optical thickness (AOT), with no need to rely on assumptions about aerosol type or lidar ratio. The backscatter data were acquired by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The HSRL also simultaneously measures aerosol extinction coefficients independently using the high spectral resolution lidar technique, thereby providing an ideal data set for evaluating the retrieval. We retrieve aerosol extinction profiles from both HSRL and CALIOP attenuated backscatter data constrained with HSRL, Moderate-Resolution Imaging Spectroradiometer (MODIS), and Multiangle Imaging Spectroradiometer column AOT. The resulting profiles are compared with the aerosol extinction measured by HSRL. Retrievals are limited to cases where the column aerosol thickness is greater than 0.2 over land and 0.15 over water. In the case of large AOT, the results using the Aqua MODIS constraint over water are poorer than Aqua MODIS over land or Terra MODIS. The poorer results relate to an apparent bias in Aqua MODIS AOT over water observed in August 2007. This apparent bias is still under investigation. Finally, aerosol extinction coefficients are derived from CALIPSO backscatter data using AOT from Aqua MODIS for 28 profiles over land and 9 over water. They agree with coincident measurements by the airborne HSRL to within +/-0.016/km +/- 20% for at least two-thirds of land points and within +/-0.028/km +/- 20% for at least two-thirds of ocean points.

  6. How well can we Measure the Vertical Profile of Tropospheric Aerosol Extinction?

    NASA Technical Reports Server (NTRS)

    Schmid, Beat; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.

    2005-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (MOP, May 2003) yielded one of the best measurement sets obtained to-date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(sub ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well characterized aerosol sampling ability carrying well proven and new aerosol instrumentation, devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from 6 different instuments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, ground-based Raman lidar and 2 ground-based elastic backscatter lidars. We find the in-situ measured sigma(sub ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002 - 0.004 K/m equivalent to 12-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(sub ep)(lambda) are higher. An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP and we expect better agreement from the recently restored system looking at the collective results from 6 field campaigns conducted since 1996, airborne in situ measurements of sigma(sub ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(sub ep)(lambda). On the other hand, sigma(sub ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated with measuring the tropospheric vertical profile of the ambient aerosol extinction with current state of-the art instrumentation is 15-20% at visible wavelengths and potentially larger in

  7. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Kittaka, C.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R. R.; Cook, A. L.; Haper, D. B.

    2008-01-01

    Aerosol extinction profiles are derived from backscatter data by constraining the retrieval with column aerosol optical thickness (AOT), for example from coincident MODIS observations and without reliance on a priori assumptions about aerosol type or optical properties. The backscatter data were acquired with the NASA Langley High Spectral Resolution Lidar (HSRL). The HSRL also simultaneously measures extinction independently, thereby providing an ideal data set for evaluating the constrained retrieval of extinction from backscatter. We will show constrained extinction retrievals using various sources of column AOT, and examine comparisons with the HSRL extinction measurements and with a similar retrieval using data from the CALIOP lidar on the CALIPSO satellite.

  8. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with a version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of Aerosol Optical Depth (AOD) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in the northern India. The WRF-Chem model is found to underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model low-bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AODmore » and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day −1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  9. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE PAGES

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; ...

    2015-06-19

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with a version of the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of Aerosol Optical Depth (AOD) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in the northern India. The WRF-Chem model is found to underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model low-bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AODmore » and extinction profiles averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day −1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  10. Comparisons of Airborne HSRL and Modeled Aerosol Profiles

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Ismail, S.; Rogers, R. R.; Notari, A.; Berkoff, T.; Butler, C. F.; Collins, J. E., Jr.; Fenn, M. A.; Scarino, A. J.; Clayton, M.; Mueller, D.; Chemyakin, E.; Fast, J. D.; Berg, L. K.; Randles, C. A.; Colarco, P. R.; daSilva, A.

    2014-12-01

    Aerosol profiles derived from a regional and a global model are compared with aerosol profiles acquired by NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidars (HSRLs) during recent field missions. We compare simulated aerosol profiles obtained from the WRF-Chem regional model with those measured by the airborne HSRL-2 instrument over the Atlantic Ocean east of Cape Cod in July 2012 during the Department of Energy Two-Column Aerosol Project (TCAP). While deployed on the LaRC King Air during TCAP, HSRL-2 acquired profiles of aerosol extinction at 355 and 532 nm, as well as aerosol backscatter and depolarization at 355, 532, and 1064 nm. Additional HSRL-2 data products include profiles of aerosol type, mixed layer depth, and aerosol microphysical parameters (e.g. effective radius, concentration). The HSRL-2 and WRF-Chem aerosol profiles are compared along the aircraft flight tracks. HSRL-2 profiles acquired during the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission over Houston during September 2013 are compared with the NASA Goddard Earth Observing System global model, version 5 (GEOS-5) profiles. In addition to comparing backscatter and extinction profiles, the fraction of aerosol extinction and optical thickness from various aerosol species from GEOS-5 are compared with aerosol extinction and optical thickness contributed by aerosol types derived from HSRL-2 data. We also compare aerosol profiles modeled by GEOS-5 with those measured by the airborne LaRC DIAL/HSRL instrument during August and September 2013 when it was deployed on the NASA DC-8 for the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) mission. DIAL/HSRL measured extinction (532 nm), backscatter (532 and 1064 nm), and depolarization profiles (532 and 1064 nm) in both nadir and zenith directions during long transects over the

  11. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profilesmore » averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48% more heating in the atmosphere and 21% more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7K day −1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  12. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE PAGES

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.; ...

    2016-01-18

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profilesmore » averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48% more heating in the atmosphere and 21% more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7K day −1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  13. Analysis of DIAL/HSRL aerosol backscatter and extinction profiles during the SEAC4RS campaign with an aerosol assimilation system

    NASA Astrophysics Data System (ADS)

    Weaver, C. J.; da Silva, A. M., Jr.; Colarco, P. R.; Randles, C. A.

    2015-12-01

    We retrieve aerosol concentrations and optical information from vertical profiles of airborne 532 nm extinction and 532 and 1064 nm backscatter measurements made during the SEAC4RS summer 2013 campaign. The observations are from the High Spectral Resolution Lidar (HSRL) Airborne Differential Absorption Lidar (DIAL) on board the NASA DC-8. Instead of retrieving information about aerosol microphysical properties such as indexes of refraction, we seek information more directly applicable to an aerosol transport model - in our case the Goddard Chemistry Aerosol Radiation and Transport (GOCART) module used in the GEOS-5 Earth modeling system. A joint atmosphere/aerosol mini-reanalysis was performed for the SEAC4RS period using GEOS-5. The meteorological reanalysis followed the MERRA-2 atmospheric reanalysis protocol, and aerosol information from MODIS, MISR, and AERONET provided a constraint on the simulated aerosol optical depth (i.e., total column loading of aerosols). We focus on the simulated concentrations of 10 relevant aerosol species simulated by the GOCART module: dust, sulfate, and organic and black carbon. Our first retrieval algorithm starts with the SEAC4RS mini-reanalysis and adjusts the concentration of each GOCART aerosol species so that differences between the observed and simulated backscatter and extinction measurements are minimized. In this case, too often we are unable to simulate the observations by simple adjustment of the aerosol concentrations. A second retrieval approach adjusts both the aerosol concentrations and the optical parameters (i.e., assigned mass extinction efficiency) associated with each GOCART species. We present results from DC-8 flights over smoke from forest fires over the western US using both retrieval approaches. Finally, we compare our retrieved quantities with in-situ observations of aerosol absorption, scattering, and mass concentrations at flight altitude.

  14. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 1; Methods and Comparisons

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Leifer, R.

    1998-01-01

    This paper examines the aerosol backscattering and extinction profiles measured at night by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site in April 1994. These lidar data are used to derive aerosol profiles for altitudes between 0.0 1 5 and 5 km. Since this lidar detects Raman scattering from nitrogen and oxygen molecules as well as the elastic scattering from molecules and aerosols, it measures both aerosol backscattering and extinction simultaneously. The aerosol extinction/backscattering ratio varied between approximately 30 sr and 75 sr at 351 nm. Aerosol optical thicknesses derived by integrating the lidar profiles of aerosol extinction measured at night between 0. I and 5 km are found to be about 10-40% lower than those measured by a Sun photometer during the day. This difference is attributed to the contribution by stratospheric aerosols not included in the lidar estimates as well as to diurnal differences in aerosol properties and concentrations. Aerosol profiles close to the surface were acquired by pointing the lidar nearly horizontally. Measurements of aerosol scattering from a tower-mounted nephelometer are found to be 40% lower than lidar measurements of aerosol extinction over a wide range of relative humidities even after accounting for the difference in wavelengths. The reasons for this difference are not clear but may be due to the inability of the nephelometer to accurately measure scattering by large particles.

  15. Radiative and thermodynamic responses to aerosol extinction profiles during the pre-monsoon month over South Asia

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feng, Y.; Kotamarthi, V. R.; Coulter, R.

    Aerosol radiative effects and thermodynamic responses over South Asia are examined with the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for March 2012. Model results of aerosol optical depths (AODs) and extinction profiles are analyzed and compared to satellite retrievals and two ground-based lidars located in northern India. The WRF-Chem model is found to heavily underestimate the AOD during the simulated pre-monsoon month and about 83 % of the model's low bias is due to aerosol extinctions below ~2 km. Doubling the calculated aerosol extinctions below 850 hPa generates much better agreement with the observed AOD and extinction profilesmore » averaged over South Asia. To separate the effect of absorption and scattering properties, two runs were conducted: in one run (Case I), the calculated scattering and absorption coefficients were increased proportionally, while in the second run (Case II) only the calculated aerosol scattering coefficient was increased. With the same AOD and extinction profiles, the two runs produce significantly different radiative effects over land and oceans. On the regional mean basis, Case I generates 48 % more heating in the atmosphere and 21 % more dimming at the surface than Case II. Case I also produces stronger cooling responses over the land from the longwave radiation adjustment and boundary layer mixing. These rapid adjustments offset the stronger radiative heating in Case I and lead to an overall lower-troposphere cooling up to -0.7 K day −1, which is smaller than that in Case II. Over the ocean, direct radiative effects dominate the heating rate changes in the lower atmosphere lacking such surface and lower atmosphere adjustments due to fixed sea surface temperature, and the strongest atmospheric warming is obtained in Case I. Consequently, atmospheric dynamics (boundary layer heights and meridional circulation) and thermodynamic processes (water vapor and cloudiness) are shown to respond

  16. Investigation of shortcomings in simulated aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Park, S.; Allen, R.

    2017-12-01

    The vertical distribution of aerosols is one important factor for aerosol radiative forcing. Previous studies show that climate models poorly reproduce the aerosol vertical profile, with too much aerosol aloft in the upper troposphere. This bias may be related to several factors, including excessive convective mass flux and wet removal. In this study, we evaluate the aerosol vertical profile from several Coupled Model Intercomparison Project 5 (CMIP5) models, as well as the Community Atmosphere Model 5 (CAM5), relative to the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO). The results show that all models significantly underestimate extinction coefficient in the lower troposphere, while overestimating extinction coefficient in the upper troposphere. In addition, the majority of models indicate a land-ocean dependence in the relationship between aerosol extinction coefficient in the upper troposphere and convective mass flux. Over the continents, more convective mass flux is related to more aerosol aloft; over the ocean, more convective mass flux is associated with less aerosol in upper troposphere. Sensitivity experiments are conducted to investigate the role that convection and wet deposition have in contributing to the deficient simulation of the vertical aerosol profile, including the land-ocean dependence.

  17. How Well do State-of-the-Art Techniques Measuring the Vertical Profile of Tropospheric Aerosol Extinction Compare?

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Ferrare, R.; Flynn, C.; Elleman, R.; Covert, D.; Strawa, A.; Welton, E.; Turner, D.; Jonsson, H.; Redemann, J.; hide

    2006-01-01

    The recent Department of Energy Atmospheric Radiation Measurement (ARM) Aerosol Intensive Operations Period (AIOP, May 2003) yielded one of the best measurement sets obtained to date to assess our ability to measure the vertical profile of ambient aerosol extinction sigma(ep)(lambda) in the lower troposphere. During one month, a heavily instrumented aircraft with well-characterized aerosol sampling ability carrying well-proven and new aerosol instrumentation devoted most of the 60 available flight hours to flying vertical profiles over the heavily instrumented ARM Southern Great Plains (SGP) Climate Research Facility (CRF). This allowed us to compare vertical extinction profiles obtained from six different instruments: airborne Sun photometer (AATS-14), airborne nephelometer/absorption photometer, airborne cavity ring-down system, groundbased Raman lidar, and two ground-based elastic backscatter lidars. We find the in situ measured sigma(ep)(lambda) to be lower than the AATS-14 derived values. Bias differences are 0.002-0.004 Km!1 equivalent to 13-17% in the visible, or 45% in the near-infrared. On the other hand, we find that with respect to AATS-14, the lidar sigma(ep)(lambda) are higher: Bias differences are 0.004 Km(-1) (13%) and 0.007 Km(-1) (24%) for the two elastic backscatter lidars (MPLNET and MPLARM, lambda = 523 nm) and 0.029 Km(-1) (54%) for the Raman lidar (lambda = 355 nm). An unnoticed loss of sensitivity of the Raman lidar had occurred leading up to AIOP, and we expect better agreement from the recently restored system. Looking at the collective results from six field campaigns conducted since 1996, airborne in situ measurements of sigma(ep)(lambda) tend to be biased slightly low (17% at visible wavelengths) when compared to airborne Sun photometer sigma(ep)(lambda). On the other hand, sigma(ep)(lambda) values derived from lidars tend to have no or positive biases. From the bias differences we conclude that the typical systematic error associated

  18. Raman Lidar Profiling of Aerosols Over the Central US; Diurnal Variability and Comparisons with the GOCART Model

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Chin, M.; Clayton, M.; Turner, D.

    2002-01-01

    We use profiles of aerosol extinction, water vapor mixing ratio, and relative humidity measured by the ARM SGP Raman lidar in northern Oklahoma to show how the vertical distributions of aerosol extinction and water vapor vary throughout the diurnal cycle. While significant (20-30%) variations in aerosol extinction occurred near the surface as well as aloft, smaller (approximately 10%) variations were observed in the diurnal variability of aerosol optical thickness (AOT). The diurnal variations in aerosol extinction profiles are well correlated with corresponding variations in the average relative humidity profiles. The water vapor mixing ratio profiles and integrated water vapor amounts generally show less diurnal variability. The Raman lidar profiles are also used to evaluate the aerosol optical thickness and aerosol extinction profiles simulated by the GOCART global aerosol model. Initial comparisons show that the AOT simulated by GOCART was in closer agreement with the AOT derived from the Raman lidar and Sun photometer measurements during November 2000 than during September 2000. For both months, the vertical variability in average aerosol extinction profiles simulated by GOCART is less than the variability in the corresponding Raman lidar profiles.

  19. MAX-DOAS retrieval of aerosol extinction properties in Madrid, Spain

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Cuevas, Carlos A.; Frieß, Udo; Saiz-Lopez, Alfonso

    2017-04-01

    We present Multi-axis differential optical absorption spectroscopy (MAX-DOAS) measurements performed in the urban environment of Madrid, Spain, from March to September 2015. The O4 absorption in the ultraviolet (UV) spectral region was used to retrieve the aerosol extinction profile using an inversion algorithm. The results show a good agreement between the hourly retrieved aerosol optical depth (AOD) and the correlative Aerosol Robotic Network (AERONET) product. Higher AODs are found in the summer season due to the more frequent occurrence of Saharan dust intrusions. The surface aerosol extinction coefficient as retrieved by the MAX-DOAS measurements was also compared to in situ PM2:5 concentrations. The level of agreement between both measurements indicates that the MAX-DOAS retrieval has the ability to characterize the extinction of aerosol particles near the surface. The retrieval algorithm was also used to study a case of severe dust intrusion on 12 May 2015. The capability of the MAX-DOAS retrieval to recognize the dust event including an elevated particle layer is investigated along with air mass back-trajectory analysis.

  20. Vertical distribution of aerosol extinction cross section and inference of aerosol imaginary index in the troposphere by lidar technique

    NASA Technical Reports Server (NTRS)

    Spinhirne, J. D.; Reagan, J. A.; Herman, B. M.

    1980-01-01

    The paper reports on vertical profiles of aerosol extinction and backscatter in the troposphere which were obtained from multi zenith angle lidar measurements. It is reported that a direct slant path solution was found to be not possible due to horizontal inhomogeneity of the atmosphere. Attention is given to the use of a regression analysis with respect to zenith angle for a layer integration of the angle dependent lidar equation in order to determine the optical thickness and aerosol extinction-to-backscatter ratio for defined atmospheric layers and the subsequent evaluation of cross-section profiles.

  1. In Situ Measurement of Aerosol Extinction

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Castaneda, R.; Owano, T. G.; Bear, D.; Gore, Warren J. (Technical Monitor)

    2001-01-01

    Aerosols are important contributors to the radiative forcing in the atmosphere. Much of the uncertainty in our knowledge of climate forcing is due to uncertainties in the radiative forcing due to aerosols as illustrated in the IPCC reports of the last ten years. Improved measurement of aerosol optical properties, therefore, is critical to an improved understanding of atmospheric radiative forcing. Additionally, attempts to reconcile in situ and remote measurements of aerosol radiative properties have generally not been successful. This is due in part to the fact that it has been impossible to measure aerosol extinction in situ in the past. In this presentation we introduce a new instrument that employs the techniques used in cavity ringdown spectroscopy to measure the aerosol extinction and scattering coefficients in situ. A prototype instrument has been designed and tested in the lab and the field. It is capable of measuring aerosol extinction coefficient to 2x10(exp -6) per meter. This prototype instrument is described and results are presented.

  2. Study of MPLNET-Derived Aerosol Climatology over Kanpur, India, and Validation of CALIPSO Level 2 Version 3 Backscatter and Extinction Products

    NASA Technical Reports Server (NTRS)

    Misra, Amit; Tripathi, S. N.; Kaul, D. S.; Welton, Ellsworth J.

    2012-01-01

    The level 2 aerosol backscatter and extinction profiles from the NASA Micropulse Lidar Network (MPLNET) at Kanpur, India, have been studied from May 2009 to September 2010. Monthly averaged extinction profiles from MPLNET shows high extinction values near the surface during October March. Higher extinction values at altitudes of 24 km are observed from April to June, a period marked by frequent dust episodes. Version 3 level 2 Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) aerosol profile products have been compared with corresponding data from MPLNET over Kanpur for the above-mentioned period. Out of the available backscatter profiles, the16 profiles used in this study have time differences less than 3 h and distances less than 130 km. Among these profiles, four cases show good comparison above 400 m with R2 greater than 0.7. Comparison with AERONET data shows that the aerosol type is properly identified by the CALIOP algorithm. Cloud contamination is a possible source of error in the remaining cases of poor comparison. Another source of error is the improper backscatter-to-extinction ratio, which further affects the accuracy of extinction coefficient retrieval.

  3. The impacts of aerosol loading, composition, and water uptake on aerosol extinction variability in the Baltimore-Washington, D.C. region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2016-01-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type - such as composition, size, and hygroscopicity - and to the surrounding atmosphere, such as temperature, relative humidity (RH), and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in situ atmospheric profiling in the Baltimore, MD-Washington, D.C. region was performed during 14 flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties, and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed, with high-loading days having a proportionally larger percentage of sulfate due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of inorganics increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity, causing an increase in the water content of the aerosol. Conversely, low-aerosol-loading days had lower sulfate and higher black carbon contributions, causing lower single-scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km, decreasing to 35 ng m-3 in the free troposphere (above

  4. Measurements of Aerosol Vertical Profiles and Optical Properties during INDOEX 1999 Using Micro-Pulse Lidars

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Quinn, Patricia K.; Flatau, Piotr J.; Markowicz, Krzysztof; Campbell, James R.; Spinhirne, James D.; Gordon, Howard R.; Johnson, James E.; Starr, David OC. (Technical Monitor)

    2001-01-01

    Micro-pulse lidar systems (MPL) were used to measure aerosol properties during the Indian Ocean Experiment (INDOEX) 1999 field phase. Measurements were made from two platforms: the NOAA ship RN Ronald H. Brown, and the Kaashidhoo Climate Observatory (KCO) in the Maldives. Sunphotometers were used to provide aerosol optical depths (AOD) needed to calibrate the MPL. This study focuses on the height distribution and optical properties (at 523 nm) of aerosols observed during the campaign. The height of the highest aerosols (top height) was calculated and found to be below 4 km for most of the cruise. The marine boundary layer (MBL) top was calculated and found to be less than 1 km. MPL results were combined with air mass trajectories, radiosonde profiles of temperature and humidity, and aerosol concentration and optical measurements. Humidity varied from approximately 80% near the surface to 50% near the top height during the entire cruise. The average value and standard deviation of aerosol optical parameters were determined for characteristic air mass regimes. Marine aerosols in the absence of any continental influence were found to have an AOD of 0.05 +/- 0.03, an extinction-to-backscatter ratio (S-ratio) of 33 +/- 6 sr, and peak extinction values around 0.05/km (near the MBL top). The marine results are shown to be in agreement with previously measured and expected values. Polluted marine areas over the Indian Ocean, influenced by continental aerosols, had AOD values in excess of 0.2, S-ratios well above 40 sr, and peak extinction values approximately 0.20/km (near the MBL top). The polluted marine results are shown to be similar to previously published values for continental aerosols. Comparisons between MPL derived extinction near the ship (75 m) and extinction calculated at ship-level using scattering measured by a nephelometer and absorption using a PSAP were conducted. The comparisons indicated that the MPL algorithm (using a constant S-ratio throughout the

  5. Vertical Profiles of Aerosol Optical Properties Over Central Illinois and Comparison with Surface and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Sheridan P. J.; Andrews, E.; Ogren, J A.; Tackett, J. L.; Winker, D. M.

    2012-01-01

    Between June 2006 and September 2009, an instrumented light aircraft measured over 400 vertical profiles of aerosol and trace gas properties over eastern and central Illinois. The primary objectives of this program were to (1) measure the in situ aerosol properties and determine their vertical and temporal variability and (2) relate these aircraft measurements to concurrent surface and satellite measurements. Underflights of the CALIPSO satellite show reasonable agreement in a majority of retrieved profiles between aircraft-measured extinction at 532 nm (adjusted to ambient relative humidity) and CALIPSO-retrieved extinction, and suggest that routine aircraft profiling programs can be used to better understand and validate satellite retrieval algorithms. CALIPSO tended to overestimate the aerosol extinction at this location in some boundary layer flight segments when scattered or broken clouds were present, which could be related to problems with CALIPSO cloud screening methods. The in situ aircraft-collected aerosol data suggest extinction thresholds for the likelihood of aerosol layers being detected by the CALIOP lidar. These statistical data offer guidance as to the likelihood of CALIPSO's ability to retrieve aerosol extinction at various locations around the globe.

  6. Characterizing the Vertical Profile of Aerosol Particle Extinction and Linear Depolarization over Southeast Asia and the Maritime Continent: The 2007-2009 View from CALIOP

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Tackett, Jason L.; Chew, Boon Ning; Welton, Ellsworth J.; Shimizu, Atsushi; Sugimoto, Nobuo; Aoki, Kazuma; hide

    2012-01-01

    Vertical profiles of 0.532 µm aerosol particle extinction coefficient and linear volume depolarization ratio are described for Southeast Asia and the Maritime Continent. Quality-screened and cloud-cleared Version 3.01 Level 2 NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) 5-km Aerosol Profile datasets are analyzed from 2007 to 2009. Numerical simulations from the U.S. Naval Aerosol Analysis and Predictive System (NAAPS), featuring two-dimensional variational assimilation of NASA Moderate Resolution Imaging Spectroradiometer and Multi-angle Imaging Spectro- Radiometer quality-assured datasets, combined with regional ground-based lidar measurements, are considered for assessing CALIOP retrieval performance, identifying bias, and evaluating regional representativeness. CALIOP retrievals of aerosol particle extinction coefficient and aerosol optical depth (AOD) are high over land and low over open waters relative to NAAPS (0.412/0.312 over land for all data points inclusive, 0.310/0.235 when the per bin average is used and each is treated as single data points; 0.102/0.151 and 0.086/0.124, respectively, over ocean). Regional means, however, are very similar (0.180/0.193 for all data points and 0.155/0.159 when averaged per normalized bin), as the two factors offset one another. The land/ocean offset is investigated, and discrepancies attributed to interpretation of particle composition and a-priori assignment of the extinction-to-backscatter ratio ("lidar ratio") necessary for retrieving the extinction coefficient from CALIOP signals. Over land, NAAPS indicates more dust present than CALIOP algorithms are identifying, indicating a likely assignment of a higher lidar ratio representative of more absorptive particles. NAAPS resolvesmore smoke overwater than identified with CALIOP, indicating likely usage of a lidar ratio characteristic of less absorptive particles to be applied that biases low AOD there. Over open waters except within the Bay of Bengal

  7. The Influence of Aerosol Hygroscopicity on Retrieving the Aerosol Extincting Coefficient from MPL Data

    NASA Astrophysics Data System (ADS)

    Zhao, G.; Zhao, C.

    2016-12-01

    Micro-pulse Lidar (MPL) measurements have been widely used to profile the ambient aerosol extincting coefficient(). Lidar Ratio (LR) ,which highly depends on the particle number size distribution (PNSD) and aerosol hygroscopicity, is the most important factor to retrieve the profile. A constant AOD constrained LR is usually used in current algorithms, which would lead to large bias when the relative humidity (RH) in the mixed layer is high. In this research, the influences of PNSD, aerosol hygroscopicity and RH profiles on the vertical variation of LR were investigated based on the datasets from field measurements in the North China Plain (NCP). Results show that LR can have an enhancement factor of more than 120% when the RH reaches to 92%. A new algorithm of retrieving the profile is proposed based on the variation of LR due to aerosol hygroscopicity. The magnitude and vertical structures of retrieved using this method can be significantly different to that of the fiexed LR method. The relative difference can reach up to 40% when the RH in the mixed layer is higher than 90% . Sensitivity studies show that RH profile and PNSD affect most on the retrieved by fiexed LR method. In view of this, a scheme of LR enhancement factor by RH is proposed in the NCP. The relative differnce of the calculated between using this scheme and the new algorithm with the variable LR can be less than 10%.

  8. OMPS Limb Profiler: Extending SAGE and CALIPSO Stratospheric Aerosol Records

    NASA Astrophysics Data System (ADS)

    Taha, G.; Bhartia, P. K.; Chen, Z.; Xu, P.; Loughman, R. P.; Jaross, G.

    2017-12-01

    The OMPS LP instrument is designed to provide high vertical resolution ozone and aerosol profiles from measurements of the scattered solar radiation in the 290-1000 nm spectral range. It collected its first Earth limb measurement in January 10, 2012, and continues to provide daily global measurements of ozone and aerosol profiles from the cloud top up to 60 km and 40 km respectively. The relatively high vertical and spatial sampling allow detection and tracking periodic events when aerosol particles are injected into the stratosphere, such as volcanic eruptions or meteor explosions. OMPS LP can extend the long-term records of stratospheric aerosol at high vertical resolution produced by variety of sensors, such as SAGEII, GOMOS, OSIRIS and CALIPSO. Most of these instruments ceased to operate or well beyond their designed lifetime. After an absence of over a decade, SAGE III/ISS was launched earlier this year and expected to resume the high quality aerosol data record. OMPS LP is also schedule to fly on JPSS-2 and 3. In this study we will examine the suitability of using LP profiles to continue the stratospheric aerosol records beyond SAGE, OSIRIS, and CALIPSO. We will compare OMPS LP released V1.0 aerosol extinction measurements to OSIRIS and CALIPSO. Initial results shows good agreement with OSIRIS measurements to within 20%, with larger bias in the southern hemisphere. To test the effect of the assumed aerosol size model (ASD) and phase function, we compare measurements taken at similar location and time with different viewing geometry. Comparison of ascending and descending aerosol extinction daily zonal means at high latitudes shows systematic bias that is well correlated with the solar scattering angle, indicating ASD uncertainties up to 30%. In addition, results showing latitudinal, and temporal variability of stratospheric aerosol extinction and optical depth for the three instruments will also be presented and compared. We will also present OMPS LP aerosol

  9. Broadband Measurement of Aerosol Extinction in the Visible Range

    NASA Astrophysics Data System (ADS)

    He, Quanfu; Bluvshtein, Nir; Segev, Lior; Flores, Michel; Rudich, Yinon; Washenfelder, Rebecca; Brown, Steven

    2017-04-01

    Atmospheric aerosols influence the Earth's radiative budget directly by scattering and absorbing incoming solar radiation. Aerosol direct forcing remains one of the largest uncertainties in quantifying the role that aerosols play in the Earth's radiative budget. The optical properties of aerosols vary as a function of wavelength, but few measurements reported the wavelength dependence of aerosol extinction cross section and complex refractive indices, particularly in the blue and visible spectral range. There is also currently a large gap in our knowledge of how the optical properties evolve as a function of atmospheric aging in the visible spectrum. In this study, we constructed a new and novel laboratory instrument to measure aerosol extinction as a function of wavelength, using cavity enhanced spectroscopy with a white light source. This broadband cavity enhanced spectroscopy (BBCES) covers the 395-700 nm spectral region using a broadband light source and a grating spectrometer with charge-coupled device detector (CCD). We evaluated this BBCES by measuring extinction cross section for aerosols that are pure scattering, slightly absorbing and strongly absorbing atomized from standard materials. We also retrieved the refractive indices from the measured extinction cross sections. Secondary organic aerosols from biogenic and anthropogenic precursors were "aged" to differential time scales (1 to 10 days) in an Oxidation Flow Reactor (OFR) under the combined influence of OH, O3 and UV light. The new BBCES was used to online measure the extinction cross sections of the SOA. This talk will provide a comprehensive understanding of aerosol optical properties alerting during aging process in the 395 - 700 nm spectrum.

  10. Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles From Surface Measurements

    NASA Technical Reports Server (NTRS)

    Ghan, Stephen J.; Rissman, Tracey A.; Ellman, Robert; Ferrare, Richard A.; Turner, David; Flynn, Connor; Wang, Jian; Ogren, John; Hudson, James; Jonsson, Haflidi H.; hide

    2006-01-01

    If the aerosol composition and size distribution below cloud are uniform, the vertical profile of cloud condensation nuclei (CCN) concentration can be retrieved entirely from surface measurements of CCN concentration and particle humidification function and surface-based retrievals of relative humidity and aerosol extinction or backscatter. This provides the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The retrieval works better for supersaturations of 0.1% than for 1% because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. If in situ measurements of extinction are used, the retrieval explains a majority of the CCN variance at high supersaturation for at least two and perhaps five of the eight flights examined. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.

  11. Optical extinction of highly porous aerosol following atmospheric freeze drying

    NASA Astrophysics Data System (ADS)

    Adler, Gabriela; Haspel, Carynelisa; Moise, Tamar; Rudich, Yinon

    2014-06-01

    Porous glassy particles are a potentially significant but unexplored component of atmospheric aerosol that can form by aerosol processing through the ice phase of high convective clouds. The optical properties of porous glassy aerosols formed from a freeze-dry cycle simulating freezing and sublimation of ice particles were measured using a cavity ring down aerosol spectrometer (CRD-AS) at 532 nm and 355 nm wavelength. The measured extinction efficiency was significantly reduced for porous organic and mixed organic-ammonium sulfate particles as compared to the extinction efficiency of the homogeneous aerosol of the same composition prior to the freeze-drying process. A number of theoretical approaches for modeling the optical extinction of porous aerosols were explored. These include effective medium approximations, extended effective medium approximations, multilayer concentric sphere models, Rayleigh-Debye-Gans theory, and the discrete dipole approximation. Though such approaches are commonly used to describe porous particles in astrophysical and atmospheric contexts, in the current study, these approaches predicted an even lower extinction than the measured one. Rather, the best representation of the measured extinction was obtained with an effective refractive index retrieved from a fit to Mie scattering theory assuming spherical particles with a fixed void content. The single-scattering albedo of the porous glassy aerosols was derived using this effective refractive index and was found to be lower than that of the corresponding homogeneous aerosol, indicating stronger relative absorption at the wavelengths measured. The reduced extinction and increased absorption may be of significance in assessing direct, indirect, and semidirect forcing in regions where porous aerosols are expected to be prevalent.

  12. Validation of aerosol extinction and water vapor profiles from routine Atmospheric Radiation Measurement Program Climate Research Facility measurements

    NASA Astrophysics Data System (ADS)

    Schmid, Beat; Flynn, Connor J.; Newsom, Rob K.; Turner, David D.; Ferrare, Richard A.; Clayton, Marian F.; Andrews, Elisabeth; Ogren, John A.; Johnson, Roy R.; Russell, Philip B.; Gore, Warren J.; Dominguez, Roseanne

    2009-11-01

    The accuracy with which vertical profiles of aerosol extinction σep(λ) can be measured using routine Atmospheric Radiation Measurement Program (ARM) Climate Research Facility (ACRF) measurements and was assessed using data from two airborne field campaigns, the ARM Aerosol Intensive Operation Period (AIOP, May 2003), and the Aerosol Lidar Validation Experiment (ALIVE, September 2005). This assessment pertains to the aerosol at its ambient concentration and thermodynamic state (i.e., σep(λ) either free of or corrected for sampling artifacts) and includes the following ACRF routine methods: Raman lidar, micropulse lidar (MPL), and in situ aerosol profiles (IAP) with a small aircraft. Profiles of aerosol optical depth τp(λ), from which the profiles of σep(λ) are derived through vertical differentiation, were measured by the NASA Ames Airborne Tracking 14-channel Sun photometer (AATS-14); these data were used as benchmark in this evaluation. The ACRF IAP σep(550 nm) were lower by 11% (during AIOP) and higher by 1% (during ALIVE) when compared to AATS-14. The ACRF MPL σep(523 nm) measurements were higher by 24% (AIOP) and 19-21% (ALIVE) compared to AATS-14, but the correlation improved significantly during ALIVE. In the AIOP, a second MPL operated by NASA showed a smaller positive bias (13%) with respect to AATS-14. The ACRF Raman lidar σep(355 nm) measurements were larger by 54% (AIOP) and by 6% (ALIVE) compared to AATS-14. The large bias in the Raman lidar measurements during AIOP stemmed from a gradual loss of Raman lidar sensitivity starting about the end of 2001 going unnoticed until after AIOP. A major refurbishment and upgrade of the instrument and improvements to a data processing algorithm led to the significant improvement and very small bias in ALIVE. Finally, we find that during ALIVE the Raman lidar water vapor densities ρw are 8% larger when compared to AATS-14, whereas in situ measured ρw aboard two different aircraft are smaller than the

  13. Results of a comprehensive atmospheric aerosol-radiation experiment in the southwestern United States. I - Size distribution, extinction optical depth and vertical profiles of aerosols suspended in the atmosphere. II - Radiation flux measurements and

    NASA Technical Reports Server (NTRS)

    Deluisi, J. J.; Furukawa, F. M.; Gillette, D. A.; Schuster, B. G.; Charlson, R. J.; Porch, W. M.; Fegley, R. W.; Herman, B. M.; Rabinoff, R. A.; Twitty, J. T.

    1976-01-01

    Results are reported for a field test that was aimed at acquiring a sufficient set of measurements of aerosol properties required as input for radiative-transfer calculations relevant to the earth's radiation balance. These measurements include aerosol extinction and size distributions, vertical profiles of aerosols, and radiation fluxes. Physically consistent, vertically inhomogeneous models of the aerosol characteristics of a turbid atmosphere over a desert and an agricultural region are constructed by using direct and indirect sampling techniques. These results are applied for a theoretical interpretation of airborne radiation-flux measurements. The absorption term of the complex refractive index of aerosols is estimated, a regional variation in the refractive index is noted, and the magnitude of solar-radiation absorption by aerosols and atmospheric molecules is determined.

  14. Two-Column Aerosol Project: Aerosol Light Extinction Measurements Field Campaign Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dubey, Manvendra; Aiken, Allison; Berg, Larry

    We deployed Aerodyne Research Inc.’s first Cavity Attenuated Phase Shift extinction (CAPS PMex) monitor (built by Aerodyne) that measures light extinction by using a visible-light-emitting diode (LED) as a light source, a sample cell incorporating two high-reflectivity mirrors centered at the wavelength of the LED, and a vacuum photodiode detector in Cape Cod in 2012/13 for the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Two-Column Aerosol Project (TCAP). The efficacy of this instrument is based on the fact that aerosols are broadband scatterers and absorbers of light. The input LED is square-wave modulated and passedmore » through the sample cell that distorts it due to exponential decay by aerosol light absorption and scattering; this is measured at the detector. The amount of phase shift of the light at the detector is used to determine the light extinction. This extinction measurement provides an absolute value, requiring no calibration. The goal was to compare the CAPS performance with direct measurements of absorption with ARM’s baseline photoacoustic soot spectrometer (PASS-3) and nephelometer instruments to evaluate its performance.« less

  15. An Accuracy Assessment of the CALIOP/CALIPSO Version 2/Version 3 Daytime Aerosol Extinction Product Based on a Detailed Multi-Sensor, Multi-Platform Case Study

    NASA Technical Reports Server (NTRS)

    Kacenelenbogen, M.; Vaughan, M. A.; Redemann, J.; Hoff, R. M.; Rogers, R. R.; Ferrare, R. A.; Russell, P. B.; Hostetler, C. A.; Hair, J. W.; Holben, B. N.

    2011-01-01

    The Cloud Aerosol LIdar with Orthogonal Polarization (CALIOP), on board the CALIPSO platform, has measured profiles of total attenuated backscatter coefficient (level 1 products) since June 2006. CALIOP s level 2 products, such as the aerosol backscatter and extinction coefficient profiles, are retrieved using a complex succession of automated algorithms. The goal of this study is to help identify potential shortcomings in the CALIOP version 2 level 2 aerosol extinction product and to illustrate some of the motivation for the changes that have been introduced in the next version of CALIOP data (version 3, released in June 2010). To help illustrate the potential factors contributing to the uncertainty of the CALIOP aerosol extinction retrieval, we focus on a one-day, multi-instrument, multiplatform comparison study during the CALIPSO and Twilight Zone (CATZ) validation campaign on 4 August 2007. On that day, we observe a consistency in the Aerosol Optical Depth (AOD) values recorded by four different instruments (i.e. spaceborne MODerate Imaging Spectroradiometer, MODIS: 0.67 and POLarization and Directionality of Earth s Reflectances, POLDER: 0.58, airborne High Spectral Resolution Lidar, HSRL: 0.52 and ground-based AErosol RObotic NETwork, AERONET: 0.48 to 0.73) while CALIOP AOD is a factor of two lower (0.32 at 532 nm). This case study illustrates the following potential sources of uncertainty in the CALIOP AOD: (i) CALIOP s low signal-to-noise ratio (SNR) leading to the misclassification and/or lack of aerosol layer identification, especially close to the Earth s surface; (ii) the cloud contamination of CALIOP version 2 aerosol backscatter and extinction profiles; (iii) potentially erroneous assumptions of the aerosol extinction-to-backscatter ratio (Sa) used in CALIOP s extinction retrievals; and (iv) calibration coefficient biases in the CALIOP daytime attenuated backscatter coefficient profiles. The use of version 3 CALIOP extinction retrieval for our case

  16. Vertical Profiles of Aerosol Volume from High Spectral Resolution Infrared Transmission Measurements: Results

    NASA Technical Reports Server (NTRS)

    Eldering, Annmarie; Kahn, Brian H.; Mills, Franklin P.; Irion, Fredrick W.; Steele, Helen M.; Gunson, Michael R.

    2004-01-01

    The high-resolution infrared absorption spectra of the Atmospheric Trace Molecule Spectroscopy (ATMOS) experiment are utilized to derive vertical profiles of sulfate aerosol volume density and extinction coefficient. Following the eruption of Mt. Pinatubo in June 1991, the ATMOS spectra obtained on three Space Shuttle missions (1992, 1993, and 1994) provide a unique opportunity to study the global stratospheric sulfate aerosol layer shortly after a major volcanic eruption and periodically during the decay phase. Synthetic sulfate aerosol spectra are fit to the observed spectra, and a global fitting inversion routine is used to derive vertical profiles of sulfate aerosol volume density. Vertical profiles of sulfate aerosol volume density for the three missions over portions of the globe are presented, with the peak in aerosol volume density occurring from as low as 10 km (polar latitudes) to as high as 20 km (subtropical latitudes). Derived aerosol volume density is as high as 2-3.5 (mu)m(exp 3) per cubic centimeter +/-10% in 1992, decreasing to 0.2-0.5 (mu)m(exp 3) per cubic centimeter +/-20% in 1994, in agreement with other experiments. Vertical extinction profiles derived from ATMOS are compared with profiles from Improved Stratospheric And Mesospheric Sounder (ISAMS) and Cryogenic Limb Array Etalon Spectrometer (CLAES) that coincide in space and time and show good general agreement. The uncertainty of the ATMOS vertical profiles is similar to CLAES and consistently smaller than ISAMS at similar altitudes.

  17. Lidar Ratios for Dust Aerosols Derived From Retrievals of CALIPSO Visible Extinction Profiles Constrained by Optical Depths from MODIS-Aqua and CALIPSO/CloudSat Ocean Surface Reflectance Measurements

    NASA Technical Reports Server (NTRS)

    Young, Stuart A.; Josset, Damien B.; Vaughan, Mark A.

    2010-01-01

    CALIPSO's (Cloud Aerosol Lidar Infrared Pathfinder Satellite Observations) analysis algorithms generally require the use of tabulated values of the lidar ratio in order to retrieve aerosol extinction and optical depth from measured profiles of attenuated backscatter. However, for any given time or location, the lidar ratio for a given aerosol type can differ from the tabulated value. To gain some insight as to the extent of the variability, we here calculate the lidar ratio for dust aerosols using aerosol optical depth constraints from two sources. Daytime measurements are constrained using Level 2, Collection 5, 550-nm aerosol optical depth measurements made over the ocean by the MODIS (Moderate Resolution Imaging Spectroradiometer) on board the Aqua satellite, which flies in formation with CALIPSO. We also retrieve lidar ratios from night-time profiles constrained by aerosol column optical depths obtained by analysis of CALIPSO and CloudSat backscatter signals from the ocean surface.

  18. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Flores, J. M.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2013-04-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with the literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (± 0.03) + 0.19 (± 0.08)i at 360 nm and 1.63 (± 0.03) + 0.21 (± 0.05)i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (± 0.02) + 0.07 (± 0.06)i at 360 nm and 1.66 (± 0.02) + 0.06 (± 0.04)i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross section, and complex refractive index as a function of wavelength.

  19. Broadband measurements of aerosol extinction in the ultraviolet spectral region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Flores, J. M.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2013-01-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross-sections and complex refractive indices. We describe a new laboratory instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We determined aerosol extinction cross-sections and directly observed Mie scattering resonances for aerosols that are purely scattering (polystyrene latex spheres and ammonium sulfate), slightly absorbing (Suwannee River fulvic acid), and strongly absorbing (nigrosin dye). We describe an approach for retrieving refractive indices as a function of wavelength from the measured extinction cross-sections over the 360-420 nm wavelength region. The retrieved refractive indices for PSL and ammonium sulfate agree within uncertainty with literature values for this spectral region. The refractive index determined for nigrosin is 1.78 (±0.03) + 0.19 (±0.08) i at 360 nm and 1.53 (±0.03) + 0.21 (±0.05) i at 420 nm. The refractive index determined for Suwannee River fulvic acid is 1.71 (±0.02) + 0.07 (±0.06) i at 360 nm and 1.66 (±0.02) + 0.06 (±0.04) i at 420 nm. These laboratory results support the potential for a field instrument capable of determining ambient aerosol optical extinction, average aerosol extinction cross-section, and complex refractive index as a function of wavelength.

  20. Derivation of atmospheric extinction profiles and wind speed over the ocean from a satellite-borne lidar.

    PubMed

    Weinman, J A

    1988-10-01

    A simulated analysis is presented that shows that returns from a single-frequency space-borne lidar can be combined with data from conventional visible satellite imagery to yield profiles of aerosol extinction coefficients and the wind speed at the ocean surface. The optical thickness of the aerosols in the atmosphere can be derived from visible imagery. That measurement of the total optical thickness can constrain the solution to the lidar equation to yield a robust estimate of the extinction profile. The specular reflection of the lidar beam from the ocean can be used to determine the wind speed at the sea surface once the transmission of the atmosphere is known. The impact on the retrieved aerosol profiles and surface wind speed produced by errors in the input parameters and noise in the lidar measurements is also considered.

  1. Improvement of Raman lidar algorithm for quantifying aerosol extinction

    NASA Technical Reports Server (NTRS)

    Russo, Felicita; Whiteman, David; Demoz, Belay; Hoff, Raymond

    2005-01-01

    Aerosols are particles of different composition and origin and influence the formation of clouds which are important in atmospheric radiative balance. At the present there is high uncertainty on the effect of aerosols on climate and this is mainly due to the fact that aerosol presence in the atmosphere can be highly variable in space and time. Monitoring of the aerosols in the atmosphere is necessary to better understanding many of these uncertainties. A lidar (an instrument that uses light to detect the extent of atmospheric aerosol loading) can be particularly useful to monitor aerosols in the atmosphere since it is capable to record the scattered intensity as a function of altitude from molecules and aerosols. One lidar method (the Raman lidar) makes use of the different wavelength changes that occur when light interacts with the varying chemistry and structure of atmospheric aerosols. One quantity that is indicative of aerosol presence is the aerosol extinction which quantifies the amount of attenuation (removal of photons), due to scattering, that light undergoes when propagating in the atmosphere. It can be directly measured with a Raman lidar using the wavelength dependence of the received signal. In order to calculate aerosol extinction from Raman scattering data it is necessary to evaluate the rate of change (derivative) of a Raman signal with respect to altitude. Since derivatives are defined for continuous functions, they cannot be performed directly on the experimental data which are not continuous. The most popular technique to find the functional behavior of experimental data is the least-square fit. This procedure allows finding a polynomial function which better approximate the experimental data. The typical approach in the lidar community is to make an a priori assumption about the functional behavior of the data in order to calculate the derivative. It has been shown in previous work that the use of the chi-square technique to determine the most

  2. Spectral Aerosol Extinction (SpEx): A New Instrument for In situ Ambient Aerosol Extinction Measurements Across the UV/Visible Wavelength Range

    NASA Technical Reports Server (NTRS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Corr, C. A.; Dibb, J. E.; Greenslade, M. E.; Martin, R. F.; Moore, R. H.; Scheuer, E.; Shook, M. A.; hide

    2015-01-01

    We introduce a new instrument for the measurement of in situ ambient aerosol extinction over the 300-700 nm wavelength range, the Spectral Aerosol Extinction (SpEx) instrument. This measurement capability is envisioned to complement existing in situ instrumentation, allowing for simultaneous measurement of the evolution of aerosol optical, chemical, and physical characteristics in the ambient environment. In this work, a detailed description of the instrument is provided along with characterization tests performed in the laboratory. Measured spectra of NO2 and polystyrene latex spheres agreed well with theoretical calculations. Good agreement was also found with simultaneous aerosol extinction measurements at 450, 530, and 630 nm using CAPS PMex instruments in a series of 22 tests including non-absorbing compounds, dusts, soot, and black and brown carbon analogs. SpEx can more accurately distinguish the presence of brown carbon from other absorbing aerosol due to its 300 nm lower wavelength limit compared to measurements limited to visible wavelengths. In addition, the spectra obtained by SpEx carry more information than can be conveyed by a simple power law fit that is typically defined by the use of Angstrom Exponents. Future improvements aim at lowering detection limits and ruggedizing the instrument for mobile operation.

  3. Spectrally-resolved measurements of aerosol extinction at ultraviolet and visible wavelengths

    NASA Astrophysics Data System (ADS)

    Flores, M.; Washenfelder, R. A.; Brock, C. A.; Brown, S. S.; Rudich, Y.

    2012-12-01

    Aerosols play an important role in the Earth's radiative budget. Aerosol extinction includes both the scattering and absorption of light, and these vary with wavelength, aerosol diameter, and aerosol composition. Historically, aerosol absorption has been measured using filter-based or extraction methods that are prone to artifacts. There have been few investigations of ambient aerosol optical properties at the blue end of the visible spectrum and into the ultraviolet. Brown carbon is particularly important in this spectral region, because it both absorbs and scatters light, and encompasses a large and variable group of organic compounds from biomass burning and secondary organic aerosol. We have developed a laboratory instrument that combines new, high-power LED light sources with high-finesse optical cavities to achieve sensitive measurements of aerosol optical extinction. This instrument contains two broadband channels, with spectral coverage from 360 - 390 nm and 385 - 420 nm. Using this instrument, we report aerosol extinction in the ultraviolet and near-visible spectral region as a function of chemical composition and structure. We have measured the extinction cross-sections between 360 - 420 nm with 0.5 nm resolution using different sizes and concentrations of polystyrene latex spheres, ammonium sulfate, and Suwannee River fulvic acid. Fitting the real and imaginary part of the refractive index allows the absorption and scattering to be determined.

  4. High resolution humidity, temperature and aerosol profiling with MeteoSwiss Raman lidar

    NASA Astrophysics Data System (ADS)

    Dinoev, Todor; Arshinov, Yuri; Bobrovnikov, Sergei; Serikov, Ilya; Calpini, Bertrand; van den Bergh, Hubert; Parlange, Marc B.; Simeonov, Valentin

    2010-05-01

    Meteorological services rely, in part, on numerical weather prediction (NWP). Twice a day radiosonde observations of water vapor provide the required data for assimilation but this time resolution is insufficient to resolve certain meteorological phenomena. High time resolution temperature profiles from microwave radiometers are available as well but have rather low vertical resolution. The Raman LIDARs are able to provide temperature and humidity profiles with high time and range resolution, suitable for NWP model assimilation and validation. They are as well indispensible tools for continuous aerosol profiling for high resolution atmospheric boundary layer studies. To improve the database available for direct meteorological applications the Swiss meteo-service (MeteoSwiss), the Swiss Federal Institute of Technology in Lausanne (EPFL) and the Swiss National Science Foundation (SNSF) initiated a project to design and build an automated Raman lidar for day and night vertical profiling of tropospheric water vapor with the possibility to further upgrade it with an aerosol and temperature channels. The project was initiated in 2004 and RALMO (Raman Lidar for meteorological observations) was inaugurated in August 2008 at MeteoSwiss aerological station at Payerne. RALMO is currently operational and continuously profiles water vapor mixing ratio, aerosol backscatter ratio and aerosol extinction. The instrument is a fully automated, self-contained, eye-safe Raman lidar operated at 355 nm. Narrow field-of-view multi-telescope receiver and narrow band detection allow day and night-time vertical profiling of the atmospheric humidity. The rotational-vibrational Raman lidar responses from water vapor and nitrogen are spectrally separated by a high-throughput fiber coupled diffraction grating polychromator. The elastic backscatter and pure-rotational Raman lidar responses (PRR) from oxygen and nitrogen are spectrally isolated by a double grating polychromator and are used to

  5. Aerosols and lightning activity: The effect of vertical profile and aerosol type

    NASA Astrophysics Data System (ADS)

    Proestakis, E.; Kazadzis, S.; Lagouvardos, K.; Kotroni, V.; Amiridis, V.; Marinou, E.; Price, C.; Kazantzidis, A.

    2016-12-01

    The Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on board the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite has been utilized for the first time in a study regarding lightning activity modulation due to aerosols. Lightning activity observations, obtained by the ZEUS long range Lightning Detection Network, European Centre for Medium range Weather Forecasts (ECMWF) Convective Available Potential Energy (CAPE) data and Cloud Fraction (CF) retrieved by MODIS on board Aqua satellite have been combined with CALIPSO CALIOP data over the Mediterranean basin and for the period March to November, from 2007 to 2014. The results indicate that lightning activity is enhanced during days characterized by higher Aerosol Optical Depth (AOD) values, compared to days with no lightning. This study contributes to existing studies on the link between lightning activity and aerosols, which have been based just on columnar AOD satellite retrievals, by performing a deeper analysis into the effect of aerosol profiles and aerosol types. Correlation coefficients of R = 0.73 between the CALIPSO AOD and the number of lightning strikes detected by ZEUS and of R = 0.93 between ECMWF CAPE and lightning activity are obtained. The analysis of extinction coefficient values at 532 nm indicates that at an altitudinal range exists, between 1.1 km and 2.9 km, where the values for extinction coefficient of lightning-active and non-lightning-active cases are statistically significantly different. Finally, based on the CALIPSO aerosol subtype classification, we have investigated the aerosol conditions of lightning-active and non-lightning-active cases. According to the results polluted dust aerosols are more frequently observed during non-lightning-active days, while dust and smoke aerosols are more abundant in the atmosphere during the lightning-active days.

  6. Airborne Cavity Ring-Down Measurement of Aerosol Extinction and Scattering During the Aerosol IOP

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Ricci, K.; Provencal, R.; Schmid, B.; Covert, D.; Elleman, R.; Arnott, P.

    2003-01-01

    Large uncertainties in the effects of aerosols on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This paper describes preliminary results from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument designed to address these uncertainties. Cadenza measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. In the past year Cadenza was deployed in the Asian Dust Above Monterey (ADAM) and DOE Aerosol Intensive Operating Period (IOP) field projects. During these flights Cadenza produced measurements of aerosol extinction in the range from 0.2 to 300 Mm-1 with an estimated precision of 0.1 Min-1 for 1550 nm light and 0.2 Mm-1 for 675 nm light. Cadenza data from the ADAM and Aerosol IOP missions compared favorably with data from the other instruments aboard the CIRPAS Twin Otter aircraft and participating in those projects.= We present comparisons between the Cadenza measurements and those friom a TSI nephelometer, Particle Soot Absorption Photometer (PSAP), and the AATS 14 sun-photometer. Measurements of the optical properties of smoke and dust plumes sampled during these campaigns are presented and estimates of heating rates due to these plumes are made.

  7. Light extinction by Secondary Organic Aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-07-01

    Broadband optical cavity spectrometers are maturing as a technology for trace gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulphate particles the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  8. Light extinction by secondary organic aerosol: an intercomparison of three broadband cavity spectrometers

    NASA Astrophysics Data System (ADS)

    Varma, R. M.; Ball, S. M.; Brauers, T.; Dorn, H.-P.; Heitmann, U.; Jones, R. L.; Platt, U.; Pöhler, D.; Ruth, A. A.; Shillings, A. J. L.; Thieser, J.; Wahner, A.; Venables, D. S.

    2013-11-01

    Broadband optical cavity spectrometers are maturing as a technology for trace-gas detection, but only recently have they been used to retrieve the extinction coefficient of aerosols. Sensitive broadband extinction measurements allow explicit separation of gas and particle phase spectral contributions, as well as continuous spectral measurements of aerosol extinction in favourable cases. In this work, we report an intercomparison study of the aerosol extinction coefficients measured by three such instruments: a broadband cavity ring-down spectrometer (BBCRDS), a cavity-enhanced differential optical absorption spectrometer (CE-DOAS), and an incoherent broadband cavity-enhanced absorption spectrometer (IBBCEAS). Experiments were carried out in the SAPHIR atmospheric simulation chamber as part of the NO3Comp campaign to compare the measurement capabilities of NO3 and N2O5 instrumentation. Aerosol extinction coefficients between 655 and 690 nm are reported for secondary organic aerosols (SOA) formed by the NO3 oxidation of β-pinene under dry and humid conditions. Despite different measurement approaches and spectral analysis procedures, the three instruments retrieved aerosol extinction coefficients that were in close agreement. The refractive index of SOA formed from the β-pinene + NO3 reaction was 1.61, and was not measurably affected by the chamber humidity or by aging of the aerosol over several hours. This refractive index is significantly larger than SOA refractive indices observed in other studies of OH and ozone-initiated terpene oxidations, and may be caused by the large proportion of organic nitrates in the particle phase. In an experiment involving ammonium sulfate particles, the aerosol extinction coefficients as measured by IBBCEAS were found to be in reasonable agreement with those calculated using the Mie theory. The results of the study demonstrate the potential of broadband cavity spectrometers for determining the optical properties of aerosols.

  9. Seasonal variability of aerosol vertical profiles over east US and west Europe: GEOS-Chem/APM simulation and comparison with CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoyan; Yu, Fangqun

    2014-04-01

    In this study, we employed 5 years (2007-2011) of the CALIPSO level-3 monthly aerosol extinction product to compare with the GEOS-Chem/APM simulations for the same time period over two major industrial regions (east US and west Europe). The objective is to understand which aerosol types or species significantly determine the vertical profiles by comparing the seasonal variability between the simulations and observations. Our study shows that the model successfully produces the magnitude of aerosol extinction, profile shape, and their seasonal variability observed by CALIPSO over both east US (EUS) and west Europe (WEU). The extinctions below 1 km make up 44-79% to the total, from either the model simulations or satellite retrievals, with larger percentages in winter seasons (62-79%) and smaller percentages in summer seasons (44-57%) associated with the strength of vertical transport. The shape of the vertical profiles has, therefore, a distinct seasonal variability, with a more like quasi-exponential shape in DJF (December, January, and February) and SON (September, October, and November) than in MAM (March, April, and May) and JJA (June, July, and August), which have been discerned from both measurements and simulations. Analysis of modeled aerosol species indicates that secondary particles (SP), containing sulfate, ammonia, nitrate, and secondary organic aerosols (SOAs), predominantly determine the total aerosol vertical profiles while black carbon (BC), primary organic carbon (OC), and sea salt (SS), only account for a small fraction and are also limited near the surface. Mineral dust (DS) contributes more to the total extinction over WEU than over EUS, particularly in MAM, a result of being adjacent to the North Africa desert. Secondary inorganic aerosol (SIA, i.e. sulfate, ammonia, and nitrate) contributes most of the total SP mass in DJF and SON while SOA is particularly important in MAM and JJA when the emissions from leafed plants are active. Our study also

  10. Retrieving the aerosol lidar ratio profile by combining ground- and space-based elastic lidars.

    PubMed

    Feiyue, Mao; Wei, Gong; Yingying, Ma

    2012-02-15

    The aerosol lidar ratio is a key parameter for the retrieval of aerosol optical properties from elastic lidar, which changes largely for aerosols with different chemical and physical properties. We proposed a method for retrieving the aerosol lidar ratio profile by combining simultaneous ground- and space-based elastic lidars. The method was tested by a simulated case and a real case at 532 nm wavelength. The results demonstrated that our method is robust and can obtain accurate lidar ratio and extinction coefficient profiles. Our method can be useful for determining the local and global lidar ratio and validating space-based lidar datasets.

  11. Cavity Attenuated Phase Shift (CAPS) Method for Airborne Aerosol Light Extinction Measurement: Instrument Validation and First Results from Field Deployment

    NASA Astrophysics Data System (ADS)

    Petzold, A.; Perim de Faria, J.; Berg, M.; Bundke, U.; Freedman, A.

    2015-12-01

    Monitoring the direct impact of aerosol particles on climate requires the continuous measurement of aerosol optical parameters like the aerosol extinction coefficient on a regular basis. Remote sensing and ground-based networks are well in place (e.g., AERONET, ACTRIS), whereas the regular in situ measurement of vertical profiles of atmospheric aerosol optical properties remains still an important challenge in quantifying climate change. The European Research Infrastructure IAGOS (In-service Aircraft for a Global Observing System; www.iagos.org) responds to the increasing requests for long-term, routine in situ observational data by using commercial passenger aircraft as measurement platform. However, scientific instrumentation for the measurement of atmospheric constituents requires major modifications before being deployable aboard in-service passenger aircraft. Recently, a compact and robust family of optical instruments based on the cavity attenuated phase shift (CAPS) technique has become available for measuring aerosol light extinction. While this technique was successfully deployed for ground-based atmospheric measurements under various conditions, its suitability for operation aboard aircraft in the free and upper free troposphere still has to be demonstrated. In this work, the modifications of a CAPS PMex instrument for measuring aerosol light extinction on aircraft, the results from subsequent laboratory tests for evaluating the modified instrument prototype, and first results from a field deployment aboard a research aircraft will be covered. In laboratory studies, the instrument showed excellent agreement (deviation < 5%) with theoretical values calculated from Rayleigh scattering cross-sections, when operated on pressurized air and CO2 at ambient and low pressure (~200 hPa). For monodisperse and polydisperse aerosols, reference aerosol extinction coefficients were calculated from measured size distributions and agreed with the CAPS PMex instrument

  12. Altitude Differentiated Aerosol Extinction Over Tenerife (North Atlantic Coast) During ACE-2 by Means of Ground and Airborne Photometry and Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Formenti, P.; Elias, T.; Welton, J.; Diaz, J. P.; Exposito, F.; Schmid, B.; Powell, D.; Holben, B. N.; Smirnov, A.; Andreae, M. O.; hide

    2000-01-01

    Retrievals of spectral aerosol optical depths (tau(sub a)) by means of sun photometers have been undertaken in Tenerife (28 deg 16' N, 16 deg 36' W) during ACE-2 (June-July 1997). Five ground-based sites were located at four different altitudes in the marine boundary layer and in the free troposphere, from 0 to 3570 m asl. The goal of the investigation was to provide estimates of the vertical aerosol extinction over the island, both under clean and turbid conditions. Inversion of spectral tau(sub a) allowed to retrieve size distributions, from which the single scattering albedo omega(sub 0) and the asymmetry factor g could be estimated as a function of altitude. These parameters were combined to calculate aerosol forcing in the column. Emphasis is put on episodes of increased turbidity, which were observed at different locations simultaneously, and attributed to outbreaks of mineral dust from North Africa. Differentiation of tau(sub a) as a function of altitude provided the vertical profile of the extinction coefficient sigma(sub e). For dust outbreaks, aerosol extinction is concentrated in two distinct layers above and below the strong subsidence inversion around 1200 m asl. Vertical profiles of tau(sub a) and sigma(sub e) are shown for July 8. In some occasions, vertical profiles are compared to LIDAR observations, performed both at sea level and in the low free troposphere, and to airborne measurements of aerosol optical depths.

  13. Field Studies of Broadband Aerosol Optical Extinction in the Ultraviolet Spectral Region

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A.; Brock, C. A.; Brown, S. S.

    2013-12-01

    Aerosols influence the Earth's radiative budget by scattering and absorbing incoming solar radiation. The optical properties of aerosols vary as a function of wavelength, but few measurements have reported the wavelength dependence of aerosol extinction cross sections and complex refractive indices. In the case of brown carbon, its wavelength-dependent absorption in the ultraviolet spectral region has been suggested as an important component of aerosol radiative forcing. We describe a new field instrument to measure aerosol optical extinction as a function of wavelength, using cavity enhanced spectroscopy with a broadband light source. The instrument consists of two broadband channels which span the 360-390 and 385-420 nm spectral regions using two light emitting diodes (LED) and a grating spectrometer with charge-coupled device (CCD) detector. We deployed this instrument during the Fire Lab at Missoula Experiment during Fall 2012 to measure biomass burning aerosol, and again during the Southern Oxidant and Aerosol Study in summer 2013 to measure organic aerosol in the Southeastern U.S. In both field experiments, we determined aerosol optical extinction as a function of wavelength and can interpret this together with size distribution and composition measurements to characterize the aerosol optical properties and radiative forcing.

  14. Toward a Combined SAGE II-HALOE Aerosol Climatology: An Evaluation of HALOE Version 19 Stratospheric Aerosol Extinction Coefficient Observations

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.

    2012-01-01

    Herein, the Halogen Occultation Experiment (HALOE) aerosol extinction coefficient data is evaluated in the low aerosol loading period after 1996 as the first necessary step in a process that will eventually allow the production of a combined HALOE/SAGE II (Stratospheric Aerosol and Gas Experiment) aerosol climatology of derived aerosol products including surface area density. Based on these analyses, it is demonstrated that HALOE's 3.46 microns is of good quality above 19 km and suitable for scientific applications above that altitude. However, it is increasingly suspect at lower altitudes and should not be used below 17 km under any circumstances after 1996. The 3.40 microns is biased by about 10% throughout the lower stratosphere due to the failure to clear NO2 but otherwise appears to be a high quality product down to 15 km. The 2.45 and 5.26 micron aerosol extinction coefficient measurements are clearly biased and should not be used for scientific applications after the most intense parts of the Pinatubo period. Many of the issues in the aerosol data appear to be related to either the failure to clear some interfering gas species or doing so poorly. For instance, it is clear that the 3.40micronaerosol extinction coefficient measurements can be improved through the inclusion of an NO2 correction and could, in fact, end up as the highest quality overall HALOE aerosol extinction coefficient measurement. It also appears that the 2.45 and 5.26 micron channels may be improved by updating the Upper Atmosphere Pilot Database which is used as a resource for the removal of gas species otherwise not available from direct HALOE measurements. Finally, a simple model to demonstrate the promise of mixed visible/infrared aerosol extinction coefficient ensembles for the retrieval of bulk aerosol properties demonstrates that a combined HALOE/SAGE II aerosol climatology is feasible and may represent a substantial improvement over independently derived data sets.

  15. Inter-Comparison of ILAS-II Version 1.4 Aerosol Extinction Coefficient at 780 nm with SAGE II, SAGE III, and POAM III Aerosol Data

    NASA Technical Reports Server (NTRS)

    Saitoh, Naoko; Hayashida, S.; Sugita, T.; Nakajima, H.; Yokota, T.; Hayashi, M.; Shiraishi, K.; Kanzawa, H.; Ejiri, M. K.; Irie, H.; hide

    2006-01-01

    The Improved Limb Atmospheric Spectrometer (ILAS) II on board the Advanced Earth Observing Satellite (ADEOS) II observed stratospheric aerosol in visible/near-infrared/infrared spectra over high latitudes in the Northern and Southern Hemispheres. Observations were taken intermittently from January to March, and continuously from April through October, 2003. We assessed the data quality of ILAS-II version 1.4 aerosol extinction coefficients at 780 nm from comparisons with the Stratospheric Aerosol and Gas Experiment (SAGE) II, SAGE III, and the Polar Ozone and Aerosol Measurement (POAM) III aerosol data. At heights below 20 km in the Northern Hemisphere, aerosol extinction coefficients from ILAS-II agreed with those from SAGE II and SAGE III within 10%, and with those from POAM III within 15%. From 20 to 26 km, ILAS-II aerosol extinction coefficients were smaller than extinction coefficients from the other sensors; differences between ILAS-II and SAGE II ranged from 10% at 20 km to 34% at 26 km. ILAS-II aerosol extinction coefficients from 20 to 25 km in February over the Southern Hemisphere had a negative bias (12-66%) relative to SAGE II aerosol data. The bias increased with increasing altitude. Comparisons between ILAS-II and POAM III aerosol extinction coefficients from January to May in the Southern Hemisphere (defined as the non-Polar Stratospheric Cloud (PSC) season ) yielded qualitatively similar results. From June to October (defined as the PSC season ), aerosol extinction coefficients from ILAS-II were smaller than those from POAM III above 17 km, as in the case of the non-PSC season; however, ILAS-II and POAM III aerosol data were within 15% of each other from 12 to 17 km.

  16. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. [Determination of the error of aerosol extinction coefficient measured by DOAS].

    PubMed

    Si, Fu-qi; Liu, Jian-guo; Xie, Pin-hua; Zhang, Yu-jun; Wang, Mian; Liu, Wen-qing; Hiroaki, Kuze; Liu, Cheng; Nobuo, Takeuchi

    2006-10-01

    The method of defining the error of aerosol extinction coefficient measured by differential optical absorption spectroscopy (DOAS) is described. Some factors which could bring errors to result, such as variation of source, integral time, atmospheric turbulence, calibration of system parameter, displacement of system, and back scattering of particles, are analyzed. The error of aerosol extinction coefficient, 0.03 km(-1), is determined by theoretical analysis and practical measurement.

  18. Comparison of MAX-DOAS profiling algorithms during CINDI-2 - Part 1: aerosols

    NASA Astrophysics Data System (ADS)

    Friess, Udo; Hendrick, Francois; Tirpitz, Jan-Lukas; Apituley, Arnoud; van Roozendael, Michel; Kreher, Karin; Richter, Andreas; Wagner, Thomas

    2017-04-01

    The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. CINDI-2 was aiming at assessing the consistency of MAX-DOAS slant column density measurements of tropospheric species (NO2, HCHO, O3, and O4) relevant for the validation of future ESA atmospheric Sentinel missions, through coordinated operation of a large number of DOAS and MAXDOAS instruments from all over the world. An important objective of the campaign was to study the relationship between remote-sensing column and profile measurements of the above species and collocated reference ancillary observations. For this purpose, the CINDI-2 Profiling Task Team (CPTT) was created, involving 22 groups performing aerosol and trace gas vertical profile inversion using dedicated MAX-DOAS profiling algorithms, as well as the teams responsible for ancillary profile and surface concentration measurements (NO2 analysers, NO2 sondes, NO2 and Raman LIDARs, CAPS, Long-Path DOAS, sun photometer, nephelometer, etc). The main purpose of the CPTT is to assess the consistency of the different profiling tools for retrieving aerosol extinction and trace gas vertical profiles through comparison exercises using commonly defined settings and to validate the retrievals with correlative observations. In this presentation, we give an overview of the MAX-DOAS vertical profile comparison results, focusing on the retrieval of aerosol extinction profiles, with the trace gas retrievals being presented in a companion abstract led by F. Hendrick. The performance of the different algorithms is investigated with respect to the variable visibility and cloud conditions encountered during the campaign. The consistency between optimal-estimation-based and parameterized profiling tools is also evaluated for these different conditions, together with the level of agreement

  19. Optical Extinction and Aerosol Hygroscopicity in the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Gordon, T.; Wagner, N.; Lack, D. A.; Richardson, M.; Middlebrook, A. M.; Liao, J.; Murphy, D. M.; Attwood, A. R.; Washenfelder, R. A.; Campuzano Jost, P.; Day, D. A.; Jimenez, J. L.; Carlton, A. M. G.

    2015-12-01

    Most aerosol particles take up water and grow as relative humidity increases, leading to increased optical extinction, reduced visibility, greater aerosol optical depths (AODs), and altered radiative forcing, even while dry particulate mass remains constant. Relative humidity varies greatly temporally, horizontally, and especially vertically. Thus hygroscopicity is a confounding factor when attempting to link satellite-based observations of AOD to surface measurements of particulate mass or to model predictions of aerosol mass concentrations. Airborne observations of aerosol optical, chemical, and microphysical properties were made in the southeastern United States in the daytime in summer 2013 during the NOAA SENEX and NASA SEAC4RS projects. Applying κ-Köhler theory for hygroscopic growth to these data, the inferred hygroscopicity parameter κ for the organic fraction of the aerosol was <0.11. This κ for organics is toward the lower end of values found from laboratory studies of the aerosol formed from oxidation of biogenic precursors and from several field studies in rural environments. The gamma (γ) parameterization is commonly used to describe the change in aerosol extinction as a function of relative humidity. Because this formulation did not fit the airborne data well, a new parameterization was developed that better describes the observations. This new single-parameter κext formulation is physically based and relies upon the well-known approximately linear relationship between particle volume and optical extinction. The fitted parameter, κext, is nonlinearly related to the chemically derived κ parameter used in κ-Köhler theory. The values of κext determined from the airborne measurements are consistent with independent observations at a nearby ground site.

  20. SAGE Aerosol Measurements. Volume 2: 1 January - 31 December 1980

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1986-01-01

    The stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched on February 18, 1979, provides profiles of aerosol extinction at wavelengths of 1.00 and 0.45 micron, ozone concentration, and nitrogen dioxide concentration. Data taken during sunset events in the form of zonal averages and seasonal averages of the aerosol extinction at 1.00 and 0.45 micron, ratios of the aerosol extinction to the molecular extinction at 1.00 micron, and ratios of the aerosol extinction at 0.45 micron to the aerosol extinction at 1.00 micron are presented. The averages for l980 are shown in tables and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by the National Oceanic and Atmospheric Administration (NOAA) for the time and location of each SAGE measurement are averaged and shown in a similar format.

  1. Airborne Aerosol Closure Studies During PRIDE

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Livingston, John M.; Russell, Philip B.; Schmid, Beat; Reid, Jeff

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during June/July of 2000 to study the properties of Saharan dust aerosols transported across the Atlantic Ocean to the Caribbean Islands. During PRIDE, the NASA Ames Research Center six-channel (380 - 1020 nm) airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane alongside a suite of in situ aerosol instruments. The in situ aerosol instrumentation relevant to this paper included a Forward Scattering Spectrometer Probe (FSSP-100) and a Passive Cavity Aerosol Spectrometer Probe (PCASP), covering the radius range of approx. 0.05 to 10 microns. The simultaneous and collocated measurement of multi-spectral aerosol optical depth and in situ particle size distribution data permits a variety of closure studies. For example, vertical profiles of aerosol optical depth obtained during local aircraft ascents and descents can be differentiated with respect to altitude and compared to extinction profiles calculated using the in situ particle size distribution data (and reasonable estimates of the aerosol index of refraction). Additionally, aerosol extinction (optical depth) spectra can be inverted to retrieve estimates of the particle size distributions, which can be compared directly to the in situ size distributions. In this paper we will report on such closure studies using data from a select number of vertical profiles at Cabras Island, Puerto Rico, including measurements in distinct Saharan Dust Layers. Preliminary results show good agreement to within 30% between mid-visible aerosol extinction derived from the AATS-6 optical depth profiles and extinction profiles forward calculated using 60s-average in situ particle size distributions and standard Saharan dust aerosol refractive indices published in the literature. In agreement with tendencies observed in previous studies, our initial results show an underestimate of aerosol extinction calculated based on the in situ size distributions

  2. Selection Algorithm for the CALIPSO Lidar Aerosol Extinction-to-Backscatter Ratio

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Winker, David M.; Vaughan, Mark A.

    2006-01-01

    The extinction-to-backscatter ratio (S(sub a)) is an important parameter used in the determination of the aerosol extinction and subsequently the optical depth from lidar backscatter measurements. We outline the algorithm used to determine Sa for the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) lidar. S(sub a) for the CALIPSO lidar will either be selected from a look-up table or calculated using the lidar measurements depending on the characteristics of aerosol layer. Whenever suitable lofted layers are encountered, S(sub a) is computed directly from the integrated backscatter and transmittance. In all other cases, the CALIPSO observables: the depolarization ratio, delta, the layer integrated attenuated backscatter, beta, and the mean layer total attenuated color ratio, gamma, together with the surface type, are used to aid in aerosol typing. Once the type is identified, a look-up-table developed primarily from worldwide observations, is used to determine the S(sub a) value. The CALIPSO aerosol models include desert dust, biomass burning, background, polluted continental, polluted dust, and marine aerosols.

  3. Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 summertime field campaign, Colorado, USA

    NASA Astrophysics Data System (ADS)

    Dingle, Justin H.; Vu, Kennedy; Bahreini, Roya; Apel, Eric C.; Campos, Teresa L.; Flocke, Frank; Fried, Alan; Herndon, Scott; Hills, Alan J.; Hornbrook, Rebecca S.; Huey, Greg; Kaser, Lisa; Montzka, Denise D.; Nowak, John B.; Reeves, Mike; Richter, Dirk; Roscioli, Joseph R.; Shertz, Stephen; Stell, Meghan; Tanner, David; Tyndall, Geoff; Walega, James; Weibring, Petter; Weinheimer, Andrew

    2016-09-01

    Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) campaign during July-August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex) was deployed to measure βext (at average relative humidity of 20 ± 7 %) of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext / ΔCO) were higher in aged urban air masses compared to fresh air masses by ˜ 50 %. The resulting increase in Δβext / ΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.51 to 2.27 m2 g-1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11-12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.

  4. Small-scale Scheimpflug lidar for aerosol extinction coefficient and vertical atmospheric transmittance detection.

    PubMed

    Sun, Guodong; Qin, Laian; Hou, Zaihong; Jing, Xu; He, Feng; Tan, Fengfu; Zhang, Silong

    2018-03-19

    In this paper, a new prototypical Scheimpflug lidar capable of detecting the aerosol extinction coefficient and vertical atmospheric transmittance at 1 km above the ground is described. The lidar system operates at 532 nm and can be used to detect aerosol extinction coefficients throughout an entire day. Then, the vertical atmospheric transmittance can be determined from the extinction coefficients with the equation of numerical integration in this area. CCD flat fielding of the image data is used to mitigate the effects of pixel sensitivity variation. An efficient method of two-dimensional wavelet transform according to a local threshold value has been proposed to reduce the Gaussian white noise in the lidar signal. Furthermore, a new iteration method of backscattering ratio based on genetic algorithm is presented to calculate the aerosol extinction coefficient and vertical atmospheric transmittance. Some simulations are performed to reduce the different levels of noise in the simulated signal in order to test the precision of the de-noising method and inversion algorithm. The simulation result shows that the root-mean-square errors of extinction coefficients are all less than 0.02 km -1 , and that the relative errors of the atmospheric transmittance between the model and inversion data are below 0.56% for all cases. The feasibility of the instrument and the inversion algorithm have also been verified by an optical experiment. The average relative errors of aerosol extinction coefficients between the Scheimpflug lidar and the conventional backscattering elastic lidar are 3.54% and 2.79% in the full overlap heights of two time points, respectively. This work opens up new possibilities of using a small-scale Scheimpflug lidar system for the remote sensing of atmospheric aerosols.

  5. Profiling Transboundary Aerosols over Taiwan and Assessing Their Radiative Effects

    NASA Technical Reports Server (NTRS)

    Wang, Sheng-Hsiang; Lin, Neng-Huei; Chou, Ming-Dah; Tsay, Si-Chee; Welton, Ellsworth J.; Hsu, N. Christina; Giles, David M.; Liu, Gin-Rong; Holben, Brent N.

    2010-01-01

    A synergistic process was developed to study the vertical distributions of aerosol optical properties and their effects on solar heating using data retrieved from ground-based radiation measurements and radiative transfer simulations. Continuous MPLNET and AERONET observations were made at a rural site in northern Taiwan from 2005 to 2007. The aerosol vertical extinction profiles retrieved from ground-based lidar measurements were categorized into near-surface, mixed, and two-layer transport types, representing 76% of all cases. Fine-mode (Angstrom exponent, alpha, approx.1.4) and moderate-absorbing aerosols (columnar single-scattering albedo approx.0.93, asymmetry factor approx.0.73 at 440 nm wavelength) dominated in this region. The column-integrated aerosol optical thickness at 500 nm (tau(sub 500nm)) ranges from 0.1 to 0.6 for the near-surface transport type, but can be doubled in the presence of upper-layer aerosol transport. We utilize aerosol radiative efficiency (ARE; the impact on solar radiation per unit change of tau(sub 500nm)) to quantify the radiative effects due to different vertical distributions of aerosols. Our results show that the ARE at the top-of-atmosphere (-23 W/ sq m) is weakly sensitive to aerosol vertical distributions confined in the lower troposphere. On the other hand, values of the ARE at the surface are -44.3, -40.6 and -39.7 W/sq m 38 for near-surface, mixed, and two-layer transport types, respectively. Further analyses show that the impact of aerosols on the vertical profile of solar heating is larger for the near-surface transport type than that of two-layer transport type. The impacts of aerosol on the surface radiation and the solar heating profiles have implications for the stability and convection in the lower troposphere.

  6. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richard Ferrare, Connor Flynn, David Turner

    This project focused on: 1) evaluating the performance of the DOE ARM SGP Raman lidar system in measuring profiles of water vapor and aerosols, and 2) the use of the Raman lidar measurements of aerosol and water vapor profiles for assessing the vertical distribution of aerosols and water vapor simulated by global transport models and examining diurnal variability of aerosols and water vapor. The highest aerosol extinction was generally observed close to the surface during the nighttime just prior to sunrise. The high values of aerosol extinction are most likely associated with increased scattering by hygroscopic aerosols, since the correspondingmore » average relative humidity values were above 70%. After sunrise, relative humidity and aerosol extinction below 500 m decreased with the growth in the daytime convective boundary layer. The largest aerosol extinction for altitudes above 1 km occurred during the early afternoon most likely as a result of the increase in relative humidity. The water vapor mixing ratio profiles generally showed smaller variations with altitude between day and night. We also compared simultaneous measurements of relative humidity, aerosol extinction, and aerosol optical thickness derived from the ARM SGP Raman lidar and in situ instruments on board a small aircraft flown routinely over the ARM SGP site. In contrast, the differences between the CARL and IAP aerosol extinction measurements are considerably larger. Aerosol extinction derived from the IAP measurements is, on average, about 30-40% less than values derived from the Raman lidar. The reasons for this difference are not clear, but may be related to the corrections for supermicron scattering and relative humidity that were applied to the IAP data. The investigators on this project helped to set up a major field mission (2003 Aerosol IOP) over the DOE ARM SGP site. One of the goals of the mission was to further evaluate the aerosol and water vapor retrievals from this lidar system

  7. SAGE aerosol measurements. Volume 1: February 21, 1979 to December 31, 1979

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1985-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched on February 18, 1979, provides profiles of aerosol extinction, ozone concentration, and nitrogen dioxide concentration between about 80 N and 80 S. Zonal averages, separated into sunrise and sunset events, and seasonal averages of the aerosol extinction at 1.00 microns and 0.45 microns ratios of the aerosol extinction to the molecular extinction at 1.00 microns, and ratios of the aerosol extinction at 0.45 microns to the aerosol extinction at 1.00 microns are given. The averages for 1979 are shown in tables and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by the National Oceanic and Atmospheric Administration (NOAA) for the time and location of each SAGE measurement are averaged and shown in a similar format. Typical values of the peak aerosol extinction were 0.0001 to 0.0002 km at 1.00 microns depth values for the 1.00 microns channel varied between 0.001 and 0.002 over all latitudes.

  8. Aerosol characteristics inversion based on the improved lidar ratio profile with the ground-based rotational Raman-Mie lidar

    NASA Astrophysics Data System (ADS)

    Ji, Hongzhu; Zhang, Yinchao; Chen, Siying; Chen, He; Guo, Pan

    2018-06-01

    An iterative method, based on a derived inverse relationship between atmospheric backscatter coefficient and aerosol lidar ratio, is proposed to invert the lidar ratio profile and aerosol extinction coefficient. The feasibility of this method is investigated theoretically and experimentally. Simulation results show the inversion accuracy of aerosol optical properties for iterative method can be improved in the near-surface aerosol layer and the optical thick layer. Experimentally, as a result of the reduced insufficiency error and incoherence error, the aerosol optical properties with higher accuracy can be obtained in the near-surface region and the region of numerical derivative distortion. In addition, the particle component can be distinguished roughly based on this improved lidar ratio profile.

  9. Vertical profiles of urban aerosol complex refractive index in the frame of ESQUIF airborne measurements

    NASA Astrophysics Data System (ADS)

    Raut, J.-C.; Chazette, P.

    2007-07-01

    A synergy between lidar, sunphotometer and in situ measurements has been applied to airborne observations performed during the Etude et Simulation de la QUalité de l'air en Ile-de-France (ESQUIF), enabling the retrieval of vertical profiles for the aerosol complex refractive index (ACRI) and single-scattering albedo with a vertical resolution of 200 m over Paris area. The averaged value over the entire planetary boundary layer (PBL) for the ACRI is close to 1.51(±0.02)-i0.017(±0.003) at 532 nm. The single-scattering albedo of the corresponding aerosols is found to be ~0.9 at the same wavelength. A good agreement is found with previous studies for urban aerosols. A comparison of vertical profiles of ACRI with simulations combining in situ measurements and relative humidity (RH) profiles has highlighted a modification in aerosol optical properties linked to their history and the origin of the air mass. The determination of ACRI in the atmospheric column enabled to retrieve vertical profiles of extinction coefficient in accordance with lidar profiles measurements.

  10. Vertical profiles of urban aerosol complex refractive index in the frame of ESQUIF airborne measurements

    NASA Astrophysics Data System (ADS)

    Raut, J.-C.; Chazette, P.

    2008-02-01

    A synergy between lidar, sunphotometer and in situ measurements has been applied to airborne observations performed during the Etude et Simulation de la QUalité de l'air en Ile-de-France (ESQUIF), enabling the retrieval of vertical profiles for the aerosol complex refractive index (ACRI) and single-scattering albedo with a vertical resolution of 200 m over Paris area. The averaged value over the entire planetary boundary layer (PBL) for the ACRI is close to 1.51(±0.02)-i0.017(±0.003) at 532 nm. The single-scattering albedo of the corresponding aerosols is found to be ~0.9 at the same wavelength. A good agreement is found with previous studies for urban aerosols. A comparison of vertical profiles of ACRI with simulations combining in situ measurements and relative humidity (RH) profiles has highlighted a modification in aerosol optical properties linked to their history and the origin of the air mass. The determination of ACRI in the atmospheric column enabled to retrieve vertical profiles of extinction coefficient in accordance with lidar profiles measurements.

  11. Inversion of solar extinction data from the Apollo-Soyuz Test Project Stratospheric Aerosol Measurement (ASTP/SAM) experiment

    NASA Technical Reports Server (NTRS)

    Pepin, T. J.

    1977-01-01

    The inversion methods are reported that have been used to determine the vertical profile of the extinction coefficient due to the stratospheric aerosols from data measured during the ASTP/SAM solar occultation experiment. Inversion methods include the onion skin peel technique and methods of solving the Fredholm equation for the problem subject to smoothing constraints. The latter of these approaches involves a double inversion scheme. Comparisons are made between the inverted results from the SAM experiment and near simultaneous measurements made by lidar and balloon born dustsonde. The results are used to demonstrate the assumptions required to perform the inversions for aerosols.

  12. Relating Aerosol Mass and Optical Depth in the Summertime Continental Boundary Layer

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N.; Middlebrook, A. M.; Attwood, A. R.; Washenfelder, R. A.; Brown, S. S.; McComiskey, A. C.; Gordon, T. D.; Welti, A.; Carlton, A. G.; Murphy, D. M.

    2014-12-01

    Aerosol optical depth (AOD), the column-integrated ambient aerosol light extinction, is determined from satellite and ground-based remote sensing measurements. AOD is the parameter most often used to validate earth system model simulations of aerosol mass. Relating aerosol mass to AOD, however, is problematic due to issues including aerosol water uptake as a function of relative humidity (RH) and the complicated relationship between aerosol physicochemical properties and light extinction. Measurements of aerosol microphysical, chemical, and optical properties help to constrain the relationship between aerosol mass and optical depth because aerosol extinction at ambient RH is a function of the abundance, composition and size distribution of the aerosol. We use vertical profiles of humidity and dry aerosol extinction observed in the southeastern United States (U.S.) to examine the relationship between submicron aerosol mass concentration and extinction at ambient RH. We show that the κ-Köhler parameterization directly, and without additional Mie calculations, describes the change in extinction with varying RH as a function of composition for both aged aerosols typical of the polluted summertime continental boundary layer and the biomass burning aerosols we encountered. We calculate how AOD and the direct radiative effect in the eastern U.S. have likely changed due to trends in aerosol composition in recent decades. We also examine the sensitivity of AOD to the RH profile and to aerosol composition, size distribution and abundance.

  13. Retrieval of atmospheric backscatter and extinction profiles with the aladin airborne demonstrator (A2D)

    NASA Astrophysics Data System (ADS)

    Geiss, Alexander; Marksteiner, Uwe; Lux, Oliver; Lemmerz, Christian; Reitebuch, Oliver; Kanitz, Thomas; Straume-Lindner, Anne Grete

    2018-04-01

    By the end of 2017, the European Space Agency (ESA) will launch the Atmospheric laser Doppler instrument (ALADIN), a direct detection Doppler wind lidar operating at 355 nm. An important tool for the validation and optimization of ALADIN's hardware and data processors for wind retrievals with real atmospheric signals is the ALADIN airborne demonstrator A2D. In order to be able to validate and test aerosol retrieval algorithms from ALADIN, an algorithm for the retrieval of atmospheric backscatter and extinction profiles from A2D is necessary. The A2D is utilizing a direct detection scheme by using a dual Fabry-Pérot interferometer to measure molecular Rayleigh signals and a Fizeau interferometer to measure aerosol Mie returns. Signals are captured by accumulation charge coupled devices (ACCD). These specifications make different steps in the signal preprocessing necessary. In this paper, the required steps to retrieve aerosol optical products, i. e. particle backscatter coefficient βp, particle extinction coefficient αp and lidar ratio Sp from A2D raw signals are described.

  14. SAGE 1 and SAM 2 measurements of 1 micron aerosol extinction in the free troposphere

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Farrukh, U. O.; Wang, P. H.; Deepak, A.

    1988-01-01

    The SAGE 1 and SAM 2 satellite sensors were designed to measure, with global coverage, the 1 micron extinction produced by the stratospheric aerosol. In the absence of high altitude cloud, similar measurements may be made for the free tropospheric aerosol. Median extinction values in the Northern Hemisphere, for altitudes between 5 and 10 km, are found to be one-half to one order of magnitude greater than values at corresponding latitudes in the Southern Hemisphere. In addition, a seasonal increase by a factor of 1.5 yields 2 is observed in both hemispheres in local spring and summer. Following major volcanic eruptions, a long-lived enhancement of the aerosol extinction is observed for altitudes above 5 km.

  15. Aerosol impacts on visible light extinction in the atmosphere of Mexico City.

    PubMed

    Eidels-Dubovoi, Silvia

    2002-03-27

    Eleven diurnal aerosol visible light absorption and scattering patterns were obtained from measurements done with an aethalometer and an integrating nephelometer during 28 February-10 March 1997 at two different sites in the Mexico City basin. Both measurement sites, the Merced site affected by regional and urban-scale aerosol and the Pedregal site dominated by regional-scale aerosol, showed a variety of diurnal light absorption and scattering patterns. For the majority of the 11 studied days, the highest absorption peaks appeared in the early morning, 07.00-09.30 h while those of scattering appeared later, 09.30-11.00 h. The earlier absorption peaks could be attributed to the elevated elemental carbon vehicular emissions during the heavy traffic hours whereas the later scattering peaks could be attributed to secondary aerosols formed photochemically in the atmosphere. During the period examined, the Pedregal site exhibited on the average a lower aerosol scattering and a higher aerosol absorption contribution to the total aerosol visible light extinction and a better visibility than that of the Merced site. Hence, the impact of aerosol absorption on the visibility degradation due to aerosols was greater at the less hazy Pedregal site. The overall 11-day aerosol visibility average of 20.9 km found at La Merced site, was only 9.4 km lower than that of 30.3 km found at the Pedregal site. This small aerosol visibility difference, of the order of the standard deviation, led to the conclusion that besides the regional-scale aerosol impact, the urban-scale aerosol impact on aerosol visible light extinction is very similar at La Merced and Pedregal sites.

  16. Potential of polarization lidar to provide profiles of CCN- and INP-relevant aerosol parameters

    NASA Astrophysics Data System (ADS)

    Mamouri, R. E.; Ansmann, A.

    2015-12-01

    We investigate the potential of polarization lidar to provide vertical profiles of aerosol parameters from which cloud condensation nucleus (CCN) and ice nucleating particle (INP) number concentrations can be estimated. We show that height profiles of number concentrations of aerosol particles with radius > 50 nm (APC50, reservoir of favorable CCN) and with radius > 250 nm (APC250, reservoir of favorable INP), as well as profiles of the aerosol particle surface area concentration (ASC, used in INP parameterization) can be retrieved from lidar-derived aerosol extinction coefficients (AEC) with relative uncertainties of a factor of around 2 (APC50), and of about 25-50 % (APC250, ASC). Of key importance is the potential of polarization lidar to identify mineral dust particles and to distinguish and separate the aerosol properties of basic aerosol types such as mineral dust and continental pollution (haze, smoke). We investigate the relationship between AEC and APC50, APC250, and ASC for the main lidar wavelengths of 355, 532 and 1064 nm and main aerosol types (dust, pollution, marine). Our study is based on multiyear Aerosol Robotic Network (AERONET) photometer observations of aerosol optical thickness and column-integrated particle size distribution at Leipzig, Germany, and Limassol, Cyprus, which cover all realistic aerosol mixtures of continental pollution, mineral dust, and marine aerosol. We further include AERONET data from field campaigns in Morocco, Cabo Verde, and Barbados, which provide pure dust and pure marine aerosol scenarios. By means of a simple relationship between APC50 and the CCN-reservoir particles (APCCCN) and published INP parameterization schemes (with APC250 and ASC as input) we finally compute APCCCN and INP concentration profiles. We apply the full methodology to a lidar observation of a heavy dust outbreak crossing Cyprus with dust up to 8 km height and to a case during which anthropogenic pollution dominated.

  17. Minimum aerosol layer detection sensitivities and their subsequent impacts on aerosol optical thickness retrievals in CALIPSO level 2 data products

    NASA Astrophysics Data System (ADS)

    Toth, Travis D.; Campbell, James R.; Reid, Jeffrey S.; Tackett, Jason L.; Vaughan, Mark A.; Zhang, Jianglong; Marquis, Jared W.

    2018-01-01

    Due to instrument sensitivities and algorithm detection limits, level 2 (L2) Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) 532 nm aerosol extinction profile retrievals are often populated with retrieval fill values (RFVs), which indicate the absence of detectable levels of aerosol within the profile. In this study, using 4 years (2007-2008 and 2010-2011) of CALIOP version 3 L2 aerosol data, the occurrence frequency of daytime CALIOP profiles containing all RFVs (all-RFV profiles) is studied. In the CALIOP data products, the aerosol optical thickness (AOT) of any all-RFV profile is reported as being zero, which may introduce a bias in CALIOP-based AOT climatologies. For this study, we derive revised estimates of AOT for all-RFV profiles using collocated Moderate Resolution Imaging Spectroradiometer (MODIS) Dark Target (DT) and, where available, AErosol RObotic NEtwork (AERONET) data. Globally, all-RFV profiles comprise roughly 71 % of all daytime CALIOP L2 aerosol profiles (i.e., including completely attenuated profiles), accounting for nearly half (45 %) of all daytime cloud-free L2 aerosol profiles. The mean collocated MODIS DT (AERONET) 550 nm AOT is found to be near 0.06 (0.08) for CALIOP all-RFV profiles. We further estimate a global mean aerosol extinction profile, a so-called noise floor, for CALIOP all-RFV profiles. The global mean CALIOP AOT is then recomputed by replacing RFV values with the derived noise-floor values for both all-RFV and non-all-RFV profiles. This process yields an improvement in the agreement of CALIOP and MODIS over-ocean AOT.

  18. Six-channel multi-wavelength polarization Raman lidar for aerosol and water vapor profiling.

    PubMed

    Wang, Zhaofei; Mao, Jiandong; Li, Juan; Zhao, Hu; Zhou, Chunyan; Sheng, Hongjiang

    2017-07-10

    Aerosols and water vapor are important atmospheric components, and have significant effects on both atmospheric energy conversion and climate formation. They play the important roles in balancing the radiation budget between the atmosphere and Earth, while water vapor also directly affects rainfall and other weather processes. To further research atmospheric aerosol optical properties and water vapor content, an all-time six-channel multi-wavelength polarization Raman lidar has been developed at Beifang University of Nationalities. In addition to 1064, 532, and 355 nm Mie scattering channels, the lidar has a polarization channel for 532 nm return signals, a 660 nm water vapor channel, and a 607 nm nitrogen detection channel. Experiments verified the lidar's feasibility and return signals from six channels were detected. Using inversion algorithms, extinction coefficient profiles at 1064, 532 and 355 nm, Ångström exponent profiles, depolarization ratio profiles, and water vapor mixing ratio profiles were all obtained. The polarization characteristics and water vapor content of cirrus clouds, the polarization characteristics of dusty weather, and the water vapor profiles over different days were also analyzed. Results show that the lidar has the full-time detection capability for atmospheric aerosol optical properties and water vapor profiles, and real-time measurements of aerosols and water vapor over the Yinchuan area were realized, providing important information for studying the environmental quality and climate change in this area.

  19. Open-path, closed-path and reconstructed aerosol extinction at a rural site.

    PubMed

    Gordon, Timothy D; Prenni, Anthony J; Renfro, James R; McClure, Ethan; Hicks, Bill; Onasch, Timothy B; Freedman, Andrew; McMeeking, Gavin R; Chen, Ping

    2018-04-09

    The Handix Scientific Open-Path Cavity Ringdown Spectrometer (OPCRDS) was deployed during summer 2016 in Great Smoky Mountains National Park (GRSM). Extinction coefficients from the relatively new OPCRDS and from a more well-established extinction instrument agreed to within 7%. Aerosol hygroscopic growth (f(RH)) was calculated from the ratio of ambient extinction measured by the OPCRDS to dry extinction measured by a closed-path extinction monitor (Aerodyne's Cavity Attenuated Phase Shift Particulate Matter Extinction Monitor, CAPS PMex). Derived hygroscopicity (RH < 95%) from this campaign agreed with data from 1995 at the same site and time of year, which is noteworthy given the decreasing trend for organics and sulfate in the eastern U.S. However, maximum f(RH) values in 1995 were less than half as large as those recorded in 2016-possibly due to nephelometer truncation losses in 1995. Two hygroscopicity parameterizations were investigated using high time resolution OPCRDS+CAPS PMex data, and the K ext model was more accurate than the γ model. Data from the two ambient optical instruments, the OPCRDS and the open-path nephelometer, generally agreed; however, significant discrepancies between ambient scattering and extinction were observed, apparently driven by a combination of hygroscopic growth effects, which tend to increase nephelometer truncation losses and decrease sensitivity to the wavelength difference between the two instruments as a function of particle size. There was not a statistically significant difference in the mean reconstructed extinction values obtained from the original and the revised IMPROVE (Interagency Monitoring of Protected Visual Environments) equations. On average IMPROVE reconstructed extinction was ~25% lower than extinction measured by the OPCRDS, which suggests that the IMPROVE equations and 24-hr aerosol data are moderately successful in estimating current haze levels at GRSM. However, this conclusion is limited by the coarse

  20. SAGE II aerosol extinction and scattering data from balloon-borne photography

    NASA Technical Reports Server (NTRS)

    Ackerman, M.; Lippens, G.; Chu, W.; De Muer, D.

    1987-01-01

    Earth limb radiance and extinction near sunset have been observed from a balloon-borne gondola nearly simultaneously and on air masses close to those probed by the SAGE II instrumentation on April 22, 1985. The results show the importance of accuracy of the altitude determination on the aerosol measurements. They indicate an important altitude dependence of the stratospheric aerosol granulometry in agreement with SAGE II results.

  1. Aerosol properties from spectral extinction and backscatter estimated by an inverse Monte Carlo method.

    PubMed

    Ligon, D A; Gillespie, J B; Pellegrino, P

    2000-08-20

    The feasibility of using a generalized stochastic inversion methodology to estimate aerosol size distributions accurately by use of spectral extinction, backscatter data, or both is examined. The stochastic method used, inverse Monte Carlo (IMC), is verified with both simulated and experimental data from aerosols composed of spherical dielectrics with a known refractive index. Various levels of noise are superimposed on the data such that the effect of noise on the stability and results of inversion can be determined. Computational results show that the application of the IMC technique to inversion of spectral extinction or backscatter data or both can produce good estimates of aerosol size distributions. Specifically, for inversions for which both spectral extinction and backscatter data are used, the IMC technique was extremely accurate in determining particle size distributions well outside the wavelength range. Also, the IMC inversion results proved to be stable and accurate even when the data had significant noise, with a signal-to-noise ratio of 3.

  2. Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

    2016-07-01

    The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

  3. Vertical profiles of fine and coarse aerosol particles over Cyprus: Comparison between in-situ drone measurements and remote sensing observations

    NASA Astrophysics Data System (ADS)

    Mamali, Dimitra; Marinou, Eleni; Pikridas, Michael; Kottas, Michael; Binietoglou, Ioannis; Kokkalis, Panagiotis; Tsekeri, Aleksandra; Amiridis, Vasilis; Sciare, Jean; Keleshis, Christos; Engelmann, Ronny; Ansmann, Albert; Russchenberg, Herman W. J.; Biskos, George

    2017-04-01

    Vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) measurements were compared to airborne dried optical particle counter (OPC MetOne; Model 212) measurements during the INUIT-BACCHUS-ACTRIS campaign. The campaign took place in April 2016 and its main focus was the study of aerosol dust particles. During the campaign the NOA Polly-XT Raman lidar located at Nicosia (35.08° N, 33.22° E) was providing round-the-clock vertical profiles of aerosol optical properties. In addition, an unmanned aerial vehicle (UAV) carrying an OPC flew on 7 days during the first morning hours. The flights were performed at Orounda (35.1018° N, 33.0944° E) reaching altitudes of 2.5 km a.s.l, which allows comparison with a good fraction of the recorded lidar data. The polarization lidar photometer networking method (POLIPHON) was used for the estimation of the fine (non-dust) and coarse (dust) mode aerosol mass concentration profiles. This method uses as input the particle backscatter coefficient and the particle depolarization profiles of the lidar at 532 nm wavelength and derives the aerosol mass concentration. The first step in this approach makes use of the lidar observations to separate the backscatter and extinction contributions of the weakly depolarizing non-dust aerosol components from the contributions of the strongly depolarizing dust particles, under the assumption of an externally mixed two-component aerosol. In the second step, sun photometer retrievals of the fine and the coarse modes aerosol optical thickness (AOT) and volume concentration are used to calculate the associated concentrations from the extinction coefficients retrieved from the lidar. The estimated aerosol volume concentrations were converted into mass concentration with an assumption for the bulk aerosol density, and compared with the OPC measurements. The first results show agreement within the experimental uncertainty. This project received funding from the

  4. Applications of Sunphotometry to Aerosol Extinction and Surface Anisotropy

    NASA Technical Reports Server (NTRS)

    Tsay, S. C.; Holben, B. N.; Privette, J. L.

    2005-01-01

    Support cost-sharing of a newly developed sunphotometer in field deployment for aerosol studies. This is a cost-sharing research to deploy a newly developed sun-sky-surface photometer for studying aerosol extinction and surface anisotropy at the ARM SGP, TWP, and NSA-AAO CART sites and in many field campaigns. Atmospheric aerosols affect the radiative energy balance of the Earth, both directly by perturbing the incoming/outgoing radiation fields and indirectly by influencing the properties/processes of clouds and reactive greenhouse gases. The surface bidirectional reflectance distribution function (BRDF) also plays a crucial role in the radiative energy balance, since the BRDF is required to determine (1) the spectral and spectrally-averaged surface albedo, and (2) the top-of-the-atmosphere (TOA) angular distribution of radiance field. Therefore, the CART sites provide an excellent, albeit unique, opportunity to collect long-term climatic data in characterizing aerosol properties and various types of surface anisotropy.

  5. The Cloud-Aerosol Transport System (CATS): A New Lidar for Aerosol and Cloud Profiling from the International Space Station

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; McGill, Mathew J.; Yorks. John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

    2012-01-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064,532,355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time (NRT) data capability ofthe ISS will enable CATS to support operational applications such as aerosol and air quality forecasting and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a

  6. Lidar characterizations of atmospheric aerosols and clouds

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Burton, S. P.

    2017-12-01

    Knowledge of the vertical profile, composition, concentration, and size distribution of aerosols is required to quantify the impacts of aerosols on human health, global and regional climate, clouds and precipitation. In particular, radiative forcing due to anthropogenic aerosols is the most uncertain part of anthropogenic radiative forcing, with aerosol-cloud interactions (ACI) as the largest source of uncertainty in current estimates of global radiative forcing. Improving aerosol transport model predictions of the vertical profile of aerosol optical and microphysical characteristics is crucial for improving assessments of aerosol radiative forcing. Understanding how aerosols and clouds interact is essential for investigating the aerosol indirect effect and ACI. Through its ability to provide vertical profiles of aerosol and cloud distributions as well as important information regarding the optical and physical properties of aerosols and clouds, lidar is a crucial tool for addressing these science questions. This presentation describes how surface, airborne, and satellite lidar measurements have been used to address these questions, and in particular how High Spectral Resolution Lidar (HSRL) measurements provide profiles of aerosol properties (backscatter, extinction, depolarization, concentration, size) important for characterizing radiative forcing. By providing a direct measurement of aerosol extinction, HSRL provides more accurate aerosol measurement profiles and more accurate constraints for models than standard retrievals from elastic backscatter lidar, which loses accuracy and precision at lower altitudes due to attenuation from overlying layers. Information regarding particle size and abundance from advanced lidar retrievals provides better proxies for cloud-condensation-nuclei (CCN), which are required for assessing aerosol-cloud interactions. When combined with data from other sensors, advanced lidar measurements can provide information on aerosol and

  7. Aerosol profiling using the ceilometer network of the German Meteorological Service

    NASA Astrophysics Data System (ADS)

    Flentje, H.; Heese, B.; Reichardt, J.; Thomas, W.

    2010-08-01

    The German Meteorological Service (DWD) operates about 52 lidar ceilometers within its synoptic observations network, covering Germany. These affordable low-power lidar systems provide spatially and temporally high resolved aerosol backscatter profiles which can operationally provide quasi 3-D distributions of particle backscatter intensity. Intentionally designed for cloud height detection, recent significant improvements allow following the development of the boundary layer and to detect denser particle plumes in the free tropospere like volcanic ash, Saharan dust or fire smoke. Thus the network builds a powerful aerosol plume alerting and tracking system. If auxiliary aerosol information is available, the particle backscatter coefficient, the extinction coefficient and even particle mass concentrations may be estimated, with however large uncertainties. Therefore, large synergistic benefit is achieved if the ceilometers are linked to existing lidar networks like EARLINET or integrated into WMO's envisioined Global Aerosol Lidar Observation Network GALION. To this end, we demonstrate the potential and limitations of ceilometer networks by means of three representative aerosol episodes over Europe, namely Sahara dust, Mediterranean fire smoke and, more detailed, the Icelandic Eyjafjoll volcano eruption from mid April 2010 onwards. The DWD (Jenoptik CHM15k) lidar ceilometer network tracked the Eyjafjoll ash layers over Germany and roughly estimated peak extinction coefficients and mass concentrations on 17 April of 4-6(± 2) 10-4 m-1 and 500-750(± 300) μg/m-3, respectively, based on co-located aerosol optical depth, nephelometer (scattering coefficient) and particle mass concentration measurements. Though large, the uncertainties are small enough to let the network suit for example as aviation advisory tool, indicating whether the legal flight ban threshold of presently 2 mg/m3 is imminent to be exceeded.

  8. Characteristics of aerosol vertical profiles in Tsukuba, Japan, and their impacts on the evolution of the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Aoyagi, Toshinori; Nishizawa, Tomoaki

    2018-05-01

    Vertical profiles of the aerosol physical and optical properties, with a focus on seasonal means and on transport events, were investigated in Tsukuba, Japan, by a synergistic remote sensing method that uses lidar and sky radiometer data. The retrieved aerosol vertical profiles of the springtime mean and five transport events were input to our developed one-dimensional atmospheric model, and the impacts of the aerosol vertical profiles on the evolution of the atmospheric boundary layer (ABL) were studied by numerical sensitivity experiments. The characteristics of the aerosol vertical profiles in Tsukuba are as follows: (1) the retrieval results in the spring showed that aerosol optical thickness at 532 nm in the free atmosphere (FA) was 0.13, greater than 0.08 in the ABL owing to the frequent occurrence of transported aerosols in the FA. In other seasons, optical thickness in the FA was almost the same as that in the ABL. (2) The aerosol optical and physical properties in the ABL showed a dependency on the extinction coefficient. With an increase in the extinction coefficient from 0.00 to 0.24 km-1, the Ångström exponent increased from 0.0 to 2.0, the single-scattering albedo increased from 0.87 to 0.99, and the asymmetry factor decreased from 0.75 to 0.50. (3) The large variability in the physical and optical properties of aerosols in the FA were attributed to transport events, during which the transported aerosols consisted of varying amounts of dust and smoke particles depending on where they originated (China, Mongolia, or Russia). The results of the numerical sensitivity experiments using the aerosol vertical profiles of the springtime mean and five transport events in the FA are as follows: (1) numerical sensitivity experiments based on simulations conducted with and without aerosols showed that aerosols caused the net downward radiation and the sensible and latent heat fluxes at the surface to decrease. The decrease in temperature in the ABL (-0.2 to -0

  9. SAGE aerosol measurements. Volume 3: January 1, 1981 to November 18, 1981

    NASA Technical Reports Server (NTRS)

    Mccormick, M. Patrick

    1987-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) satellite system, launched February 18, 1979, obtained profiles of aerosol extinction at 1.00 micron and 0.45 micron ozone concentration, and nitrogen dioxide concentration. Data taken during sunset events are presented in the form of zonal and seasonal averages of aerosol extinction of 1.00 micron and 0.45 micron, ratios of aerosol extinction to molecular extinction at 1.00 micron and ratios of aerosol extinction at 0.45 micron to aerosol extinction at 1.00 micron. Averages for 1981 are shown in tables, and in profile and contour plots (as a function of altitude and latitude). In addition, temperature data provided by NOAA for the time and location of each SAGE measurement are averaged and shown in a similar format. The stratospheric aerosol distribution for 1981 shows effects of volcanically injected material from eruptions of Ulawun, Alaid, and Pagan. Peak values of aerosol extinction at 0.45 micron and 1.00 micron were 2 to 4 times higher than typical peak values observed during near background conditions. Stratospheric aerosol optical depth values at 1.00 microns increased by a factor of about 2 from near background levels in regions of volcanic activity. During the year, these values ranged from between 0.001 and 0.006. The largest were near the location of a recent eruption. The distribution of the ratio of aerosol to molecular extinction at 1.00 microns also showed that maximum values are found in the vicinity of an eruption. These maximums varied in altitude, but remained below a height of about 25 km. No attempt has been made to give detailed explanations or interpretations of these data. The intent is to provide, in a ready-to-use visual format, representative zonal and seasonal averages of aerosol extinction data for the third calendar year of the SAGE data set to facilitate atmospheric and climatic studies.

  10. MAESTRO Measurements of Atmospheric Aerosol

    NASA Astrophysics Data System (ADS)

    McElroy, Tom; Drummond, James; Zou, Jason

    2014-05-01

    MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) is now in its 11th year on orbit as part of the Atmospheric Chemistry Experiment on the Canadian Space Agency's SCISAT satellite. MAESTRO data analysis has been dogged by a deficiency in accurate timing between the measurements made by the partner instrument, the ACE-FTS (Atmospheric Chemistry Experiment, Fourier Transform Spectrometer), that provides the atmospheric pressure-temperature profile and observation tangent altitudes used in the MAESTRO data analysis. Attempts have been made to use apparent air column density and oxygen A-band absorption as a mechanism to line up the tangent heights, but to no avail. A new product is now being produced, based on matching the modeled ozone slant columns from the ACE-FTS retrievals with the MAESTRO slant column measurements. The approach is very promising and indicates that a valuable product from the MAESTRO wavelength-dependent aerosol extinction likely result. The usefulness of the profile matching technique will be demonstrated and some aerosol absorption profiles will be presented in comparison with measurements made by the ACE Imager aerosol profile results. While the process optimizes the comparison between ACE-FTS ozone profile data and that from MAESTRO, it does not detract from the higher vertical resolution information provided by MAESTRO.

  11. LASE measurements of aerosols and water vapor during TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard A.; Ismail, Syed; Browell, Edward V.; Brackett, Vincent G.; Kooi, Susan A.; Clayton, Marian B.; Melfi, Harvey; Whiteman, David N.; Schwenner, Geary; Evans, Keith D.; hide

    1998-01-01

    The TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment) intensive field campaign was designed to reduce uncertainties in estimates of the effects of anthropogenic aerosols on climate by measuring direct radiative effects and the optical, physical, and chemical properties of aerosols [1]. TARFOX was conducted off the East Coast of the United States between July 10-31, 1996. Ground, aircraft, and satellite-based sensors measured the sensitivity of radiative fields at various atmospheric levels to aerosol optical properties (i.e., optical thickness, phase function, single-scattering albedo) and to the vertical profile of aerosols. The LASE (Lidar Atmospheric Sensing Experiment) instrument, which was flown on the NASA ER-2 aircraft, measured vertical profiles of total scattering ratio and water vapor during a series of 9 flights. These profiles were used in real-time to help direct the other aircraft to the appropriate altitudes for intensive sampling of aerosol layers. We have subsequently used the LASE aerosol data to derive aerosol backscattering and extinction profiles. Using these aerosol extinction profiles, we derived estimates of aerosol optical thickness (AOT) and compared these with measurements of AOT from both ground and airborne sun photometers and derived from the ATSR-2 (Along Track and Scanning Radiometer 2) sensor on ERS-2 (European Remote Sensing Satellite-2). We also used the water vapor mixing ratio profiles measured simultaneously by LASE to derive precipitable water vapor and compare these to ground based measurements.

  12. An Aerosol Extinction-to-Backscatter Ratio Database Derived from the NASA Micro-Pulse Lidar Network: Applications for Space-based Lidar Observations

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Spinhime, James D.; Berkoff, Timothy A.; Holben, Brent; Tsay, Si-Chee; Bucholtz, Anthony

    2004-01-01

    Backscatter lidar signals are a function of both backscatter and extinction. Hence, these lidar observations alone cannot separate the two quantities. The aerosol extinction-to-backscatter ratio, S, is the key parameter required to accurately retrieve extinction and optical depth from backscatter lidar observations of aerosol layers. S is commonly defined as 4*pi divided by the product of the single scatter albedo and the phase function at 180-degree scattering angle. Values of S for different aerosol types are not well known, and are even more difficult to determine when aerosols become mixed. Here we present a new lidar-sunphotometer S database derived from Observations of the NASA Micro-Pulse Lidar Network (MPLNET). MPLNET is a growing worldwide network of eye-safe backscatter lidars co-located with sunphotometers in the NASA Aerosol Robotic Network (AERONET). Values of S for different aerosol species and geographic regions will be presented. A framework for constructing an S look-up table will be shown. Look-up tables of S are needed to calculate aerosol extinction and optical depth from space-based lidar observations in the absence of co-located AOD data. Applications for using the new S look-up table to reprocess aerosol products from NASA's Geoscience Laser Altimeter System (GLAS) will be discussed.

  13. The Cloud-Aerosol Transport System (CATS): a New Lidar for Aerosol and Cloud Profiling from the International Space Station

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; McGill, Matthew J.; Yorks, John E.; Hlavka, Dennis L.; Hart, William D.; Palm, Stephen P.; Colarco, Peter R.

    2011-01-01

    Spaceborne lidar profiling of aerosol and cloud layers has been successfully implemented during a number of prior missions, including LITE, ICESat, and CALIPSO. Each successive mission has added increased capability and further expanded the role of these unique measurements in wide variety of applications ranging from climate, to air quality, to special event monitoring (ie, volcanic plumes). Many researchers have come to rely on the availability of profile data from CALIPSO, especially data coincident with measurements from other A-Train sensors. The CALIOP lidar on CALIPSO continues to operate well as it enters its fifth year of operations. However, active instruments have more limited lifetimes than their passive counterparts, and we are faced with a potential gap in lidar profiling from space if the CALIOP lidar fails before a new mission is operational. The ATLID lidar on EarthCARE is not expected to launch until 2015 or later, and the lidar component of NASA's proposed Aerosols, Clouds, and Ecosystems (ACE) mission would not be until after 2020. Here we present a new aerosol and cloud lidar that was recently selected to provide profiling data from the International Space Station (ISS) starting in 2013. The Cloud-Aerosol Transport System (CATS) is a three wavelength (1064, 532, 355 nm) elastic backscatter lidar with HSRL capability at 532 nm. Depolarization measurements will be made at all wavelengths. The primary objective of CATS is to continue the CALIPSO aerosol and cloud profile data record, ideally with overlap between both missions and EarthCARE. In addition, the near real time data capability of the ISS will enable CATS to support operational applications such as air quality and special event monitoring. The HSRL channel will provide a demonstration of technology and a data testbed for direct extinction retrievals in support of ACE mission development. An overview of the instrument and mission will be provided, along with a summary of the science

  14. Electronic cigarette solutions and resultant aerosol profiles.

    PubMed

    Herrington, Jason S; Myers, Colton

    2015-10-30

    Electronic cigarettes (e-cigarettes) are growing in popularity exponentially. Despite their ever-growing acceptance, their aerosol has not been fully characterized. The current study focused on evaluating e-cigarette solutions and their resultant aerosol for potential differences. A simple sampling device was developed to draw e-cigarette aerosol into a multi-sorbent thermal desorption (TD) tube, which was then thermally extracted and analyzed via a gas chromatography (GC) mass spectrometry (GC-MS) method. This novel application provided detectable levels of over one hundred fifteen volatile organic compounds (VOCs) and semivolatile organic compounds (SVOCs) from a single 40mL puff. The aerosol profiles from four commercially available e-cigarettes were compared to their respective solution profiles with the same GC-MS method. Solution profiles produced upwards of sixty four unidentified and identified (some only tentatively) constituents and aerosol profiles produced upwards of eighty two compounds. Results demonstrated distinct analyte profiles between liquid and aerosol samples. Most notably, formaldehyde, acetaldehyde, acrolein, and siloxanes were found in the aerosol profiles; however, these compounds were never present in the solutions. These results implicate the aerosolization process in the formation of compounds not found in solutions; have potential implications for human health; and stress the need for an emphasis on electronic cigarette aerosol testing. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

  15. Extinction-to-Backscatter Ratios of Lofted Aerosol Layers Observed During the First Three Months of CALIPSO Measurements

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Vaughan, Mark A.; Liu, Zhaoyan; Hu, Yongxiang; Reagan, John A.; Winker, David M.

    2007-01-01

    Case studies from the first three months of the Cloud and Aerosol Lidar and Infrared Pathfinder Spaceborne Observations (CALIPSO) measurements of lofted aerosol layers are analyzed using transmittance [Young, 1995] and two-wavelength algorithms [Vaughan et al., 2004] to determine the aerosol extinction-to-backscatter ratios at 532 and 1064 nm. The transmittance method requires clear air below the layer so that the transmittance through the layer can be determined. Suitable scenes are selected from the browse images and clear air below features is identified by low 532 nm backscatter signal and confirmed by low depolarization and color ratios. The transmittance and two-wavelength techniques are applied to a number of lofted layers and the extinction-to-backscatter ratios are compared with values obtained from the CALIPSO aerosol models [Omar et al., 2004]. The results obtained from these studies are used to adjust the aerosol models and develop observations based extinction-to-backscatter ratio look-up tables and phase functions. Values obtained by these techniques are compared to Sa determinations using other independent methods with a goal of developing probability distribution functions of aerosol type-specific extinction to backscatter ratios. In particular, the results are compared to values determined directly by the High Spectral Resolution Lidar (HSRL) during the CALIPSO CloudSat Validation Experiments (CCVEX) and Sa determined by the application of the two-wavelength lidar Constrained Ratio Aerosol Model-fit (CRAM) retrieval approach [Cattrall et al., 2005; Reagan et al., 2004] to the HSRL data. The results are also compared to values derived using the empirical relationship between the multiple-scattering fraction and the linear depolarization ratio by using Monte Carlo simulations of water clouds [Hu et al., 2006].

  16. Chemical composition of aerosol particles and light extinction apportionment before and during the heating season in Beijing, China

    NASA Astrophysics Data System (ADS)

    Wang, Qingqing; Sun, Yele; Jiang, Qi; Du, Wei; Sun, Chengzhu; Fu, Pingqing; Wang, Zifa

    2015-12-01

    Despite extensive efforts into characterization of the sources and formation mechanisms of severe haze pollution in the megacity of Beijing, the response of aerosol composition and optical properties to coal combustion emissions in the heating season remain poorly understood. Here we conducted a 3 month real-time measurement of submicron aerosol (PM1) composition by an Aerosol Chemical Speciation Monitor and particle light extinction by a Cavity Attenuated Phase Shift extinction monitor in Beijing, China, from 1 October to 31 December 2012. The average (±σ) PM1 concentration was 82.4 (±73.1) µg/m3 during the heating period (HP, 15 November to 31 December), which was nearly 50% higher than that before HP (1 October to 14 November). While nitrate and secondary organic aerosol (SOA) showed relatively small changes, organics, sulfate, and chloride were observed to have significant increases during HP, indicating the dominant impacts of coal combustion sources on these three species. The relative humidity-dependent composition further illustrated an important role of aqueous-phase processing for the sulfate enhancement during HP. We also observed great increases of hydrocarbon-like OA (HOA) and coal combustion OA (CCOA) during HP, which was attributed to higher emissions at lower temperatures and coal combustion emissions, respectively. The relationship between light extinction and chemical composition was investigated using a multiple linear regression model. Our results showed that the largest contributors to particle extinction were ammonium nitrate (32%) and ammonium sulfate (28%) before and during HP, respectively. In addition, the contributions of SOA and primary OA to particle light extinction were quantified. The results showed that the OA extinction was mainly caused by SOA before HP and by SOA and CCOA during HP, yet with small contributions from HOA and cooking aerosol for the entire study period. Our results elucidate substantial changes of aerosol

  17. Evaluating Nighttime CALIOP 0.532 micron Aerosol Optical Depth and Extinction Coefficient Retrievals

    NASA Technical Reports Server (NTRS)

    Campbell, J. R.; Tackett, J. L.; Reid, J. S.; Zhang, J.; Curtis, C. A.; Hyer, E. J.; Sessions, W. R.; Westphal, D. L.; Prospero, J. M.; Welton, E. J.; hide

    2012-01-01

    NASA Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) Version 3.01 5-km nighttime 0.532 micron aerosol optical depth (AOD) datasets from 2007 are screened, averaged and evaluated at 1 deg X 1 deg resolution versus corresponding/co-incident 0.550 micron AOD derived using the US Navy Aerosol Analysis and Prediction System (NAAPS), featuring two-dimensional variational assimilation of quality-assured NASA Moderate Resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging Spectroradiometer (MISR) AOD. In the absence of sunlight, since passive radiometric AOD retrievals rely overwhelmingly on scattered radiances, the model represents one of the few practical global estimates available from which to attempt such a validation. Daytime comparisons, though, provide useful context. Regional-mean CALIOP vertical profiles of night/day 0.532 micron extinction coefficient are compared with 0.523/0.532 micron ground-based lidar measurements to investigate representativeness and diurnal variability. In this analysis, mean nighttime CALIOP AOD are mostly lower than daytime (0.121 vs. 0.126 for all aggregated data points, and 0.099 vs. 0.102 when averaged globally per normalised 1 deg. X 1 deg. bin), though the relationship is reversed over land and coastal regions when the data are averaged per normalised bin (0.134/0.108 vs. 0140/0.112, respectively). Offsets assessed within single bins alone approach +/- 20 %. CALIOP AOD, both day and night, are higher than NAAPS over land (0.137 vs. 0.124) and equal over water (0.082 vs. 0.083) when averaged globally per normalised bin. However, for all data points inclusive, NAAPS exceeds CALIOP over land, coast and ocean, both day and night. Again, differences assessed within single bins approach 50% in extreme cases. Correlation between CALIOP and NAAPS AOD is comparable during both day and night. Higher correlation is found nearest the equator, both as a function of sample size and relative signal magnitudes inherent at

  18. Characterizing the Vertical Distribution of Aerosols using Ground-based Multiwavelength Lidar Data

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Thorsen, T. J.; Clayton, M.; Mueller, D.; Chemyakin, E.; Burton, S. P.; Goldsmith, J.; Holz, R.; Kuehn, R.; Eloranta, E. W.; Marais, W.; Newsom, R. K.; Liu, X.; Sawamura, P.; Holben, B. N.; Hostetler, C. A.

    2016-12-01

    Observations of aerosol optical and microphysical properties are critical for developing and evaluating aerosol transport model parameterizations and assessing global aerosol-radiation impacts on climate. During the Combined HSRL And Raman lidar Measurement Study (CHARMS), we investigated the synergistic use of ground-based Raman lidar and High Spectral Resolution Lidar (HSRL) measurements to retrieve aerosol properties aloft. Continuous (24/7) operation of these co-located lidars during the ten-week CHARMS mission (mid-July through September 2015) allowed the acquisition of a unique, multiwavelength ground-based lidar dataset for studying aerosol properties above the Southern Great Plains (SGP) site. The ARM Raman lidar measured profiles of aerosol backscatter, extinction and depolarization at 355 nm as well as profiles of water vapor mixing ratio and temperature. The University of Wisconsin HSRL simultaneously measured profiles of aerosol backscatter, extinction and depolarization at 532 nm and aerosol backscatter at 1064 nm. Recent advances in both lidar retrieval theory and algorithm development demonstrate that vertically-resolved retrievals using such multiwavelength lidar measurements of aerosol backscatter and extinction can help constrain both the aerosol optical (e.g. complex refractive index, scattering, etc.) and microphysical properties (e.g. effective radius, concentrations) as well as provide qualitative aerosol classification. Based on this work, the NASA Langley Research Center (LaRC) HSRL group developed automated algorithms for classifying and retrieving aerosol optical and microphysical properties, demonstrated these retrievals using data from the unique NASA/LaRC airborne multiwavelength HSRL-2 system, and validated the results using coincident airborne in situ data. We apply these algorithms to the CHARMS multiwavelength (Raman+HSRL) lidar dataset to retrieve aerosol properties above the SGP site. We present some profiles of aerosol effective

  19. Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.; hide

    2000-01-01

    We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and Sun photometers during TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment). Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA/GSFC Scanning Raman Lidar (SRL) system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W), are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and rms differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a)=60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements.

  20. Demonstration of Aerosol Property Profiling by Multi-wavelength Lidar Under Varying Relative Humidity Conditions

    NASA Technical Reports Server (NTRS)

    Whiteman, D.N.; Veselovskii, I.; Kolgotin, A.; Korenskii, M.; Andrews, E.

    2008-01-01

    The feasibility of using a multi-wavelength Mie-Raman lidar based on a tripled Nd:YAG laser for profiling aerosol physical parameters in the planetary boundary layer (PBL) under varying conditions of relative humidity (RH) is studied. The lidar quantifies three aerosol backscattering and two extinction coefficients and from these optical data the particle parameters such as concentration, size and complex refractive index are retrieved through inversion with regularization. The column-integrated, lidar-derived parameters are compared with results from the AERONET sun photometer. The lidar and sun photometer agree well in the characterization of the fine mode parameters, however the lidar shows less sensitivity to coarse mode. The lidar results reveal a strong dependence of particle properties on RH. The height regions with enhanced RH are characterized by an increase of backscattering and extinction coefficient and a decrease in the Angstrom exponent coinciding with an increase in the particle size. We present data selection techniques useful for selecting cases that can support the calculation of hygroscopic growth parameters using lidar. Hygroscopic growth factors calculated using these techniques agree with expectations despite the lack of co-located radiosonde data. Despite this limitation, the results demonstrate the potential of multi-wavelength Raman lidar technique for study of aerosol humidification process.

  1. Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.

    2000-01-01

    We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and sun photometers during the Tropospheric Aerosol Radiative Forcing Observational Experiment. Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA Goddard Space Flight Center scanning Raman lidar system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W); are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and root-mean-square differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a) = 60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements. The lidar measurements of AOT are found to be generally within 25% of the AOT measured by the NASA Ames Airborne Tracking Sun Photometer (AATS-6). However, during certain periods the lidar and Sun photometer measurements of AOT differed significantly, possibly because of variations in the aerosol physical characteristics (e.g., size, composition) which affect S(sub a). Estimates of PWV, derived from water vapor mixing ratio profiles measured by LASE, are within 5-10% of PWV derived from the airborne Sun photometer. Aerosol extinction profiles measured by both lidars show that aerosols were generally concentrated in the lowest 2-3 km.

  2. Design Of A Novel Open-Path Aerosol Extinction Cavity Ringdown Spectrometer And Initial Data From Deployment At NOAA's Atmospheric Observatory

    NASA Astrophysics Data System (ADS)

    Gordon, T. D.; Wagner, N. L.; Richardson, M.; Law, D. C.; Wolfe, D. E.; Brock, C. A.; Erdesz, F.; Murphy, D. M.

    2014-12-01

    The ability to frame effective climate change policy depends strongly on reducing the uncertainty in aerosol radiative forcing, which is currently nearly as great as best estimates of its magnitude. Achieving this goal will require significant progress in measuring aerosol properties, including aerosol optical depth, single scattering albedo and the effect of relative humidity on these properties for both fine and coarse particles. However both ground- and space-based instruments fail or are highly biased in the presence of clouds, severely limiting quantitative estimates of the radiative effects of aerosols where they are advected over low-level clouds. Moreover, many in situ aerosol measurements exclude the coarse fraction, which can be very important in and downwind of desert regions. By measuring the decay rate of a pulsed laser in an optically resonant cavity, cavity ringdown spectrometers (CRDSs) have been employed successfully in measuring aerosol extinction for particles in relative humidities below 90%. At very high humidities (as found in and near clouds), however, existing CRDSs perform poorly, diverging significantly from theoretical extinction values as humidities approach 100%. The new open-path aerosol extinction CRDS described in this poster measures extinction as aerosol is drawn through the sample cavity directly without inlets or tubing for channeling the flow, which cause particle losses, condensation at high RH and other artifacts. This poster presents the key elements of the new open-path CRDS design as well as comparisons with an earlier generation closed-path CRDS and preliminary data obtained during a field study at the 300 meter tower at NOAA's Boulder Atmospheric Observatory (BAO) in Colorado.

  3. Raman Lidar Measurements of Aerosol Extinction and Backscattering. Report 2; Derivation of Aerosol Real Refractive Index, Single-Scattering Albedo, and Humidification Factor using Raman Lidar and Aircraft Size Distribution

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Poellot, M.; Kaufman, Y. J.

    1998-01-01

    Aerosol backscattering and extinction profiles measured by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site during two nights in April 1994 are discussed. These profiles are shown to be consistent with the simultaneous aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter flown on the University of North Dakota Citation aircraft. We describe a technique which uses both lidar and PCASP measurements to derive the dependence of particle size on relative humidity, the aerosol real refractive index n, and estimate the effective single-scattering albedo Omega(sub 0). Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); Omega(sub 0) varied between 0.7 and 1.0. The single-scattering albedo derived from this technique is sensitive to the manner in which absorbing particles are represented in the aerosol mixture; representing the absorbing particles as an internal mixture rather than the external mixture assumed here results in generally higher values of Omega(sub 0). The lidar measurements indicate that the change in particle size with relative humidity as measured by the PCASP can be represented in the form discussed by Hattel with the exponent gamma = 0.3 + or - 0.05. The variations in aerosol optical and physical characteristics captured in the lidar and aircraft size distribution measurements are discussed in the context of the meteorological conditions observed during the experiment.

  4. Raman lidar measurements of aerosol extinction and backscattering: 2. Derivation of aerosol real refractive index, single-scattering albedo, and humidification factor using Raman lidar and aircraft size distribution measurements

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.; Poellot, M.; Kaufman, Y. J.

    1998-08-01

    Aerosol backscattering and extinction profiles measured by the NASA Goddard Space Flight Center Scanning Raman Lidar (SRL) during the remote cloud sensing (RCS) intensive operations period (IOP) at the Department of Energy Atmospheric Radiation Measurement (ARM) southern Great Plains (SGP) site during two nights in April 1994 are discussed. These profiles are shown to be consistent with the simultaneous aerosol size distribution measurements made by a PCASP (Passive Cavity Aerosol Spectrometer Probe) optical particle counter flown on the University of North Dakota Citation aircraft. We describe a technique which uses both lidar and PCASP measurements to derive the dependence of particle size on relative humidity, the aerosol real refractive index n, and estimate the effective single-scattering albedo ω0. Values of n ranged between 1.4-1.5 (dry) and 1.37-1.47 (wet); ω0 varied between 0.7 and 1.0. The single-scattering albedo derived from this technique is sensitive to the manner in which absorbing particles are represented in the aerosol mixture; representing the absorbing particles as an internal mixture rather than the external mixture assumed here results in generally higher values of ω0. The lidar measurements indicate that the change in particle size with relative humidity as measured by the PCASP can be represented in the form discussed by Hanel [1976] with the exponent γ = 0.3 ± 0.05. The variations in aerosol optical and physical characteristics captured in the lidar and aircraft size distribution measurements are discussed in the context of the meteorological conditions observed during the experiment.

  5. Near Real Time Vertical Profiles of Clouds and Aerosols from the Cloud-Aerosol Transport System (CATS) on the International Space Station

    NASA Astrophysics Data System (ADS)

    Yorks, J. E.; McGill, M. J.; Nowottnick, E. P.

    2015-12-01

    Plumes from hazardous events, such as ash from volcanic eruptions and smoke from wildfires, can have a profound impact on the climate system, human health and the economy. Global aerosol transport models are very useful for tracking hazardous plumes and predicting the transport of these plumes. However aerosol vertical distributions and optical properties are a major weakness of global aerosol transport models, yet a key component of tracking and forecasting smoke and ash. The Cloud-Aerosol Transport System (CATS) is an elastic backscatter lidar designed to provide vertical profiles of clouds and aerosols while also demonstrating new in-space technologies for future Earth Science missions. CATS has been operating on the Japanese Experiment Module - Exposed Facility (JEM-EF) of the International Space Station (ISS) since early February 2015. The ISS orbit provides more comprehensive coverage of the tropics and mid-latitudes than sun-synchronous orbiting sensors, with nearly a three-day repeat cycle. The ISS orbit also provides CATS with excellent coverage over the primary aerosol transport tracks, mid-latitude storm tracks, and tropical convection. Data from CATS is used to derive properties of clouds and aerosols including: layer height, layer thickness, backscatter, optical depth, extinction, and depolarization-based discrimination of particle type. The measurements of atmospheric clouds and aerosols provided by the CATS payload have demonstrated several science benefits. CATS provides near-real-time observations of cloud and aerosol vertical distributions that can be used as inputs to global models. The infrastructure of the ISS allows CATS data to be captured, transmitted, and received at the CATS ground station within several minutes of data collection. The CATS backscatter and vertical feature mask are part of a customized near real time (NRT) product that the CATS processing team produces within 6 hours of collection. The continuous near real time CATS data

  6. Stratospheric Aerosol and Gas Experiment (SAGE) II and III Aerosol Extinction Measurements in the Arctic Middle and Upper Troposphere

    NASA Technical Reports Server (NTRS)

    Treffeisen, R. E.; Thomason, L. W.; Strom, J.; Herber, A. B.; Burton, S. P.; Yamanouchi, T.

    2006-01-01

    In recent years, substantial effort has been expended toward understanding the impact of tropospheric aerosols on Arctic climate and chemistry. A significant part of this effort has been the collection and documentation of extensive aerosol physical and optical property data sets. However, the data sets present significant interpretive challenges because of the diverse nature of these measurements. Among the longest continuous records is that by the spaceborne Stratospheric Aerosol and Gas Experiment (SAGE) II. Although SAGE tropospheric measurements are restricted to the middle and upper troposphere, they may be able to provide significant insight into the nature and variability of tropospheric aerosol, particularly when combined with ground and airborne observations. This paper demonstrates the capacity of aerosol products from SAGE II and its follow-on experiment SAGE III to describe the temporal and vertical variations of Arctic aerosol characteristics. We find that the measurements from both instruments are consistent enough to be combined. Using this combined data set, we detect a clear annual cycle in the aerosol extinction for the middle and upper Arctic troposphere.

  7. A study on characterization of stratospheric aerosol and gas parameters with the spacecraft solar occultation experiment

    NASA Technical Reports Server (NTRS)

    Chu, W. P.

    1977-01-01

    Spacecraft remote sensing of stratospheric aerosol and ozone vertical profiles using the solar occultation experiment has been analyzed. A computer algorithm has been developed in which a two step inversion of the simulated data can be performed. The radiometric data are first inverted into a vertical extinction profile using a linear inversion algorithm. Then the multiwavelength extinction profiles are solved with a nonlinear least square algorithm to produce aerosol and ozone vertical profiles. Examples of inversion results are shown illustrating the resolution and noise sensitivity of the inversion algorithms.

  8. Measurement of wavelength-dependent extinction to distinguish between absorbing and nonabsorbing aerosol particulates

    NASA Technical Reports Server (NTRS)

    Portscht, R.

    1977-01-01

    Measurements of spectral transmission factors in smoky optical transmission paths reveal a difference between wavelength exponents of the extinction cross section of high absorption capacity and those of low absorption capacity. A theoretical explanation of this behavior is presented. In certain cases, it is possible to obtain data on the absorption index of aerosol particles in the optical path by measuring the spectral decadic extinction coefficient at, at least, two wavelengths. In this manner it is possible, for instance, to distinguish smoke containing soot from water vapor.

  9. Airborne Lidar Measurements of Aerosol Optical Properties During SAFARI-2000

    NASA Technical Reports Server (NTRS)

    McGill, M. J.; Hlavka, D. L.; Hart, W. D.; Welton, E. J.; Campbell, J. R.; Starr, David OC. (Technical Monitor)

    2002-01-01

    The Cloud Physics Lidar (CPL) operated onboard the NASA ER-2 high altitude aircraft during the SAFARI-2000 field campaign. The CPL provided high spatial resolution measurements of aerosol optical properties at both 1064 nm and 532 nm. We present here results of planetary boundary layer (PBL) aerosol optical depth analysis and profiles of aerosol extinction. Variation of optical depth and extinction are examined as a function of regional location. The wide-scale aerosol mapping obtained by the CPL is a unique data set that will aid in future studies of aerosol transport. Comparisons between the airborne CPL and ground-based MicroPulse Lidar Network (MPL-Net) sites are shown to have good agreement.

  10. Aircraft Measurements of BrO, IO, Glyoxal, NO2, H2O, O2-O2 and Aerosol Extinction Profiles in the Tropics: Comparison with Aircraft-/Ship-Based in Situ and Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Volkamer, R.; Baidar, S.; Campos, T. L.; Coburn, S.; DiGangi, J. P.; Dix, B.; Eloranta, E. W.; Koenig, T. K.; Morley, B.; Ortega, I.; hide

    2015-01-01

    Tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO2), water vapor (H2O) and O2-O2 collision complexes (O4/ were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAXDOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosol spectrometer (UHSAS) and in situ H2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/ National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCDREF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship-based in situ cavity

  11. Validation of stratospheric aerosol and gas experiments 1 and 2 satellite aerosol optical depth measurements using surface radiometer data

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Mccormick, M. P.; Wang, P.-H.

    1994-01-01

    The stratospheric aerosol measurement 2, stratospheric aerosol and gas experiment (SAGE) 1, and SAGE 2 series of solar occultation satellite instruments were designed for the study of stratospheric aerosols and gases and have been extensively validated in the stratosphere. They are also capable, under cloud-free conditions, of measuring the extinction due to aerosols in the troposphere. Such tropospheric extinction measurements have yet to be validated by appropriate lidar and in situ techniques. In this paper published atmospheric aerosol optical depth measurements, made from high-altitude observatories during volcanically quiet periods, have been compared with optical depths calculated from local SAGE 1 and SAGE 2 extinction profiles. Surface measurements from three such observatories have been used, one located in Hawaii and two within the continental United States. Data have been intercompared on a seasonal basis at wave-lenths between 0.5 and 1.0 micron and found to agree within the range of measurement errors and expected atmospheric variation. The mean rms difference between the optical depths for corresponding satellite and surface measured data sets is 29%, and the mean ratio of the optical depths is 1.09.

  12. Research on the peculiarity of optical parameters of atmospheric aerosol in Guangzhou coastal areas

    NASA Astrophysics Data System (ADS)

    Li, Shasha; Li, Xuebin; Zhang, Wenzhong; Bai, Shiwei; Liu, Qing; Zhu, Wenyue; Weng, Ningquan

    2018-02-01

    The long-term measurement of atmospheric aerosol is constructed via such equipment as visibility meter, optical particle counter, solar radiometer, automatic weather station, aerosol laser radar and aerosol scattering absorption coefficient measurer and so on during the year of 2010 and 2017 in the coastal areas of Guangzhou, China to study the optical parameter characteristics of atmospheric aerosol and establish the aerosol optical parameter mode in such areas. The effects of temperature and humidity on aerosol concentration, extinction and absorption coefficient are analyzed and the statistical characteristics of atmospheric temperature and humidity, visibility, extinction profiles and other parameters in different months are tallied, preliminarily establishing the atmospheric aerosol optical parameter pattern in Guangzhou coastal areas.

  13. Evaluation of the aerosol vertical distribution in global aerosol models through comparison against CALIOP measurements: AeroCom phase II results: AEROSOL PROFILES IN AEROCOM II GCM

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koffi, Brigitte; Schulz, Michael; Bréon, François-Marie

    2016-06-27

    The ability of eleven models in simulating the aerosol vertical distribution from regional to global scales, as part of the second phase of the AeroCom model inter-comparison initiative (AeroCom II) is assessed and compared to results of the first phase. The evaluation is performed using a global monthly gridded dataset of aerosol extinction profiles built on purpose from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) Layer Product 3.01. Results over 12 sub-continental regions show that five models improved whereas three degraded in reproducing the Zα 0-6 km mean extinction height diagnostic, which is computed over the 0-6 km altitude rangemore » for each studied region and season. While the models’ performance remains highly variable, it has generally improved in terms of inter-regional diversity and seasonality. The biases in Zα 0-6 km have notably decreased in the U.S. and European industrial and downwind maritime regions, whereas the timing of the Zα 0-6 km peak season has improved for all but two models. However, most of the models now show a Zα 0-6 km underestimation over land, notably in the dust and biomass burning regions in Asia and Africa. At global scale, the AeroCom II models better reproduce the Zα 0-6 km latitudinal variability over ocean than over land. Hypotheses for the (changes in the) the performance of the individual models and for the inter-model diversity are discussed. We also provide an analysis of the CALIOP limitations and uncertainties that can contribute to the differences between the simulations and observations.« less

  14. Comparison of MADE3-simulated and observed aerosol distributions with a focus on aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Kaiser, Christopher; Hendricks, Johannes; Righi, Mattia; Jöckel, Patrick

    2016-04-01

    The reliability of aerosol radiative forcing estimates from climate models depends on the accuracy of simulated global aerosol distribution and composition, as well as on the models' representation of the aerosol-cloud and aerosol-radiation interactions. To help improve on previous modeling studies, we recently developed the new aerosol microphysics submodel MADE3 that explicitly tracks particle mixing state in the Aitken, accumulation, and coarse mode size ranges. We implemented MADE3 into the global atmospheric chemistry general circulation model EMAC and evaluated it by comparison of simulated aerosol properties to observations. Compared properties include continental near-surface aerosol component concentrations and size distributions, continental and marine aerosol vertical profiles, and nearly global aerosol optical depth. Recent studies have shown the specific importance of aerosol vertical profiles for determination of the aerosol radiative forcing. Therefore, our focus here is on the evaluation of simulated vertical profiles. The observational data is taken from campaigns between 1990 and 2011 over the Pacific Ocean, over North and South America, and over Europe. The datasets include black carbon and total aerosol mass mixing ratios, as well as aerosol particle number concentrations. Compared to other models, EMAC with MADE3 yields good agreement with the observations - despite a general high bias of the simulated mass mixing ratio profiles. However, BC concentrations are generally overestimated by many models in the upper troposphere. With MADE3 in EMAC, we find better agreement of the simulated BC profiles with HIPPO data than the multi-model average of the models that took part in the AeroCom project. There is an interesting difference between the profiles from individual campaigns and more "climatological" datasets. For instance, compared to spatially and temporally localized campaigns, the model simulates a more continuous decline in both total

  15. SAGE II observations of a previously unreported stratospheric volcanic aerosol cloud in the northern polar summer of 1990

    NASA Technical Reports Server (NTRS)

    Yue, Glenn K.; Veiga, Robert E.; Wang, Pi-Huan

    1994-01-01

    Analysis of aerosol extinction profiles obtained by the spaceborne SAGE II sensor reveals that there was an anomalous increase of aerosol extinction below 18.5 km at latitudes poleward of 50 deg N from July 28 to September 9, 1990. This widespread increase of aerosol extinction in the lower stratosphere was apparently due to a remote high-latitude volcanic eruption that has not been reported to date. The increase in stratospheric optical depth in the northern polar region was about 50% in August and had diminished by October 1990. This eruption caused an increase in stratospheric aerosol mass of about 0.33 x 10(exp 5) tons, assuming the aerosol was composed of sulfuric acid and water.

  16. SAM II aerosol profile measurements, Poker Flat, Alaska; July 16-19, 1979

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Chu, W. P.; Mcmaster, L. R.; Grams, G. W.; Herman, B. M.; Pepin, T. J.; Russell, P. B.; Swissler, T. J.

    1981-01-01

    SAM II satellite measurements during the July 1979 Poker Flat mission, yielded an aerosol extinction coefficient of 0.0004/km at 1.0 micron wavelength, in the region of the stratospheric aerosol mixing ratio peak (12-16 km). The stratospheric aerosol optical depth for these data, calculated from the tropopause through 30 km, is approximately 0.001. These results are consistent with the average 1979 summertime values found throughout the Arctic.

  17. Long-term Aerosol Lidar Measurements At CNR-IMAA

    NASA Astrophysics Data System (ADS)

    Mona, L.; Amodeo, A.; D'Amico, G.; Pandolfi, M.; Pappalardo, G.

    2006-12-01

    Actual estimations of the aerosol effect on the radiation budget are affected by a large uncertainties mainly due to the high inhomogeneity and variability of atmospheric aerosol, in terms of concentration, shape, size distribution, refractive index and vertical distribution. Long-term measurements of vertical profiles of aerosol optical properties are needed to reduce these uncertainties. At CNR-IMAA (40° 36'N, 15° 44' E, 760 m above sea level), a lidar system for aerosol study is operative since May 2000 in the framework of EARLINET (European Aerosol Research Lidar Network). Until August 2005, it provided independent measurements of aerosol extinction and backscatter at 355 nm and aerosol backscatter profiles at 532 nm. After an upgrade of the system, it provides independent measurements of aerosol extinction and backscatter profiles at 355 and 532 nm, and of aerosol backscatter profiles at 1064 nm and depolarization ratio at 532 nm. For these measurements, lidar ratio at 355 and 532 nm and Angstrom exponent profiles at 355/532 nm are also obtained. Starting on May 2000, systematic measurements are performed three times per week according to the EARLINET schedule and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. A climatological study has been carried out in terms of the seasonal behavior of the PBL height and of the aerosol optical properties calculated inside the PBL itself. In the free troposphere, an high occurrences of Saharan dust intrusions (about 1 day of Saharan dust intrusion every 10 days) has been observed at CNR-IMAA because of the short distance from the Sahara region. During 6 years of observations, very peculiar cases of volcanic aerosol emitted by Etna volcano and aerosol released by large forest fires burning occurred in Alaska and Canada have been observed in the free troposphere at our site. Particular attention is devoted to lidar ratio both for the

  18. Aerosol Optical Properties Measured Onboard the Ronald H. Brown During ACE Asia as a Function of Aerosol Chemical Composition and Source Region

    NASA Technical Reports Server (NTRS)

    Quinn, P. K.; Coffman, D. J.; Bates, T. S.; Welton, E. J.; Covert, D. S.; Miller, T. L.; Johnson, J. E.; Maria, S.; Russell, L.; Arimoto, R.

    2004-01-01

    During the ACE Asia intensive field campaign conducted in the spring of 2001 aerosol properties were measured onboard the R/V Ronald H. Brown to study the effects of the Asian aerosol on atmospheric chemistry and climate in downwind regions. Aerosol properties measured in the marine boundary layer included chemical composition; number size distribution; and light scattering, hemispheric backscattering, and absorption coefficients. In addition, optical depth and vertical profiles of aerosol 180 deg backscatter were measured. Aerosol within the ACE Asia study region was found to be a complex mixture resulting from marine, pollution, volcanic, and dust sources. Presented here as a function of air mass source region are the mass fractions of the dominant aerosol chemical components, the fraction of the scattering measured at the surface due to each component, mass scattering efficiencies of the individual components, aerosol scattering and absorption coefficients, single scattering albedo, Angstrom exponents, optical depth, and vertical profiles of aerosol extinction. All results except aerosol optical depth and the vertical profiles of aerosol extinction are reported at a relative humidity of 55 +/- 5%. An over-determined data set was collected so that measured and calculated aerosol properties could be compared, internal consistency in the data set could be assessed, and sources of uncertainty could be identified. By taking into account non-sphericity of the dust aerosol, calculated and measured aerosol mass and scattering coefficients agreed within overall experimental uncertainties. Differences between measured and calculated aerosol absorption coefficients were not within reasonable uncertainty limits, however, and may indicate the inability of Mie theory and the assumption of internally mixed homogeneous spheres to predict absorption by the ACE Asia aerosol. Mass scattering efficiencies of non-sea salt sulfate aerosol, sea salt, submicron particulate organic

  19. Aircraft measurements of BrO, IO, glyoxal, NO 2, H 2O, O 2–O 2 and aerosol extinction profiles in the tropics: comparison with aircraft-/ship-based in situ and lidar measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Volkamer, Rainer; Baidar, S.; Campos, T. L.

    Here, tropospheric chemistry of halogens and organic carbon over tropical oceans modifies ozone and atmospheric aerosols, yet atmospheric models remain largely untested for lack of vertically resolved measurements of bromine monoxide (BrO), iodine monoxide (IO) and small oxygenated hydrocarbons like glyoxal (CHOCHO) in the tropical troposphere. BrO, IO, glyoxal, nitrogen dioxide (NO 2), water vapor (H 2O) and O 2–O 2 collision complexes (O 4) were measured by the University of Colorado Airborne Multi-AXis Differential Optical Absorption Spectroscopy (CU AMAX-DOAS) instrument, aerosol extinction by high spectral resolution lidar (HSRL), in situ aerosol size distributions by an ultra high sensitivity aerosolmore » spectrometer (UHSAS) and in situ H 2O by vertical-cavity surface-emitting laser (VCSEL) hygrometer. Data are presented from two research flights (RF12, RF17) aboard the National Science Foundation/National Center for Atmospheric Research Gulfstream V aircraft over the tropical Eastern Pacific Ocean (tEPO) as part of the "Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated hydrocarbons" (TORERO) project (January/February 2012). We assess the accuracy of O 4 slant column density (SCD) measurements in the presence and absence of aerosols. Our O 4-inferred aerosol extinction profiles at 477 nm agree within 6% with HSRL in the boundary layer and closely resemble the renormalized profile shape of Mie calculations constrained by UHSAS at low (sub-Rayleigh) aerosol extinction in the free troposphere. CU AMAX-DOAS provides a flexible choice of geometry, which we exploit to minimize the SCD in the reference spectrum (SCD REF, maximize signal-to-noise ratio) and to test the robustness of BrO, IO and glyoxal differential SCDs. The RF12 case study was conducted in pristine marine and free tropospheric air. The RF17 case study was conducted above the NOAA RV Ka'imimoana (TORERO cruise, KA-12-01) and provides independent validation data from ship

  20. Optical and physical properties of stratospheric aerosols from balloon measurements in the visible and near-infrared domains. I. Analysis of aerosol extinction spectra from the AMON and SALOMON balloonborne spectrometers

    NASA Astrophysics Data System (ADS)

    Berthet, Gwenaël; Renard, Jean-Baptiste; Brogniez, Colette; Robert, Claude; Chartier, Michel; Pirre, Michel

    2002-12-01

    Aerosol extinction coefficients have been derived in the 375-700-nm spectral domain from measurements in the stratosphere since 1992, at night, at mid- and high latitudes from 15 to 40 km, by two balloonborne spectrometers, Absorption par les Minoritaires Ozone et NOx (AMON) and Spectroscopie d'Absorption Lunaire pour l'Observation des Minoritaires Ozone et NOx (SALOMON). Log-normal size distributions associated with the Mie-computed extinction spectra that best fit the measurements permit calculation of integrated properties of the distributions. Although measured extinction spectra that correspond to background aerosols can be reproduced by the Mie scattering model by use of monomodal log-normal size distributions, each flight reveals some large discrepancies between measurement and theory at several altitudes. The agreement between measured and Mie-calculated extinction spectra is significantly improved by use of bimodal log-normal distributions. Nevertheless, neither monomodal nor bimodal distributions permit correct reproduction of some of the measured extinction shapes, especially for the 26 February 1997 AMON flight, which exhibited spectral behavior attributed to particles from a polar stratospheric cloud event.

  1. Aerosol Correction for Improving OMPS/LP Ozone Retrieval

    NASA Technical Reports Server (NTRS)

    Chen, Zhong; Bhartia, Pawan K.; Loughman, Robert

    2015-01-01

    The Ozone Mapping and Profiler Suite Limb Profiler (OMPS-LP) on board the Suomi National Polar-orbiting Partnership (SNPP) satellite was launched on Oct. 28, 2011. Limb profilers measures the radiance scattered from the Earth's atmospheric in limb viewing mode from 290 to 1000 nm and infer ozone profiles from tropopause to 60 km. The recently released OMPS-LP Version 2 data product contains the first publicly released ozone profiles retrievals, and these are now available for the entire OMPS mission, which extends from April, 2012. The Version 2 data product retrievals incorporate several important improvements to the algorithm. One of the primary changes is to turn off the aerosol retrieval module. The aerosol profiles retrieved inside the ozone code was not helping the ozone retrieval and was adding noise and other artifacts. Aerosols including polar stratospheric cloud (PSC) and polar mesospheric clouds (PMC) have a detectable effect on OMPS-LP data. Our results show that ignoring the aerosol contribution would produce an ozone density bias of up to 10 percent in the region of maximum aerosol extinction. Therefore, aerosol correction is needed to improve the quality of the retrieved ozone concentration profile. We provide Aerosol Scattering Index (ASI) for detecting aerosols-PMC-PSC, defined as ln(Im-Ic) normalized at 45km, where Im is the measured radiance and Ic is the calculated radiance assuming no aerosols. Since ASI varies with wavelengths, latitude and altitude, we can start by assuming no aerosol profiles in calculating the ASIs and then use the aerosol profile to see if it significantly reduces the residuals. We also discuss the effect of aerosol size distribution on the ozone profile retrieval process. Finally, we present an aerosol-PMC-PSC correction scheme.

  2. Impact of radon gas concentration in the aerosoles profile

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lukaj, Edmond, E-mail: mondilukaj@yahoo.com; Vila, Floran, E-mail: floranvila@yahoo.com; Mandija, Florian, E-mail: fmandija@yahoo.com

    Radon gases relased from building materials and from earth surface are the major responsibility of air ionization. Radon nuclear decay can produce an alpha particle with high energy and Radon progeny. This particle and gamma rays can deliver particles in the air and produce ions with different polarities. This ions, because of induced electric charge, can attach with air aerosols and charge them with their electric charge. The charged aerosols can interact with the other aerosols and ions. Because of this exchange, the air conductivity and the aerosol profiles will change dependently by Radon gas concentration and gamma radiation. Observationsmore » show an increase in concentration of Radon during the night, and a decrease during the daylight time. The Radon gas concentration changed hour by hour can induce aerosol profile to change. This dependency between the aerosol profiles and the Radon gas concentrations is discussed.« less

  3. Three-dimensional dust aerosol distribution and extinction climatology over northern Africa simulated with the ALADIN numerical prediction model from 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Tulet, P.; Fischer, C.; Bouteloup, Y.; Bouyssel, F.; Brachemi, O.

    2015-08-01

    The seasonal cycle and optical properties of mineral dust aerosols in northern Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled to the surface scheme SURFEX (SURFace EXternalisée). The particularity of the simulations is that the major physical processes responsible for dust emission and transport, as well as radiative effects, are taken into account on short timescales and at mesoscale resolution. The aim of these simulations is to quantify the dust emission and deposition, locate the major areas of dust emission and establish a climatology of aerosol optical properties in northern Africa. The mean monthly aerosol optical thickness (AOT) simulated by ALADIN is compared with the AOTs derived from the standard Dark Target (DT) and Deep Blue (DB) algorithms of the Aqua-MODIS (MODerate resolution Imaging Spectroradiometer) products over northern Africa and with a set of sun photometer measurements located at Banizoumbou, Cinzana, Soroa, Mbour and Cape Verde. The vertical distribution of dust aerosol represented by extinction profiles is also analysed using CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. The annual dust emission simulated by ALADIN over northern Africa is 878 Tg year-1. The Bodélé Depression appears to be the main area of dust emission in northern Africa, with an average estimate of about 21.6 Tg year-1. The simulated AOTs are in good agreement with satellite and sun photometer observations. The positions of the maxima of the modelled AOTs over northern Africa match the observed positions, and the ALADIN simulations satisfactorily reproduce the various dust events over the 2006-2010 period. The AOT climatology proposed in this paper provides a solid database of optical properties and consolidates the existing climatology over this region derived from satellites, the AERONET network and regional climate

  4. Evaluating Satellite Retrievals of Smoke Aerosol above Clouds using Airborne High Spectral Resolution Lidar Measurements during ORACLES

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Burton, S. P.; Cook, A. L.; Harper, D. B.; Hostetler, C. A.; Hair, J. W.; Vaughan, M.; Hu, Y.; Fenn, M. A.; Clayton, M.; Scarino, A. J.; Jethva, H. T.; Sayer, A. M.; Meyer, K.; Torres, O.; Josset, D. B.; Redemann, J.

    2017-12-01

    The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL-2) provided extensive measurements of smoke above shallow marine clouds while deployed from the NASA ER-2 aircraft during the NASA EV-S Observations of Aerosols above Clouds and their Interactions (ORACLES) mission. During the first ORACLES field campaign in September 2016, the ER-2 was deployed from Walvis Bay, Namibia and conducted flights over the southeastern Atlantic Ocean. HSRL-2 measured profiles of aerosol backscattering, extinction and aerosol optical depth (AOD) at 355 and 532 nm and aerosol backscattering and depolarization at 1064 nm and so provided an excellent characterization of the widespread smoke layers above shallow marine clouds. OMI, MODIS, and CALIOP satellite retrievals of above cloud AOD (ACAOD) are compared to the HSRL-2 measurements. The OMI above-cloud aerosols data product (OMACA) ACAOD product relies on the spectral contrast produced by aerosol absorption in two near-UV measurements (354 and 388 nm) to derive ACAOD. Two MODIS ACAOD products are examined; the first ("multichannel') relies on the spectral contrast in aerosol absorption derived from reflectance measurements at six MODIS channels from the visible to the shortwave infrared (swIR). The second method is an extension of the "Deep Blue" method and differs from the multichannel method in that it does not use swIR channels. The CALIOP V4 operational and "depolarization ratio (DR)" methods of retrieving ACAOD are also examined. The MODIS and OMI ACAOD values were well correlated (r2>0.6) with the HSRL-2 ACAOD values; bias differences were generally less than about 0.1 at 532 nm (10-30%). The CALIOP operational retrievals missed a significant amount of aerosol and so were biased low by 50-75% compared to HSRL-2. In contrast, the CALIOP DR method produced ACAOD values in excellent agreement (bias differences less than 0.03 (5%)) with HSRL-2. Aerosol extinction profiles computed for the smoke layer using

  5. On-site ocean horizontal aerosol extinction coefficient inversion under different weather conditions on the Bo-hai and Huang-hai Seas

    NASA Astrophysics Data System (ADS)

    Zeng, Xianjiang; Xia, Min; Ge, Yinghui; Guo, Wenping; Yang, Kecheng

    2018-03-01

    In this paper, we explore the horizontal extinction characteristics under different weather conditions on the ocean surface with on-site experiments on the Bo-hai and Huang-hai Seas in the summer of 2016. An experimental lidar system is designed to collect the on-site experimental data. By aiming at the inhomogeneity and uncertainty of the horizontal aerosol in practice, a joint retrieval method is proposed to retrieve the aerosol extinction coefficients (AEC) from the raw data along the optical path. The retrieval results of both the simulated and the real signals demonstrate that the joint retrieval method is practical. Finally, the sequence observation results of the on-site experiments under different weather conditions are reported and analyzed. These results can provide the attenuation information to analyze the atmospheric aerosol characteristics on the ocean surface.

  6. A Comparison of Aerosol Optical Property Measurements Made During the DOE Aerosol Intensive Operating Period and Their Effects on Regional Climate

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Hallar, A. G.; Arnott, W. P.; Covert, D.; Elleman, R.; Ogren, J.; Schmid, B.; Luu, A.

    2004-01-01

    The amount of radiant energy an aerosol absorbs has profound effects on climate and air quality. It is ironic that aerosol absorption coefficient is one of the most difficult to measure aerosol properties. One of the main purposes of the DOE Aerosol Intensive Operating Period (IOP) flown in May, 2003 was to assess our ability to measure absorption coefficient in situ. This paper compares measurements of aerosol optical properties made during the IOP. Measurements of aerosol absorption coefficient were made by Particle Soot Absorption Photometer (PSAP) aboard the CIRPAS Twin-Otter (U. Washington) and on the DOE Cessna 172 (NOAA-C,MDL). Aerosol absorption coefficient was also measured by a photoacoustic instrument (DRI) that was operated on an aircraft for the first time during the IOP. A new cavity ring-down (CRD) instrument, called Cadenza (NASA-AkC), measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. Absorption coefficient is obtained from the difference of measured extinction and scattering within the instrument. Measurements of absorption coefficient from all of these instruments during appropriate periods are compared. During the IOP, several significant aerosol layers were sampled aloft. These layers are identified in the remote (AATS-14) as well as in situ measurements. Extinction profiles measured by Cadenza are compared to those derived from the Ames Airborne Tracking Sunphotometer (AATS-14, NASA-ARC). The regional radiative impact of these layers is assessed by using the measured aerosol optical properties in a radiative transfer model.

  7. Measurement of phase function of aerosol at different altitudes by CCD Lidar

    NASA Astrophysics Data System (ADS)

    Sun, Peiyu; Yuan, Ke'e.; Yang, Jie; Hu, Shunxing

    2018-02-01

    The aerosols near the ground are closely related to human health and climate change, the study on which has important significance. As we all know, the aerosol is inhomogeneous at different altitudes, of which the phase function is also different. In order to simplify the retrieval algorithm, it is usually assumed that the aerosol is uniform at different altitudes, which will bring measurement error. In this work, an experimental approach is demonstrated to measure the scattering phase function of atmospheric aerosol particles at different heights by CCD lidar system, which could solve the problem of the traditional CCD lidar system in assumption of phase function. The phase functions obtained by the new experimental approach are used to retrieve the aerosol extinction coefficient profiles. By comparison of the aerosol extinction coefficient retrieved by Mie-scattering aerosol lidar and CCD lidar at night, the reliability of new experimental approach is verified.

  8. Characterization of Florida red tide aerosol and the temporal profile of aerosol concentration.

    PubMed

    Cheng, Yung Sung; Zhou, Yue; Pierce, Richard H; Henry, Mike; Baden, Daniel G

    2010-05-01

    Red tide aerosols containing aerosolized brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide aerosols in human volunteer studies, in which an asthma cohort spent 1h on Siesta Beach (Sarasota, Florida) during aerosolized red tide events and non-exposure periods. Aerosol concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the aerosol mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the aerosol. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5-10 microg/L, and the corresponding brevetoxin level of Florida red tide aerosol ranged between 21 and 39 ng/m(3). The temporal profiles of red tide aerosol concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide aerosol. By continuously monitoring the marine aerosol and wind direction at Siesta Beach, we observed that the marine aerosol concentration varied as the wind direction changed. The temporal profile of the Florida red tide aerosol during a sampling period could be explained generally with the variation of wind direction. Copyright 2009 Elsevier Ltd. All rights reserved.

  9. SAGE III Aerosol Extinction Validation in the Arctic Winter: Comparisons with SAGE II and POAM III

    NASA Technical Reports Server (NTRS)

    Thomason, L. W.; Poole, L. R.; Randall, C. E.

    2007-01-01

    The use of SAGE III multiwavelength aerosol extinction coefficient measurements to infer PSC type is contingent on the robustness of both the extinction magnitude and its spectral variation. Past validation with SAGE II and other similar measurements has shown that the SAGE III extinction coefficient measurements are reliable though the comparisons have been greatly weighted toward measurements made at mid-latitudes. Some aerosol comparisons made in the Arctic winter as a part of SOLVE II suggested that SAGE III values, particularly at longer wavelengths, are too small with the implication that both the magnitude and the wavelength dependence are not reliable. Comparisons with POAM III have also suggested a similar discrepancy. Herein, we use SAGE II data as a common standard for comparison of SAGE III and POAM III measurements in the Arctic winters of 2002/2003 through 2004/2005. During the winter, SAGE II measurements are made infrequently at the same latitudes as these instruments. We have mitigated this problem through the use potential vorticity as a spatial coordinate and thus greatly increased the number of coincident events. We find that SAGE II and III extinction coefficient measurements show a high degree of compatibility at both 1020 nm and 450 nm except a 10-20% bias at both wavelengths. In addition, the 452 to 1020-nm extinction ratio shows a consistent bias of approx. 30% throughout the lower stratosphere. We also find that SAGE II and POAM III are on average consistent though the comparisons show a much higher variability and larger bias than SAGE II/III comparisons. In addition, we find that the two data sets are not well correlated below 18 km. Overall, we find both the extinction values and the spectral dependence from SAGE III are robust and we find no evidence of a significant defect within the Arctic vortex.

  10. Aerosol composition and variability in the Baltimore-Washington, DC region

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Chen, G.; Corr, C. A.; Crawford, J. H.; Diskin, G. S.; Moore, R. H.; Thornhill, K. L.; Winstead, E. L.; Anderson, B. E.

    2015-08-01

    In order to utilize satellite-based aerosol measurements for the determination of air quality, the relationship between aerosol optical properties (wavelength-dependent, column-integrated extinction measured by satellites) and mass measurements of aerosol loading (PM2.5 used for air quality monitoring) must be understood. This connection varies with many factors including those specific to the aerosol type, such as composition, size and hygroscopicity, and to the surrounding atmosphere, such as temperature, relative humidity (RH) and altitude, all of which can vary spatially and temporally. During the DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project, extensive in-situ atmospheric profiling in the Baltimore, MD-Washington, DC region was performed during fourteen flights in July 2011. Identical flight plans and profile locations throughout the project provide meaningful statistics for determining the variability in and correlations between aerosol loading, composition, optical properties and meteorological conditions. Measured water-soluble aerosol mass was composed primarily of ammonium sulfate (campaign average of 32 %) and organics (57 %). A distinct difference in composition was observed with high-loading days having a proportionally larger percentage of ammonium sulfate (up to 49 %) due to transport from the Ohio River Valley. This composition shift caused a change in the aerosol water-uptake potential (hygroscopicity) such that higher relative contributions of ammonium sulfate increased the bulk aerosol hygroscopicity. These days also tended to have higher relative humidity causing an increase in the water content of the aerosol. Conversely, low aerosol loading days had lower ammonium sulfate and higher black carbon contributions causing lower single scattering albedos (SSAs). The average black carbon concentrations were 240 ng m-3 in the lowest 1 km decreasing to 35 ng m-3

  11. Evaluation of Daytime Measurements of Aerosols and Water Vapor made by an Operational Raman Lidar over the Southern Great Plains

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard; Turner, David; Clayton, Marian; Schmid, Beat; Covert, David; Elleman, Robert; Orgren, John; Andrews, Elisabeth; Goldsmith, John E. M.; Jonsson, Hafidi

    2006-01-01

    Raman lidar water vapor and aerosol extinction profiles acquired during the daytime over the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site in northern Oklahoma (36.606 N, 97.50 W, 315 m) are evaluated using profiles measured by in situ and remote sensing instruments deployed during the May 2003 Aerosol Intensive Operations Period (IOP). The automated algorithms used to derive these profiles from the Raman lidar data were first modified to reduce the adverse effects associated with a general loss of sensitivity of the Raman lidar since early 2002. The Raman lidar water vapor measurements, which are calibrated to match precipitable water vapor (PWV) derived from coincident microwave radiometer (MWR) measurements were, on average, 5-10% (0.3-0.6 g/m(exp 3) higher than the other measurements. Some of this difference is due to out-of-date line parameters that were subsequently updated in the MWR PWV retrievals. The Raman lidar aerosol extinction measurements were, on average, about 0.03 km(exp -1) higher than aerosol measurements derived from airborne Sun photometer measurements of aerosol optical thickness and in situ measurements of aerosol scattering and absorption. This bias, which was about 50% of the mean aerosol extinction measured during this IOP, decreased to about 10% when aerosol extinction comparisons were restricted to aerosol extinction values larger than 0.15 km(exp -1). The lidar measurements of the aerosol extinction/backscatter ratio and airborne Sun photometer measurements of the aerosol optical thickness were used along with in situ measurements of the aerosol size distribution to retrieve estimates of the aerosol single scattering albedo (omega(sub o)) and the effective complex refractive index. Retrieved values of omega(sub o) ranged from (0.91-0.98) and were in generally good agreement with omega(sub o) derived from airborne in situ measurements of scattering and absorption. Elevated aerosol

  12. ACE-Asia Aerosol Optical Depth and Water Vapor Measured by Airborne Sunphotometers and Related to Other Measurements and Calculations

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Russell, P. B.; Schmid, B.; Redemann, J.; Eilers, J. A.; Ramirez, S. A.; Kahn, R.; Hegg, D.; Pilewskie, P.; Anderson, T.; hide

    2001-01-01

    In the Spring 2001 phase of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), the 6-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) operated on 15 of the 19 research flights of the NCAR C-130, while its 14-channel counterpart (AATS- 14) flew successfully on all 18 research flights of the CIRPAS Twin Otter. ACE-Asia studied aerosol outflow from the Asian continent to the Pacific basin. It was designed to integrate suborbital and satellite measurements and models so as to reduce the uncertainty in calculations of the climate forcing due to aerosols. AATS-6 and AATS-14 measured solar beam transmission at 6 and 14 wavelengths (380-1021 and 354-1558 nm, respectively), yielding aerosol optical depth (AOD) spectra and column water vapor (CWV). Vertical differentiation in profiles yielded aerosol extinction spectra and water vapor concentration. The wavelength dependence of these AOD and extinction spectra indicates that supermicron dust was often a major component of the ACE-Asia aerosol. Frequently this dust-containing aerosol extended to high altitudes. For example, in AATS- 14 profiles analyzed to date, 36% of full-column AOD at 525 nm was above 3 km. In contrast, only 10% of CWV was above 3 km. Analyses and applications of AATS-6 and AATS-14 data to date include comparisons to (i) extinction products derived using in situ measurements, (ii) extinction profiles derived from lidar measurements, and (iii) AOD retrievals from the Multi-angle Imaging Spectro-Radiometer (MISR) aboard the TERRA satellite. Other planned collaborative studies include comparisons to results from size spectrometers, chemical measurements, other satellite sensors, flux radiometers, and chemical transport models. Early results of these studies will be presented.

  13. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard A.; Browell, Edward V.; Kooi, Susan A.; Dunion, Jason P.; Heymsfield, Gerry; Notari, Anthony; Butler, Carolyn F.; Burton, Sharon; Fenn, Marta; hide

    2010-01-01

    LASE (Lidar Atmospheric Sensing Experiment) on-board the NASA DC-8 measured high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan Air Layer(s) (SAL). Interactions between the SAL and tropical air were observed during the early stages of the TC development. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on AEWs and TCs. Examples of profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in SAL, convection, and clear air regions. LASE data suggest that the SAL suppresses low-altitude convection at the convection-SAL interface region. Mid-level convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on August 20, 2008. This interaction is responsible for the transfer of about 7 x 10(exp 15) J latent heat energy within a day to the SAL. Measurements of lidar extinction-to-backscatter ratios in the range 36+/-5 to 45+/-5 are within the range of measurements from other lidar measurements of dust. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively.

  14. Phase function, backscatter, extinction, and absorption for standard radiation atmosphere and El Chichon aerosol models at visible and near-infrared wavelengths

    NASA Technical Reports Server (NTRS)

    Whitlock, C. H.; Suttles, J. T.; Lecroy, S. R.

    1985-01-01

    Tabular values of phase function, Legendre polynominal coefficients, 180 deg backscatter, and extinction cross section are given for eight wavelengths in the atmospheric windows between 0.4 and 2.2 microns. Also included are single scattering albedo, asymmetry factor, and refractive indices. These values are based on Mie theory calculations for the standard rediation atmospheres (continental, maritime, urban, unperturbed stratospheric, volcanic, upper atmospheric, soot, oceanic, dust, and water-soluble) assest measured volcanic aerosols at several time intervals following the El Chichon eruption. Comparisons of extinction to 180 deg backscatter for different aerosol models are presented and related to lidar data.

  15. Measurement of tropospheric aerosol in São Paulo area using a new upgraded Raman LIDAR system

    NASA Astrophysics Data System (ADS)

    Landulfo, Eduardo; Rodrigues, Patrícia F.; da Silva Lopes, Fábio Juliano; Bourayou, Riad

    2012-11-01

    Elastic backscatter LIDAR systems have been used to determine aerosol profile concentration in several areas such as weather, pollution and air quality monitoring. In order to determine the aerosol extinction and backscattering profiles, the Klett inversion method is largely used, but this method suffers from lack of information since there are two unknown variables to be determined using only one measured LIDAR signal, and assumption of the LIDAR ratio (the relation between the extinction and backscattering coefficients) is needed. When a Raman LIDAR system is used, the inelastic backscattering signal is affected by aerosol extinction but not by aerosol backscatter, which allows this LIDAR to uniquely determine extinction and backscattering coefficients without any assumptions or any collocated instruments. The MSP-LIDAR system, set-up in a highly dense suburban area in the city of São Paulo, has been upgraded to a Raman LIDAR, and in its actual 6-channel configuration allows it to monitor elastic backscatter at 355 and 532 nm together with nitrogen and water vapor Raman backscatters at 387nm and 608 nm and 408nm and 660 nm, respectively. Thus, the measurements of aerosol backscattering, extinction coefficients and water vapor mixing ratio in the Planetary Boundary Layer (PBL) are becoming available. The system will provide the important meteorological parameters such as Aerosol Optical Depth (AOD) and will be used for the study of aerosol variations in lower troposphere over the city of São Paulo, air quality monitoring and for estimation of humidity impact on the aerosol optical properties, without any a priori assumption. This study will present the first results obtained with this upgraded LIDAR system, demonstrating the high quality of obtained aerosol and water vapor data. For that purpose, we compared the data obtained with the new MSP-Raman LIDAR with a mobile Raman LIDAR collocated at the Center for Lasers and Applications, Nuclear and Energy Research

  16. On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

    DOE PAGES

    Kovilakam, Mahesh; Deshler, Terry

    2015-08-26

    In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997-2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPCmore » measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15-30% (30-50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. Furthermore, this disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the ± 40% precision of the OPC moment calculations.« less

  17. On the accuracy of stratospheric aerosol extinction derived from in situ size distribution measurements and surface area density derived from remote SAGE II and HALOE extinction measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kovilakam, Mahesh; Deshler, Terry

    In situ stratospheric aerosol measurements, from University of Wyoming optical particle counters (OPCs), are compared with Stratospheric Aerosol Gas Experiment (SAGE) II (versions 6.2 and 7.0) and Halogen Occultation Experiment (HALOE) satellite measurements to investigate differences between SAGE II/HALOE-measured extinction and derived surface area and OPC-derived extinction and surface area. Coincident OPC and SAGE II measurements are compared for a volcanic (1991-1996) and nonvolcanic (1997-2005) period. OPC calculated extinctions agree with SAGE II measurements, within instrumental uncertainty, during the volcanic period, but have been a factor of 2 low during the nonvolcanic period. Three systematic errors associated with the OPCmore » measurements, anisokineticity, inlet particle evaporation, and counting efficiency, were investigated. An overestimation of the OPC counting efficiency is found to be the major source of systematic error. With this correction OPC calculated extinction increases by 15-30% (30-50%) for the volcanic (nonvolcanic) measurements. These changes significantly improve the comparison with SAGE II and HALOE extinctions in the nonvolcanic cases but slightly degrade the agreement in the volcanic period. These corrections have impacts on OPC-derived surface area density, exacerbating the poor agreement between OPC and SAGE II (version 6.2) surface areas. Furthermore, this disparity is reconciled with SAGE II version 7.0 surface areas. For both the volcanic and nonvolcanic cases these changes in OPC counting efficiency and in the operational SAGE II surface area algorithm leave the derived surface areas from both platforms in significantly better agreement and within the ± 40% precision of the OPC moment calculations.« less

  18. SAM 2 measurements of the polar stratospheric aerosol. Volume 9: October 1982 - April 1983

    NASA Technical Reports Server (NTRS)

    Mcmaster, L. R.; Powell, K. A.

    1991-01-01

    The Stratospheric Aerosol Measurement (SAM) II sensor aboard Nimbus 7 is providing 1.0 micron extinction measurements of Antarctic and Arctic stratospheric aerosols with a vertical resolution of 1 km. Representative examples and weekly averages including corresponding temperature profiles provided by NOAA for the time and place of each SAM II measurement are presented. Contours of aerosol extinction as a function of altitude and longitude or time are plotted, and aerosol optical depths are calculated for each week. Typical values of aerosol extinction and stratospheric optical depth in the Arctic are unusually large due to the presence of material from the El Chichon volcano eruption in the Spring of 1982. For example, the optical depth peaked at 0.068, more than 50 times background values. Typical values of aerosol extinction and stratospheric optical depth in the Antarctic varied considerably during this period due to the transport and arrival of the material from the El Chichon eruption. For example, the stratospheric optical depth varied from 0.002 in October 1982, to 0.021 in January 1983. Polar stratospheric clouds were observed during the Arctic winter, as expected. A representative sample is provided of the ninth 6-month period of data to be used in atmospheric and climatic studies.

  19. Airborne Sunphotometry of Aerosol Optical Depth and Columnar Water Vapor During ACE-Asia

    NASA Technical Reports Server (NTRS)

    Redemann, Jens; Schmid, B.; Russell, P. B.; Livingston, J. M.; Eilers, J. A.; Ramirez, S. A.; Kahn, R.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    During the Intensive Field Campaign (IFC) of the Aerosol Characterization Experiment - Asia (ACE-Asia), March-May 2001, the 6-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) operated during 15 of the 19 research flights aboard the NCAR C- 130, while its 14-channel counterpart (AATS- 14) was flown successfully on all 18 research flights of a Twin Otter aircraft operated by the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS), Monterey, CA. ACE-Asia was the fourth in a series of aerosol characterization experiments and focused on aerosol outflow from the Asian continent to the Pacific basin. Each ACE was designed to integrate suborbital and satellite measurements and models so as to reduce the uncertainty in calculations of the climate forcing due to aerosols. The Ames Airborne Tracking Sunphotometers measured solar beam transmission at 6 (380-1021 nm, AATS-6) and 14 wavelengths (353-1558 nm, AATS-14) respectively, yielding aerosol optical depth (AOD) spectra and column water vapor (CWV). Vertical differentiation in profiles yielded aerosol extinction and water vapor concentration. The wavelength dependence of AOD and extinction indicates that supermicron dust was often a major component of the aerosol. Frequently this dust-containing aerosol extended to high altitudes. For example, in data flights analyzed to date 34 +/- 13% of full-column AOD(525 nm) was above 3 km. In contrast, only 10 +/- 4% of CWV was above 3 km. In this paper, we will show first sunphotometer-derived results regarding the spatial variation of AOD and CWV, as well as the vertical distribution of aerosol extinction and water vapor concentration. Preliminary comparison studies between our AOD/aerosol extinction data and results from: (1) extinction products derived using in situ measurements and (2) AOD retrievals using the Multi-angle Imaging Spectro-Radiometer (MISR) aboard the TERRA satellite will also be presented.

  20. Lidar Observations of Tropospheric Aerosols Over Northeastern South Africa During the ARREX and SAFARI-2000 Dry Season Experiments

    NASA Technical Reports Server (NTRS)

    Campbell, James R.; Welton, Ellsworth J.; Spinhirne, James D.; Ji, Qiang; Tsay, Si-Chee; Piketh, Stuart J.; Barenbrug, Marguerite; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    During the ARREX-1999 and SAFARI-2000 Dry Season experiments a micropulse lidar (523 nm) instrument was operated at the Skukuza Airport in northeastern South Africa. The Mar was collocated with a diverse array of passive radiometric equipment. For SAFARI-2000 the processed Mar data yields a daytime time-series of layer mean/derived aerosol optical properties, including extinction-to-backscatter ratios and vertical extinction cross-section profile. Combined with 523 run aerosol optical depth and spectral Angstrom exponent calculations from available CIMEL sun-photometer data and normalized broadband flux measurements the temporal evolution of the near surface aerosol layer optical properties is analyzed for climatological trends. For the densest smoke/haze events the extinction-to-backscatter ratio is found to be between 60-80/sr, and corresponding Angstrom exponent calculations near and above 1.75. The optical characteristics of an evolving smoke event from SAFARI-2000 are extensively detailed. The advecting smoke was embedded within two distinct stratified thermodynamic layers, causing the particulate mass to advect over the instrument array in an incoherent manner on the afternoon of its occurrence. Surface broadband flux forcing due to the smoke is calculated, as is the evolution in the vertical aerosol extinction profile as measured by the Han Finally, observations of persistent elevated aerosol during ARREX-1999 are presented and discussed. The lack of corroborating observations the following year makes these observation; both unique and noteworthy in the scope of regional aerosol transport over southern Africa.

  1. Field test of a new instrument to measure UV/Vis (300-700 nm) ambient aerosol extinction spectra in Colorado during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Anderson, B. E.; Beyersdorf, A. J.; Dibb, J. E.; Greenslade, M. E.; Martin, R.; Scheuer, E. M.; Shook, M.; Thornhill, K. L., II; Troop, D.; Winstead, E.; Ziemba, L. D.

    2014-12-01

    An optical instrument has been developed to investigate aerosol extinction spectra in the ambient atmosphere. Based on a White-type cell design and using a differential optical approach, aerosol extinction spectra over the 300-700 nm ultraviolet and visible (UV/Vis) wavelength range are obtained. Laboratory tests conducted at NASA Langley Research Center (NASA LaRC) in March 2014 showed good agreement with Cavity Attenuated Phase Shift (CAPS PMex, Aerodyne Research) extinction measurements (at 450, 530, and 630 nm) for a variety of aerosols, e.g., scatterers such as polystyrene latex spheres and ammonium sulfate; absorbers such as dust (including pigmented minerals), smoke (generated in a miniCAST burning propane) and laboratory smoke analogs (e.g., fullerene soot and aquadag). The instrument was field tested in Colorado in July and August 2014 aboard the NASA mobile laboratory at various ground sites during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) field campaign. A description of the instrument, results from the laboratory tests, and summer field data will be presented. The instrument provides a new tool for probing in situ aerosol optical properties that may help inform remote sensing approaches well into the UV range.

  2. Application of the CALIOP Layer Product to Evaluate the Vertical Distribution of Aerosols Estimated by Global Models: AeroCom Phase I Results

    NASA Technical Reports Server (NTRS)

    Koffi, Brigitte; Schulz, Michael; Breon, Francois-Marie; Griesfeller, Jan; Winker, David; Balkanski, Yves; Bauer, Susanne; Berntsen, Terje; Chin, Mian; Collins, William D.; hide

    2012-01-01

    The CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) layer product is used for a multimodel evaluation of the vertical distribution of aerosols. Annual and seasonal aerosol extinction profiles are analyzed over 13 sub-continental regions representative of industrial, dust, and biomass burning pollution, from CALIOP 2007-2009 observations and from AeroCom (Aerosol Comparisons between Observations and Models) 2000 simulations. An extinction mean height diagnostic (Z-alpha) is defined to quantitatively assess the models' performance. It is calculated over the 0-6 km and 0-10 km altitude ranges by weighting the altitude of each 100 m altitude layer by its aerosol extinction coefficient. The mean extinction profiles derived from CALIOP layer products provide consistent regional and seasonal specificities and a low inter-annual variability. While the outputs from most models are significantly correlated with the observed Z-alpha climatologies, some do better than others, and 2 of the 12 models perform particularly well in all seasons. Over industrial and maritime regions, most models show higher Z-alpha than observed by CALIOP, whereas over the African and Chinese dust source regions, Z-alpha is underestimated during Northern Hemisphere Spring and Summer. The positive model bias in Z-alpha is mainly due to an overestimate of the extinction above 6 km. Potential CALIOP and model limitations, and methodological factors that might contribute to the differences are discussed.

  3. Airborne Sunphotometer Measurements of Aerosol Optical Depth and Water Vapor in ACE-Asia and Their Comparisons to Correlative Measurements

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Livingston, J.; Russell, P.; Hegg, D.; Wang, J.; Kahn, R.; Hsu, C.; Masonis, S.; Murayama, T.; hide

    2002-01-01

    In the Spring 2001 phase of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), the 6-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) operated on 15 of the 19 research flights of the NCAR C-130, while its 14-channel counterpart (AATS-14) flew successfully on all 19 research flights of the CIRPAS Twin Otter. ACE-Asia studied aerosol outflow from the Asian continent to the Pacific basin. It was designed to integrate suborbital and satellite measurements and models to reduce the uncertainty in calculations of the climate forcing due to aerosols. AATS-6 and AATS-14 measured solar beam transmission at six and 14 wavelengths (380-1021 and 354-1558 nm, respectively), yielding aerosol optical depth (AOD) spectra and columnar water vapor (CWV). Vertical differentiation in profiles yielded aerosol extinction spectra and water vapor concentration. In this paper, we plan to present examples of the following, preliminary findings that are based in part on our airborne sunphotometer measurements: (1) The wavelength dependence of sunphotometer-derived AOD and extinction indicates that supermicron dust was often a major component of the aerosol, frequently extending to high altitudes. The percentage of full-column AOD (525 nm) that Jay above 3 km was typically 34+/-13%. In contrast, the analogous percentage of columnar water vapor was only 10+/-4%; (2) Initial comparison studies between AOD data obtained by AATS-6 and AATS-14 during coordinated low-level flight legs show agreement well within the instruments' error bars; (3) Aerosol extinction has been derived from airborne in situ measurements of scattering (nephelometers) and absorption (particle soot/ absorption photometer, PSAP) or calculated from particle size distribution measurements (mobility analyzers and aerodynamic particle sizers). Comparison with corresponding extinction values derived from the Ames airborne sunphotometer measurements shows good agreement for the vertical distribution

  4. Astronomical Extinction Over The ELT Moroccan Sites From Aerosol Satellite Data

    NASA Astrophysics Data System (ADS)

    Siher, E. A.; Benkhaldoun, Z.; Bounhir, A.

    2006-08-01

    Two Moroccan sites are selected to be characterized for the ELT telescopes. These sites are in the Atlas, between Oukaimeden (where is the national observatory) and The Canaries Islands. For a preliminary study, we will use the TOMS/Nimbus7 aerosol index (AI), threshold 0.7, to extract the astronomical extinction (AE), threshold 0.2 mag/airmass. In fact, on the one hand, one previously work showed the link between these parameters over the Canaries Islands (ORM Observatory). On the other hand, many studies proposed the dust characterization for the future extremely large telescope for a mandatory qualification.

  5. Spatial and temporal variations of aerosols around Beijing in summer 2006: 2. Local and column aerosol optical properties

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Matsui, Hitoshi; Koike, Makoto; Kondo, Yutaka

    Weather Research and Forecasting (WRF)-chem model calculations were conducted to study aerosol optical properties around Beijing, China, during the Campaign of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing-2006) period. In this paper, we interpret aerosol optical properties in terms of aerosol mass concentrations and their chemical compositions by linking model calculations with measurements. In general, model calculations reproduced observed features of spatial and temporal variations of various surface and column aerosol optical parameters in and around Beijing. Spatial and temporal variations of aerosol absorption, scattering, and extinction coefficient corresponded well to those of elemental carbon (primary aerosol),more » sulfate (secondary aerosol), and the total aerosol mass concentration, respectively. These results show that spatial and temporal variations of the absorption coefficient are controlled by local emissions (within 100 km around Beijing during the preceding 24 h), while those of the scattering coefficient are controlled by regional-scale emissions (within 500 km around Beijing during the preceding 3 days) under synoptic-scale meteorological conditions, as discussed in our previous study of aerosol mass concentration. Vertical profiles of aerosol extinction revealed that the contribution of secondary aerosols and their water uptake increased with altitude within the planetary boundary layer, leading to a considerable increase in column aerosol optical depth (AOD) around Beijing. These effects are the main factors causing differences in regional and temporal variations between particulate matter (PM) mass concentration at the surface and column AOD over a wide region in the northern part of the Great North China Plain.« less

  6. Overview of ACE-Asia Spring 2001 Investigations On Aerosol-Radiation Interactions

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Flatau, P. J.; Valero, F. P. J.; Nakajima, T.; Holben, B.; Pilewskie, P.; Bergin, M.; Schmid, B.; Bergstrom, R. W.; Vogelmann, A.; hide

    2002-01-01

    ACE-Asia's extensive measurements from land, ocean, air and space quantified aerosol-radiation interactions. Results from each platform type, plus satellite-suborbital combinations, include: 1. Time series of multiwavelength aerosol optical depth (ADD), Angstrom exponent (alpha), single-scattering albedo (SSA), and size distribution from AERONET radiometry at 13 stations. In China and Korea AOD and alpha were strongly anticorrelated (reflecting transient dust events); dust volume-size modes peaked near 8 microns diameter; and SSA(dust) greater than SSA(pollution). 2. Calculations and measurements of photosynthetically active radiation and aerosols in China yield 24-h average downward surface radiative forcing per AOD(500 nm) of -27 W/sq m (400-700 nm). 3. The Hawaii-Japan cruise sampled a gradient with AOD(500 nm) extremes of 0.1 and 1.1. Shipboard measurements showed that adding dust to pollution increased SSA(550 nm, 55% RH), typically from -0.91 to approx. 0.97. Downwelling 8-12 micron radiances showed aerosol effects, especially in the major April dust event, with longwave forcing estimated at -5 to 15 W/sq m. 4. Extinction profiles from airborne sunphotometry and total-direct-diffuse radiometry show wavelength dependence often varying strongly with height, reflecting layering of dust-dominated over pollution-dominated aerosols. Comparing sunphotometric extinction profiles to those from in situ measurements (number and composition vs size, or scattering and absorption) shows layer heights agree, but extinction sometimes differs. 5. Airborne solar spectral flux radiometry yields absorption spectra for layers. Combining with AOD spectra yields best-fit aerosol single scattering albedo spectra. 6. Visible, NIR and total solar fluxes combined with AOD give radiative forcing efficiencies at surface and aloft.

  7. SAM 2 Measurements of the Polar Stratospheric Aerosol, volume 2. April 1979 to October 1979

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Steele, H. M.; Hamill, P.

    1982-01-01

    The Stratospheric Aerosol Measurement (SAM) II sensor is abroad the Earth orbiting Nimbus 7 spacecraft proving extinction measurements of the Antarctic and Arctic stratospheric aerosol with a vertical resolution of 1 km. Representative examples and weekly averages of aerosol data and corresponding temperature profiles for the time and place of each SAM II measurement (April 29, 1979, to October 27, 1979) is presented. Contours of aerosol extinction as a function of altitude and longitude or time were plotted and weekly aerosol optical depths were calculated. Seasonal variations and variations in space (altitude and longitude) for both polar regions are easily seen. Typical values of aerosol extinction at the SAM II wavelength of 1.0 micron for the time priod were 1 to 3 x 10 to the -4th power km -1 in the main stratospheric aerosol layer. Optical depths for the stratosphere were about 0.002. Polar stratospheric clouds at altitudes between the tropopause and 20 km were observed during the Antarctic winter at various times and locations. A ready-to-use format containing a representative sample of the second 6 months of data to be used in atmospheric and climatic studies is presented.

  8. ACTRIS aerosol vertical profile data and observations: potentiality and first examples of integrated studies with models

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Benedetti, Angela; D'Amico, Giuseppe; Myhre, Cathrine Lund; Schulz, Michael; Wandinger, Ulla; Laj, Paolo; Pappalardo, Gelsomina

    2016-04-01

    The ACTRIS-2 project, funded by Horizon 2020, addresses the scope of integrating state-of-the-art European ground-based stations for long term observations of aerosols, clouds and short lived gases, capitalizing on the work of FP7-ACTRIS. It aims at achieving the construction of a user-oriented RI, unique in the EU-RI landscape for providing 4-D integrated high-quality data from near-surface to high altitude (vertical profiles and total-column) which are relevant to climate and air-quality research. ACTRIS-2 develops and implements, in a large network of stations in Europe and beyond, observational protocols that permit the harmonization of collected data and their dissemination. ACTRIS secures provision and dissemination of a unique set of data and data-products that would not otherwise be available with the same level of quality and standardization. This results from a 10-year plus effort in constructing a research infrastructure capable of responding to community needs and requirements, and has been engaged since the start of the FP5 EU commission program. ACTRIS ensures compliance with reporting requirements (timing, format, traceability) defined by the major global observing networks. EARLINET (European Aerosol research Lidar NETwork), the aerosol vertical profiling component of ACTRIS, is providing since May 2000 vertical profiles of aerosol extinction and backscatter over Europe. A new structure of the EARLINET database has been designed in a more user oriented approach reporting new data products which are more effective for specific uses of different communities. In particular, a new era is starting with the Copernicus program during which the aerosol vertical profiling capability will be fundamental for assimilation and validation purposes. The new data products have been designed thanks to a strong link with EARLINET data users, first of all modeling and satellite communities, established since the beginning of EARLINET and re-enforced within ACTRIS2

  9. Airborne High Spectral Resolution Lidar Aerosol Measurements during MILAGRO and TEXAQS/GOMACCS

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard; Hostetler, Chris; Hair, John; Cook Anthony; Harper, David; Burton, Sharon; Clayton, Marian; Clarke, Antony; Russell, Phil; Redemann, Jens

    2007-01-01

    Two1 field experiments conducted during 2006 provided opportunities to investigate the variability of aerosol properties near cities and the impacts of these aerosols on air quality and radiative transfer. The Megacity Initiative: Local and Global Research Observations (MILAGRO) /Megacity Aerosol Experiment in Mexico City (MAX-MEX)/Intercontinental Chemical Transport Experiment-B (INTEX-B) joint experiment conducted during March 2006 investigated the evolution and transport of pollution from Mexico City. The Texas Air Quality Study (TEXAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) (http://www.al.noaa.gov/2006/) conducted during August and September 2006 investigated climate and air quality in the Houston/Gulf of Mexico region. During both missions, the new NASA Langley airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B200 King Air aircraft and measured profiles of aerosol extinction, backscattering, and depolarization to: 1) characterize the spatial and vertical distributions of aerosols, 2) quantify aerosol extinction and optical thickness contributed by various aerosol types, 3) investigate aerosol variability near clouds, 4) evaluate model simulations of aerosol transport, and 5) assess aerosol optical properties derived from a combination of surface, airborne, and satellite measurements.

  10. SAM-2 ground-truth plan: Correlative measurements for the Stratospheric Aerosol Measurement-2 (SAM 2) sensor on the Nimbus G satellite

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.; Mcmaster, L. R.; Pepin, T. J.; Chu, W. P.; Swissler, T. J.

    1978-01-01

    The SAM-2 will fly aboard the Nimbus-G satellite for launch in the fall of 1978 and measure stratospheric vertical profiles of aerosol extinction in high latitude bands. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. The SAM-2 expected instrument performance and data inversion results are presented. Various atmospheric models representative of polar stratospheric aerosols are used in the SAM-2 and correlative sensor analyses.

  11. SAGE ground truth plan: Correlative measurements for the Stratospheric Aerosol and Gas Experiment (SAGE) on the AEM-B satellite

    NASA Technical Reports Server (NTRS)

    Russell, P. B. (Editor); Cunnold, D. M.; Grams, G. W.; Laver, J.; Mccormick, M. P.; Mcmaster, L. R.; Murcray, D. G.; Pepin, T. J.; Perry, T. W.; Planet, W. G.

    1979-01-01

    The ground truth plan is outlined for correlative measurements to validate the Stratospheric Aerosol and Gas Experiment (SAGE) sensor data. SAGE will fly aboard the Applications Explorer Mission-B satellite scheduled for launch in early 1979 and measure stratospheric vertical profiles of aerosol, ozone, nitrogen dioxide, and molecular extinction between 79 N and 79 S. latitude. The plan gives details of the location and times for the simultaneous satellite/correlative measurements for the nominal launch time, the rationale and choice of the correlative sensors, their characteristics and expected accuracies, and the conversion of their data to extinction profiles. In addition, an overview of the SAGE expected instrument performance and data inversion results are presented. Various atmospheric models representative of stratospheric aerosols and ozone are used in the SAGE and correlative sensor analyses.

  12. Aerosol physical properties in the stratosphere (APPS) radiometer design

    NASA Technical Reports Server (NTRS)

    Gray, C. R.; Woodin, E. A.; Anderson, T. J.; Magee, R. J.; Karthas, G. W.

    1977-01-01

    The measurement concepts and radiometer design developed to obtain earth-limb spectral radiance measurements for the Aerosol Physical Properties in the Stratosphere (APPS) measurement program are presented. The measurements made by a radiometer of this design can be inverted to yield vertical profiles of Rayleigh scatterers, ozone, nitrogen dioxide, aerosol extinction, and aerosol physical properties, including a Junge size-distribution parameter, and a real and imaginary index of refraction. The radiometer design provides the capacity for remote sensing of stratospheric constituents from space on platforms such as the space shuttle and satellites, and therefore provides for global measurements on a daily basis.

  13. Chemical, optical and radiative characteristics of aerosols during haze episodes of winter in the North China Plain

    NASA Astrophysics Data System (ADS)

    Ding, Jing; Zhang, Yufen; Han, Suqin; Xiao, Zhimei; Wang, Jiao; Feng, Yinchang

    2018-05-01

    Aerosol and water vapor radiative forcings, shortwave atmospheric heating rates and longwave atmospheric cooling rates were determined based on in situ physical and chemical measurements of aerosol, associated with the Mie theory and a radiative transfer model, LOWTRAN7, during the two haze episodes in the winter of 2013 in Tianjin, China. The aerosol types considered in LOWTRAN7 included rural, urban, marine, desert and custom aerosols. The default ratio of the absorption coefficient to the extinction coefficient for urban aerosol in LOWTRAN7 was approximately double of those found in this work, implying the weaker absorption ability of aerosols in the North China Plain (NCP). Moreover, the aerosol is assumed to be evenly distributed below 1 km of planetary boundary layer (PBL) on hazy days in LOWTRAN7. If the default urban aerosol optical properties and extinction profile in LOWTRAN7 is employed directly, a larger energy imbalance between the atmosphere and surface is generated and the warming effect of the aerosol is magnified. Hence, modified urban aerosol optical properties were established to replace the corresponding parameters' database in LOWTRAN7. The aerosol extinction profiles were obtained based on a 255-m meteorological tower and observed results from the studies about Tianjin. In the NCP, the aerosol had little impact on atmospheric counter radiation. The water vapor is the crucial factor that affects atmospheric counter radiation. Both modified high shortwave heating rates and longwave cooling rates occur near the surface due to the abundance of aerosol and water vapor. The modified net atmospheric heating rate near the surface is 1.2 K d-1 on hazy days and 0.3 K d-1 on non-hazy days. Compared with the default urban aerosol optical properties and its vertical distribution in LOWTRAN7, the feedback effect of the modified urban aerosol on the boundary layer may not necessarily result in a stable lower atmosphere, but depends on the aerosol light

  14. An effective inversion algorithm for retrieving bimodal aerosol particle size distribution from spectral extinction data

    NASA Astrophysics Data System (ADS)

    He, Zhenzong; Qi, Hong; Yao, Yuchen; Ruan, Liming

    2014-12-01

    The Ant Colony Optimization algorithm based on the probability density function (PDF-ACO) is applied to estimate the bimodal aerosol particle size distribution (PSD). The direct problem is solved by the modified Anomalous Diffraction Approximation (ADA, as an approximation for optically large and soft spheres, i.e., χ⪢1 and |m-1|⪡1) and the Beer-Lambert law. First, a popular bimodal aerosol PSD and three other bimodal PSDs are retrieved in the dependent model by the multi-wavelength extinction technique. All the results reveal that the PDF-ACO algorithm can be used as an effective technique to investigate the bimodal PSD. Then, the Johnson's SB (J-SB) function and the modified beta (M-β) function are employed as the general distribution function to retrieve the bimodal PSDs under the independent model. Finally, the J-SB and M-β functions are applied to recover actual measurement aerosol PSDs over Beijing and Shanghai obtained from the aerosol robotic network (AERONET). The numerical simulation and experimental results demonstrate that these two general functions, especially the J-SB function, can be used as a versatile distribution function to retrieve the bimodal aerosol PSD when no priori information about the PSD is available.

  15. Explicit and Observation-based Aerosol Treatment in Tropospheric NO2 Retrieval over China from the Ozone Monitoring Instrument

    NASA Astrophysics Data System (ADS)

    Liu, M.; Lin, J.; Boersma, F.; Pinardi, G.; Wang, Y.; Chimot, J.; Wagner, T.; Xie, P.; Eskes, H.; Van Roozendael, M.; Hendrick, F.

    2017-12-01

    Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is influenced by aerosols substantially. Aerosols affect the retrieval of "effective cloud fraction (CF)" and "effective cloud top pressure (CP)" that are used in the subsequent NO2 retrieval to account for the presentence of clouds. And aerosol properties and vertical distributions directly affect the NO2 air mass factor (AMF) calculations. Our published POMINO algorithm uses a parallelized LIDORT-driven AMFv6 code to derive CF, CP and NO2 VCD. Daily information on aerosol optical properties are taken from GEOS-Chem simulations, with aerosol optical depth (AOD) further constrained by monthly MODIS AOD. However, the published algorithm does not include an observation-based constraint of aerosol vertical distribution. Here we construct a monthly climatological observation dataset of aerosol extinction profiles, based on Level-2 CALIOP data over 2007-2015, to further constrain aerosol vertical distributions. GEOS-Chem captures the temporal variations of CALIOP aerosol layer heights (ALH) but has an overall underestimate by about 0.3 km. It tends to overestimate the aerosol extinction by 10% below 2 km but with an underestimate by 30% above 2 km, leading to a low bias by 10-30% in the retrieved tropospheric NO2 VCD. After adjusting GEOS-Chem aerosol extinction profiles by the CALIOP monthly ALH climatology, the retrieved NO2 VCDs increase by 4-16% over China on a monthly basis in 2012. The improved NO2 VCDs are better correlated to independent MAX-DOAS observations at three sites than POMINO and DOMINO are - especially for the polluted cases, R2 reaches 0.76 for the adjusted POMINO, much higher than that for the published POMINO (0.68) and DOMINO (0.38). The newly retrieved CP increases by 60 hPa on average, because of a stronger aerosol screening effect. Compared to the CF used in DOMINO, which implicitly includes aerosol information, our improved CF is much lower and can

  16. CATS Cloud and Aerosol Level 2 Heritage Edition Data Products.

    NASA Astrophysics Data System (ADS)

    Rodier, S. D.; Vaughan, M.; Yorks, J. E.; Palm, S. P.; Selmer, P. A.; Hlavka, D. L.; McGill, M. J.; Trepte, C. R.

    2017-12-01

    The Cloud-Aerosol Transport System (CATS) instrument was developed at NASA's Goddard Space Flight Center (GSFC) and deployed to the International Space Station (ISS) in January 2015. The CATS elastic backscatter lidars have been operating continuously in one of two science modes since February 2015. One of the primary science objectives of CATS is to continue the CALIPSO aerosol and cloud profile data record to provide continuity of lidar climate observations during the transition from CALIPSO to EarthCARE. To accomplish this, the CATS project at NASA's Goddard Space Flight Center (GSFC) and the CALIPSO project at NASA's Langley Research Center (LaRC) closely collaborated to develop and deliver a full suite of CALIPSO-like level 2 data products using the latest version of the CALIPSO level 2 Version 4 algorithms for the CATS data acquired while operating in science mode 1 (Multi-beam backscatter detection at 1064 and 532 nm, with depolarization measurement at both wavelengths). In this work, we present the current status of the CATS Heritage (i.e. CALIPSO-like) level 2 data products derived from the recent released CATS Level 1B V2-08 data. Extensive comparisons are performed between the three data sets (CALIPSO V4.10 Level 2, CATS Level 2 Operational V2-00 and CATS Heritage V1.00) for cloud and aerosol measurements (e.g., cloud-top height cloud-phase, cloud-layer occurrence frequency and cloud-aerosol discrimination) along the ISS path. In addition, global comparisons (between 52°S and 52°N) of aerosol extinction profiles derived from the CATS Level 2 Operational products and CALIOP V4 Level 2 products are presented. Comparisons of aerosol optical depths retrieved from active sensors (CATS and CALIOP) and passive sensors (MODIS) will provide context for the extinction profile comparisons.

  17. CALIPSO-Inferred Aerosol Direct Radiative Effects: Bias Estimates Using Ground-Based Raman Lidars

    NASA Technical Reports Server (NTRS)

    Thorsen, Tyler; Fu, Qiang

    2016-01-01

    Observational constraints on the change in the radiative energy budget caused by the presence of aerosols, i.e. the aerosol direct radiative effect (DRE), have recently been made using observations from the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO). CALIPSO observations have the potential to provide improved global estimates of aerosol DRE compared to passive sensor-derived estimates due to CALIPSO's ability to perform vertically-resolved aerosol retrievals over all surface types and over cloud. In this study we estimate the uncertainties in CALIPSO-inferred aerosol DRE using multiple years of observations from the Atmospheric Radiation Measurement (ARM) program's Raman lidars (RL) at midlatitude and tropical sites. Examined are assumptions about the ratio of extinction-to-backscatter (i.e. the lidar ratio) made by the CALIPSO retrievals, which are needed to retrieve the aerosol extinction profile. The lidar ratio is shown to introduce minimal error in the mean aerosol DRE at the top-of-atmosphere and surface. It is also shown that CALIPSO is unable to detect all radiatively-significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE by 30-50%. Therefore, global estimates of the aerosol DRE inferred from CALIPSO observations are likely too weak.

  18. CALIPSO-Inferred Aerosol Direct Radiative Effects: Bias Estimates Using Ground-Based Raman Lidars

    NASA Technical Reports Server (NTRS)

    Thorsen, Tyler; Fu, Qiang

    2015-01-01

    Observational constraints on the change in the radiative energy budget caused by the presence of aerosols, i.e. the aerosol direct radiative effect (DRE), have recently been made using observations from the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite (CALIPSO). CALIPSO observations have the potential to provide improved global estimates of aerosol DRE compared to passive sensor-derived estimates due to CALIPSO's ability to perform vertically-resolved aerosol retrievals over all surface types and over cloud. In this study we estimate the uncertainties in CALIPSO-inferred aerosol DRE using multiple years of observations from the Atmospheric Radiation Measurement (ARM) program's Raman lidars (RL) at mid-latitude and tropical sites. Examined are assumptions about the ratio of extinction-to-backscatter (i.e. the lidar ratio) made by the CALIPSO retrievals, which are needed to retrieve the aerosol extinction profile. The lidar ratio is shown to introduce minimal error in the mean aerosol DRE at the top-of-atmosphere and surface. It is also shown that CALIPSO is unable to detect all radiatively-significant aerosol, resulting in an underestimate in the magnitude of the aerosol DRE by 30â€"50%. Therefore, global estimates of the aerosol DRE inferred from CALIPSO observations are likely too weak.

  19. Ground-Based Lidar Measurements of Aerosols During ACE-2 Instrument Description, Results, and Comparisons with Other Ground-Based and Airborne Measurements

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Maring, Hal; Smirnov, Alexander; Holben, Brent; Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.; hide

    2000-01-01

    A micro-pulse lidar system (MPL) was used to measure the vertical and horizontal distribution or aerosols during the Aerosol Characterization Experiment 2 (ACE-2) in June and July of 1997. The MPL measurements were made at the Izana observatory (IZO), a weather station located on a mountain ridge (28 deg 18'N, 16 deg 30'W, 2367 m asl) near the center of the island of Tenerife, Canary Islands. The MPL was used to acquire aerosol backscatter, extinction, and optical depth profiles for normal background periods and periods influenced by Saharan dust from North Africa. System tests and calibration procedures are discussed, and in analysis of aerosol optical profiles acquired during ACE-2 is presented. MPL data taken during normal IZO conditions (no dust) showed that upslope aerosols appeared during the day and dissipated at night and that the layers were mostly confined to altitudes a few hundred meters above IZO. MPL data taken during a Saharan dust episode on 17 July showed that peak aerosol extinction values were an order of magnitude greater than molecular scattering over IZO. and that the dust layers extended to 5 km asl. The value of the dust backscatter-extinction ratio was determined to be 0.027 + 0.007 per sr. Comparisons of the MPL data with data from other co-located instruments showed good agreement during the dust episode.

  20. Ground-Based Lidar Measurements of Aerosols During ACE-2: Instrument Description, Results, and Comparisons with Other Ground-Based and Airborne Measurements

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Voss, Kenneth J.; Gordon, Howard R.; Maring, Hal; Smirnov, Alexander; Holben, Brent; Schmid, Beat; Livingston, John M.; Russell, Philip B.; Durkee, Philip A.

    2000-01-01

    A micro-pulse lidar system (MPL) was used to measure the vertical and horizontal distribution of aerosols during the Aerosol Characterization Experiment 2 (ACE-2) in June and July of 1997. The MPL measurements were made at the Izana observatory (IZO), a weather station located on a mountain ridge (28 deg 18 min N, 16 deg 30 min W, 2367 m asl) near the center of the island of Tenerife, Canary Islands. The MPL was used to acquire aerosol backscatter, extinction, and optical depth profiles for normal background periods and periods influenced by Saharan dust from North Africa. System tests and calibration procedures are discussed, and an analysis of aerosol optical profiles acquired during ACE-2 is presented. MPL data taken during normal IZO conditions (no dust) showed that upslope aerosols appeared during the day and dissipated at night and that the layers were mostly confined to altitudes a few hundred meters above IZO. MPL data taken during a Saharan dust episode on 17 July showed that peak aerosol extinction values were an order of magnitude greater than molecular scattering over IZO, and that the dust layers extended to 5 km asl. The value of the dust backscatter-extinction ratio was determined to be 0.027 +/- 0.007 sr(exp -1). Comparisons of the MPL data with data from other collocated instruments showed good agreement during the dust episode.

  1. High-latitude stratospheric aerosols measured by the SAM II satellite system in 1978 and 1979

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Chu, W. P.; Mcmaster, L. R.; Grams, G. W.; Hamill, P.; Steele, H. M.; Swissler, T. J.; Herman, B. M.; Pepin, T. J.; Russell, P. B.

    1981-01-01

    Results of the first year of data collection by the SAM (Stratospheric Aerosol Measurement) II satellite system are presented. Almost 10,000 profiles of stratospheric aerosol extinction in the Arctic and Antarctic regions are used to construct plots of weekly averaged aerosol extinction versus altitude and time and stratospheric optical depth versus time. Corresponding temperature fields are presented. These data show striking similarities in the aerosol behavior for corresponding seasons. Wintertime polar stratospheric clouds that are strongly correlated with temperature are documented. They are much more prevalent in the Antarctic stratosphere during the cold austral winter and increase the stratospheric optical depths by as much as an order of magnitude for a period of about 2 months. These clouds might represent a sink for stratospheric water vapor and must be considered in the radiative budget for this region and time.

  2. Reconciling aerosol light extinction measurements from spaceborne lidar observations and in-situ measurements in the Arctic

    NASA Astrophysics Data System (ADS)

    Tesche, M.; Rastak, N.; Charlson, R. J.; Glantz, P.; Zieger, P.; Hansson, H.-C.

    2014-03-01

    In this study we investigate to what degree it is possible to reconcile continuously recorded particle light extinction coefficients derived from dry in-situ measurements at Zeppelin station (78.92° N, 11.85° E, 475 m a.s.l.) at Ny-Ålesund, Svalbard, that are recalculated to ambient relative humidity, and simultaneous ambient observations with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite. To our knowledge, this represents the first study that compares spaceborne lidar measurements to optical aerosol properties from short-term in-situ observations (averaged over 5 h) on a case-by-case basis. Finding suitable comparison cases requires an elaborate screening and matching of the CALIOP data with respect to the location of the Zeppelin station as well as in the selection of temporal and spatial averaging intervals for both the ground-based and spaceborne observations. Trustworthy reconciliation of these data cannot be achieved with the closest approach method that is often used in matching CALIOP observations to those taken at ground sites due to the transport pathways of the air parcels that were sampled. The use of trajectories allowed us to establish a connection between spaceborne and ground-based observations for 57 individual overpasses out of a total of 2018 that occurred in our region of interest around Svalbard (0 to 25° E; 75 to 82° N) in the considered year of 2008. Matches could only be established during winter and spring, since the low aerosol load during summer in connection with the strong solar background and the high occurrence rate of clouds strongly influences the performance and reliability of CALIOP observations. Extinction coefficients in the range from 1 to 100 Mm-1 were found for successful matches with an agreement of a factor of 1.85 (median value for a range from 0.38 to 17.9) between the findings of in-situ and spaceborne

  3. Hemispheric aerosol vertical profiles: anthropogenic impacts on optical depth and cloud nuclei.

    PubMed

    Clarke, Antony; Kapustin, Vladimir

    2010-09-17

    Understanding the effect of anthropogenic combustion upon aerosol optical depth (AOD), clouds, and their radiative forcing requires regionally representative aerosol profiles. In this work, we examine more than 1000 vertical profiles from 11 major airborne campaigns in the Pacific hemisphere and confirm that regional enhancements in aerosol light scattering, mass, and number are associated with carbon monoxide from combustion and can exceed values in unperturbed regions by more than one order of magnitude. Related regional increases in a proxy for cloud condensation nuclei (CCN) and AOD imply that direct and indirect aerosol radiative effects are coupled issues linked globally to aged combustion. These profiles constrain the influence of combustion on regional AOD and CCN suitable for challenging climate model performance and informing satellite retrievals.

  4. Raman Lidar Measurements of Aerosol Optical Properties Performed at CNR- IMAA

    NASA Astrophysics Data System (ADS)

    Mona, L.; Amodeo, A.; Cornacchia, C.; D'Amico, G.; Madonna, F.; Pandolfi, M.; Pappalardo, G.

    2005-12-01

    The lidar system for tropospheric aerosol study, located at CNR-IMAA in Tito Scalo, Potenza (40 °36'N, 15°44' E, 760 m above sea level), is a Raman/elastic lidar system operational since May 2000 in the framework of EARLINET (European Aerosol Research LIdar NETwork), the first lidar network for tropospheric aerosol study on continental scale. It provides independent measurements of aerosol extinction and backscatter coefficient profiles at 355 nm and aerosol backscatter profiles at 532 nm. Both the IMAA aerosol lidar system and the used algorithms for the retrieval of aerosol optical parameters have been successfully tested with different intercomparison exercises in the frame of the EARLINET quality assurance program. In the frame of EARLINET, regular measurements are performed three times per week, allowing to study the aerosol content typically present in the planetary boundary layer over Potenza. Particular attention is devoted to Saharan dust intrusions in Europe, and Saharan dust forecasts are distributed to all EARLINET stations. The large dataset of Saharan dust optical properties profiles collected at IMAA allowed to study the contribution of dust particles to the aerosol load typically present in our area as well as to investigate transformations of aerosol optical properties during the transport. Several intensive measurement campaigns have been performed at IMAA with this system to study optical properties of different types of aerosol, and how the transport and modification mechanisms and the water content affect these optical properties. In particular, direct transport of volcanic aerosol emitted in 2002 during the Etna eruptions was observed, and in summer 2004, aerosol layers related to forest fires smoke or pollution plume transported from Alaska, Canada and North America were observed at IMAA during the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign. Moreover, this system has been used

  5. Determination of nocturnal aerosol properties from a combination of lunar photometer and lidar observations

    NASA Astrophysics Data System (ADS)

    Li, Donghui; Li, Zhengqiang; Lv, Yang; Zhang, Ying; Li, Kaitao; Xu, Hua

    2015-10-01

    Aerosol plays a key role in the assessment of global climate change and environmental health, while observation is one of important way to deepen the understanding of aerosol properties. In this study, the newly instrument - lunar photometer is used to measure moonlight and nocturnal column aerosol optical depth (AOD, τ) is retrieved. The AOD algorithm is test and verified with sun photometer both in high and low aerosol loading. Ångström exponent (α) and fine/coarse mode AOD (τf, τc) 1 is derived from spectral AOD. The column aerosol properties (τ, α, τf, τc) inferred from the lunar photometer is analyzed based on two month measurement in Beijing. Micro-pulse lidar has advantages in retrieval of aerosol vertical distribution, especially in night. However, the typical solution of lidar equation needs lidar ratio(ratio of aerosol backscatter and extinction coefficient) assumed in advance(Fernald method), or constrained by AOD2. Yet lidar ratio is varied with aerosol type and not easy to fixed, and AOD is used of daylight measurement, which is not authentic when aerosol loading is different from day and night. In this paper, the nocturnal AOD measurement from lunar photometer combined with mie scattering lidar observations to inverse aerosol extinction coefficient(σ) profile in Beijing is discussed.

  6. Retrieval of aerosol profiles combining sunphotometer and ceilometer measurements in GRASP code

    NASA Astrophysics Data System (ADS)

    Román, R.; Benavent-Oltra, J. A.; Casquero-Vera, J. A.; Lopatin, A.; Cazorla, A.; Lyamani, H.; Denjean, C.; Fuertes, D.; Pérez-Ramírez, D.; Torres, B.; Toledano, C.; Dubovik, O.; Cachorro, V. E.; de Frutos, A. M.; Olmo, F. J.; Alados-Arboledas, L.

    2018-05-01

    In this paper we present an approach for the profiling of aerosol microphysical and optical properties combining ceilometer and sun/sky photometer measurements in the GRASP code (General Retrieval of Aerosol and Surface Properties). For this objective, GRASP is used with sun/sky photometer measurements of aerosol optical depth (AOD) and sky radiances, both at four wavelengths and obtained from AErosol RObotic NETwork (AERONET), and ceilometer measurements of range corrected signal (RCS) at 1064 nm. A sensitivity study with synthetic data evidences the capability of the method to retrieve aerosol properties such as size distribution and profiles of volume concentration (VC), especially for coarse particles. Aerosol properties obtained by the mentioned method are compared with airborne in-situ measurements acquired during two flights over Granada (Spain) within the framework of ChArMEx/ADRIMED (Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region) 2013 campaign. The retrieved aerosol VC profiles agree well with the airborne measurements, showing a mean bias error (MBE) and a mean absolute bias error (MABE) of 0.3 μm3/cm3 (12%) and 5.8 μm3/cm3 (25%), respectively. The differences between retrieved VC and airborne in-situ measurements are within the uncertainty of GRASP retrievals. In addition, the retrieved VC at 2500 m a.s.l. is shown and compared with in-situ measurements obtained during summer 2016 at a high-atitude mountain station in the framework of the SLOPE I campaign (Sierra Nevada Lidar AerOsol Profiling Experiment). VC from GRASP presents high correlation (r = 0.91) with the in-situ measurements, but overestimates them, MBE and MABE being equal to 23% and 43%.

  7. Light extinction in the atmosphere

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Laulainen, N.

    1992-06-01

    Atmospheric aerosol particles originating from natural sources, such as volcanos and sulfur-bearing gas emissions from the oceans, and from human sources, such as sulfur emissions from fossil fuel combustion and biomass burning, strongly affect visual air quality and are suspected to significantly affect radiative climate forcing of the planet. During the daytime, aerosols obscure scenic vistas, while at night they diminish our ability to observe stellar objects. Scattering of light is the main means by which aerosols attenuate and redistribute light in the atmosphere and by which aerosols can alter and reduce visibility and potentially modify the energy balance ofmore » the planet. Trends and seasonal variability of atmospheric aerosol loading, such as column-integrated light extinction or optical depth, and how they may affect potential climate change have been difficult to quantify because there have been few observations made of important aerosol optical parameters, such as optical depth, over the globe and over time and often these are of uneven quality. To address questions related to possible climate change, there is a pressing need to acquire more high-quality aerosol optical depth data. Extensive deployment of improved solar radiometers over the next few years will provide higher-quality extinction data over a wider variety of locations worldwide. An often overlooked source of turbidity data, however, is available from astronomical observations, particularly stellar photoelectric photometry observations. With the exception of the Project ASTRA articles published almost 20 years ago, few of these data ever appear in the published literature. This paper will review the current status of atmospheric extinction observations, as highlighted by the ASTRA work and augmented by more recent solar radiometry measurements.« less

  8. Strengths and limitations of the NATALI code for aerosol typing from multiwavelength Raman lidar observations

    NASA Astrophysics Data System (ADS)

    Nicolae, Doina; Talianu, Camelia; Vasilescu, Jeni; Nicolae, Victor; Stachlewska, Iwona S.

    2018-04-01

    A Python code was developed to automatically retrieve the aerosol type (and its predominant component in the mixture) from EARLINET's 3 backscatter and 2 extinction data. The typing relies on Artificial Neural Networks which are trained to identify the most probable aerosol type from a set of mean-layer intensive optical parameters. This paper presents the use and limitations of the code with respect to the quality of the inputed lidar profiles, as well as with the assumptions made in the aerosol model.

  9. Trends in sulfate and organic aerosol mass in the Southeast U.S.: Impact on aerosol optical depth and radiative forcing

    NASA Astrophysics Data System (ADS)

    Attwood, A. R.; Washenfelder, R. A.; Brock, C. A.; Hu, W.; Baumann, K.; Campuzano-Jost, P.; Day, D. A.; Edgerton, E. S.; Murphy, D. M.; Palm, B. B.; McComiskey, A.; Wagner, N. L.; Sá, S. S.; Ortega, A.; Martin, S. T.; Jimenez, J. L.; Brown, S. S.

    2014-11-01

    Emissions of SO2 in the United States have declined since the early 1990s, resulting in a decrease in aerosol sulfate mass in the Southeastern U.S. of -4.5(±0.9)% yr-1 between 1992 and 2013. Organic aerosol mass, the other major aerosol component in the Southeastern U.S., has decreased more slowly despite concurrent emission reductions in anthropogenic precursors. Summertime measurements in rural Alabama quantify the change in aerosol light extinction as a function of aerosol composition and relative humidity. Application of this relationship to composition data from 2001 to 2013 shows that a -1.1(±0.7)% yr-1 decrease in extinction can be attributed to decreasing aerosol water mass caused by the change in aerosol sulfate/organic ratio. Calculated reductions in extinction agree with regional trends in ground-based and satellite-derived aerosol optical depth. The diurnally averaged summertime surface radiative effect has changed by 8.0 W m-2, with 19% attributed to the decrease in aerosol water.

  10. Biomass burning aerosols characterization from ground based and profiling measurements

    NASA Astrophysics Data System (ADS)

    Marin, Cristina; Vasilescu, Jeni; Marmureanu, Luminita; Ene, Dragos; Preda, Liliana; Mihailescu, Mona

    2018-04-01

    The study goal is to assess the chemical and optical properties of aerosols present in the lofted layers and at the ground. The biomass burning aerosols were evaluated in low level layers from multi-wavelength lidar measurements, while chemical composition at ground was assessed using an Aerosol Chemical Speciation Monitor (ACSM) and an Aethalometer. Classification of aerosol type and specific organic markers were used to explore the potential to sense the particles from the same origin at ground base and on profiles.

  11. Aerosol and Cloud Interaction Observed From High Spectral Resolution Lidar Data

    NASA Technical Reports Server (NTRS)

    Su, Wenying; Schuster, Gregory L.; Loeb, Norman G.; Rogers, Raymond R.; Ferrare, Richard A.; Hostetler, Chris A.; Hair, Johnathan W.; Obland, Michael D.

    2008-01-01

    Recent studies utilizing satellite retrievals have shown a strong correlation between aerosol optical depth (AOD) and cloud cover. However, these retrievals from passive sensors are subject to many limitations, including cloud adjacency (or 3D) effects, possible cloud contamination, uncertainty in the AOD retrieval. Some of these limitations do not exist in High Spectral Resolution Lidar (HSRL) observations; for instance, HSRL observations are not a ected by cloud adjacency effects, are less prone to cloud contamination, and offer accurate aerosol property measurements (backscatter coefficient, extinction coefficient, lidar ratio, backscatter Angstrom exponent,and aerosol optical depth) at a neospatial resolution (less than 100 m) in the vicinity of clouds. Hence, the HSRL provides an important dataset for studying aerosol and cloud interaction. In this study, we statistically analyze aircraft-based HSRL profiles according to their distance from the nearest cloud, assuring that all profile comparisons are subject to the same large-scale meteorological conditions. Our results indicate that AODs from HSRL are about 17% higher in the proximity of clouds (approximately 100 m) than far away from clouds (4.5 km), which is much smaller than the reported cloud 3D effect on AOD retrievals. The backscatter and extinction coefficients also systematically increase in the vicinity of clouds, which can be explained by aerosol swelling in the high relative humidity (RH) environment and/or aerosol growth through in cloud processing (albeit not conclusively). On the other hand, we do not observe a systematic trend in lidar ratio; we hypothesize that this is caused by the opposite effects of aerosol swelling and aerosol in-cloud processing on the lidar ratio. Finally, the observed backscatter Angstrom exponent (BAE) does not show a consistent trend because of the complicated relationship between BAE and RH. We demonstrate that BAE should not be used as a surrogate for Angstrom

  12. Aerosol Measurements by the Globally Distributed Micro Pulse Lidar Network

    NASA Technical Reports Server (NTRS)

    Spinhirne, James; Welton, Judd; Campbell, James; Berkoff, Tim; Starr, David (Technical Monitor)

    2001-01-01

    Full time measurements of the vertical distribution of aerosol are now being acquired at a number of globally distributed MP (micro pulse) lidar sites. The MP lidar systems provide full time profiling of all significant cloud and aerosol to the limit of signal attenuation from compact, eye safe instruments. There are currently eight sites in operation and over a dozen planned. At all sited there are also passive aerosol and radiation measurements supporting the lidar data. Four of the installations are at Atmospheric Radiation Measurement program sites. The network operation includes instrument operation and calibration and the processing of aerosol measurements with standard retrievals and data products from the network sites. Data products include optical thickness and extinction cross section profiles. Application of data is to supplement satellite aerosol measurements and to provide a climatology of the height distribution of aerosol. The height distribution of aerosol is important for aerosol transport and the direct scattering and absorption of shortwave radiation in the atmosphere. Current satellite and other data already provide a great amount of information on aerosol distribution, but no passive technique can adequately resolve the height profile of aerosol. The Geoscience Laser Altimeter System (GLAS) is an orbital lidar to be launched in early 2002. GLAS will provide global measurements of the height distribution of aerosol. The MP lidar network will provide ground truth and analysis support for GLAS and other NASA Earth Observing System data. The instruments, sites, calibration procedures and standard data product algorithms for the MPL network will be described.

  13. The concept of apparent polarizability for calculating the extinction of electromagnetic radiation by porous aerosol particles

    NASA Astrophysics Data System (ADS)

    Haspel, C.; Adler, G.

    2017-04-01

    In the current study, the electromagnetic properties of porous aerosol particles are calculated in two ways. In the first, a porous target input file is generated by carving out voids in an otherwise homogeneous particle, and the discrete dipole approximation (DDA) is used to compute the extinction efficiency of the particle assuming that the voids are near vacuum dielectrics and assuming random particle orientation. In the second, an effective medium approximation (EMA) style approach is employed in which an apparent polarizability of the voids is defined based on the well-known solution to the problem in classical electrostatics of a spherical cavity within a dielectric. It is found that for porous particles with smaller overall diameter with respect to the wavelength of incident radiation, describing the voids as near vacuum dielectrics within the DDA sufficiently reproduces measured values of extinction efficiency, whereas for porous particles with moderate to larger overall diameters with respect to the wavelength of the radiation, the apparent polarizability EMA approach better reproduces the measured values of extinction efficiency.

  14. Verification of the naval oceanic vertical aerosol model during FIRE

    NASA Technical Reports Server (NTRS)

    Davidson, K. L.; Deleeuw, G.; Gathman, S. G.; Jensen, D. R.

    1990-01-01

    The value of Naval Oceanic Vertical Aerosol Model (NOVAM) is illustrated for estimating the non-uniform and non-logarithmic extinction profiles, based on a severe test involving conditions close to and beyond the limits of applicability of NOVAM. A more comprehensive evaluation of NOVAM from the FIRE data is presented, which includes a clear-air case. For further evaluation more data are required on the vertical structure of the extinction in the marine atmospheric boundary layer (MABL), preferably for different meteorological conditions and in different geographic areas (e.g., ASTEX).

  15. 1984-1995 Evolution of Stratospheric Aerosol Size, Surface Area, and Volume Derived by Combining SAGE II and CLAES Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Bauman, Jill J.

    2000-01-01

    This SAGE II Science Team task focuses on the development of a multi-wavelength, multi- sensor Look-Up-Table (LUT) algorithm for retrieving information about stratospheric aerosols from global satellite-based observations of particulate extinction. The LUT algorithm combines the 4-wavelength SAGE II extinction measurements (0.385 <= lambda <= 1.02 microns) with the 7.96 micron and 12.82 micron extinction measurements from the Cryogenic Limb Array Etalon Spectrometer (CLAES) instrument, thus increasing the information content available from either sensor alone. The algorithm uses the SAGE II/CLAES composite spectra in month-latitude-altitude bins to retrieve values and uncertainties of particle effective radius R(sub eff), surface area S, volume V and size distribution width sigma(sub g).

  16. An Algorithm for the Vertical Structure of Aerosol Extinction in the Lowest Kilometer of the Atmosphere: Rev. 1

    DTIC Science & Technology

    2017-11-01

    inversion layer, or the well-mixed boundary layer. In such cases a low cloud ceiling is not present. In all instances the atmospheric extinction profiles...height, radiation fog depth, or the inversion layer height. The visibility regions and several representative vertical profiles of extinction are...the coefficient B can be found by B = ln(D/A) . (2) The coefficient B is sometimes a function of the cloud ceiling height, the inversion layer height

  17. An Investigation of Aerosol and Ozone Measurements from the Cryogenic Limb Array Etalon Spectrometer: Validation and Relation to Other Chemical Species

    NASA Technical Reports Server (NTRS)

    Deshler, Terry

    1997-01-01

    Throughout this study we focused on comparisons of CLAES and in situ measurements of ozone and aerosol extinction. Thus the comparison is between satellite data representative of large spatial regions and in situ data representative of nearly point samples. Both instruments provide vertical profiles, but the region of overlap is limited to between approximately 10 and 100 mb. CLAES Version 7 ozone measurements have been compared to electrochemical cell ozonesonde measurements over McMurdo Station, Antarctica (78 deg S, 167 deg E), Dumont d'Urville, Antarctica (66.7 deg S, 140 deg E), Laramie, Wyoming (41 deg N, 106 deg W), and Bear Island, Norway (74.3 deg N, 19 deg E). Comparisons were made between vertical ozone profiles, and between integrated column ozone over the region of overlap of the measurements. Comparisons using CLAES Version 8 data are underway. CLAES Version 8 aerosol extinction measurements at all wavelengths have also been compared to University of Wyoming aerosol extinctions over McMurdo Station, Antarctica, and over Laramie, Wyoming. Coincidences in all cases were determined by minimizing the distance between the CLAES observations and the surface station, and the time separation between the satellite and in situ measurements.

  18. Atmospheric soundings by SPICAM occultation observations: aerosol and ozone vertical profiles

    NASA Astrophysics Data System (ADS)

    Montmessin, F.

    2005-12-01

    The SPICAM instrument is a highly versatile, dual spectrometer probing both the UV and the NIR spectral region and is currently flying around Mars onboard Mars Express. Since the beginning of MEx operations, SPICAM has collected about thousand atmospheric profiles while observing in a solar or a stellar occultation mode. UV spectra bear the signatures of several species; i.e carbon dioxide, ozone and aerosols, while infrared spectra potentially bring information on atmospheric condensates and on water vapor. This presentation will focus on the measured aerosol, ozone and water vapor profiles. For the aerosol, we will emphasize the numerous observations made in the polar night and will also discuss some high altitude clouds discovered in the southern hemisphere. Ozone and water vapor profiles will be presented along with some General Circulation Model comparisons. This work has been supported by CNES.

  19. The Global Ozone and Aerosol Profiles and Aerosol Hygroscopic Effect and Absorption Optical Depth (GOA2HEAD) Network Initiative

    NASA Astrophysics Data System (ADS)

    Gao, R. S.; Elkins, J. W.; Frost, G. J.; McComiskey, A. C.; Murphy, D. M.; Ogren, J. A.; Petropavlovskikh, I. V.; Rosenlof, K. H.

    2014-12-01

    Inverse modeling using measurements of ozone (O3) and aerosol is a powerful tool for deriving pollutant emissions. Because they have relatively long lifetimes, O3 and aerosol are transported over large distances. Frequent and globally spaced vertical profiles rather than ground-based measurements alone are therefore highly desired. Three requirements necessary for a successful global monitoring program are: Low equipment cost, low operation cost, and reliable measurements of known uncertainty. Conventional profiling using aircraft provides excellent data, but is cost prohibitive on a large scale. Here we describe a new platform and instruments meeting all three global monitoring requirements. The platform consists of a small balloon and an auto-homing glider. The glider is released from the balloon at about 5 km altitude, returning the light instrument package to the launch location, and allowing for consistent recovery of the payload. Atmospheric profiling can be performed either during ascent or descent (or both) depending on measurement requirements. We will present the specifications for two instrument packages currently under development. The first measures O3, RH, p, T, dry aerosol particle number and size distribution, and aerosol optical depth. The second measures dry aerosol particle number and size distribution, and aerosol absorption coefficient. Other potential instrument packages and the desired spatial/temporal resolution for the GOA2HEAD monitoring initiative will also be discussed.

  20. Stratospheric Aerosol and Gas Experiments 1 and 2: Comparisons with ozonesondes

    NASA Technical Reports Server (NTRS)

    Veiga, Robert E.; Cunnold, Derek M.; Chu, William P.; McCormick, M. Patrick

    1995-01-01

    Ozone profiles measured by the Stratospheric Aerosol and Gas Experiments (SAGE) 1 and 2 are compared with ozonesonde profiles at 24 stations over the period extending from 1979 through 1991. Ozonesonde/satellite differences at 21 stations with SAGE 2 overpasses were computed down to 11.5 km in midlatitudes, to 15.5 km in the lower latitudes, and for nine stations with SAGE 1 overpasses down to 15.5 km. The set of individual satellite and ozonesonde profile comparisons most closely colocated in time and space shows mean absolute differences relative to the satellite measurement of 6 +/- 2% for SAGE 2 and 8 +/- 3% for SAGE 1. The ensemble of ozonesonde/satellite differences, when averaged over all altitudes, shows that for SAGE 2, 70% were less than 5%, whereas for SAGE 1, 50% were less than 5%. The best agreement occurred in the altitude region near the ozone density maximum where almost all the relative differences were less than 5%. Most of the statistically significant differences occurred below the ozone maximum down to the tropopause in the region of steepest ozone gradients and typically ranged between 0 and -20%. Correlations between ozone and aerosol extinction in the northern midlatitudes indicate that aerosols had no discernible impact on the ozonesonde/satellite differences and on the SAGE 2 ozone retrieval for the levels of extinction encountered in the lower stratosphere during 1984 to mid-1991.

  1. Seasonality of Aerosols the Southeastern United States

    NASA Astrophysics Data System (ADS)

    Ford, B. J.; Heald, C. L.

    2012-12-01

    Previous studies have suggested that increases in atmospheric aerosols of biogenic origin may have caused regional cooling over the southeastern United States in recent decades. Understanding the sources and behaviors of these aerosols is important for determining their role in a changing climate and managing their air quality impacts. In this study, we investigate the strong seasonality in aerosol optical depth (AOD) observed by MODIS, MISR, and CALIOP instruments over the southeastern United States and show that this is not simulated by a chemical transport model (GEOS-Chem). However, the model does reproduce surface PM 2.5 concentrations in the region as reported by the IMPROVE and Southeastern Aerosol Research and Characterization (SEARCH) networks, as well as the muted seasonality of these concentrations. In addition, these surface measurements show that organic aerosol makes up a small fraction of total PM 2.5 and has relatively little seasonality, which calls into question the importance of biogenic aerosol as a driver for climate change in the region. Sounding profiles and ground observations of relative humidity suggest that the magnitude of seasonality in AOD cannot be explained by seasonal differences in the hygroscopic growth of aerosols. CALIOP measurements of the vertical profile of aerosol extinction confirm that the likely reconciliation of the differences in seasonality between the surface PM 2.5 and AOD observations is the formation of aerosol aloft, a process not captured by the model. These findings provide initial insights for the Southern Oxidant and Aerosol Study (SOAS) campaign in 2013 which aims to investigate the anthropogenic influence on biogenic aerosol formation in the Southeastern US and elucidate the impact on regional climate and air quality.

  2. MPL-Net Measurements of Aerosol and Cloud Vertical Distributions at Co-Located AERONET Sites

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Berkoff, Timothy A.; Spinhirne, James D.; Tsay, Si-Chee; Holben, Brent; Starr, David OC. (Technical Monitor)

    2002-01-01

    In the early 1990s, the first small, eye-safe, and autonomous lidar system was developed, the Micropulse Lidar (MPL). The MPL acquires signal profiles of backscattered laser light from aerosols and clouds. The signals are analyzed to yield multiple layer heights, optical depths of each layer, average extinction-to-backscatter ratios for each layer, and profiles of extinction in each layer. In 2000, several MPL sites were organized into a coordinated network, called MPL-Net, by the Cloud and Aerosol Lidar Group at NASA Goddard Space Flight Center (GSFC) using funding provided by the NASA Earth Observing System. tn addition to the funding provided by NASA EOS, the NASA CERES Ground Validation Group supplied four MPL systems to the project, and the NASA TOMS group contributed their MPL for work at GSFC. The Atmospheric Radiation Measurement Program (ARM) also agreed to make their data available to the MPL-Net project for processing. In addition to the initial NASA and ARM operated sites, several other independent research groups have also expressed interest in joining the network using their own instruments. Finally, a limited amount of EOS funding was set aside to participate in various field experiments each year. The NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) project also provides funds to deploy their MPL during ocean research cruises. All together, the MPL-Net project has participated in four major field experiments since 2000. Most MPL-Net sites and field experiment locations are also co-located with sunphotometers in the NASA Aerosol Robotic Network. (AERONET). Therefore, at these locations data is collected on both aerosol and cloud vertical structure as well as column optical depth and sky radiance. Real-time data products are now available from most MPL-Net sites. Our real-time products are generated at times of AERONET aerosol optical depth (AOD) measurements. The AERONET AOD is used as input to our

  3. CHARMS Combined Data Set

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ferrare, Richard; Thorsen, Tyler

    These multi-wavelength lidar data were collected during the Combined HSRL and Raman lidar Measurement Study (CHARMS) IOP that occurred during July through September 2015 at SGP. During CHARMS the University of Wisconsin HSRL was located at SGP and acquired aerosol backscatter profiles at 532 nm and 1064 nm and aerosol backscatter, extinction, and depolarization profiles at 532 nm. The HSRL aerosol profiles, when combined with the aerosol backscatter and extinction profiles (355 nm) collected by the SGP Raman lidar, provide a suite of three aerosol backscatter (355, 532, 1064 nm) and two aerosol extinction (355, 532 nm) profiles for usemore » in advanced aerosol microphysical retrievals. The data files in this PI product contain this suite of aerosol backscatter (355, 532, 1064), extinction (355, 532 nm), and depolarization (532 nm) profiles.« less

  4. Probing the 9.7 μm Interstellar Silicate Extinction Profile through the Spitzer/IRS Spectroscopy of OB Stars

    NASA Astrophysics Data System (ADS)

    Shao, Zhenzhen; Jiang, B. W.; Li, Aigen; Gao, Jian; Lv, Zhangpan; Yao, Jiawen

    2018-05-01

    The 9.7 μm interstellar spectral feature, arising from the Si-O stretch of amorphous silicate dust, is the strongest extinction feature in the infrared (IR). In principle, the spectral profile of this feature could allow one to diagnose the mineralogical composition of interstellar silicate material. However, observationally, the 9.7 μm interstellar silicate extinction profile is not well determined. Here we utilize the Spitzer/IRS spectra of five early-type (one O- and four B-type) stars and compare them with that of unreddened stars of the same spectral type to probe the interstellar extinction of silicate dust around 9.7 μm. We find that, while the silicate extinction profiles all peak at ˜ 9.7 μm, two stars exhibit a narrow feature of FWHM ˜ 2.0 μm and three stars display a broad feature of FWHM ˜ 3.0 μm. We also find that the width of the 9.7 μm extinction feature does not show any environmental dependence. With a FWHM of ˜ 2.2 μm, the mean 9.7 μm extinction profile, obtained by averaging over our five stars, closely resembles that of the prototypical diffuse interstellar medium along the lines of sight toward Cyg OB2 No. 12 and WR 98a. Finally, an analytical formula is presented to parameterize the interstellar extinction in the IR at 0.9 μm ≲ λ ≲ 15 μm.

  5. Development of Raman-Mie lidar system for aerosol and water vapor profiling

    NASA Astrophysics Data System (ADS)

    Deng, Qian; Wang, Zhenzhu; Xu, Jiwei; Tan, Min; Wu, Decheng; Xie, Chenbo; Liu, Dong; Wang, Yingjian

    2018-03-01

    Aerosol and water vapor are two important atmospheric parameters. The accurate quantification of diurnal variation of these parameters are very useful for environment assessment and climate change studies. A moveable, compact and unattended lidar system based on modular design is developed for aerosol extinction coefficients and water vapor mixing ratios measurements. In the southern suburbs of Beijing, the continuous observation was carried out by this lidar since the middle of the year of 2017. The lidar equipment is presented and the case study is also described in this paper. The observational results show that the lidar kept a very good status from the long-time continuous measurements which is suitable for networking especially in meteorological research field.

  6. Multi-aperture laser transmissometer system for long-path aerosol extinction rate measurement.

    PubMed

    Wu, Chensheng; Rzasa, John R; Ko, Jonathan; Paulson, Daniel A; Coffaro, Joseph; Spychalsky, Jonathan; Crabbs, Robert F; Davis, Christopher C

    2018-01-20

    We present the theory, design, simulation, and experimental evaluations of a new laser transmissometer system for aerosol extinction rate measurement over long paths. The transmitter emits an ON/OFF modulated Gaussian beam that does not require strict collimation. The receiver uses multiple point detectors to sample the sub-aperture irradiance of the arriving beam. The sparse detector arrangement makes our transmissometer system immune to turbulence-induced beam distortion and beam wander caused by the atmospheric channel. Turbulence effects often cause spatial discrepancies in beam propagation and lead to miscalculation of true power loss when using the conventional approach of measuring the total beam power directly with a large-aperture optical concentrator. Our transmissometer system, on the other hand, combines the readouts from distributed detectors to rule out turbulence-induced temporal power fluctuations. As a result, we show through both simulation and field experiments that our transmissometer system works accurately with turbulence strength Cn2 up to 10 -12   m -2/3 over a typical 1-km atmospheric channel. In application, our turbulence- and weather-resistant laser transmissometer system has significant advantages for the measurement and study of aerosol concentration, absorption, and scattering properties, which are crucial for directed energy systems, ground-level free-space optical communication systems, environmental monitoring, and weather forecasting.

  7. CATS Version 2 Aerosol Feature Detection and Applications for Data Assimilation

    NASA Technical Reports Server (NTRS)

    Nowottnick, Ed; Yorks, John; McGill, Matt; Scott, Stan; Palm, Stephen; Hlavka, Dennis; Hart, William; Selmer, Patrick; Kupchock, Andrew; Pauly, Rebecca

    2017-01-01

    Using GEOS-5, we are developing a 1D ENS approach for assimilating CATS near real time observations of total attenuated backscatter at 1064 nm: a) After performing a 1-ENS assimilation of a cloud-free profile, the GEOS-5 analysis closely followed observed total attenuated backscatter. b) Vertical localization length scales were varied for the well-mixed PBL and the free troposphere After assimilating a cloud free segment of a CATS granule, the fine detail of a dust event was obtained in the GEOS-5 analysis for both total attenuated backscatter and extinction. Future Work: a) Explore horizontal localization and test within a cloudy aerosol layer. b) Address noisy analysis increments in the free troposphere where both CATS and GEOS-5 aerosol loadings are low. c) Develop a technique to screen CATS ground return from profiles. d) "Dynamic" lidar ratio that will evolve in conjunction with simulated aerosol mixtures.

  8. Comparison of Aerosol Classification From Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, Sharon P.; Ferrare, Rich A.; Omar, Ali H.; Vaughan, Mark A.; Rogers, Raymond R.; Hostetler, Chris a.; Hair, Johnathan W.; Obland, Michael D.; Butler, Carolyn F.; Cook, Anthony L.; hide

    2012-01-01

    Knowledge of aerosol composition and vertical distribution is crucial for assessing the impact of aerosols on climate. In addition, aerosol classification is a key input to CALIOP aerosol retrievals, since CALIOP requires an inference of the lidar ratio in order to estimate the effects of aerosol extinction and backscattering. In contrast, the NASA airborne HSRL-1 directly measures both aerosol extinction and backscatter, and therefore the lidar ratio (extinction-to-backscatter ratio). Four aerosol intensive properties from HSRL-1 are combined to infer aerosol type. Aerosol classification results from HSRL-1 are used here to validate the CALIOP aerosol type inferences.

  9. Aerosol Attenuation in the 2-4 Micrometer Region

    DTIC Science & Technology

    1975-03-01

    Company Model 911ir dew point hydrometer. The lithium chloride sensors will be placed on the roof where the aerosol is sampled and at the entrance...Extinction Measurement il External View of 400 Meter White Cell 13 Primary Aerosol and Gas Handlinfe Systems 14 Calibration for Extinction...Massacusetts. Aerosol-laden air will be drawn into the experimental apparatus from a point 10 ft above the roof of the building. A continuoush

  10. A Chronology of Annual-Mean Effective Radii of Stratospheric Aerosols from Volcanic Eruptions During the Twentieth Century as Derived From Ground-based Spectral Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Strothers, Richard B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Stratospheric extinction can be derived from ground-based spectral photometric observations of the Sun and other stars (as well as from satellite and aircraft measurements, available since 1979), and is found to increase after large volcanic eruptions. This increased extinction shows a characteristic wavelength dependence that gives information about the chemical composition and the effective (or area weighted mean) radius of the particles responsible for it. Known to be tiny aerosols constituted of sulfuric acid in a water solution, the stratospheric particles at midlatitudes exhibit a remarkable uniformity of their column-averaged effective radii r(sub eff) in the first few months after the eruption. Considering the seven largest eruptions of the twentieth century, r(sub eff) at this phase of peak aerosol abundance is approx. 0.3 micrometers in all cases. A year later, r(sub eff) either has remained about the same size (almost certainly in the case of the Katmai eruption of 1912) or has increased to approx. 0.5 micrometers (definitely so for the Pinatubo eruption of 1991). The reasons for this divergence in aerosol growth are unknown.

  11. New in situ Aerosol Spectral Optical Measurements over 300-700 nm, Extinction and Total Absorption, Paired with Absorption from Water- and Methanol-soluble Aerosol Extracts

    NASA Astrophysics Data System (ADS)

    Jordan, C. E.; Stauffer, R. M.; Lamb, B.; Novak, M. G.; Mannino, A.; Hudgins, C.; Thornhill, K. L., II; Crosbie, E.; Winstead, E.; Anderson, B.; Martin, R.; Shook, M.; Ziemba, L. D.; Beyersdorf, A. J.; Corr, C.

    2017-12-01

    A new in situ spectral aerosol extinction instrument (custom built, SpEx) built to cover the 300-700 nm range at 1 nm spectral resolution and temporal resolution of 4 minutes was deployed on the top deck ( 10 m above the water surface) of the R/V Onnuri during the KORUS-OC research cruise around South Korea in spring 2016. This new instrument was one component of a suite of in situ aerosol optical measurements that included 3-visible-wavelength scattering (Airphoton IN101 Nephelometer, at 450, 532, & 632 nm) and absorption (Brechtel Tricolor Absorption Photometer Model 2901, at 467, 528, & 652 nm) with sub-minute temporal resolution; two sets of filters (Teflon and glass fiber, both collected over 3 hour daytime and 12 hour overnight intervals) to provide aerosol absorption spectra over the same wavelength range as SpEx. The glass fiber filters were placed in the center of an integrating sphere (Labsphere DRA-CA-30) attached to a dual beam spectrophotometer (Cary 100 Bio UV-Visible Spectrophotometer) to measure total aerosol absorption spectra via an established method used by the ocean color community to obtain absorption spectra from particles suspended in sea water. Adapting this methodology for atmospheric aerosol measurements provides a new avenue to obtain spectral total aerosol absorption, particularly useful for expanding in situ measurement capabilities into the UV range. The Teflon filters were cut in half with one half extracted in deionized water and the other half extracted in methanol. The solutions were filtered and injected into a liquid waveguide capillary cell (World Precision Instruments LWCC-3100, 100 cm pathlength) to measure the absorption spectra for each solution. In addition, the water extracts were measured via ion chromatography (Dionex ICS-3000 Ion Chromatography System) to obtain water-soluble inorganic ion concentrations, as well as via aerosol mass spectrometry (Aerodyne Research, Inc. HR-ToF High Resolution Aerosol Mass Spectrometer

  12. Aerosol Climate Time Series Evaluation In ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, T.; de Leeuw, G.; Pinnock, S.

    2015-12-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. By the end of 2015 full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which are also validated. The paper will summarize and discuss the results of major reprocessing and validation conducted in 2015. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension with successor instruments of the Sentinel family will be described and the complementarity of the different satellite aerosol products

  13. Seasonal variations of aerosol optical properties, vertical distribution and associated radiative effects in the Yangtze Delta Region of China

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Jianjun; Zheng, Youfei; Li, Zhanqing

    2012-02-09

    Four years of columnar aerosol particle optical properties (2006 to 2009) and one year database worth of aerosol particle vertical profile of 527 nm extinction coefficient (June 2008 to May 2009) are analyzed at Taihu in the central Yangtze Delta region in eastern China. Seasonal variations of aerosol optical properties, vertical distribution, and influence on shortwave radiation and heating rates were investigated. Multiyear variations of aerosol optical depths (AOD), Angstrom exponents, single scattering albedo (SSA) and asymmetry factor (ASY) are analyzed, together with the vertical profile of aerosol extinction. AOD is largest in summer and smallest in winter. SSAs exhibitmore » weak seasonal variation with the smallest values occurring during winter and the largest during summer. The vast majority of aerosol particles are below 2 km, and about 62%, 67%, 67% and 83% are confined to below 1 km in spring, summer, autumn and winter, respectively. Five-day back trajectory analyses show that the some aerosols aloft are traced back to northern/northwestern China, as far as Mongolia and Siberia, in spring, autumn and winter. The presence of dust aerosols were identified based on the linear depolarization measurements together with other information (i.e., back trajectory, precipitation, aerosol index). Dust strongly impacts the vertical particle distribution in spring and autumn, with much smaller effects in winter. The annual mean aerosol direct shortwave radiative forcing (efficiency) at the bottom, top and within the atmosphere are -34.8 {+-} 9.1 (-54.4 {+-} 5.3), -8.2 {+-} 4.8 (-13.1 {+-} 1.5) and 26.7 {+-} 9.4 (41.3 {+-} 4.6) W/m{sup 2} (Wm{sup -2} T{sup -1}), respectively. The mean reduction in direct and diffuse radiation reaching surface amount to 109.2 {+-} 49.4 and 66.8 {+-} 33.3 W/m{sup 2}, respectively. Aerosols significantly alter the vertical profile of solar heating, with great implications for atmospheric stability and dynamics within the lower

  14. Optical extinction dependence on wavelength and size distribution of airborne dust

    NASA Astrophysics Data System (ADS)

    Pangle, Garrett E.; Hook, D. A.; Long, Brandon J. N.; Philbrick, C. R.; Hallen, Hans D.

    2013-05-01

    The optical scattering from laser beams propagating through atmospheric aerosols has been shown to be very useful in describing air pollution aerosol properties. This research explores and extends that capability to particulate matter. The optical properties of Arizona Road Dust (ARD) samples are measured in a chamber that simulates the particle dispersal of dust aerosols in the atmospheric environment. Visible, near infrared, and long wave infrared lasers are used. Optical scattering measurements show the expected dependence of laser wavelength and particle size on the extinction of laser beams. The extinction at long wavelengths demonstrates reduced scattering, but chemical absorption of dust species must be considered. The extinction and depolarization of laser wavelengths interacting with several size cuts of ARD are examined. The measurements include studies of different size distributions, and their evolution over time is recorded by an Aerodynamic Particle Sizer. We analyze the size-dependent extinction and depolarization of ARD. We present a method of predicting extinction for an arbitrary ARD size distribution. These studies provide new insights for understanding the optical propagation of laser beams through airborne particulate matter.

  15. Forwardscattering corrections for optical extinction measurements in aerosol media. II - Polydispersions

    NASA Technical Reports Server (NTRS)

    Deepak, A.; Box, M. A.

    1978-01-01

    The paper presents a parametric study of the forwardscattering corrections for experimentally measured optical extinction coefficients in polydisperse particulate media, since some forward scattered light invariably enters, along with the direct beam, into the finite aperture of the detector. Forwardscattering corrections are computed by two methods: (1) using the exact Mie theory, and (2) the approximate Rayleigh diffraction formula for spherical particles. A parametric study of the dependence of the corrections on mode radii, real and imaginary parts of the complex refractive index, and half-angle of the detector's view cone has been carried out for three different size distribution functions of the modified gamma type. In addition, a study has been carried out to investigate the range of these parameters in which the approximate formulation is valid. The agreement is especially good for small-view cone angles and large particles, which improves significantly for slightly absorbing aerosol particles. Also discussed is the dependence of these corrections on the experimental design of the transmissometer systems.

  16. Vertical profile of aerosols in the Himalayan region using an ultralight aircraft platform

    NASA Astrophysics Data System (ADS)

    Singh, A.; Mahata, K.; Rupakheti, M.; Lawrence, M. G.; Junkermann, W.

    2017-12-01

    Indo-gangetic plain (IGP) and Himalayan foothills have large spatial and temporal heterogeneity in aerosols characteristics. Regional meteorology around 850-500 mb plays an important role in the transformation and transportation of aerosols from west Asia to IGP, into Himalayan foothill, as well to high-altitude region of the Himalayas. In order to quantify the vertical and horizontal variation of aerosol properties in the Himalayan , an airborne campaign was carried out in the Pokhara Valley/Nepal (83°50'-84°10' E, 25°7'-28°15' N, 815 masl ) in two phases: test flights during May 2016 and an intensive airborne sampling flight in December-January 2017. This paper provides an overview of airborne measurement campaign from the first phase of measurements in May 2016. A two-seater microlight aircraft (IKARUS C 42) was used as the aerial platform. This was deemed the feasible option in Nepal for an aerial campaign; technical specification of the aircraft include an approximately 6 hrs of flying time, short-take off run, > 100 kgs of payload, suitable for spiral upward and downward profiling. The instrument package consist of GRIMM 1.108 for particle size distribution from 0.3 to 20 um at 6 seconds time resolution, and TSI CPC 3375 for total ultrafine particle (UFP) concentration at 1 s. The package also includes a Magee Scientific Aethalometer (AE42) for aerosol absorption at seven different wavelengths. Meteorological parameters include temperature and dew point at a sampling rate of 1 Hz or higher. The paper provides a snapshot of observed vertical profile (from 800 to 4500masl) of aerosols size, number and black carbon over one of populated mountain valley in Nepal during the pre-monsoon season. During the airborne measurement, local fires- mostly agriculture burn were observed, however no large scale forest fire was captured. Sharp morning and afternoon gradients were observed in the vertical profile for aerosol number and size, mostly dominated by <400 nm. The

  17. CART Raman Lidar Aerosol and Water Vapor Measurements in the Vicinity of Clouds

    NASA Technical Reports Server (NTRS)

    Clayton, Marian B.; Ferrare, Richard A.; Turner, David; Newsom, Rob; Sivaraman, Chitra

    2008-01-01

    Aerosol and water vapor profiles acquired by the Raman lidar instrument located at the Climate Research Facility (CRF) at Southern Great Plains (SGP) provide data necessary to investigate the atmospheric variability in the vicinity of clouds near the top of the planetary boundary layer (PBL). Recent CARL upgrades and modifications to the routine processing algorithms afforded the necessarily high temporal and vertical data resolutions for these investigations. CARL measurements are used to investigate the behavior of aerosol backscattering and extinction and their correlation with water vapor and relative humidity.

  18. The PM2.5 threshold for aerosol extinction in the Beijing megacity

    NASA Astrophysics Data System (ADS)

    Kong, Lingbin; Xin, Jinyuan; Liu, Zirui; Zhang, Kequan; Tang, Guiqian; Zhang, Wenyu; Wang, Yuesi

    2017-10-01

    Particulate pollution has remained at a high level in the megacity of Beijing in the past decade. The PM2.5, PM10, aerosol optical depth (AOD), Angstrom exponent(α), and PM2.5/PM10 ratio (the proportion of PM2.5 in PM10) in Beijing were 70±6 μg m-3, 128±6 μg m-3, 0.57 ± 0.05, 1.10 ± 0.08, 45 ± 4%, respectively, from 2005 to 2014. The annual means of PM concentration, AOD, α, and PM2.5/PM10 ratio decreased slightly during this decade, meanwhile PM concentration increased in the winter. Furthermore, we found there were thresholds of PM2.5 concentration for aerosol extinction. When the PM concentration was lower than a certain threshold, AOD decreased quickly with the decline of PM concentration. To make the improvement of the particle pollution more noticeable, the PM concentration should be controlled under the threshold. The annual averaged threshold is 63 μg m-3, and the threshold values reached the maximum of 74 μg m-3 in spring, ranged from 54 to 56 μg m-3 in the three other seasons. The threshold values ranged from 55 to 77 μg m-3 under other relevant factors, including air masses directions and relative humidity.

  19. LIVAS: a 3-D multi-wavelength aerosol/cloud database based on CALIPSO and EARLINET

    NASA Astrophysics Data System (ADS)

    Amiridis, V.; Marinou, E.; Tsekeri, A.; Wandinger, U.; Schwarz, A.; Giannakaki, E.; Mamouri, R.; Kokkalis, P.; Binietoglou, I.; Solomos, S.; Herekakis, T.; Kazadzis, S.; Gerasopoulos, E.; Proestakis, E.; Kottas, M.; Balis, D.; Papayannis, A.; Kontoes, C.; Kourtidis, K.; Papagiannopoulos, N.; Mona, L.; Pappalardo, G.; Le Rille, O.; Ansmann, A.

    2015-07-01

    We present LIVAS (LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies), a 3-D multi-wavelength global aerosol and cloud optical database, optimized to be used for future space-based lidar end-to-end simulations of realistic atmospheric scenarios as well as retrieval algorithm testing activities. The LIVAS database provides averaged profiles of aerosol optical properties for the potential spaceborne laser operating wavelengths of 355, 532, 1064, 1570 and 2050 nm and of cloud optical properties at the wavelength of 532 nm. The global database is based on CALIPSO observations at 532 and 1064 nm and on aerosol-type-dependent backscatter- and extinction-related Ångström exponents, derived from EARLINET (European Aerosol Research Lidar Network) ground-based measurements for the UV and scattering calculations for the IR wavelengths, using a combination of input data from AERONET, suitable aerosol models and recent literature. The required spectral conversions are calculated for each of the CALIPSO aerosol types and are applied to CALIPSO backscatter and extinction data corresponding to the aerosol type retrieved by the CALIPSO aerosol classification scheme. A cloud optical database based on CALIPSO measurements at 532 nm is also provided, neglecting wavelength conversion due to approximately neutral scattering behavior of clouds along the spectral range of LIVAS. Averages of particle linear depolarization ratio profiles at 532 nm are provided as well. Finally, vertical distributions for a set of selected scenes of specific atmospheric phenomena (e.g., dust outbreaks, volcanic eruptions, wild fires, polar stratospheric clouds) are analyzed and spectrally converted so as to be used as case studies for spaceborne lidar performance assessments. The final global data set includes 4-year (1 January 2008-31 December 2011) time-averaged CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) data on a uniform grid of 1

  20. Earth Science With the Stratospheric Aerosol and Gas Experiment III (SAGE III) on the International Space Station

    NASA Technical Reports Server (NTRS)

    Zawodny, Joe; Vernier, Jean-Paul; Thomason, Larry; Roell, Marilee; Pitts, Mike; Moore, Randy; Hill, Charles; Flittner, David; Damadeo, Rob; Cisewski, Mike

    2015-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) III is the fourth generation of solar occultation instruments operated by NASA, the first coming under a different acronym, to investigate the Earth's upper atmosphere. Three flight-ready SAGE III instruments were built by Ball Aerospace in the late 1990s, with one launched aboard the former Russian Aviation and Space Agency (now known as Roskosmos) Meteor-3M platform on 10 December 2001 (continuing until the platform lost power in 2006). Another of the original instruments was manifested for the ISS in the 2004 time frame, but was delayed because of budgetary considerations. Fortunately, that SAGE III/ISS mission was restarted in 2009 with a major focus upon filling an anticipated gap in ozone and aerosol observation in the second half of this decade. Here we discuss the mission architecture, its implementation, and data that will be produced by SAGE III/ISS, including their expected accuracy and coverage. The 52-degree inclined orbit of the ISS is well-suited for solar occultation and provides near-global observations on a monthly basis with excellent coverage of low and mid-latitudes. This is similar to that of the SAGE II mission (1985-2005), whose data set has served the international atmospheric science community as a standard for stratospheric ozone and aerosol measurements. The nominal science products include vertical profiles of trace gases, such as ozone, nitrogen dioxide and water vapor, along with multi-wavelength aerosol extinction. Though in the visible portion of the spectrum the brightness of the Sun is one million times that of the full Moon, the SAGE III instrument is designed to cover this large dynamic range and also perform lunar occultations on a routine basis to augment the solar products. The standard lunar products were demonstrated during the SAGE III/M3M mission and include ozone, nitrogen dioxide & nitrogen trioxide. The operational flexibility of the SAGE III spectrometer accomplishes

  1. Lidar method of measurement of atmospheric extinction and ozone profiles

    NASA Technical Reports Server (NTRS)

    Cooney, J. A.

    1986-01-01

    A description of a method of measurement of atmospheric extinction and of ozone profiles by use of the backscatter signal from a monostatic lidar is given. The central feature of the procedure involves a measurement of the ratio of the Raman backscatter returns of both the oxygen and nitrogen atmospheric content. Because the ratio of the number density of both species is known to high accuracy, the measurement itself becomes a measure of the ratio of two transmissions to altitude along with a ratio of the two system constants. The calibration measurement for determining the value of the ratio of the two system constants or electro-optical conversion constants is accomplished by a lidar measurement of identical atmospheric targets while at the same time interchanging the two optical filters in the two optical channels of the receiver. More details of the procedure are discussed. Factoring this calibrated value into the measured O2/N2 profile ratio provides a measured value of the ratio of the two transmissions. Or equivalently, it provides a measurement of the difference of the two extinction coefficients at the O2 and N2 Raman wavelengths as a function of the height.

  2. Extinction of CO2 Laser Radiation Under Adverse Weather Conditions

    DTIC Science & Technology

    1982-06-01

    System Design 60 a, Gaussian Optics 60 b, Laser Transmissometer 61 4. Measurement Errors 68 VI DISCUSSION OF RESULTS 69 1, Introduction...water soluble aerosols (a 1 106 AFWAL-TR-81 -.1280 TABLE 17 EXTINCTION OF CO2 LASER LINES FOR A CONSTANI RAIN RATE OF 1.82 mm/HR, 22 APRIL, 1935 HOURS...number) Laser Propagation Rain Laser Extinction CO2 Lasers Adverse Weather Aerosol s - 20 RACT (Continue on reverse side If necessary

  3. Modeling of Aerosol Vertical Profiles Using GIS and Remote Sensing

    PubMed Central

    Wong, Man Sing; Nichol, Janet E.; Lee, Kwon Ho

    2009-01-01

    The use of Geographic Information Systems (GIS) and Remote Sensing (RS) by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future. PMID:22408531

  4. Modeling of Aerosol Vertical Profiles Using GIS and Remote Sensing.

    PubMed

    Wong, Man Sing; Nichol, Janet E; Lee, Kwon Ho

    2009-01-01

    The use of Geographic Information Systems (GIS) and Remote Sensing (RS) by climatologists, environmentalists and urban planners for three dimensional modeling and visualization of the landscape is well established. However no previous study has implemented these techniques for 3D modeling of atmospheric aerosols because air quality data is traditionally measured at ground points, or from satellite images, with no vertical dimension. This study presents a prototype for modeling and visualizing aerosol vertical profiles over a 3D urban landscape in Hong Kong. The method uses a newly developed technique for the derivation of aerosol vertical profiles from AERONET sunphotometer measurements and surface visibility data, and links these to a 3D urban model. This permits automated modeling and visualization of aerosol concentrations at different atmospheric levels over the urban landscape in near-real time. Since the GIS platform permits presentation of the aerosol vertical distribution in 3D, it can be related to the built environment of the city. Examples are given of the applications of the model, including diagnosis of the relative contribution of vehicle emissions to pollution levels in the city, based on increased near-surface concentrations around weekday rush-hour times. The ability to model changes in air quality and visibility from ground level to the top of tall buildings is also demonstrated, and this has implications for energy use and environmental policies for the tall mega-cities of the future.

  5. Atmospheric aerosol profiling with a bistatic imaging lidar system.

    PubMed

    Barnes, John E; Sharma, N C Parikh; Kaplan, Trevor B

    2007-05-20

    Atmospheric aerosols have been profiled using a simple, imaging, bistatic lidar system. A vertical laser beam is imaged onto a charge-coupled-device camera from the ground to the zenith with a wide-angle lens (CLidar). The altitudes are derived geometrically from the position of the camera and laser with submeter resolution near the ground. The system requires no overlap correction needed in monostatic lidar systems and needs a much smaller dynamic range. Nighttime measurements of both molecular and aerosol scattering were made at Mauna Loa Observatory. The CLidar aerosol total scatter compares very well with a nephelometer measuring at 10 m above the ground. The results build on earlier work that compared purely molecular scattered light to theory, and detail instrument improvements.

  6. Remote sensing and in-situ measurements of tropospheric aerosol, a PAMARCMiP case study

    NASA Astrophysics Data System (ADS)

    Hoffmann, Anne; Osterloh, Lukas; Stone, Robert; Lampert, Astrid; Ritter, Christoph; Stock, Maria; Tunved, Peter; Hennig, Tabea; Böckmann, Christine; Li, Shao-Meng; Eleftheriadis, Kostas; Maturilli, Marion; Orgis, Thomas; Herber, Andreas; Neuber, Roland; Dethloff, Klaus

    2012-06-01

    In this work, a closure experiment for tropospheric aerosol is presented. Aerosol size distributions and single scattering albedo from remote sensing data are compared to those measured in-situ. An aerosol pollution event on 4 April 2009 was observed by ground based and airborne lidar and photometer in and around Ny-Ålesund, Spitsbergen, as well as by DMPS, nephelometer and particle soot absorption photometer at the nearby Zeppelin Mountain Research Station. The presented measurements were conducted in an area of 40 × 20 km around Ny-Ålesund as part of the 2009 Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project (PAMARCMiP). Aerosol mainly in the accumulation mode was found in the lower troposphere, however, enhanced backscattering was observed up to the tropopause altitude. A comparison of meteorological data available at different locations reveals a stable multi-layer-structure of the lower troposphere. It is followed by the retrieval of optical and microphysical aerosol parameters. Extinction values have been derived using two different methods, and it was found that extinction (especially in the UV) derived from Raman lidar data significantly surpasses the extinction derived from photometer AOD profiles. Airborne lidar data shows volume depolarization values to be less than 2.5% between 500 m and 2.5 km altitude, hence, particles in this range can be assumed to be of spherical shape. In-situ particle number concentrations measured at the Zeppelin Mountain Research Station at 474 m altitude peak at about 0.18 μm diameter, which was also found for the microphysical inversion calculations performed at 850 m and 1500 m altitude. Number concentrations depend on the assumed extinction values, and slightly decrease with altitude as well as the effective particle diameter. A low imaginary part in the derived refractive index suggests weakly absorbing aerosols, which is confirmed by low black carbon concentrations, measured at the

  7. Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements: Evaluation of Aerosol Measurements from SAGE II, HALOE, and Balloonborne Optical Particle Counters

    NASA Technical Reports Server (NTRS)

    Hervig, Mark; Deshler, Terry; Moddrea, G. (Technical Monitor)

    2002-01-01

    Stratospheric aerosol measurements from the University of Wyoming balloonborne optical particle counters (OPCs), the Stratospheric Aerosol and Gas Experiment (SAGE) II, and the Halogen Occultation Experiment (HALOE) were compared in the period 1982-2000, when measurements were available. The OPCs measure aerosol size distributions, and HALOE multiwavelength (2.45-5.26 micrometers) extinction measurements can be used to retrieve aerosol size distributions. Aerosol extinctions at the SAGE II wavelengths (0.386-1.02 micrometers) were computed from these size distributions and compared to SAGE II measurements. In addition, surface areas derived from all three experiments were compared. While the overall impression from these results is encouraging, the agreement can change with latitude, altitude, time, and parameter. In the broadest sense, these comparisons fall into two categories: high aerosol loading (volcanic periods) and low aerosol loading (background periods and altitudes above 25 km). When the aerosol amount was low, SAGE II and HALOE extinctions were higher than the OPC estimates, while the SAGE II surface areas were lower than HALOE and the OPCS. Under high loading conditions all three instruments mutually agree to within 50%.

  8. Retrieval of aerosol optical and micro-physical properties with 2D-MAX-DOAS

    NASA Astrophysics Data System (ADS)

    Ortega, Ivan; Coburn, Sean; Hostetler, Chris; Ferrare, Rich; Hair, Johnathan; Kassianov, Evgueni; Barnard, James; Berg, Larry; Schmid, Beat; Tomlinson, Jason; Hodges, Gary; Lantz, Kathy; Wagner, Thomas; Volkamer, Rainer

    2015-04-01

    Recent retrievals of 2 dimensional (2D) Multi-AXis Differential Optical Absorption Spectroscopy (2D-MAX-DOAS) have highlighted its importance in order to infer diurnal horizontal in-homogeneities around the measurement site. In this work, we expand the capabilities of 2D measurements in order to estimate simultaneously aerosol optical and micro-physical properties. Specifically, we present a retrieval method to obtain: (1) aerosol optical thickness (AOT) in the boundary layer (BL) and free troposphere (FT) and (2) the effective complex refractive index and the effective radius of the aerosol column size distribution. The retrieval method to obtain AOT is based on an iterative comparison of measured normalized radiances, oxygen collision pair (O4), and absolute Raman Scattering Probability (RSP) with the forward model calculations derived with the radiative transfer model McArtim based on defined aerosol extinction profiles. Once the aerosol load is determined we use multiple scattering phase functions and single scattering albedo (SSA) obtained with Mie calculations which then constrain the RTM to forward model solar almucantar normalized radiances. The simulated almucantar normalized radiances are then compared to the measured normalized radiances. The best-fit, determined by minimizing the root mean square, retrieves the complex refractive index, and effective radius. We apply the retrieval approach described above to measurements carried out during the 2012 intensive operation period of the Two Column Aerosol Project (TCAP) held on Cape Cod, MA, USA. Results are presented for two ideal case studies with both large and small aerosol loading and similar air mass outflow from the northeast coast of the US over the West Atlantic Ocean. The aerosol optical properties are compared with several independent instruments, including the NASA Langley airborne High Spectral Resolution Lidar (HSRL-2) for highly resolved extinction profiles during the overpasses, and with the

  9. Seasonal aerosol characteristics in the Amazon rain forest

    NASA Astrophysics Data System (ADS)

    Baars, H.; Althausen, D.; Ansmann, A.; Engelmann, R.; Heese, B.; Müller, D.; Pauliquevis, T.; Souza, R.; Artaxo, P.

    2012-04-01

    For the first time in Amazonia, continuous measurements of the vertical aerosol structure were carried out in the framework of EUCAARI (European Integrated Project on Aerosol, Cloud, Climate, Air Quality Interactions) and AMAZE-08 (Amazonian Aerosol Characterization Experiment). The observations were performed 60 km north of Manaus, Brazil (at 2° 35.5' S and 60° 2.3' W) in the central northern part of the Amazon rain forest from January to November 2008 with the automated multi-wavelength-Raman-polarization-lidar PollyXT. With this instrument, vertical profiles of the particle backscatter coefficient at 355, 532, and 1064 nm, of the particle extinction coefficient at 355 and 532 nm, and of the particle linear depolarization ratio at 355 nm can be determined. During the 10-months observational period, measurements were performed on 211 days resulting in more than 2500 hours of tropospheric aerosol and cloud profile observations. The analysis of the long-term data set revealed strong differences in the aerosol characteristics between the wet and the dry season. In the wet season, very clean atmospheric conditions occurred in ca. 50% of all observation cases. During these clean conditions, the aerosol optical depth (AOD) at 532 nm was less than 0.05 and the aerosol was trapped in the lowermost 2 km of the troposphere. However, also intrusions of Saharan dust and African biomass-burning aerosol (BBA) - characterized by a significantly increased AOD and particle depolarization ratio - were observed in about one third (32%) of all lidar observations. These African aerosol plumes extended usually from the surface up to about 3.5 km agl. During the dry season, BBA from fires on the South American continent was the dominant aerosol species. The mean AOD of the dry season was found to be a factor of 3 higher than the mean AOD of the wet season (0.26 compared to 0.08 at 532 nm). This is due to the high BBA concentration in the atmosphere. Maximum AOD values were less than 0

  10. Three-beam aerosol backscatter correlation lidar for wind profiling

    NASA Astrophysics Data System (ADS)

    Prasad, Narasimha S.; Radhakrishnan Mylapore, Anand

    2017-03-01

    The development of a three-beam aerosol backscatter correlation (ABC) light detection and ranging (lidar) to measure wind characteristics for wake vortex and plume tracking applications is discussed. This is a direct detection elastic lidar that uses three laser transceivers, operating at 1030-nm wavelength with ˜10-kHz pulse repetition frequency and nanosec class pulse widths, to directly obtain three components of wind velocities. By tracking the motion of aerosol structures along and between three near-parallel laser beams, three-component wind speed profiles along the field-of-view of laser beams are obtained. With three 8-in. transceiver modules, placed in a near-parallel configuration on a two-axis pan-tilt scanner, the lidar measures wind speeds up to 2 km away. Optical flow algorithms have been adapted to obtain the movement of aerosol structures between the beams. Aerosol density fluctuations are cross-correlated between successive scans to obtain the displacements of the aerosol features along the three axes. Using the range resolved elastic backscatter data from each laser beam, which is scanned over the volume of interest, a three-dimensional map of aerosol density can be generated in a short time span. The performance of the ABC wind lidar prototype, validated using sonic anemometer measurements, is discussed.

  11. Aerosol Climate Time Series in ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon

    2016-04-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve algorithms for the retrieval of aerosol information from European sensors. Meanwhile, full mission time series of 2 GCOS-required aerosol parameters are completely validated and released: Aerosol Optical Depth (AOD) from dual view ATSR-2 / AATSR radiometers (3 algorithms, 1995 - 2012), and stratospheric extinction profiles from star occultation GOMOS spectrometer (2002 - 2012). Additionally, a 35-year multi-sensor time series of the qualitative Absorbing Aerosol Index (AAI) together with sensitivity information and an AAI model simulator is available. Complementary aerosol properties requested by GCOS are in a "round robin" phase, where various algorithms are inter-compared: fine mode AOD, mineral dust AOD (from the thermal IASI spectrometer, but also from ATSR instruments and the POLDER sensor), absorption information and aerosol layer height. As a quasi-reference for validation in few selected regions with sparse ground-based observations the multi-pixel GRASP algorithm for the POLDER instrument is used. Validation of first dataset versions (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account for a reprocessing. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. For the three ATSR algorithms the use of an ensemble method was tested. The paper will summarize and discuss the status of dataset reprocessing and validation. The focus will be on the ATSR, GOMOS and IASI datasets. Pixel level uncertainties validation will be summarized and discussed including unknown components and their potential usefulness and limitations. Opportunities for time series extension

  12. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  13. Current Research in Lidar Technology Used for the Remote Sensing of Atmospheric Aerosols

    PubMed Central

    Comerón, Adolfo; Muñoz-Porcar, Constantino; Rocadenbosch, Francesc; Rodríguez-Gómez, Alejandro; Sicard, Michaël

    2017-01-01

    Lidars are active optical remote sensing instruments with unique capabilities for atmospheric sounding. A manifold of atmospheric variables can be profiled using different types of lidar: concentration of species, wind speed, temperature, etc. Among them, measurement of the properties of aerosol particles, whose influence in many atmospheric processes is important but is still poorly stated, stands as one of the main fields of application of current lidar systems. This paper presents a review on fundamentals, technology, methodologies and state-of-the art of the lidar systems used to obtain aerosol information. Retrieval of structural (aerosol layers profiling), optical (backscatter and extinction coefficients) and microphysical (size, shape and type) properties requires however different levels of instrumental complexity; this general outlook is structured following a classification that attends these criteria. Thus, elastic systems (detection only of emitted frequencies), Raman systems (detection also of Raman frequency-shifted spectral lines), high spectral resolution lidars, systems with depolarization measurement capabilities and multi-wavelength instruments are described, and the fundamentals in which the retrieval of aerosol parameters is based is in each case detailed. PMID:28632170

  14. Intercomparison of aerosol optical parameters from WALI and R-MAN510 aerosol Raman lidars in the framework of HyMeX campaign

    NASA Astrophysics Data System (ADS)

    Boytard, Mai-Lan; Royer, Philippe; Chazette, Patrick; Shang, Xiaoxia; Marnas, Fabien; Totems, Julien; Bizard, Anthony; Bennai, Baya; Sauvage, Laurent

    2013-04-01

    The HyMeX program (Hydrological cycle in Mediterranean eXperiment) aims at improving our understanding of hydrological cycle in the Mediterranen and at a better quantification and forecast of high-impact weather events in numerical weather prediction models. The first Special Observation Period (SOP1) took place in September/October 2012. During this period two aerosol Raman lidars have been deployed at Menorca Island (Spain) : one Water-vapor and Aerosol Raman LIdar (WALI) operated by LSCE/CEA (Laboratoire des Sciences du Climat et de l'Environnement/Commissariat à l'Energie Atomique) and one aerosol Raman and dual-polarization lidar (R-Man510) developed and commercialized by LEOSPHERE company. Both lidars have been continuously running during the campaign and have provided information on aerosol and cloud optical properties under various atmospheric conditions (maritime background aerosols, dust events, cirrus clouds...). We will present here the results of intercomparisons between R-Man510, and WALI aerosol lidar systems and collocated sunphotometer measurements. Limitations and uncertainties on the retrieval of extinction coefficients, depolarization ratio, aerosol optical depths and detection of atmospheric structures (planetary boundary layer height, aerosol/cloud layers) will be discussed according atmospheric conditions. The results will also be compared with theoretical uncertainty assessed with direct/inverse model of lidar profiles.

  15. Microphysical and optical properties of aerosol particles in urban zone during ESCOMPTE

    NASA Astrophysics Data System (ADS)

    Mallet, M.; Roger, J. C.; Despiau, S.; Dubovik, O.; Putaud, J. P.

    2003-10-01

    Microphysical and optical properties of the main aerosol species on a peri-urban site have been investigated during the ESCOMPTE experiment. Ammonium sulfate (AS), nitrate (N), black carbon (BC), particulate organic matter (POM), sea salt (SS) and mineral aerosol (D) size distributions have been used, associated with their refractive index, to compute, from the Mie theory, the key radiative aerosol properties as the extinction coefficient Kext, the mass extinction efficiencies σext, the single scattering albedo ω0 and the asymmetry parameter g at the wavelength of 550 nm. Optical computations show that 90% of the light extinction is due to anthropogenic aerosol and only 10% is due to natural aerosol (SS and D). 44±6% of the extinction is due to (AS) and 40±6% to carbonaceous particles (20±4% to BC and 21±4% to POM). Nitrate aerosol has a weak contribution of 5±2%. Computations of the mass extinction efficiencies σext, single scattering albedo ω0 and asymmetry parameter g indicate that the optical properties of the anthropogenic aerosol are often quite different from those yet published and generally used in global models. For example, the (AS) mean specific mass extinction presents a large difference with the value classically adopted at low relative humidity ( h<60%) (2.6±0.5 instead of 6 m 2 g -1 at 550 nm). The optical properties of the total aerosol layer, including all the aerosol species, indicate a mean observed single-scattering albedo ω0=0.85±0.05, leading to an important absorption of the solar radiation and an asymmetry parameter g=0.59±0.05 which are in a reasonably good agreements with the AERONET retrieval of ω0 (=0.86±0.05) and g (=0.64±0.05) at this wavelength.

  16. Light extinction by aerosols during summer air pollution

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Fraser, R. S.

    1983-01-01

    In order to utilize satellite measurements of optical thickness over land for estimating aerosol properties during air pollution episodes, the optical thickness was measured from the surface and investigated. Aerosol optical thicknesses have been derived from solar transmission measurements in eight spectral bands within the band lambda 440-870 nm during the summers of 1980 and 1981 near Washington, DC. The optical thicknesses for the eight bands are strongly correlated. It was found that first eigenvalue of the covariance matrix of all observations accounts for 99 percent of the trace of the matrix. Since the measured aerosol optical thickness was closely proportional to the wavelength raised to a power, the aerosol size distribution derived from it is proportional to the diameter (d) raised to a power for the range of diameters between 0.1 to 1.0 micron. This power is insensitive to the total optical thickness. Changes in the aerosol optical thickness depend on several aerosol parameters, but it is difficult to identify the dominant one. The effects of relative humidity and accumulation mode concentration on the optical thickness are analyzed theoretically, and compared with the measurements.

  17. Shortwave Radiative Fluxes, Solar-Beam Transmissions, and Aerosol Properties: TARFOX and ACE-2 Find More Absorption from Flux Radiometry than from Other Measurements

    NASA Technical Reports Server (NTRS)

    Russell, Philip B.; Redemann, J.; Schmid, B.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    The Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2) made simultaneous measurements of shortwave radiative fluxes, solar-beam transmissions, and the aerosols affecting those fluxes and transmissions. Besides the measured fluxes and transmissions, other obtained properties include aerosol scattering and absorption measured in situ at the surface and aloft; aerosol single scattering albedo retrieved from skylight radiances; and aerosol complex refractive index derived by combining profiles of backscatter, extinction, and size distribution. These measurements of North Atlantic boundary layer aerosols impacted by anthropogenic pollution revealed the following characteristic results: (1) Better agreement among different types of remote measurements of aerosols (e.g., optical depth, extinction, and backscattering from sunphotometers, satellites, and lidars) than between remote and in situ measurements; 2) More extinction derived from transmission measurements than from in situ measurements; (3) Larger aerosol absorption inferred from flux radiometry than from other measurements. When the measured relationships between downwelling flux and optical depth (or beam transmission) are used to derive best-fit single scattering albedos for the polluted boundary layer aerosol, both TARFOX and ACE-2 yield midvisible values of 0.90 +/- 0.04. The other techniques give larger single scattering albedos (i.e. less absorption) for the polluted boundary layer, with a typical result of 0.95 +/- 0.04. Although the flux-based results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., unknown gas absorption). Current uncertainties in aerosol single scattering albedo are large in terms of climate effects. They also have an important influence on aerosol optical depths retrieved from satellite radiances

  18. Effect of atmospheric extinction on laser rangefinder performance at 1.54 and 0.6 microns

    NASA Technical Reports Server (NTRS)

    Hutt, D. L.; Theriault, J.-M.; Larochelle, V.; Bonnier, D.

    1992-01-01

    Extinction of laser rangefinder (LRF) pulses by the atmosphere depends on the wavelength, weather conditions, and aerosol concentration along the optical path. In the IR, extinction is due to absorption by molecular constituents and scattering and absorption by aerosols. The total atmospheric extinction alpha(lambda) is the sum of the molecular and aerosol contributions, alpha(sub m)(lambda)and Alpha(sub a)(lambda). We present simple expressions for alpha(sub m)(lambda) and alpha(sub a)(lambda) for two LRF sources: Er:glass and CO2 which operate at 1.54 and 10.6 microns, respectively. The expressions are based on accepted models of atmospheric aerosols and molecular extinction and give an estimate of alpha(lambda) as a function of standard meteorological parameters, assuming horizontal beam propagation. Signal-to-noise ratios of LRF returns, measured from a reference target under different weather conditions are compared to predictions based on the estimate of alpha(lambda).

  19. Inversion of scattered radiance horizon profiles for gaseous concentrations and aerosol parameters

    NASA Technical Reports Server (NTRS)

    Malchow, H. L.; Whitney, C. K.

    1977-01-01

    Techniques have been developed and used to invert limb scan measurements for vertical profiles of atmospheric state parameters. The parameters which can be found are concentrations of Rayleigh scatters, ozone, NO2, and aerosols, and aerosol physical properties including a Junge-size distribution parameter and real and imaginary parts of the index of refraction.

  20. Series cell light extinction monitor

    DOEpatents

    Novick, Vincent J.

    1990-01-01

    A method and apparatus for using the light extinction measurements from two or more light cells positioned along a gasflow chamber in which the gas volumetric rate is known to determine particle number concentration and mass concentration of an aerosol independent of extinction coefficient and to determine estimates for particle size and mass concentrations. The invention is independent of particle size. This invention has application to measurements made during a severe nuclear reactor fuel damage test.

  1. Helicopter-borne observations of the continental background aerosol in combination with remote sensing and ground-based measurements

    NASA Astrophysics Data System (ADS)

    Düsing, Sebastian; Wehner, Birgit; Seifert, Patric; Ansmann, Albert; Baars, Holger; Ditas, Florian; Henning, Silvia; Ma, Nan; Poulain, Laurent; Siebert, Holger; Wiedensohler, Alfred; Macke, Andreas

    2018-01-01

    This paper examines the representativeness of ground-based in situ measurements for the planetary boundary layer (PBL) and conducts a closure study between airborne in situ and ground-based lidar measurements up to an altitude of 2300 m. The related measurements were carried out in a field campaign within the framework of the High-Definition Clouds and Precipitation for Advancing Climate Prediction (HD(CP)2) Observational Prototype Experiment (HOPE) in September 2013 in a rural background area of central Europe.The helicopter-borne probe ACTOS (Airborne Cloud and Turbulence Observation System) provided measurements of the aerosol particle number size distribution (PNSD), the aerosol particle number concentration (PNC), the number concentration of cloud condensation nuclei (CCN-NC), and meteorological atmospheric parameters (e.g., temperature and relative humidity). These measurements were supported by the ground-based 3+2 wavelength polarization lidar system PollyXT, which provided profiles of the particle backscatter coefficient (σbsc) for three wavelengths (355, 532, and 1064 nm). Particle extinction coefficient (σext) profiles were obtained by using a fixed backscatter-to-extinction ratio (also lidar ratio, LR). A new approach was used to determine profiles of CCN-NC for continental aerosol. The results of this new approach were consistent with the airborne in situ measurements within the uncertainties.In terms of representativeness, the PNSD measurements on the ground showed a good agreement with the measurements provided with ACTOS for lower altitudes. The ground-based measurements of PNC and CCN-NC are representative of the PBL when the PBL is well mixed. Locally isolated new particle formation events on the ground or at the top of the PBL led to vertical variability in the cases presented here and ground-based measurements are not entirely representative of the PBL. Based on Mie theory (Mie, 1908), optical aerosol properties under ambient conditions for

  2. On relationship between aerosols and PM2.5

    NASA Astrophysics Data System (ADS)

    Sano, Itaru; Mukai, Sonoyo; Nakata, Makiko

    2015-04-01

    Since aerosol optical thickness (AOT) is a key parameter of aerosols and description of the Earth's radiation budget, it is widely measured from ground sun photometer network NASA/AERONET [Holben et al., 1998] and from satellite. Fine and surface level aerosol particle called PM2.5, whose diameter is 2.5 μ m or less, is a well-known parameter for understanding polluted level of air. Smirnov et al. reported a good agreement between ground based AERONET AOT (870 nm) and dust concentrations at Barbados [Smirnov et al., 2000]. Wang and Christopher founded a good correlation between satellite based MODIS AOT product and PM2.5 in Alabama area [Wang and 2003]. Long range transported dusts, particularly Asian dust events, are easy to change the vertical profile of aerosol extinction. The vertical profile is important to estimate PM information because both AOT information measured from ground or satellite are integrated value of aerosol extinction from ground to space, i.e. columnar AOT. Thus, we have also proposed correlations between ground level PM2.5 and AERONET AOT (670 nm) in two cases of ordinary air condition and dusty days [Sano et al., 2010]. In this work, we investigate the relationship between PM2.5 and AERONET AOT considering LIDAR measurements. Note that all of instruments are set up at the roof of the University building (50 m) and collocated in 10 m area. Surface-level AOT is derived from AERONET AOT multiplied by an averaged vertical aerosol extinction given by LIDAR. Note that the definition of surface-level AOT in this work is assumed as AOT up to 500 m height. Introduction of surface-level AOT enables to avoid the contamination of dusty aerosol signal existing at high altitude from columnar AOT. The cloud aerosol imager (CAI) on GOSAT satellite has four observing wavelengths, 380, 670, 870 nm, and 1.6 μ m. In this work three channels are selected to estimate aerosol information. Look-up table (LUT) method is applied to estimate the optical properties

  3. Release 2 data products from the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler

    NASA Astrophysics Data System (ADS)

    Xu, Philippe Q.; Bhartia, Pawan K.; Jaross, Glen R.; DeLand, Matthew T.; Larsen, Jack C.; Fleig, Albert; Kahn, Daniel; Zhu, Tong; Chen, Zhong; Gorkavyi, Nick; Warner, Jeremy; Linda, Michael; Chen, Hong G.; Kowitt, Mark; Haken, Michael; Hall, Peter

    2014-10-01

    The OMPS Limb Profiler (LP) was launched on board the NASA Suomi National Polar-orbiting Partnership (SNPP) satellite in October 2011. OMPS-LP is a limb-scattering hyperspectral sensor that provides ozone profiling capability at 1.8 km vertical resolution from cloud top to 60 km altitude. The use of three parallel slits allows global coverage in approximately four days. We have recently completed a full reprocessing of all LP data products, designated as Release 2, that improves the accuracy and quality of these products. Level 1 gridded radiance (L1G) changes include intra-orbit and seasonal correction of variations in wavelength registration, revised static and intra-orbit tangent height adjustments, and simplified pixel selection from multiple images. Ozone profile retrieval changes include removal of the explicit aerosol correction, exclusion of channels contaminated by stratospheric OH emission, a revised instrument noise characterization, improved synthetic solar spectrum, improved pressure and temperature ancillary data, and a revised ozone climatology. Release 2 data products also include aerosol extinction coefficient profiles derived with the prelaunch retrieval algorithm. Our evaluation of OMPS LP Release 2 data quality is good. Zonal average ozone profile comparisons with Aura MLS data typically show good agreement, within 5-10% over the altitude range 20-50 km between 60°S and 60°N. The aerosol profiles agree well with concurrent satellite measurements such as CALIPSO and OSIRIS, and clearly detect exceptional events such as volcanic eruptions and the Chelyabinsk bolide in February 2013.

  4. Release 2 data products from the Ozone Mapping and Profiler Suite (OMPS) Limb Profiler

    NASA Technical Reports Server (NTRS)

    Xu, Q. Philippe; Bhartia, Pawan K.; Jaross, Glen R.; Deland, Matthew T.; Larsen, Jack C.; Fleig, Albert; Kahn, Daniel; Zhu, Tong; Chen, Zhong; Gorkavyi, Nick; hide

    2014-01-01

    The OMPS Limb Profiler (LP) was launched on board the NASA Suomi National Polar-orbiting Partnership (SNPP) satellite in October 2011. OMPS-LP is a limb-scattering hyperspectral sensor that provides ozone profiling capability at 1.5 km vertical resolution from cloud top to 60 km altitude. The use of three parallel slits allows global coverage in approximately four days. We have recently completed a full reprocessing of all LP data products, designated as Release 2, that improves the accuracy and quality of these products. Level 1 gridded radiance (L1G) changes include intra-orbit and seasonal correction of variations in wavelength registration, revised static and intra-orbit tangent height adjustments, and simplified pixel selection from multiple images. Ozone profile retrieval changes include removal of the explicit aerosol correction, exclusion of channels contaminated by stratospheric OH emission, a revised instrument noise characterization, improved synthetic solar spectrum, improved pressure and temperature ancillary data, and a revised ozone climatology. Release 2 data products also include aerosol extinction coefficient profiles derived with the prelaunch retrieval algorithm. Our evaluation of OMPS LP Release 2 data quality is good. Zonal average ozone profile comparisons with Aura MLS data typically show good agreement, within 5-10% over the altitude range 20-50 km between 60 deg S and 60 deg N. The aerosol profiles agree well with concurrent satellite measurements such as CALIPSO and OSIRIS, and clearly detect exceptional events such as volcanic eruptions and the Chelyabinsk bolide in February 2013.

  5. Simultaneous aerosol/ocean products retrieved during the 2014 SABOR campaign using the NASA Research Scanning Polarimeter (RSP)

    NASA Astrophysics Data System (ADS)

    Stamnes, S.; Hostetler, C. A.; Ferrare, R. A.; Hair, J. W.; Burton, S. P.; Liu, X.; Hu, Y.; Stamnes, K. H.; Chowdhary, J.; Brian, C.

    2017-12-01

    The SABOR (Ship-Aircraft Bio-Optical Research) campaign was conducted during the summer of 2014, in the Atlantic Ocean, over the Chesapeake Bay and the eastern coastal region of the United States. The NASA GISS Research Scanning Polarimeter, a multi-angle, multi-spectral polarimeter measured the upwelling polarized radiances from a B200 aircraft. We present results from the new "MAPP" algorithm for RSP that is based on optimal estimation and that can retrieve simultaneous aerosol microphysical properties (including effective radius, single-scattering albedo, and real refractive index) and ocean color products using accurate radiative transfer and Mie calculations. The algorithm was applied to data collected during SABOR to retrieve aerosol microphysics and ocean products for all Aerosols-Above-Ocean (AAO) scenes. The RSP MAPP products are compared against collocated aerosol extinction and backscatter profiles collected by the NASA LaRC airborne High Spectral Resolution Lidar (HSRL-1), including lidar depth profiles of the ocean diffuse attenuation coefficient and the hemispherical backscatter coefficient.

  6. In-Situ Measurements of Aerosol Optical Properties using New Cavity Ring-Down and Photoacoustics Instruments and Comparison with more Traditional Techniques

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Arnott, P.; Covert, D.; Elleman, R.; Ferrare, R.; Hallar, A. G.; Jonsson, H.; Kirchstetter, T. W.; Luu, A. P.; Ogren, J.

    2004-01-01

    Carbonaceous species (BC and OC) are responsible for most of the absorption associated with aerosol particles. The amount of radiant energy an aerosol absorbs has profound effects on climate and air quality. It is ironic that aerosol absorption coefficient is one of the most difficult aerosol properties to measure. A new cavity ring-down (CRD) instrument, called Cadenza (NASA-ARC), measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. Absorption coefficient is obtained from the difference of measured extinction and scattering within the instrument. Aerosol absorption coefficient is also measured by a photoacoustic (PA) instrument (DRI) that was operated on an aircraft for the first time during the DOE Aerosol Intensive Operating Period (IOP). This paper will report on measurements made with this new instrument and other in-situ instruments during two field recent field studies. The first field study was an airborne cam;oaign, the DOE Aerosol Intensive Operating Period flown in May, 2003 over northern Oklahoma. One of the main purposes of the IOP was to assess our ability to measure extinction and absorption coefficient in situ. This paper compares measurements of these aerosol optical properties made by the CRD, PA, nephelometer, and Particle Soot Absorption Photometer (PSAP) aboard the CIRPAS Twin-Otter. During the IOP, several significant aerosol layers were sampled aloft. These layers are identified in the remote (AATS-14) as well as in situ measurements. Extinction profiles measured by Cadenza are compared to those derived from the Ames Airborne Tracking Sunphotometer (AATS-14, NASA-ARC). The regional radiative impact of these layers is assessed by using the measured aerosol optical properties in a radiative transfer model. The second study was conducted in the Caldecott Tunnel, a heavily-used tunnel located north of San Francisco, Ca. The aerosol sampled in this study was

  7. The Measurement of Aerosol Optical Properties Using Continuous Wave Cavity Ring-Down Techniques

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Owano, T.; Castaneda, R.; Baer, D. S.; Paldus, B. A.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Large uncertainties in the effects that aerosols have on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This abstract describes the use of continuous wave cavity ring-down (CW-CRD) technology to address this problem. The innovations in this instrument are the use of CW-CRD to measure aerosol extinction coefficient, the simultaneous measurement of scattering coefficient, and small size suitable for a wide range of aircraft applications. Our prototype instrument measures extinction and scattering coefficient at 690 nm and extinction coefficient at 1550 nm. The instrument itself is small (60 x 48 x 15 cm) and relatively insensitive to vibrations. The prototype instrument has been tested in our lab and used in the field. While improvements in performance are needed, the prototype has been shown to make accurate and sensitive measurements of extinction and scattering coefficients. Combining these two parameters, one can obtain the single-scattering albedo and absorption coefficient, both important aerosol properties. The use of two wavelengths also allows us to obtain a quantitative idea of the size of the aerosol through the Angstrom exponent. Minimum sensitivity of the prototype instrument is 1.5 x 10(exp -6)/m (1.5/Mm). Validation of the measurement of extinction coefficient has been accomplished by comparing the measurement of calibration spheres with Mie calculations. This instrument and its successors have potential to help reduce uncertainty currently associated with aerosol optical properties and their spatial and temporal variation. Possible applications include studies of visibility, climate forcing by aerosol, and the validation of aerosol retrieval schemes from satellite data.

  8. Spectral signatures of polar stratospheric clouds and sulfate aerosol

    NASA Technical Reports Server (NTRS)

    Massie, S. T.; Bailey, P. L.; Gille, J. C.; Lee, E. C.; Mergenthaler, J. L.; Roche, A. E.; Kumer, J. B.; Fishbein, E. F.; Waters, J. W.; Lahoz, W. A.

    1994-01-01

    Multiwavelength observations of Antarctic and midlatitude aerosol by the Cryogenic Limb Array Etalon Spectrometer (CLAES) experiment on the Upper Atmosphere Research Satellite (UARS) are used to demonstrate a technique that identifies the location of polar stratospheric clouds. The technique discussed uses the normalized area of the triangle formed by the aerosol extinctions at 925, 1257, and 1605/cm (10.8, 8.0, and 6.2 micrometers) to derive a spectral aerosol measure M of the aerosol spectrum. Mie calculations for spherical particles and T-matrix calculations for spheriodal particles are used to generate theoretical spectral extinction curves for sulfate and polar stratospheric cloud particles. The values of the spectral aerosol measure M for the sulfate and polar stratospheric cloud particles are shown to be different. Aerosol extinction data, corresponding to temperatures between 180 and 220 K at a pressure of 46 hPa (near 21-km altitude) for 18 August 1992, are used to demonstrate the technique. Thermodynamic calculations, based upon frost-point calculations and laboratory phase-equilibrium studies of nitric acid trihydrate, are used to predict the location of nitric acid trihydrate cloud particles.

  9. Vertically resolved aerosol properties by multi-wavelength lidar measurements

    NASA Astrophysics Data System (ADS)

    Perrone, M. R.; De Tomasi, F.; Gobbi, G. P.

    2014-02-01

    An approach based on the graphical method of Gobbi and co-authors (2007) is introduced to estimate the dependence on altitude of the aerosol fine mode radius (Rf) and of the fine mode contribution (η) to the aerosol optical thickness (AOT) from three-wavelength lidar measurements. The graphical method of Gobbi and co-authors (2007) was applied to AERONET (AErosol RObotic NETwork) spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (å) and its spectral curvature Δå. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of å and Δå and to estimate the dependence on altitude of Rf and η(532 nm) from the å-Δå combined analysis. Lidar measurements were performed at the Department of Mathematics and Physics of the Universita' del Salento, in south-eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south-eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to ten measurement days to demonstrate its feasibility in different aerosol load conditions. The selected days were characterized by AOTs spanning the 0.26-0.67, 0.15-0.39, and 0.04-0.27 range at 355, 532, and 1064 nm, respectively. Mean lidar ratios varied within the 31-83, 32-84, and 11-47 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. å values calculated from lidar extinction profiles at 355 and 1064 nm ranged between 0.1 and 2.5 with a mean value ± 1 standard deviation equal to 1.3 ± 0.7. Δå varied within the -0.1-1 range with mean value equal to 0.25 ± 0.43. Rf and η(532 nm) values spanning the 0.05-0.3 μm and the 0.3-0.99 range, respectively, were associated with the å-Δå data points. Rf and η values showed no dependence on the altitude. 60

  10. Transportable Rayleigh/Raman lidar for aerosol and water vapor profiling

    NASA Astrophysics Data System (ADS)

    Congeduti, Fernando; D'Aulerio, P.; Casadio, S.; Baldetti, P.; Belardinelli, F.

    2001-01-01

    A nighttime operating Raman/Rayleigh/Mie lidar system for the measurement of profiles of the water vapor mixing ratio and the aerosol backscatter ratio is described. The transmitter utilizes two laser beam at 532 nm and 355 nm from a Nd:YAG pulsed laser and the receiver consists of three Newtonian telescopes. Optical fibers carry the signal to the detectors. The system, which is installed in two containers, is transportable. Data are recorded with resolutions of 75-m in altitude and 1-min in time. Water vapor profiles from 200 m above the lidar altitude up to the upper troposphere and aerosol profiles form 500 m up to the lower stratosphere were obtained also at the lowest resolution. The lidar was deployed and used in the 'Target Area of the Lago Maggiore' during the MAP-SOP international campaign. Measurements taken during that campaign are reported to show the lidar performance. Improvements of the system by employing an array of nine 50-cm diameter telescopes are planned. These should effectively enhance the lidar performance.

  11. Source apportionment of PM2.5 light extinction in an urban atmosphere in China.

    PubMed

    Lan, Zijuan; Zhang, Bin; Huang, Xiaofeng; Zhu, Qiao; Yuan, Jinfeng; Zeng, Liwu; Hu, Min; He, Lingyan

    2018-01-01

    Haze in China is primarily caused by high pollution of atmospheric fine particulates (PM 2.5 ). However, the detailed source structures of PM 2.5 light extinction have not been well established, especially for the roles of various organic aerosols, which makes haze management lack specified targets. This study obtained the mass concentrations of the chemical compositions and the light extinction coefficients of fine particles in the winter in Dongguan, Guangdong Province, using high time resolution aerosol observation instruments. We combined the positive matrix factor (PMF) analysis model of organic aerosols and the multiple linear regression method to establish a quantitative relationship model between the main chemical components, in particular the different sources of organic aerosols and the extinction coefficients of fine particles with a high goodness of fit (R 2 =0.953). The results show that the contribution rates of ammonium sulphate, ammonium nitrate, biomass burning organic aerosol (BBOA), secondary organic aerosol (SOA) and black carbon (BC) were 48.1%, 20.7%, 15.0%, 10.6%, and 5.6%, respectively. It can be seen that the contribution of the secondary aerosols is much higher than that of the primary aerosols (79.4% versus 20.6%) and are a major factor in the visibility decline. BBOA is found to have a high visibility destroying potential, with a high mass extinction coefficient, and was the largest contributor during some high pollution periods. A more detailed analysis indicates that the contribution of the enhanced absorption caused by BC mixing state was approximately 37.7% of the total particle absorption and should not be neglected. Copyright © 2017. Published by Elsevier B.V.

  12. Vertical profiles of aerosol and black carbon in the Arctic: a seasonal phenomenology along 2 years (2011-2012) of field campaigns

    NASA Astrophysics Data System (ADS)

    Ferrero, Luca; Cappelletti, David; Busetto, Maurizio; Mazzola, Mauro; Lupi, Angelo; Lanconelli, Christian; Becagli, Silvia; Traversi, Rita; Caiazzo, Laura; Giardi, Fabio; Moroni, Beatrice; Crocchianti, Stefano; Fierz, Martin; Močnik, Griša; Sangiorgi, Giorgia; Perrone, Maria G.; Maturilli, Marion; Vitale, Vito; Udisti, Roberto; Bolzacchini, Ezio

    2016-10-01

    We present results from a systematic study of vertical profiles of aerosol number size distribution and black carbon (BC) concentrations conducted in the Arctic, over Ny-Ålesund (Svalbard). The campaign lasted 2 years (2011-2012) and resulted in 200 vertical profiles measured by means of a tethered balloon (up to 1200 m a.g.l.) during the spring and summer seasons. In addition, chemical analysis of filter samples, aerosol size distribution and a full set of meteorological parameters were determined at ground. The collected experimental data allowed a classification of the vertical profiles into different typologies, which allowed us to describe the seasonal phenomenology of vertical aerosol properties in the Arctic. During spring, four main types of profiles were found and their behavior was related to the main aerosol and atmospheric dynamics occurring at the measuring site. Background conditions generated homogenous profiles. Transport events caused an increase of aerosol concentration with altitude. High Arctic haze pollution trapped below thermal inversions promoted a decrease of aerosol concentration with altitude. Finally, ground-based plumes of locally formed secondary aerosol determined profiles with decreasing aerosol concentration located at different altitude as a function of size. During the summer season, the impact from shipping caused aerosol and BC pollution plumes to be constrained close to the ground, indicating that increasing shipping emissions in the Arctic could bring anthropogenic aerosol and BC in the Arctic summer, affecting the climate.

  13. Aerosol properties computed from aircraft-based observations during the ACE- Asia campaign. 2; A case study of lidar ratio closure and aerosol radiative effects

    NASA Technical Reports Server (NTRS)

    Kuzmanoski, Maja; Box, M. A.; Schmid, B.; Box, G. P.; Wang, J.; Russell, P. B.; Bates, D.; Jonsson, H. H.; Welton, Ellsworth J.; Flagan, R. C.

    2005-01-01

    For a vertical profile with three distinct layers (marine boundary, pollution and dust), observed during the ACE-Asia campaign, we carried out a comparison between the modeled lidar ratio vertical profile and that obtained from collocated airborne NASA AATS-14 sunphotometer and shipborne Micro-Pulse Lidar (MPL) measurements. Vertically resolved lidar ratio was calculated from two size distribution vertical profiles - one obtained by inversion of sunphotometer-derived extinction spectra, and one measured in-situ - combined with the same refractive index model based on aerosol chemical composition. The aerosol model implies single scattering albedos of 0.78 - 0.81 and 0.93 - 0.96 at 0.523 microns (the wavelength of the lidar measurements), in the pollution and dust layers, respectively. The lidar ratios calculated from the two size distribution profiles have close values in the dust layer; they are however, significantly lower than the lidar ratios derived from combined lidar and sunphotometer measurements, most probably due to the use of a simple nonspherical model with a single particle shape in our calculations. In the pollution layer, the two size distribution profiles yield generally different lidar ratios. The retrieved size distributions yield a lidar ratio which is in better agreement with that derived from lidar/sunphotometer measurements in this layer, with still large differences at certain altitudes (the largest relative difference was 46%). We explain these differences by non-uniqueness of the result of the size distribution retrieval and lack of information on vertical variability of particle refractive index. Radiative transfer calculations for this profile showed significant atmospheric radiative forcing, which occurred mainly in the pollution layer. We demonstrate that if the extinction profile is known then information on the vertical structure of absorption and asymmetry parameter is not significant for estimating forcing at TOA and the surface

  14. Information Retrieval from SAGE II and MFRSR Multi-Spectral Extinction Measurements

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew A.; Hansen, James E. (Technical Monitor)

    2001-01-01

    Direct beam spectral extinction measurements of solar radiation contain important information on atmospheric composition in a form that is essentially free from multiple scattering contributions that otherwise tend to complicate the data analysis and information retrieval. Such direct beam extinction measurements are available from the solar occultation satellite-based measurements made by the Stratospheric and Aerosol Gas Experiment (SAGE II) instrument and by ground-based Multi-Filter Shadowband Radiometers (MFRSRs). The SAGE II data provide cross-sectional slices of the atmosphere twice per orbit at seven wavelengths between 385 and 1020 nm with approximately 1 km vertical resolution, while the MFRSR data provide atmospheric column measurements at six wavelengths between 415 and 940 nm but at one minute time intervals. We apply the same retrieval technique of simultaneous least-squares fit to the observed spectral extinctions to retrieve aerosol optical depth, effective radius and variance, and ozone, nitrogen dioxide, and water vapor amounts from the SAGE II and MFRSR measurements. The retrieval technique utilizes a physical model approach based on laboratory measurements of ozone and nitrogen dioxide extinction, line-by-line and numerical k-distribution calculations for water vapor absorption, and Mie scattering constraints on aerosol spectral extinction properties. The SAGE II measurements have the advantage of being self-calibrating in that deep space provides an effective zero point for the relative spectral extinctions. The MFRSR measurements require periodic clear-day Langley regression calibration events to maintain accurate knowledge of instrument calibration.

  15. A Decade of Global Lidar Cloud and Aerosol Profiling

    NASA Astrophysics Data System (ADS)

    Winker, D. M.

    2016-12-01

    The CALIPSO satellite was developed as a collaboration between NASA and CNES with the objective of globally profiling aerosols and clouds for the first time. Launched in April 2006, CALIPSO has now flown for a decade as part of the A-train satellite constellation, producing an unprecedented 3D observational record and more than a thousand publications to date. Originally planned as a three-year mission, the unanticipated duration of the CALIPSO mission has allowed the characterization of seasonal and interannual variability of aerosols and clouds. This presentation will discuss highlights among the scientific findings from CALIPSO, including contributions to our understanding of Earth's climate and climate change.

  16. Lidar sprectroscopy instrument (LISSI): An infrastructure facility for chemical aerosol profiling at the University of Hertfordshire

    NASA Astrophysics Data System (ADS)

    Tesche, Matthias; Tatarov, Boyan; Noh, Youngmin; Müller, Detlef

    2018-04-01

    The lidar development at the University of Hertfordshire explores the feasibility of using Raman backscattering for chemical aerosol profiling. This paper provides an overview of the new facility. A high-power Nd:YAG/OPO setup is used to excite Raman backscattering at a wide range of wavelengths. The receiver combines a spectrometer with a 32-channel detector or an ICCD camera to resolve Raman signals of various chemical compounds. The new facility will open new avenues for chemical profiling of aerosol pollution from measurements of Raman scattering by selected chemical compounds, provide data that allow to close the gap between optical and microphysical aerosol profiling with lidar and enables connecting lidar measurements to parameters used in atmospheric modelling.

  17. Spatial Interpolation of Aerosol Optical Depth Pollution: Comparison of Methods for the Development of Aerosol Distribution

    NASA Astrophysics Data System (ADS)

    Safarpour, S.; Abdullah, K.; Lim, H. S.; Dadras, M.

    2017-09-01

    Air pollution is a growing problem arising from domestic heating, high density of vehicle traffic, electricity production, and expanding commercial and industrial activities, all increasing in parallel with urban population. Monitoring and forecasting of air quality parameters are important due to health impact. One widely available metric of aerosol abundance is the aerosol optical depth (AOD). The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. Seasonal aerosol optical depth (AOD) values at 550 nm derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's Terra satellites, for the 10 years period of 2000 - 2010 were used to test 7 different spatial interpolation methods in the present study. The accuracy of estimations was assessed through visual analysis as well as independent validation based on basic statistics, such as root mean square error (RMSE) and correlation coefficient. Based on the RMSE and R values of predictions made using measured values from 2000 to 2010, Radial Basis Functions (RBFs) yielded the best results for spring, summer and winter and ordinary kriging yielded the best results for fall.

  18. Optical extinction efficiency measurements on fine and accumulation mode aerosol using single particle cavity ring-down spectroscopy.

    PubMed

    Cotterell, Michael I; Mason, Bernard J; Preston, Thomas C; Orr-Ewing, Andrew J; Reid, Jonathan P

    2015-06-28

    A new experiment is presented for the measurement of single aerosol particle extinction efficiencies, Qext, combining cavity ring-down spectroscopy (CRDS, λ = 405 nm) with a Bessel beam trap (λ = 532 nm) in tandem with phase function (PF) measurements. This approach allows direct measurements of the changing optical cross sections of individual aerosol particles over indefinite time-frames facilitating some of the most comprehensive measurements of the optical properties of aerosol particles so far made. Using volatile 1,2,6-hexanetriol droplets, Qext is measured over a continuous radius range with the measured Qext envelope well described by fitted cavity standing wave (CSW) Mie simulations. These fits allow the refractive index at 405 nm to be determined. Measurements are also presented of Qext variation with RH for two hygroscopic aqueous inorganic systems ((NH4)2SO4 and NaNO3). For the PF and the CSW Mie simulations, the refractive index, nλ, is parameterised in terms of the particle radius. The radius and refractive index at 532 nm are determined from PFs, while the refractive index at 405 nm is determined by comparison of the measured Qext to CSW Mie simulations. The refractive indices determined at the shorter wavelength are larger than at the longer wavelength consistent with the expected dispersion behaviour. The measured values at 405 nm are compared to estimates from volume mixing and molar refraction mixing rules, with the latter giving superior agreement. In addition, the first single-particle Qext measurements for accumulation mode aerosol are presented for droplets with radii as small as ∼300 nm.

  19. Characterizing Aerosol Distributions and Optical Properties Using the NASA Langley High Spectral Resolution Lidar

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hostetler, Chris; Ferrare, Richard

    The objective of this project was to provide vertically and horizontally resolved data on aerosol optical properties to assess and ultimately improve how models represent these aerosol properties and their impacts on atmospheric radiation. The approach was to deploy the NASA Langley Airborne High Spectral Resolution Lidar (HSRL) and other synergistic remote sensors on DOE Atmospheric Science Research (ASR) sponsored airborne field campaigns and synergistic field campaigns sponsored by other agencies to remotely measure aerosol backscattering, extinction, and optical thickness profiles. Synergistic sensors included a nadir-viewing digital camera for context imagery, and, later in the project, the NASA Goddard Institutemore » for Space Studies (GISS) Research Scanning Polarimeter (RSP). The information from the remote sensing instruments was used to map the horizontal and vertical distribution of aerosol properties and type. The retrieved lidar parameters include profiles of aerosol extinction, backscatter, depolarization, and optical depth. Products produced in subsequent analyses included aerosol mixed layer height, aerosol type, and the partition of aerosol optical depth by type. The lidar products provided vertical context for in situ and remote sensing measurements from other airborne and ground-based platforms employed in the field campaigns and was used to assess the predictions of transport models. Also, the measurements provide a data base for future evaluation of techniques to combine active (lidar) and passive (polarimeter) measurements in advanced retrieval schemes to remotely characterize aerosol microphysical properties. The project was initiated as a 3-year project starting 1 January 2005. It was later awarded continuation funding for another 3 years (i.e., through 31 December 2010) followed by a 1-year no-cost extension (through 31 December 2011). This project supported logistical and flight costs of the NASA sensors on a dedicated aircraft, the

  20. The Measurement of Aerosol Optical Properties using Continuous Wave Cavity Ring-Down Techniques

    NASA Technical Reports Server (NTRS)

    Strawa, Anthony W.; Castaneda, Rene; Owano, Thomas; Baer, Douglas S.; Paldus, Barbara A.; Gore, Warren J. (Technical Monitor)

    2002-01-01

    Large uncertainties in the effects that aerosols have on climate require improved in situ measurements of extinction coefficient and single-scattering albedo. This paper describes the use of continuous wave cavity ring-down (CW-CRD) technology to address this problem. The innovations in this instrument are the use of CW-CRD to measure aerosol extinction coefficient, the simultaneous measurement of scattering coefficient, and small size suitable for a wide range of aircraft applications. Our prototype instrument measures extinction and scattering coefficient at 690 nm and extinction coefficient at 1550 nm. The instrument itself is small (60 x 48 x 15 cm) and relatively insensitive to vibrations. The prototype instrument has been tested in our lab and used in the field. While improvements in performance are needed, the prototype has been shown to make accurate and sensitive measurements of extinction and scattering coefficients. Combining these two parameters, one can obtain the single-scattering albedo and absorption coefficient, both important aerosol properties. The use of two wavelengths also allows us to obtain a quantitative idea of the size of the aerosol through the Angstrom exponent. Minimum sensitivity of the prototype instrument is 1.5 x 10(exp -6)/m (1.5 M/m). Validation of the measurement of extinction coefficient has been accomplished by comparing the measurement of calibration spheres with Mie calculations. This instrument and its successors have potential to help reduce uncertainty currently associated with aerosol optical properties and their spatial and temporal variation. Possible applications include studies of visibility, climate forcing by aerosol, and the validation of aerosol retrieval schemes from satellite data.

  1. Evaluating Global Aerosol Models and Aerosol and Water Vapor Properties Near Clouds

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Richard A. Ferrare; David D. Turner

    Project goals: (1) Use the routine surface and airborne measurements at the ARM SGP site, and the routine surface measurements at the NSA site, to continue our evaluations of model aerosol simulations; (2) Determine the degree to which the Raman lidar measurements of water vapor and aerosol scattering and extinction can be used to remotely characterize the aerosol humidification factor; (3) Use the high temporal resolution CARL data to examine how aerosol properties vary near clouds; and (4) Use the high temporal resolution CARL and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds.

  2. Evaluation, Feasibility, and Design of a Three-Wavelength Infrared Atmospheric Aerosol Extinctiometer.

    DTIC Science & Technology

    1980-09-02

    laser or searchlight measurements . The study program consisted of three basic tasks: (1) a review of existing techniques for measuring aerosol extinction ...to aerosol extinction along a path can be deduced. Solutions to this problcaii fall into several classes. One class of solutions invoLves measuring ...employed such a windowless system to measure the absorption of an artificial aerosol consisting of quartz particles, using a CO 2 laser in the

  3. Observations and projections of visibility and aerosol optical thickness (1956-2100) in the Netherlands: impacts of time-varying aerosol composition and hygroscopicity

    NASA Astrophysics Data System (ADS)

    Boers, R.; van Weele, M.; van Meijgaard, E.; Savenije, M.; Siebesma, A. P.; Bosveld, F.; Stammes, P.

    2015-01-01

    Time series of visibility and aerosol optical thickness for the Netherlands have been constructed for 1956-2100 based on observations and aerosol mass scenarios. Aerosol optical thickness from 1956 to 2013 has been reconstructed by converting time series of visibility to visible extinction which in turn are converted to aerosol optical thickness using an appropriate scaling depth. The reconstruction compares closely with remote sensing observations of aerosol optical thickness between 1960 and 2013. It appears that aerosol optical thickness was relatively constant over the Netherlands in the years 1955-1985. After 1985, visibility has improved, while at the same time aerosol optical thickness has decreased. Based on aerosol emission scenarios for the Netherlands three aerosol types have been identified: (1) a constant background consisting of sea salt and mineral dust, (2) a hydrophilic anthropogenic inorganic mixture, and (3) a partly hydrophobic mixture of black carbon (BC) and organic aerosols (OAs). A reduction in overall aerosol concentration turns out to be the most influential factor in the reduction in aerosol optical thickness. But during 1956-1985, an upward trend in hydrophilic aerosols and associated upward trend in optical extinction has partly compensated the overall reduction in optical extinction due to the reduction in less hydrophilic BC and OAs. A constant optical thickness ensues. This feature highlights the influence of aerosol hygroscopicity on time-varying signatures of atmospheric optical properties. Within the hydrophilic inorganic aerosol mixture there is a gradual shift from sulfur-based (1956-1985) to a nitrogen-based water aerosol chemistry (1990 onwards) but always modulated by the continual input of sodium from sea salt. From 2013 to 2100, visibility is expected to continue its increase, while at the same time optical thickness is foreseen to continue to decrease. The contribution of the hydrophilic mixture to the aerosol optical

  4. HSRL-2 Observations of Aerosol Variability During an Aerosol Build-up Event in Houston and Comparisons With WRF-Chem

    NASA Technical Reports Server (NTRS)

    Burton, Sharon P.; Saide, Pablo; Sawamura, Patricia; Hostetler, Chris; Ferrare, Rich; Scarino, Amy Jo; Berkoff, Tim; Harper, David; Cook, Tony; Rogers, Ray; hide

    2015-01-01

    The NASA Langley airborne multi-wavelength High Spectral Resolution Lidar (HSRL-2) provides vertical distribution of aerosol optical properties as curtains of aerosol extinction, backscatter and depolarization along the flight track, plus intensive properties that are used to infer aerosol type and external mixing of types. Deployed aboard the NASA Langley King Air on the DISCOVER-AQ field mission in Houston in September 2013, HSRL-2 flew a pattern that included 18 ground sites, repeated four times a day, coordinated with a suite of airborne in situ measurements. The horizontally and vertically resolved curtains of HSRL-2 measurements give an unparalleled view of the spatial and temporal variability of aerosol, which provide broad context for interpreting other measurements and models. Detailed comparisons of aerosol extinction are made with the WRF-Chem chemical transport model along the HSRL-2 flight path. The period from Sept. 11-14 is notable for a large aerosol build-up and persistent smoke layers. We investigate the aerosol properties using the vertically resolved HSRL-2 measurements and aerosol typing analysis plus WRFChem model tracers and back trajectories, and modeling of humidification effects.

  5. Evaluation on Asian Dust Aerosol and Simulated Processes in CanAM4.2 Using Satellite Measurements and Station Data

    NASA Astrophysics Data System (ADS)

    Yiran, P.; Li, J.; von Salzen, K.; Dai, T.; Liu, D.

    2014-12-01

    Mineral dust is a significant contributor to global and Asian aerosol burden. Currently, large uncertainties still exist in simulated aerosol processes in global climate models (GCMs), which lead to a diversity in dust mass loading and spatial distribution of GCM projections. In this study, satellite measurements from CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) and observed aerosol data from Asian stations are compared with modelled aerosol in the Canadian Atmospheric Global Climate Model (CanAM4.2). Both seasonal and annual variations in Asian dust distribution are investigated. Vertical profile of simulated aerosol in troposphere is evaluated with CALIOP Level 3 products and local observed extinction for dust and total aerosols. Physical processes in GCM such as horizontal advection, vertical mixing, dry and wet removals are analyzed according to model simulation and available measurements of aerosol. This work aims to improve current understanding of Asian dust transport and vertical exchange on a large scale, which may help to increase the accuracy of GCM simulation on aerosols.

  6. Vertical profiles of aerosol absorption coefficient from micro-Aethalometer data and Mie calculation over Milan.

    PubMed

    Ferrero, L; Mocnik, G; Ferrini, B S; Perrone, M G; Sangiorgi, G; Bolzacchini, E

    2011-06-15

    Vertical profiles of aerosol number-size distribution and black carbon (BC) concentration were measured between ground-level and 500m AGL over Milan. A tethered balloon was fitted with an instrumentation package consisting of the newly-developed micro-Aethalometer (microAeth® Model AE51, Magee Scientific, USA), an optical particle counter, and a portable meteorological station. At the same time, PM(2.5) samples were collected both at ground-level and at a high altitude sampling site, enabling particle chemical composition to be determined. Vertical profiles and PM(2.5) data were collected both within and above the mixing layer. Absorption coefficient (b(abs)) profiles were calculated from the Aethalometer data: in order to do so, an optical enhancement factor (C), accounting for multiple light-scattering within the filter of the new microAeth® Model AE51, was determined for the first time. The value of this parameter C (2.05±0.03 at λ=880nm) was calculated by comparing the Aethalometer attenuation coefficient and aerosol optical properties determined from OPC data along vertical profiles. Mie calculations were applied to the OPC number-size distribution data, and the aerosol refractive index was calculated using the effective medium approximation applied to aerosol chemical composition. The results compare well with AERONET data. The BC and b(abs) profiles showed a sharp decrease at the mixing height (MH), and fairly constant values of b(abs) and BC were found above the MH, representing 17±2% of those values measured within the mixing layer. The BC fraction of aerosol volume was found to be lower above the MH: 48±8% of the corresponding ground-level values. A statistical mean profile was calculated, both for BC and b(abs), to better describe their behaviour; the model enabled us to compute their average behaviour as a function of height, thus laying the foundations for valid parametrizations of vertical profile data which can be useful in both remote sensing

  7. Spatial variation of stratospheric aerosol acidity and model refractive index - Implications of recent results

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Hamill, P.

    1984-01-01

    Recent experimental results indicate that little or no solid ammonium sulfate is present in background stratospheric aerosols. Other results allow straightforward calculation of sulfuric acid/water droplet properties (acidity, specific gravity, refractive index) as functions of stratospheric temperature and humidity. These results are combined with a variety of latitudinal and seasonal temperature and humidity profiles to obtain corresponding profiles of droplet properties. These profiles are used to update a previous model of stratospheric aerosol refractive index. The new model retains the simplifying approximation of vertically constant refractive index in the inner stratosphere, but has sulfuric acid/water refractive index values that significantly exceed the previously used room temperature values. Mean conversion ratios (e.g., extinction-to-number, backscatter-to-volume) obtained using Mie scattering calculations with the new refractive indices are very similar to those obtained for the old indices, because the effects of deleting ammonium sulfate and increasing acid indices tend to cancel each other.

  8. The Complex Refractive Index of Volcanic Ash Aerosol Retrieved From Spectral Mass Extinction

    NASA Astrophysics Data System (ADS)

    Reed, Benjamin E.; Peters, Daniel M.; McPheat, Robert; Grainger, R. G.

    2018-01-01

    The complex refractive indices of eight volcanic ash samples, chosen to have a representative range of SiO2 contents, were retrieved from simultaneous measurements of their spectral mass extinction coefficient and size distribution. The mass extinction coefficients, at 0.33-19 μm, were measured using two optical systems: a Fourier transform spectrometer in the infrared and two diffraction grating spectrometers covering visible and ultraviolet wavelengths. The particle size distribution was measured using a scanning mobility particle sizer and an optical particle counter; values for the effective radius of ash particles measured in this study varied from 0.574 to 1.16 μm. Verification retrievals on high-purity silica aerosol demonstrated that the Rayleigh continuous distribution of ellipsoids (CDEs) scattering model significantly outperformed Mie theory in retrieving the complex refractive index, when compared to literature values. Assuming the silica particles provided a good analogue of volcanic ash, the CDE scattering model was applied to retrieve the complex refractive index of the eight ash samples. The Lorentz formulation of the complex refractive index was used within the retrievals as a convenient way to ensure consistency with the Kramers-Kronig relation. The short-wavelength limit of the electric susceptibility was constrained by using independently measured reference values of the complex refractive index of the ash samples at a visible wavelength. The retrieved values of the complex refractive indices of the ash samples showed considerable variation, highlighting the importance of using accurate refractive index data in ash cloud radiative transfer models.

  9. Stratospheric aerosol optical depths, 1850-1990

    NASA Technical Reports Server (NTRS)

    Sato, Makiko; Hansen, James E.; Mccormick, M. Patrick; Pollack, James B.

    1993-01-01

    A global stratospheric aerosol database employed for climate simulations is described. For the period 1883-1990, aerosol optical depths are estimated from optical extinction data, whose quality increases with time over that period. For the period 1850-1882, aerosol optical depths are more crudely estimated from volcanological evidence for the volume of ejecta from major known volcanoes. The data set is available over Internet.

  10. A climatology of stratospheric aerosol

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hitchman, M.H.; Mckay, M.; Trepte, C.R.

    1994-10-01

    A global climatology of stratospheric aerosol is created by combining nearly a decade (1979-1981 and 1984-1990) of contemporaneous observations from the Stratospheric Aerosol and Gas Experiment (SAGE I and II) and Stratospheric Aerosol Measurement (SAM II) instruments. One goal of this work is to provide a representative distribution of the aerosol layer for use in radiative and chemical modeling. A table of decadal average 1 micron extinction values is included, extending from the tropopause to 35 km and 80 deg S to 85 deg N, which allows estimation of surface area density. We find that the aerosol layer is distinctlymore » volcanic in nature and suggest that the decadal average is a more useful estimate of future aerosol loading than a `background` loading, which is never clearly achieved during the data record. This climatology lends insight into the general circulation of the stratosphere. Latitude - altitude sections of extinction radio at 1 micron are shown, average by decade, season, and phase of the quasi-biennial oscillation (QBO). A tropical reservoir region is diagnosed, with an `upper` and a `lower` transport regime. In the tropics above 22 km (upper regime), enhanced lofting occurs in the summer, with suppressed lofting or eddy dilution in the winter. In the extratropics within two scale heights of the tropopause (lower regime), poleward and downward transport is most robust during winter, especially in the northern hemisphere. The transport patterns persist into the subsequent equinoctial season. Ascent associated with QBO easterly shear favors detrainment in the upper regime, while relative descent and poleward spreading during QBO westerly shear favors detrainment in the lower regime. Extinction radio differences between the winter-spring and summer-fall hemispheres, and differences between the two phases of the QBO, are typically 20-50%.« less

  11. Reallocation in modal aerosol models: impacts on predicting aerosol radiative effects

    NASA Astrophysics Data System (ADS)

    Korhola, T.; Kokkola, H.; Korhonen, H.; Partanen, A.-I.; Laaksonen, A.; Lehtinen, K. E. J.; Romakkaniemi, S.

    2013-08-01

    In atmospheric modelling applications the aerosol particle size distribution is commonly represented by modal approach, in which particles in different size ranges are described with log-normal modes within predetermined size ranges. Such method includes numerical reallocation of particles from a mode to another for example during particle growth, leading to potentially artificial changes in the aerosol size distribution. In this study we analysed how this reallocation affects climatologically relevant parameters: cloud droplet number concentration, aerosol-cloud interaction coefficient and light extinction coefficient. We compared these parameters between a modal model with and without reallocation routines, and a high resolution sectional model that was considered as a reference model. We analysed the relative differences of the parameters in different experiments that were designed to cover a wide range of dynamic aerosol processes occurring in the atmosphere. According to our results, limiting the allowed size ranges of the modes and the following numerical remapping of the distribution by reallocation, leads on average to underestimation of cloud droplet number concentration (up to 100%) and overestimation of light extinction (up to 20%). The analysis of aerosol first indirect effect is more complicated as the ACI parameter can be either over- or underestimated by the reallocating model, depending on the conditions. However, for example in the case of atmospheric new particle formation events followed by rapid particle growth, the reallocation can cause around average 10% overestimation of the ACI parameter. Thus it is shown that the reallocation affects the ability of a model to estimate aerosol climate effects accurately, and this should be taken into account when using and developing aerosol models.

  12. Cavity Ring-Down Measurement of Aerosol Optical Properties During the Asian Dust Above Monterey Experiment and DOE Aerosol Intensive Operating Period

    NASA Technical Reports Server (NTRS)

    Ricci, K.; Strawa, A. W.; Provencal, R.; Castaneda, R.; Bucholtz, A.; Schmid, B.

    2004-01-01

    Large uncertainties in the effects of aerosols on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This paper describes preliminary results from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument designed to address these uncertainties. Cadenza measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. In the past year Cadenza was deployed in the Asian Dust Above Monterey (ADAM) and DOE Aerosol Intensive Operating Period (IOP) field projects. During these flights Cadenza produced measurements of aerosol extinction in the range from 0.2 to 300/Mm with an estimated precision of 0.1/Mm for 1550 nm light and 0.2/Mm for 675 nm light. Cadenza data from the ADAM and Aerosol IOP missions compared favorably with data from the other instruments aboard the CIRPAS Twin Otter aircraft and participating in those projects. We present comparisons between the Cadenza measurements and those from a TSI nephelometer, Particle Soot Absorption Photometer (PSAP), and the AATS 14 sun-photometer. Measurements of the optical properties of smoke and dust plumes sampled during these campaigns are presented and estimates of heating rates due to these plumes are made.

  13. Cavity Ring-Down Measurement of Aerosol Optical Properties During the Asian Dust Above Monterey Experiment and DOE Aerosol Intensive Operating Period

    NASA Astrophysics Data System (ADS)

    Ricci, K.; Strawa, A. W.; Provencal, R.; Castaneda, R.; Bucholtz, A.; Schmid, B.

    2003-12-01

    Large uncertainties in the effects of aerosols on climate require improved in-situ measurements of extinction coefficient and single-scattering albedo. This paper describes preliminary results from Cadenza, a new continuous wave cavity ring-down (CW-CRD) instrument designed to address these uncertainties. Cadenza measures the aerosol extinction coefficient for 675 nm and 1550 nm light, and simultaneously measures the scattering coefficient at 675 nm. In the past year Cadenza was deployed in the Asian Dust Above Monterey (ADAM) and DOE Aerosol Intensive Operating Period (IOP) field projects. During these flights Cadenza produced measurements of aerosol extinction in the range from 0.2 to 300 Mm-1 with an estimated precision of 0.1 Mm-1 for 1550 nm light and 0.2 Mm-1 for 675 nm light. Cadenza data from the ADAM and Aerosol IOP missions compared favorably with data from the other instruments aboard the CIRPAS Twin Otter aircraft and participating in those projects. We present comparisons between the Cadenza measurements and those from a TSI nephelometer, Particle Soot Absorption Photometer (PSAP), and the AATS14 sun-photometer. Measurements of the optical properties of smoke and dust plumes sampled during these campaigns are presented and estimates of heating rates due to these plumes are made.

  14. Estimation of desert-dust-related ice nuclei profiles from polarization lidar

    NASA Astrophysics Data System (ADS)

    Mamouri, Rodanthi-Elisavet; Nisantzi, Argyro; Hadjimitsis, Diofantos; Ansmann, Albert

    2015-04-01

    This paper presents a methodology based on the use of active remote sensing techniques for the estimation of ice nuclei concentrations (INC) for desert dust plumes. Although this method can be applied to other aerosol components, in this study we focus on desert dust. The method makes use of the polarization lidar technique for the separation of dust and non-dust contributions to the particle backscatter and extinction coefficients. The profile of the dust extinction coefficient is converted to APC280 (dust particles with radius larger than 280 nm) and, in a second step, APC280 is converted to INC by means of an APC-INC relationship from the literature. The observed close relationship between dust extinction at 500 nm and APC280 is the key to a successful INC retrieval. The correlation between dust extinction coefficient and APC280 is studied by means of AERONET sun/sky photometer at Morocco, Cape Verde, Barbados, and Cyprus, during situations dominated by desert dust outbreaks. In the present study, polarization lidar observations of the EARLINET (European Aerosol Research Lidar Network) lidar at the Cyprus University of Technology (CUT), Limassol (34.7o N, 33o E), Cyprus were used together with spaceborne lidar observations during CALIPSO satellite overpasses to demonstrate the potential of the new INC retrieval method. A good agreement between the CALIOP (Cloud Aerosol Lidar with Orthogonal Polarization) and our CUT lidar observations regarding the retrieval of dust extinction coefficient, APC280, and INC profiles were found and corroborate the potential of CALIOP to provide 3-D global desert-dust-related INC data sets. In the next step, efforts should be undertaken towards the establishment of a global, height-resolved INC climatology for desert dust plumes. Realistic global INC distributions are required for an improved estimation of aerosol effects on cloud formation and the better quantification of the indirect aerosol effect on climate. Acknowledgements

  15. Relations Between Cloud Condensation Nuclei And Aerosol Optical Properties Relevant to Remote Sensing: Airborne Measurements in Biomass Burning, Pollution and Dust Aerosol Over North America

    NASA Astrophysics Data System (ADS)

    Shinozuka, Y.; Clarke, A.; Howell, S.; Kapustin, V.; McNaughton, C.; Zhou, J.; Decarlo, P.; Jimenez, J.; Roberts, G.; Tomlinson, J.; Collins, D.

    2008-12-01

    Remote sensing of the concentration of cloud condensation nuclei (CCN) would help investigate the indirect effect of tropospheric aerosols on clouds and climate. In order to assess its feasibility, this paper evaluates the spectral-based retrieval technique for aerosol number and seeks one for aerosol solubility, using in-situ aircraft measurements of aerosol size distribution, chemical composition, hygroscopicity, CCN activity and optical properties. Our statistical analysis reveals that the CCN concentration over Mexico can be optically determined to a relative error of <20%, smaller than that for the mainland US and the surrounding oceans (~a factor of 2). Mexico's advantage is four-fold. Firstly, many particles originating from the lightly regulated industrial combustion and biomass burning are large enough to significantly affect light extinction, elevating the correlation between extinction and CCN number in absence of substantial dust. Secondly, the generally low ambient humidity near the major aerosol sources limits the error in the estimated response of particle extinction to humidity changes. Thirdly, because many CCN contain black carbon, light absorption also provides a measure of the CCN concentration. Fourthly, the organic fraction of volatile mass of submicron particles (OMF) is anti-correlated with the wavelength dependence of extinction due to preferential anion uptake by coarse dust, which provides a potential tool for remote-sensing OMF and the particle solubility.

  16. Comparison of Aerosol Single Scattering Albedos Derived by Diverse Techniques In Two North Atlantic Experiments

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Redemann, J.; Schmid, B.; Bergstrom, R. W.; Livingston, J. M.; McIntosh, D. M.; Ramirez, S. A.; Hartley, S.; Hobbs, P. V.; Quinn, P. K.

    2002-01-01

    Aerosol single scattering albedo omega (the ratio of scattering to extinction) is important in determining aerosol climatic effects, in explaining relationships between calculated and measured radiative fluxes, and in retrieving aerosol optical depths from satellite radiances. Recently, two experiments in the North Atlantic region, the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the Second Aerosol Characterization Experiment (ACE-2), determined aerosol omega by a variety of techniques. The techniques included fitting of calculated to measured radiative fluxes; retrievals of omega from skylight radiances; best fits of complex refractive index to profiles of backscatter extinction, and size distribution; and in situ measurements of scattering and absorption at the surface and aloft. Both TARFOX and ACE-2 found a fairly wide range of values for omega at midvisable wavelengths approx. 550 nm, with omega(sub midvis) greater than or equal to 0.85 and less than or equal to 0.99 for the marine aerosol impacted by continental pollution. Frequency distributions of omega could usually be approximated by lognormals in omega(sub max) - omega, with some occurrence of bimodality, suggesting the influence of different aerosol sources or processing. In both TARFOX and ACE-2, closure tests between measured and calculated radiative fluxes yielded best-fit values of omega(sub midvis) 0.90 +/- 0.04 for the polluted boundary layer. Although these results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and other uncertainties (e.g., thermal offsets, unknown gas absorption) The other techniques gave larger values for omega(sub midvis) for the polluted boundary layer, with a typical result of omega(sub midvis) = 0.95 +/- 0.04. Current uncertainties in omega are large in terms of climate effects More tests are needed of the consistency among different methods and of

  17. Assessment of Aerosol Distributions from GEOS-5 Using the CALIPSO Feature Mask

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth

    2010-01-01

    A-train sensors such as MODIS, MISR, and CALIPSO are used to determine aerosol properties, and in the process a means of estimating aerosol type (e.g. smoke vs. dust). Correct classification of aerosol type is important for climate assessment, air quality applications, and for comparisons and analysis with aerosol transport models. The Aerosols-Clouds-Ecosystems (ACE) satellite mission proposed in the NRC Decadal Survey describes a next generation aerosol and cloud suite similar to the current A-train, including a lidar. The future ACE lidar must be able to determine aerosol type effectively in conjunction with modeling activities to achieve ACE objectives. Here we examine the current capabilities of CALIPSO and the NASA Goddard Earth Observing System general circulation model and data assimilation system (GEOS-5), to place future ACE needs in context. The CALIPSO level 2 feature mask includes vertical profiles of aerosol layers classified by type. GEOS-5 provides global 3D aerosol mass for sulfate, sea salt, dust, and black and organic carbon. A GEOS aerosol scene classification algorithm has been developed to provide estimates of aerosol mixtures and extinction profiles along the CALIPSO orbit track. In previous work, initial comparisons between GEOS-5 derived aerosol mixtures and CALIPSO derived aerosol types were presented for July 2007. In general, the results showed that model and lidar derived aerosol types did not agree well in the boundary layer. Agreement was poor over Europe, where CALIPSO indicated the presence of dust and pollution mixtures yet GEOS-5 was dominated by pollution with little dust. Over the ocean in the tropics, the model appeared to contain less sea salt than detected by CALIPSO, yet at high latitudes the situation was reserved. Agreement between CALIPSO and GEOS-5, aerosol types improved above the boundary layer, primarily in dust and smoke dominated regions. At higher altitudes (> 5 km), the model contained aerosol layers not detected

  18. High Spectral Resolution Lidar and MPLNET Micro Pulse Lidar Aerosol Optical Property Retrieval Intercomparison During the 2012 7-SEAS Field Campaign at Singapore

    NASA Technical Reports Server (NTRS)

    Lolli, Simone; Welton, Ellsworth J.; Campbell, James R.; Eloranta, Edwin; Holben, Brent N.; Chew, Boon Ning; Salinas, Santo V.

    2014-01-01

    From August 2012 to February 2013 a High Resolution Spectral Lidar (HSRL; 532 nm) was deployed at that National University of Singapore near a NASA Micro Pulse Lidar NETwork (MPLNET; 527 nm) site. A primary objective of the MPLNET lidar project is the production and dissemination of reliable Level 1 measurements and Level 2 retrieval products. This paper characterizes and quantifies error in Level 2 aerosol optical property retrievals conducted through inversion techniques that derive backscattering and extinction coefficients from MPLNET elastic single-wavelength datasets. MPLNET Level 2 retrievals for aerosol optical depth and extinction/backscatter coefficient profiles are compared with corresponding HSRL datasets, for which the instrument collects direct measurements of each using a unique optical configuration that segregates aerosol and cloud backscattered signal from molecular signal. The intercomparison is performed, and error matrices reported, for lower (0-5km) and the upper (>5km) troposphere, respectively, to distinguish uncertainties observed within and above the MPLNET instrument optical overlap regime.

  19. Determination of accurate vertical atmospheric profiles of extinction and turbulence

    NASA Astrophysics Data System (ADS)

    Hammel, Steve; Campbell, James; Hallenborg, Eric

    2017-09-01

    Our ability to generate an accurate vertical profile characterizing the atmosphere from the surface to a point above the boundary layer top is quite rudimentary. The region from a land or sea surface to an altitude of 3000 meters is dynamic and particularly important to the performance of many active optical systems. Accurate and agile instruments are necessary to provide measurements in various conditions, and models are needed to provide the framework and predictive capability necessary for system design and optimization. We introduce some of the path characterization instruments and describe the first work to calibrate and validate them. Along with a verification of measurement accuracy, the tests must also establish each instruments performance envelope. Measurement of these profiles in the field is a problem, and we will present a discussion of recent field test activity to address this issue. The Comprehensive Atmospheric Boundary Layer Extinction/Turbulence Resolution Analysis eXperiment (CABLE/TRAX) was conducted late June 2017. There were two distinct objectives for the experiment: 1) a comparison test of various scintillometers and transmissometers on a homogeneous horizontal path; 2) a vertical profile experiment. In this paper we discuss only the vertical profiling effort, and we describe the instruments that generated data for vertical profiles of absorption, scattering, and turbulence. These three profiles are the core requirements for an accurate assessment of laser beam propagation.

  20. Coordinated Airborne, Spaceborne and Ground-based Measurements of Massive Thick Aerosol Layers during the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J. R.; Torres, O.

    2003-01-01

    During the dry season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), coordinated observations were made of massive thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sun photometer measurements of aerosol optical depth (lambda = 0.354- 1.557 microns), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data (MPL-Net), and with measurements from a downward pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths fiom the Sun photometer and those retrieved over land and over water using four spaceborne sensors (TOMS, MODIS, MISR, and ATSR-2).

  1. Comparison of Aerosol Single Scattering Albedos Derived By Diverse Techniques in Two North Atlantic Experiments

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Redemann, J.; Schmid, B.; Bergstrom, R. W.; Livingston, J. M.; McIntosh, D. M.; Hartley, S.; Hobbs, P. V.; Quinn, P. K.; Carrico, C. M.; hide

    2000-01-01

    Aerosol single scattering albedo w (the ratio of scattering to extinction) is important in determining aerosol climatic effects, in explaining relationships between calculated and measured radiative fluxes, and in retrieving aerosol optical depths from satellite radiances. Recently, two experiments in the North Atlantic region, TARFOX and ACE-2, determined aerosol w by a variety of techniques. The techniques included fitting of calculated to measured fluxes; retrievals of w from skylight radiances; best fits of complex refractive index to profiles of backscatter, extinction, and size distribution; and in situ measurements of scattering and absorption at the surface and aloft. Both TARFOX and ACE-2 found a fairly wide range of values for w at midvisible wavelengths, with 0.85 less than wmidvis less than 0.99 for the marine aerosol impacted by continental pollution. Frequency distributions of w could usually be approximated by lognormals in wmax-w, with some occurrence of bimodality, suggesting the influence of different aerosol sources or processing. In both TARFOX and ACE-2, closure tests between measured and calculated radiative fluxes yielded best-fit values of wmidvis of 0.90+/-0.04 for the polluted boundary layer. Although these results have the virtue of describing the column aerosol unperturbed by sampling, they are subject to questions about representativeness and possible artifacts (e.g., unknown gas absorption). The other techniques gave larger values for wmidvis for the polluted boundary layer, with a typical result of wmidvis = 0.95+/-0.04, Current uncertainties in vv are large in terms of climate effects. More tests are needed of the consistency among different methods and of humidification effects on w.

  2. Doppler Lidar Measurements of Tropospheric Wind Profiles Using the Aerosol Double Edge Technique

    NASA Technical Reports Server (NTRS)

    Gentry, Bruce M.; Li, Steven X.; Mathur, Savyasachee; Korb, C. Laurence; Chen, Huailin

    2000-01-01

    The development of a ground based direct detection Doppler lidar based on the recently described aerosol double edge technique is reported. A pulsed, injection seeded Nd:YAG laser operating at 1064 nm is used to make range resolved measurements of atmospheric winds in the free troposphere. The wind measurements are determined by measuring the Doppler shift of the laser signal backscattered from atmospheric aerosols. The lidar instrument and double edge method are described and initial tropospheric wind profile measurements are presented. Wind profiles are reported for both day and night operation. The measurements extend to altitudes as high as 14 km and are compared to rawinsonde wind profile data from Dulles airport in Virginia. Vertical resolution of the lidar measurements is 330 m and the rms precision of the measurements is a low as 0.6 m/s.

  3. Typical tropospheric aerosol backscatter profiles for Southern Ireland: The Cork Raman lidar

    NASA Astrophysics Data System (ADS)

    McAuliffe, Michael A. P.; Ruth, Albert A.

    2013-02-01

    A Raman lidar instrument (UCLID) was established at the University College Cork as part of the European lidar network EARLINET. Raman backscatter coefficients, extinction coefficients and lidar ratios were measured within the period 28/08/2010 and 24/04/2011. Typical atmospheric scenarios over Southern Ireland in terms of the aerosol load in the planetary boundary layer are outlined. The lidar ratios found are typical for marine atmospheric condition (lidar ratio ca. 20-25 sr). The height of the planetary boundary layer is below 1000 m and therefore low in comparison to heights found at other lidar sites in Europe. On the 21st of April a large aerosol load was detected, which was assigned to a Saharan dust event based on HYSPLIT trajectories and DREAM forecasts along with the lidar ratio (70 sr) for the period concerned. The dust was found at two heights, pure dust at 2.5 km and dust mixing with pollution from 0.7 to 1.8 km with a lidar ratio of 40-50 sr.

  4. ACCURATE: Influence of Cloud Layers and Aerosol on Infrared Laser Occultation Signals for Sensing of Greenhouse Gases

    NASA Astrophysics Data System (ADS)

    Proschek, V.; Schweitzer, S.; Emde, C.; Ladstädter, F.; Fritzer, J.; Kirchengast, G.

    2009-04-01

    ACCURATE (Atmospheric Climate and Chemistry in the UTLS Region And climate Trends Explorer), a new climate satellite concept, enables simultaneous measurement of profiles of greenhouse gases, isotopes, wind and thermodynamic variables from Low Earth Orbit (LEO) satellites. The measurement principle applied is a combination of the novel LEO-LEO infrared laser occultation (LIO) technique and the well-studied but not yet flown LEO-LEO microwave occultation (LMO) technique. As intrinsic to the space-borne occultation technique, the measurements are evenly distributed around the world, have high vertical resolution and high accuracy and are stable over long time periods. The LIO uses near-monochromatic signals in the short-wave infrared range (~2-2.5 m in the case of ACCURATE) which are absorbed by various trace species in the Earth's atmosphere. From signal transmission measurements, profiles of the concentration of the absorbing species can be derived given that temperature and pressure are accurately known from LMO. The current ACCURATE mission design is arranged for the measurement of six greenhouse gases (H2O, CO2, CH4, N2O, O3, CO) and four isotopes (13CO2, C18OO, HDO, H218O) with focus on the upper troposphere/lower stratosphere region (UTLS, 5-35 km). Wind speed in line-of-sight can be derived from a line-symmetric transmission difference which is caused by wind-induced Doppler shift. By-products are information on cloud layering, aerosol extinction and scintillation strength. This contribution presents an overview on the ACCURATE mission design and the expected accuracy of retrieved atmospheric variables and further focuses on the influence of clouds and aerosols on propagating LIO signals. Special emphasis will be given to sub-visible cirrus clouds which are semi-transparent to infrared signals. A simple frequency dependent cloud extinction parametrization was included into the occultation propagation software EGOPS and evaluated against results of the

  5. The GAW Aerosol Lidar Observation Network (GALION) as a source of near-real time aerosol profile data for model evaluation and assimilation

    NASA Astrophysics Data System (ADS)

    Hoff, R. M.; Pappalardo, G.

    2010-12-01

    In 2007, the WMO Global Atmospheric Watch’s Science Advisory Group on Aerosols described a global network of lidar networks called GAW Aerosol Lidar Observation Network (GALION). GALION has a purpose of providing expanded coverage of aerosol observations for climate and air quality use. Comprised of networks in Asia (AD-NET), Europe (EARLINET and CIS-LINET), North America (CREST and CORALNET), South America (ALINE) and with contribution from global networks such as MPLNET and NDACC, the collaboration provides a unique capability to define aerosol profiles in the vertical. GALION is designed to supplement existing ground-based and column profiling (AERONET, PHOTONS, SKYNET, GAWPFR) stations. In September 2010, GALION held its second workshop and one component of discussion focussed how the network would integrate into model needs. GALION partners have contributed to the Sand and Dust Storm Warning and Analysis System (SDS-WAS) and to assimilation in models such as DREAM. This paper will present the conclusions of those discussions and how these observations can fit into a global model analysis framework. Questions of availability, latency, and aerosol parameters that might be ingested into models will be discussed. An example of where EARLINET and GALION have contributed in near-real time observations was the suite of measurements during the Eyjafjallajokull eruption in Iceland and its impact on European air travel. Lessons learned from this experience will be discussed.

  6. Applications of broadband cavity enhanced spectroscopy for measurements of trace gases and aerosols

    NASA Astrophysics Data System (ADS)

    Washenfelder, R. A.; Attwood, A. R.; Brock, C. A.; Brown, S. S.; Dube, W. P.; Flores, J. M.; Langford, A. O.; Min, K. E.; Rudich, Y.; Stutz, J.; Wagner, N.; Young, C.; Zarzana, K. J.

    2015-12-01

    Broadband cavity enhanced spectroscopy (BBCES) uses a broadband light source, optical cavity, and multichannel detector to measure light extinction with high sensitivity. This method differs from cavity ringdown spectroscopy, because it uses an inexpensive, incoherent light source and allows optical extinction to be determined simultaneously across a broad wavelength region.Spectral fitting methods can be used to retrieve multiple absorbers across the observed wavelength region. We have successfully used this method to measure glyoxal (CHOCHO), nitrous acid (HONO), and nitrogen dioxide (NO2) from ground-based and aircraft-based sampling platforms. The detection limit (2-sigma) in 5 s for retrievals of CHOCHO, HONO and NO2 is 32, 250 and 80 parts per trillion (pptv).Alternatively, gas-phase absorbers can be chemically removed to allow the accurate determination of aerosol extinction. In the laboratory, we have used the aerosol extinction measurements to determine scattering and absorption as a function of wavelength. We have deployed a ground-based field instrument to measure aerosol extinction, with a detection limit of approximately 0.2 Mm-1 in 1 min.BBCES methods are most widely used in the near-ultraviolet and visible spectral region. Recently, we have demonstrated measurements at 315-350 nm for formaldehyde (CH2O) and NO2. Extending the technique further into the ultraviolet spectral region will allow important additional measurements of trace gas species and aerosol extinction.

  7. Aerosol profiling during the large scale field campaign CINDI-2

    NASA Astrophysics Data System (ADS)

    Apituley, Arnoud; Roozendael, Michel Van; Richter, Andreas; Wagner, Thomas; Friess, Udo; Hendrick, Francois; Kreher, Karin; Tirpitz, Jan-Lukas

    2018-04-01

    For the validation of space borne observations of NO2 and other trace gases from hyperspectral imagers, ground based instruments based on the MAXDOAS technique are an excellent choice, since they rely on similar retrieval techniques as the observations from orbit. To ensure proper traceability of the MAXDOAS observations, a thorough validation and intercomparison is mandatory. Advanced MAXDOAS observation and retrieval techniques enable inferring vertical structure of trace gases and aerosols. These techniques and their results need validation by e.g. lidar techniques. For the proper understanding of the results from passive remote sensing techniques, independent observations are needed that include parameters needed to understand the light paths, i.e. in-situ aerosol observations of optical and microphysical properties, and essential are in particular the vertical profiles of aerosol optical properties by (Raman) lidar. The approach used in the CINDI-2 campaign held in Cabauw in 2016 is presented in this paper and the results will be discussed in the presentation at the conference.

  8. Measurement and Modeling of Vertically Resolved Aerosol Optical Properties and Radiative Fluxes Over the ARM SGP Site

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Arnott, P.; Bucholtz, A.; Colarco, P.; Covert, D.; Eilers, J.; Elleman, R.; Ferrare, R.; Flagan, R.; Jonsson, H.

    2003-01-01

    In order to meet one of its goals - to relate observations of radiative fluxes and radiances to the atmospheric composition - the Department of Energy's Atmospheric Radiation Measurement (ARM) program has pursued measurements and modeling activities that attempt to determine how aerosols impact atmospheric radiative transfer, both directly and indirectly. However, significant discrepancies between aerosol properties measured in situ or remotely remain. One of the objectives of the Aerosol Intensive Operational Period (TOP) conducted by ARM in May 2003 at the ARM Southern Great Plains (SGP) site in north central Oklahoma was to examine and hopefully reduce these differences. The IOP involved airborne measurements from two airplanes over the heavily instrumented SGP site. We give an overview of airborne results obtained aboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter aircraft. The Twin Otter performed 16 research flights over the SGP site. The aircraft carried instrumentation to perform in-situ measurements of aerosol absorption, scattering, extinction and particle size. This included such novel techniques as the photoacoustic and cavity ring-down methods for in-situ absorption (675 nm) and extinction (675 and 1550 nm) and a new multiwavelength, filter-based absorption photometer (467, 530, 660 nm). A newly developed instrument measured cloud condensation nucleus concentration (CCN) concentrations at two supersaturation levels. Aerosol optical depth and extinction (354-2139 nm) were measured with the NASA Ames Airborne Tracking 14-channel sunphotometer. Furthermore, up-and downwelling solar (broadband and spectral) and infrared radiation were measured using seven individual radiometers. Three up-looking radiometers werer mounted on a newly developed stabilized platform, keeping the instruments level up to aircraft pitch and roll angles of approximately 10(exp 0). This resulted in unprecedented continuous vertical profiles

  9. SAGE II Measurements of Stratospheric Aerosol Properties at Non-Volcanic Levels

    NASA Technical Reports Server (NTRS)

    Thomason, Larry W.; Burton, Sharon P.; Luo, Bei-Ping; Peter, Thomas

    2008-01-01

    Since 2000, stratospheric aerosol levels have been relatively stable and at the lowest levels observed in the historical record. Given the challenges of making satellite measurements of aerosol properties at these levels, we have performed a study of the sensitivity of the product to the major components of the processing algorithm used in the production of SAGE II aerosol extinction measurements and the retrieval process that produces the operational surface area density (SAD) product. We find that the aerosol extinction measurements, particularly at 1020 nm, remain robust and reliable at the observed aerosol levels. On the other hand, during background periods, the SAD operational product has an uncertainty of at least a factor of 2 during due to the lack of sensitivity to particles with radii less than 100 nm.

  10. Wintertime characteristics of aerosols over middle Indo-Gangetic Plain: Vertical profile, transport and radiative forcing

    NASA Astrophysics Data System (ADS)

    Kumar, M.; Raju, M. P.; Singh, R. K.; Singh, A. K.; Singh, R. S.; Banerjee, T.

    2017-01-01

    Winter-specific characteristics of airborne particulates over middle Indo-Gangetic Plain (IGP) were evaluated in terms of aerosol chemical and micro-physical properties under three-dimensional domain. Emphases were made for the first time to identify intra-seasonal variations of aerosols sources, horizontal and vertical transport, effects of regional meteorology and estimating composite aerosol short-wave radiative forcing over an urban region (25°10‧-25°19‧N; 82°54‧-83°4‧E) at middle-IGP. Space-borne passive (Aqua and Terra MODIS, Aura OMI) and active sensor (CALIPSO-CALIOP) based observations were concurrently used with ground based aerosol mass measurement for entire winter and pre-summer months (December, 1, 2014 to March, 31, 2015). Exceptionally high aerosol mass loading was recorded for both PM10 (267.6 ± 107.0 μg m- 3) and PM2.5 (150.2 ± 89.4 μg m- 3) typically exceeding national standard. Aerosol type was mostly dominated by fine particulates (particulate ratio: 0.61) during pre to mid-winter episodes before being converted to mixed aerosol types (ratio: 0.41-0.53). Time series analysis of aerosols mass typically identified three dissimilar aerosol loading episodes with varying attributes, well resemble to that of previous year's observation representing its persisting nature. Black carbon (9.4 ± 3.7 μg m- 3) was found to constitute significant proportion of fine particulates (2-27%) with a strong diurnal profile. Secondary inorganic ions also accounted a fraction of particulates (PM2.5: 22.5%; PM10: 26.9%) having SO4- 2, NO3- and NH4+ constituting major proportion. Satellite retrieved MODIS-AOD (0.01-2.30) and fine mode fractions (FMF: 0.01-1.00) identified intra-seasonal variation with transport of aerosols from upper to middle-IGP through continental westerly. Varying statistical association of columnar and surface aerosol loading both in terms of fine (r; PM2.5: MODIS-AOD: 0.51) and coarse particulates (PM10: MODIS-AOD: 0.53) was

  11. The potential of LIRIC to validate the vertical profiles of the aerosol mass concentration estimated by an air quality model

    NASA Astrophysics Data System (ADS)

    Siomos, Nikolaos; Filoglou, Maria; Poupkou, Anastasia; Liora, Natalia; Dimopoulos, Spyros; Melas, Dimitris; Chaikovsky, Anatoli; Balis, Dimitris

    2015-04-01

    Vertical profiles of the aerosol mass concentration derived by a retrieval algorithm that uses combined sunphotometer and LIDAR data (LIRIC) were used in order to validate the mass concentration profiles estimated by the air quality model CAMx. LIDAR and CIMEL measurements of the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki were used for this validation.The aerosol mass concentration profiles of the fine and coarse mode derived by CAMx were compared with the respective profiles derived by the retrieval algorithm. For the coarse mode particles, forecasts of the Saharan dust transportation model BSC-DREAM8bV2 were also taken into account. Each of the retrieval algorithm's profiles were matched to the models' profile with the best agreement within a time window of four hours before and after the central measurement. OPAC, a software than can provide optical properties of aerosol mixtures, was also employed in order to calculate the angstrom exponent and the lidar ratio values for 355nm and 532nm for each of the model's profiles aiming in a comparison with the angstrom exponent and the lidar ratio values derived by the retrieval algorithm for each measurement. The comparisons between the fine mode aerosol concentration profiles resulted in a good agreement between CAMx and the retrieval algorithm, with the vertical mean bias error never exceeding 7 μgr/m3. Concerning the aerosol coarse mode concentration profiles both CAMx and BSC-DREAM8bV2 values are severely underestimated, although, in cases of Saharan dust transportation events there is an agreement between the profiles of BSC-DREAM8bV2 model and the retrieval algorithm.

  12. A Combined Retrieval of Aerosol Microphysical Properties using active HSRL and Passive Polarimeter Multi-sensor Data

    NASA Astrophysics Data System (ADS)

    Liu, X.; Stamnes, S.; Ferrare, R. A.; Hostetler, C. A.; Burton, A. S.; Chemyakin, E.; Sawamura, P.; Mueller, D.

    2017-12-01

    Vertically resolved measurements of aerosol optical, microphysical, and macrophysical parameters are required to better understand the influence of aerosols on climate and air quality. We will describe an Optimal Estimation (OE) retrieval framework which can perform aerosol property retrievals in three modes: 1) lidar-only, 2) polarimeter-only, and 3) combined lidar-polarimeter muti-sensor system. The lidar data can be profile measurements by any high spectral resolution lidar (HSRL) and/or Raman lidar with multiple wavelengths of aerosol backscattering (β) and extinction (α). The polarimeter data can be any multi-angle and multi-wavelength measurements with 2 or 3 polarization components. We will show aerosol microphysical retrieval results from the HSRL-2 data measured from various NASA airborne field campaigns including the recent ORACLES mission. We will also show the OE retrieval results from the polarimeter-only mode. Finally, we will demonstrate how the information content of the aerosol microphysical retrieval is increased by combining the active HSRL and passive polarimeter data in our simultaneous OE retrieval system.

  13. The Effect of Aerosol on Gravity Wave Characteristics above the Boundary Layer over a Tropical Location

    NASA Astrophysics Data System (ADS)

    Rakshit, G.; Jana, S.; Maitra, A.

    2017-12-01

    The perturbations of temperature profile over a location give an estimate of the potential energy of gravity waves propagating through the atmosphere. Disturbances in the lower atmosphere due to tropical deep convection, orographic effects and various atmospheric disturbances generates of gravity waves. The present study investigates the gravity wave energy estimated from fluctuations in temperature profiles over the tropical location Kolkata (22°34' N, 88°22' E). Gravity waves are most intense during the pre-monsoon period (March-June) at the present location, the potential energy having high values above the boundary layer (2-4 km) as observed from radiosonde profiles. An increase in temperature perturbation, due to high ambient temperature in the presence of heat absorbing aerosols, causes an enhancement in potential energy. As the present study location is an urban metropolitan city experiencing high level of pollution, pollutant aerosols can go much above the normal boundary layer during daytime due to convection causing an extended boundary layer. The Aerosol Index (AAI) obtained from Global Ozone Monitoring Experiment-2 (GOME-2) on MetOp-A platform at 340 nm and 380 nm confirms the presence of absorbing aerosol particles over the present location. The Hysplit back trajectory analysis shows that the aerosol particles at those heights are of local origin and are responsible for depleting liquid water content due to cloud burning. The aerosol extinction coefficient obtained from CALIPSO data exhibits an increasing trend during 2006-2016 accompanied by a similar pattern of gravity wave energy. Thus the absorbing aerosols have a significant role in increasing the potential energy of gravity wave at an urban location in the tropical region.

  14. The Influence of Chemical Composition and Relative Humidity on the Optical Properties of Aerosols During the Southern Oxidant and Aerosol Study (SOAS)

    NASA Astrophysics Data System (ADS)

    Attwood, A. R.; Washenfelder, R. A.; Brock, C. A.; Brown, S. S.; Hu, W.; Campuzano Jost, P.; Day, D. A.; Palm, B. B.; Simoes de Sa, S.; Jimenez, J. L.

    2013-12-01

    Atmospheric particles are produced from a wide variety of both anthropogenic and natural sources and play an important role in the Earth's radiative budget by direct scattering and absorption of radiation. To address this impact, in situ measurements of aerosol optical, chemical and hygroscopic properties were performed during the Southern Oxidant and Aerosol Study (SOAS), which took place in the summer of 2013. Ground based measurements of sub-micron aerosol in the southeastern United States were made to investigate the influence of chemical composition and hygroscopicity on aerosol optical properties. We report the wavelength dependence of aerosol extinction cross sections measured with a novel broadband cavity enhanced spectrometer covering a wavelength range of 360-420 nm using two light emitting diodes (LED) and a separate cavity ring down (CRDS) channel. The sensitivity of the relative humidity dependence of extinction based on the type of aerosol present is examined and we show that the optical properties and hygroscopicity of aerosols are greatly influenced by the fraction of sulfate and organics within the particles. Additional data analysis from the SOAS campaign will be presented. The results, thus far, illustrate that the variability in aerosol chemical composition can impact visibility and climate forcing in this region.

  15. Chemical apportionment of aerosol optical properties during the Asia-Pacific Economic Cooperation summit in Beijing, China

    NASA Astrophysics Data System (ADS)

    Han, Tingting; Xu, Weiqi; Chen, Chen; Liu, Xingang; Wang, Qingqing; Li, Jie; Zhao, Xiujuan; Du, Wei; Wang, Zifa; Sun, Yele

    2015-12-01

    We have investigated the chemical and optical properties of aerosol particles during the 2014 Asia-Pacific Economic Cooperation (APEC) summit in Beijing, China, using the highly time-resolved measurements by a high-resolution aerosol mass spectrometer and a cavity attenuated phase shift extinction monitor. The average (±σ) extinction coefficient (bext) and absorption coefficient (bap) were 186.5 (±184.5) M m-1 and 23.3 (±21.9) M m-1 during APEC, which were decreased by 63% and 56%, respectively, compared to those before APEC primarily due to strict emission controls. The aerosol composition and size distributions showed substantial changes during APEC; as a response, the mass scattering efficiency (MSE) of PM1 was decreased from 4.7 m2 g-1 to 3.5 m2 g-1. Comparatively, the average single-scattering albedo (SSA) remained relatively unchanged, illustrating the synchronous reductions of bext and bap during APEC. MSE and SSA were found to increase as function of the oxidation degree of organic aerosol (OA), indicating a change of aerosol optical properties during the aging processes. The empirical relationships between chemical composition and particle extinction were established using a multiple linear regression model. Our results showed the largest contribution of ammonium nitrate to particle extinction, accounting for 35.1% and 29.3% before and during APEC, respectively. This result highlights the important role of ammonium nitrate in the formation of severe haze pollution during this study period. We also observed very different optical properties of primary and secondary aerosol. Owing to emission controls in Beijing and surrounding regions and also partly the influences of meteorological changes, the average bext of secondary aerosol during APEC was decreased by 71% from 372.3 M m-1 to 108.5 M m-1, whereas that of primary aerosol mainly from cooking, traffic, and biomass burning emissions showed a smaller reduction from 136.7 M m-1 to 71.3 M m-1. As a result

  16. Column Closure Studies of Lower Tropospheric Aerosol and Water Vapor During ACE-Asia Using Airborne Sunphotometer, Airborne In-Situ and Ship-Based Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Hegg, A.; Wang, J.; Bates, D.; Redemann, J.; Russells, P. B.; Livingston, J. M.; Jonsson, H. H.; Welton, E. J.; Seinfield, J. H.

    2003-01-01

    We assess the consistency (closure) between solar beam attenuation by aerosols and water vapor measured by airborne sunphotometry and derived from airborne in-situ, and ship-based lidar measurements during the April 2001 Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia). The airborne data presented here were obtained aboard the Twin Otter aircraft. Comparing aerosol extinction o(550 nm) from four different techniques shows good agreement for the vertical distribution of aerosol layers. However, the level of agreement in absolute magnitude of the derived aerosol extinction varied among the aerosol layers sampled. The sigma(550 nm) computed from airborne in-situ size distribution and composition measurements shows good agreement with airborne sunphotometry in the marine boundary layer but is considerably lower in layers dominated by dust if the particles are assumed to be spherical. The sigma(550 nm) from airborne in-situ scattering and absorption measurements are about approx. 13% lower than those obtained from airborne sunphotometry during 14 vertical profiles. Combining lidar and the airborne sunphotometer measurements reveals the prevalence of dust layers at altitudes up to 10 km with layer aerosol optical depth (from 3.5 to 10 km altitude) of approx. 0.1 to 0.2 (500 nm) and extinction-to-backscatter ratios of 59-71 sr (523 nm). The airborne sunphotometer aboard the Twin Otter reveals a relatively dry atmosphere during ACE- Asia with all water vapor columns less than 1.5 cm and water vapor densities w less than 12 g/cu m. Comparing layer water vapor amounts and w from the airborne sunphotometer to the same quantities measured with aircraft in-situ sensors leads to a high correlation (r(sup 3)=0.96) but the sunphotometer tends to underestimate w by 7%.

  17. Optimal Aerosol Parameterization for Remote Sensing Retrievals

    NASA Technical Reports Server (NTRS)

    Newchurch, Michael J.

    2004-01-01

    We have developed a new algorithm for the retrieval of aerosol and gases from SAGE It1 solar transmission measurements. This algorithm improves upon the NASA operational algorithm in several key aspects, including solving the problem non-linearly and incorporating a new methodology for separating the contribution of aerosols and gases. In order to extract aerosol information we have built a huge database of aerosol models for both stratospheric and tropospheric aerosols, and polar stratospheric cloud particles. This set of models allows us to calculate a vast range of possible extinction spectra for aerosols. and from these, derive a set of eigenvectors which then provide the basis set used in our inversion algorithm. Our aerosol algorithm and retrievals are described in several articles (listed in References Section) published under this grant. In particular they allow us to analyze the spectral properties of aerosols and PSCs and ultimately derive their microphysical properties. We have found some considerable differences between our spectra and the ones derived from the SAGE III operational algorithm. These are interesting as they provide an independent check on the validity of published aerosol data and, in particular, on their associated uncertainties. In order to understand these differences, we are assembling independent aerosol data from other sources with which to make comparisons. We have carried out extensive comparisons of our ozone retrievals with both SAGE III and independent lidar, ozonesonde, and satellite measurements (Polyakov et al., 2004). These show very good agreement throughout the stratosphere and help to quantify differences which can be attributed to natural variation in ozone versus that produced by algorithmic differences. In the mid - upper stratosphere, agreement with independent data was generally within 5 - 20%. but in the lower stratosphere the differences were considerably larger. We believe that a large proportion of this

  18. Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM): VOLCANIC AEROSOLS DERIVED FROM EMISSIONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mills, Michael J.; Schmidt, Anja; Easter, Richard

    Accurate representation of global stratospheric aerosol properties from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-loss enhancements of recent volcanic activity. Attribution of climate and ozone variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the apparent rate of global average temperature increases, and variable recovery of the Antarctic ozone hole. We have developed a climatology of global aerosol properties from 1990 to 2014 calculated based on volcanic and non-volcanic emissions of sulfur sources. We have complied a database of volcanic SO2 emissions and plume altitudes for eruptionsmore » between 1990 and 2014, and a new prognostic capability for simulating stratospheric sulfate aerosols in version 5 of the Whole Atmosphere Community Climate Model, a component of the Community Earth System Model. Our climatology shows remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD climatology represents a significant improvement over satellite-based analyses, which ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD climatology significantly improves on that provided for the Chemistry-Climate Model Initiative, which misses 60% of the SAD measured in situ. Our climatology of aerosol properties is publicly available on the Earth System Grid.« less

  19. Determination of the particulate extinction-coefficient profile and the column-integrated lidar ratios using the backscatter-coefficient and optical-depth profiles

    Treesearch

    Vladimir A Kovalev; Wei Min Hao; Cyle Wold

    2007-01-01

    A new method is considered that can be used for inverting data obtained from a combined elastic-inelastic lidar or a high spectral resolution lidar operating in a one-directional mode, or an elastic lidar operating in a multiangle mode. The particulate extinction coefficient is retrieved from the simultaneously measured profiles of the particulate backscatter...

  20. A new stochastic algorithm for inversion of dust aerosol size distribution

    NASA Astrophysics Data System (ADS)

    Wang, Li; Li, Feng; Yang, Ma-ying

    2015-08-01

    Dust aerosol size distribution is an important source of information about atmospheric aerosols, and it can be determined from multiwavelength extinction measurements. This paper describes a stochastic inverse technique based on artificial bee colony (ABC) algorithm to invert the dust aerosol size distribution by light extinction method. The direct problems for the size distribution of water drop and dust particle, which are the main elements of atmospheric aerosols, are solved by the Mie theory and the Lambert-Beer Law in multispectral region. And then, the parameters of three widely used functions, i.e. the log normal distribution (L-N), the Junge distribution (J-J), and the normal distribution (N-N), which can provide the most useful representation of aerosol size distributions, are inversed by the ABC algorithm in the dependent model. Numerical results show that the ABC algorithm can be successfully applied to recover the aerosol size distribution with high feasibility and reliability even in the presence of random noise.

  1. Vertical Profile of Aerosol Properties at Pico Mountain, Azores

    NASA Astrophysics Data System (ADS)

    Wright, K.; Mazzoleni, C.; Mazzoleni, L. R.; Dzepina, K.; Hueber, J.; China, S.; Sharma, N.

    2013-12-01

    Pico Mountain (2325m asl) is a dormant volcano in the archipelago of the Azores1500 km west of Lisbon, Portugal in the North Atlantic. It differs from typical mountain ranges such as the Alps or the Rockies, which are large and present a complex orography. Pico Mountain has a simple cone-like structure with only one main peak and is thousands of kilometers away from any other significant mountain range. In summer months, it is typical for air masses to move around the mountain rather than traveling up its face. This implies that often the peak of the mountain lies above the marine boundary layer in the free troposphere, while the lower part of the mountain is affected by marine clouds and marine air-masses. An atmospheric monitoring station, the Pico Mountain Observatory was established in 2001 in the summit caldera of the volcano at 2225m above sea level. The observatory is far from large populations or pollution sources, which makes the station ideal to study atmospheric gases and aerosols transported over long-ranges in the free troposphere. The station is reachable only by foot following a steep and strenuous hiking trail. In the summer of 2013 we began to collect vertical profiles of aerosol by carrying an instrumented backpack up to the summit of the mountain, with the goal of studying the vertical structure of atmospheric aerosols from the marine boundary layer to the free troposphere. The backpack was carried from the base of trail at 1200m asl. The backpack was equipped with the following instruments: 1. Nephelometer to measure light scattering from aerosol 2. 2-size optical particle counter (300-500 nm) 3. Portable micro-aethalometer to measure absorbing aerosols 4. SEM/TEM sampler to collect particles for off-line electron microscopy analysis 5. Battery powered data logger to measure relative humidity, temperature and pressure 6. GPS tracking device We provide a preliminary analysis of data collected in 2013 to gain insight on the vertical distribution

  2. Vertical Profiles of Light-Absorbing Aerosol: A Combination of In-situ and AERONET Observations during NASA DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C.; Crumeyrolle, S.; Giles, D. M.; Holben, B. N.; Hudgins, C.; Martin, R.; Moore, R.; Shook, M.; Thornhill, K. L., II; Winstead, E.; Anderson, B. E.

    2014-12-01

    Understanding the vertical profile of atmospheric aerosols plays a vital role in utilizing spaceborne, column-integrated satellite observations. The properties and distribution of light-absorbing aerosol are particularly uncertain despite significant air quality and climate ramifications. Advanced retrieval algorithms are able to derive complex aerosol properties (e.g., wavelength-dependent absorption coefficient and single scattering albedo) from remote-sensing measurements, but quantitative relationships to surface conditions remain a challenge. Highly systematic atmospheric profiling during four unique deployments for the NASA DISCOVER-AQ project (Baltimore, MD, 2011; San Joaquin Valley, CA, 2013; Houston, TX, 2013; Denver, CO, 2014) allow statistical assessment of spatial, temporal, and source-related variability for light-absorbing aerosol properties in these distinct regions. In-situ sampling in conjunction with a dense network of AERONET sensors also allows evaluation of the sensitivity, limitations, and advantages of remote-sensing data products over a wide range of conditions. In-situ aerosol and gas-phase observations were made during DISCOVER-AQ aboard the NASA P-3B aircraft. Aerosol absorption coefficients were measured by a Particle Soot Absorption Photometer (PSAP). Approximately 200 profiles for each of the four deployments were obtained, from the surface (25-300m altitude) to 5 km, and are used to calculate absorption aerosol optical depths (AAODs). These are quantitatively compared to AAOD derived from AERONET Level 1.5 retrievals to 1) explore discrepancies between measurements, 2) quantify the fraction of AAOD that exists directly at the surface and is often missed by airborne sampling, and 3) evaluate the potential for deriving ground-level black carbon (BC) concentrations for air quality prediction. Aerosol size distributions are used to assess absorption contributions from mineral dust, both at the surface and aloft. SP2 (Single Particle Soot

  3. Coordinated Airborne, Spaceborne, and Ground-Based Measurements of Massive, Thick Aerosol Layers During the Dry Season in Southern Africa

    NASA Technical Reports Server (NTRS)

    Schmid, B.; Redemann, J.; Russell, P. B.; Hobbs, P. V.; Hlavka, D. L.; McGill, M. J.; Holben, B. N.; Welton, E. J.; Campbell, J.; Torres, O.; hide

    2002-01-01

    During the dry-season airborne campaign of the Southern African Regional Science Initiative (SAFARI 2000), unique coordinated observations were made of massive, thick aerosol layers. These layers were often dominated by aerosols from biomass burning. We report on airborne Sunphotometer measurements of aerosol optical depth (lambda=354-1558 nm), columnar water vapor, and vertical profiles of aerosol extinction and water vapor density that were obtained aboard the University of Washington's Convair-580 research aircraft. We compare these with ground-based AERONET Sun/sky radiometer results, with ground based lidar data MPL-Net), and with measurements from a downward-pointing lidar aboard the high-flying NASA ER-2 aircraft. Finally, we show comparisons between aerosol optical depths from the Sunphotometer and those retrieved over land and over water using four spaceborne sensors (TOMS (Total Ozone Mapping Spectrometer), MODIS (Moderate Resolution Imaging Spectrometer), MISR (Multiangle Imaging Spectroradiometer) and ATSR-2 (Along Track Scanning Radiometer)).

  4. Broadband optical extinction measurements and complex refractive indices in the ultraviolet spectral region for biogenic secondary organic aerosol exposed to ammonia

    NASA Astrophysics Data System (ADS)

    Flores, J.; Washenfelder, R. A.; Lee, H.; Segev, L.; Nizkorodov, S.; Brown, S. S.; Rudich, Y.

    2013-12-01

    The interaction between aerosols and sunlight plays an important role in the radiative balance of Earth's atmosphere. Aerosols can both scatter and absorb solar radiation causing surface cooling and heating of the atmosphere. These interactions depend on the optical properties of the aerosols (i.e., complex refractive index). Secondary organic aerosol (SOA) account for a significant fraction of the tropospheric aerosol. However, their chemical, physical, and optical properties, especially as they are processed in the atmosphere (aging), are still poorly understood. In this study, SOA formed by the ozonolysis of various biogenic volatile organic compound (BVOC) precursors (α-pinene, limonene, and α-humulene) were exposed to humid air containing various concentrations of gaseous ammonia which has been shown to cause the biogenic SOA to ';brown' on filters. The extent of absorption of the SOA in the aerosol phase cause by the exposure to gaseous ammonia was measured by a newly developed instrument to measure aerosol extinction as a function of wavelength using Broadband Cavity Enhanced Spectroscopy (BBCES) with a broadband light source. Size-selected measurements of the humid SOA exposed to NH3 for about 1.5 hours were used to derive complex refractive indices (RI) as a function of wavelength in the UV spectral region (from 360 - 420nm). The imaginary part of the refractive index did not exceed 0.05 in the 360 - 420 nm range for SOA formed from the three BVOCs even at high concentrations of NH3 (>1ppm), allowing to place an upper limit of k = 0.05. Furthermore, the small k values are consistent with bulk UV-VIS measurements. However, for the α-pinene SOA, the real part of the RI slightly increased from n = 1.49 to n = 1.55 with negligible spectral dependence. For limonene and α-humulene the real part remind constant within error calculations. Based on these observations, reactive uptake of gaseous ammonia is not expected to significantly affect absorption and

  5. Testing the MODIS Satellite Retrieval of Aerosol Fine-Mode Fraction

    NASA Technical Reports Server (NTRS)

    Anderson, Theodore L.; Wu, Yonghua; Chu, D. Allen; Schmid, Beat; Redemann, Jens; Dubovik, Oleg

    2005-01-01

    Satellite retrievals of the fine-mode fraction (FMF) of midvisible aerosol optical depth, tau, are potentially valuable for constraining chemical transport models and for assessing the global distribution of anthropogenic aerosols. Here we compare satellite retrievals of FMF from the Moderate Resolution Imaging Spectroradiometer (MODIS) to suborbital data on the submicrometer fraction (SMF) of tau. SMF is a closely related parameter that is directly measurable by in situ techniques. The primary suborbital method uses in situ profiling of SMF combined with airborne Sun photometry both to validate the in situ estimate of ambient extinction and to take into account the aerosol above the highest flight level. This method is independent of the satellite retrieval and has well-known accuracy but entails considerable logistical and technical difficulties. An alternate method uses Sun photometer measurements near the surface and an empirical relation between SMF and the Angstrom exponent, A, a measure of the wavelength dependence of optical depth or extinction. Eleven primary and fifteen alternate comparisons are examined involving varying mixtures of dust, sea salt, and pollution in the vicinity of Korea and Japan. MODIS ocean retrievals of FMF are shown to be systematically higher than suborbital estimates of SMF by about 0.2. The most significant cause of this discrepancy involves the relationship between 5 and fine-mode partitioning; in situ measurements indicate a systematically different relationship from what is assumed in the satellite retrievals. Based on these findings, we recommend: (1) satellite programs should concentrate on retrieving and validating since an excellent validation program is in place for doing this, and (2) suborbital measurements should be used to derive relationships between A and fine-mode partitioning to allow interpretation of the satellite data in terms of fine-mode aerosol optical depth.

  6. Linking Remotely Sensed Aerosol Types to Their Chemical Composition

    NASA Technical Reports Server (NTRS)

    Dawson, Kyle William; Kacenelenbogen, Meloe S.; Johnson, Matthew S.; Burton, Sharon P.; Hostetler, Chris A.; Meskhidze, Nicholas

    2016-01-01

    Aerosol types measured during the Ship-Aircraft Bio-Optical Research (SABOR) experiment are related to GEOS-Chem model chemical composition. The application for this procedure to link model chemical components to aerosol type is desirable for understanding aerosol evolution over time. The Mahalanobis distance (DM) statistic is used to cluster model groupings of five chemical components (organic carbon, black carbon, sea salt, dust and sulfate) in a way analogous to the methods used by Burton et al. [2012] and Russell et al. [2014]. First, model-to-measurement evaluation is performed by collocating vertically resolved aerosol extinction from SABOR High Spectral Resolution LiDAR (HSRL) to the GEOS-Chem nested high-resolution data. Comparisons of modeled-to-measured aerosol extinction are shown to be within 35% +/- 14%. Second, the model chemical components are calculation into five variables to calculate the DM and cluster means and covariances for each HSRL-retrieved aerosol type. The layer variables from the model are aerosol optical depth (AOD) ratios of (i) sea salt and (ii) dust to total AOD, mass ratios of (iii) total carbon (i.e. sum of organic and black carbon) to the sum of total carbon and sulfate (iv) organic carbon to black carbon, and (v) the natural log of the aerosol-to-molecular extinction ratio. Third, the layer variables and at most five out of twenty SABOR flights are used to form the pre-specified clusters for calculating DM and to assign an aerosol type. After determining the pre-specified clusters, model aerosol types are produced for the entire vertically resolved GEOS-Chem nested domain over the United States and the model chemical component distributions relating to each type are recorded. Resulting aerosol types are Dust/Dusty Mix, Maritime, Smoke, Urban and Fresh Smoke (separated into 'dark' and 'light' by a threshold of the organic to black carbon ratio). Model-calculated DM not belonging to a specific type (i.e. not meeting a threshold

  7. Linking remotely sensed aerosol types to their chemical composition

    NASA Astrophysics Data System (ADS)

    Dawson, K. W.; Kacenelenbogen, M. S.; Johnson, M. S.; Burton, S. P.; Hostetler, C. A.; Meskhidze, N.

    2016-12-01

    Aerosol types measured during the Ship-Aircraft Bio-Optical Research (SABOR) experiment are related to GEOS-Chem model chemical composition. The application for this procedure to link model chemical components to aerosol type is desirable for understanding aerosol evolution over time. The Mahalanobis distance (DM) statistic is used to cluster model groupings of five chemical components (organic carbon, black carbon, sea salt, dust and sulfate) in a way analogous to the methods used by Burton et al. [2012] and Russell et al. [2014]. First, model-to-measurement evaluation is performed by collocating vertically resolved aerosol extinction from SABOR High Spectral Resolution LiDAR (HSRL) to the GEOS-Chem nested high-resolution data. Comparisons of modeled-to-measured aerosol extinction are shown to be within 35% ± 14%. Second, the model chemical components are calculation into five variables to calculate the DM and cluster means and covariances for each HSRL-retrieved aerosol type. The layer variables from the model are aerosol optical depth (AOD) ratios of (i) sea salt and (ii) dust to total AOD, mass ratios of (iii) total carbon (i.e. sum of organic and black carbon) to the sum of total carbon and sulfate (iv) organic carbon to black carbon, and (v) the natural log of the aerosol-to-molecular extinction ratio. Third, the layer variables and at most five out of twenty SABOR flights are used to form the pre-specified clusters for calculating DM and to assign an aerosol type. After determining the pre-specified clusters, model aerosol types are produced for the entire vertically resolved GEOS-Chem nested domain over the United States and the model chemical component distributions relating to each type are recorded. Resulting aerosol types are Dust/Dusty Mix, Maritime, Smoke, Urban and Fresh Smoke (separated into `dark' and `light' by a threshold of the organic to black carbon ratio). Model-calculated DM not belonging to a specific type (i.e. not meeting a threshold

  8. Final Technical Report for Interagency Agreement No. DE-SC0005453 “Characterizing Aerosol Distributions, Types, and Optical and Microphysical Properties using the NASA Airborne High Spectral Resolution Lidar (HSRL) and the Research Scanning Polarimeter (RSP)”

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hostetler, Chris; Ferrare, Richard

    Measurements of the vertical profile of atmospheric aerosols and aerosol optical and microphysical characteristics are required to: 1) determine aerosol direct and indirect radiative forcing, 2) compute radiative flux and heating rate profiles, 3) assess model simulations of aerosol distributions and types, and 4) establish the ability of surface and space-based remote sensors to measure the indirect effect. Consequently the ASR program calls for a combination of remote sensing and in situ measurements to determine aerosol properties and aerosol influences on clouds and radiation. As part of our previous DOE ASP project, we deployed the NASA Langley airborne High Spectralmore » Resolution Lidar (HSRL) on the NASA B200 King Air aircraft during major field experiments in 2006 (MILAGRO and MaxTEX), 2007 (CHAPS), 2009 (RACORO), and 2010 (CalNex and CARES). The HSRL provided measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm). These measurements were typically made in close temporal and spatial coincidence with measurements made from DOE-funded and other participating aircraft and ground sites. On the RACORO, CARES, and CalNEX missions, we also deployed the NASA Goddard Institute for Space Studies (GISS) Research Scanning Polarimeter (RSP). RSP provided intensity and degree of linear polarization over a broad spectral and angular range enabling column-average retrievals of aerosol optical and microphysical properties. Under this project, we analyzed observations and model results from RACORO, CARES, and CalNex and accomplished the following objectives. 1. Identified aerosol types, characterize the vertical distribution of the aerosol types, and partition aerosol optical depth by type, for CARES and CalNex using HSRL data as we have done for previous missions. 2. Investigated aerosol microphysical and macrophysical properties using the RSP. 3. Used the aerosol backscatter and extinction profiles measured by

  9. Source Attribution of Observed Absorption Profiles During the Two Column Aerosol Project (TCAP) Using a Regional Model

    NASA Astrophysics Data System (ADS)

    Fast, J. D.; Berg, L. K.; Chand, D.; Ferrare, R. A.; Flynn, C. J.; Hostetler, C. A.; Redemann, J.; Sedlacek, A. J., III; Shilling, J.; Shinozuka, Y.; Tomlinson, J. M.; Zelenyuk, A.

    2015-12-01

    Relatively large uncertainties remain in climate model predictions of absorption resulting from black carbon (BC) and brown carbon (BrC). In this study, we focus on comparing simulated profiles of BC, biomass burning aerosols, absorption, and other aerosol optical properties obtained from the regional WRF-Chem model with in situ and remote sensing measurements made during the Department of Energy's Two-Column Aerosol Project (TCAP). TCAP was designed to investigate changes in aerosol mixing state, aerosol radiative forcing, CCN concentration, and cloud-aerosol interactions in two atmospheric columns: one over Cape Cod, Massachusetts and another located approximately 200 km to the east over the ocean. Measurements from the NASA second-generation airborne High Resolution Spectral Lidar reveal the presence distinct aerosol layers associated with the marine boundary layer, residual layer transported over the ocean and in the free troposphere. Analyses of SP2 and aerosol optical measurements indicate that particles in the free troposphere were more 'aged' and had a lower single scattering albebo than for aerosol layers at lower altitudes; however, BC concentrations aloft were lower in the free troposphere. Instead, particle classes derived from the miniSPLAT single particle measurements suggest that the increased absorption aloft may be due biomass burning aerosols. The model suggests that ambient winds likely transported smoke from large wildfires in central Canada as well as smoke from other fires into the sampling domain. The simulated percentage of biomass burning aerosols was consistent with the miniSPLAT data, but the model currently treats all organic matter as non-absorbing. Therefore, we perform sensitivity simulations to examine how the model's absorption and AOD responds to assumptions used for BrC associated with biomass burning and whether the predicted profiles agree with absorption data and wavelength dependent AOD data from 4STAR.

  10. Characterizing and Understanding Aerosol Optical Properties: CARES - Final Report

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cappa, Christopher D; Atkinson, Dean B

    The scientific focus of this study was to use ambient measurements to develop new insights into the understanding of the direct radiative forcing by atmospheric aerosol particles. The study used data collected by the PI’s and others as part of both the 2010 U.S. Department of Energy (DOE) sponsored Carbonaceous Aerosols and Radiative Effects Study (CARES), which took place in and around Sacramento, CA, and the 2012 Clean Air for London (ClearfLo) study. We focus on measurements that were made of aerosol particle optical properties, namely the wavelength-dependent light absorption, scattering and extinction. Interpretation of these optical property measurements ismore » facilitated through consideration of complementary measurements of the aerosol particle chemical composition and size distributions. With these measurements, we addressed the following general scientific questions: 1. How does light scattering and extinction by atmospheric aerosol particles depend on particle composition, water uptake, and size? 2. To what extent is light absorption by aerosol particles enhanced through the mixing of black carbon with other particulate components? 3. What relationships exist between intensive aerosol particle optical properties, and how do these depend on particle source and photochemical aging? 4. How well do spectral deconvolution methods, which are commonly used in remote sensing, retrieve information about particle size distributions?« less

  11. Atmospheric extinction in solar tower plants: the Absorption and Broadband Correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-05-01

    measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from one year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.6%. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8%. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.81%. Therefore, applying this new correction method, both instruments can now be utilized to determine the solar broadband extinction in tower plants sufficiently accurate.

  12. On the Stratospheric Aerosol and Gas Experiment III on the International Space Station

    NASA Technical Reports Server (NTRS)

    Hernandez, Gloria; Zawodny, Joseph M.; Cisewski, Michael S.; Thornton, Brooke M.; Panetta, Andrew D,; Roell, Marilee M.; Vernier, Jean-Paul

    2014-01-01

    The Stratospheric Aerosol and Gas Experiment III on International Space Station (SAGE3/ISS) is anticipated to be delivered to Cape Canaveral in the spring of 2015. This is the fourth generation, fifth instrument, of visible/near-IR solar occultation instruments operated by the National Aeronautics and Space Agency (NASA) to investigate the Earth's upper atmosphere. The instrument is a moderate resolution spectrometer covering wavelengths from 290 nm to 1550 nm. The nominal science products include vertical profiles of trace gases, such as ozone, nitrogen dioxide and water vapor, along with multi-wavelength aerosol extinction. The SAGE3/ISS validation program will be based upon internal consistency of the measurements, detailed analysis of the retrieval algorithm, and comparisons with independent correlative measurements. The Instrument Payload (IP), mission architecture, and major challenges are also discussed.

  13. Atmospheric aerosols: Their Optical Properties and Effects (supplement)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A digest of technical papers is presented. Topics include aerosol size distribution from spectral attenuation with scattering measurements; comparison of extinction and backscattering coefficients for measured and analytic stratospheric aerosol size distributions; using hybrid methods to solve problems in radiative transfer and in multiple scattering; blue moon phenomena; absorption refractive index of aerosols in the Denver pollution cloud; a two dimensional stratospheric model of the dispersion of aerosols from the Fuego volcanic eruption; the variation of the aerosol volume to light scattering coefficient; spectrophone in situ measurements of the absorption of visible light by aerosols; a reassessment of the Krakatoa volcanic turbidity, and multiple scattering in the sky radiance.

  14. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  15. North-south cross sections of the vertical aerosol distribution over the Atlantic Ocean from multiwavelength Raman/polarization lidar during Polarstern cruises

    PubMed Central

    Kanitz, T; Ansmann, A; Engelmann, R; Althausen, D

    2013-01-01

    Shipborne aerosol lidar observations were performed aboard the research vessel Polarstern in 2009 and 2010 during three north-south cruises from about 50°N to 50°S. The aerosol data set provides an excellent opportunity to characterize and contrast the vertical aerosol distribution over the Atlantic Ocean in the polluted northern and relatively clean southern hemisphere. Three case studies, an observed pure Saharan dust plume, a Patagonian dust plume east of South America, and a case of a mixed dust/smoke plume west of Central Africa are exemplarily shown and discussed by means of their optical properties. The meridional transatlantic cruises were used to determine the latitudinal cross section of the aerosol optical thickness (AOT). Profiles of particle backscatter and extinction coefficients are presented as mean profiles for latitudinal belts to contrast northern- and southern-hemispheric aerosol loads and optical effects. Results of lidar observations at Punta Arenas (53°S), Chile, and Stellenbosch (34°S), South Africa, are shown and confirm the lower frequency of occurrence of free-tropospheric aerosol in the southern hemisphere than in the northern hemisphere. The maximum latitudinal mean AOT of 0.27 was found in the northern tropics (0– 15°N) in the Saharan outflow region. Marine AOT is typically 0.05 ± 0.03. Particle optical properties are presented separately for the marine boundary layer and the free troposphere. Concerning the contrast between the anthropogenically influenced midlatitudinal aerosol conditions in the 30– 60°N belt and the respective belt in the southern hemisphere over the remote Atlantic, it is found that the AOT and extinction coefficients for the vertical column from 0–5km (total aerosol column) and 1–5km height (lofted aerosol above the marine boundary layer) are a factor of 1.6 and 2 higher at northern midlatitudes than at respective southern midlatitudes, and a factor of 2.5 higher than at the clean marine southern

  16. In Situ Aerosol Size Distributions and Clear Column Radiative Closure During ACE-2

    NASA Technical Reports Server (NTRS)

    Collins, D. R.; Johnson, H. H.; Seinfeld, J. H.; Flagan, R. C.; Gasso, S.; Hegg, D. A.; Russell, P. B.; Schmid, B.; Livingston, J. M.; Oestroem, E.; hide

    2000-01-01

    As part of the second Aerosol Characterization Experiment (ACE-2) during June and July of 1997, aerosol size distributions were measured on board the CIRPAS Pelican aircraft through the use of a DMA and two OPCS. During the campaign, the boundary layer aerosol typically possessed characteristics representative of a background marine aerosol or a continentally influenced aerosol, while the free tropospheric aerosol was characterized by the presence or absence of a Saharan dust layer. A range of radiative closure comparisons were made using the data obtained during vertical profiles flown on four missions. Of particular interest here are the comparisons made between the optical properties as determined through the use of measured aerosol size distributions and those measured directly by an airborne 14-wavelength sunphotometer and three nephelometers. Variations in the relative humidity associated with each of the direct measurements required consideration of the hygroscopic properties of the aerosol for size distribution based calculations. Simultaneous comparison with such a wide range of directly measured optical parameters not only offers evidence of the validity of the physicochemical description of the aerosol when closure is achieved, but also provides insight into potential sources of error when some or all of the comparisons result in disagreement. Agreement between the derived and directly measured optical properties varied for different measurements and for different cases. Averaged over the four case studies, the derived extinction coefficient at 525 nm exceeded that measured by the sunphotomoter by 2.5% in the clean boundary later, but underestimated measurements by 13% during pollution events. For measurements within the free troposphere, the mean derived extinction coefficient was 3.3% and 17% less than that measured by the sunphotometer during dusty and nondusty conditions, respectively. Likewise, averaged discrepancies between the derived and measured

  17. The Aerosol Models in MODTRAN: Incorporating Selected Measurements From Northern Australia

    DTIC Science & Technology

    2005-12-01

    biomass burning smoke aerosol is modelled assuming the particles are spherical and Mie scattering theory is used to calculate the extinction and...and therefore internally mixed aerosol particles are hygroscopic . Shettle and Fenn model the growth in the size of aerosol particles and changes in...by Sutherland and Khanna [21] was to obtain measurements of the optical properties of organic -based aerosols produced by burning vegetation.

  18. Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Brock, C. A.; Wagner, N. L.; Anderson, B. E.; Attwood, A. R.; Beyersdorf, A.; Campuzano-Jost, P.; Carlton, A. G.; Day, D. A.; Diskin, G. S.; Gordon, T. D.; Jimenez, J. L.; Lack, D. A.; Liao, J.; Markovic, M. Z.; Middlebrook, A. M.; Ng, N. L.; Perring, A. E.; Richardson, M. S.; Schwarz, J. P.; Washenfelder, R. A.; Welti, A.; Xu, L.; Ziemba, L. D.; Murphy, D. M.

    2015-09-01

    Aircraft observations of meteorological, trace gas, and aerosol properties were made during May-September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at three relative humidities and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. Using this approach, the hygroscopicity parameter κ for the organic fraction of the aerosol must have been < 0.10 to be consistent with 75 % of the observations within uncertainties. This subsaturated κ value for the organic aerosol in the southeastern US is consistent with several field studies in rural environments. We present a new parameterization of the change in aerosol extinction as a function of relative humidity that better describes the observations than does the widely used power-law (gamma, γ) parameterization. This new single-parameter κext formulation is based upon κ-Köhler and Mie theories and relies upon the well-known approximately linear relationship between particle volume (or mass) and optical extinction (Charlson et al., 1967). The fitted parameter, κext, is nonlinearly related to the chemically derived κ parameter used in κ-Köhler theory. The values of κext we determined from airborne measurements are consistent with independent observations at a nearby ground site.

  19. MAX-DOAS measurements of aerosol, HCHO, and NO2 over Los Angeles from an elevated mountaintop site

    NASA Astrophysics Data System (ADS)

    Cheung, Ross

    MAX-DOAS measurements of aerosol, HCHO, and NO2 over Los Angeles from an elevated mountaintop site. By. Ross Cheung. Doctor of Philosophy in Atmospheric and Oceanic Sciences. University of California, Los Angeles, 2016. Professor Jochen Stutz, Chair. Differential Optical Absorption Spectroscopy (DOAS) has become a popular technique for measuring atmospheric trace gases using UV/Vis narrow-band absorption features along a light path through the atmosphere. The UCLA Multi-Axis DOAS instrument (MAX-DOAS) is a ground-based spectrometer currently located at Mt. Wilson, California (1700 meters above sea level) that measures solar scattered light at various viewing elevation angles. Since May of 2010, it has been taking regular measurements of atmospheric pollutants in the boundary layer of the atmosphere in and above the Los Angeles Basin. This thesis presents the experimental setup and spectral retrievals, as well as results of our observations of measurements of NO2 and HCHO from Mt. Wilson. Radiative transfer modeling efforts of the deployment at Mt. Wilson will be presented, as well as our efforts to model and account for the effects of clouds and aerosols on MAX-DOAS measurements. Because of the unique challenges presented by aerosols in the ultraviolet and visible light region in a polluted urban boundary layer, new techniques were developed to account for and quantify these effects. Observations of path-integrated NO2 and HCHO, some of the primary precursors to ozone formation in the lower troposphere, as well as aerosol extinctions using the UCLA MAX-DOAS will be presented, and the advantages of a mountaintop measurement strategy will be discussed in light of the amount of vertical information that can be retrieved from this approach. The techniques developed to improve the optimal estimation of vertical aerosol extinction profiles and trace gas concentration profiles will be discussed. Finally, an application of these observations uses the ratio of HCHO/NO2 to

  20. Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of unvertainty in deriving cloud radiative flux

    NASA Astrophysics Data System (ADS)

    Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.

    2017-12-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20 W m-2 after accounting for cloud-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after

  1. Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of unvertainty in deriving cloud radiative flux

    NASA Astrophysics Data System (ADS)

    Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.

    2016-12-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20 W m-2 after accounting for cloud-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after

  2. Sources, seasonality, and trends of Southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

    NASA Astrophysics Data System (ADS)

    Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.

    2015-07-01

    We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the Southeast US during the summer-fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 km × 25 km resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the Southeast US. GEOS-Chem simulation of sulfate requires a missing oxidant, taken here to be stabilized Criegee intermediates, but which could alternatively reflect an unaccounted for heterogeneous process. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 20 % in the cloud convective layer at 1.5-3 km, and 20 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42-] + [NO3-])) is only 0.5-0.7 mol mol-1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by organic aerosol. This would explain the long-term decline of ammonium aerosol in the Southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the Southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the Southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 21 %. The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from

  3. A Compact Airborne High Spectral Resolution Lidar for Observations of Aerosol and Cloud Optical Properties

    NASA Technical Reports Server (NTRS)

    Hostetler, Chris A.; Hair, John W.; Cook, Anthony L.

    2002-01-01

    We are in the process of developing a nadir-viewing, aircraft-based high spectral resolution lidar (HSRL) at NASA Langley Research Center. The system is designed to measure backscatter and extinction of aerosols and tenuous clouds. The primary uses of the instrument will be to validate spaceborne aerosol and cloud observations, carry out regional process studies, and assess the predictions of chemical transport models. In this paper, we provide an overview of the instrument design and present the results of simulations showing the instrument's capability to accurately measure extinction and extinction-to-backscatter ratio.

  4. Development the EarthCARE aerosol classification scheme

    NASA Astrophysics Data System (ADS)

    Wandinger, Ulla; Baars, Holger; Hünerbein, Anja; Donovan, Dave; van Zadelhoff, Gerd-Jan; Fischer, Jürgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias

    2015-04-01

    The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is a joint ESA/JAXA mission planned to be launched in 2018. The multi-sensor platform carries a cloud-profiling radar (CPR), a high-spectral-resolution cloud/aerosol lidar (ATLID), a cloud/aerosol multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR). Three out of the four instruments (ATLID, MSI, and BBR) will be able to sense the global aerosol distribution and contribute to the overarching EarthCARE goals of sensor synergy and radiation closure with respect to aerosols. The high-spectral-resolution lidar ATLID obtains profiles of particle extinction and backscatter coefficients, lidar ratio, and linear depolarization ratio as well as the aerosol optical thickness (AOT) at 355 nm. MSI provides AOT at 670 nm (over land and ocean) and 865 nm (over ocean). Next to these primary observables the aerosol type is one of the required products to be derived from both lidar stand-alone and ATLID-MSI synergistic retrievals. ATLID measurements of the aerosol intensive properties (lidar ratio, depolarization ratio) and ATLID-MSI observations of the spectral AOT will provide the basic input for aerosol-type determination. Aerosol typing is needed for the quantification of anthropogenic versus natural aerosol loadings of the atmosphere, the investigation of aerosol-cloud interaction, assimilation purposes, and the validation of atmospheric transport models which carry components like dust, sea salt, smoke and pollution. Furthermore, aerosol classification is a prerequisite for the estimation of direct aerosol radiative forcing and radiative closure studies. With an appropriate underlying microphysical particle description, the categorization of aerosol observations into predefined aerosol types allows us to infer information needed for the calculation of shortwave radiative effects, such as mean particle size, single-scattering albedo, and spectral conversion factors. In order to ensure

  5. An Alternative Retrieval Algorithm for the Ozone Mapping and Profiler Suite Limb Profiler

    DTIC Science & Technology

    2012-05-01

    behavior of aerosol extinction from the upper troposphere through the stratosphere is critical for retrieving ozone in this region. Aerosol scattering is......include area code) b. ABSTRACT c. THIS PAGE 18. NUMBER OF PAGES 17. LIMITATION OF ABSTRACT An Alternative Retrieval Algorithm for the Ozone Mapping and

  6. Global climate change driven by soot at the K-Pg boundary as the cause of the mass extinction

    NASA Astrophysics Data System (ADS)

    Kaiho, Kunio; Oshima, Naga; Adachi, Kouji; Adachi, Yukimasa; Mizukami, Takuya; Fujibayashi, Megumu; Saito, Ryosuke

    2016-07-01

    The mass extinction of life 66 million years ago at the Cretaceous/Paleogene boundary, marked by the extinctions of dinosaurs and shallow marine organisms, is important because it led to the macroevolution of mammals and appearance of humans. The current hypothesis for the extinction is that an asteroid impact in present-day Mexico formed condensed aerosols in the stratosphere, which caused the cessation of photosynthesis and global near-freezing conditions. Here, we show that the stratospheric aerosols did not induce darkness that resulted in milder cooling than previously thought. We propose a new hypothesis that latitude-dependent climate changes caused by massive stratospheric soot explain the known mortality and survival on land and in oceans at the Cretaceous/Paleogene boundary. The stratospheric soot was ejected from the oil-rich area by the asteroid impact and was spread globally. The soot aerosols caused sufficiently colder climates at mid-high latitudes and drought with milder cooling at low latitudes on land, in addition to causing limited cessation of photosynthesis in global oceans within a few months to two years after the impact, followed by surface-water cooling in global oceans in a few years. The rapid climate change induced terrestrial extinctions followed by marine extinctions over several years.

  7. Global climate change driven by soot at the K-Pg boundary as the cause of the mass extinction

    PubMed Central

    Kaiho, Kunio; Oshima, Naga; Adachi, Kouji; Adachi, Yukimasa; Mizukami, Takuya; Fujibayashi, Megumu; Saito, Ryosuke

    2016-01-01

    The mass extinction of life 66 million years ago at the Cretaceous/Paleogene boundary, marked by the extinctions of dinosaurs and shallow marine organisms, is important because it led to the macroevolution of mammals and appearance of humans. The current hypothesis for the extinction is that an asteroid impact in present-day Mexico formed condensed aerosols in the stratosphere, which caused the cessation of photosynthesis and global near-freezing conditions. Here, we show that the stratospheric aerosols did not induce darkness that resulted in milder cooling than previously thought. We propose a new hypothesis that latitude-dependent climate changes caused by massive stratospheric soot explain the known mortality and survival on land and in oceans at the Cretaceous/Paleogene boundary. The stratospheric soot was ejected from the oil-rich area by the asteroid impact and was spread globally. The soot aerosols caused sufficiently colder climates at mid–high latitudes and drought with milder cooling at low latitudes on land, in addition to causing limited cessation of photosynthesis in global oceans within a few months to two years after the impact, followed by surface-water cooling in global oceans in a few years. The rapid climate change induced terrestrial extinctions followed by marine extinctions over several years. PMID:27414998

  8. Global climate change driven by soot at the K-Pg boundary as the cause of the mass extinction.

    PubMed

    Kaiho, Kunio; Oshima, Naga; Adachi, Kouji; Adachi, Yukimasa; Mizukami, Takuya; Fujibayashi, Megumu; Saito, Ryosuke

    2016-07-14

    The mass extinction of life 66 million years ago at the Cretaceous/Paleogene boundary, marked by the extinctions of dinosaurs and shallow marine organisms, is important because it led to the macroevolution of mammals and appearance of humans. The current hypothesis for the extinction is that an asteroid impact in present-day Mexico formed condensed aerosols in the stratosphere, which caused the cessation of photosynthesis and global near-freezing conditions. Here, we show that the stratospheric aerosols did not induce darkness that resulted in milder cooling than previously thought. We propose a new hypothesis that latitude-dependent climate changes caused by massive stratospheric soot explain the known mortality and survival on land and in oceans at the Cretaceous/Paleogene boundary. The stratospheric soot was ejected from the oil-rich area by the asteroid impact and was spread globally. The soot aerosols caused sufficiently colder climates at mid-high latitudes and drought with milder cooling at low latitudes on land, in addition to causing limited cessation of photosynthesis in global oceans within a few months to two years after the impact, followed by surface-water cooling in global oceans in a few years. The rapid climate change induced terrestrial extinctions followed by marine extinctions over several years.

  9. Aerosol Radiative Forcing in Asian Continental Outflow

    NASA Technical Reports Server (NTRS)

    Pueschel, R.; Kinne, S.; Redemann, J.; Gore, Warren J. (Technical Monitor)

    2000-01-01

    Aerosols in elevated layers were sampled with FSSP-probes and wire impactors over the Pacific ocean aboard the NASA DC-8 aircraft. Analyses of particle size and morphology identifies two distinctly different aerosol types for cases when the mid-visible extinctions exceed 0.2/km. Smaller sizes (effective radii of 0.2 um) and moderate absorption (mid-visible single scattering albedo of.935) are typical for urban-industrial pollution. Larger sizes (effective radii of 0.7 um) and weak absorption (mid-visible single scattering albedo of 0.985) identify dust. This aerosol classification is in agreement with its origin as determined by airmass back trajectory analysis. Based on lidar vertical profiling, aerosol dominated by dust and urban-industrial pollution above 3km were assigned mid-visible optical depths of 0.50 and 0.27, respectively. Radiative transfer simulations, considering a 50% cloud-cover below the aerosol layers, suggest (on a daily tP C)C> basis) small reductions (-4W/m2) to the energy budget at the top of the atmosphere for both aerosol types. For c' 0 dust, more backscattering of sunlight (weaker solar absorption) is compensated by a stronger greenhouse effect due to larger sizes. Forced reductions to the energy budget at the surface are 12W/m2 for both aerosol types. In contrast, impacts on heating rates within the aerosol layers are quite different: While urban-industrial aerosol warms the layer (at +0.6K/day as solar heating dominates), dust cools (at -0.5K/day as infrared cooling dominates). Sensitivity tests show the dependence of the aerosol climatic impact on the optical depth, particle size, absorptivity, and altitude of the layers, as well as clouds and surface properties. Climatic cooling can be eliminated (1) for the urban-industrial aerosol if absorption is increased to yield a mid-visible single scattering albedo of 0.89, or if the ocean is replaced by a land surface; (2) for the dust aerosol if the effective radius is increased from 0.7 to 1

  10. Sources, seasonality, and trends of southeast US aerosol: an integrated analysis of surface, aircraft, and satellite observations with the GEOS-Chem chemical transport model

    NASA Astrophysics Data System (ADS)

    Kim, P. S.; Jacob, D. J.; Fisher, J. A.; Travis, K.; Yu, K.; Zhu, L.; Yantosca, R. M.; Sulprizio, M. P.; Jimenez, J. L.; Campuzano-Jost, P.; Froyd, K. D.; Liao, J.; Hair, J. W.; Fenn, M. A.; Butler, C. F.; Wagner, N. L.; Gordon, T. D.; Welti, A.; Wennberg, P. O.; Crounse, J. D.; St. Clair, J. M.; Teng, A. P.; Millet, D. B.; Schwarz, J. P.; Markovic, M. Z.; Perring, A. E.

    2015-09-01

    We use an ensemble of surface (EPA CSN, IMPROVE, SEARCH, AERONET), aircraft (SEAC4RS), and satellite (MODIS, MISR) observations over the southeast US during the summer-fall of 2013 to better understand aerosol sources in the region and the relationship between surface particulate matter (PM) and aerosol optical depth (AOD). The GEOS-Chem global chemical transport model (CTM) with 25 × 25 km2 resolution over North America is used as a common platform to interpret measurements of different aerosol variables made at different times and locations. Sulfate and organic aerosol (OA) are the main contributors to surface PM2.5 (mass concentration of PM finer than 2.5 μm aerodynamic diameter) and AOD over the southeast US. OA is simulated successfully with a simple parameterization, assuming irreversible uptake of low-volatility products of hydrocarbon oxidation. Biogenic isoprene and monoterpenes account for 60 % of OA, anthropogenic sources for 30 %, and open fires for 10 %. 60 % of total aerosol mass is in the mixed layer below 1.5 km, 25 % in the cloud convective layer at 1.5-3 km, and 15 % in the free troposphere above 3 km. This vertical profile is well captured by GEOS-Chem, arguing against a high-altitude source of OA. The extent of sulfate neutralization (f = [NH4+]/(2[SO42-] + [NO3-]) is only 0.5-0.7 mol mol-1 in the observations, despite an excess of ammonia present, which could reflect suppression of ammonia uptake by OA. This would explain the long-term decline of ammonium aerosol in the southeast US, paralleling that of sulfate. The vertical profile of aerosol extinction over the southeast US follows closely that of aerosol mass. GEOS-Chem reproduces observed total column aerosol mass over the southeast US within 6 %, column aerosol extinction within 16 %, and space-based AOD within 8-28 % (consistently biased low). The large AOD decline observed from summer to winter is driven by sharp declines in both sulfate and OA from August to October. These declines

  11. Global View of Aerosol Vertical Distributions from CALIPSO Lidar Measurements and GOCART Simulations: Regional and Seasonal Variations

    NASA Technical Reports Server (NTRS)

    Yu, Hongbin; Chin, Mian; Winker, David M.; Omar, Ali H.; Liu, Zhaoyan; Kittaka, Chieko; Diehl, Thomas

    2010-01-01

    This study examines seasonal variations of the vertical distribution of aerosols through a statistical analysis of the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar observations from June 2006 to November 2007. A data-screening scheme is developed to attain good quality data in cloud-free conditions, and the polarization measurement is used to separate dust from non-dust aerosol. The CALIPSO aerosol observations are compared with aerosol simulations from the Goddard Chemistry Aerosol Radiation Transport (GOCART) model and aerosol optical depth (AOD) measurements from the MODerate resolution Imaging Spectroradiometer (MODIS). The CALIPSO observations of geographical patterns and seasonal variations of AOD are generally consistent with GOCART simulations and MODIS retrievals especially near source regions, while the magnitude of AOD shows large discrepancies in most regions. Both the CALIPSO observation and GOCART model show that the aerosol extinction scale heights in major dust and smoke source regions are generally higher than that in industrial pollution source regions. The CALIPSO aerosol lidar ratio also generally agrees with GOCART model within 30% on regional scales. Major differences between satellite observations and GOCART model are identified, including (1) an underestimate of aerosol extinction by GOCART over the Indian sub-continent, (2) much larger aerosol extinction calculated by GOCART than observed by CALIPSO in dust source regions, (3) much weaker in magnitude and more concentrated aerosol in the lower atmosphere in CALIPSO observation than GOCART model over transported areas in midlatitudes, and (4) consistently lower aerosol scale height by CALIPSO observation than GOCART model. Possible factors contributing to these differences are discussed.

  12. Comparing multiple model-derived aerosol optical properties to spatially collocated ground-based and satellite measurements

    NASA Astrophysics Data System (ADS)

    Ocko, Ilissa B.; Ginoux, Paul A.

    2017-04-01

    Anthropogenic aerosols are a key factor governing Earth's climate and play a central role in human-caused climate change. However, because of aerosols' complex physical, optical, and dynamical properties, aerosols are one of the most uncertain aspects of climate modeling. Fortunately, aerosol measurement networks over the past few decades have led to the establishment of long-term observations for numerous locations worldwide. Further, the availability of datasets from several different measurement techniques (such as ground-based and satellite instruments) can help scientists increasingly improve modeling efforts. This study explores the value of evaluating several model-simulated aerosol properties with data from spatially collocated instruments. We compare aerosol optical depth (AOD; total, scattering, and absorption), single-scattering albedo (SSA), Ångström exponent (α), and extinction vertical profiles in two prominent global climate models (Geophysical Fluid Dynamics Laboratory, GFDL, CM2.1 and CM3) to seasonal observations from collocated instruments (AErosol RObotic NETwork, AERONET, and Cloud-Aerosol Lidar with Orthogonal Polarization, CALIOP) at seven polluted and biomass burning regions worldwide. We find that a multi-parameter evaluation provides key insights on model biases, data from collocated instruments can reveal underlying aerosol-governing physics, column properties wash out important vertical distinctions, and improved models does not mean all aspects are improved. We conclude that it is important to make use of all available data (parameters and instruments) when evaluating aerosol properties derived by models.

  13. The Angstrom Exponent and Bimodal Aerosol Size Distributions

    NASA Technical Reports Server (NTRS)

    Schuster, Gregory L.; Dubovik, Oleg; Holben, Brent H.

    2005-01-01

    Powerlaws have long been used to describe the spectral dependence of aerosol extinction, and the wavelength exponent of the aerosol extinction powerlaw is commonly referred to as the Angstrom exponent. The Angstrom exponent is often used as a qualitative indicator of aerosol particle size, with values greater than two indicating small particles associated with combustion byproducts, and values less than one indicating large particles like sea salt and dust. In this study, we investigate the relationship between the Angstrom exponent and the mode parameters of bimodal aerosol size distributions using Mie theory calculations and Aerosol Robotic Network (AERONET) retrievals. We find that Angstrom exponents based upon seven wavelengths (0.34, 0.38, 0.44, 0.5, 0.67, 0.87, and 1.02 micrometers) are sensitive to the volume fraction of aerosols with radii less then 0.6 micrometers, but not to the fine mode effective radius. The Angstrom exponent is also known to vary with wavelength, which is commonly referred to as curvature; we show how the spectral curvature can provide additional information about aerosol size distributions for intermediate values of the Angstrom exponent. Curvature also has a significant effect on the conclusions that can be drawn about two-wavelength Angstrom exponents; long wavelengths (0.67, 0.87 micrometers) are sensitive to fine mode volume fraction of aerosols but not fine mode effective radius, while short wavelengths (0.38, 0.44 micrometers) are sensitive to the fine mode effective radius but not the fine mode volume fraction.

  14. Extinction-to-Backscatter Ratios of Saharan Dust Layers Derived from In-Situ Measurements and CALIPSO Overflights During NAMMA

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Liu, Zhaoyan; Vaughan, Mark A.; Hu, Yongxiang; Ismail, Syed; Powell, Kathleen A.; Winker, David M.; Trepte, Charles R.; Anderson, Bruce E.

    2010-01-01

    We determine the aerosol extinction-to-backscatter (Sa) ratios of dust using airborne in-situ measurements of microphysical properties, and CALIPSO observations during the NASA African Monsoon Multidisciplinary Analyses (NAMMA). The NAMMA field experiment was conducted from Sal, Cape Verde during Aug-Sept 2006. Using CALIPSO measurements of the attenuated backscatter of lofted Saharan dust layers, we apply the transmittance technique to estimate dust Sa ratios at 532 nm and a 2-color method to determine the corresponding 1064 nm Sa. Using this method, we found dust Sa ratios of 39.8 plus or minus 1.4 sr and 51.8 plus or minus 3.6 sr at 532 nm and 1064 nm, respectively. Secondly, Sa ratios at both wavelengths is independently calculated using size distributions measured aboard the NASA DC-8 and estimates of Saharan dust complex refractive indices applied in a T-Matrix scheme. We found Sa ratios of 39.1 plus or minus 3.5 sr and 50.0 plus or minus 4 sr at 532 nm and 1064 nm, respectively, using the T-Matrix calculations applied to measured size spectra. Finally, in situ measurements of the total scattering (550 nm) and absorption coefficients (532 nm) are used to generate an extinction profile that is used to constrain the CALIPSO 532 nm extinction profile.

  15. Retrievals of Profiles of Fine And Coarse Aerosols Using Lidar And Radiometric Space Measurements

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Tanre, Didier; Leon, Jean-Francois; Pelon, Jacques; Lau, William K. M. (Technical Monitor)

    2002-01-01

    In couple of years we expect the launch of the CALIPSO lidar spaceborne mission designed to observe aerosols and clouds. CALIPSO will collect profiles of the lidar attenuated backscattering coefficients in two spectral wavelengths (0.53 and 1.06 microns). Observations are provided along the track of the satellite around the globe from pole to pole. The attenuated backscattering coefficients are sensitive to the vertical distribution of aerosol particles, their shape and size. However the information is insufficient to be mapped into unique aerosol physical properties and vertical distribution. Infinite number of physical solutions can reconstruct the same two wavelength backscattered profile measured from space. CALIPSO will fly in formation with the Aqua satellite and the MODIS spectro-radiometer on board. Spectral radiances measured by MODIS in six channels between 0.55 and 2.13 microns simultaneously with the CALIPSO observations can constrain the solutions and resolve this ambiguity, albeit under some assumptions. In this paper we describe the inversion method and apply it to aircraft lidar and MODIS data collected over a dust storm off the coast of West Africa during the SHADE experiment. It is shown that the product of the single scattering albedo, omega, and the phase function, P, for backscattering can be retrieved from the synergism between measurements avoiding a priori hypotheses required for inverting lidar measurements alone. The resultant value of (omega)P(180 deg.) = 0.016/sr are significantly different from what is expected using Mie theory, but are in good agreement with recent results obtained from lidar observations of dust episodes. The inversion is robust in the presence of noise of 10% and 20% in the lidar signal in the 0.53 and 1.06 pm channels respectively. Calibration errors of the lidar of 5 to 10% can cause an error in optical thickness of 20 to 40% respectively in the tested cases. The lidar calibration errors cause degradation in the

  16. Trans-Pacific transport and evolution of aerosols: Evaluation of quasi-global WRF-Chem simulation with multiple observations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hu, Zhiyuan; Zhao, Chun; Huang, Jianping

    A fully coupled meteorology-chemistry model (WRF-Chem, the Weather Research and Forecasting model coupled with chemistry) has been configured to conduct quasi-global simulation for 5 years (2010–2014) and evaluated with multiple observation data sets for the first time. The evaluation focuses on the simulation over the trans-Pacific transport region using various reanalysis and observational data sets for meteorological fields and aerosol properties. The simulation generally captures the overall spatial and seasonal variability of satellite retrieved aerosol optical depth (AOD) and absorbing AOD (AAOD) over the Pacific that is determined by the outflow of pollutants and dust and the emissions of marine aerosols.more » The assessment of simulated extinction Ångström exponent (EAE) indicates that the model generally reproduces the variability of aerosol size distributions as seen by satellites. In addition, the vertical profile of aerosol extinction and its seasonality over the Pacific are also well simulated. The difference between the simulation and satellite retrievals can be mainly attributed to model biases in estimating marine aerosol emissions as well as the satellite sampling and retrieval uncertainties. Compared with the surface measurements over the western USA, the model reasonably simulates the observed magnitude and seasonality of dust, sulfate, and nitrate surface concentrations, but significantly underestimates the peak surface concentrations of carbonaceous aerosol likely due to model biases in the spatial and temporal variability of biomass burning emissions and secondary organic aerosol (SOA) production. A sensitivity simulation shows that the trans-Pacific transported dust, sulfate, and nitrate can make significant contribution to surface concentrations over the rural areas of the western USA, while the peaks of carbonaceous aerosol surface concentrations are dominated by the North American emissions. Both the retrievals and simulation show

  17. Trans-Pacific transport and evolution of aerosols: Evaluation of quasi-global WRF-Chem simulation with multiple observations

    DOE PAGES

    Hu, Zhiyuan; Zhao, Chun; Huang, Jianping; ...

    2016-05-10

    A fully coupled meteorology-chemistry model (WRF-Chem, the Weather Research and Forecasting model coupled with chemistry) has been configured to conduct quasi-global simulation for 5 years (2010–2014) and evaluated with multiple observation data sets for the first time. The evaluation focuses on the simulation over the trans-Pacific transport region using various reanalysis and observational data sets for meteorological fields and aerosol properties. The simulation generally captures the overall spatial and seasonal variability of satellite retrieved aerosol optical depth (AOD) and absorbing AOD (AAOD) over the Pacific that is determined by the outflow of pollutants and dust and the emissions of marine aerosols.more » The assessment of simulated extinction Ångström exponent (EAE) indicates that the model generally reproduces the variability of aerosol size distributions as seen by satellites. In addition, the vertical profile of aerosol extinction and its seasonality over the Pacific are also well simulated. The difference between the simulation and satellite retrievals can be mainly attributed to model biases in estimating marine aerosol emissions as well as the satellite sampling and retrieval uncertainties. Compared with the surface measurements over the western USA, the model reasonably simulates the observed magnitude and seasonality of dust, sulfate, and nitrate surface concentrations, but significantly underestimates the peak surface concentrations of carbonaceous aerosol likely due to model biases in the spatial and temporal variability of biomass burning emissions and secondary organic aerosol (SOA) production. A sensitivity simulation shows that the trans-Pacific transported dust, sulfate, and nitrate can make significant contribution to surface concentrations over the rural areas of the western USA, while the peaks of carbonaceous aerosol surface concentrations are dominated by the North American emissions. Both the retrievals and simulation show

  18. Trans-Pacific transport and evolution of aerosols: evaluation of quasi-global WRF-Chem simulation with multiple observations

    NASA Astrophysics Data System (ADS)

    Hu, Zhiyuan; Zhao, Chun; Huang, Jianping; Leung, L. Ruby; Qian, Yun; Yu, Hongbin; Huang, Lei; Kalashnikova, Olga V.

    2016-05-01

    A fully coupled meteorology-chemistry model (WRF-Chem, the Weather Research and Forecasting model coupled with chemistry) has been configured to conduct quasi-global simulation for 5 years (2010-2014) and evaluated with multiple observation data sets for the first time. The evaluation focuses on the simulation over the trans-Pacific transport region using various reanalysis and observational data sets for meteorological fields and aerosol properties. The simulation generally captures the overall spatial and seasonal variability of satellite retrieved aerosol optical depth (AOD) and absorbing AOD (AAOD) over the Pacific that is determined by the outflow of pollutants and dust and the emissions of marine aerosols. The assessment of simulated extinction Ångström exponent (EAE) indicates that the model generally reproduces the variability of aerosol size distributions as seen by satellites. In addition, the vertical profile of aerosol extinction and its seasonality over the Pacific are also well simulated. The difference between the simulation and satellite retrievals can be mainly attributed to model biases in estimating marine aerosol emissions as well as the satellite sampling and retrieval uncertainties. Compared with the surface measurements over the western USA, the model reasonably simulates the observed magnitude and seasonality of dust, sulfate, and nitrate surface concentrations, but significantly underestimates the peak surface concentrations of carbonaceous aerosol likely due to model biases in the spatial and temporal variability of biomass burning emissions and secondary organic aerosol (SOA) production. A sensitivity simulation shows that the trans-Pacific transported dust, sulfate, and nitrate can make significant contribution to surface concentrations over the rural areas of the western USA, while the peaks of carbonaceous aerosol surface concentrations are dominated by the North American emissions. Both the retrievals and simulation show small

  19. Lessons learned and way forward from 6 years of Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Popp, Thomas; de Leeuw, Gerrit; Pinnock, Simon

    2017-04-01

    Within the ESA Climate Change Initiative (CCI) Aerosol_cci (2010 - 2017) conducts intensive work to improve and qualify algorithms for the retrieval of aerosol information from European sensors. Meanwhile, several validated (multi-) decadal time series of different aerosol parameters from complementary sensors are available: Aerosol Optical Depth (AOD), stratospheric extinction profiles, a qualitative Absorbing Aerosol Index (AAI), fine mode AOD, mineral dust AOD; absorption information and aerosol layer height are in an evaluation phase and the multi-pixel GRASP algorithm for the POLDER instrument is used for selected regions. Validation (vs. AERONET, MAN) and inter-comparison to other satellite datasets (MODIS, MISR, SeaWIFS) proved the high quality of the available datasets comparable to other satellite retrievals and revealed needs for algorithm improvement (for example for higher AOD values) which were taken into account in an iterative evolution cycle. The datasets contain pixel level uncertainty estimates which were also validated and improved in the reprocessing. The use of an ensemble method was tested, where several algorithms are applied to the same sensor. The presentation will summarize and discuss the lessons learned from the 6 years of intensive collaboration and highlight major achievements (significantly improved AOD quality, fine mode AOD, dust AOD, pixel level uncertainties, ensemble approach); also limitations and remaining deficits shall be discussed. An outlook will discuss the way forward for the continuous algorithm improvement and re-processing together with opportunities for time series extension with successor instruments of the Sentinel family and the complementarity of the different satellite aerosol products.

  20. Aerosol Radiative Forcing over North India during Pre-Monsoon Season using WRF-Chem

    NASA Astrophysics Data System (ADS)

    Misra, A.; Kumar, K.; Michael, M.; Tripathi, S. N.

    2013-12-01

    Study of aerosols is important for a fair understanding of the Earth climate system. This requires knowledge of the physical, chemical, optical, and morphological properties of aerosols. Aerosol radiative forcing provides information on the effect of aerosols on the Earth radiation budget. Radiative forcing estimates using model data provide an opportunity to examine the contribution of individual aerosol species to overall radiative forcing. We have used Weather Research and Forecast with Online Chemistry (WRF-Chem) derived aerosol concentration data to compute aerosol radiative forcing over north India during pre-monsoon season of 2008, 2009, and 2010. WRF-Chem derived mass concentrations are converted to number concentrations using standard procedure. Optical Properties of Aerosol and Cloud (OPAC) software package is used to compute extinction and scattering coefficients, and asymmetry parameter. Computations are performed at different altitudes and the obtained values are integrated to get the column optical properties. Santa Barbara Discrete Ordinate Radiative Transfer (SBDART) model is used to calculate the radiative forcing at surface and top-of-atmosphere. Higher values of aerosol radiative forcing are observed over desert region in western Indian state of Rajasthan, and Punjab of Pakistan. Contribution of individual aerosol species to atmospheric radiative forcing is also assessed. Dust radiative forcing is high over western India. Radiative forcing due to BC and water-soluble (WASO) aerosols are higher over north-west Indian states of Punjab and Haryana, and the Indo-Gangetic Basin. A pool of high WASO optical depth and radiative forcing is observed over the Indo-Bangladesh border. The findings of aerosol optical depth and radiative forcing are consistent with the geography and prevailing aerosol climatology of various regions. Heating rate profiles due to total aerosols and only due to BC have been evaluated at selected stations in north India. They show

  1. Vertical Structure of Aerosols and Mineral Dust Over the Bay of Bengal From Multisatellite Observations

    NASA Astrophysics Data System (ADS)

    Lakshmi, N. B.; Nair, Vijayakumar S.; Suresh Babu, S.

    2017-12-01

    The vertical distribution of aerosol and dust extinction coefficient over the Bay of Bengal is examined using the satellite observations (Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and Moderate Resolution Imaging Spectroradiometer (MODIS)) for the period from 2006 to 2017. Distinct seasonal pattern is observed in the vertical structure of both aerosol and dust over the Bay of Bengal with an enhancement of 24% in the aerosol extinction above 1 km from winter (December, January and February) to premonsoon (March, April, and May). Significant contribution of dust is observed over the northern Bay of Bengal during premonsoon season where 22% of the total aerosol extinction is contributed by dust aerosols transported from the nearby continental regions. During winter, dust transport is found to be less significant with fractional contribution of 10%-13% to the total aerosol optical depth over the Bay of Bengal. MODIS-derived dust fraction (fine mode based) shows an overestimation up to twofold compared to CALIOP dust fraction (depolarization based), whereas the Goddard Chemistry Aerosol Radiation and Transport-simulated dust fraction underestimates the satellite-derived dust fractions over the Bay of Bengal. Though the long-term variation in dust aerosol showed a decreasing trend over the Bay of Bengal, the confidence level is insufficient in establishing the robustness of the observed trend. However, significant dust-induced heating is observed above the boundary layer during premonsoon season. This dust-induced elevated heating can affect the convection over the Bay of Bengal which will have implication on the monsoon dynamics over the Indian region.

  2. Use of the NASA GEOS-5 SEAC4RS Meteorological and Aerosol Reanalysis for assessing simulated aerosol optical properties as a function of smoke age

    NASA Astrophysics Data System (ADS)

    Randles, C. A.; da Silva, A. M., Jr.; Colarco, P. R.; Darmenov, A.; Buchard, V.; Govindaraju, R.; Chen, G.; Hair, J. W.; Russell, P. B.; Shinozuka, Y.; Wagner, N.; Lack, D.

    2014-12-01

    The NASA Goddard Earth Observing System version 5 (GEOS-5) Earth system model, which includes an online aerosol module, provided chemical and weather forecasts during the SEAC4RS field campaign. For post-mission analysis, we have produced a high resolution (25 km) meteorological and aerosol reanalysis for the entire campaign period. In addition to the full meteorological observing system used for routine NWP, we assimilate 550 nm aerosol optical depth (AOD) derived from MODIS (both Aqua and Terra satellites), ground-based AERONET sun photometers, and the MISR instrument (over bright surfaces only). Daily biomass burning emissions of CO, CO2, SO2, and aerosols are derived from MODIS fire radiative power retrievals. We have also introduced novel smoke "age" tracers, which provide, for a given time, a snapshot histogram of the age of simulated smoke aerosol. Because GEOS-5 assimilates remotely sensed AOD data, it generally reproduces observed (column) AOD compared to, for example, the airborne 4-STAR instrument. Constraining AOD, however, does not imply a good representation of either the vertical profile or the aerosol microphysical properties (e.g., composition, absorption). We do find a reasonable vertical structure for aerosols is attained in the model, provided actual smoke injection heights are not much above the planetary boundary layer, as verified with observations from DIAL/HRSL aboard the DC8. The translation of the simulated aerosol microphysical properties to total column AOD, needed in the aerosol assimilation step, is based on prescribed mass extinction efficiencies that depend on wavelength, composition, and relative humidity. Here we also evaluate the performance of the simulated aerosol speciation by examining in situ retrievals of aerosol absorption/single scattering albedo and scattering growth factor (f(RH)) from the LARGE and AOP suite of instruments. Putting these comparisons in the context of smoke age as diagnosed by the model helps us to

  3. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosols

    NASA Technical Reports Server (NTRS)

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the first two years of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this two-year grant consisted in the development and deployment of a new in-situ capability for measuring aerosol 180' backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Measurements were made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with targeted in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator and radiative transfer modeling by the University of Lille, France.

  4. Coupling Satellite and Ground-Based Instruments to Map Climate Forcing by Anthropogenic Aerosol

    NASA Technical Reports Server (NTRS)

    Charlson, Robert J.; Anderson, Theodore L.; Hostetler, Chris (Technical Monitor)

    2000-01-01

    Climate forcing by anthropogenic aerosols is a significant but highly uncertain factor in global climate change. Only satellites can offer the global coverage essential to reducing this uncertainty; however, satellite measurements must be coupled with correlative, in situ measurements both to constrain the aerosol optical properties required in satellite retrieval algorithms and to provide chemical identification of aerosol sources. This grant funded the third year of a three-year project which seeks to develop methodologies for combining spaceborne lidar with in-situ aerosol data sets to improve estimates of direct aerosol climate forcing. Progress under this one-year grant consisted in analysis and publication of field studies using a new in-situ capability for measuring aerosol 180 deg backscatter and the extinction-to-backscatter ratio. This new measurement capacity allows definitive lidar/in-situ comparisons and improves our ability to interpret lidar data in terms of climatically relevant quantities such as the extinction coefficient and optical depth. Analyzed data consisted of measurements made along the coast of Washington State, in Central Illinois, over the Indian Ocean, and in the Central Pacific. Thus, this research, combined with previous measurements by others, is rapidly building toward a global data set of extinction-to-backscatter ratio for key aerosol types. Such information will be critical to interpreting lidar data from the upcoming PICASSO-CENA, or P-C, satellite mission. Another aspect of this project is to investigate innovative ways to couple the lidar-satellite signal with target in-situ measurements toward a direct determination of aerosol forcing. This aspect is progressing in collaboration with NASA Langley's P-C lidar simulator.

  5. Aerosol Optical Properties at the Ground Sites during the 2010 CARES Field Campaign

    NASA Astrophysics Data System (ADS)

    Atkinson, D. B.; Radney, J. G.; Harworth, J. W.

    2010-12-01

    Preliminary results from the ground sites at the 2010 CARES field campaign (T0 near Sacramento, CA and T1 near Cool, CA) will be presented. A number of aerosol optical properties were measured at high time resolution for the four week study period using custom instruments. The aerosol extinction coefficient was measured at T0 using a cavity ring-down transmissometer (CRDT) at two wavelengths (532 and 1064 nm) and the aerosol scattering coefficient was measured at 532 nm using a Radiance Research M903 nephelometer. At T1, a new CRDT instrument was deployed that measured the extinction coefficient at three wavelengths (355, 532, and 1064 nm) for sub-10 μm (nominal) and sub-2.5 μm aerosols at ambient, elevated, and reduced relative humidity. A new type of custom nephelometer that measures the aerosol scattering coefficient at 532 nm using an array detector was also deployed at T1.

  6. Seventeen-year systematic measurements of dust aerosol optical properties using the eole ntua lidar system (2000-2016)

    NASA Astrophysics Data System (ADS)

    Soupiona, Ourania; Mylonaki, Maria; Papayannis, Alexandros; Argyrouli, Athina; Kokkalis, Panayotis; Tsaknakis, Georgios

    2018-04-01

    A comprehensive analysis of the seasonal variability of the optical properties of Saharan dust aerosols over Athens, Greece, is presented for a 17-year time period (2000-2016), as derived from multi-wavelength Raman lidar measurements (57 dust events with more than 80 hours of measurements). The profiles of the derived aerosol optical properties (aerosol backscatter and extinction coefficients, lidar ratio and aerosol Ångström exponent) at 355 nm are presented. For these dust events we found a mean value of the lidar ratio of 52±13 sr at 355 nm and of 58±8 sr (not shown) at 532 nm (2-4 km a.s.l. height). For our statistical analysis, presented here, we used monthly-mean values and time periods under cloud-free conditions. The number of dust events was greatest in late spring, summer, and early autumn periods. In this paper we also present a selected case study (04 April 2016) of desert dust long-range transport from the Saharan desert.

  7. Optimal estimation retrieval of aerosol microphysical properties from SAGE~II satellite observations in the volcanically unperturbed lower stratosphere

    NASA Astrophysics Data System (ADS)

    Wurl, D.; Grainger, R. G.; McDonald, A. J.; Deshler, T.

    2010-05-01

    Stratospheric aerosol particles under non-volcanic conditions are typically smaller than 0.1 μm. Due to fundamental limitations of the scattering theory in the Rayleigh limit, these tiny particles are hard to measure by satellite instruments. As a consequence, current estimates of global aerosol properties retrieved from spectral aerosol extinction measurements tend to be strongly biased. Aerosol surface area densities, for instance, are observed to be about 40% smaller than those derived from correlative in situ measurements (Deshler et al., 2003). An accurate knowledge of the global distribution of aerosol properties is, however, essential to better understand and quantify the role they play in atmospheric chemistry, dynamics, radiation and climate. To address this need a new retrieval algorithm was developed, which employs a nonlinear Optimal Estimation (OE) method to iteratively solve for the monomodal size distribution parameters which are statistically most consistent with both the satellite-measured multi-wavelength aerosol extinction data and a priori information. By thus combining spectral extinction measurements (at visible to near infrared wavelengths) with prior knowledge of aerosol properties at background level, even the smallest particles are taken into account which are practically invisible to optical remote sensing instruments. The performance of the OE retrieval algorithm was assessed based on synthetic spectral extinction data generated from both monomodal and small-mode-dominant bimodal sulphuric acid aerosol size distributions. For monomodal background aerosol, the new algorithm was shown to fairly accurately retrieve the particle sizes and associated integrated properties (surface area and volume densities), even in the presence of large extinction uncertainty. The associated retrieved uncertainties are a good estimate of the true errors. In the case of bimodal background aerosol, where the retrieved (monomodal) size distributions naturally

  8. Long term aerosol and trace gas measurements in Central Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

    2016-04-01

    The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

  9. Elevated aerosol layers modify the O2–O2 absorption measured by ground-based MAX-DOAS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ortega, Ivan; Berg, Larry K.; Ferrare, Richard A.

    2016-06-01

    The oxygen collisional complex (O2-O2, or O4) is a greenhouse gas, and a calibration trace gas used to infer aerosol and cloud properties by Differential Optical Absorption Spectroscopy (DOAS). Recent reports suggest the need for an O4 correction factor (CFO4) when comparing simulated and measured O4 differential slant column densities (dSCD) by passive DOAS. We investigate the sensitivity of O4 dSCD simulations at ultraviolet (360 nm) and visible (477 nm) wavelengths towards separately measured aerosol extinction profiles. Measurements were conducted by the University of Colorado 2D-MAX-DOAS instrument and NASA’s multispectral High Spectral Resolution Lidar (HSRL-2) during the Two Column Aerosolmore » Project (TCAP) at Cape Cod, MA in July 2012. During two case study days with (1) high aerosol load (17 July, AOD ~ 0.35 at 477 nm), and (2) near molecular scattering conditions (22 July, AOD < 0.10 at 477 nm) the measured and calculated O4 dSCDs agreed within 6.4±0.4% (360 nm) and 4.7±0.6% (477 nm) if the HSRL-2 profiles were used as input to the calculations. However, if in the calculations the aerosol is confined to the surface layer (while keeping AOD constant) we find 0.53« less

  10. The Cretaceous-Tertiary extinction: A lethal mechanism involving anhydrite target rocks

    USGS Publications Warehouse

    Brett, R.

    1992-01-01

    The Chicxulub Crater, Yucatan, Mexico, is a leading contender as the site for the impact event that caused the Cretaceous-Tertiary (K-T) extinctions. A considerable thickness of anhydrite (CaSO4) forms part of the target rock. High temperatures resulting from impact would drive SO2 off from the anhydrite. Hundreds of billions of tonnes of sulfuric acid aerosol would thus enter the stratosphere and cause considerable cooling of the Earth's surface, decrease photosynthesis by orders of magnitude, deplete the ozone layer, and permit increased UV radiation to reach the Earth's surface. Finally, the aerosol would fall back to Earth as acid rain and devastate land and some lacustrine biota and near-surface marine creatures. The presence of anhydrite in the Chicxulub target rock may thus help explain the many extinctions observed at the K-T boundary. ?? 1992.

  11. Long-term systematic profiling of dust aerosol optical properties using the EOLE NTUA lidar system over Athens, Greece (2000-2016)

    NASA Astrophysics Data System (ADS)

    Soupiona, O.; Papayannis, A.; Kokkalis, P.; Mylonaki, M.; Tsaknakis, G.; Argyrouli, A.; Vratolis, S.

    2018-06-01

    We present a comprehensive analysis of the seasonal variability of the vertical profiles of the optical and geometrical properties of Saharan dust aerosols, observed in the height region between 1000 and 6000 m, over the city of Athens, Greece, from February 2000 to December 2016. These observations were performed by a multi-wavelength (355-387-532-1064 nm) Raman lidar system under cloud-free conditions. The statistical analysis (using aerosol monthly mean values) is based on nighttime vertical Raman measurements of range-resolved aerosol optical properties (backscatter and extinction coefficients, lidar ratio, Ångström exponent) at 355 nm (57 dust events during more than 80 measurement hours). We found that the number of dust events was highest in spring, summer, and early autumn periods and that during spring the dust layers were moved at higher altitudes (∼4500 m) than in other seasons. The number of the forecasted dusty days (on monthly basis) by the BSC-DREAM8b model compared to those of the performed lidar measurements were found to have a quite strong correlation (R2 = 0.81), with a maximum occurrence predicted for the spring season. In the worst case scenario, at least 50% of the model-forecasted dust events can be observed by lidar under cloudless skies over Athens. For the sampled dust plumes we found mean lidar ratios of 52 ± 13 sr at 355 nm in the height range 2000-4000 m a.s.l. Moreover, the dust layers had a mean thickness of 2497 ± 1026 m and a center of mass of 2699 ± 1017 m. An analysis performed regarding the air mass back-trajectories arriving over Athens revealed two main clusters: one pathway from south-west to north-east, with dust emission areas in Tunisia, Algeria and Libya and a second one from south, across the Mediterranean Sea with emission areas over Libya and the remaining part of Algeria and Tunisia. This clustering enabled us to differentiate between the aerosol optical properties between the two clusters, based on their

  12. Extinction effects of atmospheric compositions on return signals of space-based lidar from numerical simulation

    NASA Astrophysics Data System (ADS)

    Yao, Lilin; Wang, Fu; Min, Min; Zhang, Ying; Guo, Jianping; Yu, Xiao; Chen, Binglong; Zhao, Yiming; Wang, Lidong

    2018-05-01

    The atmospheric composition induced extinction effect on return signals of space-based lidar remains incomprehensively understood, especially around 355 nm and 2051 nm channels. Here we simulated the extinction effects of atmospheric gases (e.g., H2O, CO2, and O3) and six types of aerosols (clean continental, clean marine, dust, polluted continental, polluted dust, and smoke) on return signals of space-based lidar system at 355 nm, 532 nm, 1064 nm, and 2051 nm channels, based on a robust lidar return signal simulator in combination with radiative transfer model (LBLRTM). Results show significant Rayleigh (molecular) scattering effects in the return signals at 355 nm and 532 nm channels, which markedly decays with increases in wavelength. The spectral transmittance of CO2 is nearly 0, yet the transmittance of H2O is approximately 100% at 2051 nm, which verifies this 2051 nm channel is suitable for CO2 retrieval. The spectral transmittance also reveals another possible window for CO2 and H2O detection at 2051.6 nm, since their transmittance both near 0.5. Moreover the corresponding Doppler return signals at 2051.6 nm channel can be used to retrieve wind field. Thus we suggest 2051 nm channel may better be centered at 2051.6 nm. Using the threshold for the signal-to-noise ratio (SNR) of return signals, the detection ranges for three representative distribution scenarios for the six types of aerosols at four typical lidar channels are determined. The results clearly show that high SNR values can be seen ubiquitously in the atmosphere ranging from the height of aerosol layer top to 25 km at 355 nm, and can been found at 2051.6 nm in the lower troposphere that highly depends on aerosol distribution scenario in the vertical. This indicates that the Doppler space-based lidar system with a double-channel joint detection mode is able to retrieve atmospheric wind field or profile from 0 to 25 km.

  13. Observations of particle extinction, PM2.5 mass concentration profile and flux in north China based on mobile lidar technique

    NASA Astrophysics Data System (ADS)

    Lv, Lihui; Liu, Wenqing; Zhang, Tianshu; Chen, Zhenyi; Dong, Yunsheng; Fan, Guangqiang; Xiang, Yan; Yao, Yawei; Yang, Nan; Chu, Baolin; Teng, Man; Shu, Xiaowen

    2017-09-01

    Fine particle with diameter <2.5 μm (PM2.5) have important direct and indirect effects on human life and activities. However, the studies of fine particle were limited by the lack of monitoring data obtained with multiple fixed site sampling strategies. Mobile monitoring has provided a means for broad measurement of fine particles. In this research, the potential use of mobile lidar to map the distribution and transport of fine particles was discussed. The spatial and temporal distributions of particle extinction, PM2.5 mass concentration and regional transport flux of fine particle in the planetary boundary layer were investigated with the use of vehicle-based mobile lidar and wind field data from north China. Case studies under different pollution levels in Beijing were presented to evaluate the contribution of regional transport. A vehicle-based mobile lidar system was used to obtain the spatial and temporal distributions of particle extinction in the measurement route. Fixed point lidar and a particulate matter sampler were operated next to each other at the University of Chinese Academy of Science (UCAS) in Beijing to determine the relationship between the particle extinction coefficient and PM2.5 mass concentration. The correlation coefficient (R2) between the particle extinction coefficient and PM2.5 mass concentration was found to be over 0.8 when relative humidity (RH) was less than 90%. A mesoscale meteorological model, the Weather Research and Forecasting (WRF) model, was used to obtain profiles of the horizontal wind speed, wind direction and relative humidity. A vehicle-based mobile lidar technique was applied to estimate transport flux based on the PM2.5 profile and vertical profile of wind data. This method was applicable when hygroscopic growth can be neglected (relatively humidity<90%). Southwest was found to be the main pathway of Beijing during the experiments.

  14. Inversion of the anomalous diffraction approximation for variable complex index of refraction near unity. [numerical tests for water-haze aerosol model

    NASA Technical Reports Server (NTRS)

    Smith, C. B.

    1982-01-01

    The Fymat analytic inversion method for retrieving a particle-area distribution function from anomalous diffraction multispectral extinction data and total area is generalized to the case of a variable complex refractive index m(lambda) near unity depending on spectral wavelength lambda. Inversion tests are presented for a water-haze aerosol model. An upper-phase shift limit of 5 pi/2 retrieved an accurate peak area distribution profile. Analytical corrections using both the total number and area improved the inversion.

  15. Elevated Aerosol Layers and Their Radiative Impact over Kanpur During Monsoon Onset Period

    NASA Technical Reports Server (NTRS)

    Sarangi, Chandan; Tripathi, S. N.; Mishra, A. K.; Welton, E. J.

    2016-01-01

    Accurate information about aerosol vertical distribution is needed to reduce uncertainties in aerosol radiative forcing and its effect on atmospheric dynamics. The present study deals with synergistic analyses of aerosol vertical distribution and aerosol optical depth (AOD) with meteorological variables using multisatellite and ground-based remote sensors over Kanpur in central Indo-Gangetic Plain (IGP). Micro-Pulse Lidar Network-derived aerosol vertical extinction (sigma) profiles are analyzed to quantify the interannual and daytime variations during monsoon onset period (May-June) for 2009-2011. The mean aerosol profile is broadly categorized into two layers viz., a surface layer (SL) extending up to 1.5 km (where sigma decreased exponentially with height) and an elevated aerosol layer (EAL) extending between 1.5 and 5.5 km. The increase in total columnar aerosol loading is associated with relatively higher increase in contribution from EAL loading than that from SL. The mean contributions of EALs are about 60%, 51%, and 50% to total columnar AOD during 2009, 2010, and 2011, respectively. We observe distinct parabolic EALs during early morning and late evening but uniformly mixed EALs during midday. The interannual and daytime variations of EALs are mainly influenced by long-range transport and convective capacity of the local emissions, respectively. Radiative flux analysis shows that clear-sky incoming solar radiation at surface is reduced with increase in AOD, which indicates significant cooling at surface. Collocated analysis of atmospheric temperature and aerosol loading reveals that increase in AOD not only resulted in surface dimming but also reduced the temperature (approximately 2-3 C) of lower troposphere (below 3 km altitude). Radiative transfer simulations indicate that the reduction of incoming solar radiation at surface is mainly due to increased absorption by EALs (with increase in total AOD). The observed cooling in lower troposphere in high

  16. Aerosol optical properties in the southeastern United States in summer - Part 1: Hygroscopic growth

    NASA Astrophysics Data System (ADS)

    Brock, Charles A.; Wagner, Nicholas L.; Anderson, Bruce E.; Attwood, Alexis R.; Beyersdorf, Andreas; Campuzano-Jost, Pedro; Carlton, Annmarie G.; Day, Douglas A.; Diskin, Glenn S.; Gordon, Timothy D.; Jimenez, Jose L.; Lack, Daniel A.; Liao, Jin; Markovic, Milos Z.; Middlebrook, Ann M.; Ng, Nga L.; Perring, Anne E.; Richardson, Matthews S.; Schwarz, Joshua P.; Washenfelder, Rebecca A.; Welti, Andre; Xu, Lu; Ziemba, Luke D.; Murphy, Daniel M.

    2016-04-01

    Aircraft observations of meteorological, trace gas, and aerosol properties were made during May-September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at relative humidities (RHs) of ˜ 15, ˜ 70, and ˜ 90 % and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at ˜ 90 % RH. The dominance of organic aerosol, which comprised 65 ± 10 % of particulate matter with aerodynamic diameter < 1 µm in the planetary boundary layer, resulted in relatively low f(RH) values of 1.43 ± 0.67 at 70 % RH and 2.28 ± 1.05 at 90 % RH. The subsaturated κ-Köhler hygroscopicity parameter κ for the organic fraction of the aerosol must have been < 0.10 to be consistent with 75 % of the observations within uncertainties, with a best estimate of κ = 0.05. This subsaturated κ value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation.

  17. Extracting atmospheric turbulence and aerosol characteristics from passive imagery

    NASA Astrophysics Data System (ADS)

    Reinhardt, Colin N.; Wayne, D.; McBryde, K.; Cauble, G.

    2013-09-01

    Obtaining accurate, precise and timely information about the local atmospheric turbulence and extinction conditions and aerosol/particulate content remains a difficult problem with incomplete solutions. It has important applications in areas such as optical and IR free-space communications, imaging systems performance, and the propagation of directed energy. The capability to utilize passive imaging data to extract parameters characterizing atmospheric turbulence and aerosol/particulate conditions would represent a valuable addition to the current piecemeal toolset for atmospheric sensing. Our research investigates an application of fundamental results from optical turbulence theory and aerosol extinction theory combined with recent advances in image-quality-metrics (IQM) and image-quality-assessment (IQA) methods. We have developed an algorithm which extracts important parameters used for characterizing atmospheric turbulence and extinction along the propagation channel, such as the refractive-index structure parameter C2n , the Fried atmospheric coherence width r0 , and the atmospheric extinction coefficient βext , from passive image data. We will analyze the algorithm performance using simulations based on modeling with turbulence modulation transfer functions. An experimental field campaign was organized and data were collected from passive imaging through turbulence of Siemens star resolution targets over several short littoral paths in Point Loma, San Diego, under conditions various turbulence intensities. We present initial results of the algorithm's effectiveness using this field data and compare against measurements taken concurrently with other standard atmospheric characterization equipment. We also discuss some of the challenges encountered with the algorithm, tasks currently in progress, and approaches planned for improving the performance in the near future.

  18. Transport of Aerosols from Asia and Their Radiative Effects Over the Western Pacific: A 3-D Model Study for ACE-Asia Experiment During Spring 2001

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Flatau, Piotr; Anderson, Tad; Masonis, Sarah; Russell, Phil; Schmid, Beat; Livingston, John; Redemann, Jens; Kahn, Ralph; hide

    2001-01-01

    The Aerosol Characterization Experiment-Asia (ACE-Asia) took place in Spring 2001 in the East Asia-West Pacific Ocean. During the ACE-Asia intensive field operation period, high concentrations of dust and anthropogenic aerosols were observed over the Yellow Sea and the Sea of Japan, which were transported out from the Asian continent, with the plume often extending to 6-8 km altitude. The multi-component aerosols originated from Asia are expected to exert a significant radiative forcing over the Pacific region. We present here results from the Georgia Tech/Goddard Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) model of aerosol transport and radiative forcing in the context of ACE-Asia. The model calculated aerosol concentrations, extinctions, optical thickness, size distributions, and vertical profiles are compared with the aircraft and ship measurements, and the distributions of aerosols are compared with satellite data. The model will be used to understand the origins of the aerosols observed in ACE-Asia, estimate the contributions from anthropogenic and natural aerosols to the total aerosol optical thickness, investigate the effects of humidification and clouds on aerosol properties, and assess the radiative forcing of Asian aerosols over the Pacific region and in the northern hemisphere.

  19. Evaluation of the operational Aerosol Layer Height retrieval algorithm for Sentinel-5 Precursor: application to O2 A band observations from GOME-2A

    NASA Astrophysics Data System (ADS)

    Sanders, A. F. J.; de Haan, J. F.; Sneep, M.; Apituley, A.; Stammes, P.; Vieitez, M. O.; Tilstra, L. G.; Tuinder, O. N. E.; Koning, C. E.; Veefkind, J. P.

    2015-06-01

    An algorithm setup for the operational Aerosol Layer Height product for TROPOMI on the Sentinel-5 Precursor mission is described and discussed, applied to GOME-2A data, and evaluated with lidar measurements. The algorithm makes a spectral fit of reflectance at the O2 A band in the near-infrared and the fit window runs from 758 to 770 nm. The aerosol profile is parameterized by a scattering layer with constant aerosol volume extinction coefficient and aerosol single scattering albedo and with a fixed pressure thickness. The algorithm's target parameter is the height of this layer. In this paper, we apply the algorithm to observations from GOME-2A in a number of systematic and extensive case studies and we compare retrieved aerosol layer heights with lidar measurements. Aerosol scenes cover various aerosol types, both elevated and boundary layer aerosols, and land and sea surfaces. The aerosol optical thicknesses for these scenes are relatively moderate. Retrieval experiments with GOME-2A spectra are used to investigate various sensitivities, in which particular attention is given to the role of the surface albedo. From retrieval simulations with the single-layer model, we learn that the surface albedo should be a fit parameter when retrieving aerosol layer height from the O2 A band. Current uncertainties in surface albedo climatologies cause biases and non-convergences when the surface albedo is fixed in the retrieval. Biases disappear and convergence improves when the surface albedo is fitted, while precision of retrieved aerosol layer pressure is still largely within requirement levels. Moreover, we show that fitting the surface albedo helps to ameliorate biases in retrieved aerosol layer height when the assumed aerosol model is inaccurate. Subsequent retrievals with GOME-2A spectra confirm that convergence is better when the surface albedo is retrieved simultaneously with aerosol parameters. However, retrieved aerosol layer pressures are systematically low (i

  20. Evaluation of the operational Aerosol Layer Height retrieval algorithm for Sentinel-5 Precursor: application to O2 A band observations from GOME-2A

    NASA Astrophysics Data System (ADS)

    Sanders, A. F. J.; de Haan, J. F.; Sneep, M.; Apituley, A.; Stammes, P.; Vieitez, M. O.; Tilstra, L. G.; Tuinder, O. N. E.; Koning, C. E.; Veefkind, J. P.

    2015-11-01

    An algorithm setup for the operational Aerosol Layer Height product for TROPOMI on the Sentinel-5 Precursor mission is described and discussed, applied to GOME-2A data, and evaluated with lidar measurements. The algorithm makes a spectral fit of reflectance at the O2 A band in the near-infrared and the fit window runs from 758 to 770 nm. The aerosol profile is parameterised by a scattering layer with constant aerosol volume extinction coefficient and aerosol single scattering albedo and with a fixed pressure thickness. The algorithm's target parameter is the height of this layer. In this paper, we apply the algorithm to observations from GOME-2A in a number of systematic and extensive case studies, and we compare retrieved aerosol layer heights with lidar measurements. Aerosol scenes cover various aerosol types, both elevated and boundary layer aerosols, and land and sea surfaces. The aerosol optical thicknesses for these scenes are relatively moderate. Retrieval experiments with GOME-2A spectra are used to investigate various sensitivities, in which particular attention is given to the role of the surface albedo. From retrieval simulations with the single-layer model, we learn that the surface albedo should be a fit parameter when retrieving aerosol layer height from the O2 A band. Current uncertainties in surface albedo climatologies cause biases and non-convergences when the surface albedo is fixed in the retrieval. Biases disappear and convergence improves when the surface albedo is fitted, while precision of retrieved aerosol layer pressure is still largely within requirement levels. Moreover, we show that fitting the surface albedo helps to ameliorate biases in retrieved aerosol layer height when the assumed aerosol model is inaccurate. Subsequent retrievals with GOME-2A spectra confirm that convergence is better when the surface albedo is retrieved simultaneously with aerosol parameters. However, retrieved aerosol layer pressures are systematically low (i

  1. Determination of the aerosol size distribution by analytic inversion of the extinction spectrum in the complex anomalous diffraction approximation.

    PubMed

    Franssens, G; De Maziére, M; Fonteyn, D

    2000-08-20

    A new derivation is presented for the analytical inversion of aerosol spectral extinction data to size distributions. It is based on the complex analytic extension of the anomalous diffraction approximation (ADA). We derive inverse formulas that are applicable to homogeneous nonabsorbing and absorbing spherical particles. Our method simplifies, generalizes, and unifies a number of results obtained previously in the literature. In particular, we clarify the connection between the ADA transform and the Fourier and Laplace transforms. Also, the effect of the particle refractive-index dispersion on the inversion is examined. It is shown that, when Lorentz's model is used for this dispersion, the continuous ADA inverse transform is mathematically well posed, whereas with a constant refractive index it is ill posed. Further, a condition is given, in terms of Lorentz parameters, for which the continuous inverse operator does not amplify the error.

  2. Retrieval of Aerosol Parameters from Continuous H24 Lidar-Ceilometer Measurements

    NASA Astrophysics Data System (ADS)

    Dionisi, D.; Barnaba, F.; Costabile, F.; Di Liberto, L.; Gobbi, G. P.; Wille, H.

    2016-06-01

    Ceilometer technology is increasingly applied to the monitoring and the characterization of tropospheric aerosols. In this work, a method to estimate some key aerosol parameters (extinction coefficient, surface area concentration and volume concentration) from ceilometer measurements is presented. A numerical model has been set up to derive a mean functional relationships between backscatter and the above mentioned parameters based on a large set of simulated aerosol optical properties. A good agreement was found between the modeled backscatter and extinction coefficients and the ones measured by the EARLINET Raman lidars. The developed methodology has then been applied to the measurements acquired by a prototype Polarization Lidar-Ceilometer (PLC). This PLC instrument was developed within the EC- LIFE+ project "DIAPASON" as an upgrade of the commercial, single-channel Jenoptik CHM15k system. The PLC run continuously (h24) close to Rome (Italy) for a whole year (2013-2014). Retrievals of the aerosol backscatter coefficient at 1064 nm and of the relevant aerosol properties were performed using the proposed methodology. This information, coupled to some key aerosol type identification made possible by the depolarization channel, allowed a year-round characterization of the aerosol field at this site. Examples are given to show how this technology coupled to appropriate data inversion methods is potentially useful in the operational monitoring of parameters of air quality and meteorological interest.

  3. Aerosol optical properties measurements by a CAPS single scattering albedo monitor: Comparisons between summer and winter in Beijing, China

    NASA Astrophysics Data System (ADS)

    Han, Tingting; Xu, Weiqi; Li, Jie; Freedman, Andrew; Zhao, Jian; Wang, Qingqing; Chen, Chen; Zhang, Yingjie; Wang, Zifa; Fu, Pingqing; Liu, Xingang; Sun, Yele

    2017-02-01

    Aerosol optical properties were measured in Beijing in summer and winter using a state-of-the-art cavity attenuated phase shift single scattering albedo monitor (CAPS PMssa) along with aerosol composition measurements by aerosol mass spectrometers and aethalometers. The SSA directly measured by the CAPS PMssa showed overall agreements with those derived from colocated measurements. However, substantial differences were observed during periods with low SSA values in both summer and winter, suggesting that interpretation of low SSA values needs to be cautious. The average (±σ) extinction coefficient (bext) and absorption coefficient (bap) were 336 (±343) Mm-1 and 44 (±41) Mm-1, respectively, during wintertime, which were approximately twice those observed in summer, while the average SSA was relatively similar, 0.86 (±0.06) and 0.85 (±0.04) in summer and winter, respectively. Further analysis showed that the variations in SSA can be approximately parameterized as a function of mass fraction of secondary particulate matter (fSPM), which is SSA = 0.74 + 0.19 × fSPM (fSPM > 0.3, r2 = 0.85). The contributions of aerosol species to extinction coefficients during the two seasons were also estimated. Our results showed that the light extinction was dominantly contributed by ammonium sulfate (30%) and secondary organic aerosol (22%) in summer, while organic aerosol was the largest contributor (51%) in winter. Consistently, SPM played the major role in visibility degradation in both seasons by contributing 70% of the total extinction.

  4. Light Source Effects on Aerosol Photoacoustic Spectroscopy Measurements

    PubMed Central

    Radney, James G.; Zangmeister, Christopher D.

    2016-01-01

    Photoacoustic spectroscopy measurements of flame-generated soot aerosol coated with small amounts of water yielded absorption enhancements that were dependent on the laser used: quasi-continuous wave (Q-CW, ≈ 650 ps pulse duration and 78 MHz repetition rate) versus continuous wave (CW). Water coating thickness was controlled by exposing the aerosol to a set relative humidity (RH). At ≈ 85 % RH, the mass of the soot particles increased by an amount comparable to a monolayer of water being deposited and enhanced the measured absorption by 36 % and 15 % for the Q-CW and CW lasers, respectively. Extinction measurements were also performed using a cavity ring-down spectrometer (extinction equals the sum of absorption and scattering) with a CW laser and negligible enhancement was observed at all RH. These findings demonstrate that source choice can impact measurements of aerosols with volatile coatings and that the absorption enhancements at high RH previously measured by Radney and Zangmeister (2015) [1] are the result of laser source used (Q-CW) and not from an increase in the particle absorption cross section. PMID:28066027

  5. How much of the global aerosol optical depth is found in the boundary layer and free troposphere?

    NASA Astrophysics Data System (ADS)

    Bourgeois, Quentin; Ekman, Annica M. L.; Renard, Jean-Baptiste; Krejci, Radovan; Devasthale, Abhay; Bender, Frida A.-M.; Riipinen, Ilona; Berthet, Gwenaël; Tackett, Jason L.

    2018-06-01

    The global aerosol extinction from the CALIOP space lidar was used to compute aerosol optical depth (AOD) over a 9-year period (2007-2015) and partitioned between the boundary layer (BL) and the free troposphere (FT) using BL heights obtained from the ERA-Interim archive. The results show that the vertical distribution of AOD does not follow the diurnal cycle of the BL but remains similar between day and night highlighting the presence of a residual layer during night. The BL and FT contribute 69 and 31 %, respectively, to the global tropospheric AOD during daytime in line with observations obtained in Aire sur l'Adour (France) using the Light Optical Aerosol Counter (LOAC) instrument. The FT AOD contribution is larger in the tropics than at mid-latitudes which indicates that convective transport largely controls the vertical profile of aerosols. Over oceans, the FT AOD contribution is mainly governed by long-range transport of aerosols from emission sources located within neighboring continents. According to the CALIOP aerosol classification, dust and smoke particles are the main aerosol types transported into the FT. Overall, the study shows that the fraction of AOD in the FT - and thus potentially located above low-level clouds - is substantial and deserves more attention when evaluating the radiative effect of aerosols in climate models. More generally, the results have implications for processes determining the overall budgets, sources, sinks and transport of aerosol particles and their description in atmospheric models.

  6. Aircraft- and ground-based assessment of the CCN-AOD relationship and implications on model analysis of ACI and underlying aerosol processes

    NASA Astrophysics Data System (ADS)

    Shinozuka, Y.; Clarke, A. D.; Nenes, A.; Lathem, T. L.; Redemann, J.; Jefferson, A.; Wood, R.

    2014-12-01

    Contrary to common assumptions in satellite-based modeling of aerosol-cloud interactions, ∂logCCN/∂logAOD is less than unity, i.e., the number concentration of cloud condensation nuclei (CCN) less than doubles as aerosol optical depth (AOD) doubles. This can be explained by omnipresent aerosol processes. Condensation, coagulation and cloud processing, for example, generally make particles scatter more light while hardly increasing their number. This paper reports on the relationship in local air masses between CCN concentration, aerosol size distribution and light extinction observed from aircraft and the ground at diverse locations. The CCN-to-local-extinction relationship, when averaged over ~1 km distance and sorted by the wavelength dependence of extinction, varies approximately by a factor of 2, reflecting the variability in aerosol intensive properties. This, together with retrieval uncertainties and the variability in aerosol spatio-temporal distribution and hygroscopic growth, challenges satellite-based CCN estimates. However, the large differences in estimated CCN may correspond to a considerably lower uncertainty in cloud drop number concentration (CDNC), given the sublinear response of CDNC to CCN. Overall, our findings from airborne and ground-based observations call for model-based reexamination of aerosol-cloud interactions and underlying aerosol processes.

  7. Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

    NASA Astrophysics Data System (ADS)

    Brown, S. S.; Dubé, W. P.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Warneke, C.; de Gouw, J. A.; Washenfelder, R. A.; Atlas, E.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Schwarz, J. P.; Spackman, R.; Trainer, M.; Parrish, D. D.; Fehshenfeld, F. C.; Ravishankara, A. R.

    2013-11-01

    Organic compounds are a large component of aerosol mass, but organic aerosol (OA) sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter category serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within the nocturnal boundary layer (NBL), which varied in depth from 100-400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2-2.7 ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1 ppbv h-1), mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Some profiles may have been influenced by biomass burning sources as well, making quantitative attribution of organic aerosol sources difficult. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m-3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m-3.

  8. Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDE

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Redemann, Jens; Russell, Philip; Schmid, Beat; Reid, Jeff; Pilewskie, Peter; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident

  9. Severe environmental effects of Chicxulub impact imply key role in end-Cretaceous mass extinction

    NASA Astrophysics Data System (ADS)

    Brugger, Julia; Feulner, Georg; Petri, Stefan

    2017-04-01

    66 million years ago, during the most recent of the five severe mass extinctions in Earth's history, non-avian dinosaurs and many other organisms became extinct. The cause of this end-Cretaceous mass extinction is seen in either flood-basalt eruptions or an asteroid impact. Modeling the climatic changes after the Chicxulub asteroid impact allow to assess its contribution to the extinction event and to analyze the short-term and long-term response of the climate and the biosphere to the impact. Existing studies either investigated the effect of dust, which is now believed to play a minor role, or used one-dimensional, non-coupled models. In contrast, we use a coupled climate model to explore the longer lasting cooling due to sulfate aerosols. Based on data from geophysical impact modeling, we set up simulations with different stratospheric residence times for sulfate aerosols. Depending on this residence time, global surface air temperature decreased by at least 26°C, with 3 to 16 years subfreezing temperatures and a recovery time larger than 30 years. Vigorous ocean mixing, caused by the fast cooling of the surface ocean, might have perturbed marine ecosystems by the upwelling of nutrients. The dramatic climatic changes seen in our simulations imply severe environmental effects and therefore a significant contribution of the impact in the end-Cretaceous mass extinction.

  10. Comparison of MAX-DOAS profiling algorithms during CINDI-2 - Part 2: trace gases

    NASA Astrophysics Data System (ADS)

    Hendrick, Francois; Friess, Udo; Tirpitz, Lukas; Apituley, Arnoud; Van Roozendael, Michel; Kreher, Karin; Richter, Andreas; Wagner, Thomas

    2017-04-01

    The second Cabauw Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI-2) took place at the Cabauw Experimental Site for Atmospheric Research (CESAR; Utrecht area, The Netherlands) from 25 August until 7 October 2016. CINDI-2 was aiming at assessing the consistency of MAX-DOAS slant column density measurements of tropospheric species (NO2, HCHO, O3, and O4) relevant for the validation of future ESA atmospheric Sentinel missions, through coordinated operation of a large number of DOAS and MAXDOAS instruments from all over the world. An important objective of the campaign was to study the relationship between remote-sensing column and profile measurements of the above species and collocated reference ancillary observations. For this purpose, the CINDI-2 Profiling Task Team (CPTT) was created, involving 22 groups performing aerosol and trace gas vertical profile inversion using dedicated MAX-DOAS profiling algorithms, as well as the teams responsible for ancillary profile and surface concentration measurements (NO2 analysers, NO2 sondes, NO2 and Raman LIDARs, CAPS, Long-Path DOAS, sunphotometer, nephelometer, etc). The main purpose of the CPTT is to assess the consistency of the different profiling tools for retrieving aerosol extinction and trace gas vertical profiles through comparison exercises using commonly defined settings and to validate the retrievals with correlative observations. In this presentation, we give an overview of the MAX-DOAS vertical profile comparison results, focusing on NO2 and HCHO, the aerosol retrievals being presented in a companion abstract led by U. Frieß. The performance of the different algorithms is investigated with respect to the various sky and weather conditions and aerosol loadings encountered during the campaign. The consistency between optimal-estimation-based and parameterized profiling tools is also evaluated for these different conditions, together with the level of agreement with available NO2 and

  11. An Evaluation of the Naval Oceanic Vertical Aerosol Model During Key90

    DTIC Science & Technology

    1991-06-01

    regions with extensive aerosol content (such as were caused by the intentional burning of oil rigs). Many military devices operate in the visible to...that aerosol extinction above the second inversion is essentil y zero when the air mass parameter is calculated to be approximately equal to one do : s

  12. Aerosol profiling with lidar in the Amazon Basin during the wet and dry season

    NASA Astrophysics Data System (ADS)

    Baars, H.; Ansmann, A.; Althausen, D.; Engelmann, R.; Heese, B.; Müller, D.; Artaxo, P.; Paixao, M.; Pauliquevis, T.; Souza, R.

    2012-11-01

    For the first time, multiwavelength polarization Raman lidar observations of optical and microphysical particle properties over the Amazon Basin are presented. The fully automated advanced Raman lidar was deployed 60 km north of Manaus, Brazil (2.5°S, 60°W) in the Amazon rain forest from January to November 2008. The measurements thus cover both the wet season (Dec-June) and the dry or burning season (July-Nov). Two cases studies of young and aged smoke plumes are discussed in terms of spectrally resolved optical properties (355, 532, and 1064 nm) and further lidar products such as particle effective radius and single-scattering albedo. These measurement examples confirm that biomass burning aerosols show a broad spectrum of optical, microphysical, and chemical properties. The statistical analysis of the entire measurement period revealed strong differences between the pristine wet and the polluted dry season. African smoke and dust advection frequently interrupt the pristine phases during the wet season. Compared to pristine wet season conditions, the particle scattering coefficients in the lowermost 2 km of the atmosphere were found to be enhanced, on average, by a factor of 4 during periods of African aerosol intrusion and by a factor of 6 during the dry (burning) season. Under pristine conditions, the particle extinction coefficients and optical depth for 532 nm wavelength were frequently as low as 10-30 Mm-1 and <0.05, respectively. During the dry season, biomass burning smoke plumes reached to 3-5 km height and caused a mean optical depth at 532 nm of 0.26. On average during that season, particle extinction coefficients (532 nm) were of the order of 100 Mm-1 in the main pollution layer (up to 2 km height). Ångström exponents were mainly between 1.0 and 1.5, and the majority of the observed lidar ratios were between 50-80 sr.

  13. Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Under funding from this proposal we evaluated measurements of stratospheric sulfate aerosols from three platforms. Two were satellite platforms providing solar extinction measurements, the Stratospheric Aerosol and Gas Experiment (SAGE) II using wavelengths from 0.386 - 1.02 microns, and the Halogen Occultation Experiment (HALOE) using wavelengths from 2.45 to 5.26 microns. The third set of measurements was from in situ sampling by balloonborne optical particle counters (OPCs). The goal was to determine the consistency among these data sets. This was accomplished through analysis of the existing measurement records, and through additional balloonborne OPC flights coinciding with new SAGE II observations over Laramie, Wyoming. All analyses used the SAGE II v 6.0 data. This project supported two balloon flights per year over Laramie dedicated to SAGE II coincidence. Because logistical factors, such as poor surface weather or unfavorable payload impact location, can make it difficult to routinely obtain close coincidences with SAGE II, we attempt to conduct nearly every Laramie flight (roughly one per month) in conjunction with a SAGE II overpass. The Laramie flight frequency has varied over the years depending on field commitments and funding sources. Current support for the Laramie measurements is from the National Science Foundation in addition to support from this NASA grant. We have also completed a variety of comparisons using aerosol measurements from SAGE II, OPCs, and HALOE. The instruments were compared for their various estimates of aerosol extinction at the SAGE II wavelengths and for aerosol surface area. Additional results, such as illustrated here, can be found in a recently accepted manuscript describing comparisons between SAGE II, HALOE, and OPCs for the period 1982 - 2000. While overall, the impression from these results is encouraging, the agreement of the measurements changes with latitude, altitude, time, and parameter. In the broadest sense

  14. The Micro-Pulse Lidar Network (MPLNET): A Federated Network of Micro-pulse Lidars and AERONET Sunphotometers

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Spinhirne, James D.; Berkoff, Timothy A.; Holben, Brent; Tsay, Si-Chee

    2004-01-01

    We present the formation of a new global-ground based eye-safe lidar network, the NASA Micro-Pulse Lidar Network (MPLNET). The aim of MPLNET is to acquire long- term observations of aerosol and cloud vertical profiles at unique geographic sites within the NASA Aerosol Robotic Network (AERONET). MPLNET utilizes standard instrumentation and data processing algorithms for efficient network operations and direct comparison of data between each site. The micro-pulse lidar is eye-safe, compact, and commercially available, and most easily allows growth of the network without sacrificing standardized instrumentation goals. Network growth follows a federated approach, pioneered by AERONET, wherein independent research groups may join MPLNET with their own instrument and site. MPLNET sites produce not only vertical profile data, but also column-averaged products already available from AERONET (aerosol optical depth, sky radiance, size distributions). Algorithms are presented for each MPLNET data product. Real-time Level 1 data products (next-day) include daily lidar signal images from the surface to -2Okm, and Level 1.5 aerosol extinction profiles at times co-incident with AERONET observations. Quality assured Level 2 aerosol extinction profiles are generated after screening the Level 1.5 results and removing bad data. Level 3 products include continuous day/night aerosol extinction profiles, and are produced using Level 2 calibration data. Rigorous uncertainty calculations are presented for all data products. Analysis of MPLNET data show the MPL and our analysis routines are capable of successfully retrieving aerosol profiles, with the strenuous accounting of uncertainty necessary for accurate interpretation of the results.

  15. Atmospheric extinction in solar tower plants: absorption and broadband correction for MOR measurements

    NASA Astrophysics Data System (ADS)

    Hanrieder, N.; Wilbert, S.; Pitz-Paal, R.; Emde, C.; Gasteiger, J.; Mayer, B.; Polo, J.

    2015-08-01

    measurement input of a nearby sun photometer is used to enhance on-site atmospheric assumptions for description of the atmosphere in the algorithm. Comparing both uncorrected and spectral- and absorption-corrected extinction data from 1-year measurements at the Plataforma Solar de Almería, the mean difference between the scatterometer and the transmissometer is reduced from 4.4 to 0.57 %. Applying the ABC procedure without the usage of additional input data from a sun photometer still reduces the difference between both sensors to about 0.8 %. Applying an expert guess assuming a standard aerosol profile for continental regions instead of additional sun photometer input results in a mean difference of 0.8 %. Additionally, a simulation approach which just uses sun photometer and common meteorological data to determine the on-site atmospheric extinction at surface is presented and corrected FS11 and LPV4 measurements are validated with the simulation results. For T1 km equal to 0.9 and a 10 min time resolution, an uncertainty analysis showed that an absolute uncertainty of about 0.038 is expected for the FS11 and about 0.057 for the LPV4. Combining both uncertainties results in an overall absolute uncertainty of 0.068 which justifies quite well the mean RMSE between both corrected data sets. For yearly averages several error influences average out and absolute uncertainties of 0.020 and 0.054 can be expected for the FS11 and the LPV4, respectively. Therefore, applying this new correction method, both instruments can now be utilized to sufficiently accurately determine the solar broadband extinction in tower plants.

  16. Aerosol Remote Sensing in Polar Regions

    NASA Technical Reports Server (NTRS)

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo; Ritter, Christoph; Smirnov, Alexander; O'Neill, Norman T.; Stone, Robert S.; Holben, Brent N.; Nyeki, Stephan; Wehrli, Christoph

    2014-01-01

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness tau(lambda) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent alpha were calculated. Analyzing these data, the monthly mean values of tau(0.50 micrometers) and alpha and the relative frequency histograms of the daily mean values of both parameters were determined for winter-spring and summer-autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of alpha versus tau(0.50 micrometers) showed: (i) a considerable increase in tau(0.50 micrometers) for the Arctic aerosol from summer to winter-spring, without marked changes in alpha; and (ii) a marked increase in tau(0.50 micrometer) passing from the Antarctic Plateau to coastal sites, whereas alpha decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of tau(lambda) and alpha at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterize vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of tau(lambda) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were

  17. Global volcanic aerosol properties derived from emissions, 1990-2014, using CESM1(WACCM)

    NASA Astrophysics Data System (ADS)

    Mills, Michael J.; Schmidt, Anja; Easter, Richard; Solomon, Susan; Kinnison, Douglas E.; Ghan, Steven J.; Neely, Ryan R.; Marsh, Daniel R.; Conley, Andrew; Bardeen, Charles G.; Gettelman, Andrew

    2016-03-01

    Accurate representation of global stratospheric aerosols from volcanic and nonvolcanic sulfur emissions is key to understanding the cooling effects and ozone losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global average temperature increases. We have compiled a database of volcanic SO2 emissions and plume altitudes for eruptions from 1990 to 2014 and developed a new prognostic capability for simulating stratospheric sulfate aerosols in the Community Earth System Model. We used these combined with other nonvolcanic emissions of sulfur sources to reconstruct global aerosol properties from 1990 to 2014. Our calculations show remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD) and with in situ measurements of stratospheric aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD calculations represent a clear improvement over available satellite-based analyses, which generally ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at middle and high latitudes. Our SAD calculations greatly improve on that provided for the Chemistry-Climate Model Initiative, which misses about 60% of the SAD measured in situ on average during both volcanically active and volcanically quiescent periods.

  18. Direct measurements of the optical cross sections and refractive indices of individual volatile and hygroscopic aerosol particles.

    PubMed

    Mason, B J; Cotterell, M I; Preston, T C; Orr-Ewing, A J; Reid, J P

    2015-06-04

    We present measurements of the evolving extinction cross sections of individual aerosol particles (spanning 700-2500 nm in radius) during the evaporation of volatile components or hygroscopic growth using a combination of a single particle trap formed from a Bessel light beam and cavity ring-down spectroscopy. For single component organic aerosol droplets of 1,2,6-hexanetriol, polyethylene glycol 400, and glycerol, the slow evaporation of the organic component (over time scales of 1000 to 10,000 s) leads to a time-varying size and extinction cross section that can be used to estimate the refractive index of the droplet. Measurements on binary aqueous-inorganic aerosol droplets containing one of the inorganic solutes ammonium bisulfate, ammonium sulfate, sodium nitrate, or sodium chloride (over time scales of 1000 to 15,000 s) under conditions of changing relative humidity show that extinction cross-section measurements are consistent with expectations from accepted models for the variation in droplet refractive index with hygroscopic growth. In addition, we use these systems to establish an experimental protocol for future single particle extinction measurements. The advantages of mapping out the evolving light extinction cross-section of an individual particle over extended time frames accompanied by hygroscopic cycling or component evaporation are discussed.

  19. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Maltagliati, Luca; Rodriguez, Sebastien; Sotin, Christophe; Rannou, Pascal; Bezard, Bruno; Cornet, Thomas

    2016-06-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008). Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 µm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°. We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  20. A new description of Titan's aerosol optical properties from the analysis of VIMS Emission Phase Function observations

    NASA Astrophysics Data System (ADS)

    Rodriguez, Sebastien; Maltagliati, Luca; Sotin, Christophe; Rannou, Pascal; Bézard, Bruno; Cornet, Thomas

    2016-10-01

    The Huygens probe gave unprecedented information on the properties of Titan's aerosols (vertical distribution, opacity as a function of wavelength, phase function, single scattering albedo) by in-situ measurements (Tomasko et al. 2008). Being the only existing in-situ atmospheric probing for Titan, this aerosol model currently is the reference for many Titan studies (e.g. by being applied as physical input in radiative transfer models of the atmosphere). Recently a reanalysis of the DISR dataset, corroborated by data from the Downward-Looking Visible Spectrometer (DLVS), was carried out by the same group (Doose et al. 2016), leading to significant changes to the indications given by Tomasko et al. (2008).Here we present the analysis of the Emission Phase Function observation (EPF) performed by VIMS during the Cassini flyby T88 (November 2012). An EPF observes the same spot on the surface (and thus the same atmosphere) with the same emergence angle but with different incidence angles. In this way, our EPF allows, for the first time, to have direct information on the phase function of Titan's aerosols, as well as on other important physical parameters of the aerosols as the behavior of their extinction as a function of wavelength and the single scattering albedo (also as a function of wavelength) for the whole VIMS range (0.8-5.2 μm). The T88 EPF is composed of 25 VIMS datacubes spanning a scattering angle range approximately from 0°to 70°.We used the radiative transfer model described in Hirtzig et al. (2013) as baseline, updated with improved methane (+ related isotopes) spectroscopy. By changing the aerosol description in the model, we found the combination of aerosol optical parameters that fits best a constant aerosol column density over the whole set of the VIMS datacubes. We confirmed that the new results from Doose et al. (2016) do improve the fit for what concerns the vertical profile and the extinction as a function of wavelength. However, a different

  1. Quantifying the sensitivity of aerosol optical depths retrieved from MSG SEVIRI to a priori data

    NASA Astrophysics Data System (ADS)

    Bulgin, C. E.; Palmer, P. I.; Merchant, C. J.; Siddans, R.; Poulsen, C.; Grainger, R. G.; Thomas, G.; Carboni, E.; McConnell, C.; Highwood, E.

    2009-12-01

    Radiative forcing contributions from aerosol direct and indirect effects remain one of the most uncertain components of the climate system. Satellite observations of aerosol optical properties offer important constraints on atmospheric aerosols but their sensitivity to prior assumptions must be better characterized before they are used effectively to reduce uncertainty in aerosol radiative forcing. We assess the sensitivity of the Oxford-RAL Aerosol and Cloud (ORAC) optimal estimation retrieval of aerosol optical depth (AOD) from the Spinning Enhanced Visible and InfraRed Imager (SEVIRI) to a priori aerosol data. SEVIRI is a geostationary satellite instrument centred over Africa and the neighbouring Atlantic Ocean, routinely sampling desert dust and biomass burning outflow from Africa. We quantify the uncertainty in SEVIRI AOD retrievals in the presence of desert dust by comparing retrievals that use prior information from the Optical Properties of Aerosol and Cloud (OPAC) database, with those that use measured aerosol properties during the Dust Outflow and Deposition to the Ocean (DODO) aircraft campaign (August, 2006). We also assess the sensitivity of retrieved AODs to changes in solar zenith angle, and the vertical profile of aerosol effective radius and extinction coefficient input into the retrieval forward model. Currently the ORAC retrieval scheme retrieves AODs for five aerosol types (desert dust, biomass burning, maritime, urban and continental) and chooses the most appropriate AOD based on the cost functions. We generate an improved prior aerosol speciation database for SEVIRI based on a statistical analysis of a Saharan Dust Index (SDI) determined using variances of different brightness temperatures, and organic and black carbon tracers from the GEOS-Chem chemistry transport model. This database is described as a function of season and time of day. We quantify the difference in AODs between those chosen based on prior information from the SDI and GEOS

  2. Profile of heating rate due to aerosols using lidar and skyradiometer in SKYNET Hefei site

    NASA Astrophysics Data System (ADS)

    Wang, Z.; Liu, D.; Xie, C.

    2015-12-01

    Atmospheric aerosols have a significant impact on climate due to their important role in modifying atmosphere energy budget. On global scale, the direct radiative forcing is estimated to be in the range of -0.9 to -0.1 Wm-2 for aerosols [1]. Yet, these estimates are subject to very large uncertainties because of uncertainties in spatial and temporal variations of aerosols. At local scales, as aerosol properties can vary spatially and temporally, radiative forcing due to aerosols can be also very different and it can exceed the global value by an order of magnitude. Hence, it is very important to investigate aerosol loading, properties, and radiative forcing due to them in detail on local regions of climate significance. Haze and dust events in Hefei, China are explored by Lidar and Skyradiometer. Aerosol optical properties including the AOD, SSA, AAE and size distribution are analysed by using the SKYRAD.PACK [2] and presented in this paper. Furthermore, the radiative forcing due to aerosols and the heating rate in the ATM are also calculated using SBDART model [3]. The results are shown that the vertical heating rate is tightly related to aerosol profile. References: 1. IPCC. 2007. Climate Change 2007: The Physical Science Basic. Contribution of Working Group I Contribution to the Intergovernmental Panel on Climate Change Fourth Assessment Report. Solomon S, Qing D H, Manning M, et al. eds., Cambridge University Press, Cambridge, United Kingdom and New York, N Y, USA. 2. Nakajima, T., G. Tonna, R. Rao, Y. Kaufman, and B. Holben, 1996: Use of sky brightness measurements from ground for remote sensing of particulate poly dispersions, Appl. Opt., 35, 2672-2686. 3. Ricchiazzi et al 1998. SBDART: a research and teaching software tool for plane-parallel radiative transfer in the Earth's atmosphere,Bulletin of the American Meteorological Society,79,2101-2114.

  3. Top-down and bottom-up aerosol-cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

    NASA Astrophysics Data System (ADS)

    Sanchez, Kevin J.; Roberts, Gregory C.; Calmer, Radiance; Nicoll, Keri; Hashimshoni, Eyal; Rosenfeld, Daniel; Ovadnevaite, Jurgita; Preissler, Jana; Ceburnis, Darius; O'Dowd, Colin; Russell, Lynn M.

    2017-08-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60 W m-2. After accounting for entrainment

  4. Laboratory Experiments and Instrument Intercomparison Studies of Carbonaceous Aerosol Particles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Davidovits, Paul

    Aerosols containing black carbon (and some specific types of organic particulate matter) directly absorb incoming light, heating the atmosphere. In addition, all aerosol particles backscatter solar light, leading to a net-cooling effect. Indirect effects involve hydrophilic aerosols, which serve as cloud condensation nuclei (CCN) that affect cloud cover and cloud stability, impacting both atmospheric radiation balance and precipitation patterns. At night, all clouds produce local warming, but overall clouds exert a net-cooling effect on the Earth. The effect of aerosol radiative forcing on climate may be as large as that of the greenhouse gases, but predominantly opposite in sign andmore » much more uncertain. The uncertainties in the representation of aerosol interactions in climate models makes it problematic to use model projections to guide energy policy. The objective of our program is to reduce the uncertainties in the aerosol radiative forcing in the two areas highlighted in the ASR Science and Program Plan. That is, (1) addressing the direct effect by correlating particle chemistry and morphology with particle optical properties (i.e. absorption, scattering, extinction), and (2) addressing the indirect effect by correlating particle hygroscopicity and CCN activity with particle size, chemistry, and morphology. In this connection we are systematically studying particle formation, oxidation, and the effects of particle coating. The work is specifically focused on carbonaceous particles where the uncertainties in the climate relevant properties are the highest. The ongoing work consists of laboratory experiments and related instrument inter-comparison studies both coordinated with field and modeling studies, with the aim of providing reliable data to represent aerosol processes in climate models. The work is performed in the aerosol laboratory at Boston College. At the center of our laboratory setup are two main sources for the production of aerosol

  5. Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the UK

    NASA Astrophysics Data System (ADS)

    McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.

    2011-05-01

    Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the UK. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA observed in

  6. Airborne Sunphotometer Measurements of Aerosol Optical Depth and Columnar Water Vapor During the Puerto Rico Dust Experiment, and Comparison with Land, Aircraft, and Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Russell, Philip B.; Reid, Jeffrey; Redemann, Jens; Schmid, Beat; Allen, Duane A.; Torres, Omar; Levy, Robert C.; Remer, Lorraine A.; Holben, Brent N.; hide

    2002-01-01

    Analyses of aerosol optical depth (AOD) and columnar water vapor (CWV) measurements obtained with the six-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) mounted on a twin-engine aircraft during the summer 2000 Puerto Rico Dust Experiment are presented. In general, aerosol extinction values calculated from AATS-6 AOD measurements acquired during aircraft profiles up to 5 km ASL reproduce the vertical structure measured by coincident aircraft in-situ measurements of total aerosol number and surface area concentration. Calculations show that the spectral dependence of AOD was small (mean Angstrom wavelength exponents of approximately 0.20) within three atmospheric layers defined as the total column beneath the top of each aircraft profile, the region beneath the trade wind inversion, and the region within the Saharan Air Layer (SAL) above the trade inversion. This spectral behavior is consistent with attenuation of incoming solar radiation by large dust particles or by dust plus sea salt. Values of CWV calculated from profile measurements by AATS-6 at 941.9 nm and from aircraft in-situ measurements by a chilled mirror dewpoint hygrometer agree to within approximately 4% (0.13 g/sq cm). AATS-6 AOD values measured on the ground at Roosevelt Roads Naval Air Station and during low altitude aircraft runs over the adjacent Cabras Island aerosol/radiation ground site agree to within 0.004 to 0.030 with coincident data obtained with an AERONET Sun/sky Cimel radiometer located at Cabras Island. For the same observation times, AERONET retrievals of CWV exceed AATS-6 values by a mean of 0.74 g/sq cm (approximately 21 %) for the 2.9-3.9 g/sq cm measured by AATS-6. Comparison of AATS-6 aerosol extinction values obtained during four aircraft ascents over Cabras Island with corresponding values calculated from coincident aerosol backscatter measurements by a ground-based micro-pulse lidar (MPL-Net) located at Cabras yields a similar vertical structure above the trade

  7. Relationship Between Aerosol Optical Depth and Particulate Matter Over Singapore: Effects of Aerosol Vertical Distributions

    NASA Technical Reports Server (NTRS)

    Chew, Boo Ning; Campbell, James; Hyer, Edward J.; Salinas, Santo V.; Reid, Jeffrey S.; Welton, Ellsworth J.; Holben, Brent N.; Liew, Soo Chin

    2016-01-01

    As part of the Seven Southeast Asian Studies (7SEAS) program, an Aerosol Robotic Network (AERONET) sun photometer and a Micro-Pulse Lidar Network (MPLNET) instrument have been deployed at Singapore to study the regional aerosol environment of the Maritime Continent (MC). In addition, the Navy Aerosol Analysis and Prediction System (NAAPS) is used to model aerosol transport over the region. From 24 September 2009 to 31 March 2011, the relationships between ground-, satellite- and model-based aerosol optical depth (AOD) and particulate matter with aerodynamic equivalent diameters less than 2.5 microns (PM2.5) for air quality applications are investigated. When MPLNET-derived aerosol scale heights are applied to normalize AOD for comparison with surface PM2.5 data, the empirical relationships are shown to improve with an increased 11%, 10% and 5% in explained variances, for AERONET, MODIS and NAAPS respectively. The ratios of root mean square errors to standard deviations for the relationships also show corresponding improvements of 8%, 6% and 2%. Aerosol scale heights are observed to be bimodal with a mode below and another above the strongly-capped/deep near-surface layer (SCD; 0-1.35 km). Aerosol extinctions within the SCD layer are well-correlated with surface PM2.5 concentrations, possibly due to strong vertical mixing in the region.

  8. Global optical climatology of the free tropospheric aerosol from 1.0-micron satellite occultation measurements

    NASA Technical Reports Server (NTRS)

    Kent, G. S.; Schaffner, S. K.; Mccormick, M. P.

    1991-01-01

    Measurements of the aerosol/molecular extinction ratio at 1-micron wavelength, obtained from the SAGE I, SAGE II, and SAM II solar occultation satellite experiments between 1978 and 1986, have been used to study the global-scale behavior of the upper tropospheric aerosol. The distribution of extinction ratio values shows a pronounced mode between about 0.5 and 5 in all data subsets, regardless of latitude and season. Within a given latitude band and season with mode value is nearly constant over the altitude range from about 5 km above the earth's surface to 3 km below the tropopause. The mode shows a distinct seasonal variation, with maxima in local spring and summer, and is significantly enhanced following vlocanic injection of material into the stratosphere. South of latitude 20-deg N, mode values in the absence of volcanic contamination are normally between 0.5 and 1.0 north of 20-deg N, values up to about 5 are observed, probably associated with aerosol derived from surface dust or anthropogenic sources. A secondary mode, with extinction ratios of 30 or greater and little or no variation of extinction with wavelength, is apparent just below the tropopause. This mode is believed to be associated with thin cloud along the ray path from the sun to the satellite.

  9. Vertically-resolved profiles of mass concentrations and particle backscatter coefficients of Asian dust plumes derived from lidar observations of silicon dioxide.

    PubMed

    Noh, Youngmin; Müller, Detlef; Shin, Sung-Kyun; Shin, Dongho; Kim, Young J

    2016-01-01

    This study presents a method to retrieve vertically-resolved profiles of dust mass concentrations by analyzing Raman lidar signals of silicon dioxide (quartz) at 546nm. The observed particle plumes consisted of mixtures of East Asian dust with anthropogenic pollution. Our method for the first time allows for extracting the contribution of the aerosol component "pure dust" contained in the aerosol type "polluted dust". We also propose a method that uses OPAC (Optical Properties of Aerosols and Clouds) and the mass concentrations profiles of dust in order to derive profiles of backscatter coefficients of pure dust in mixed dust/pollution plumes. The mass concentration of silicon dioxide (quartz) in the atmosphere can be estimated from the backscatter coefficient of quartz. The mass concentration of dust is estimated by the weight percentage (38-77%) of mineral quartz in Asian dust. The retrieved dust mass concentrations are classified into water soluble, nucleation, accumulation, mineral-transported and coarse mode according to OPAC. The mass mixing ratio of 0.018, 0.033, 0.747, 0.130 and 0.072, respectively, is used. Dust extinction coefficients at 550nm were calculated by using OPAC and prescribed number concentrations for each of the 5 components. Dust backscatter coefficients were calculated from the dust extinction coefficients on the basis of a lidar ratio of 45±3sr at 532nm. We present results of quartz-Raman measurements carried out on the campus of the Gwangju Institute of Science and Technology (35.10°N, 126.53°E) on 15, 16, and 21 March 2010. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Approach to simultaneously denoise and invert backscatter and extinction from photon-limited atmospheric lidar observations.

    PubMed

    Marais, Willem J; Holz, Robert E; Hu, Yu Hen; Kuehn, Ralph E; Eloranta, Edwin E; Willett, Rebecca M

    2016-10-10

    Atmospheric lidar observations provide a unique capability to directly observe the vertical column of cloud and aerosol scattering properties. Detector and solar-background noise, however, hinder the ability of lidar systems to provide reliable backscatter and extinction cross-section estimates. Standard methods for solving this inverse problem are most effective with high signal-to-noise ratio observations that are only available at low resolution in uniform scenes. This paper describes a novel method for solving the inverse problem with high-resolution, lower signal-to-noise ratio observations that are effective in non-uniform scenes. The novelty is twofold. First, the inferences of the backscatter and extinction are applied to images, whereas current lidar algorithms only use the information content of single profiles. Hence, the latent spatial and temporal information in noisy images are utilized to infer the cross-sections. Second, the noise associated with photon-counting lidar observations can be modeled using a Poisson distribution, and state-of-the-art tools for solving Poisson inverse problems are adapted to the atmospheric lidar problem. It is demonstrated through photon-counting high spectral resolution lidar (HSRL) simulations that the proposed algorithm yields inverted backscatter and extinction cross-sections (per unit volume) with smaller mean squared error values at higher spatial and temporal resolutions, compared to the standard approach. Two case studies of real experimental data are also provided where the proposed algorithm is applied on HSRL observations and the inverted backscatter and extinction cross-sections are compared against the standard approach.

  11. Quantitative retrieval of aerosol optical properties by means of ceilometers

    NASA Astrophysics Data System (ADS)

    Wiegner, Matthias; Gasteiger, Josef; Geiß, Alexander

    2016-04-01

    In the last few years extended networks of ceilometers have been established by several national weather services. Based on improvements of the hardware performance of these single-wavelength backscatter lidars and their 24/7 availability they are increasingly used to monitor mixing layer heights and to derive profiles of the particle backscatter profile. As a consequence they are used for a wide range of applications including the dispersion of volcanic ash plumes, validation of chemistry transport models and air quality studies. In this context the development of automated schemes to detect aerosol layers and to identify the mixing layer are essential, in particular as the latter is often used as a proxy for air quality. Of equal importance is the calibration of ceilometer signals as a pre-requisite to derive quantitative optical properties. Recently, it has been emphasized that the majority of ceilometers are influenced by water vapor absorption as they operate in the spectral range of 905 - 910 nm. If this effect is ignored, errors of the aerosol backscatter coefficient can be as large as 50%, depending on the atmospheric water vapor content and the emitted wavelength spectrum. As a consequence, any other derived quantity, e.g. the extinction coefficient or mass concentration, would suffer from a significant uncertainty in addition to the inherent errors of the inversion of the lidar equation itself. This can be crucial when ceilometer derived profiles shall be used to validate transport models. In this presentation, the methodology proposed by Wiegner and Gasteiger (2015) to correct for water vapor absorption is introduced and discussed.

  12. Assessing the measurement of aerosol single scattering albedo by Cavity Attenuated Phase-Shift Single Scattering Monitor (CAPS PMssa)

    NASA Astrophysics Data System (ADS)

    Perim de Faria, Julia; Bundke, Ulrich; Onasch, Timothy B.; Freedman, Andrew; Petzold, Andreas

    2016-04-01

    The necessity to quantify the direct impact of aerosol particles on climate forcing is already well known; assessing this impact requires continuous and systematic measurements of the aerosol optical properties. Two of the main parameters that need to be accurately measured are the aerosol optical depth and single scattering albedo (SSA, defined as the ratio of particulate scattering to extinction). The measurement of single scattering albedo commonly involves the measurement of two optical parameters, the scattering and the absorption coefficients. Although there are well established technologies to measure both of these parameters, the use of two separate instruments with different principles and uncertainties represents potential sources of significant errors and biases. Based on the recently developed cavity attenuated phase shift particle extinction monitor (CAPS PM_{ex) instrument, the CAPS PM_{ssa instrument combines the CAPS technology to measure particle extinction with an integrating sphere capable of simultaneously measuring the scattering coefficient of the same sample. The scattering channel is calibrated to the extinction channel, such that the accuracy of the single scattering albedo measurement is only a function of the accuracy of the extinction measurement and the nephelometer truncation losses. This gives the instrument an accurate and direct measurement of the single scattering albedo. In this study, we assess the measurements of both the extinction and scattering channels of the CAPS PM_{ssa through intercomparisons with Mie theory, as a fundamental comparison, and with proven technologies, such as integrating nephelometers and filter-based absorption monitors. For comparison, we use two nephelometers, a TSI 3563 and an Aurora 4000, and two measurements of the absorption coefficient, using a Particulate Soot Absorption Photometer (PSAP) and a Multi Angle Absorption Photometer (MAAP). We also assess the indirect absorption coefficient

  13. Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

    NASA Astrophysics Data System (ADS)

    Mamali, Dimitra; Marinou, Eleni; Sciare, Jean; Pikridas, Michael; Kokkalis, Panagiotis; Kottas, Michael; Binietoglou, Ioannis; Tsekeri, Alexandra; Keleshis, Christos; Engelmann, Ronny; Baars, Holger; Ansmann, Albert; Amiridis, Vassilis; Russchenberg, Herman; Biskos, George

    2018-05-01

    In situ measurements using unmanned aerial vehicles (UAVs) and remote sensing observations can independently provide dense vertically resolved measurements of atmospheric aerosols, information which is strongly required in climate models. In both cases, inverting the recorded signals to useful information requires assumptions and constraints, and this can make the comparison of the results difficult. Here we compare, for the first time, vertical profiles of the aerosol mass concentration derived from light detection and ranging (lidar) observations and in situ measurements using an optical particle counter on board a UAV during moderate and weak Saharan dust episodes. Agreement between the two measurement methods was within experimental uncertainty for the coarse mode (i.e. particles having radii > 0.5 µm), where the properties of dust particles can be assumed with good accuracy. This result proves that the two techniques can be used interchangeably for determining the vertical profiles of aerosol concentrations, bringing them a step closer towards their systematic exploitation in climate models.

  14. Infrared Aerosol Radiative Forcing at the Surface and the Top of the Atmosphere

    NASA Technical Reports Server (NTRS)

    Markowicz, Krzysztof M.; Flatau, Piotr J.; Vogelmann, Andrew M.; Quinn, Patricia K.; Welton, Ellsworth J.

    2003-01-01

    We study the clear-sky aerosol radiative forcing at infrared wavelengths using data from the Aerosol Characterization Experiment (ACE-Asia) cruise of the NOAA R/V Ronald H. Brown. Limited number of data points is analyzed mostly from ship and collocated satellite values. An optical model is derived from chemical measurements, lidar profiles, and visible extinction measurements which is used to and estimate the infrared aerosol optical thickness and the single scattering albedo. The IR model results are compared to detailed Fourier Transform Interferometer based infrared aerosol forcing estimates, pyrgeometer based infrared downward fluxes, and against the direct solar forcing observations. This combined approach attests for the self-consistency of the optical model and allows to derive quantities such as the infrared forcing at the top of the atmosphere or the infrared optical thickness. The mean infrared aerosol optical thickness at 10 microns is 0.08 and the single scattering albedo is 0.55. The modeled infrared aerosol forcing reaches 10 W/sq m during the cruise, which is a significant contribution to the total direct aerosol forcing. The surface infrared aerosol radiative forcing is between 10 to 25% of the shortwave aerosol forcing. The infrared aerosol forcing at the top of the atmosphere can go up to 19% of the solar aerosol forcing. We show good agreement between satellite (CERES instrument) retrievals and model results at the top of the atmosphere. Over the Sea of Japan, the average infrared radiative forcing is 4.6 W/sq m in the window region at the surface and it is 1.5 W/sq m at top of the atmosphere. The top of the atmosphere IR forcing efficiency is a strong function of aerosol temperature while the surface IR forcing efficiency varies between 37 and 55 W/sq m (per infrared optical depth unit). and changes between 10 to 18 W/sq m (per infrared optical depth unit).

  15. SIZE DISTRIBUTIONS OF ELEMENTAL CARBON IN ATMOSPHERIC AEROSOLS

    EPA Science Inventory

    Environmental problems caused by atmospheric aerosols are well documented in the specialized literature. Studies reporting on the role of dense clouds of soil particles in past mass extinctions of life on Earth and, more recently (Turco et al., 1983), on calculations of potential...

  16. Study of atmospheric aerosols over the central Himalayan region using a newly developed Mie light detection and ranging system: preliminary results

    NASA Astrophysics Data System (ADS)

    Bangia, Tarun; Omar, Amitesh; Sagar, Ram; Kumar, Ashish; Bhattacharjee, Samaresh; Reddy, Arjun; Agarwal, Prem Kumar; Phanikumar

    2011-01-01

    A LIDAR system to receive Mie backscattered photons has been developed at the Manora peak, Nainital, India and it is the first of its kind in the central Himalayan region. The system is sensitive to receive backscattered photons from heights up to ~20 km (above ground level). The atmospheric extinction profiles using Mie LIDAR have been estimated for the first time at this site in January (winter) and March (spring) seasons in three campaigns and maximum values are found to be ~0.01, 0.03, and 0.08 km-1, respectively. The aerosol optical depth (AOD) values are found to be ~0.051, 0.098, and 0.233 in three campaigns, respectively, showing enhancement from January (winter) to March (spring) indicating a seasonal variation. AOD values of LIDAR, aerosol robotic network, and moderate resolution imaging spectroradiometer were found within the standard deviations. The aerosol loading at the site has increased during the last decade as evident from previous studies.

  17. Identifying Aerosol Type/Mixture from Aerosol Absorption Properties Using AERONET

    NASA Technical Reports Server (NTRS)

    Giles, D. M.; Holben, B. N.; Eck, T. F.; Sinyuk, A.; Dickerson, R. R.; Thompson, A. M.; Slutsker, I.; Li, Z.; Tripathi, S. N.; Singh, R. P.; hide

    2010-01-01

    Aerosols are generated in the atmosphere through anthropogenic and natural mechanisms. These sources have signatures in the aerosol optical and microphysical properties that can be used to identify the aerosol type/mixture. Spectral aerosol absorption information (absorption Angstrom exponent; AAE) used in conjunction with the particle size parameterization (extinction Angstrom exponent; EAE) can only identify the dominant absorbing aerosol type in the sample volume (e.g., black carbon vs. iron oxides in dust). This AAE/EAE relationship can be expanded to also identify non-absorbing aerosol types/mixtures by applying an absorption weighting. This new relationship provides improved aerosol type distinction when the magnitude of absorption is not equal (e.g, black carbon vs. sulfates). The Aerosol Robotic Network (AERONET) data provide spectral aerosol optical depth and single scattering albedo - key parameters used to determine EAE and AAE. The proposed aerosol type/mixture relationship is demonstrated using the long-term data archive acquired at AERONET sites within various source regions. The preliminary analysis has found that dust, sulfate, organic carbon, and black carbon aerosol types/mixtures can be determined from this AAE/EAE relationship when applying the absorption weighting for each available wavelength (Le., 440, 675, 870nm). Large, non-spherical dust particles absorb in the shorter wavelengths and the application of 440nm wavelength absorption weighting produced the best particle type definition. Sulfate particles scatter light efficiently and organic carbon particles are small near the source and aggregate over time to form larger less absorbing particles. Both sulfates and organic carbon showed generally better definition using the 870nm wavelength absorption weighting. Black carbon generation results from varying combustion rates from a number of sources including industrial processes and biomass burning. Cases with primarily black carbon showed

  18. Autonomous microfluidic sample preparation system for protein profile-based detection of aerosolized bacterial cells and spores.

    PubMed

    Stachowiak, Jeanne C; Shugard, Erin E; Mosier, Bruce P; Renzi, Ronald F; Caton, Pamela F; Ferko, Scott M; Van de Vreugde, James L; Yee, Daniel D; Haroldsen, Brent L; VanderNoot, Victoria A

    2007-08-01

    For domestic and military security, an autonomous system capable of continuously monitoring for airborne biothreat agents is necessary. At present, no system meets the requirements for size, speed, sensitivity, and selectivity to warn against and lead to the prevention of infection in field settings. We present a fully automated system for the detection of aerosolized bacterial biothreat agents such as Bacillus subtilis (surrogate for Bacillus anthracis) based on protein profiling by chip gel electrophoresis coupled with a microfluidic sample preparation system. Protein profiling has previously been demonstrated to differentiate between bacterial organisms. With the goal of reducing response time, multiple microfluidic component modules, including aerosol collection via a commercially available collector, concentration, thermochemical lysis, size exclusion chromatography, fluorescent labeling, and chip gel electrophoresis were integrated together to create an autonomous collection/sample preparation/analysis system. The cycle time for sample preparation was approximately 5 min, while total cycle time, including chip gel electrophoresis, was approximately 10 min. Sensitivity of the coupled system for the detection of B. subtilis spores was 16 agent-containing particles per liter of air, based on samples that were prepared to simulate those collected by wetted cyclone aerosol collector of approximately 80% efficiency operating for 7 min.

  19. Retrievals of aerosol microphysics from simulations of spaceborne multiwavelength lidar measurements

    NASA Astrophysics Data System (ADS)

    Whiteman, David N.; Pérez-Ramírez, Daniel; Veselovskii, Igor; Colarco, Peter; Buchard, Virginie

    2018-01-01

    In support of the Aerosol, Clouds, Ecosystems mission, simulations of a spaceborne multiwavelength lidar are performed based on global model simulations of the atmosphere along a satellite orbit track. The yield for aerosol microphysical inversions is quantified and comparisons are made between the aerosol microphysics inherent in the global model and those inverted from both the model's optical data and the simulated three backscatter and two extinction lidar measurements, which are based on the model's optical data. We find that yield can be significantly increased if inversions based on a reduced optical dataset of three backscatter and one extinction are acceptable. In general, retrieval performance is better for cases where the aerosol fine mode dominates although a lack of sensitivity to particles with sizes less than 0.1 μm is found. Lack of sensitivity to coarse mode cases is also found, in agreement with earlier studies. Surface area is generally the most robustly retrieved quantity. The work here points toward the need for ancillary data to aid in the constraints of the lidar inversions and also for joint inversions involving lidar and polarimeter measurements.

  20. Retrievals of Aerosol Microphysics from Simulations of Spaceborne Multiwavelength Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.; Perez-Ramírez, Daniel; Veselovskii, Igor; Colarco, Peter; Buchard, Virginie

    2017-01-01

    In support of the Aerosol, Clouds, Ecosystems mission, simulations of a spaceborne multiwavelength lidar are performed based on global model simulations of the atmosphere along a satellite orbit track. The yield for aerosol microphysical inversions is quantified and comparisons are made between the aerosol microphysics inherent in the global model and those inverted from both the model's optical data and the simulated three backscatter and two extinction lidar measurements, which are based on the model's optical data. We find that yield can be significantly increased if inversions based on a reduced optical dataset of three backscatter and one extinction are acceptable. In general, retrieval performance is better for cases where the aerosol fine mode dominates although a lack of sensitivity to particles with sizes less than 0.1 microns is found. Lack of sensitivity to coarse mode cases is also found, in agreement with earlier studies. Surface area is generally the most robustly retrieved quantity. The work here points toward the need for ancillary data to aid in the constraints of the lidar inversions and also for joint inversions involving lidar and polarimeter measurements.

  1. Springtime major pollution events by aerosol over Paris Area: From a case study to a multiannual analysis

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Royer, Philippe

    2017-08-01

    A study of the intense spring pollution events occurring between 2007 and 2016 on the Paris Area is presented using ground-based and spaceborne measurements. Emphasis is placed on 2011 where data included ground-based lidar measurements. This last period corresponds with the highest regional pollution levels of the past decade. The information threshold (daily average of (mass concentration of particles with aerodynamic diameter less than 10 μm) PM10 > 50 μg m-3) was exceeded 16 times, while the alert threshold (daily average of PM10 > 80 μg m-3) was exceeded twice. The information (alert) threshold exists to protect the most fragile people (the entire population). Ground-based and spaceborne measurements demonstrate the benefit of their synergy as each is representative of specific space and time scales. The operational products of the spaceborne instruments Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and the Moderate Resolution Imaging Spectroradiometer are used. For 2011, CALIOP vertical profiles are inversed to assess the backscatter to extinction ratio, which is then successfully compared with similar results derived from the CALIOP operational products, a ground-based lidar and Sun photometers. The aerosols are identified to be polluted continental and polluted dust aerosols following the criteria used for the inversion of the CALIOP profiles. Aerosol typing is consistent between the ground-based and spaceborne lidars, demonstrating the importance of CALIOP for other years where the ground-based lidar was not in operation. The main pollution sources responsible for the spring aerosol pollution, occurring during anticyclonic meteorological conditions, are identified as coming from Western Europe: Benelux, Rhine-Ruhr area, and the Lorraine area.

  2. New Measurements of Aerosol Vertical Structure from Space Using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Ginoux, Paul; Colarco, Peter; Chin, Mian; Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis; Hart, William

    2003-01-01

    In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GUS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output,

  3. New Measurements of Aerosol Vertical Structure from Space using the NASA Geoscience Laser Altimeter System (GLAS): Applications for Aerosol Transport Models

    NASA Technical Reports Server (NTRS)

    Welton, E. J.; Spinhime, J.; Palm, S.; Hlavka, D.; Hart, W.; Ginoux, P.; Chin, M.; Colarco, P.

    2004-01-01

    In the past, satellite measurements of aerosols have only been possible using passive sensors. Analysis of passive satellite data has lead to an improved understanding of aerosol properties, spatial distribution, and their effect on the earth,s climate. However, direct measurement of aerosol vertical distribution has not been possible using only the passive data. Knowledge of aerosol vertical distribution is important to correctly assess the impact of aerosol absorption, for certain atmospheric correction procedures, and to help constrain height profiles in aerosol transport models. On January 12,2003 NASA launched the first satellite-based lidar, the Geoscience Laser Altimeter System (GLAS), onboard the ICESat spacecraft. GLAS is both an altimeter and an atmospheric lidar, and obtains direct measurements of aerosol and cloud heights. Here we show an overview of GLAS, provide an update of its current status, and discuss how GLAS data will be useful for modeling efforts. In particular, a strategy of using GLAS to characterize the height profile of dust plumes over source regions will be presented, along with initial results. Such information can be used to validate and improve output from aerosol transport models. Aerosol height profile comparisons between GLAS and transport models will be shown for regions downwind of aerosol sources. We will also discuss the feasibility of assimilating GLAS profiles into the models in order to improve their output.

  4. Black carbon aerosol mixing state, organic aerosols and aerosol optical properties over the United Kingdom

    NASA Astrophysics Data System (ADS)

    McMeeking, G. R.; Morgan, W. T.; Flynn, M.; Highwood, E. J.; Turnbull, K.; Haywood, J.; Coe, H.

    2011-09-01

    Black carbon (BC) aerosols absorb sunlight thereby leading to a positive radiative forcing and a warming of climate and can also impact human health through their impact on the respiratory system. The state of mixing of BC with other aerosol species, particularly the degree of internal/external mixing, has been highlighted as a major uncertainty in assessing its radiative forcing and hence its climate impact, but few in situ observations of mixing state exist. We present airborne single particle soot photometer (SP2) measurements of refractory BC (rBC) mass concentrations and mixing state coupled with aerosol composition and optical properties measured in urban plumes and regional pollution over the United Kingdom. All data were obtained using instrumentation flown on the UK's BAe-146-301 large Atmospheric Research Aircraft (ARA) operated by the Facility for Airborne Atmospheric Measurements (FAAM). We measured sub-micron aerosol composition using an aerosol mass spectrometer (AMS) and used positive matrix factorization to separate hydrocarbon-like (HOA) and oxygenated organic aerosols (OOA). We found a higher number fraction of thickly coated rBC particles in air masses with large OOA relative to HOA, higher ozone-to-nitrogen oxides (NOx) ratios and large concentrations of total sub-micron aerosol mass relative to rBC mass concentrations. The more ozone- and OOA-rich air masses were associated with transport from continental Europe, while plumes from UK cities had higher HOA and NOx and fewer thickly coated rBC particles. We did not observe any significant change in the rBC mass absorption efficiency calculated from rBC mass and light absorption coefficients measured by a particle soot absorption photometer despite observing significant changes in aerosol composition and rBC mixing state. The contributions of light scattering and absorption to total extinction (quantified by the single scattering albedo; SSA) did change for different air masses, with lower SSA

  5. Enabling Characteristics Of Optical Autocovariance Lidar For Global Wind And Aerosol Profiling

    NASA Astrophysics Data System (ADS)

    Grund, C. J.; Stephens, M.; Lieber, M.; Weimer, C.

    2008-12-01

    Systematic global wind measurements with 70 km horizontal resolution and, depending on altitude from the PBL to stratosphere, 250m-2km vertical resolution and 0.5m/s - 2 m/s velocity precision are recognized as key to the understanding and monitoring of complex climate modulations, validation of models, and improved precision and range for weather forecasts. Optical Autocovariance Wind Lidar (OAWL) is a relatively new interferometric direct detection Doppler lidar approach that promises to meet the required wind profile resolution at substantial mass, cost, and power savings, and at reduced technical risk for a space-based system meeting the most demanding velocity precision and spatial and temporal resolution requirements. A proof of concept Optical Autocovariance Wind Lidar (OAWL) has been demonstrated, and a robust multi- wavelength, field-widened (more than 100 microR) lidar system suitable for high altitude (over 16km) aircraft demonstration is under construction. Other advantages of the OAWL technique include insensitivity to aerosol/molecular backscatter mixing ratio, freedom from complex receiver/transmitter optical frequency lock loops, prospects for practical continuous large-area coverage wind profiling from GEO, and the availability of simultaneous multiple wavelength High Spectral Resolution Lidar (OA-HSRL) for aerosol identification and optical property measurements. We will discuss theory, development and demonstration status, advantages, limitations, and space-based performance of OAWL and OA-HSRL, as well as the potential for combined mission synergies.

  6. Separating Dust Mixtures and Other External Aerosol Mixtures Using Airborne High Spectral Resolution Lidar Data

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Vaughan, M.; Hostetler, C. A.; Rogers, R. R.; Hair, J. W.; Cook, A. L.; Harper, D. B.

    2013-12-01

    Knowledge of aerosol type is important for source attribution and for determining the magnitude and assessing the consequences of aerosol radiative forcing. The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL-1) has acquired considerable datasets of both aerosol extensive parameters (e.g. aerosol optical depth) and intensive parameters (e.g. aerosol depolarization ratio, lidar ratio) that can be used to infer aerosol type. An aerosol classification methodology has been used extensively to classify HSRL-1 aerosol measurements of different aerosol types including dust, smoke, urban pollution, and marine aerosol. However, atmospheric aerosol is frequently not a single pure type, but instead occurs as a mixture of types, and this mixing affects the optical and radiative properties of the aerosol. Here we present a comprehensive and unified set of rules for characterizing external mixtures using several key aerosol intensive parameters: extinction-to-backscatter ratio (i.e. lidar ratio), backscatter color ratio, and depolarization ratio. Our mixing rules apply not just to the scalar values of aerosol intensive parameters, but to multi-dimensional normal distributions with variance in each measurement dimension. We illustrate the applicability of the mixing rules using examples of HSRL-1 data where mixing occurred between different aerosol types, including advected Saharan dust mixed with the marine boundary layer in the Caribbean Sea and locally generated dust mixed with urban pollution in the Mexico City surroundings. For each of these cases we infer a time-height cross section of mixing ratio along the flight track and we partition aerosol extinction into portions attributed to the two pure types. Since multiple aerosol intensive parameters are measured and included in these calculations, the techniques can also be used for cases without significant depolarization (unlike similar work by earlier researchers), and so a third example of a

  7. Extinction-to-Backscatter Ratios of Saharan Dust Layers Derived from In-Situ Measurements and CALIPSO Overflights During NAMMA

    NASA Technical Reports Server (NTRS)

    Omar, Ali H.; Liu, Zhaoyan; Vaughan, Mark A.; Thornhill, Kenneth L., II; Kittaka, Chieko; Ismail, Syed; Chen, Gao; Powell, Kathleen A.; Winker, David M.; Trepte, Charles R.; hide

    2010-01-01

    We determine the extinction-to-backscatter (Sa) ratios of dust using (1) airborne in-situ measurements of microphysical properties, (2) modeling studies, and (3) the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) observations recorded during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment conducted from Sal, Cape Verde during Aug-Sept 2006. Using CALIPSO measurements of the attenuated backscatter of lofted Saharan dust layers, we apply the transmittance technique to estimate dust Sa ratios at 532 nm and a 2-color method to determine the corresponding 1064 nm Sa. This method yielded dust Sa ratios of 39.8 plus or minus 1.4 sr and 51.8 plus or minus 3.6 sr at 532 nm and 1064 nm, respectively. Secondly, Sa at both wavelengths is independently calculated using size distributions measured aboard the NASA DC-8 and estimates of Saharan dust complex refractive indices applied in a T-Matrix scheme. We found Sa ratios of 39.1 plus or minus 3.5 sr and 50.0 plus or minus 4 sr at 532 nm and 1064 nm, respectively, using the T-Matrix calculations applied to measured size spectra. Finally, in situ measurements of the total scattering (550 nm) and absorption coefficients (532 nm) are used to generate an extinction profile that is used to constrain the CALIPSO 532 nm extinction profile and thus generate a stratified 532 nm Sa. This method yielded an Sa ratio at 532 nm of 35.7 sr in the dust layer and 25 sr in the marine boundary layer consistent with a predominantly seasalt aerosol near the ocean surface. Combinatorial simulations using noisy size spectra and refractive indices were used to estimate the mean and uncertainty (one standard deviation) of these Sa ratios. These simulations produced a mean (plus or minus uncertainty) of 39.4 (plus or minus 5.9) sr and 56.5 (plus or minus 16.5) sr at 532 nm and 1064 nm, respectively, corresponding to percent uncertainties of 15% and 29%. These results will provide a measurements

  8. Composition and physical properties of the Asian Tropopause Aerosol Layer and the North American Tropospheric Aerosol Layer: Composition of ATAL and NATAL

    DOE PAGES

    Yu, Pengfei; Toon, Owen B.; Neely, Ryan R.; ...

    2015-04-10

    Recent studies revealed layers of enhanced aerosol scattering in the upper troposphere and lower stratosphere over Asia (Asian Tropopause Aerosol Layer (ATAL)) and North America (North American Tropospheric Aerosol Layer (NATAL)). We use a sectional aerosol model (Community Aerosol and Radiation Model for Atmospheres (CARMA)) coupled with the Community Earth System Model version 1 (CESM1) to explore the composition and optical properties of these aerosol layers. The observed aerosol extinction enhancement is reproduced by CESM1/CARMA. Both model and observations indicate a strong gradient of the sulfur-to-carbon ratio from Europe to the Asia on constant pressure surfaces. We found that themore » ATAL is mostly composed of sulfates, surface-emitted organics, and secondary organics; the NATAL is mostly composed of sulfates and secondary organics. In conclusion, the model also suggests that emission increases in Asia between 2000 and 2010 led to an increase of aerosol optical depth of the ATAL by 0.002 on average which is consistent with observations.« less

  9. Composition and physical properties of the Asian Tropopause Aerosol Layer and the North American Tropospheric Aerosol Layer: Composition of ATAL and NATAL

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yu, Pengfei; Toon, Owen B.; Neely, Ryan R.

    Recent studies revealed layers of enhanced aerosol scattering in the upper troposphere and lower stratosphere over Asia (Asian Tropopause Aerosol Layer (ATAL)) and North America (North American Tropospheric Aerosol Layer (NATAL)). We use a sectional aerosol model (Community Aerosol and Radiation Model for Atmospheres (CARMA)) coupled with the Community Earth System Model version 1 (CESM1) to explore the composition and optical properties of these aerosol layers. The observed aerosol extinction enhancement is reproduced by CESM1/CARMA. Both model and observations indicate a strong gradient of the sulfur-to-carbon ratio from Europe to the Asia on constant pressure surfaces. We found that themore » ATAL is mostly composed of sulfates, surface-emitted organics, and secondary organics; the NATAL is mostly composed of sulfates and secondary organics. In conclusion, the model also suggests that emission increases in Asia between 2000 and 2010 led to an increase of aerosol optical depth of the ATAL by 0.002 on average which is consistent with observations.« less

  10. Dust aerosol and optical properties over North Africa simulated with the ALADIN numerical prediction model from 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Tulet, P.; Fischer, C.; Bouteloup, Y.; Bouyssel, F.; Brachemi, O.

    2015-02-01

    The seasonal cycle and optical properties of mineral dust aerosols in North Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN coupled to the surface scheme SURFEX. The particularity of the simulations is that the major physical processes responsible for dust emission and transport, as well as radiative effects, are taken into account at short timescales and mesoscale resolution. The aim of these simulations is to quantify the dust emission and deposition, locate the major areas of dust emission and establish a climatology of aerosol optical properties in North Africa. The mean monthly Aerosol Optical Thickness (AOT) simulated by ALADIN is compared with the AOTs derived from the standard Dark Target (DT) and Deep Blue (DB) algorithms of the Aqua-MODIS (MODerate resolution Imaging Spectroradiometer) products over North Africa, and with a set of sun photometer measurements located at Banizoumbou, Cinzana, Soroa, Mbour and Capo Verde. The vertical distribution of dust aerosol represented by extinction profiles is also analysed using CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. The annual dust emission simulated by ALADIN over North Africa is 878 Tg year-1. The Bodélé depression appears to be the main area of dust emission in North Africa, with an average estimate of about 21.6 Tg year-1. The simulated AOTs are in good agreement with satellite and sun photometer observations. The positions of the maxima of the modelled AOTs over North Africa match the observed positions, and the ALADIN simulations satisfactorily reproduce the various dust events over the 2006-2010 period. The AOT climatology proposed in this paper provides a solid database of optical properties and consolidates the existing climatology over this region derived from satellites, the AERONET network and Regional Climate Models. Moreover, the three-dimensional distribution of the simulated AOTs also provides information about the

  11. Raman Lidar Measurements of Pinatubo Aerosols over Southeastern Kansas During November-december 1991

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Melfi, S. H.; Whiteman, D. N.; Evans, K. D.

    1992-01-01

    The eruptions of the Philippine volcano Pinatubo during June 1991 produced large amounts of stratospheric aerosols that could significantly affect earth's climate as well as trigger stratospheric ozone depletion through heterogeneous chemical reactions. Information regarding the physical and optical properties of these aerosols is required to quantify those effects. By measuring both the elastically backscattered signal and the inelastic signal produced by Raman scattering from nitrogen molecules, Raman lidar can provide some of this information. In this presentation we discuss Raman lidar measurements of the scattering ratio, backscattering, extinction, extinction/backscattering ratio, and optical thickness of the Pinatubo aerosols over southeastern Kansas made on 10 nights during November and December, 1991. The Raman lidar developed at GSFC is a trailer-based system which uses an XeF excimer laser to transmit light at 351 nm. The light backscattered by molecules and aerosols at this wavelength is detected as well as Raman scattered light from water vapor, nitrogen, and oxygen molecules. Since background skylights interfere with the detection of the Raman signals the data discussed in this paper were acquired only at night.

  12. Aerosol optical properties retrieved from the future space lidar mission ADM-aeolus

    NASA Astrophysics Data System (ADS)

    Martinet, Pauline; Flament, Thomas; Dabas, Alain

    2018-04-01

    The ADM-Aeolus mission, to be launched by end of 2017, will enable the retrieval of aerosol optical properties (extinction and backscatter coefficients essentially) for different atmospheric conditions. A newly developed feature finder (FF) algorithm enabling the detection of aerosol and cloud targets in the atmospheric scene has been implemented. Retrievals of aerosol properties at a better horizontal resolution based on the feature finder groups have shown an improvement mainly on the backscatter coefficient compared to the common 90 km product.

  13. LASE measurements of water vapor and aerosol profiles during the Plains Elevated Convection at Night (PECAN) field experiment

    NASA Astrophysics Data System (ADS)

    Nehrir, A. R.; Ferrare, R. A.; Kooi, S. A.; Butler, C. F.; Notari, A.; Hair, J. W.; Collins, J. E., Jr.; Ismail, S.

    2015-12-01

    The Lidar Atmospheric Sensing Experiment (LASE) system was deployed on the NASA DC-8 aircraft during the Plains Elevated Convection At Night (PECAN) field experiment, which was conducted during June-July 2015 over the central and southern plains. LASE is an active remote sensor that employs the differential absorption lidar (DIAL) technique to measure range resolved profiles of water vapor and aerosols above and below the aircraft. The DC-8 conducted nine local science flights from June 30- July 14 where LASE sampled water vapor and aerosol fields in support of the PECAN primary science objectives relating to better understanding nocturnal Mesoscale Convective Systems (MCSs), Convective Initiation (CI), the Low Level Jet (LLJ), bores, and to compare different airborne and ground based measurements. LASE observed large spatial and temporal variability in water vapor and aerosol distributions in advance of nocturnal MCSs, across bores resulting from MCS outflow boundaries, and across the LLJ associated with the development of MCSs and CI. An overview of the LASE data collected during the PECAN field experiment will be presented where emphasis will be placed on variability of water vapor profiles in the vicinity of severe storms and intense convection in the central and southern plains. Preliminary comparisons show good agreement between coincident LASE and radiosonde water vapor profiles. In addition, an advanced water vapor DIAL system being developed at NASA Langley will be discussed.

  14. Novel Co:MgF2 lidar for aerosol profiler

    NASA Technical Reports Server (NTRS)

    Acharekar, M. A.

    1993-01-01

    Lidars are of great interest because of their unique capabilities in remote sensing applications in sounding of the atmosphere, meteorology, and climatology. In this small business innovative research (SBIR) phase II program, laser sources including Co:MgF2, CTH:YAG, CTH:YSGG, CT:YAG, and Er:Glass were evaluated. Modulator of fused silica and TeO2 materials with Brewster's angle end faces were used with these lasers as acousto-optical (AO) Q-switches. A higher hold-off energy and hence a higher Q-switched energy was obtained by using a high power RF driver. The report provides performance characteristics of these lasers. The tunable (1.75-2.50 microns) Co:MgF2 laser damaged the TeO2 Q-switch cell. However, the CTH:YAG laser operating at 2.09 microns provided output energy of over 300 mJ/p in 50 ns pulse width using the fused silica Q-switch. This Q-switched CTH:YAG laser was used in a breadboard vertical aerosol profiler. A 40 cm diameter telescope, InSb and InGaAs detectors were used in the receiver. The data obtained using this lidar is provided in the report. The data shows that the eye safe lidar using CTH:YAG laser for the vertical aerosol density and range measurements is the viable approach.

  15. Aerosol remote sensing in polar regions

    DOE PAGES

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo; ...

    2015-01-01

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness τ(λ) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent α were calculated. Analysing these data, the monthly mean values of τ(0.50 μm) and α and the relative frequency histograms of the daily mean values of both parameters were determined for winter–spring and summer–autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of α versus τ(0.50 μm) showed: (i)more » a considerable increase in τ(0.50 μm) for the Arctic aerosol from summer to winter–spring, without marked changes in α; and (ii) a marked increase in τ(0.50 μm) passing from the Antarctic Plateau to coastal sites, whereas α decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of τ(λ) and α at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterise vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of τ(λ) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were defined to represent the average features of nuclei

  16. Aerosol remote sensing in polar regions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tomasi, Claudio; Kokhanovsky, Alexander A.; Lupi, Angelo

    Multi-year sets of ground-based sun-photometer measurements conducted at 12 Arctic sites and 9 Antarctic sites were examined to determine daily mean values of aerosol optical thickness τ(λ) at visible and near-infrared wavelengths, from which best-fit values of Ångström's exponent α were calculated. Analysing these data, the monthly mean values of τ(0.50 μm) and α and the relative frequency histograms of the daily mean values of both parameters were determined for winter–spring and summer–autumn in the Arctic and for austral summer in Antarctica. The Arctic and Antarctic covariance plots of the seasonal median values of α versus τ(0.50 μm) showed: (i)more » a considerable increase in τ(0.50 μm) for the Arctic aerosol from summer to winter–spring, without marked changes in α; and (ii) a marked increase in τ(0.50 μm) passing from the Antarctic Plateau to coastal sites, whereas α decreased considerably due to the larger fraction of sea-salt aerosol. Good agreement was found when comparing ground-based sun-photometer measurements of τ(λ) and α at Arctic and Antarctic coastal sites with Microtops measurements conducted during numerous AERONET/MAN cruises from 2006 to 2013 in three Arctic Ocean sectors and in coastal and off-shore regions of the Southern Atlantic, Pacific, and Indian Oceans, and the Antarctic Peninsula. Lidar measurements were also examined to characterise vertical profiles of the aerosol backscattering coefficient measured throughout the year at Ny-Ålesund. Satellite-based MODIS, MISR, and AATSR retrievals of τ(λ) over large parts of the oceanic polar regions during spring and summer were in close agreement with ship-borne and coastal ground-based sun-photometer measurements. An overview of the chemical composition of mode particles is also presented, based on in-situ measurements at Arctic and Antarctic sites. Fourteen log-normal aerosol number size-distributions were defined to represent the average features of nuclei

  17. Short-term Variability of Extinction by Broadband Stellar Photometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Musat, I.C.; Ellingson, R.G.

    2005-03-18

    Aerosol optical depth variation over short-term time intervals is determined from broadband observations of stars with a whole sky imager. The main difficulty in such measurements consists of accurately separating the star flux value from the non-stellar diffuse skylight. Using correction method to overcome this difficulty, the monochromatic extinction at the ground due to aerosols is extracted from heterochromatic measurements. A form of closure is achieved by comparison with simultaneous or temporally close measurements with other instruments, and the total error of the method, as a combination of random error of measurements and systematic error of calibration and model, ismore » assessed as being between 2.6 and 3% rms.« less

  18. A multi-model evaluation of aerosols over South Asia: common problems and possible causes

    NASA Astrophysics Data System (ADS)

    Pan, X.; Chin, M.; Gautam, R.; Bian, H.; Kim, D.; Colarco, P. R.; Diehl, T. L.; Takemura, T.; Pozzoli, L.; Tsigaridis, K.; Bauer, S.; Bellouin, N.

    2015-05-01

    Atmospheric pollution over South Asia attracts special attention due to its effects on regional climate, water cycle and human health. These effects are potentially growing owing to rising trends of anthropogenic aerosol emissions. In this study, the spatio-temporal aerosol distributions over South Asia from seven global aerosol models are evaluated against aerosol retrievals from NASA satellite sensors and ground-based measurements for the period of 2000-2007. Overall, substantial underestimations of aerosol loading over South Asia are found systematically in most model simulations. Averaged over the entire South Asia, the annual mean aerosol optical depth (AOD) is underestimated by a range 15 to 44% across models compared to MISR (Multi-angle Imaging SpectroRadiometer), which is the lowest bound among various satellite AOD retrievals (from MISR, SeaWiFS (Sea-Viewing Wide Field-of-View Sensor), MODIS (Moderate Resolution Imaging Spectroradiometer) Aqua and Terra). In particular during the post-monsoon and wintertime periods (i.e., October-January), when agricultural waste burning and anthropogenic emissions dominate, models fail to capture AOD and aerosol absorption optical depth (AAOD) over the Indo-Gangetic Plain (IGP) compared to ground-based Aerosol Robotic Network (AERONET) sunphotometer measurements. The underestimations of aerosol loading in models generally occur in the lower troposphere (below 2 km) based on the comparisons of aerosol extinction profiles calculated by the models with those from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data. Furthermore, surface concentrations of all aerosol components (sulfate, nitrate, organic aerosol (OA) and black carbon (BC)) from the models are found much lower than in situ measurements in winter. Several possible causes for these common problems of underestimating aerosols in models during the post-monsoon and wintertime periods are identified: the aerosol hygroscopic growth and formation of

  19. Different trends in extreme and median surface aerosol extinction coefficients over China inferred from quality-controlled visibility data

    NASA Astrophysics Data System (ADS)

    Li, Jing; Li, Chengcai; Zhao, Chunsheng

    2018-03-01

    Although the temporal changes in aerosol properties have been widely investigated, the majority of studies has focused on average conditions without much emphasis on the extremes. However, the latter can be more important in terms of human health and climate change. This study uses a previously validated, quality-controlled visibility dataset to investigate the long-term trends (expressed in terms of relative changes) in extreme surface aerosol extinction coefficient (AEC) over China and compares them with the median trends. Two methods are used to independently evaluate the trends, which arrive at consistent results. The signs of extreme and median trends are generally coherent, whereas their magnitudes show distinct spatial and temporal differences. In the 1980s, an overall positive trend is found throughout China with the extreme trend exceeding the mean trend, except for northwest China and the North China Plain. In the 1990s, AEC over northeast and northwest China started to decline while the rest of the country still exhibited an increase. The extreme trends continued to dominate in the south while they yielded to the mean trend in the north. After the year 2000, the extreme trend became weaker than the mean trend overall in terms of both the magnitude and significance level. The annual trend can be primarily attributed to winter and fall trends. The results suggest that the decadal changes in pollution in China may be governed by different mechanisms. Synoptic conditions that often result in extreme air quality changes might have dominated in the 1980s, whereas emission increase might have been the main factor for the 2000s.

  20. New Examination of the Traditional Raman Lidar Technique II: Evaluating the Ratios for Water Vapor and Aerosols

    NASA Technical Reports Server (NTRS)

    Whiteman, David N.

    2003-01-01

    In a companion paper, the temperature dependence of Raman scattering and its influence on the Raman and Rayleigh-Mie lidar equations was examined. New forms of the lidar equation were developed to account for this temperature sensitivity. Here those results are used to derive the temperature dependent forms of the equations for the water vapor mixing ratio, aerosol scattering ratio, aerosol backscatter coefficient, and extinction to backscatter ratio (Sa). The error equations are developed, the influence of differential transmission is studied and different laser sources are considered in the analysis. The results indicate that the temperature functions become significant when using narrowband detection. Errors of 5% and more can be introduced in the water vapor mixing ratio calculation at high altitudes and errors larger than 10% are possible for calculations of aerosol scattering ratio and thus aerosol backscatter coefficient and extinction to backscatter ratio.

  1. Spatial distribution analysis of the OMI aerosol layer height: a pixel-by-pixel comparison to CALIOP observations

    NASA Astrophysics Data System (ADS)

    Chimot, Julien; Pepijn Veefkind, J.; Vlemmix, Tim; Levelt, Pieternel F.

    2018-04-01

    A global picture of atmospheric aerosol vertical distribution with a high temporal resolution is of key importance not only for climate, cloud formation, and air quality research studies but also for correcting scattered radiation induced by aerosols in absorbing trace gas retrievals from passive satellite sensors. Aerosol layer height (ALH) was retrieved from the OMI 477 nm O2 - O2 band and its spatial pattern evaluated over selected cloud-free scenes. Such retrievals benefit from a synergy with MODIS data to provide complementary information on aerosols and cloudy pixels. We used a neural network approach previously trained and developed. Comparison with CALIOP aerosol level 2 products over urban and industrial pollution in eastern China shows consistent spatial patterns with an uncertainty in the range of 462-648 m. In addition, we show the possibility to determine the height of thick aerosol layers released by intensive biomass burning events in South America and Russia from OMI visible measurements. A Saharan dust outbreak over sea is finally discussed. Complementary detailed analyses show that the assumed aerosol properties in the forward modelling are the key factors affecting the accuracy of the results, together with potential cloud residuals in the observation pixels. Furthermore, we demonstrate that the physical meaning of the retrieved ALH scalar corresponds to the weighted average of the vertical aerosol extinction profile. These encouraging findings strongly suggest the potential of the OMI ALH product, and in more general the use of the 477 nm O2 - O2 band from present and future similar satellite sensors, for climate studies as well as for future aerosol correction in air quality trace gas retrievals.

  2. TOMS Validation Based on Profiles of Aerosol Properties in the Lower Troposphere as Obtained with Light Aircraft Systems

    NASA Technical Reports Server (NTRS)

    Prospero, Joseph M.; Maring, Hal; Savoie, Dennis

    2003-01-01

    The goal of the University of Miami Aerosol Group (UMAG) in this project was to make measurements of vertical profiles of aerosol properties and aerosol optical depth using a light aircraft. The UMAG developed a light aircraft aerosol package (LAAP) that was used in light aircraft (Cessna 172) during the Puerto Rico Dust Experiment (PRIDE). This field campaign took place on Puerto Rico during July 2000. Design details and results from the use of the LAAP were presented at TOMS Science team meetings on April 1998, April 1999, and May 2000. Results from the LAAP collected during the PRIDE Experiment were presented at the Fall Meeting of the American Geophysical Union, December 2000. Some of the results from the LAAP collected during the PRIDE Experiment have been accepted for publication in the Journal of Geophysical Research in a "topical section" made up of papers from the PRIDE Program.

  3. Aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing in Guangzhou during the 2006 Pearl River Delta campaign.

    PubMed

    Jung, Jinsang; Lee, Hanlim; Kim, Young J; Liu, Xingang; Zhang, Yuanhang; Gu, Jianwei; Fan, Shaojia

    2009-08-01

    Optical and chemical aerosol measurements were obtained from 2 to 31 July 2006 at an urban site in the metropolitan area of Guangzhou (China) as part of the Program of Regional Integrated Experiment of Air Quality over Pearl River Delta (PRIDE-PRD2006) to investigate aerosol chemistry and the effect of aerosol water content on visibility impairment and radiative forcing. During the PRIDE-PRD2006 campaign, the average contributions of ammonium sulfate, organic mass by carbon (OMC), elemental carbon (EC), and sea salt (SS) to total PM(2.5) mass were measured to be 36.5%, 5.7%, 27.1%, 7.8%, and 3.7%, respectively. Compared with the clean marine period, (NH(4))(2)SO(4), NH(4)NO(3), and OMC were all greatly enhanced (by up to 430%) during local haze periods via the accumulation of a secondary aerosol component. The OMC dominance increased when high levels of biomass burning influenced the measurement site while (NH(4))(2)SO(4) and OMC did when both biomass burning and industrial emissions influenced it. The effect of aerosol water content on the total light-extinction coefficient was estimated to be 34.2%, of which 25.8% was due to aerosol water in (NH(4))(2)SO(4), 5.1% that in NH(4)NO(3), and 3.3% that in SS. The average mass-scattering efficiency (MSE) of PM(10) particles was determined to be 2.2+/-0.6 and 4.6+/-1.7m(2)g(-1) under dry (RH<40%) and ambient conditions, respectively. The average single-scattering albedo (SSA) was 0.80+/-0.08 and 0.90+/-0.04 under dry and ambient conditions, respectively. Not only are the extinction and scattering coefficients greatly enhanced by aerosol water content, but MSE and SSA are also highly sensitive. It can be concluded that sulfate and carbonaceous aerosol, as well as aerosol water content, play important roles in the processes that determine visibility impairment and radiative forcing in the ambient atmosphere of the Guangzhou urban area.

  4. Vertically resolved aerosol properties by multi wavelengths lidar measurements

    NASA Astrophysics Data System (ADS)

    Perrone, M. R.; De Tomasi, F.; Gobbi, G. P.

    2013-07-01

    A new approach is introduced to characterize the dependence on altitude of the aerosol fine mode radius (Rf) and of the fine mode contribution (η) to the aerosol optical thickness (AOT) by three-wavelength lidar measurements. The introduced approach is based on the graphical method of Gobbi et al. (2007), which was applied to AERONET spectral extinction observations and relies on the combined analysis of the Ångstrom exponent (å) and its spectral curvature Δå. Lidar measurements at 355, 532 and 1064 nm were used in this study to retrieve the vertical profiles of å and Δå and to determine the dependence on altitude of Rf and η (532 nm) from the å-Δå combined analysis. Lidar measurements were performed at the Mathematics and Physics Department of Universita' del Salento, in south eastern Italy. Aerosol from continental Europe, the Atlantic, northern Africa, and the Mediterranean Sea are often advected over south eastern Italy and as a consequence, mixed advection patterns leading to aerosol properties varying with altitude are dominant. The proposed approach was applied to eleven measurement days to demonstrate its feasibility in different aerosol load conditions. The selected-days were characterized by AOTs spanning the 0.23-0.67, 0.15-0.41, and 0.04-0.25 range at 355, 532, and 1064 nm, respectively. Lidar ratios varied within the 28-80, 30-70, and 30-55 sr range at 355, 532, and 1064 nm, respectively, for the high variability of the aerosol optical and microphysical properties. å(355 nm, 1064 nm) values retrieved from lidar measurements ranged between 0.12 and 2.5 with mean value ±1 standard deviation equal to 1.4 ± 0.5. Δå varied within the -0.10-0.87 range with mean value equal to 0.1 ± 0.4. Rf and η (532 nm) values spanning the 0.02-0.30 μm and the 0.30-0.99 range, respectively were associated to the å-Δå data points. Rf and η values showed no dependence on the altitude. 72% of the data points were in the Δå-å space delimited by the

  5. In Situ Aerosol Detector

    NASA Technical Reports Server (NTRS)

    Vakhtin, Andrei; Krasnoperov, Lev

    2011-01-01

    An affordable technology designed to facilitate extensive global atmospheric aerosol measurements has been developed. This lightweight instrument is compatible with newly developed platforms such as tethered balloons, blimps, kites, and even disposable instruments such as dropsondes. This technology is based on detection of light scattered by aerosol particles where an optical layout is used to enhance the performance of the laboratory prototype instrument, which allows detection of smaller aerosol particles and improves the accuracy of aerosol particle size measurement. It has been determined that using focused illumination geometry without any apertures is advantageous over using the originally proposed collimated beam/slit geometry (that is supposed to produce uniform illumination over the beam cross-section). The illumination source is used more efficiently, which allows detection of smaller aerosol particles. Second, the obtained integral scattered light intensity measured for the particle can be corrected for the beam intensity profile inhomogeneity based on the measured beam intensity profile and measured particle location. The particle location (coordinates) in the illuminated sample volume is determined based on the information contained in the image frame. The procedure considerably improves the accuracy of determination of the aerosol particle size.

  6. Role of interfacial water in the heterogeneous uptake of glyoxal by mixed glycine and ammonium sulfate aerosols.

    PubMed

    Trainic, Miri; Riziq, Ali Abo; Lavi, Avi; Rudich, Yinon

    2012-06-21

    This study focuses on the heterogeneous reactions of gas phase glyoxal with aerosols of glycine, the most abundant amino acid in atmospheric aerosols, as well as with a mixture of glycine and ammonium sulfate (AS) at a molar ratio of 1:100 (glycine-AS 1:100). Aerosols were exposed to varying relative humidity (RH) conditions in the presence of gas phase glyoxal for ∼1 h, followed by drying and efflorescence. The changes in size, chemical composition, and optical properties were consequently measured. The reactions occur over a wide range of relative humidities, from ∼30% up to 90% RH, covering values that are substantially lower as well as above the deliquescence point of the investigated aerosols. The product aerosols exhibit a trend of increasing growth in size, in optical extinction cross sections, and in extinction efficiencies (at λ = 355 nm) with decreasing seed aerosol size, and with decreasing RH values from 90% to ∼50%. For glycine-AS 1:100 particles, the ratio of the geometric cross section of the product aerosol to the original seed aerosol reached a value of ∼3, the optical extinction cross section ratio was up to ∼25, and the Q(ext) ratio was up to ∼8, exceeding those of both AS and glycine separately, suggesting a synergistic effect. Aerosol mass spectrometer analyses show that the main products of all the studied reactions are glyoxal oligomers (light scattering compounds), with a minor contribution from imidazoles (absorbing compounds at λ = 355 nm). These findings imply that the changes in the optical properties are likely due to enhanced scattering by the reaction products. The fraction of absorbing substances in the reacted aerosol increases with increasing RH, suggesting that the absorption component may become more substantial after longer reaction times, possibly in cloud or fog droplets. The results suggest that these reactions are possibly important in low RH regions, plausibly due to the reaction occurring in a few interfacial

  7. Profiling of Atmospheric Water Vapor with MIR and LASE

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Racette, P.; Triesly, M. E.; Browell, E. V.; Ismail, S.; Chang, L. A.; Hildebrand, Peter H. (Technical Monitor)

    2001-01-01

    This paper presents the first and the only simultaneous measurements of water vapor by MIR (Millimeter-wave Imaging Radiometer) and LASE (Lidar Atmospheric Sounding Experiment) on board the same ER-2 aircraft. Water vapor is one of the most important constituents in the Earth's atmosphere, as its spatial and temporal variations affect a wide spectrum of meteorological phenomena ranging from the formation of clouds to the development of severe storms. Its concentration, as measured in terms of relative humidity, determines the extinction coefficient of atmospheric aerosol particles and therefore visibility. These considerations point to the need for effective and frequent measurements of the atmospheric water vapor. The MIR and LASE instruments provide measurements of water vapor profiles with two markedly different techniques. LASE can give water vapor profiles with excellent vertical resolution under clear condition, while MIR can retrieve water vapor profiles with a crude vertical resolution even under a moderate cloud cover. Additionally, millimeter-wave measurements are relatively simple and provide better spatial coverage.

  8. Measurements of the absorption coefficient of stratospheric aerosols

    NASA Technical Reports Server (NTRS)

    Ogren, J. A.; Ahlquist, N. C.; Clarke, A. D.; Charlson, R. J.

    1981-01-01

    The absorption coefficients of stratospheric aerosols are measured using a variation on the integrating plate method. The technique is based on the decrease in the transparency of a substrate when an absorbing aerosol is deposited on it. A Lambert scatterer is placed behind the substrate to integrate forward scattered light and minimize the effect of scattering on the measurement. The low pressure in the stratosphere is used for the direct impaction of particles onto a narrow strip of opal glass. The eight samples collected had a median value of 4 x 10 to the -9th m with an uncertainty of + or - 5 x 10 to the -9th m. If this absorption is due to graphitic carbon, then its concentration is estimated at about 0.4 ng/cu m, or about 0.25% of the total aerosol mass concentration. Estimates of the aerosol scattering coefficients based on satellite extinction inversions result in an aerosol single-scattering albedo in the range of 0.96-1.0.

  9. Global Monitoring of Clouds and Aerosols Using a Network of Micro-Pulse Lidar Systems

    NASA Technical Reports Server (NTRS)

    Welton, Ellsworth J.; Campbell, James R.; Spinhirne, James D.; Scott, V. Stanley

    2000-01-01

    Long-term global radiation programs, such as AERONET and BSRN, have shown success in monitoring column averaged cloud and aerosol optical properties. Little attention has been focused on global measurements of vertically resolved optical properties. Lidar systems are the preferred instrument for such measurements. However, global usage of lidar systems has not been achieved because of limits imposed by older systems that were large, expensive, and logistically difficult to use in the field. Small, eye-safe, and autonomous lidar systems are now currently available and overcome problems associated with older systems. The first such lidar to be developed is the Micro-pulse lidar System (MPL). The MPL has proven to be useful in the field because it can be automated, runs continuously (day and night), is eye-safe, can easily be transported and set up, and has a small field-of-view which removes multiple scattering concerns. We have developed successful protocols to operate and calibrate MPL systems. We have also developed a data analysis algorithm that produces data products such as cloud and aerosol layer heights, optical depths, extinction profiles, and the extinction-backscatter ratio. The algorithm minimizes the use of a priori assumptions and also produces error bars for all data products. Here we present an overview of our MPL protocols and data analysis techniques. We also discuss the ongoing construction of a global MPL network in conjunction with the AERONET program. Finally, we present some early results from the MPL network.

  10. Estimation and Bias Correction of Aerosol Abundance using Data-driven Machine Learning and Remote Sensing

    NASA Technical Reports Server (NTRS)

    Malakar, Nabin K.; Lary, D. L.; Moore, A.; Gencaga, D.; Roscoe, B.; Albayrak, Arif; Petrenko, Maksym; Wei, Jennifer

    2012-01-01

    Air quality information is increasingly becoming a public health concern, since some of the aerosol particles pose harmful effects to peoples health. One widely available metric of aerosol abundance is the aerosol optical depth (AOD). The AOD is the integrated light extinction coefficient over a vertical atmospheric column of unit cross section, which represents the extent to which the aerosols in that vertical profile prevent the transmission of light by absorption or scattering. The comparison between the AOD measured from the ground-based Aerosol Robotic Network (AERONET) system and the satellite MODIS instruments at 550 nm shows that there is a bias between the two data products. We performed a comprehensive analysis exploring possible factors which may be contributing to the inter-instrumental bias between MODIS and AERONET. The analysis used several measured variables, including the MODIS AOD, as input in order to train a neural network in regression mode to predict the AERONET AOD values. This not only allowed us to obtain an estimate, but also allowed us to infer the optimal sets of variables that played an important role in the prediction. In addition, we applied machine learning to infer the global abundance of ground level PM2.5 from the AOD data and other ancillary satellite and meteorology products. This research is part of our goal to provide air quality information, which can also be useful for global epidemiology studies.

  11. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-11-01

    Multi-wavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentration profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analysed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical in distinguishing between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  12. Assessment of aerosol's mass concentrations from measured linear particle depolarization ratio (vertically resolved) and simulations

    NASA Astrophysics Data System (ADS)

    Nemuc, A.; Vasilescu, J.; Talianu, C.; Belegante, L.; Nicolae, D.

    2013-06-01

    Multiwavelength depolarization Raman lidar measurements from Magurele, Romania are used in this study along with simulated mass-extinction efficiencies to calculate the mass concentrations profiles of different atmospheric components, due to their different depolarization contribution to the 532 nm backscatter coefficient. Linear particle depolarization ratio (δpart) was computed using the relative amplification factor and the system-dependent molecular depolarization. The low depolarizing component was considered as urban/smoke, with a mean δpart of 3%, while for the high depolarizing component (mineral dust) a mean δpart of 35% was assumed. For this study 11 months of lidar measurements were analyzed. Two study cases are presented in details: one for a typical Saharan dust aerosol intrusion, 10 June 2012 and one for 12 July 2012 when a lofted layer consisting of biomass burning smoke extended from 3 to 4.5 km height. Optical Properties of Aerosols and Clouds software package (OPAC) classification and conversion factors were used to calculate mass concentrations. We found that calibrated depolarization measurements are critical to distinguish between smoke-reach aerosol during the winter and dust-reach aerosol during the summer, as well as between elevated aerosol layers having different origins. Good agreement was found between lidar retrievals and DREAM- Dust REgional Atmospheric Model forecasts in cases of Saharan dust. Our method was also compared against LIRIC (The Lidar/Radiometer Inversion Code) and very small differences were observed.

  13. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

    NASA Astrophysics Data System (ADS)

    Mallet, M.; Dulac, F.; Formenti, P.; Nabat, P.; Sciare, J.; Roberts, G.; Pelon, J.; Ancellet, G.; Tanré, D.; Parol, F.; di Sarra, A.; Alados, L.; Arndt, J.; Auriol, F.; Blarel, L.; Bourrianne, T.; Brogniez, G.; Chazette, P.; Chevaillier, S.; Claeys, M.; D'Anna, B.; Denjean, C.; Derimian, Y.; Desboeufs, K.; Di Iorio, T.; Doussin, J.-F.; Durand, P.; Féron, A.; Freney, E.; Gaimoz, C.; Goloub, P.; Gómez-Amo, J. L.; Granados-Muñoz, M. J.; Grand, N.; Hamonou, E.; Jankowiak, I.; Jeannot, M.; Léon, J.-F.; Maillé, M.; Mailler, S.; Meloni, D.; Menut, L.; Momboisse, G.; Nicolas, J.; Podvin, J.; Pont, V.; Rea, G.; Renard, J.-B.; Roblou, L.; Schepanski, K.; Schwarzenboeck, A.; Sellegri, K.; Sicard, M.; Solmon, F.; Somot, S.; Torres, B.; Totems, J.; Triquet, S.; Verdier, N.; Verwaerde, C.; Wenger, J.; Zapf, P.

    2015-07-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Forcing on the Mediterranean Climate (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental set-up also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modelling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to produce high level of atmospheric pollutants nor

  14. De-coupling interannual variations of vertical dust extinction over the Taklimakan Desert during 2007-2016 using CALIOP.

    PubMed

    Nan, Yang; Wang, Yuxuan

    2018-03-26

    During the springtime, mineral dust from the Taklimakan Desert (TD) is lifted up to high altitudes and transported long distances by the westerlies. The vertical distributions of Taklimakan dust are important for both long-range transport and climate effects. In this study, we use CALIOP Level 3 dust extinction to describe interannual variation of dust extinction in TD aggregated at each 1km interval (1-2km, 2-3km, 3-4km, 4-5km and 5-6km) above mean sea level during springtime from 2007 to 2016. 87% of dust extinction over TD is concentrated at 1-4km taking a major composition of dust aerosol optical depth (AOD) and only 8.1% dust AOD is at 4-6km. Interannual variation of seasonal and monthly dust extinction at 1-4km is almost as same as dust AOD (R>0.99) but different from that at 4-6km (R are around 0.42). Our analysis provides observational evidence from CALIOP that vertical dust extinction over TD has distinctively different variability below and above 4km altitude and this threshold divides dust transport in TD into two systems. Taklimakan dust aerosols are more related to dust transport at high altitudes (4-10km) than low altitudes (0-4km) over downwind regions. High dust extinction below 4km over TD is necessary but not sufficient conditions to ensure dust transport easterly, while high dust extinction levels at 4-6km over TD are both necessary and sufficient conditions; such contrast leads to the de-coupled interannual variability seen by CALIOP. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Long-term profiling of mineral dust and pollution aerosol with multiwavelength polarization Raman lidar at the Central Asian site of Dushanbe, Tajikistan: case studies

    NASA Astrophysics Data System (ADS)

    Hofer, Julian; Althausen, Dietrich; Abdullaev, Sabur F.; Makhmudov, Abduvosit N.; Nazarov, Bakhron I.; Schettler, Georg; Engelmann, Ronny; Baars, Holger; Wadinga Fomba, K.; Müller, Konrad; Heinold, Bernd; Kandler, Konrad; Ansmann, Albert

    2017-12-01

    For the first time, continuous vertically resolved aerosol measurements were performed by lidar in Tajikistan, Central Asia. Observations with the multiwavelength polarization Raman lidar PollyXT were conducted during CADEX (Central Asian Dust EXperiment) in Dushanbe, Tajikistan, from March 2015 to August 2016. Co-located with the lidar, a sun photometer was also operated. The goal of CADEX is to provide an unprecedented data set on vertically resolved aerosol optical properties in Central Asia, an area highly affected by climate change but largely missing vertically resolved aerosol measurements. During the 18-month measurement campaign, mineral dust was detected frequently from ground to the cirrus level height. In this study, an overview of the measurement period is given and four typical but different example measurement cases are discussed in detail. Three of them are dust cases and one is a contrasting pollution aerosol case. Vertical profiles of the measured optical properties and the calculated dust and non-dust mass concentrations are presented. Dust source regions were identified by means of backward trajectory analyses. A lofted layer of Middle Eastern dust with an aerosol optical thickness (AOT) of 0.4 and an extinction-related Ångström exponent of 0.41 was measured. In comparison, two near-ground dust cases have Central Asian sources. One is an extreme dust event with an AOT of 1.5 and Ångström exponent of 0.12 and the other one is a most extreme dust event with an AOT of above 4 (measured by sun photometer) and an Ångström exponent of -0.08. The observed lidar ratios (and particle linear depolarization ratios) in the presented dust cases range from 40.3 to 46.9 sr (and 0.18-0.29) at 355 nm and from 35.7 to 42.9 sr (0.31-0.35) at 532 nm wavelength. The particle linear depolarization ratios indicate almost unpolluted dust in the case of a lofted dust layer and pure dust in the near-ground dust cases. The lidar ratio values are lower than typical

  16. Global direct radiative forcing by process-parameterized aerosol optical properties

    NASA Astrophysics Data System (ADS)

    KirkevâG, Alf; Iversen, Trond

    2002-10-01

    A parameterization of aerosol optical parameters is developed and implemented in an extended version of the community climate model version 3.2 (CCM3) of the U.S. National Center for Atmospheric Research. Direct radiative forcing (DRF) by monthly averaged calculated concentrations of non-sea-salt sulfate and black carbon (BC) is estimated. Inputs are production-specific BC and sulfate from [2002] and background aerosol size distribution and composition. The scheme interpolates between tabulated values to obtain the aerosol single scattering albedo, asymmetry factor, extinction coefficient, and specific extinction coefficient. The tables are constructed by full calculations of optical properties for an array of aerosol input values, for which size-distributed aerosol properties are estimated from theory for condensation and Brownian coagulation, assumed distribution of cloud-droplet residuals from aqueous phase oxidation, and prescribed properties of the background aerosols. Humidity swelling is estimated from the Köhler equation, and Mie calculations finally yield spectrally resolved aerosol optical parameters for 13 solar bands. The scheme is shown to give excellent agreement with nonparameterized DRF calculations for a wide range of situations. Using IPCC emission scenarios for the years 2000 and 2100, calculations with an atmospheric global cliamte model (AFCM) yield a global net anthropogenic DRF of -0.11 and 0.11 W m-2, respectively, when 90% of BC from biomass burning is assumed anthropogenic. In the 2000 scenario, the individual DRF due to sulfate and BC has separately been estimated to -0.29 and 0.19 W m-2, respectively. Our estimates of DRF by BC per BC mass burden are lower than earlier published estimates. Some sensitivity tests are included to investigate to what extent uncertain assumptions may influence these results.

  17. An Analysis of AERONET Aerosol Absorption Properties and Classifications Representative of Aerosol Source Regions

    NASA Technical Reports Server (NTRS)

    Giles, David M.; Holben, Brent N.; Eck, Thomas F.; Sinyuk, Aliaksandr; Smirnov, Alexander; Slutsker, Ilya; Dickerson, R. R.; Thompson, A. M.; Schafer, J. S.

    2012-01-01

    Partitioning of mineral dust, pollution, smoke, and mixtures using remote sensing techniques can help improve accuracy of satellite retrievals and assessments of the aerosol radiative impact on climate. Spectral aerosol optical depth (tau) and single scattering albedo (omega (sub 0) ) from Aerosol Robotic Network (AERONET) measurements are used to form absorption [i.e., omega (sub 0) and absorption Angstrom exponent (alpha(sub abs))] and size [i.e., extinction Angstrom exponent (alpha(sub ext)) and fine mode fraction of tau] relationships to infer dominant aerosol types. Using the long-term AERONET data set (1999-2010), 19 sites are grouped by aerosol type based on known source regions to: (1) determine the average omega (sub 0) and alpha(sub abs) at each site (expanding upon previous work); (2) perform a sensitivity study on alpha(sub abs) by varying the spectral omega (sub 0); and (3) test the ability of each absorption and size relationship to distinguish aerosol types. The spectral omega (sub 0) averages indicate slightly more aerosol absorption (i.e., a 0.0 < delta omega (sub 0) <= 0.02 decrease) than in previous work and optical mixtures of pollution and smoke with dust show stronger absorption than dust alone. Frequency distributions of alpha(sub abs) show significant overlap among aerosol type categories and at least 10% of the alpha(sub abs) retrievals in each category are below 1.0. Perturbing the spectral omega (sub 0) by +/- 0.03 induces significant alpha(sub abs) changes from the unperturbed value by at least approx. +/- 0.6 for Dust, approx. +/-0.2 for Mixed, and approx. +/-0.1 for Urban/Industrial and Biomass Burning. The omega (sub 0)440nm and alpha(sub ext) 440-870nm relationship shows the best separation among aerosol type clusters, providing a simple technique for determining aerosol type from surface- and future space-based instrumentation.

  18. Rainfall-aerosol relationships explained by wet scavenging and humidity

    NASA Astrophysics Data System (ADS)

    Grandey, Benjamin S.; Gururaj, Anisha; Stier, Philip; Wagner, Till M.

    2014-08-01

    Relationships between precipitation rate and aerosol optical depth, the extinction of light by aerosol in an atmospheric column, have been observed in satellite-retrieved data. What are the reasons for these precipitation-aerosol relationships? We investigate relationships between convective precipitation rate (Rconv) and aerosol optical depth (τtot) using the ECHAM5-HAM aerosol-climate model. We show that negative Rconv-τtot relationships arise due to wet scavenging of aerosol. The apparent lack of negative Rconv-τtot relationships in satellite-retrieved data is likely because the satellite data do not sample wet scavenging events. When convective wet scavenging is excluded in the model, we find positive Rconv-τtot relationships in regions where convective precipitation is the dominant form of model precipitation. The spatial distribution of these relationships is in good agreement with satellite-based results. We further demonstrate that a substantial component of these positive relationships arises due to covariation with large-scale relative humidity. Although the interpretation of precipitation-aerosol relationships remains a challenging question, we suggest that progress can be made through a synergy between observations and models.

  19. Lidar Measurements of the Vertical Distribution of Aerosol Optical and Physical Properties over Central Asia

    DOE PAGES

    Chen, Boris B.; Sverdlik, Leonid G.; Imashev, Sanjar A.; ...

    2013-01-01

    The vertical structure of aerosol optical and physical properties was measured by Lidar in Eastern Kyrgyzstan, Central Asia, from June 2008 to May 2009. Lidar measurements were supplemented with surface-based measurements of PM 2.5 and PM 10 mass and chemical composition in both size fractions. Dust transported into the region is common, being detected 33% of the time. The maximum frequency occurred in the spring of 2009. Dust transported to Central Asia comes from regional sources, for example, Taklimakan desert and Aral Sea basin, and from long-range transport, for example, deserts of Arabia, Northeast Africa, Iran, and Pakistan. Regional sourcesmore » are characterized by pollution transport with maximum values of coarse particles within the planetary boundary layer, aerosol optical thickness, extinction coefficient, integral coefficient of aerosol backscatter, and minimum values of the Ångström exponent. Pollution associated with air masses transported over long distances has different characteristics during autumn, winter, and spring. During winter, dust emissions were low resulting in high values of the Ångström exponent (about 0.51) and the fine particle mass fraction (64%). Dust storms were more frequent during spring with an increase in coarse dust particles in comparison to winter. The aerosol vertical profiles can be used to lower uncertainty in estimating radiative forcing.« less

  20. Investigation of multiple scattering effects in aerosols

    NASA Technical Reports Server (NTRS)

    Deepak, A.

    1980-01-01

    The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

  1. Investigation of multiple scattering effects in aerosols

    NASA Astrophysics Data System (ADS)

    Deepak, A.

    1980-05-01

    The results are presented of investigations on the various aspects of multiple scattering effects on visible and infrared laser beams transversing dense fog oil aerosols contained in a chamber (4' x 4' x 9'). The report briefly describes: (1) the experimental details and measurements; (2) analytical representation of the aerosol size distribution data by two analytical models (the regularized power law distribution and the inverse modified gamma distribution); (3) retrieval of aerosol size distributions from multispectral optical depth measurements by two methods (the two and three parameter fast table search methods and the nonlinear least squares method); (4) modeling of the effects of aerosol microphysical (coagulation and evaporation) and dynamical processes (gravitational settling) on the temporal behavior of aerosol size distribution, and hence on the extinction of four laser beams with wavelengths 0.44, 0.6328, 1.15, and 3.39 micrometers; and (5) the exact and approximate formulations for four methods for computing the effects of multiple scattering on the transmittance of laser beams in dense aerosols, all of which are based on the solution of the radiative transfer equation under the small angle approximation.

  2. The Potential of The Synergy of Sunphotometer and Lidar Data to Validate Vertical Profiles of The Aerosol Mass Concentration Estimated by An Air Quality Model

    NASA Astrophysics Data System (ADS)

    Siomos, N.; Filioglou, M.; Poupkou, A.; Liora, N.; Dimopoulos, S.; Melas, D.; Chaikovsky, A.; Balis, D. S.

    2016-06-01

    Vertical profiles of the aerosol mass concentration derived by the Lidar/Radiometer Inversion Code (LIRIC), that uses combined sunphotometer and lidar data, were used in order to validate the aerosol mass concentration profiles estimated by the air quality model CAMx. Lidar and CIMEL measurements performed at the Laboratory of Atmospheric Physics of the Aristotle University of Thessaloniki, Greece (40.5N, 22.9E) from the period 2013-2014 were used in this study.

  3. Lower tropospheric distributions of O3 and aerosol over Raoyang, a rural site in the North China Plain

    NASA Astrophysics Data System (ADS)

    Wang, Rui; Xu, Xiaobin; Jia, Shihui; Ma, Ruisheng; Ran, Liang; Deng, Zhaoze; Lin, Weili; Wang, Ying; Ma, Zhiqiang

    2017-03-01

    The North China Plain (NCP) has become one of the most polluted regions in China, with the rapidly increasing economic growth in the past decades. High concentrations of ambient O3 and aerosol have been observed at urban as well as rural sites in the NCP. Most of the in situ observations of air pollutants have been conducted near the ground so that current knowledge about the vertical distributions of tropospheric O3 and aerosol over the NCP region is still limited. In this study, vertical profiles of O3 and size-resolved aerosol concentrations below 2.5 km were measured in summer 2014 over a rural site in the NCP, using an unmanned aerial vehicle (UAV) equipped with miniature analyzers. In addition, vertical profiles of aerosol scattering property in the lower troposphere and vertical profiles of O3 below 1 km were also observed at the site using a lidar and tethered balloon, respectively. The depths of the mixed layer and residual layer were determined according to the vertical gradients of lidar particle extinction and aerosol number concentration. Average O3 and size-resolved aerosol number concentration in both the mixed and residual layer were obtained from the data observed in seven UAV flights. The results show that during most of the flights the O3 levels above the top of mixed layer were higher than those below. Such a positive gradient in the vertical distribution of O3 makes the residual layer an important source of O3 in the mixed layer, particularly during the morning when the top of mixed layer is rapidly elevated. In contrast to O3, aerosol number concentration was normally higher in the mixed layer than in the residual layer, particularly in the early morning. Aerosol particles were overwhelmingly distributed in the size range < 1 µm, showing slight differences between the mixed and residual layers. Our measurements confirm that the lower troposphere over the rural area of the NCP is largely impacted by anthropogenic pollutants locally emitted or

  4. Global volcanic aerosol properties derived from emissions, 1990-2015, using CESM1(WACCM)

    NASA Astrophysics Data System (ADS)

    Mills, Michael; Schmidt, Anja; Easter, Richard; Solomon, Susan; Kinnison, Douglas; Ghan, Steven; Neely, Ryan; Marsh, Daniel; Conley, Andrew; Bardeen, Charles; Gettelman, Andrew

    2016-04-01

    Accurate representation of global stratospheric aerosols from volcanic and non-volcanic sulfur emissions is key to understanding the cooling effects and ozone-losses that may be linked to volcanic activity. Attribution of climate variability to volcanic activity is of particular interest in relation to the post-2000 slowing in the rate of global average temperature increases. We have compiled a database of volcanic SO2 emissions and plume altitudes for eruptions from 1990 to 2015, and developed a new prognostic capability for simulating stratospheric sulfate aerosols in the Community Earth System Model (CESM). We combined these with other non-volcanic emissions of sulfur sources to reconstruct global aerosol properties from 1990 to 2015. Our calculations show remarkable agreement with ground-based lidar observations of stratospheric aerosol optical depth (SAOD), and with in situ measurements of stratospheric aerosol surface area density (SAD). These properties are key parameters in calculating the radiative and chemical effects of stratospheric aerosols. Our SAOD calculations represent a clear improvement over available satellite-based analyses, which generally ignore aerosol extinction below 15 km, a region that can contain the vast majority of stratospheric aerosol extinction at mid- and high-latitudes. Our SAD calculations greatly improve on that provided for the Chemistry-Climate Model Initiative, which misses about 60% of the SAD measured in situ on average during both volcanically active and volcanically quiescent periods. The stark differences in SAOD and SAD compared to other data sets will have significant effects on calculations of the radiative forcing of climate and global stratospheric chemistry over the period 2005-2015. In light of these results, the impact of volcanic aerosols in reducing the rate of global average temperature increases since the year 2000 should be revisited. We have made our calculated aerosol properties from January 1990 to

  5. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Dubovik, Oleg; Holben, Brent; Torres, Omar; Anderson, Tad; Quinn, Patricia; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET, satellite retrievals from the TOMS instrument, and field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption. and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  6. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2003-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine what are the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  7. Aerosol Absorption in the Atmosphere: Perspectives from Global Model, Ground-Based Measurements, and Field Observations

    NASA Technical Reports Server (NTRS)

    Chin, Main; Dubovik, Oleg; Holben, Brent; Anderson, Tad; Quinn, Patricia; Duncan, Bryan; Ginoux, Paul

    2004-01-01

    Aerosol absorption in the atmosphere poses a major uncertainty in assessing the aerosol climate effects. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, and our limited knowledge of aerosol mixing state and optical properties. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt. We compare the model calculated total aerosol optical thickness, extinction, and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia. We will examine the most sensitive factors in determining the aerosol absorption, and the consequences of assessing the aerosol radiative forcing and atmospheric heating associated with those factors.

  8. Aerosol absorption profiling from the synergy of lidar and sun-photometry: the ACTRIS-2 campaigns in Germany, Greece and Cyprus

    NASA Astrophysics Data System (ADS)

    Tsekeri, Alexandra; Amiridis, Vassilis; Lopatin, Anton; Marinou, Eleni; Giannakaki, Eleni; Pikridas, Michael; Sciare, Jean; Liakakou, Eleni; Gerasopoulos, Evangelos; Duesing, Sebastian; Corbin, Joel C.; Gysel, Martin; Bukowiecki, Nicolas; Baars, Holger; Engelmann, Ronny; Wehner, Birgit; Kottas, Michael; Mamali, Dimitra; Kokkalis, Panagiotis; Raptis, Panagiotis I.; Stavroulas, Iasonas; Keleshis, Christos; Müller, Detlef; Solomos, Stavros; Binietoglou, Ioannis; Mihalopoulos, Nikolaos; Papayannis, Alexandros; Stachlewska, Iwona S.; Igloffstein, Julia; Wandinger, Ulla; Ansmann, Albert; Dubovik, Oleg; Goloub, Philippe

    2018-04-01

    Aerosol absorption profiling is crucial for radiative transfer calculations and climate modelling. Here, we utilize the synergy of lidar with sun-photometer measurements to derive the absorption coefficient and single scattering albedo profiles during the ACTRIS-2 campaigns held in Germany, Greece and Cyprus. The remote sensing techniques are compared with in situ measurements in order to harmonize and validate the different methodologies and reduce the absorption profiling uncertainties.

  9. Vertical distribution of aerosols in the vicinity of Mexico City during MILAGRO-2006 Campaign

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lewandowski, P.A.; Kleinman, L.; Eichinger, W. E.

    On 7 March 2006, a mobile, ground-based, vertical pointing, elastic lidar system made a North-South transect through the Mexico City basin. Column averaged, aerosol size distribution (ASD) measurements were made on the ground concurrently with the lidar measurements. The ASD ground measurements allowed calculation of the column averaged mass extinction efficiency (MEE) for the lidar system (1064 nm). The value of column averaged MEE was combined with spatially resolved lidar extinction coefficients to produce total aerosol mass concentration estimates with the resolution of the lidar (1.5 m vertical spatial and 1 s temporal). Airborne ASD measurements from DOE G-1 aircraftmore » made later in the day on 7 March 2006, allowed the evaluation of the assumptions of constant ASD with height and time used for estimating the column averaged MEE. The results showed that the aerosol loading within the basin is about twice what is observed outside of the basin. The total aerosol base concentrations observed in the basin are of the order of 200 {mu}g/m{sup 3} and the base levels outside are of the order of 100 {mu}g/m{sup 3}. The local heavy traffic events can introduce aerosol levels near the ground as high as 900 {mu}g/m{sup 3}. The article presents the methodology for estimating aerosol mass concentration from mobile, ground-based lidar measurements in combination with aerosol size distribution measurements. An uncertainty analysis of the methodology is also presented.« less

  10. Aerosol climate time series from ESA Aerosol_cci (Invited)

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.

    2013-12-01

    Within the ESA Climate Change Initiative (CCI) the Aerosol_cci project (mid 2010 - mid 2013, phase 2 proposed 2014-2016) has conducted intensive work to improve algorithms for the retrieval of aerosol information from European sensors AATSR (3 algorithms), PARASOL, MERIS (3 algorithms), synergetic AATSR/SCIAMACHY, OMI and GOMOS. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Angstrom coefficient were retrieved from the other sensors. Global datasets for 2008 were produced and validated versus independent ground-based data and other satellite data sets (MODIS, MISR). An additional 17-year dataset is currently generated using ATSR-2/AATSR data. During the three years of the project, intensive collaborative efforts were made to improve the retrieval algorithms focusing on the most critical modules. The team agreed on the use of a common definition for the aerosol optical properties. Cloud masking was evaluated, but a rigorous analysis with a pre-scribed cloud mask did not lead to improvement for all algorithms. Better results were obtained using a post-processing step in which sudden transitions, indicative of possible occurrence of cloud contamination, were removed. Surface parameterization, which is most critical for the nadir only algorithms (MERIS and synergetic AATSR / SCIAMACHY) was studied to a limited extent. The retrieval results for AOD, Ångström exponent (AE) and uncertainties were evaluated by comparison with data from AERONET (and a limited amount of MAN) sun photometer and with satellite data available from MODIS and MISR. Both level2 and level3 (gridded daily) datasets were validated. Several validation metrics were used (standard statistical quantities such as bias, rmse, Pearson correlation, linear regression, as well as scoring approaches to quantitatively evaluate the spatial and temporal correlations against AERONET), and in some cases

  11. Aerosol Profile Retrievals from Integrated Dual Wavelengths Space Lidar ESSP3-CENA and Spectral Radiance MODIS Data

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Mattoo, Shana; Tanre, Didier; Kleidman, Richard; Lau, William K. M. (Technical Monitor)

    2001-01-01

    The ESSP3-CENA space mission (formally PICASSO-CENA) will provide continues global observations with a two wavelength lidar. The attenuated backscattering coefficients measured by the lidar, have valuable information about the vertical distribution of aerosol particles and their sizes. However the information cannot be mapped into unique aerosol physical properties. Infinite number of physical solutions with different attenuations through the atmosphere can reconstruct the same two wavelength backscattered profile measured from space. Spectral radiance measured by MODIS simultaneously with the ESSP3 data can constrain the problem and resolve this ambiguity to a large extent. Sensitivity study shows that inversion of the integrated MODIS+ESSP3 data can derive the vertical profiles of the fine and coarse modes mixed in the same atmospheric column in the presence of moderate calibration uncertainties and electronic noise (approx. 10%). We shall present the sensitivity study and results from application of the technique to measurements in the SAFARI-2000 and SHADE experiments.

  12. Satellite stratospheric aerosol measurement validation

    NASA Technical Reports Server (NTRS)

    Russell, P. B.; Mccormick, M. P.

    1984-01-01

    The validity of the stratospheric aerosol measurements made by the satellite sensors SAM II and SAGE was tested by comparing their results with each other and with results obtained by other techniques (lider, dustsonde, filter, and impactor). The latter type of comparison required the development of special techniques that convert the quantity measured by the correlative sensor (e.g. particle backscatter, number, or mass) to that measured by the satellite sensor (extinction) and quantitatively estimate the uncertainty in the conversion process. The results of both types of comparisons show agreement within the measurement and conversion uncertainties. Moreover, the satellite uncertainty is small compared to aerosol natural variability (caused by seasonal changes, volcanoes, sudden warmings, and vortex structure). It was concluded that the satellite measurements are valid.

  13. Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation

    NASA Astrophysics Data System (ADS)

    Geisinger, Armin; Behrendt, Andreas; Wulfmeyer, Volker; Strohbach, Jens; Förstner, Jochen; Potthast, Roland

    2017-12-01

    A new backscatter lidar forward operator was developed which is based on the distinct calculation of the aerosols' backscatter and extinction properties. The forward operator was adapted to the COSMO-ART ash dispersion simulation of the Eyjafjallajökull eruption in 2010. While the particle number concentration was provided as a model output variable, the scattering properties of each individual particle type were determined by dedicated scattering calculations. Sensitivity studies were performed to estimate the uncertainties related to the assumed particle properties. Scattering calculations for several types of non-spherical particles required the usage of T-matrix routines. Due to the distinct calculation of the backscatter and extinction properties of the models' volcanic ash size classes, the sensitivity studies could be made for each size class individually, which is not the case for forward models based on a fixed lidar ratio. Finally, the forward-modeled lidar profiles have been compared to automated ceilometer lidar (ACL) measurements both qualitatively and quantitatively while the attenuated backscatter coefficient was chosen as a suitable physical quantity. As the ACL measurements were not calibrated automatically, their calibration had to be performed using satellite lidar and ground-based Raman lidar measurements. A slight overestimation of the model-predicted volcanic ash number density was observed. Major requirements for future data assimilation of data from ACL have been identified, namely, the availability of calibrated lidar measurement data, a scattering database for atmospheric aerosols, a better representation and coverage of aerosols by the ash dispersion model, and more investigation in backscatter lidar forward operators which calculate the backscatter coefficient directly for each individual aerosol type. The introduced forward operator offers the flexibility to be adapted to a multitude of model systems and measurement setups.

  14. Airborne Sun Photometer Measurements of Aerosol Optical Depth during SOLVE II: Comparison with SAGE III and POAM III Measurements

    NASA Technical Reports Server (NTRS)

    Russell, P.; Livingston, J.; Schmid, B.; Eilers, J.; Kolyer, R.; Redemann, J.; Yee, J.-H.; Trepte, C.; Thomason, L.; Zawodny, J.

    2003-01-01

    The 14-channel NASA Ames Airborne Tracking Sunphotometer (AATS-14) was operated aboard the NASA DC-8 during the Second SAGE III Ozone Loss and Validation Experiment (SOLVE II) and obtained successful measurements during the sunlit segments of eight science flights. These included six flights out of Kiruna, Sweden, one flight out of NASA Dryden Flight Research Center (DFRC), and the Kiruna-DFRC return transit flight. Values of spectral aerosol optical depth (AOD), columnar ozone and columnar water vapor have been derived from the AATS-14 measurements. In this paper, we focus on AATS-14 AOD data. In particular, we compare AATS-14 AOD spectra with temporally and spatially near-coincident measurements by the Stratospheric Aerosol and Gas Experiment III (SAGE III) and the Polar Ozone and Aerosol Measurement III (POAM III) satellite sensors. We examine the effect on retrieved AOD of uncertainties in relative optical airmass (the ratio of AOD along the instrument-to-sun slant path to that along the vertical path) at large solar zenith angles. Airmass uncertainties result fiom uncertainties in requisite assumed vertical profiles of aerosol extinction due to inhomogeneity along the viewing path or simply to lack of available data. We also compare AATS-14 slant path solar transmission measurements with coincident measurements acquired from the DC-8 by the NASA Langley Research Center Gas and Aerosol Measurement Sensor (GAMS).

  15. Spatial and temporal variations of aerosols around Beijing in summer 2006: 2. Local and column aerosol optical properties

    NASA Astrophysics Data System (ADS)

    Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Fast, J. D.; PöSchl, U.; Garland, R. M.; Andreae, M. O.; Wiedensohler, A.; Sugimoto, N.; Zhu, T.

    2010-11-01

    Model calculations were conducted using the Weather Research and Forecasting model coupled with chemistry (WRF-chem) for the region around Beijing, China, in the summer of 2006, when the CAREBeijing-2006 intensive campaign was conducted. In this paper, we interpret aerosol optical properties in terms of aerosol mass concentrations and their chemical compositions by linking model calculations with measurements. The model calculations generally captured the observed variability of various surface and column aerosol optical parameters in and around Beijing. At the surface, the spatial and temporal variations of aerosol absorption and scattering coefficients corresponded well to those of elemental carbon and sulfate mass concentrations, respectively, and were controlled by local-scale (<100 km and <24 hours) and regional-scale (<500 km and <3 days) emissions, respectively. The contribution of secondary aerosols and their water uptake increased with altitude within the planetary boundary layer. This variation led to a considerable increase in column aerosol optical depth and was responsible for the differences in regional and temporal variations between surface and column aerosol optical properties around Beijing. These processes are expected to be common in other megacity regions as well. Model calculations, however, underestimated or overestimated the absolute levels of aerosol optical properties in and around Beijing by up to 60%. Sensitivity studies showed that these discrepancies were mostly due to the uncertainties in aerosol mixing state and aerosol density (affecting mass extinction efficiency) in the model calculations. Good agreement with measurements is achieved when these aerosol properties are accurately predicted or assumed; however, significant bias can result when these properties are inadequately treated, even if total aerosol mass concentrations are reproduced well in the model calculations.

  16. Overview of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Forcing on the Mediterranean Climate (ChArMEx/ADRIMED) summer 2013 campaign

    NASA Astrophysics Data System (ADS)

    Mallet, M.; Dulac, F.; Formenti, P.; Nabat, P.; Sciare, J.; Roberts, G.; Pelon, J.; Ancellet, G.; Tanré, D.; Parol, F.; Denjean, C.; Brogniez, G.; di Sarra, A.; Alados-Arboledas, L.; Arndt, J.; Auriol, F.; Blarel, L.; Bourrianne, T.; Chazette, P.; Chevaillier, S.; Claeys, M.; D'Anna, B.; Derimian, Y.; Desboeufs, K.; Di Iorio, T.; Doussin, J.-F.; Durand, P.; Féron, A.; Freney, E.; Gaimoz, C.; Goloub, P.; Gómez-Amo, J. L.; Granados-Muñoz, M. J.; Grand, N.; Hamonou, E.; Jankowiak, I.; Jeannot, M.; Léon, J.-F.; Maillé, M.; Mailler, S.; Meloni, D.; Menut, L.; Momboisse, G.; Nicolas, J.; Podvin, T.; Pont, V.; Rea, G.; Renard, J.-B.; Roblou, L.; Schepanski, K.; Schwarzenboeck, A.; Sellegri, K.; Sicard, M.; Solmon, F.; Somot, S.; Torres, B.; Totems, J.; Triquet, S.; Verdier, N.; Verwaerde, C.; Waquet, F.; Wenger, J.; Zapf, P.

    2016-01-01

    The Chemistry-Aerosol Mediterranean Experiment (ChArMEx; http://charmex.lsce.ipsl.fr) is a collaborative research program federating international activities to investigate Mediterranean regional chemistry-climate interactions. A special observing period (SOP-1a) including intensive airborne measurements was performed in the framework of the Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean region (ADRIMED) project during the Mediterranean dry season over the western and central Mediterranean basins, with a focus on aerosol-radiation measurements and their modeling. The SOP-1a took place from 11 June to 5 July 2013. Airborne measurements were made by both the ATR-42 and F-20 French research aircraft operated from Sardinia (Italy) and instrumented for in situ and remote-sensing measurements, respectively, and by sounding and drifting balloons, launched in Minorca. The experimental setup also involved several ground-based measurement sites on islands including two ground-based reference stations in Corsica and Lampedusa and secondary monitoring sites in Minorca and Sicily. Additional measurements including lidar profiling were also performed on alert during aircraft operations at EARLINET/ACTRIS stations at Granada and Barcelona in Spain, and in southern Italy. Remote-sensing aerosol products from satellites (MSG/SEVIRI, MODIS) and from the AERONET/PHOTONS network were also used. Dedicated meso-scale and regional modeling experiments were performed in relation to this observational effort. We provide here an overview of the different surface and aircraft observations deployed during the ChArMEx/ADRIMED period and of associated modeling studies together with an analysis of the synoptic conditions that determined the aerosol emission and transport. Meteorological conditions observed during this campaign (moderate temperatures and southern flows) were not favorable to producing high

  17. Biogenic VOC oxidation and organic aerosol formation in an urban nocturnal boundary layer: aircraft vertical profiles in Houston, TX

    NASA Astrophysics Data System (ADS)

    Brown, S. S.; Dubé, W. P.; Bahreini, R.; Middlebrook, A. M.; Brock, C. A.; Warneke, C.; de Gouw, J. A.; Washenfelder, R. A.; Atlas, E.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Schwarz, J. P.; Spackman, R.; Trainer, M.; Parrish, D. D.; Fehshenfeld, F. C.; Ravishankara, A. R.

    2013-05-01

    Organic compounds are a large component of aerosol mass, but organic aerosol (OA) sources remain poorly characterized. Recent model studies have suggested nighttime oxidation of biogenic hydrocarbons as a potentially large OA source, but analysis of field measurements to test these predictions is sparse. We present nighttime vertical profiles of nitrogen oxides, ozone, VOCs and aerosol composition measured during low approaches of the NOAA P-3 aircraft to airfields in Houston, TX. This region has large emissions of both biogenic hydrocarbons and nitrogen oxides. The latter serves as a source of the nitrate radical, NO3, a key nighttime oxidant. Biogenic VOCs (BVOC) and urban pollutants were concentrated within the nocturnal boundary layer (NBL), which varied in depth from 100-400 m. Despite concentrated NOx at low altitude, ozone was never titrated to zero, resulting in rapid NO3 radical production rates of 0.2-2.7ppbv h-1 within the NBL. Monoterpenes and isoprene were frequently present within the NBL and underwent rapid oxidation (up to 1ppbv h-1), mainly by NO3 and to a lesser extent O3. Concurrent enhancement in organic and nitrate aerosol on several profiles was consistent with primary emissions and with secondary production from nighttime BVOC oxidation, with the latter equivalent to or slightly larger than the former. Ratios of organic aerosol to CO within the NBL ranged from 14 to 38 μg m-3 OA/ppmv CO. A box model simulation incorporating monoterpene emissions, oxidant formation rates and monoterpene SOA yields suggested overnight OA production of 0.5 to 9 μg m-3.

  18. Measurements of Vertical Profiles of Turbulence, Temperature, Ozone, Aerosols, and BrO over Sea Ice and Tundra Snowpack during BROMEX

    NASA Astrophysics Data System (ADS)

    Shepson, P.; Caulton, D.; Cambaliza, M. L.; Dhaniyala, S.; Fuentes, J. D.; General, S.; Halfacre, J. W.; Nghiem, S. V.; Perez Perez, L.; Peterson, P. K.; Platt, U.; Pohler, D.; Pratt, K. A.; Simpson, W. R.; Stirm, B.; Walsh, S. J.; Zielcke, J.

    2012-12-01

    During the BROMEX field campaign of March 2012, we conducted measurements of boundary layer structure, ozone, BrO and aerosol, from a light, twin-engine aircraft during eleven flights originating from Barrow, AK. Flights were conducted over the sea ice in the Beaufort and Chukchi Seas, and over the tundra from Barrow to the Brooks Range, with vertical profiles covering altitudes from the surface to 3.5km in the free troposphere. Flights over the course of one month allowed a variety of sea ice conditions, including open water, nilas, first year sea ice, and frost flowers, to be examined over the Chukchi Sea. Atmospheric turbulence was measured using a calibrated turbulence probe, which will enable characterization of both the structure and turbulence of the Arctic boundary layer. Ozone was measured using a 2B UV absorption instrument. A GRIMM optical particle counter was used to measure 0.25-4 μm sized aerosol particles. The MAX-DOAS instrument enabled measurements of BrO vertical profiles. The aircraft measurements can be used to connect the surface measurements of ozone and BrO from the "Icelander" buoys, and the surface sites at Barrow, with those measured on the aircraft. Here we will discuss the spatial variability/coherence in these data. A major question that will be addressed using these data is the extent to which bromine is activated through reactions at the snowpack/ice surface versus the surface of aerosols. Here we will present a preliminary analysis of the relationships between snow/ice surface types, aerosol size-resolved number concentrations, and the vertical profiles of ozone and BrO.

  19. Causes of the great mass extinction of marine organisms in the Late Devonian

    NASA Astrophysics Data System (ADS)

    Barash, M. S.

    2016-11-01

    The second of the five great mass extinctions of the Phanerozoic occurred in the Late Devonian. The number of species decreased by 70-82%. Major crises occurred at the Frasnian-Famennian and Devonian-Carboniferous boundary. The lithological and geochemical compositions of sediments, volcanic deposits, impactites, carbon and oxygen isotope ratios, evidence of climate variability, and sea level changes reflect the processes that led the critical conditions. Critical intervals are marked by layers of black shales, which were deposited in euxinic or anoxic environments. These conditions were the main direct causes of the extinctions. The Late Devonian mass extinction was determined by a combination of impact events and extensive volcanism. They produced similar effects: emissions of harmful chemical compounds and aerosols to cause greenhouse warming; darkening of the atmosphere, which prevented photosynthesis; and stagnation of oceans and development of anoxia. Food chains collapsed and biological productivity decreased. As a result, all vital processes were disturbed and a large portion of the biota became extinct.

  20. Experimental Characterization of Radiation Forcing due to Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Sreenivas, K. R.; Singh, D. K.; Ponnulakshmi, V. K.; Subramanian, G.

    2011-11-01

    Micro-meteorological processes in the nocturnal atmospheric boundary layer (NBL) including the formation of radiation-fog and the development of inversion layers are controlled by heat transfer and the vertical temperature distribution close to the ground. In a recent study, it has been shown that the temperature profile close to the ground in stably-stratified, NBL is controlled by the radiative forcing due to suspended aerosols. Estimating aerosol forcing is also important in geo-engineering applications to evaluate the use of aerosols to mitigate greenhouse effects. Modeling capability in the above scenarios is limited by our knowledge of this forcing. Here, the design of an experimental setup is presented which can be used for evaluating the IR-radiation forcing on aerosols under either Rayleigh-Benard condition or under conditions corresponding to the NBL. We present results indicating the effect of surface emissivities of the top and bottom boundaries and the aerosol concentration on the temperature profiles. In order to understand the observed enhancement of the convection-threshold, we have determined the conduction-radiation time constant of an aerosol laden air layer. Our results help to explain observed temperature profiles in the NBL, the apparent stability of such profiles and indicate the need to account for the effect of aerosols in climatic/weather models.

  1. Profiling of Saharan dust from the Caribbean to western Africa - Part 2: Shipborne lidar measurements versus forecasts

    NASA Astrophysics Data System (ADS)

    Ansmann, Albert; Rittmeister, Franziska; Engelmann, Ronny; Basart, Sara; Jorba, Oriol; Spyrou, Christos; Remy, Samuel; Skupin, Annett; Baars, Holger; Seifert, Patric; Senf, Fabian; Kanitz, Thomas

    2017-12-01

    A unique 4-week ship cruise from Guadeloupe to Cabo Verde in April-May 2013 see part 1, Rittmeister et al. (2017) is used for an in-depth comparison of dust profiles observed with a polarization/Raman lidar aboard the German research vessel Meteor over the remote tropical Atlantic and respective dust forecasts of a regional (SKIRON) and two global atmospheric (dust) transport models (NMMB/BSC-Dust, MACC/CAMS). New options of model-observation comparisons are presented. We analyze how well the modeled fine dust (submicrometer particles) and coarse dust contributions to light extinction and mass concentration match respective lidar observations, and to what extent models, adjusted to aerosol optical thickness observations, are able to reproduce the observed layering and mixing of dust and non-dust (mostly marine) aerosol components over the remote tropical Atlantic. Based on the coherent set of dust profiles at well-defined distances from Africa (without any disturbance by anthropogenic aerosol sources over the ocean), we investigate how accurately the models handle dust removal at distances of 1500 km to more than 5000 km west of the Saharan dust source regions. It was found that (a) dust predictions are of acceptable quality for the first several days after dust emission up to 2000 km west of the African continent, (b) the removal of dust from the atmosphere is too strong for large transport paths in the global models, and (c) the simulated fine-to-coarse dust ratio (in terms of mass concentration and light extinction) is too high in the models compared to the observations. This deviation occurs initially close to the dust sources and then increases with distance from Africa and thus points to an overestimation of fine dust emission in the models.

  2. MODELING EXTRAGALACTIC EXTINCTION THROUGH GAMMA-RAY BURST AFTERGLOWS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zonca, Alberto; Mulas, Giacomo; Casu, Silvia

    We analyze extragalactic extinction profiles derived through gamma-ray burst afterglows, using a dust model specifically constructed on the assumption that dust grains are not immutable but respond, time-dependently, to the local physics. Such a model includes core-mantle spherical particles of mixed chemical composition (silicate core, sp{sup 2}, and sp{sup 3} carbonaceous layers), and an additional molecular component in the form of free-flying polycyclic aromatic hydrocarbons. We fit most of the observed extinction profiles. Failures occur for lines of sight, presenting remarkable rises blueward of the bump. We find a tendency for the carbon chemical structure to become more aliphatic withmore » the galactic activity, and to some extent with increasing redshifts. Moreover, the contribution of the molecular component to the total extinction is more important in younger objects. The results of the fitting procedure (either successes and failures) may be naturally interpreted through an evolutionary prescription based on the carbon cycle in the interstellar medium of galaxies.« less

  3. Patterns of generic extinction in the fossil record

    NASA Technical Reports Server (NTRS)

    Raup, D. M.; Boyajian, G. E.

    1988-01-01

    Analysis of the stratigraphic records of 19,897 fossil genera indicates that most classes and orders show largely congruent rises and falls in extinction intensity throughout the Phanerozoic. Even an ecologically homogeneous sample of reef genera shows the same basic extinction profile. The most likely explanation for the congruence is that extinction is physically rather than biologically driven and that it is dominated by the effects of geographically widespread environmental perturbations influencing most habitats. Significant departures from the congruence are uncommon but important because they indicate physiological or habitat selectivity. The similarity of the extinction records of reef organisms and the marine biota as a whole confirms that reefs and other faunas are responding to the same history of environmental stress.

  4. Calculation of color difference and measurement of the spectrum of aerosol based on human visual system

    NASA Astrophysics Data System (ADS)

    Dai, Mengyan; Liu, Jianghai; Cui, Jianlin; Chen, Chunsheng; Jia, Peng

    2017-10-01

    In order to solve the problem of the quantitative test of spectrum and color of aerosol, the measurement method of spectrum of aerosol based on human visual system was proposed. The spectrum characteristics and color parameters of three different aerosols were tested, and the color differences were calculated according to the CIE1976-L*a*b* color difference formula. Three tested powders (No 1# No 2# and No 3# ) were dispersed in a plexglass box and turned into aerosol. The powder sample was released by an injector with different dosages in each experiment. The spectrum and color of aerosol were measured by the PRO 6500 Fiber Optic Spectrometer. The experimental results showed that the extinction performance of aerosol became stronger and stronger with the increase of concentration of aerosol. While the chromaticity value differences of aerosols in the experiment were so small, luminance was verified to be the main influence factor of human eye visual perception and contributed most in the three factors of the color difference calculation. The extinction effect of No 3# aerosol was the strongest of all and caused the biggest change of luminance and color difference which would arouse the strongest human visual perception. According to the sensation level of chromatic color by Chinese, recognition color difference would be produced when the dosage of No 1# powder was more than 0.10 gram, the dosage of No 2# powder was more than 0.15 gram, and the dosage of No 3# powder was more than 0.05 gram.

  5. Stratospheric Aerosol and Gas Experiment (SAGE 3)

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.

    1993-01-01

    The proposed SAGE III instrument would be the principal source of data for global changes of stratospheric aerosols, stratospheric water vapor, and ozone profiles, and a contributing source of data for upper tropospheric water vapor, aerosols, and clouds. The ability to obtain such data has been demonstrated by the predecessor instrument, SAGE II, but SAGE III will be substantially more capable, as discussed below. The capabilities for monitoring the profiles of atmospheric constituents have been verified in detail, including ground-based validations, for aerosol, ozone, and water vapor. Indeed, because of its self-calibrating characteristics, SAGE II was an essential component of the international ozone trend assessments, and SAGE II is now proving to be invaluable in tracking the aerosols from Mt. Pinatubo. Although SAGE profiles generally terminate at the height of the first tropospheric cloud layer, it has been found that the measurements extend down to 3 km altitude more than 40 percent of the time at most latitudes. Thus, useful information can also be obtained on upper tropospheric aerosols, water vapor, and ozone.

  6. Evaluation of assumptions for estimating chemical light extinction at U.S. national parks.

    PubMed

    Lowenthal, Douglas; Zielinska, Barbara; Samburova, Vera; Collins, Don; Taylor, Nathan; Kumar, Naresh

    2015-03-01

    Studies were conducted at Great Smoky Mountains National Park (NP) (GRSM), Tennessee, Mount Rainier NP (MORA), Washington, and Acadia NP (ACAD), Maine, to evaluate assumptions used to estimate aerosol light extinction from chemical composition. The revised IMPROVE equation calculates light scattering from concentrations of PM2.5 sulfates, nitrates, organic carbon mass (OM), and soil. Organics are assumed to be nonhygroscopic. Organic carbon (OC) is converted to OM with a multiplier of 1.8. Experiments were conducted to evaluate assumptions on aerosol hydration state, the OM/OC ratio, OM hygroscopicity, and mass scattering efficiencies. Sulfates were neutralized by ammonium during winter at GRSM (W, winter) and at MORA during summer but were acidic at ACAD and GRSM (S, summer) during summer. Hygroscopic growth was mostly smooth and continuous, rarely exhibiting hysteresis. Deliquescence was not observed except infrequently during winter at GRSM (W). Water-soluble organic carbon (WSOC) was separated from bulk OC with solid-phase absorbents. The average OM/OC ratios were 2.0, 2.7, 2.1, and 2.2 at GRSM (S), GRSM (W), MORA, and ACAD, respectively. Hygroscopic growth factors (GF) at relative humidity (RH) 90% for aerosols generated from WSOC extracts averaged 1.19, 1.06, 1.13, and 1.16 at GRSM (S), GRSM (W), MORA, and ACAD, respectively. Thus, the assumption that OM is not hygroscopic may lead to underestimation of its contribution to light scattering. Studies at IMPROVE sites conducted in U.S. national parks showed that aerosol organics comprise more PM2.5 mass and absorb more water as a function of relative humidity than is currently assumed by the IMPROVE equation for calculating chemical light extinction. Future strategies for reducing regional haze may therefore need to focus more heavily on understanding the origins and control of anthropogenic sources of organic aerosols.

  7. Comparing Aerosol Retrievals from Ground-Based Instruments at the Impact-Pm Field Campaign

    NASA Astrophysics Data System (ADS)

    Kupinski, M.; Bradley, C. L.; Kalashnikova, O. V.; Xu, F.; Diner, D. J.; Clements, C. B.; Camacho, C.

    2016-12-01

    Detection of aerosol types, components having different size and chemical composition, over urban areas is important for understanding their impact on health and climate. In particular, sustained contact with size-differentiated airborne particulate matter: PM10 and PM2.5 can lead to adverse health effects such as asthma attacks, heart and lung diseases, and premature mortality. Multi-angular polarimetric measurements have been advocated in recent years as an additional tool to better understand and retrieve the aerosol properties needed for improved predictions of aerosol impart on air quality and climate. We deployed the ground-based Multiangle SpectroPolarimetric Imager (GroundMSPI) for accurate spectropolarimetric and radiance measurements co-located with the AERONET CIMEL sun photometer and a Halo Doppler 18 m resolution lidar from San José State University at the Garland-Fresno Air Quality supersite in Fresno, CA on July 7 during the Imaging Polarimetric Assessment and Characterization of Tropospheric Particulate Matter (ImPACT-PM) field experiment. GroundMSPI sampled the atmospheric scattering phase function in and 90 degrees out of the principal plane every 15 minutes in an automated manner, utilizing the 2-axis gimbal mount in elevation and azimuth. The goal of this work is verify atmospheric measurement of GroundMSPI with the coincident CIMEL sun photometer and ground-based lidar. Diffuse-sky radiance measurements of GroundMSPI are compared with the CIMEL sun photometer throughout the day. AERONET aerosol parameters such as size, shape, and index of refraction as well as lidar aerosol extinction profiles will be used in a forward radiative transfer model to compare with GroundMSPI observations and optimize these parameters to best match GroundMSPI data.

  8. Intercomparison of observations and model aerosol parameters during two Saharan dust events over the southern United Kingdom

    NASA Astrophysics Data System (ADS)

    Buxmann, Joelle; Adam, Mariana; Ordonez, Carlos; Tilbee, Marie; Smyth, Tim; Claxton, Bernard; Sugier, Jacqueline; Agnew, Paul

    2015-04-01

    Saharan desert dust lifted by convection over the hot desert surface can reach high altitudes and be transported over great distances. In the UK, Saharan dust episodes occur several times a year, usually during the spring. Dust lifted by cyclonic circulation is often blown into the Atlantic and transported to the UK. This can result in a rapid degradation of air quality due to the increase in the levels of particulate matter (PM). The ability to model the transport and deposition of dust remains an important challenge in order to characterize different pollution events. We present a comparison of observed Aerosol Optical Depth (AOD) with modelled AOD from the Met Office Air Quality Unified Model (AQUM), performed for two dust events in March 2014 (at 380nm, 440nm, 870nm and 1020nm). The observations are derived from five sun photometers located in the southern UK at Exeter, Cardington, Bayfordbury, Chilbolton, and Plymouth. Correlations are investigated between model column integrated PM2.5 and PM10, and observed fine and coarse mode AOD from AERONET. Vertical profiles of attenuated backscatter and extinction from the Jenoptik Nimbus ceilometers part of the Met Office Laser Cloud Base Recorder (LCBR) network are investigated as well (see also session AS3.17/GI2.2 Lidar and Applications). The Met Office air quality model AQUM is an on-line meteorology, chemistry and aerosol modelling system. It runs at a resolution of 12km over a domain covering the UK and north-western Europe. Atmospheric composition modelling employs two-way coupling between aerosol and chemistry evolution, with explicit modelling of sulphate, nitrate, black carbon, organic carbon, biomass burning and wind-blown mineral dust aerosol components. Both the model and observations show an increase in AOD during the first period from 12 -13 March 2014. For example AOD levels of up to 0.52 for the 380nm channel were recorded by the sun photometer in Exeter. This is relatively high compared to average

  9. Improving aerosol vertical retrieval for NWP application: Studying the impact of IR-sensed aerosol on data assimilation systems.

    NASA Astrophysics Data System (ADS)

    Oyola, Mayra; Marquis, Jared; Ruston, Benjamin; Campbell, James; Baker, Nancy; Westphal, Douglas; Zhang, Jianglong; Hyer, Edward

    2017-04-01

    Radiometric measurements from passive infrared (IR) sensors are important in numerical weather prediction (NWP) because they are sensitive to surface temperatures and atmospheric temperature profiles. However, these measurements are also sensitive to absorbing and scattering constituents in the atmosphere. Dust aerosols absorb in the IR and are found over many global regions with irregular spatial and temporal frequency. Retrievals of temperature using IR data are thus vulnerable to dust-IR radiance biases, most notably over tropical oceans where accurate surface and atmospheric temperatures are critical to accurate prediction of tropical cyclone development. Previous studies have shown that dust aerosols can bias retrieved brightness temperatures (BT) by up to 10K in some IR channels that are assimilated to constrain atmospheric temperature and water vapor profiles. Other BT-derived parameters such as sea surface temperatures (SSTs) are susceptible to negative biases of at least 1K or higher, which conflicts with the accuracy requirement for most research and operational applications (i.e., +/- 0.3 K). This problem is not limited to just satellite retrievals. BT bias also impacts the incorporation of background fields from NWP analyses in data assimilation (DA) systems. The effect of aerosols on IR fluxes at the ocean surface is a function of both aerosol loading and vertical profile. Therefore, knowledge of the aerosol vertical distribution, and understanding of how well this distribution is captured by NWP models, is necessary to ensuring proper treatment of aerosol-affected radiances in both retrieval and data assimilation. This understanding can be achieved by conducting modeling studies and by the exploitation of a robust observational dataset, such as satellite-based lidar profiling, which can be used to characterize aerosol type and distribution. In this talk, we describe such an application using the Navy Aerosol Analysis Prediction System (NAAPS) and

  10. Major Optical Depth Perturbations to the Stratosphere from Volcanic Eruptions: Stellar-Extinction Period, 1961-1978

    NASA Technical Reports Server (NTRS)

    Stothers, Richard B.; Hansen, James E. (Technical Monitor)

    2001-01-01

    A revised chronology of stratospheric aerosol extinction due to volcanic eruptions has been assembled for the period 1961-1978, which immediately precedes the era of dedicated satellite measurements. On the whole, the most accurate data consist of published observations of stellar extinction, supplemented in part by other kinds of observational data. The period covered encompasses the important eruptions of Agung (1963) and Fuego (1974), whose dust veils are discussed with respect to their transport, decay, and total mass. The effective (area-weighted mean) radii of the aerosols for both eruptions are found to be 0.3-0.4 microns. It is confirmed that, among known tropical eruptions, Agung's dust was unique for a low-latitude eruption in remaining almost entirely confined to the hemisphere of its production. A new table of homogeneous visual optical depth perturbations, listed by year and by hemisphere, is provided for the whole period 1881-1978, including the pyrheliometric period before 1961 that was investigated previously.

  11. Aerosol Sources, Absorption, and Intercontinental Transport: Synergies among Models, Remote Sensing, and Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Ginoux, Paul; Dubovik, Oleg; Holben, Brent; Kaufman, Yoram; chu, Allen; Anderson, Tad; Quinn, Patricia

    2003-01-01

    Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERONET at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

  12. Aerosol Sources, Absorption, and Intercontinental Transport: Synergies Among Models, Remote Sensing, and Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Chin, Mian; Chu, Allen; Levy, Robert; Remer, Lorraine; Kaufman, Yoram; Dubovik, Oleg; Holben, Brent; Eck, Tom; Anderson, Tad; Quinn, Patricia

    2004-01-01

    Aerosol climate forcing is one of the largest uncertainties in assessing the anthropogenic impact on the global climate system. This uncertainty arises from the poorly quantified aerosol sources, especially black carbon emissions, our limited knowledge of aerosol mixing state and optical properties, and the consequences of intercontinental transport of aerosols and their precursors. Here we use a global model GOCART to simulate atmospheric aerosols, including sulfate, black carbon, organic carbon, dust, and sea salt, from anthropogenic, .biomass burning, and natural sources. We compare the model calculated aerosol extinction and absorption with those quantities from the ground-based sun photometer measurements from AERON" at several different wavelengths and the field observations from ACE-Asia, and model calculated total aerosol optical depth and fine mode fractions with the MODIS satellite retrieval. We will also estimate the intercontinental transport of pollution and dust aerosols from their source regions to other areas in different seasons.

  13. The dependence of entrainment and drizzle in marine stratiform clouds on biomass burning aerosols derived from stable isotope and thermodynamic profiles

    NASA Astrophysics Data System (ADS)

    Henze, D.; Noone, D.

    2017-12-01

    A third of the world's biomass burning aerosol (BBA) particles are generated in southern Africa, and these particles are swept into the midlevel troposphere over the southeast Atlantic Ocean. The presence of these aerosols over the marine environment of the south east Atlantic offers a unique natural laboratory for studying aerosol effects on climate, and specifically a modification to the hydrologic cycle and microphysical characteristics of clouds. Different rates of condensation with high aerosol numbers change the precipitation rates in drizzling stratiform clouds, while the mixing of aerosols into the cloud layer is synonymous with entrainment from above cloud top near the top of the subtropical inversion. To better understanding the magnitude of the aerosol influence on southeast Atlantic boundary layer clouds we analyze the cloud-top entrainment and drizzle as a function of aerosol loading to determine the impact of BBA. Entrainment was determined from mixing line analysis based on profile measurements of moist static energy, total water, and the two most common heavy isotopes of water - HDO and H218O. Data was collected on the P-3 Orion aircraft during the NASA 2017 ORACLES campaign. Using these measurements, a box model was constructed using the combined conservation laws associated with all four of these quantities to estimate the entrainment and rainout of cloud liquid. The population of profiles sampled by the aircraft over the course of the 30 day mission spans varying concentrations of BBA. Initial plots of the water isotope mixing lines show where and to what degree the BBA air mass has mixed into the boundary layer air mass from above. This is demonstrated by the fact that the mixing end-members are the same for the different areas sampled, but the rate at which the various mixing lines are traversed as a function of altitude varies. Further, the mixing lines as a function of height traverse back and forth between end members multiple times over one

  14. Seasonal Differences in Tropical Western Pacific Cloud Ice, Water Vapor and Aerosols Observed From Space During ATTREX-III and POSIDON

    NASA Astrophysics Data System (ADS)

    Avery, M. A.; Rosenlof, K. H.; Vaughan, M.; Getzewich, B. J.; Thornberry, T. D.; Gao, R. S.; Rollins, A. W.; Woods, S.; Yorks, J. E.; Jensen, E. J.

    2017-12-01

    Recent aircraft missions sampling the tropical tropopause layer (TTL) in the tropical Western Pacific have provided a wealth of detailed cloud microphysical and associated aerosol, water vapor and temperature data for understanding processes that regulate stratospheric composition and hydration. This presentation seeks to provide a regional context for these measurements by comparing and contrasting active space-based observations from these time periods (Feb-Mar 2014 for ATTREX-III and Oct 2016 for POSIDON), primarily from the Clouds and Aerosol Lidar with Orthogonal Polarization (CALIOP), with the addition of Cloud Profiling Radar (CPR) and the Cloud-Aerosol Transport System (CATS) where these data sets are available. While the ATTREX III and POSIDON aircraft field missions both took place from Guam in the Western Pacific, there were striking differences between the amount, geographical distribution and properties of cirrus clouds and aerosols in the Tropical TTL. In addition to cloud and aerosol amount and location, we present geometric properties, including cloud top heights, transparent cloud and aerosol layer thicknesses and location of the 532 nm backscatter centroid, which is roughly equivalent to the layer vertical center of mass. We also present differences in the distribution of cirrus cloud extinction coefficients and ice water content, and aerosol optical depths, as detected from space, and compare these with in situ measurements and with temperature and water vapor distributions from the Microwave Limb Sounder (MLS). We find that there is more intense convection reaching the tropical tropopause during the POSIDON mission, and consequently more associated cloud ice observed during POSIDON than during ATTREX-III.

  15. Aerosol and ozone distributions over the western North Atlantic during WATOX-86

    NASA Astrophysics Data System (ADS)

    Bridgman, H. A.; Schnell, Russell C.; Bodhaine, B. A.; Oltmans, S. J.

    1988-03-01

    On January 4, 6, 8, and 9, 1986, a series of National Oceanic and Atmospheric Administration WP-3D research flights was conducted over the western Atlantic Ocean 200-300 km off the coast of North America from Nova Scotia to Georgia as part of the Western Atlantic Ocean Experiment (WATOX). Rights were made perpendicular to NW airflow to establish the flux of gas and aerosol emissions off the North American continent to the ocean. Representative condensation nucleus (CN) concentrations averaged 150-250 cm-3 in the free troposphere in clean conditions, but in atmospheric layers containing anthropogenic air pollution transported from long distances, CN concentrations reached 6500 cm-3. In the marine boundary layer, CN concentrations averaged 500 to 750 cm-3 under relatively clean conditions, and 1500 to 3000 cm-3 in polluted air. Aerosol scattering extinction (bsp) ranged from 70 × 10-6 m-1 in the marine boundary layer to 20 × 10-6 m-1 in the free troposphere. Aerosol bsp was not as responsive to changes in atmospheric structure as CN although factor-of-2 changes across the marine boundary layer were observed. Aerosol size spectra in the marine boundary layer were an order of magnitude greater than those in the free troposphere. Consistent peaks in the volume spectra between 8 and 10 μm diameter established the importance of sea salt as a major aerosol component. Ozone profiles in the free troposphere, normally in the 30-40 ppb range, exhibited laminae of enhanced concentrations (up to 70 ppb) at moisture boundaries, suggesting that active ozone production was occurring at these levels. Ozone concentrations within the marine boundary layer were generally lower than in the free troposphere.

  16. Impact of organic coating on growth of ammonium sulfate particles: light extinction measurements relevant for the direct effect

    NASA Astrophysics Data System (ADS)

    Robinson, C. B.; Zarzana, K. J.; Hasenkopf, C. A.; Tolbert, M. A.

    2012-12-01

    Light extinction by particles is strongly dependent on chemical composition, particle size, and water uptake. Relative humidity affects extinction by causing changes in refractive index and particle size due to hygroscopic growth. The ability of particles to take up water depends on their composition and structure. In both laboratory and field studies, inorganic salts completely covered by an organic coating have been observed. The impact of this coating on water uptake is uncertain, and a systematic study that examines water uptake as a function of relative humidity is highly desirable. These data are critical to evaluate the aerosol direct effect on climate, which is one of the most uncertain aspects of future climate change. In this study, we probe the connection between aerosol composition, size and light extinction directly by measuring fRHext, the ratio of the extinction coefficient for humidified particles to the extinction coefficient for dry particles. Particles were composed of 1,2,6-hexanetriol and ammonium sulfate, a system that forms organic coatings around the inorganic core. A cavity ring-down aerosol extinction spectrometer at 532 nm is used to measure the optical growth factor as a function of relative humidity. The fRHext values for a range of %RH for pure ammonium sulfate, pure 1,2,6-hexanetriol, and ammonium sulfate particles with 1,2,6-hexanetriol coatings were measured. The coated particles are created using a method of liquid-liquid separation, where the particles are exposed to water vapor creating a RH% above their deliquescence RH%. The particles are then dried with a Nafion dryer to a RH% that is below the point where liquid-liquid phase separation is observed, but above the efflorescence RH%. Pure 1,2,6-hexanetriol takes up little water over the observed RH range of 45-65%, and therefore fRHext ~ 1. With pure ammonium sulfate for the same RH% range, the fRHext varied from 1.5 - 2, depending on the RH% and the particle size. For the

  17. Spatial distribution of aerosol hygroscopicity and its effect on PM2.5 retrieval in East China

    NASA Astrophysics Data System (ADS)

    He, Qianshan; Zhou, Guangqiang; Geng, Fuhai; Gao, Wei; Yu, Wei

    2016-03-01

    The hygroscopic properties of aerosol particles have strong impact on climate as well as visibility in polluted areas. Understanding of the scattering enhancement due to water uptake is of great importance in linking dry aerosol measurements with relevant ambient measurements, especially for satellite retrievals. In this study, an observation-based algorithm combining meteorological data with the particulate matter (PM) measurement was introduced to estimate spatial distribution of indicators describing the integrated humidity effect in East China and the main factors impacting the hygroscopicity were explored. Investigation of 1 year data indicates that the larger mass extinction efficiency αext values (> 9.0 m2/g) located in middle and northern Jiangsu Province, which might be caused by particulate organic material (POM) and sulfate aerosol from industries and human activities. The high level of POM in Jiangsu Province might also be responsible for the lower growth coefficient γ value in this region. For the inland junction provinces of Jiangsu and Anhui, a considerable higher hygroscopic growth region in East China might be attributed to more hygroscopic particles mainly comprised of inorganic salts (e.g., sulfates and nitrates) from several large-scale industrial districts distributed in this region. Validation shows good agreement of calculated PM2.5 mass concentrations with in situ measurements in most stations with correlative coefficients of over 0.85, even if several defective stations induced by station location or seasonal variation of aerosol properties in this region. This algorithm can be used for more accurate surface level PM2.5 retrieval from satellite-based aerosol optical depth (AOD) with combination of the vertical correction for aerosol profile.

  18. Cloud Physics Lidar Optical Measurements During the SAFARI-2000 Field Campaign

    NASA Technical Reports Server (NTRS)

    Hlavka, Dennis L.; McGill, Matt; Hart, William D.; Spinhirne, James D.; Starr, David OC. (Technical Monitor)

    2002-01-01

    In this presentation, we will show new optical data processing results from the Cloud Physics War during SAFARI-2000. Retrieved products include aerosol and cloud layer location and identification, layer optical depths, vertical extinction profiles, and extinction-to-backscatter (S) ratios for 532 and 1064 nm. The retrievals will focus on the persistent and smoky planetary boundary layer and occasional elevated aerosol layers found in southern Africa during August and September 2000.

  19. Impact winter and the Cretaceous/Tertiary extinctions: Results of a Chicxulub asteroid impact model

    NASA Technical Reports Server (NTRS)

    Pope, Kevin O.; Baines, Kevin H.; Ocampo, Adriana C.; Ivanov, Boris A.

    1994-01-01

    The Chicxulub impact crater in Mexico is the site of the impact purported to have caused mass extinctions at the Cretaceous/Tertiary (K/T) boundary. 2-D hydrocode modeling of the impact, coupled with studies of the impact site geology, indiate that between 0.4 and 7.0 x 10(exp 17) g of sulfur were vaporized by the impact into anhydrite target rocks. A small portion of the sulfur was released as SO3 or SO4, which converted rapidly into H2SO4 aerosol and fell as acid rain. A radiative transfer model, coupled with a model of coagulation indicates that the aerosol prolonged the initial blackout period caused by impact dust only if the aerosol contained impurities. A larger portion of sulfur was released as SO2, which converted to aerosol slowly, due to the rate-limiting oxidation of SO2. Our radiative transfer calculations, combined with rates of acid production, coagulation, and diffusion indicate that solar transmission was reduced to 10-20% of normal for a period of 8-13 yr. This reduction produced a climate forcing (cooling) of -300 W/sq.m, which far exceeded the +8 W/sq.m greenhouse warming, caused by the CO2 released through the vaporization of carbonates, and therefore produced a decade of freezing and near-freezing temperatures. Several decades of moderate warming followed the decade of severe cooling due to the long residence time of CO2. The prolonged impact winter may have been a major cause of the K/T extinctions.

  20. Interpretation of DIAL Measurements of Lower Stratospheric Ozone in Regions with Pinatubo Aerosols

    NASA Technical Reports Server (NTRS)

    Grant, William B.; Browell, Edward V.; Fenn, Marta A.; Butler, Carolyn F.; Brackett, Vincent G.; Veiga, Robert E.; Mayor, Shane D.; Fishman, Jack; Nganga, D.; Minga, A.

    1992-01-01

    The influence of volcanic aerosols on stratospheric ozone is a topic of current interest, especially with the June 15, 1991 eruption of Mt. Pinatubo in the Philippines. Lidar has been used in the past to provide aerosol profiles which could be compared with ozone profiles measured using ozonesondes to look for coincidences between volcanic aerosols and ozone decreases. The differential absorption lidar (DIAL) technique has the advantages of being able to measure ozone and aerosol profiles simultaneously as well as being able to cover large geographical regions rapidly. While there are problems associated with correcting the ozone profiles for the presence of aerosols, the corrections can be made reliably when the wavelengths are closely spaced and the Bernoulli method is applied. The DIAL measurements considered in this paper are those obtained in the tropical stratosphere in January 1992 during the Airborne Arctic Stratospheric Expedition (AASE-II). The determination of ozone profiles in the presence of Pinatubo aerosols is discussed in a companion paper.

  1. Optical properties of aerosols at Grand Canyon National Park

    NASA Astrophysics Data System (ADS)

    Malm, William C.; Day, Derek E.

    Visibility in the United States is expected to improve over the next few decades because of reduced emissions, especially sulfur dioxide. In the eastern United States, sulfates make up about 60-70% of aerosol extinction, while in the inner mountain west that fraction is only about 30%. In the inner mountain west, carbon aerosols make up about 35% of extinction, while coarse mass contributes between 15 and 25% depending on how absorption is estimated. Although sulfur dioxide emissions are projected to decrease, carbon emissions due to prescribed fire activity will increase by factors of 5-10, and while optical properties of sulfates have been extensively studied, similar properties of carbon and coarse particles are less well understood. The inability to conclusively apportion about 50% of the extinction budget motivated a study to examine aerosol physio-chemical-optical properties at Grand Canyon, Arizona during the months of July and August. Coarse particle mass has usually been assumed to consist primarily of wind-blown dust, with a mass-scattering efficiency between about 0.4 and 0.6 m 2 g -1. Although there were episodes where crustal material made up most of the coarse mass, on the average, organics and crustal material mass were about equal. Furthermore, about one-half of the sampling periods had coarse-mass-scattering efficiencies greater than 0.6 m 2 g -1 and at times coarse-mass-scattering efficiencies were near 1.0 m 2 g -1. It was shown that absorption by coarse- and fine-particle absorption were about equal and that both fine organic and sulfate mass-scattering efficiencies were substantially less than the nominal values of 4.0 and 3.0 m 2 g -1 that have typically been used.

  2. Sensitivity of aerosol optical depth, single scattering albedo, and phase function calculations to assumptions on physical and chemical properties of aerosol

    EPA Science Inventory

    In coupled chemistry-meteorology simulations, the calculation of aerosol optical properties is an important task for the inclusion of the aerosol effects on the atmospheric radiative budget. However, the calculation of these properties from an aerosol profile is not uniquely defi...

  3. MODELING GALACTIC EXTINCTION WITH DUST AND 'REAL' POLYCYCLIC AROMATIC HYDROCARBONS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mulas, Giacomo; Casu, Silvia; Cecchi-Pestellini, Cesare

    We investigate the remarkable apparent variety of galactic extinction curves by modeling extinction profiles with core-mantle grains and a collection of single polycyclic aromatic hydrocarbons. Our aim is to translate a synthetic description of dust into physically well-grounded building blocks through the analysis of a statistically relevant sample of different extinction curves. All different flavors of observed extinction curves, ranging from the average galactic extinction curve to virtually 'bumpless' profiles, can be described by the present model. We prove that a mixture of a relatively small number (54 species in 4 charge states each) of polycyclic aromatic hydrocarbons can reproducemore » the features of the extinction curve in the ultraviolet, dismissing an old objection to the contribution of polycyclic aromatic hydrocarbons to the interstellar extinction curve. Despite the large number of free parameters (at most the 54 Multiplication-Sign 4 column densities of each species in each ionization state included in the molecular ensemble plus the 9 parameters defining the physical properties of classical particles), we can strongly constrain some physically relevant properties such as the total number of C atoms in all species and the mean charge of the mixture. Such properties are found to be largely independent of the adopted dust model whose variation provides effects that are orthogonal to those brought about by the molecular component. Finally, the fitting procedure, together with some physical sense, suggests (but does not require) the presence of an additional component of chemically different very small carbonaceous grains.« less

  4. Impact-driven ocean acidification as a mechanism of the Cretaceous-Palaeogene mass extinction

    NASA Astrophysics Data System (ADS)

    Ohno, S.; Kadono, T.; Kurosawa, K.; Hamura, T.; Sakaiya, T.; Shigemori, K.; Hironaka, Y.; Sano, T.; Watari, T.; Otani, K.; Matsui, T.; Sugita, S.

    2014-12-01

    The Cretaceous-Paleogene (K-Pg) mass extinction event at 66 Ma triggered by a meteorite impact is one of the most drastic events in the history of life on the Earth. Many hypotheses have been proposed as killing mechanisms induced by the impact, including global darkness due to high concentrations of atmospheric silicate dust particles, global wildfires, greenhouse warming due to CO2 release, and global acid rain. However, the actual mechanism of extinction remains highly controversial. One of the most important clues for understanding the extinction mechanism is the marine plankton record, which indicates that plankton foraminifera, living in the near-surface ocean, suffered very severe extinction in contrast to the high survival ratio of benthic foraminifera. No proposed extinction mechanism can account for this globally observed marine extinction pattern. Here, we show that SO3-rich impact vapor was released in the K-Pg impact and resulted in the occurrence of global acid rain and sudden severe ocean acidification at the end of the Cretaceous, based on the new results of impact experiments at velocities much higher than previous works (> 10 km/s) and theoretical calculations on aerosol coagulation processes. Sudden severe ocean acidification can account for many of the features of various geologic records at the K?Pg boundary, including severe extinction of plankton foraminifera. This extinction mechanism requires impact degassing of SO3-rich vapor, which is not necessarily found at impact sites other than Chicxulub, suggesting that the degree of mass extinction was controlled greatly by target lithology.

  5. The Impact of Aerosol Microphysical Representation in Models on the Direct Radiative Effect

    NASA Astrophysics Data System (ADS)

    Ridley, D. A.; Heald, C. L.

    2017-12-01

    Aerosol impacts the radiative balance of the atmosphere both directly and indirectly. There is considerable uncertainty remaining in the aerosol direct radiative effect (DRE), hampering understanding of the present magnitude of anthropogenic aerosol forcing and how future changes in aerosol loading will influence climate. Computationally expensive explicit aerosol microphysics are usually reserved for modelling of the aerosol indirect radiative effects that depend upon aerosol particle number. However, the direct radiative effects of aerosol are also strongly dependent upon the aerosol size distribution, especially particles between 0.2µm - 2µm diameter. In this work, we use a consistent model framework and consistent emissions to explore the impact of prescribed size distributions (bulk scheme) relative to explicit microphysics (sectional scheme) on the aerosol radiative properties. We consider the difference in aerosol burden, water uptake, and extinction efficiency resulting from the two representations, highlighting when and where the bulk and sectional schemes diverge significantly in their estimates of the DRE. Finally, we evaluate the modelled size distributions using in-situ measurements over a range of regimes to provide constraints on both the accumulation and coarse aerosol sizes.

  6. Aerosol particle size distribution in the stratosphere retrieved from SCIAMACHY limb measurements

    NASA Astrophysics Data System (ADS)

    Malinina, Elizaveta; Rozanov, Alexei; Rozanov, Vladimir; Liebing, Patricia; Bovensmann, Heinrich; Burrows, John P.

    2018-04-01

    aerosols in the Earth's atmosphere is of a great importance in the scientific community. While tropospheric aerosol influences the radiative balance of the troposphere and affects human health, stratospheric aerosol plays an important role in atmospheric chemistry and climate change. In particular, information about the amount and distribution of stratospheric aerosols is required to initialize climate models, as well as validate aerosol microphysics models and investigate geoengineering. In addition, good knowledge of stratospheric aerosol loading is needed to increase the retrieval accuracy of key trace gases (e.g. ozone or water vapour) when interpreting remote sensing measurements of the scattered solar light. The most commonly used characteristics to describe stratospheric aerosols are the aerosol extinction coefficient and Ångström coefficient. However, the use of particle size distribution parameters along with the aerosol number density is a more optimal approach. In this paper we present a new retrieval algorithm to obtain the particle size distribution of stratospheric aerosol from space-borne observations of the scattered solar light in the limb-viewing geometry. While the mode radius and width of the aerosol particle size distribution are retrieved, the aerosol particle number density profile remains unchanged. The latter is justified by a lower sensitivity of the limb-scattering measurements to changes in this parameter. To our knowledge this is the first data set providing two parameters of the particle size distribution of stratospheric aerosol from space-borne measurements of scattered solar light. Typically, the mode radius and w can be retrieved with an uncertainty of less than 20 %. The algorithm was successfully applied to the tropical region (20° N-20° S) for 10 years (2002-2012) of SCIAMACHY observations in limb-viewing geometry, establishing a unique data set. Analysis of this new climatology for the particle size

  7. Aerosol optical properties variability during biomass burning events observed by the eole-aias depolarization lidars over Athens, Greece (2007-2016)

    NASA Astrophysics Data System (ADS)

    Mylonaki, Maria; Papayannis, Alexandros; Mamouri, Rodanthi; Argyrouli, Athina; Kokkalis, Panagiotis; Tsaknakis, Georgios; Soupiona, Ourania

    2018-04-01

    The EOLE multi-wavelength aerosol Ramandepolarization lidar, and the AIAS depolarization lidar, in synergy with a sun photometer (CIMEL), were used, in the period 2007-2016, to provide the vertical profiles of the aerosol optical properties over Athens, Greece. More than 30 biomass burning events (fresh and aged smoke particles) were observed, with smoke layers between 1.5 up to 4-5 km height, while their duration ranged from 1-3 days. Lidar ratio (LR) values ranged from 40-105 sr (at 355 nm) and from 40-100 sr (at 532 nm), while the linear particle depolarization ratio (LPDR) at both 355 and 532 nm, remained <7%. The extinction-related Ångström exponent (AEa) at 355 nm/532 nm) ranged from 0.3 to 2.1. Additionally, a case of a near-range transport of biomass burning aerosols arriving over Athens up to 4 km height, between 27 and 28 June 2016, was studied. For this case, we found LRs of the order of 70±5 sr (355 nm) and 65±15 sr (532 nm) and AEa(355 nm/532 nm) around 1.

  8. The impact of aerosol vertical distribution on aerosol optical depth retrieval using CALIPSO and MODIS data: Case study over dust and smoke regions

    NASA Astrophysics Data System (ADS)

    Wu, Yerong; de Graaf, Martin; Menenti, Massimo

    2017-08-01

    Global quantitative aerosol information has been derived from MODerate Resolution Imaging SpectroRadiometer (MODIS) observations for decades since early 2000 and widely used for air quality and climate change research. However, the operational MODIS Aerosol Optical Depth (AOD) products Collection 6 (C6) can still be biased, because of uncertainty in assumed aerosol optical properties and aerosol vertical distribution. This study investigates the impact of aerosol vertical distribution on the AOD retrieval. We developed a new algorithm by considering dynamic vertical profiles, which is an adaptation of MODIS C6 Dark Target (C6_DT) algorithm over land. The new algorithm makes use of the aerosol vertical profile extracted from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements to generate an accurate top of the atmosphere (TOA) reflectance for the AOD retrieval, where the profile is assumed to be a single layer and represented as a Gaussian function with the mean height as single variable. To test the impact, a comparison was made between MODIS DT and Aerosol Robotic Network (AERONET) AOD, over dust and smoke regions. The results show that the aerosol vertical distribution has a strong impact on the AOD retrieval. The assumed aerosol layers close to the ground can negatively bias the retrievals in C6_DT. Regarding the evaluated smoke and dust layers, the new algorithm can improve the retrieval by reducing the negative biases by 3-5%.

  9. Optical-microphysical properties of Saharan dust aerosols and composition relationship using a multi-wavelength Raman lidar, in situ sensors and modelling: a case study analysis

    NASA Astrophysics Data System (ADS)

    Papayannis, A.; Mamouri, R. E.; Amiridis, V.; Remoundaki, E.; Tsaknakis, G.; Kokkalis, P.; Veselovskii, I.; Kolgotin, A.; Nenes, A.; Fountoukis, C.

    2012-05-01

    A strong Saharan dust event that occurred over the city of Athens, Greece (37.9° N, 23.6° E) between 27 March and 3 April 2009 was followed by a synergy of three instruments: a 6-wavelength Raman lidar, a CIMEL sun-sky radiometer and the MODIS sensor. The BSC-DREAM model was used to forecast the dust event and to simulate the vertical profiles of the aerosol concentration. Due to mixture of dust particles with low clouds during most of the reported period, the dust event could be followed by the lidar only during the cloud-free day of 2 April 2009. The lidar data obtained were used to retrieve the vertical profile of the optical (extinction and backscatter coefficients) properties of aerosols in the troposphere. The aerosol optical depth (AOD) values derived from the CIMEL ranged from 0.33-0.91 (355 nm) to 0.18-0.60 (532 nm), while the lidar ratio (LR) values retrieved from the Raman lidar ranged within 75-100 sr (355 nm) and 45-75 sr (532 nm). Inside a selected dust layer region, between 1.8 and 3.5 km height, mean LR values were 83 ± 7 and 54 ± 7 sr, at 355 and 532 nm, respectively, while the Ångström-backscatter-related (ABR355/532) and Ångström-extinction-related (AER355/532) were found larger than 1 (1.17 ± 0.08 and 1.11 ± 0.02, respectively), indicating mixing of dust with other particles. Additionally, a retrieval technique representing dust as a mixture of spheres and spheroids was used to derive the mean aerosol microphysical properties (mean and effective radius, number, surface and volume density, and mean refractive index) inside the selected atmospheric layers. Thus, the mean value of the retrieved refractive index was found to be 1.49( ± 0.10) + 0.007( ± 0.007)i, and that of the effective radiuses was 0.30 ± 0.18 μm. The final data set of the aerosol optical and microphysical properties along with the water vapor profiles obtained by Raman lidar were incorporated into the ISORROPIA II model to provide a possible aerosol composition

  10. Development, Comparisons and Evaluation of Aerosol Retrieval Algorithms

    NASA Astrophysics Data System (ADS)

    de Leeuw, G.; Holzer-Popp, T.; Aerosol-cci Team

    2011-12-01

    The Climate Change Initiative (cci) of the European Space Agency (ESA) has brought together a team of European Aerosol retrieval groups working on the development and improvement of aerosol retrieval algorithms. The goal of this cooperation is the development of methods to provide the best possible information on climate and climate change based on satellite observations. To achieve this, algorithms are characterized in detail as regards the retrieval approaches, the aerosol models used in each algorithm, cloud detection and surface treatment. A round-robin intercomparison of results from the various participating algorithms serves to identify the best modules or combinations of modules for each sensor. Annual global datasets including their uncertainties will then be produced and validated. The project builds on 9 existing algorithms to produce spectral aerosol optical depth (AOD and Ångström exponent) as well as other aerosol information; two instruments are included to provide the absorbing aerosol index (AAI) and stratospheric aerosol information. The algorithms included are: - 3 for ATSR (ORAC developed by RAL / Oxford university, ADV developed by FMI and the SU algorithm developed by Swansea University ) - 2 for MERIS (BAER by Bremen university and the ESA standard handled by HYGEOS) - 1 for POLDER over ocean (LOA) - 1 for synergetic retrieval (SYNAER by DLR ) - 1 for OMI retreival of the absorbing aerosol index with averaging kernel information (KNMI) - 1 for GOMOS stratospheric extinction profile retrieval (BIRA) The first seven algorithms aim at the retrieval of the AOD. However, each of the algorithms used differ in their approach, even for algorithms working with the same instrument such as ATSR or MERIS. To analyse the strengths and weaknesses of each algorithm several tests are made. The starting point for comparison and measurement of improvements is a retrieval run for 1 month, September 2008. The data from the same month are subsequently used for

  11. Regional characteristics of the relationship between columnar AOD and surface PM2.5: Application of lidar aerosol extinction profiles over Baltimore-Washington Corridor during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Chu, D. Allen; Ferrare, Richard; Szykman, James; Lewis, Jasper; Scarino, Amy; Hains, Jennifer; Burton, Sharon; Chen, Gao; Tsai, Tzuchin; Hostetler, Chris; Hair, Johnathan; Holben, Brent; Crawford, James

    2015-01-01

    The first field campaign of DISCOVER-AQ (Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality) took place in July 2011 over Baltimore-Washington Corridor (BWC). A suite of airborne remote sensing and in-situ sensors was deployed along with ground networks for mapping vertical and horizontal distribution of aerosols. Previous researches were based on a single lidar station because of the lack of regional coverage. This study uses the unique airborne HSRL (High Spectral Resolution Lidar) data to baseline PM2.5 (particulate matter of aerodynamic diameter less than 2.5 μm) estimates and applies to regional air quality with satellite AOD (Aerosol Optical Depth) retrievals over BWC (∼6500 km2). The linear approximation takes into account aerosols aloft above AML (Aerosol Mixing Layer) by normalizing AOD with haze layer height (i.e., AOD/HLH). The estimated PM2.5 mass concentrations by HSRL AOD/HLH are shown within 2 RMSE (Root Mean Square Error ∼9.6 μg/m3) with correlation ∼0.88 with the observed over BWC. Similar statistics are shown when applying HLH data from a single location over the distance of 100 km. In other words, a single lidar is feasible to cover the range of 100 km with expected uncertainties. The employment of MPLNET-AERONET (MicroPulse Lidar NETwork - AErosol RObotic NETwork) measurements at NASA GSFC produces similar statistics of PM2.5 estimates as those derived by HSRL. The synergy of active and passive remote sensing aerosol measurements provides the foundation for satellite application of air quality on a daily basis. For the optimal range of 10 km, the MODIS-estimated PM2.5 values are found satisfactory at 27 (out of 36) sunphotometer locations with mean RMSE of 1.6-3.3 μg/m3 relative to PM2.5 estimated by sunphotometers. The remaining 6 of 8 marginal sites are found in the coastal zone, for which associated large RMSE values ∼4.5-7.8 μg/m3 are most likely due to

  12. Extinction and anti-extinction: the "attentional waiting" hypothesis.

    PubMed

    Watling, Rosamond; Danckert, James; Linnell, Karina J; Cocchini, Gianna

    2013-03-01

    Patients with visual extinction have difficulty detecting a single contralesional stimulus when a second stimulus is simultaneously presented on the ipsilesional side. The rarely reported phenomenon of visual anti-extinction describes the opposite behavior, in which patients show greater difficulty in reporting a stimulus presented in isolation than they do in reporting 2 simultaneously presented stimuli. S. J. Goodrich and R. Ward (1997, Anti-extinction following unilateral parietal damage, Cognitive Neuropsychology, Vol. 14, pp. 595-612) suggested that visual anti-extinction is the result of a task-specific mechanism in which processing of the ipsilesional stimulus facilitates responses to the contralesional stimulus; in contrast, G. W. Humphreys, M. J. Riddoch, G. Nys, and D. Heinke (2002, Transient binding by time: Neuropsychological evidence from anti-extinction, Cognitive Neuropsychology, Vol. 19, pp. 361-380) suggested that temporal binding groups contralesional and ipsilesional stimuli together at brief exposure durations. We investigated extinction and anti-extinction phenomena in 3 brain-damaged patients using an extinction paradigm in which the stimulus exposure duration was systematically manipulated. Two patients showed both extinction and anti-extinction depending on the exposure duration of stimuli. Data confirmed the crucial role of duration in modulating the effect of extinction and anti-extinction. However, contrary to Humphreys and colleagues' (2002) single case, our patients showed extinction for short and anti-extinction for long exposure durations, suggesting that different mechanisms might underlie our patients' pattern of data. We discuss a novel "attentional waiting" hypothesis, which proposes that anti-extinction may be observed in patients showing extinction if the exposure duration of stimuli is increased. PsycINFO Database Record (c) 2013 APA, all rights reserved.

  13. High Altitude Emissions of Black Carbon Aerosols: Potential Climate Implications

    NASA Astrophysics Data System (ADS)

    Satheesh, S. K.

    2017-12-01

    Synthesizing a series of ground-based and airborne measurements of aerosols over the Indian region during summer and pre-monsoon seasons have revealed the persistence of elevated absorbing aerosol layers over most of the Indian region; more than 50% of which located above clouds. Subsequent, in situ measurements of black carbon (BC) using high-altitude balloons, showed surprising layers with high concentrations in the middle and upper troposphere even at an altitude of 8 to 10 kms. Simultaneous measurements of the vertical thermal structure have shown localized warming due to BC absorption leading to large reduction in lapse rate and sharp temperature inversion, which in turn increases the atmospheric stability. This aerosol-induced stable layer is conducive for maintaining the black carbon layer longer at that level, leading thereby to further solar absorption and subsequently triggering dry convection. These observations support the `solar escalator' concept through which absorption-warming-convection cycles lead to self-lifting of BC to upper troposphere or even to lower stratosphere under favorable conditions in a matter of a few days. Employing an on-line regional chemistry transport model (WRF-Chem), incorporating aircraft emissions, it is shown that emissions from high-flying aircrafts as the most likely source of these elevated black carbon layers. These in-situ injected particles, produce significant warming of the thin air in those heights and lift these layers to even upper tropospheric/lower stratospheric heights, aided by the strong monsoonal convection occurring over the region, which are known to overshoot the tropical tropopause leading to injection of tropospheric air mass (along with its constituent aerosols) into the stratosphere, especially during monsoon season when the tropical tropopause layer is known to be thinnest. These simulations are further supported by the CALIPSO space-borne LIDAR derived extinction coefficient profiles. Based on

  14. The influence of aerosols and land-use type on NO2 satellite retrieval over China

    NASA Astrophysics Data System (ADS)

    Liu, Mengyao; Lin, Jintai; Boersma, Folkert; Eskes, Henk; Chimot, Julien

    2017-04-01

    Both aerosols and surface reflectance have a strong influence on the retrieval of NO2 tropospheric vertical column densities (VCDs), especially over China with its heavy aerosol loading and rapid changes in land-use type. However, satellite retrievals of NO2 VCDs usually do not explicitly account for aerosol optical effects and surface reflectance anisotropy (BRDF) that varies in space and time. We develop an improved algorithm to derive tropospheric AMFs and VCDs over China from the OMI instrument - POMINO and DOMINO. This method can also be applied to TropOMI NO2 retrievals in the future. With small pixels of TropOMI and higher probability of encountering clear-sky scenes, the influence of BRDF and aerosol interference becomes more important than for OMI. Daily aerosol information is taken from the GEOS-Chem chemistry transport model and the aerosol optical depth (AOD) is adjusted via MODIS AOD climatology. We take the MODIS MCD43C2 C5 product to account for BRDF effects. The relative altitude of NO2 and aerosols is critical factor influencing the NO2 retrieval. In order to evaluate the aerosol extinction profiles (AEP) of GEOS-Chem improve our algorithm, we compare the GEOS-Chem simulation with CALIOP and develop a CALIOP AEP climatology to regulate the model's AEP. This provides a new way to include aerosol information into the tracer gas retrieval for OMI and TropOMI. Preliminary results indicate that the model performs reasonably well in reproducing the AEP shape. However, it seems to overestimate aerosols under 2km and underestimate above. We find that relative humidity (RH) is an important factor influencing the AEP shape when comparing the model with observations. If we adjust the GEOS-Chem RH to CALIOP's RH, the correlations of their AEPs also improve. Besides, take advantage of our retrieval method, we executed sensitivity tests to analyze their influences on NO2 trend and spatiotemporal variations in retrieval. It' the first time to investigate

  15. Lidar measurements of wildfire smoke aerosols in the atmosphere above Sofia, Bulgaria

    NASA Astrophysics Data System (ADS)

    Peshev, Zahary Y.; Deleva, Atanaska D.; Dreischuh, Tanja N.; Stoyanov, Dimitar V.

    2016-01-01

    Presented are results of lidar measurements and characterization of wildfire caused smoke aerosols observed in the atmosphere above the city of Sofia, Bulgaria, related to two local wildfires raging in forest areas near the city. A lidar systems based on a frequency-doubled Nd:YAG laser operated at 532 nm and 1064 nm is used in the smoke aerosol observations. It belongs to the Sofia LIDAR Station (at Laser Radars Laboratory, Institute of Electronics, Bulgarian Academy of Sciences), being a part of the European Aerosol Lidar Network. Optical, dynamical, microphysical, and geometrical properties and parameters of the observed smoke aerosol particles and layers are displayed and analyzed, such as: range/height-resolved profiles of the aerosol backscatter coefficient; integral aerosol backscattering; sets of colormaps displaying time series of the height distribution of the aerosol density; topologic, geometric, and volumetric properties of the smoke aerosol layers; time-averaged height profiles of backscatter-related Ångström exponent (BAE). Obtained results of retrieving and profiling smoke aerosols are commented in their relations to available meteorological and air-mass-transport forecasting and modelling data.

  16. Formation of Oxidized Organic Aerosol (OOA) through Fog Processing in the Po Valley

    NASA Astrophysics Data System (ADS)

    Gilardoni, S.; Paglione, M.; Rinaldi, M.; Giulianelli, L.; Massoli, P.; Hillamo, R. E.; Carbone, S.; Lanconelli, C.; Laaksonen, A. J.; Russell, L. M.; Poluzzi, V.; Fuzzi, S.; Facchini, C.

    2014-12-01

    Aqueous phase chemistry might be responsible for the formation of a significant fraction of the organic aerosol (OA) observed in the atmosphere, and could explain some of the discrepancies between OA concentration and properties predicted by models and observed in the environment. Aerosol - fog interaction and its effect on submicron aerosol properties were investigated in the Po Valley (northern Italy) during fall 2011, in the framework of the Supersite project (ARPA Emilia Romagna). Composition and physical properties of submicron aerosol were measured online by a High Resolution- Time of Flight - Aerosol Mass Spectrometer (HR-TOF-AMS), a Soot Photometer - Aerosol Mass Spectrometer (SP-AMS), and a Tandem Differential Mobility Particle Sizer (TDMPS). Organic functional group analysis was performed off-line by Hydrogen - Nuclear Magnetic Resonance (H-NMR) spectrometry and by Fourier Transform Infrared (FTIR) spectrometry. Aerosol absorption, scattering, and total extinction were measured simultaneously with a Particle Soot Absorption Photometer (PSAP), a Nephelometer, and a Cavity Attenuated Phase Shift Spectrometer particle extinction monitor (CAPS PMex), respectively. Water-soluble organic carbon in fog-water was characterized off-line by HR-TOF-AMS. Fourteen distinct fog events were observed. Fog dissipation left behind an aerosol enriched in particles larger than 400 nm, typical of fog and cloud processing, and dominated by secondary species, including ammonium nitrate, ammonium sulfate and oxidized OA (OOA). Source apportionment of OA allowed us to identify OOA as the difference between total OA and primary OA (hydrocarbon like OA and biomass burning OA). The formation of OOA through fog processing is proved by the correlation of OOA concentration with hydroxyl methyl sulfonate signal and by the similarity of OOA spectra with organic mass spectra obtained by re-aerosolization of fog water samples. The oxygen to carbon ratio and the hydrogen to carbon ratio of

  17. MULTIPLY: Development of a European HSRL Airborne Facility

    NASA Astrophysics Data System (ADS)

    Binietoglou, Ioannis; Serikov, Ilya; Nicolae, Doina; Amiridis, Vassillis; Belegante, Livio; Boscornea, Andrea; Brugmann, Bjorn; Costa Suros, Montserrat; Hellmann, David; Kokkalis, Panagiotis; Linne, Holger; Stachlewska, Iwona; Vajaiac, Sorin-Nicolae

    2016-08-01

    MULTIPLY is a novel airborne high spectral resolution lidar (HSRL) currently under development by a consortium of European institutions from Romania, Germany, Greece, and Poland. Its aim is to contribute to calibration and validations activities of the upcoming ESA aerosol sensing missions like ADM-Aeolus, EarthCARE and the Sentinel-3/-4/-5/-5p which include products related to atmospheric aerosols. The effectiveness of these missions depends on independent airborne measurements to develop and test the retrieval methods, and validate mission products following launch. The aim of ESA's MULTIPLY project is to design, develop, and test a multi-wavelength depolarization HSRL for airborne applications. The MULTIPLY lidar will deliver the aerosol extinction and backscatter coefficient profiles at three wavelengths (355nm, 532nm, 1064nm), as well as profiles of aerosol intensive parameters (Ångström exponents, extinction- to-backscatter ratios, and linear particle depolarization ratios).

  18. [Research on source profile of aerosol organic compounds in leather plant].

    PubMed

    Wang, Bo-Guang; Zhou, Yan; Feng, Zhi-Cheng; Liu, Hui-Xuan

    2009-04-15

    Through investigating current air pollution condition for PM10 in every factories of different style leather plants in Pearl River Delta, characteristic profile of semi-volatile organic compounds in PM10 emitted from leather factories and their contents were researched by using ultrasonic and gas chromatography and mass spectrum technology. The 6 types of organic compounds containing 46 species in total were found in the collected samples, including phenyl compounds, alcohols, PAHs, acids, esters and amides. The concentrations of PM10 in leather tanning plant, leather dying plant and man-made leather plant were 678.5, 454.5, 498.6 microgm x m(-3) respectively, and concentration of organic compounds in PM10 were 10.04, 6.89, 14.21 microg x m(-3) in sequence. The more important type of pollutants in each leather plants had higher contribution to total organic mass as follows, esters and amides in tanning plants profile account for 43.47% and 36.51% respectively; esters and alcohols in dying plants profiles account for 52.52% and 16.16% respectively; esters and amide in man-made leather plant have the highest content and account for 57.07% and 24.17% respectively. In the aerosol organic source profiles of tested leather plants, 9-octadecenamide was the abundant important species with the weight of 26.15% in tanning plant, and Bis(2-ethylhexyl) phthalate was up to 44.19% in the dying plant, and Bis(2-ethylhexyl) maleate and 1-hydroxy-piperidine had obviously higher weight in man-made plant than the other two plants.

  19. Boundary Layer Observations of Water Vapor and Aerosol Profiles with an Eye-Safe Micro-Pulse Differential Absorption Lidar (DIAL)

    NASA Astrophysics Data System (ADS)

    Nehrir, A. R.; Repasky, K. S.; Carlsten, J.; Ismail, S.

    2011-12-01

    Measurements of real-time high spatial and temporal resolution profiles of combined water vapor and aerosols in the boundary layer have been a long standing observational challenge to the meteorological, weather forecasting, and climate science communities. To overcome the high reoccurring costs associated with radiosondes as well as the lack of sufficient water vapor measurements over the continental united states, a compact and low cost eye-safe all semiconductor-based micro-pulse differential absorption lidar (DIAL) has been developed for water vapor and aerosol profiling in the lower troposphere. The laser transmitter utilizes two continuous wave external cavity diode lasers operating in the 830 nm absorption band as the online and offline seed laser sources. An optical switch is used to sequentially injection seed a tapered semiconductor optical amplifier (TSOA) with the two seed laser sources in a master oscillator power amplifier (MOPA) configuration. The TSOA is actively current pulsed to produce up to 7 μJ of output energy over a 1 μs pulse duration (150 m vertical resolution) at a 10 kHz pulse repetition frequency. The measured laser transmitter spectral linewidth is less than 500 kHz while the long term frequency stability of the stabilized on-line wavelength is ± 55 MHz. The laser transmitter spectral purity was measured to be greater than 0.9996, allowing for simultaneous measurements of water vapor in the lower and upper troposphere. The DIAL receiver utilizes a commercially available full sky-scanning capable 35 cm Schmidt-Cassegrain telescope to collect the scattered light from the laser transmitter. Light collected by the telescope is spectrally filtered to suppress background noise and is coupled into a fiber optic cable which acts as the system field stop and limits the full angle field of view to 140 μrad. The light is sampled by a fiber coupled APD operated in a Geiger mode. The DIAL instrument is operated autonomously where water vapor and

  20. Aerosol Lidar and MODIS Satellite Comparisons for Future Aerosol Loading Forecast

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

    2006-01-01

    Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

  1. Vertical variability of aerosol single-scattering albedo and equivalent black carbon concentration based on in-situ and remote sensing techniques during the iAREA campaigns in Ny-Ålesund

    NASA Astrophysics Data System (ADS)

    Markowicz, K. M.; Ritter, C.; Lisok, J.; Makuch, P.; Stachlewska, I. S.; Cappelletti, D.; Mazzola, M.; Chilinski, M. T.

    2017-09-01

    This work presents a methodology for obtaining vertical profiles of aerosol single scattering properties based on a combination of different measurement techniques. The presented data were obtained under the iAREA (Impact of absorbing aerosols on radiative forcing in the European Arctic) campaigns conducted in Ny-Ålesund (Spitsbergen) during the spring seasons of 2015-2017. The retrieval uses in-situ observations of black carbon concentration and absorption coefficient measured by a micro-aethalometer AE-51 mounted onboard a tethered balloon, as well as remote sensing data obtained from sun photometer and lidar measurements. From a combination of the balloon-borne in-situ and the lidar data, we derived profiles of single scattering albedo (SSA) as well as absorption, extinction, and aerosol number concentration. Results have been obtained in an altitude range from about 400 m up to 1600 m a.s.l. and for cases with increased aerosol load during the Arctic haze seasons of 2015 and 2016. The main results consist of the observation of increasing values of equivalent black carbon (EBC) and absorption coefficient with altitude, and the opposite trend for aerosol concentration for particles larger than 0.3 μm. SSA was retrieved with the use of lidar Raman and Klett algorithms for both 532 and 880 nm wavelengths. In most profiles, SSA shows relatively high temporal and altitude variability. Vertical variability of SSA computed from both methods is consistent; however, some discrepancy is related to Raman retrieval uncertainty and absorption coefficient estimation from AE-51. Typically, very low EBC concentration in Ny-Ålesund leads to large error in the absorbing coefficient. However, SSA uncertainty for both Raman and Klett algorithms seems to be reasonable, e.g. SSA of 0.98 and 0.95 relate to an error of ±0.01 and ± 0.025, respectively.

  2. Impact of Aerosols on Atmospheric Attenuation Loss in Central Receiver Systems: Preprint

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sengupta, M.; Wagner, M. J.

    2011-08-01

    Atmospheric attenuation loss between the heliostat field and receiver has been recognized as a significant source of loss in Central Receiver Systems. In clear sky situations, extinction of Direct Normal Irradiance (DNI) is primarily by aerosols in the atmosphere. When aerosol loading is high close to the surface the attenuation loss between heliostat and receivers is significantly influenced by the amount of aerosols present on a particular day. This study relates measured DNI to aerosol optical depths close to the surface of the earth. The model developed in the paper uses only measured DNI to estimate the attenuation between heliostatmore » and receiver in a central receiver system. The requirement that only a DNI measurement is available potentially makes the model a candidate for widespread use.« less

  3. SAGE 1 data user's guide

    NASA Technical Reports Server (NTRS)

    Mcmaster, Leonard R.; Chu, William P.; Rowland, Michael W.

    1992-01-01

    A guide for using the data products from the Stratospheric Aerosol and Gas Experiment 1 (SAGE 1) for scientific investigations of stratospheric chemistry related to aerosol, ozone, nitrogen dioxide, dynamics, and climate change is presented. A detailed description of the aerosol profile tape, the ozone profile tape, and the nitrogen dioxide profile tape is included. These tapes are the SAGE 1 data products containing aerosol extinction data and ozone and nitrogen dioxide concentration data for use in the different scientific investigations. Brief descriptions of the instrument operation, data collection, processing, and validation, and some of the scientific analyses that were conducted are also included.

  4. Aerosol and cloud properties derived from hyperspectral transmitted light in the southeast Atlantic sampled during field campaign deployments in 2016 and 2017

    NASA Astrophysics Data System (ADS)

    LeBlanc, S. E.; Redemann, J.; Flynn, C. J.; Segal-Rosenhaimer, M.; Kacenelenbogen, M. S.; Shinozuka, Y.; Pistone, K.; Karol, Y.; Schmidt, S.; Cochrane, S.; Chen, H.; Meyer, K.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.

    2017-12-01

    We present aerosol and cloud properties collected from airborne remote-sensing measurements in the southeast Atlantic during the recent NASA ObseRvations of CLouds above Aerosols and their intEractionS (ORACLES) field campaign. During the biomass burning seasons of September 2016 and August 2017, we sampled aerosol layers which overlaid marine stratocumulus clouds off the southwestern coast of Africa. We sampled these aerosol layers and the underlying clouds from the NASA P3 airborne platform with the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research (4STAR). Aerosol optical depth (AOD), along with trace gas content in the atmospheric column (water vapor, NO2, and O3), is obtained from the attenuation in the sun's direct beam, measured at the altitude of the airborne platform. Using hyperspectral transmitted light measurements from 4STAR, in conjunction with hyperspectral hemispheric irradiance measurements from the Solar Spectral Flux Radiometers (SSFR), we also obtained aerosol intensive properties (asymmetry parameter, single scattering albedo), aerosol size distributions, cloud optical depth (COD), cloud particle effective radius, and cloud thermodynamic phase. Aerosol intensive properties are retrieved from measurements of angularly resolved skylight and flight level spectral albedo using the inversion used with measurements from AERONET (Aerosol Robotic Network) that has been modified for airborne use. The cloud properties are obtained from 4STAR measurements of scattered light below clouds. We show a favorable initial comparison of the above-cloud AOD measured by 4STAR to this same product retrieved from measurements by the MODIS instrument on board the TERRA and AQUA satellites. The layer AOD observed above clouds will also be compared to integrated aerosol extinction profile measurements from the High Spectral Resolution Lidar-2 (HSRL-2).

  5. Evolution of aerosol vertical distribution during particulate pollution events in Shanghai

    NASA Astrophysics Data System (ADS)

    Zhang, Yunwei; Zhang, Qun; Leng, Chunpeng; Zhang, Deqin; Cheng, Tiantao; Tao, Jun; Zhang, Renjian; He, Qianshan

    2015-06-01

    A set of micro pulse lidar (MPL) systems operating at 532 nm was used for ground-based observation of aerosols in Shanghai in 2011. Three typical particulate pollution events (e.g., haze) were examined to determine the evolution of aerosol vertical distribution and the planetary boundary layer (PBL) during these pollution episodes. The aerosol vertical extinction coefficient (VEC) at any given measured altitude was prominently larger during haze periods than that before or after the associated event. Aerosols originating from various source regions exerted forcing to some extent on aerosol loading and vertical layering, leading to different aerosol vertical distribution structures. Aerosol VECs were always maximized near the surface owing to the potential influence of local pollutant emissions. Several peaks in aerosol VECs were found at altitudes above 1 km during the dust- and bioburning-influenced haze events. Aerosol VECs decreased with increasing altitude during the local-polluted haze event, with a single maximum in the surface atmosphere. PM2.5 increased slowly while PBL and visibility decreased gradually in the early stages of haze events; subsequently, PM2.5 accumulated and was exacerbated until serious pollution bursts occurred in the middle and later stages. The results reveal that aerosols from different sources impact aerosol vertical distributions in the atmosphere and that the relationship between PBL and pollutant loadings may play an important role in the formation of pollution.

  6. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already

  7. The post-pinatubo evolution of stratospheric aerosol surface area density as inferred from SAGE 2

    NASA Technical Reports Server (NTRS)

    Poole, L. R.; Thomason, L. W.

    1994-01-01

    Following the eruption of Mount Pinatubo in June of 1991, the aerosol mass loading of the stratosphere increased from -1 Mt to approximately 30 Mt. This change in aerosol loading was responsible for numerous radiative and chemical changes observed within the stratosphere. As a result, the ability to quantify aerosol properties on a global basis during this period is important. Aerosol surface area density is a critical parameter in governing the rates of heterogeneous reactions, such as ClONO2 plus H2O yields HNO3 plus HOCl, which influence the stratospheric abundance of ozone. Following the eruption of Mt. Pinatubo, measurements by the Stratospheric Aerosol and Gas Experiment (SAGE 2) indicated that the stratospheric aerosol surface area density increased by as much as a factor of 100. Using SAGE 2 multi-wavelength aerosol extinction data, aerosol surface area density as well as mass are derived for the period following the eruption of Mt. Pinatubo through the present.

  8. Dual-wavelength dual-cavity spectrometer for NO2 detection in the presence of aerosol interference

    NASA Astrophysics Data System (ADS)

    Chandran, Satheesh; Puthukkudy, Anin; Varma, Ravi

    2017-07-01

    Precise determination of concentration of gases, such as NO2, in urban atmosphere is crucial in studying chemical reactions leading to secondary pollutants. In this study, a novel and sensitive yet simple and cost effective spectrometer was developed where two laser wavelengths and two parallel identical optical cavities were used. Monitoring of NO2 even in the presence of aerosol spectral interference was demonstrated. The intensity transmitted through one cavity, evacuated to 0.1 mbar, was designated as the reference signal ( I 0) while that through the other cavity, sampling air at atmospheric pressure, was designated as sample signal ( I). Quasi-simultaneous measurements of these I 0 and I were done for both laser wavelengths sequentially: one at 406.4 nm near the peak of the largest electronic transition of NO2 and the other at 446.9 nm, away from the peak yet exhibiting significant absorption. The addition of the second wavelength where NO2 has absorption was to ascertain the presence of aerosol scattering and compensate for it. Aerosol extinctions at both operating wavelengths were assumed to be the same, their ratio taken as unity for simplicity, and aerosol light extinction was retrieved. The spectrometer with average sampling interval of 5 s exhibited detection sensitivity of low parts per billion concentrations.

  9. Aerosol Classification from High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Hair, J. W.; Ferrare, R. A.; Hostetler, C. A.; Kahnert, M.; Vaughan, M. A.; Cook, A. L.; Harper, D. B.; Berkoff, T.; Seaman, S. T.; Collins, J. E., Jr.; Fenn, M. A.; Rogers, R. R.

    2015-12-01

    The NASA Langley airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, have acquired large datasets of vertically resolved aerosol extinction, backscatter, and depolarization during >30 airborne field missions since 2006. The lidar measurements of aerosol intensive parameters like lidar ratio and color ratio embed information about intrinsic aerosol properties, and are combined to qualitatively classify HSRL aerosol measurements into aerosol types. Knowledge of aerosol type is important for assessing aerosol radiative forcing, and can provide useful information for source attribution studies. However, atmospheric aerosol is frequently not a single pure type, but instead is a mixture, which affects the optical and radiative properties of the aerosol. We show that aerosol intensive parameters measured by lidar can be understood using mixing rules for cases of external mixing. Beyond coarse classification and mixing between classes, variations in the lidar aerosol intensive parameters provide additional insight into aerosol processes and composition. This is illustrated by depolarization measurements at three wavelengths, 355 nm, 532 nm, and 1064 nm, made by HSRL-2. Particle depolarization ratio is an indicator of non-spherical particles. Three cases each have a significantly different spectral dependence of the depolarization ratio, related to the size of the depolarizing particles. For two dust cases, large non-spherical particles account for the depolarization of the lidar light. The spectral dependence reflects the size distribution of these particles and reveals differences in the transport histories of the two plumes. For a smoke case, the depolarization is inferred to be due to the presence of small coated soot aggregates. Interestingly, the depolarization at 355 nm is similar for this smoke case compared to the dust cases, having potential implications for the upcoming EarthCARE satellite, which will measure particle depolarization ratio only at 355 nm.

  10. Sun and aureole spectrometer for airborne measurements to derive aerosol optical properties.

    PubMed

    Asseng, Hagen; Ruhtz, Thomas; Fischer, Jürgen

    2004-04-01

    We have designed an airborne spectrometer system for the simultaneous measurement of the direct Sun irradiance and aureole radiance. The instrument is based on diffraction grating spectrometers with linear image sensors. It is robust, lightweight, compact, and reliable, characteristics that are important for airborne applications. The multispectral radiation measurements are used to derive optical properties of tropospheric aerosols. We extract the altitude dependence of the aerosol volume scattering function and of the aerosol optical depth by using flight patterns with descents and ascents ranging from the surface level to the top of the boundary layer. The extinction coefficient and the product of single scattering albedo and phase function of separate layers can be derived from the airborne measurements.

  11. Continuous Water Vapor Profiles from Operational Ground-Based Active and Passive Remote Sensors

    NASA Technical Reports Server (NTRS)

    Turner, D. D.; Feltz, W. F.; Ferrare, R. A.

    2000-01-01

    The Atmospheric Radiation Measurement program's Southern Great Plains Cloud and Radiation Testbed site central facility near Lamont, Oklahoma, offers unique operational water vapor profiling capabilities, including active and passive remote sensors as well as traditional in situ radiosonde measurements. Remote sensing technologies include an automated Raman lidar and an automated Atmospheric Emitted Radiance Interferometer (AERI), which are able to retrieve water vapor profiles operationally through the lower troposphere throughout the diurnal cycle. Comparisons of these two water vapor remote sensing methods to each other and to radiosondes over an 8-month period are presented and discussed, highlighting the accuracy and limitations of each method. Additionally, the AERI is able to retrieve profiles of temperature while the Raman lidar is able to retrieve aerosol extinction profiles operationally. These data, coupled with hourly wind profiles from a 915-MHz wind profiler, provide complete specification of the state of the atmosphere in noncloudy skies. Several case studies illustrate the utility of these high temporal resolution measurements in the characterization of mesoscale features within a 3-day time period in which passage of a dryline, warm air advection, and cold front occurred.

  12. Aerosol in the Upper Troposphere Lower Stratosphere, decadal Simulations of Radiative Forcing using the Chemistry Circulation Model EMAC and MIPAS, GOMOS, IASI and other Satellite Data

    NASA Astrophysics Data System (ADS)

    Bruehl, C.; Schallock, J.; Lelieveld, J.; Bingen, C.; Robert, C. E.; Hoepfner, M.; Clarisse, L.

    2017-12-01

    The atmospheric chemistry - general circulation model EMAC with a modal interactive aerosol module is used to estimate radiative effects of UTLS aerosol for the ENVISAT period 2002 to 2012 in the framework of SPARC/SSIRC. Volcanic SO2 injections by about 230 explosive volcano eruptions are estimated mostly from MIPAS limb observations. For periods of data gaps, injected SO2 is estimated indirectly from extinctions observed by GOMOS. GOMOS extinctions in the UTLS and the seasonal component of radiative forcing can be only reproduced by the model if a comprehensive treatment of desert dust and organic and black carbon is included. Upward transport of particles and gases by the Asian Monsoon appears to contribute importantly. The time series of simulated stratospheric aerosol optical depth and radiative forcing agree with the corresponding quantities derived from different satellite data sets. Comparisons of total aerosol optical depth with IASI show that tropospheric and stratospheric aerosol in the model are consistently and realistically represented.

  13. CATS Aerosol Typing and Future Directions

    NASA Technical Reports Server (NTRS)

    McGill, Matt; Yorks, John; Scott, Stan; Palm, Stephen; Hlavka, Dennis; Hart, William; Nowottnick, Ed; Selmer, Patrick; Kupchock, Andrew; Midzak, Natalie; hide

    2016-01-01

    The Cloud Aerosol Transport System (CATS), launched in January of 2015, is a lidar remote sensing instrument that will provide range-resolved profile measurements of atmospheric aerosols and clouds from the International Space Station (ISS). CATS is intended to operate on-orbit for at least six months, and up to three years. Status of CATS Level 2 and Plans for the Future:Version. 1. Aerosol Typing (ongoing): Mode 1: L1B data released later this summer; L2 data released shortly after; Identify algorithm biases (ex. striping, FOV (field of view) biases). Mode 2: Processed Released Currently working on correcting algorithm issues. Version 2 Aerosol Typing (Fall, 2016): Implementation of version 1 modifications Integrate GEOS-5 aerosols for typing guidance for non spherical aerosols. Version 3 Aerosol Typing (2017): Implementation of 1-D Var Assimilation into GEOS-5 Dynamic lidar ratio that will evolve in conjunction with simulated aerosol mixtures.

  14. Airborne Sunphotometer Studies of Aerosol Properties and Effects, Including Closure Among Satellite, Suborbital Remote, and In situ Measurements

    NASA Technical Reports Server (NTRS)

    Russlee, Philip B.; Schmid, B.; Redemann, J.; Livingston, J. M.; Bergstrom, R. W.; Ramirez, S. A.; Hipskind, R. Stephen (Technical Monitor)

    2001-01-01

    Airborne sunphotometry has been used to measure aerosols from North America, Europe, and Africa in coordination with satellite and in situ measurements in TARFOX (1996), ACE-2 (1997), PRIDE (2000), and SAFARI 2000. Similar coordinated measurements of Asian aerosols are being conducted this spring in ACE-Asia and are planned for North American aerosols this summer in CLAMS. This paper summarizes the approaches used, key results, and implications for aerosol properties and effects, such as single scattering albedo and regional radiative forcing. The approaches exploit the three-dimensional mobility of airborne sunphotometry to access satellite scenes over diverse surfaces (including open ocean with and without sunglint) and to match exactly the atmospheric layers sampled by airborne in situ measurements and other radiometers. These measurements permit tests of the consistency, or closure, among such diverse measurements as aerosol size-resolved chemical composition; number or mass concentration; light extinction, absorption, and scattering (total, hemispheric back and 180 deg.); and radiative fluxes. In this way the airborne sunphotometer measurements provide a key link between satellite and in situ measurements that helps to understand any discrepancies that are found. These comparisons have led to several characteristic results. Typically these include: (1) Better agreement among different types of remote measurements than between remote and in situ measurements. (2) More extinction derived from transmission measurements than from in situ measurements. (3) Larger aerosol absorption inferred from flux radiometry than from in situ measurements. Aerosol intensive properties derived from these closure studies have been combined with satellite-retrieved fields of optical depth to produce fields of regional radiative forcing. We show results for the North Atlantic derived from AVHRR optical depths and aerosol intensive properties from TARFOX and ACE-2. Companion papers

  15. Near-IR extinction and backscatter coefficient measurements in low- and mid-altitude clouds

    NASA Technical Reports Server (NTRS)

    Sztankay, Z. G.

    1986-01-01

    Knowledge of the attenuation and backscattering properties of clouds is required to high resolution for several types of optical sensing systems. Such data was obtained in about 15 hours of flights through clouds in the vicinity of Washington, D.C. The flights were mainly through stratocumulus, altocumulus, stratus, and stratus fractus clouds and covered an altitude and temperature range of 300 to 3200 m and -13 to 17 C. Two instruments were flown, each of which measured the backscatter from close range in two range bins to independently determine both the extinction and backscatter coefficients. The extinction and backscatter coefficients can be obtained from the signals in the two channels of each instrument, provided that the aerosol is uniform over the measurement region. When this assumptions holds, the extinction coefficient is derived basically from the ratio of the signal in the two channels; the backscatter coefficient can then be obtained from the signal in either channel.

  16. Automated retrieval of cloud and aerosol properties from the ARM Raman lidar, part 1: feature detection

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Thorsen, Tyler J.; Fu, Qiang; Newsom, Rob K.

    A Feature detection and EXtinction retrieval (FEX) algorithm for the Atmospheric Radiation Measurement (ARM) program’s Raman lidar (RL) has been developed. Presented here is part 1 of the FEX algorithm: the detection of features including both clouds and aerosols. The approach of FEX is to use multiple quantities— scattering ratios derived using elastic and nitro-gen channel signals from two fields of view, the scattering ratio derived using only the elastic channel, and the total volume depolarization ratio— to identify features using range-dependent detection thresholds. FEX is designed to be context-sensitive with thresholds determined for each profile by calculating the expectedmore » clear-sky signal and noise. The use of multiple quantities pro-vides complementary depictions of cloud and aerosol locations and allows for consistency checks to improve the accuracy of the feature mask. The depolarization ratio is shown to be particularly effective at detecting optically-thin features containing non-spherical particles such as cirrus clouds. Improve-ments over the existing ARM RL cloud mask are shown. The performance of FEX is validated against a collocated micropulse lidar and observations from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite over the ARM Darwin, Australia site. While we focus on a specific lidar system, the FEX framework presented here is suitable for other Raman or high spectral resolution lidars.« less

  17. Trace Gases and Aerosols Simulated Over the Indian Domain: Evaluation of the Model Wrf-Chem

    NASA Astrophysics Data System (ADS)

    Michael, M.; Yadav, A.; Tripathi, S. N.; Venkataraman, C.; Kanawade, V. P.

    2012-12-01

    As the anthropogenic emissions from the Asian countries contribute substantially to the global aerosol loading, the study of the distribution of trace gases and aerosols over this region has received increasing attention in recent years. In the present work, the aerosol properties over the Indian domain during the pre-monsoon season has been addressed. The "online" meteorological and chemical transport Weather Research and Forecasting-Chemistry (WRF-Chem) model has been implemented over Indian subcontinent for three consecutive summers in 2008, 2009 and 2010.The initial and boundary conditions are obtained from NCAR reanalysis data. The global emission inventories (REanalysis of the TROpospheric chemical composition (RETRO) and Emissions Database for Global Atmospheric Research (EDGAR)) have been used and are projected for the period of study using the method provided in Ohara et al. (2007). The emission rates of sulfur dioxide, black carbon, organic carbon and PM2.5 available in the global inventory are replaced with the high resolution emission inventory developed over India for the present study. The model simulates meteorological parameters, trace gases and particulate matter. Simulated mixing ratios of trace gases (Ozone, carbon monoxide, nitrogen oxides, and SO2) are compared with ground based as well as satellite observations over India with specific focus on Indo-Gangetic Plain. Simulated aerosol optical depth are in good agreement with those observed by Aerosol Robotic Network (AERONET). The vertical profiles of extinction coefficient have been compared with the Micro Pulse Lidar Network (MPLnet) data. The simulated mass concentration of BC shows very good agreement with those observed at a few ground stations. The vertical profiles of BC have also been compared with aircraft observations carried out during summer of 2008 and 2009, resulting in good agreement. This study shows that WRF-Chem model captures many important features of the observations and

  18. Retrieving the complex refractive index of atmospheric aerosols from ratios of solar spectral extinction measurements

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.; Mease, K. D.

    1978-01-01

    The technique proposed by Fymat (1976) for retrieving the complex refractive index of atmospheric aerosols using narrowband spectral transmission ratios, taken within an overall narrow spectral interval, is investigated in the case of modelled polydispersions of rural, maritime-continental, maritime-sea spray and meteoric dust aerosols. It is confirmed that for not too broad size distributions most of the information comes from a narrow size range of 'active' aerosols so that, under these circumstances, the refractive index components can indeed be retrieved essentially independently of the size distribution. For 0.1% accurate data in three colors, the technique can provide the real and imaginary components of the index respectively within 0.07% and 0.3% accuracy.

  19. Retrieving aerosol profiles through horizon shadowing and polarimetry

    NASA Astrophysics Data System (ADS)

    Videen, G.; Pavlov, A.; Zubko, E.; Konstantinov, O.; Shmirko, K.; Mayor, A.

    2017-12-01

    We report polarimetric measurements of atmospheric aerosol in evening and morning twilight over Vladivostok, Russia in late winter-early spring of 2017 using a horizon-shadowing technique. The motion of the Sun beneath the horizon changes the altitude of the boundary of the shadowed atmosphere h, making it possible to constrain the altitude of aerosol particles contributing to the polarimetric response. We investigate the degree of linear polarization P in aerosol particles at different altitudes, ranging from 0 km up to 17 km. In two out of four experiments we found significant variations of the polarimetric response (ΔP 10%) with altitude; whereas, in the other measurements, the polarization appeared nearly the same (ΔP 2-3%) throughout the entire range of the studied altitude. Polarization P was measured in the zenith direction with the scattering angle being θ 90°. At such a scattering angle, the polarization is near its maximum value Pmax. Conclusions drawn from polarimetric measurements appear in qualitative accordance with results of remote sensing with a three-wavelength lidar.

  20. Radiative Effect of Springtime Biomass-Burning Aerosols over Northern Indochina During 7-SEAS Baseline 2013 Campaign

    NASA Technical Reports Server (NTRS)

    Pani, Shantanu Kumar; Wang, Sheng-Hsiang; Lin, Neng-Huei; Lee, Chung-Te; Tsay, Si-Chee; Holben, Brent N.; Janjai, Serm; Hsiao, Ta-Chih; Chuang, Ming-Tung; Chantara, Somporn

    2016-01-01

    The direct aerosol radiative effects of biomass-burning (BB) aerosols over northern Indochina were estimated by using aerosol properties (physical, chemical, and optical) along with the vertical profile measurements from ground-based measurements with integration of an optical and a radiative transfer model during the Seven South East Asian Studies Biomass-Burning Aerosols Stratocumulus Environment: Lifecycles Interactions Experiment (7-SEASBASELInE) conducted in spring 2013. Cluster analysis of backward trajectories showed the air masses arriving at mountainous background site (Doi Ang Khang; 19.93degN, 99.05degE, 1536 m above mean sea level) in northern Indochina, mainly from near-source inland BB activities and being confined in the planetary boundary layer. The PM(sub10) and black carbon (BC)mass were 87 +/- 28 and 7 +/- 2 micrograms m(exp -3), respectively. The aerosol optical depth (AOD (sub 500) was found to be 0.26--1.13 (0.71 +/- 0.24). Finer (fine mode fraction is approximately or equal to 0.95, angstrom-exponent at 440-870 nm is approximately or equal to 1.77) and significantly absorbing aerosols(single scattering albedo is approximately or equal to 0.89, asymmetry-parameter is approximately or equal to 0.67, and absorption AOD 0.1 at 440 nm) dominated over this region. BB aerosols (water soluble and BC) were the main contributor to the aerosol radiative forcing (ARF), while others (water insoluble, sea salt and mineral dust) were negligible mainly due to their low extinction efficiency. BC contributed only 6 to the surface aerosol mass but its contribution to AOD was 12 (2 times higher). The overall mean ARF was 8.0 and -31.4 W m(exp -2) at top-of-atmosphere (TOA) and at the surface (SFC), respectively. Likely, ARF due to BC was +10.7 and -18.1 W m(exp -2) at TOA and SFC, respectively. BC imposed the heating rate of +1.4 K d(exp -1) within the atmosphere and highlighting its pivotal role in modifying the radiation budget. We propose that to upgrade our