Science.gov

Sample records for aerosol layer height

  1. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    NASA Astrophysics Data System (ADS)

    Lotteraner, Christoph; Piringer, Martin

    2016-07-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  2. Mixing-Height Time Series from Operational Ceilometer Aerosol-Layer Heights

    NASA Astrophysics Data System (ADS)

    Lotteraner, Christoph; Piringer, Martin

    2016-11-01

    A new method is described to derive mixing-height time series directly from aerosol-layer height data available from a Vaisala CL51 ceilometer. As complete as possible mixing-height time series are calculated by avoiding outliers, filling data gaps by linear interpolation, and smoothing. In addition, large aerosol-layer heights at night that can be interpreted as residual layers are not assigned as mixing heights. The resulting mixing-height time series, converted to an appropriate data format, can be used as input for dispersion calculations. Two case examples demonstrate in detail how the method works. The mixing heights calculated using ceilometer data are compared with values determined from radiosounding data at Vienna by applying the parcel, Heffter, and Richardson methods. The results of the parcel method, obtained from radiosonde profiles at noon, show the best fit to the ceilometer-derived mixing heights. For midnight radiosoundings, larger deviations between mixing heights from the ceilometer and those deduced from the potential temperature profiles of the soundings are found. We use data from two Vaisala CL51 ceilometers, operating in the Vienna area at an urban and rural site, respectively, during an overlapping period of about 1 year. In addition to the case studies, the calculated mixing-height time series are also statistically evaluated and compared, demonstrating that the ceilometer-based mixing height follows an expected daily and seasonal course.

  3. Passive remote sensing of aerosol layer height using near-UV multiangle polarization measurements

    NASA Astrophysics Data System (ADS)

    Wu, Lianghai; Hasekamp, Otto; Diedenhoven, Bastiaan; Cairns, Brian; Yorks, John E.; Chowdhary, Jacek

    2016-08-01

    We demonstrate that multiangle polarization measurements in the near-UV and blue part of the spectrum are very well suited for passive remote sensing of aerosol layer height. For this purpose we use simulated measurements with different setups (different wavelength ranges, with and without polarization, different polarimetric accuracies) as well as airborne measurements from the Research Scanning Polarimeter (RSP) obtained over the continental USA. We find good agreement of the retrieved aerosol layer height from RSP with measurements from the Cloud Physics Lidar showing a mean absolute difference of less than 1 km. Furthermore, we found that the information on aerosol layer height is provided for large part by the multiangle polarization measurements with high accuracy rather than the multiangle intensity measurements. The information on aerosol layer height is significantly decreased when the shortest RSP wavelength (410 nm) is excluded from the retrieval and is virtually absent when 550 nm is used as shortest wavelength.

  4. Developments in the Aerosol Layer Height Retrieval Algorithm for the Copernicus Sentinel-4/UVN Instrument

    NASA Astrophysics Data System (ADS)

    Nanda, Swadhin; Sanders, Abram; Veefkind, Pepijn

    2016-04-01

    The Sentinel-4 mission is a part of the European Commission's Copernicus programme, the goal of which is to provide geo-information to manage environmental assets, and to observe, understand and mitigate the effects of the changing climate. The Sentinel-4/UVN instrument design is motivated by the need to monitor trace gas concentrations and aerosols in the atmosphere from a geostationary orbit. The on-board instrument is a high resolution UV-VIS-NIR (UVN) spectrometer system that provides hourly radiance measurements over Europe and northern Africa with a spatial sampling of 8 km. The main application area of Sentinel-4/UVN is air quality. One of the data products that is being developed for Sentinel-4/UVN is the Aerosol Layer Height (ALH). The goal is to determine the height of aerosol plumes with a resolution of better than 0.5 - 1 km. The ALH product thus targets aerosol layers in the free troposphere, such as desert dust, volcanic ash and biomass during plumes. KNMI is assigned with the development of the Aerosol Layer Height (ALH) algorithm. Its heritage is the ALH algorithm developed by Sanders and De Haan (ATBD, 2016) for the TROPOMI instrument on board the Sentinel-5 Precursor mission that is to be launched in June or July 2016 (tentative date). The retrieval algorithm designed so far for the aerosol height product is based on the absorption characteristics of the oxygen-A band (759-770 nm). The algorithm has heritage to the ALH algorithm developed for TROPOMI on the Sentinel 5 precursor satellite. New aspects for Sentinel-4/UVN include the higher resolution (0.116 nm compared to 0.4 for TROPOMI) and hourly observation from the geostationary orbit. The algorithm uses optimal estimation to obtain a spectral fit of the reflectance across absorption band, while assuming a single uniform layer with fixed width to represent the aerosol vertical distribution. The state vector includes amongst other elements the height of this layer and its aerosol optical

  5. A sensitivity study of atmospheric reflectance to aerosol layer height based on multi-angular polarimetric measurements

    NASA Astrophysics Data System (ADS)

    Qie, Lili; Li, Donghui; Li, Zhengqiang; Zhang, Ying; Hou, Weizhen; Chen, Xingfeng

    2015-10-01

    The reflected Solar radiance at top of atmosphere (TOA) are, to some degree, sensitive to the vertical distribution of absorbing aerosols, especially at short wavelengths (i.e. blue and UV bands). If properly exploited, it may enable the extraction of basic information on aerosol vertical distribution. In recent years, rapid development of the advanced spectral multi-angle polarimetric satellite observation technology and aerosol inversion algorithm makes the extraction of more aerosol information possible. In this study, we perform a sensitivity analysis of the reflection function at TOA to the aerosol layer height, to explore the potential for aerosol height retrievals by using multi-angle total and polarized reflectance passive observations at short wavelength. Employing a vector doubling-adding method radiative transfer code RT3, a series of numerical experiments were conducted considering different aerosol model, optical depth (AOD), single-scattering albedo (SSA), and scale height (H), also the wavelength, solar-viewing geometry, etc. The sensitivity of both intensity and polarization signals to the aerosol layer height as well as the interacted impactions with SSA and AOD are analyzed. It's found that the sensitivity of the atmospheric reflection function to aerosol scale height increase with aerosol loading (i.e. AOD) and aerosol absorption (i.e. SSA), and decrease with wavelength. The scalar reflectance is sensitive to aerosol absorption while the polarized reflectance is more influenced by the altitude. Then the aerosol H and SSA may be derived simultaneously assuming that the total and polarized radiances in UV bands deconvolve the relative influences of height and absorption. Aerosol layer height, Atmospheric reflection function, Sensitivity, Ultraviolet (UV) band.

  6. Utilization of O4 slant column density to derive aerosol layer height from a spaceborne UV-visible hyperspectral sensor: sensitivity and case study

    NASA Astrophysics Data System (ADS)

    Park, S. S.; Kim, J.; Lee, H.; Torres, O.; Lee, K.-M.; Lee, S. D.

    2015-03-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using simulated radiances by a radiative transfer model, Linearized Discrete Ordinate Radiative Transfer (LIDORT), and Differential Optical Absorption Spectroscopy (DOAS) technique. The sensitivities of the O4 SCDs to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4 SCD at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 414 m (16.5%), 564 m (22.4%), and 1343 m (52.5%) for absorbing, dust, and non-absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution type. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). The retrieved aerosol effective heights are lower by approximately 300 m (27 %) compared to those obtained from the ground-based LIDAR measurements.

  7. Utilization of O4 slant column density to derive aerosol layer height from a space-borne UV-visible hyperspectral sensor: sensitivity and case study

    NASA Astrophysics Data System (ADS)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-02-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 1040 molecules2 cm-5, to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nm, the O4 absorption band at 477 nm is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nm is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 m for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 % of retrieved aerosol effective heights are within the error range of 1 km compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  8. Utilization of O4 Slant Column Density to Derive Aerosol Layer Height from a Space-Borne UV-Visible Hyperspectral Sensor: Sensitivity and Case Study

    NASA Technical Reports Server (NTRS)

    Park, Sang Seo; Kim, Jhoon; Lee, Hanlim; Torres, Omar; Lee, Kwang-Mog; Lee, Sang Deok

    2016-01-01

    The sensitivities of oxygen-dimer (O4) slant column densities (SCDs) to changes in aerosol layer height are investigated using the simulated radiances by a radiative transfer model, the linearized pseudo-spherical vector discrete ordinate radiative transfer (VLIDORT), and the differential optical absorption spectroscopy (DOAS) technique. The sensitivities of the O4 index (O4I), which is defined as dividing O4 SCD by 10(sup 40) molecules (sup 2) per centimeters(sup -5), to aerosol types and optical properties are also evaluated and compared. Among the O4 absorption bands at 340, 360, 380, and 477 nanometers, the O4 absorption band at 477 nanometers is found to be the most suitable to retrieve the aerosol effective height. However, the O4I at 477 nanometers is significantly influenced not only by the aerosol layer effective height but also by aerosol vertical profiles, optical properties including single scattering albedo (SSA), aerosol optical depth (AOD), particle size, and surface albedo. Overall, the error of the retrieved aerosol effective height is estimated to be 1276, 846, and 739 meters for dust, non-absorbing, and absorbing aerosol, respectively, assuming knowledge on the aerosol vertical distribution shape. Using radiance data from the Ozone Monitoring Instrument (OMI), a new algorithm is developed to derive the aerosol effective height over East Asia after the determination of the aerosol type and AOD from the MODerate resolution Imaging Spectroradiometer (MODIS). About 80 percent of retrieved aerosol effective heights are within the error range of 1 kilometer compared to those obtained from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) measurements on thick aerosol layer cases.

  9. Airborne Lidar measurements of aerosols, mixed layer heights, and ozone during the 1980 PEPE/NEROS summer field experiment

    NASA Technical Reports Server (NTRS)

    Browell, E. V.; Shipley, S. T.; Butler, C. F.; Ismail, S.

    1985-01-01

    A detailed summary of the NASA Ultraviolet Differential Absorption Lidar (UV DIAL) data archive obtained during the EPA Persistent Elevated Pollution Episode/Northeast Regional Oxidant Study (PEPE/NEROS) Summer Field Experiment Program (July through August 1980) is presented. The UV dial data set consists of remote measurements of mixed layer heights, aerosol backscatter cross sections, and sequential ozone profiles taken during 14 long-range flights onboard the NASA Wallops Flight Center Electra aircraft. These data are presented in graphic and tabular form, and they have been submitted to the PEPE/NEROS data archive on digital magnetic tape. The derivation of mixing heights and ozone profiles from UV Dial signals is discussed, and detailed intercomparisons with measurements obtained by in situ sensors are presented.

  10. 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

  11. 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

  12. The Role of Cloud Contamination, Aerosol Layer Height and Aerosol Model in the Assessment of the OMI Near-UV Retrievals Over the Ocean

    NASA Technical Reports Server (NTRS)

    Gasso, Santiago; Torres, Omar

    2016-01-01

    Retrievals of aerosol optical depth (AOD) at 388 nm over the ocean from the Ozone Monitoring Instrument (OMI) two-channel near-UV algorithm (OMAERUV) have been compared with independent AOD measurements. The analysis was carried out over the open ocean (OMI and MODerate-resolution Imaging Spectrometer (MODIS) AOD comparisons) and over coastal and island sites (OMI and AERONET, the AErosol RObotic NETwork). Additionally, a research version of the retrieval algorithm (using MODIS and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) information as constraints) was utilized to evaluate the sensitivity of the retrieval to different assumed aerosol properties. Overall, the comparison resulted in differences (OMI minus independent measurements) within the expected levels of uncertainty for the OMI AOD retrievals (0.1 for AOD less than 0.3, 30% for AOD greater than 0.3). Using examples from case studies with outliers, the reasons that led to the observed differences were examined with specific purpose to determine whether they are related to instrument limitations (i.e., pixel size, calibration) or algorithm assumptions (such as aerosol shape, aerosol height). The analysis confirms that OMAERUV does an adequate job at rejecting cloudy scenes within the instrument's capabilities. There is a residual cloud contamination in OMI pixels with quality flag 0 (the best conditions for aerosol retrieval according to the algorithm), resulting in a bias towards high AODs in OMAERUV. This bias is more pronounced at low concentrations of absorbing aerosols (AOD 388 nm approximately less than 0.5). For higher aerosol loadings, the bias remains within OMI's AOD uncertainties. In pixels where OMAERUV assigned a dust aerosol model, a fraction of them (less than 20 %) had retrieved AODs significantly lower than AERONET and MODIS AODs. In a case study, a detailed examination of the aerosol height from CALIOP and the AODs from MODIS, along with sensitivity tests, was carried out by

  13. The role of cloud contamination, aerosol layer height and aerosol model in the assessment of the OMI near-UV retrievals over the ocean

    NASA Astrophysics Data System (ADS)

    Gassó, Santiago; Torres, Omar

    2016-07-01

    Retrievals of aerosol optical depth (AOD) at 388 nm over the ocean from the Ozone Monitoring Instrument (OMI) two-channel near-UV algorithm (OMAERUV) have been compared with independent AOD measurements. The analysis was carried out over the open ocean (OMI and MODerate-resolution Imaging Spectrometer (MODIS) AOD comparisons) and over coastal and island sites (OMI and AERONET, the AErosol RObotic NETwork). Additionally, a research version of the retrieval algorithm (using MODIS and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) information as constraints) was utilized to evaluate the sensitivity of the retrieval to different assumed aerosol properties. Overall, the comparison resulted in differences (OMI minus independent measurements) within the expected levels of uncertainty for the OMI AOD retrievals (0.1 for AOD < 0.3, 30 % for AOD > 0.3). Using examples from case studies with outliers, the reasons that led to the observed differences were examined with specific purpose to determine whether they are related to instrument limitations (i.e., pixel size, calibration) or algorithm assumptions (such as aerosol shape, aerosol height). The analysis confirms that OMAERUV does an adequate job at rejecting cloudy scenes within the instrument's capabilities. There is a residual cloud contamination in OMI pixels with quality flag 0 (the best conditions for aerosol retrieval according to the algorithm), resulting in a bias towards high AODs in OMAERUV. This bias is more pronounced at low concentrations of absorbing aerosols (AOD 388 nm ˜ < 0.5). For higher aerosol loadings, the bias remains within OMI's AOD uncertainties. In pixels where OMAERUV assigned a dust aerosol model, a fraction of them (< 20 %) had retrieved AODs significantly lower than AERONET and MODIS AODs. In a case study, a detailed examination of the aerosol height from CALIOP and the AODs from MODIS, along with sensitivity tests, was carried out by varying the different assumed parameters in the

  14. Assessing Aerosol Mixed Layer Heights from the NASA Larc Airborne High Spectral Resolution Lidar (HSRL) during the Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Sawamura, P.; Collins, J. E., Jr.; Seaman, S. T.; Cook, A. L.; Harper, D. B.; Follette-Cook, M. B.; daSilva, A.; Randles, C. A.

    2014-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD, during January and February 2013 over the San Joaquin Valley of California, during September 2013 over Houston, TX and during July and August 2014 over Denver, CO. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the mixed layer (ML) height. Analysis of the ML height at these four locations is presented, including temporal and horizontal variability and comparisons between land and water, including the Chesapeake Bay and Galveston Bay. Using the ML heights, the distribution of AOT relative to the ML heights is determined, which is relevant for assessing the long-range transport of aerosols. The ML heights are also used to help relate column AOT measurements and extinction profiles to surface PM2.5 concentrations. The HSRL ML heights are also used to evaluate the performance in simulating the temporal and spatial variability of ML heights from both chemical regional models and global forecast models.

  15. Retrieving the Height of Smoke and Dust Aerosols by Synergistic Use of Multiple Satellite Sensors

    NASA Technical Reports Server (NTRS)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2016-01-01

    The Aerosol Single scattering albedo and Height Estimation (ASHE) algorithm was first introduced in Jeong and Hsu (2008) to provide aerosol layer height and single scattering albedo (SSA) for biomass burning smoke aerosols. By using multiple satellite sensors synergistically, ASHE can provide the height information over much broader areas than lidar observations alone. The complete ASHE algorithm uses aerosol data from MODIS or VIIRS, OMI or OMPS, and CALIOP. A simplified algorithm also exists that does not require CALIOP data as long as the SSA of the aerosol layer is provided by another source. Several updates have recently been made: inclusion of dust layers in the retrieval process, better determination of the input aerosol layer height from CALIOP, improvement in aerosol optical depth (AOD) for nonspherical dust, development of quality assurance (QA) procedure, etc.

  16. Variability of aerosol properties and Planetary Boundary Layer heights from airborne High Spectral Resolution Lidar, ground-based measurements, and the WRF model during CalNex and CARES

    NASA Astrophysics Data System (ADS)

    Obland, M. D.; Swanson, A. J.; Ferrare, R. A.; Burton, S. P.; Hair, J. W.; Hostetler, C. A.; Rogers, R.; Fast, J. D.; Berg, L. K.; Pekour, M. S.; Shaw, W. J.; Zaveri, R. A.; Haman, C. L.; Cook, A.; Harper, D.

    2011-12-01

    The NASA airborne High Spectral Resolution Lidar (HSRL) was deployed on board the NASA Langley Research Center's B200 aircraft to California in May and June of 2010 to aid in characterizing aerosol properties during the CalNex and CARES field missions. Measurements of aerosol extinction (at 532 nm), backscatter (at 532 and 1064 nm), and depolarization (at 532 and 1064 nm) during 31 flights and nearly 100 hours, many in coordination with other participating research aircraft, satellites, and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as properties and variability of the Planetary Boundary Layer (PBL). This work examines the variability of the extensive (dependent on aerosol type and number density) and intensive (dependent on aerosol type only) aerosol properties to aid in describing the broader context of aerosol behavior within and nearby the Sacramento and Los Angeles Basin regions. PBL heights derived from HSRL measurements will be compared with those produced by local ceilometers, radiosondes, and the Weather Research and Forecasting (WRF) model. Spatial and temporal averages of aerosol properties will be presented.

  17. Determining Aerosol Plume Height from Two GEO Imagers: Lessons from MISR and GOES

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.

    2012-01-01

    Aerosol plume height is a key parameter to determine impacts of particulate matters generated from biomass burning, wind-blowing dust, and volcano eruption. Retrieving cloud top height from stereo imageries from two GOES (Geostationary Operational Environmental Satellites) have been demonstrated since 1970's and the principle should work for aerosol plumes if they are optically thick. The stereo technique has also been used by MISR (Multiangle Imaging SpectroRadiometer) since 2000 that has nine look angles along track to provide aerosol height measurements. Knowing the height of volcano aerosol layers is as important as tracking the ash plume flow for aviation safety. Lack of knowledge about ash plume height during the 2010 Eyja'rjallajokull eruption resulted in the largest air-traffic shutdown in Europe since World War II. We will discuss potential applications of Asian GEO satellites to make stereo measurements for dust and volcano plumes.

  18. Global Distribution of Planetary Boundary Layer Height Derived from CALIPSO

    NASA Astrophysics Data System (ADS)

    Huang, J.

    2015-12-01

    The global distribution of planetary boundary layer (PBL) height, which was estimated from the attenuated back-scatter observations of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), is presented. In general, the PBL is capped by a temperature inversion that tends to trap moisture and aerosols. The gradient of back-scatter observed by lidar is almost always associated with this temperature inversion and the simultaneous decrease of moisture content. Thus, the PBL top is defined as the location of the maximum aerosol scattering gradient, which is analogous to the more conventional thermodynamic definition. The maximum standard deviation method, developed by Jordan et al. (2010), is modified and used to derive the global PBL heights. The derived PBL heights are not only consistent with the results of McGrath-Spangler and Denning (2012) but also agree well with the ground-based lidar measurements. It is found that the correlation between CALIPSO and the ground-based lidar was 0.73. The seasonal mean patterns from 4-year mid-day PBL heights over global are demonstrated. Also it is found that the largest PBL heights occur over the Tibetan Plateau and the coastal areas. The smallest PBL heights appear in the Tarim Basin and the northeast of China during the local winter. The comparison of PBL heights from CALIPSO and ECMWF under different land-cover conditions showed that, over ocean and forest surface, the PBL height estimated from the CALIPSO back-scatter climatology is larger than the ones estimated from ECMWF data. However, the PBL heights from ECMWF, over grass land and bare land surface in spring and summer are larger than the ones from CALIPSO.

  19. Retrieving the Height of Smoke and Dust Aerosols by Synergistic Use of VIIRS, OMPS, and CALIOP Observations

    NASA Technical Reports Server (NTRS)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2015-01-01

    Aerosol Single scattering albedo and Height Estimation (ASHE) algorithm was first introduced in Jeong and Hsu (2008) to provide aerosol layer height as well as single scattering albedo (SSA) for biomass burning smoke aerosols. One of the advantages of this algorithm was that the aerosol layer height can be retrieved over broad areas, which had not been available from lidar observations only. The algorithm utilized aerosol properties from three different satellite sensors, i.e., aerosol optical depth (AOD) and Ångström exponent (AE) from Moderate Resolution Imaging Spectroradiometer (MODIS), UV aerosol index (UVAI) from Ozone Monitoring Instrument (OMI), and aerosol layer height from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Here, we extend the application of the algorithm to Visible Infrared Imaging Radiometer Suite (VIIRS) and Ozone Mapping and Profiler Suite (OMPS) data. We also now include dust layers as well as smoke. Other updates include improvements in retrieving the AOD of nonspherical dust from VIIRS, better determination of the aerosol layer height from CALIOP, and more realistic input aerosol profiles in the forward model for better accuracy.

  20. BOREAS AFM-6 Boundary Layer Height Data

    NASA Technical Reports Server (NTRS)

    Wilczak, James; Hall, Forrest G. (Editor); Newcomer, Jeffrey A. (Editor); Smith, David E. (Technical Monitor)

    2000-01-01

    The Boreal Ecosystem-Atmosphere Study (BOREAS) Airborne Fluxes and Meteorology (AFM)-6 team from National Oceanic and Atmospheric Adminsitration/Environment Technology Laboratory (NOAA/ETL) operated a 915-MHz wind/Radio Acoustic Sounding System (RASS) profiler system in the Southern Study Area (SSA) near the Old Jack Pine (OJP) site. This data set provides boundary layer height information over the site. The data were collected from 21 May 1994 to 20 Sep 1994 and are stored in tabular ASCII files. The boundary layer height data are available from the Earth Observing System Data and Information System (EOSDIS) Oak Ridge National Laboratory (ORNL) Distributed Active Archive Center (DAAC). The data files are available on a CD-ROM (see document number 20010000884).

  1. Retrieving the height of smoke and dust aerosols by synergistic use of VIIRS, OMPS, and CALIOP observations

    NASA Astrophysics Data System (ADS)

    Lee, Jaehwa; Hsu, N. Christina; Bettenhausen, Corey; Sayer, Andrew M.; Seftor, Colin J.; Jeong, Myeong-Jae

    2015-08-01

    This study extends the application of the previously developed Aerosol Single-scattering albedo and layer Height Estimation (ASHE) algorithm, which was originally applied to smoke aerosols only, to both smoke and dust aerosols by including nonspherical dust properties in the retrieval process. The main purpose of the algorithm is to derive aerosol height information over wide areas using aerosol products from multiple satellite sensors simultaneously: aerosol optical depth (AOD) and Ångström exponent from the Visible Infrared Imaging Radiometer Suite (VIIRS), UV aerosol index from the Ozone Mapping and Profiler Suite (OMPS), and total backscatter coefficient profile from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). The case studies suggest that the ASHE algorithm performs well for both smoke and dust aerosols, showing root-mean-square error of the retrieved aerosol height as compared to CALIOP observations from 0.58 to 1.31 km and mean bias from -0.70 to 1.13 km. In addition, the algorithm shows the ability to retrieve single-scattering albedo to within 0.03 of Aerosol Robotic Network inversion data for moderate to thick aerosol loadings (AOD of ~1.0). For typical single-layered aerosol cases, the estimated uncertainty in the retrieved height ranges from 1.20 to 1.80 km over land and from 1.15 to 1.58 km over ocean when favorable conditions are met. Larger errors are observed for multilayered aerosol events, due to the limited sensitivities of the passive sensors to such cases.

  2. Vegetation fires in the himalayan region - Aerosol load, black carbon emissions and smoke plume heights

    NASA Astrophysics Data System (ADS)

    Vadrevu, Krishna Prasad; Ellicott, Evan; Giglio, Louis; Badarinath, K. V. S.; Vermote, Eric; Justice, Chris; Lau, William K. M.

    2012-02-01

    In this study, we investigate the potential of multi-satellite datasets for quantifying the biomass burning emissions from the Himalayan region. A variety of satellite products were used for characterizing fire events including active fire counts, burnt areas, aerosol optical depth (AOD) variations, aerosol index and smoke plume heights. Results from the MODerate-resolution Imaging Spectroradiometer (MODIS) fire product suggest March-June as the major fire season with the peak during the April. An average of 3908 fire counts per year were recorded with sixty four percent of the fires occurring in the low elevation areas in the Himalayan Region. We estimate average burnt areas of 1129 sq. km, with the black carbon emissions of 431 Mg, per year. The mean AOD (2005-2010) was 0.287 ± 0.105 (one sigma) with peak values in May. Correlation analysis between the fire counts and AOD resulted in a Pearson correlation coefficient of 0.553; the correlation between the FRP and AOD is relatively weaker ( r = 0.499). Planetary boundary layer height retrieved from the Modern Era Retrospective-Analysis For Research And Applications (MERRA) product suggests typical PBL height of 1000-1200 m during the April-May peak biomass burning season. Cloud-Aerosol Lidar Orthogonal Polarisation (CALIOP) retrievals show the extent of smoke plume heights beyond the planetary boundary layer during the peak biomass burning month of April. However, comparison of fires in the Himalayan region with other regions and comparisons to aerosol index data from the Ozone Monitoring Instrument (OMI) suggest smoke plumes reaching less than 3 km. Our results on fires and smoke plume height relationships provide valuable information for addressing aerosol transport in the region.

  3. Impact of meteorology on fine aerosols at Lucas Heights, Australia

    NASA Astrophysics Data System (ADS)

    Crawford, Jagoda; Chambers, Scott; Cohen, David D.; Williams, Alastair; Griffiths, Alan; Stelcer, Eduard; Dyer, Leisa

    2016-11-01

    Ion Beam Analysis (IBA) techniques were used to assign nine years of PM2.5 observations to seven source types, at Lucas Heights, a topographically complex urban fringe site of Sydney. The highest contributions to total PM2.5 were from motor vehicles (Autos, 26.3%), secondary sulfur (2ndryS, 23.7%), a mixture of industry and aged sea air (IndSaged, 20.6%), and smoke (Smoke, 13.7%). The Autos contribution was highest in winter, whereas 2ndryS was highest in summer, indicating that mitigation measures targeting SO2 release in summer and vehicle exhaust in winter would be most effective in reducing the PM2.5 concentrations at this site. Since concentrations of particulate matter can be significantly affected by local meteorology, generalised additive model (GAM) techniques were employed to investigate relationships between PM2.5 source types and meteorological conditions. The GAM predictors used included: time (seasonal to inter-annual variations), mixing layer depth, temperature, relative humidity, wind speed, wind direction, and atmospheric pressure. Meteorological influences on PM2.5 variability were found to be 58% for soil dust, 46% for Autos, 41% for total PM2.5, and 35% for 2ndryS. Effects were much smaller for other source types. Temperature was found to be an important variable for the determination of total PM2.5, 2ndryS, IndSaged, Soil and Smoke, indicating that future changes in temperature are likely to have an associated change in aerosol concentrations. However, the impact on different source types varied. Temperature had the highest impact on 2ndryS (sometimes more than a factor of 4 increase for temperatures above 25 °C compared to temperatures under 10 °C) and IndSaged, being predominantly secondary aerosols formed in the atmosphere from precursors, whereas wind speed and wind direction were more important for the determination of vehicle exhaust and fresh sea salt concentrations. The marginal effect of relative humidity on 2ndryS increased up to

  4. Mixed Layer Heights Derived from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Scarino, Amy J.; Burton, Sharon P.; Ferrare, Rich A.; Hostetler, Chris A.; Hair, Johnathan W.; Obland, Michael D.; Rogers, Raymond R.; Cook, Anthony L.; Harper, David B.; Fast, Jerome; Dasilva, Arlindo; Benedetti, Angela

    2012-01-01

    The NASA airborne High Spectral Resolution Lidar (HSRL) has been deployed on board the NASA Langley Research Center's B200 aircraft to several locations in North America from 2006 to 2012 to aid in characterizing aerosol properties for over fourteen field missions. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) during 349 science flights, many in coordination with other participating research aircraft, satellites, and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as properties and variability of the Mixing Layer (ML) height. We describe the use of the HSRL data collected during these missions for computing ML heights and show how the HSRL data can be used to determine the fraction of aerosol optical thickness within and above the ML, which is important for air quality assessments. We describe the spatial and temporal variations in ML heights found in the diverse locations associated with these experiments. We also describe how the ML heights derived from HSRL have been used to help assess simulations of Planetary Boundary Layer (PBL) derived using various models, including the Weather Research and Forecasting Chemistry (WRF-Chem), NASA GEOS-5 model, and the ECMWF/MACC models.

  5. Comparison of Observed and Simulated Boundary Layer Height Estimates during Discover-Aq July 2011

    NASA Astrophysics Data System (ADS)

    Flynn, C.; Pickering, K. E.; Ferrare, R. A.; Scarino, A. J.; Delgado, R.; Martins, D. K.; Lenschow, D. H.; Loughner, C.; Thompson, A. M.

    2013-12-01

    The first deployment of the NASA Earth Venture -1 DISCOVER-AQ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality) project was conducted during July 2011 in the Baltimore-Washington region. The P-3B aircraft provided in situ vertical profiles of meteorological quantities, trace gases, and aerosols over six Maryland Department of the Environment (MDE) air quality monitoring sites over fourteen flight days. The UC-12 aircraft provided continuous remote sensing observations of aerosols over its flight track with the High Spectral Resolution Lidar (HSRL). Additionally, several MDE sites were equipped with the ground-based Micro-Pulse Lidar (MPL) instrument, also providing continuous, remotely sensed aerosol observations, and two sites launched ozonesondes during the campaign. A major goal of DISCOVER-AQ is to understand the processes linking trace gas column abundances to surface concentrations, including vertical mixing in the planetary boundary layer (PBL). In support of this goal, estimates of the PBL height output by the WRF/CMAQ model system (ACM2 PBL scheme and Pleim-Xiu surface layer scheme) were compared to observational estimates of PBL height during the July 2011 deployment. WRF/CMAQ typically demonstrated a high bias in PBL height relative to the meteorological PBL height estimates (those based on the potential temperature profile measured by the P-3B or ozonesondes), while the model demonstrated a low bias relative to PBL height estimates based on the aerosol backscatter profile (HSRL and MPL data). Additionally, the model tended to overpredict the PBL height on days when the PBL was well mixed, and underpredicted when the PBL was poorly mixed. Preliminary results from an intercomparison of the WRF model run with six different PBL schemes (ACM2, YSU, MYJ, MYNN, QNSE, and BouLac schemes) will also be presented.

  6. Outer layer effects in wind-farm boundary layers: Coriolis forces and boundary layer height

    NASA Astrophysics Data System (ADS)

    Allaerts, Dries; Meyers, Johan

    2015-11-01

    In LES studies of wind-farm boundary layers, scale separation between the inner and outer region of the atmospheric boundary layer (ABL) is frequently assumed, i.e., wind turbines are presumed to fall within the inner layer and are not affected by outer layer effects. However, modern wind turbine and wind farm design tends towards larger rotor diameters and farm sizes, which means that outer layer effects will become more important. In a prior study, it was already shown for fully-developed wind farms that the ABL height influences the power performance. In this study, we use the in-house LES code SP-Wind to investigate the importance of outer layer effects on wind-farm boundary layers. In a suite of LES cases, the ABL height is varied by imposing a capping inversion with varying inversion strengths. Results indicate the growth of an internal boundary layer (IBL), which is limited in cases with low inversion layers. We further find that flow deceleration combined with Coriolis effects causes a change in wind direction throughout the farm. This effect increases with decreasing boundary layer height, and can result in considerable turbine wake deflection near the end of the farm. The authors are supported by the ERC (ActiveWindFarms, grant no: 306471). Computations were performed on VSC infrastructiure (Flemish Supercomputer Center), funded by the Hercules Foundation and the Flemish Government-department EWI.

  7. Lidar observations of high-altitude aerosol layers (cirrus clouds)

    NASA Astrophysics Data System (ADS)

    Deleva, Atanaska D.; Grigorov, Ivan V.

    2013-03-01

    Aerosols, clouds and aerosol-cloud interactions are recognized as the key factors influencing the climate. Clouds are the primary modulators of the Earth's radiative budget. This paper focuses on the detection of high-altitude aerosol layers in the troposphere over mid-latitude lidar station in Sofia, Bulgaria. They are situated in the height-region 6 km÷16 km, with thickness in the range 0.2 km÷5 km and have varying optical characteristics. On the basis of the general utilized classification of the Cirrus clouds, high values of the calculated atmospheric backscatter coefficient and Angströmexponent estimation results we conclude that the registered strongly scattered aerosol layers are Cirrus clouds. Lidar measurements are performed with an aerosol lidar, equipped with Nd:YAG laser at wavelengths 532 nm and 1064 nm. Mainly, lidar data are presented in terms of vertical atmospheric backscatter coefficient profiles. We also include 2Dcolormap in height-time coordinates build on the basis of so called range corrected signals. It shows in general changes of the aerosol stratification over the lidar station during the measurement period. We employed HYSPLIT backward trajectories and DREAM forecasts to analyze the lidar profile outlines and characterize the events during which Cirrus cloud samples were observed. So was remarked that most of the results were obtained during Saharan dust long-way transport over the city of Sofia. Reported experimental examples are extracted from regular lidar investigations of the atmosphere within the frame of European project EARLINET.

  8. Application of continuous remote sensing of mixing layer height for assessment of airport air quality

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Helmis, Costas; Emeis, Stefan; Sgouros, George; Kurtenbach, Ralf; Wiesen, Peter; Münkel, Christoph; Jahn, Carsten; Hoffmann, Maria; Anamaterou, Evi; O'Connor, Michael

    2010-10-01

    The assessment of airport air quality requires not only the knowledge of the emissions and the temporal and spatial distribution of meteorological parameters like wind direction and wind speed but also of the mixing layer height, because this variable controls the vertical space for rapid mixing of near-surface pollutants. It was demonstrated that the lowest stable layer or temperature inversion limits the vertical exchange of primary pollutants emitted at or near the surface and thus controls the near-surface pollutant concentrations. Remote sensing is a suitable tool to determine mixing layer height continuously as was demonstrated in urban and sub-urban areas (Hannover, Munich, Budapest, Augsburg) as well as at airports (Zurich, Paris CDG, Mexico City International Airport, Athens International Airport). The Vaisala ceilometer LD40 was used which is an eye-safe commercial lidar and designed originally to detect cloud base heights and vertical visibility for aviation safety purposes. These measurements of the vertical aerosol distribution are routinely retrieved for mixing layer height estimation by using software which was improved continuously and compared with radiosonde data. Further, mixing layer height was determined by remote sensing with a combination of a Doppler- SODAR (Sound Detection and Ranging), a RASS (Radio Acustic Sounding System) and in-situ measurements. Vertical wind, temperature and turbulence parameter profiles up to 1500 m maximum were measured by this method too. Some results of interpretation of measured data at Athens International Airport will be discussed as the influence of mixing layer height upon airport air quality and estimation of the airport emission source strengths.

  9. Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

    NASA Astrophysics Data System (ADS)

    Summa, D.; Di Girolamo, P.; Stelitano, D.; Cacciani, M.

    2013-12-01

    The planetary boundary layer (PBL) includes the portion of the atmosphere which is directly influenced by the presence of the earth's surface. Aerosol particles trapped within the PBL can be used as tracers to study the boundary-layer vertical structure and time variability. As a result of this, elastic backscatter signals collected by lidar systems can be used to determine the height and the internal structure of the PBL. The present analysis considers three different methods to estimate the PBL height. The first method is based on the determination of the first-order derivative of the logarithm of the range-corrected elastic lidar signals. Estimates of the PBL height for specific case studies obtained through this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are based on the determination of the first-order derivative of the range-corrected rotational Raman lidar signals. This latter approach results to be successfully applicable also in the afternoon-evening decaying phase of the PBL, when the effectiveness of the approach based on the elastic lidar signals may be compromised or altered by the presence of the residual layer. Results from these different approaches are compared and discussed in the paper, with a specific focus on selected case studies collected by the University of Basilicata Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS).

  10. Characterization of the planetary boundary layer height and structure by Raman lidar: comparison of different approaches

    NASA Astrophysics Data System (ADS)

    Summa, D.; Di Girolamo, P.; Stelitano, D.; Cacciani, M.

    2013-06-01

    The Planetary Boundary Layer (PBL) includes the portion of the atmosphere which is directly influenced by the presence of the Earth's surface. Aerosol particles trapped within the PBL can be used as tracers to study the boundary-layer vertical structure and time variability. As a result of this, elastic backscatter signals collected by lidar systems can be used to determine the height and the internal structure of the PBL. The present analysis considers three different methods to estimate the PBL height. A first method is based on the determination of the first order derivative of the logarithm of the range-corrected elastic lidar signals. Estimates of the PBL height for specific case studies obtained from this approach are compared with simultaneous estimates from the potential temperature profiles measured by radiosondes launched simultaneously to lidar operation. Additional estimates of the boundary layer height are based on the determination of the first order derivative of the range-corrected rotational Raman lidar signals. This latter approach results to be successfully applicable also in the afternoon-evening decaying phase of the PBL, when the effectiveness of the approach based on the elastic lidar signals may be compromised or altered by the presence of the residual layer. Results from these different approaches are compared and discussed in the paper, with a specific focus on selected case studies collected by the University of Basilicata Raman lidar system BASIL during the Convective and Orographically-induced Precipitation Study (COPS).

  11. A height resolved global view of dust aerosols from the first year CALIPSO lidar measurements

    NASA Astrophysics Data System (ADS)

    Liu, Dong; Wang, Zhien; Liu, Zhaoyan; Winker, Dave; Trepte, Charles

    2008-08-01

    Based on the first year of CALIPSO lidar measurements under cloud-free conditions, a height-resolved global distribution of dust aerosols is presented for the first time. Results indicate that spring is the most active dust season, during which ˜20% and ˜12% of areas between 0 and 60°N are influenced by dust at least 10% and 50% of the time, respectively. In summer within 3-6 km, ˜8.3% of area between 0 and 60°N is impacted by dust at least 50% of the time. Strong seasonal cycles of dust layer vertical extent are observed in major source regions, which are similar to the seasonal variation of the thermally driven boundary layer depth. The arid and semiarid areas in North Africa and the Arabian Peninsula are the most persistent and prolific dust sources. African dust is transported across the Atlantic all yearlong with strong seasonal variation in the transport pathways mainly in the free troposphere in summer and at the low altitudes in winter. However, the trans-Atlantic dust is transported at the low altitudes is important for all seasons, especially transported further cross the ocean. The crossing Atlantic dusty zones are shifted southward from summer to winter, which is accompanied by a similar southward shift of dust-generating areas over North Africa. The Taklimakan and Gobi deserts are two major dust sources in East Asia with long-range transport mainly occurring in spring. The large horizontal and vertical coverage of dust aerosols indicate their importance in the climate system through both direct and indirect aerosol effects.

  12. Two years of free-tropospheric aerosol layers observed over Portugal by lidar

    NASA Astrophysics Data System (ADS)

    PreißLer, J.; Wagner, F.; Guerrero-Rascado, J. L.; Silva, A. M.

    2013-05-01

    Multi-wavelength Raman light detection and ranging (lidar) observations were analyzed, which were performed in Évora, Portugal, during more than 2 years on a regular basis in the framework of the European Aerosol Research Lidar Network (EARLINET). An aerosol characterization in terms of the lidar ratios at 355 and 532 nm and the extinction and backscatter related Ångström exponents is presented. Aerosol layers in the free troposphere were classified according to their origin. Clear differences in the intensive optical properties were found for layers of mineral dust from the Sahara and from Asia, of anthropogenic aerosol from Europe and from North America, as well as of biomass burning smoke from the Iberian Peninsula and from North America, respectively. In general, the mean Ångström exponents of aerosol layers of the same type, but from closer source regions, were smaller than those from aerosol layers transported over a longer distance. This hints at the deposition of large particles along the transportation path, especially for anthropogenic aerosol and mineral dust. Besides, the seasonal behavior of aerosol in the free troposphere over Évora was studied. Seventy-three percent of the detected layers were observed during spring and summer. On average, the layers were highest in summer with an overall mean layer height of (3.8 ±1.9) km above sea level (asl), and lowest in winter with (2.3 ±0.9) km asl.

  13. Notes on an Internal Boundary-Layer Height Formula

    NASA Astrophysics Data System (ADS)

    Savelyev, Sergiya.; Taylor, Petera.

    The derivation of the Panofsky-Dutton internal boundary-layer(IBL) height formula has been revisited. We propose that the upwindroughness length (rather than downwind) should be used in theformula and that a turbulent vertical velocity (w) ratherthan the surface friction velocity (u*) should be considered asthe appropriate scaling for the rate of propagation ofdisturbances into the turbulent flow. A published set ofwind-tunnel and atmospheric data for neutral stratification hasbeen used to investigate the influence of the magnitude ofroughness change on the IBL height.

  14. Atmospheric Boundary Layer Height Evolution with Lidar in Buenos Aires from 2008 to 2011

    NASA Astrophysics Data System (ADS)

    Pawelko, Ezequiel Eduardo; Salvador, Jacobo Omar; Ristori, Pablo Roberto; Pallotta, Juan Vicente; Otero, Lidia Ana; Quel, Eduardo Jaime

    2016-06-01

    The analysis of the atmospheric boundary layer top height evolution is obtained from 2008 to 2011 in Buenos Aires using the multiwavelength lidar located at CEILAP (CITEDEF-CONICET) (34°33' S; 58°30' W; 17 m asl). Algorithms recognition based on covariance wavelet transform are applied to obtain seasonal statistics. This method is being evaluated for use in the Lidar Network in Argentina and it is being deployed in Patagonia region currently. The technique operates in real time in both low and high aerosol loads and with almost no human supervision.

  15. Composition and physical properties of the Asian Tropopause Aerosol Layer and the North American Tropospheric Aerosol Layer

    PubMed Central

    Yu, Pengfei; Toon, Owen B; Neely, Ryan R; Martinsson, Bengt G; Brenninkmeijer, Carl A M

    2015-01-01

    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 the ATAL is mostly composed of sulfates, surface-emitted organics, and secondary organics; the NATAL is mostly composed of sulfates and secondary organics. 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. Key Points The Asian Tropopause Aerosol Layer is composed of sulfate, primary organics, and secondary organics The North American Tropospheric Aerosol Layer is mostly composed of sulfate and secondary organics Aerosol Optical Depth of Asian Tropopause Aerosol Layer increases by 0.002 from 2000 to 2010 PMID:26709320

  16. Effects of explosively venting aerosol-sized particles through earth-containment systems on the cloud-stabilization height

    SciTech Connect

    Dyckes, G.W.

    1980-07-01

    A method of approximating the cloud stabilization height for aerosol-sized particles vented explosively through earth containment systems is presented. The calculated values for stabilization heights are in fair agreement with those obtained experimentally.

  17. Atmospheric Aerosol and Thermal Structure in the Boundary Layer Over the Los Angeles Basin

    NASA Technical Reports Server (NTRS)

    Johnson, Warren B.

    1973-01-01

    A field study using a mobile lidar was recently conducted in the L. A. Basin, California, to (1) examine the relationship between the vertical aerosol and the thermal structure, and (2) map the vertical aerosol structure in the atmospheric boundary layer over the basin. These data are needed for use in the development of a mixing-depth submodel required for photochemical air Quality simulation models. Toward these ends, a series of lidar aerosol measurements in conjunction with balloon and aircraft temperature soundings were taken at a site in El Monte, and in a mobile mode along a 90-mile freeway loop between El Monte, Santa Monica, and Long Beach. The lidar data are presented in the form of time-height and distance-height cross sections. The results indicate that, although aerosol concentrations are frequently present above the base of the marine inversion, these are generally in stratified layers in contrast to the more uniform nature of the lower convective layer, permitting the mixing depth to be distinguished on this basis. The lidar-derived mixing depths are well correlated (within 100 m) with daytime temperature inversions. Other significant features shown by the lidar data include large Basin-wide mixing-depth variations, waves with amplitudes of 200-300 m and wavelengths of 1000-1500 m on the lower aerosol layer, and apparent aerosol "chimneys" with overrunning in the vicinity of convergence zones.

  18. Planetary Boundary Layer and aerosol interactions over the Indian sub-continent

    NASA Astrophysics Data System (ADS)

    Patil, M. N.; Patil, S. D.; Waghmare, R. T.; Dharmaraj, T.

    2014-05-01

    Aerosols, both natural as well as anthropogenic, affect the radiative forcing of Earth's climate and reduce surface albedo. The Planetary Boundary Layer (PBL) height, which depends upon surface heat budget, is analyzed considering the increase in green house gases (GHGs) from pre-industrial to post-industrial era. The PBL climatology shows deeper PBL during pre-monsoon and summer monsoon seasons as compared to post-monsoon and winter. The PBL height has decreased in post-industrial decade compared to pre-industrial decade. The PBL height reduction is due to increasing aerosol and GHGs' concentrations in the recent decades, which causes surface warming and upper tropospheric cooling. Similarly, due to higher loading of the volcanic aerosol injected from the low latitude eruptions, the atmospheric circulation has been affected.

  19. Pulse height response of an optical particle counter to monodisperse aerosols

    NASA Technical Reports Server (NTRS)

    Wilmoth, R. G.; Grice, S. S.; Cuda, V.

    1976-01-01

    The pulse height response of a right angle scattering optical particle counter has been investigated using monodisperse aerosols of polystyrene latex spheres, di-octyl phthalate and methylene blue. The results confirm previous measurements for the variation of mean pulse height as a function of particle diameter and show good agreement with the relative response predicted by Mie scattering theory. Measured cumulative pulse height distributions were found to fit reasonably well to a log normal distribution with a minimum geometric standard deviation of about 1.4 for particle diameters greater than about 2 micrometers. The geometric standard deviation was found to increase significantly with decreasing particle diameter.

  20. Aerosol - cloud - water vapor relations for cloud systems of different heights

    NASA Astrophysics Data System (ADS)

    Stathopoulos, Stavros; Kourtidis, Konstantinos; Georgoulias, Aristeidis

    2016-04-01

    Here we examine the annual and seasonal aerosol - cloud relations over three major urban clusters of China, for different cloud heights and atmospheric water vapor amounts, using a decade of Aerosol Optical Depth at 550nm (AOD), Cloud Cover (CC), Cloud Optical Depth (COD), Water Vapor (WV) and Cloud Top Pressure (CTP) data from the MODIS instrument. Over all regions (spanning from temperate to tropical monsoon climates) and for all seasons, CC is found to increase with AOD, WV and cloud height. Aerosols, at low WV environments and under constant cloud height, have less impact on CC than at high WV environments. In addition, AOD has a varying influence on COD depending on CTP. Finally, COD is found to increase with height for low and middle height clouds, and with increasing AOD, especially at low AOD, the latter being in line with the expected first indirect effect. This research has been financed under the FP7 Programme MarcoPolo (Grand Number 606953, Theme SPA.2013.3.2-01).

  1. Influences on the Height of the Stable Boundary Layer as seen in LES

    SciTech Connect

    Kosovic, B; Lundquist, J

    2004-06-15

    Climate models, numerical weather prediction (NWP) models, and atmospheric dispersion models often rely on parameterizations of planetary boundary layer height. In the case of a stable boundary layer, errors in boundary layer height estimation can result in gross errors in boundary-layer evolution and in prediction of turbulent mixing within the boundary layer.

  2. Dust layer profiling using an aerosol dropsonde

    NASA Astrophysics Data System (ADS)

    Ulanowski, Zbigniew; Kaye, Paul Henry; Hirst, Edwin; Wieser, Andreas; Stanley, Warren

    2015-04-01

    Routine meteorological data is obtained in the atmosphere using disposable radiosondes, giving temperature, pressure, humidity and wind speed. Additional measurements are obtained from dropsondes, released from research aircraft. However, a crucial property not yet measured is the size and concentration of atmospheric particulates, including dust. Instead, indirect measurements are employed, relying on remote sensing, to meet the demands from areas such as climate research, air quality monitoring, civil emergencies etc. In addition, research aircraft can be used in situ, but airborne measurements are expensive, and aircraft use is restricted to near-horizontal profiling, which can be a limitation, as phenomena such as long-range transport depend on the vertical distribution of aerosol. The Centre for Atmospheric and Instrumentation Research at University of Hertfordshire develops light-scattering instruments for the characterization of aerosols and cloud particles. Recently a range of low-cost, miniature particle counters has been created, intended for use with systems such as disposable balloon-borne radiosondes, dropsondes, or in dense ground-based sensor networks. Versions for different particle size ranges exist. They have been used for vertical profiling of aerosols such as mineral dust or volcanic ash. A disadvantage of optical particle counters that sample through a narrow inlet is that they can become blocked, which can happen in cloud, for example. Hence, a different counter version has been developed, which can have open-path geometry, as the sensing zone is defined optically rather than being delimited by the flow system. This counter has been used for ground based air-quality monitoring around Heathrow airport. The counter has also been adapted for use with radiosondes or dropsondes. The dropsonde version has been successfully tested by launching it from research aircraft together with the so-called KITsonde, developed at the Karlsruhe Institute of

  3. Radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer and its feedback on the haze formation

    NASA Astrophysics Data System (ADS)

    Wei, Chao; Su, Hang; Cheng, Yafang

    2016-04-01

    Planetary boundary layer (PBL) plays a key role in air pollution dispersion and influences day-to-day air quality. Some studies suggest that high aerosol loadings during severe haze events may modify PBL dynamics by radiative effects and hence enhance the development of haze. This study mainly investigates the radiative effects of tropospheric aerosols on the evolution of the atmospheric boundary layer by conducting simulations with Weather Research and Forecasting single-column model (WRF-SCM). We find that high aerosol loading in PBL depressed boundary layer height (PBLH). But the magnitude of the changes of PBLH after adding aerosol loadings in our simulations are small and can't explain extreme high aerosol concentrations observed. We also investigate the impacts of the initial temperature and moisture profiles on the evolution of PBL. Our studies show that the impact of the vertical profile of moisture is comparable with aerosol effects.

  4. Tropospheric ozone and aerosols measured by airborne lidar during the 1988 Arctic boundary layer experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Butler, Carolyn F.; Kooi, Susan A.

    1991-01-01

    Ozone (O3) and aerosol distributions were measured from an aircraft using a differential absorption lidar (DIAL) system as part of the 1988 NASA Global Tropospheric Experiment - Arctic Boundary Layer Experiment (ABLE-3A) to study the sources and sinks of gases and aerosols over the tundra regions of Alaska during the summer. The tropospheric O3 budget over the Arctic was found to be strongly influenced by stratospheric intrusions. Regions of low aerosol scattering and enhanced O3 mixing ratios were usually correlated with descending air from the upper troposphere or lower stratosphere. Several cases of continental polar air masses were examined during the experiment. The aerosol scattering associated with these air masses was very low, and the atmospheric distribution of aerosols was quite homogeneous for those air masses that had been transported over the ice for greater than or = 3 days. The transition in O3 and aerosol distributions from tundra to marine conditions was examined several times. The aerosol data clearly show an abrupt change in aerosol scattering properties within the mixed layer from lower values over the tundra to generally higher values over the water. The distinct differences in the heights of the mixed layers in the two regions was also readily apparent. Several cases of enhanced O3 were observed during ABLE-3 in conjunction with enhanced aerosol scattering in layers in the free atmosphere. Examples are presented of the large scale variations of O3 and aerosols observed with the airborne lidar system from near the surface to above the tropopause over the Arctic during ABLE-3.

  5. A Comparison of Aerosol-Layer and Convective Boundary-Layer Structure over a Mountain Range during STAAARTE '97

    SciTech Connect

    De Wekker, Stephan; Steyn, D. G.; Nyeki, Stephan

    2004-11-01

    The temporal evolution and spatial structure of the aerosol layer (AL) height as observed with an airborne downlooking lidar over the Swiss Alps was investigated with a three dimensional mesoscale numerical model and a particle dispersion model. Convective boundary layer (CBL) heights were derived from the mesoscale model output, and the behavior of surface-released particles was investigated with the particle dispersion model. While a previous investigation, using data from the same field study, equated the observed AL height with the CBL height, the results of the current investigation indicate that there is a considerable difference between AL and CBL heights caused by mixing and transport processes between the CBL and the free atmosphere. CBL heights show a more terrain-following behavior and are lower than AL heights. We argue that processes causing the difference between AL and CBL heights are common over mountainous terrain and that the AL height is a length scale that needs t o be considered in air pollution studies in mountainous terrain.

  6. Stereoscopic Height and Wind Retrievals for Aerosol Plumes with the MISR INteractive eXplorer (MINX)

    NASA Technical Reports Server (NTRS)

    Nelson, D.L.; Garay, M.J.; Kahn, Ralph A.; Dunst, Ben A.

    2013-01-01

    The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the Terra satellite acquires imagery at 275-m resolution at nine angles ranging from 0deg (nadir) to 70deg off-nadir. This multi-angle capability facilitates the stereoscopic retrieval of heights and motion vectors for clouds and aerosol plumes. MISR's operational stereo product uses this capability to retrieve cloud heights and winds for every satellite orbit, yielding global coverage every nine days. The MISR INteractive eXplorer (MINX) visualization and analysis tool complements the operational stereo product by providing users the ability to retrieve heights and winds locally for detailed studies of smoke, dust and volcanic ash plumes, as well as clouds, at higher spatial resolution and with greater precision than is possible with the operational product or with other space-based, passive, remote sensing instruments. This ability to investigate plume geometry and dynamics is becoming increasingly important as climate and air quality studies require greater knowledge about the injection of aerosols and the location of clouds within the atmosphere. MINX incorporates features that allow users to customize their stereo retrievals for optimum results under varying aerosol and underlying surface conditions. This paper discusses the stereo retrieval algorithms and retrieval options in MINX, and provides appropriate examples to explain how the program can be used to achieve the best results.

  7. Radiative Impacts of Elevated Aerosol Layers from Different Origins

    NASA Astrophysics Data System (ADS)

    Sauer, D. N.; Weinzierl, B.; Gasteiger, J.; Heimerl, K.

    2014-12-01

    Aerosol particles are omnipresent in the Earth's atmosphere and have important impacts on weather and climate by their effects on the atmospheric radiative balance. With the advent of more and more sophisticated representations of atmospheric processes in earth system models, the lack of reliable input data on aerosols leads to significant uncertainties in the prediction of future climate scenarios. In recent years large discrepancies in radiative forcing estimates from aerosol layers in modeling studies have been revealed emphasizing the need for detailed and systematic observations of aerosols. Airborne in-situ measurements represent an important pillar for validating both model results and retrievals of aerosol distributions and properties from remote sensing methods on global scales. However, detailed observations are challenging and therefore are subject to substantial uncertainties themselves. Here we use data from airborne in-situ measurements of elevated aerosol layers from various field experiments in different regions of the world. The data set includes Saharan mineral dust layers over Africa, the Atlantic Ocean and the Caribbean from the SALTRACE and the SAMUM campaigns as well as long-range transported biomass burning aerosol layers from wild fires in the Sahel region and North America measured over the tropical Atlantic Ocean, Europe and the Arctic detected during SAMUM2, CONCERT2011, DC3 and ACCESS 2012. We aim to characterize the effects of the measured aerosol layers, in particular with respect to ageing, mixing state and vertical structure, on the overall atmospheric radiation budget as well as local heating and cooling rates. We use radiative transfer simulations of short and long-wave radiation and aerosol optical properties derived in a consistent way from the in-situ observations of microphysical properties using T-matrix calculations. The results of this characterization will help to improve the parameterization of the effects of elevated

  8. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry.

  9. Real-Time Characterization of Aerosol Particle Composition above the Urban Canopy in Beijing: Insights into the Interactions between the Atmospheric Boundary Layer and Aerosol Chemistry.

    PubMed

    Sun, Yele; Du, Wei; Wang, Qingqing; Zhang, Qi; Chen, Chen; Chen, Yong; Chen, Zhenyi; Fu, Pingqing; Wang, Zifa; Gao, Zhiqiu; Worsnop, Douglas R

    2015-10-01

    Despite extensive efforts into the characterization of air pollution during the past decade, real-time characterization of aerosol particle composition above the urban canopy in the megacity Beijing has never been performed to date. Here we conducted the first simultaneous real-time measurements of aerosol composition at two different heights at the same location in urban Beijing from December 19, 2013 to January 2, 2014. The nonrefractory submicron aerosol (NR-PM1) species were measured in situ by a high-resolution aerosol mass spectrometer at near-ground level and an aerosol chemical speciation monitor at 260 m on a 325 m meteorological tower in Beijing. Secondary aerosol showed similar temporal variations between ground level and 260 m, whereas much weaker correlations were found for the primary aerosol. The diurnal evolution of the ratios and correlations of aerosol species between 260 m and the ground level further illustrated a complex interaction between vertical mixing processes and local source emissions on aerosol chemistry in the atmospheric boundary layer. As a result, the aerosol compositions at the two heights were substantially different. Organic aerosol (OA), mainly composed of primary OA (62%), at the ground level showed a higher contribution to NR-PM1 (65%) than at 260 m (54%), whereas a higher concentration and contribution (15%) of nitrate was observed at 260 m, probably due to the favorable gas-particle partitioning under lower temperature conditions. In addition, two different boundary layer structures were observed, each interacting differently with the evolution processes of aerosol chemistry. PMID:26348650

  10. Chemical analysis of aerosol in the Venusian cloud layer by reaction gas chromatography on board the Vega landers

    NASA Technical Reports Server (NTRS)

    Gelman, B. G.; Drozdov, Y. V.; Melnikov, V. V.; Rotin, V. A.; Khokhlov, V. N.; Bondarev, V. B.; Dolnikov, G. G.; Dyachkov, A. V.; Nenarokov, D. F.; Mukhin, L. M.

    1986-01-01

    The experiment on sulfuric acid aerosol determination in the Venusian cloud layer on board the Vega landers is described. An average content of sulfuric acid of approximately 1 mg/cu m was found for the samples taken from the atmosphere at heights from 63 to 48 km and analyzed with the SIGMA-3 chromatograph. Sulfur dioxide (SO2) was revealed in the gaseous sample at the height of 48 km. From the experimental results and blank run measurements, a suggestion is made that the Venusian cloud layer aerosol consists of more complicated particles than the sulfuric acid water solution does.

  11. Dependence of the drizzle growth process on the cloud top height and its relevance to the aerosol vertical profile

    NASA Astrophysics Data System (ADS)

    Kawamoto, K.; Suzuki, K.

    2013-12-01

    Transitional processes among cloud droplets, drizzle and raindrops are still uncertain and more efforts are required for the better understanding. In this situation, difference in the drizzle growth process was examined according to the cloud top height using the CloudSat and MODIS synergetic datasets. From the CloudSat products such as 2B-GEOPROF, 2B-TAU, ECMWF-AUX, only one-layered water clouds whose top temperatures were warmer than 273K were extracted over China (a circular area having a diameter of 1800km of the center at 35°N and 120°E) and over ocean (a circular area having a diameter of 1500km of the center at 35°N and 150°E). Then a threshold of 3km of the cloud top height was adopted to divide the extracted clouds into upper and lower cases. First, the probability distribution functions (PDF) of the cloud droplet number density (Nc) and the effective particle radius (Re) were calculated for these four cases (land/ocean/upper/lower). Nc was obtained assuming the adiabatic liquid water content from MODIS-derived cloud optical depth and Re. Oceanic clouds had fewer Nc than land clouds, and almost the same for upper and lower cases. Land clouds had more Nc for the lower case than for the higher case. On the other hand, oceanic clouds had larger Re than land clouds, and almost the same for upper and lower cases. Land clouds had smaller Re for the lower case than for the higher case. These results quite agreed with our existing knowledge on the vertical profile of the aerosol number concentration over ocean (pristine) and land (polluted). Although the number of aerosol particles is fewer and almost the same regardless of the height over the ocean, it is more near the surface and it rapidly decreases according to the height over the land. Next, examining PDF of the radar reflectivity (Ze), we found that although PDFs of Ze were almost the same for oceanic clouds regardless of the cloud top height, PDF of land lower clouds were less frequent at around from

  12. Separating aerosol microphysical effects and satellite measurement artifacts of the relationships between warm rain onset height and aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Zhu, Yannian; Rosenfeld, Daniel; Yu, Xing; Li, Zhanqing

    2015-08-01

    The high resolution (375 m) of the Visible Infrared Imaging Radiometer Suite on board the Suomi National Polar-Orbiting Partnership satellite allows retrieving relatively accurately the vertical evolution of convective cloud drop effective radius (re) with height or temperature. A tight relationship is found over SE Asia and the adjacent seas during summer between the cloud-free aerosol optical depth (AOD) and the cloud thickness required for the initiation of warm rain, as represented by the satellite-retrieved cloud droplet re of 14 µm, for a subset of conditions that minimize measurement artifacts. This cloud depth (ΔT14) is parameterized as the difference between the cloud base temperature and the temperature at the height where re exceeds 14 µm (T14). For a unit increase of AOD, the height of rain initiation is increased by about 5.5 km. The concern of data artifacts due to the increase in AOD near clouds was mitigated by selecting only scenes with cloud fraction (CF) < 0.1. For CF > 0.1 and ΔT14 > ~20°C, the increase of ΔT14 gradually levels off with further increase of AOD, possibly because the AOD is enhanced by aerosol upward transport and detrainment through the clouds below the T14 isotherm. The bias in the retrieved re due to the different geometries of solar illumination was also quantified. It was shown that the retrievals are valid only for backscatter views or when avoiding scenes with significant amount of cloud self-shadowing. These artifacts might have contributed to past reported relationships between cloud properties and AOD.

  13. Enhancement of atmospheric radiation by an aerosol layer

    NASA Technical Reports Server (NTRS)

    Michelangeli, Diane V.; Yung, Yuk L.; Shia, Run-Lie; Eluszkiewicz, Janusz; Allen, Mark; Crisp, David

    1992-01-01

    The presence of a stratospheric haze layer may produce increases in both the actinic flux and the irradiance below this layer. Such haze layers result from the injection of aerosol-forming material into the stratosphere by volcanic eruptions. Simple heuristic arguments show that the increase in flux below the haze layer, relative to a clear sky case, is a consequence of 'photon trapping'. The magnitude of these flux perturbations, as a function of aerosol properties and illumination conditions, is explored with a new radiative transfer model that can accurately compute fluxes in an inhomogeneous atmosphere with nonconservative scatterers having arbitrary phase function. One calculated consequence of the El Chichon volcanic eruption is an increase in the midday surface actinic flux at 20 deg N latitude, summer, by as much as 45 percent at 2900 A. This increase in flux in the UV-B wavelength range was caused entirely by aerosol scattering, without any reduction in the overhead ozone column.

  14. Enhancement of atmospheric radiation by an aerosol layer.

    PubMed

    Michelangeli, D V; Allen, M; Yung, Y L; Shia, R L; Crisp, D; Eluszkiewicz, J

    1992-01-20

    The presence of a stratospheric haze layer may produce increases in both the actinic flux and the irradiance below this layer. Such haze layers result from the injection of aerosol-forming material into the stratosphere by volcanic eruptions. Simple heuristic arguments show that the increase in flux below the haze layer, relative to a clear sky case, is a consequence of "photon trapping." We explore the magnitude of these flux perturbations, as a function of aerosol properties and illumination conditions, with a new radiative transfer model that can accurately compute fluxes in an inhomogenous atmosphere with nonconservative scatterers having arbitrary phase function. One calculated consequence of the El Chichon volcanic eruption is an increase in the midday surface actinic flux at 20 degrees N latitude, summer, by as much as 45% at 2900 angstroms. This increase in flux in the UV-B wavelength range was caused entirely by aerosol scattering, without any reduction in the overhead ozone column.

  15. A multi-decadal history of biomass burning plume heights identified using aerosol index measurements

    NASA Astrophysics Data System (ADS)

    Guan, H.; Esswein, R.; Lopez, J.; Bergstrom, R.; Warnock, A.; Follette-Cook, M.; Fromm, M.; Iraci, L. T.

    2010-07-01

    We have quantified the relationship between Aerosol Index (AI) measurements and plume height for young biomass burning plumes using coincident Ozone Monitoring Instrument (OMI) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) measurements. This linear relationship allows the determination of high-altitude plumes wherever AI data are available, and it provides a data set for validating global fire plume heights in chemistry transport models. We find that all plumes detected from June 2006 to February 2009 with an AI value ≥9 are located at altitudes higher than 5 km. Older high-altitude plumes have lower AI values than young plumes at similar altitudes. We have examined available AI data from the OMI and TOMS instruments (1978-2009) and find that large AI plumes occur more frequently over North America than over Australia or Russia/Northeast Asia. According to the derived relationship, during this time interval, 181 plumes, in various stages of their evolution, reached altitudes above 8 km.

  16. MISR observations at dust source regions: 10-year analysis of aerosol properties and plume heights.

    NASA Astrophysics Data System (ADS)

    Kalashnikova, Olga; Sokolik, Irina; Garay, Michael; Wu, Dong

    Multiangle remote sensing, in particular from Terra/MISR, provides a unique, independent source of data for study dust emission and transport. MISR/Terra is an imaging instrument that uses combination of multi-spectral and multi-angle data to retrieve aerosol properties and aerosol plume heights. A number of validation studies have shown that MISR provides reliable optical depth values over the bright desert. We use the 10-year aerosol data record from the Multi-angle Imaging SpectroRadiometer (MISR) aboard the Terra satellite to investigate the inter-annual and seasonal variability of dust loadings and properties as retrieved by MISR at selected dust source regions. In particular, we examine the Taklamakan, East and Central Gobi regions in Asia, and Mauritania desert and Bodélé Basin regions in Africa. Within each ee selected region, the analysis was performed to examine the multi-annual mean and variability of the aerosol optical depth and particle properties, taking into account the effects of MISR sampling and cloud coverage. To avoid the gridding and averaging effects as much as possible we use the instantaneous Level 2 MISR data for the analysis. We use AERONET data and other independent measurements where available to supplement and constrain MISR product. In addition to the optical depth/property analysis, we report 10-year climatology of dust plume heights over Bodélé Basin as function of the distance from the source. We demonstrate that, ee while there are some effects of large-scale dynamics on dust loadings and heights, the various differences in anomaly time series (including month-to-month differences) reveal the role of meso-scale systems specific to the each source region. These source-specific differences provide valuable information for testing/validating the regional dust transport models. The results will be presented and interpreted in the context of atmospheric dynamics variability, including variability of meteorological regimes in dust

  17. Variability of Biomass Burning Aerosols Layers and Near Ground

    NASA Astrophysics Data System (ADS)

    Vasilescu, Jeni; Belegante, Livio; Marmureanu, Luminita; Toanca, Flori

    2016-06-01

    The aim of this study is to characterize aerosols from both chemical and optical point of view and to explore the conditions to sense the same particles in elevated layers and at the ground. Three days of continuous measurements using a multi-wavelength depolarization lidar(RALI) and a C-ToF-AMS aerosol mass spectrometer are analyzed. The presence of smoke particles was assessed in low level layers from RALI measurements. Chemical composition of submicronic volatile/semi-volatile aerosols at ground level was monitored by the CTOF AMS Several episodes of biomass burning aerosols have been identified by both techniques due to the presence of specific markers (f60, linear particle depolarization ratio, Ängström exponent).

  18. Lidar measurements of sub-visible aerosol layers in the free troposphere at a tropical coastal station in Trivandrum, India

    NASA Astrophysics Data System (ADS)

    Veerabuthiran, Sangaipillai; Satyanarayana, Malladi; Sreeja, Rajappan; Presennakumar, Bhargavan; Muraleedharen Nair, Sivarama Pillai; Ramakrishna Rao, Duggirala; Pillai Mohankumar, Santhibhavan Vasudevan

    2006-12-01

    Lidar observations had been conducted to study the long-range transport of aerosol and their effect at tropical station, Trivandrum during the period of 2001-2003. The presence of aerosol layers was observed on many days below about 5 km during the above period. The monthly values of aerosol extinction coefficient profile showed the presence of aerosol layer in the height region up to about 5 km during the summer monsoon periods. However, during the Asian winter monsoon period the aerosol layers were observed in the altitude region between 0.6 and 3 km. The extinction values were high in the winter season and were typically found to be 3.4×10-4 m-1. The aerosol optical depth was calculated by integrating the extinction values in the aerosol layer region and it was found to be between 0.2 and 0.35. The plausible reasons for the formation of these layers were explained using the wind circulation pattern and air back trajectories.

  19. Quasi-biennial oscillation of the tropical stratospheric aerosol layer

    NASA Astrophysics Data System (ADS)

    Hommel, R.; Timmreck, C.; Giorgetta, M. A.; Graf, H. F.

    2015-05-01

    This study describes how aerosol in an aerosol-coupled climate model of the middle atmosphere is influenced by the quasi-biennial oscillation (QBO) during times when the stratosphere is largely unperturbed by volcanic material. In accordance with satellite observations, the vertical extent of the stratospheric aerosol layer in the tropics is modulated by the QBO by up to 6 km, or ~ 35% of its mean vertical extent between 100-7 hPa (about 16-33 km). Its largest vertical extent lags behind the occurrence of strongest QBO westerlies. The largest reduction lags behind maximum QBO easterlies. Strongest QBO signals in the aerosol surface area (30 %) and number densities (up to 100% e.g. in the Aitken mode) are found in regions where aerosol evaporates, that is above the 10 hPa pressure level (~ 31 km). Positive modulations are found in the QBO easterly shear, negative modulations in the westerly shear. Below 10 hPa, in regions where the aerosol mixing ratio is largest (50-20 hPa, or ~ 20-26 km), in most of the analysed parameters only moderate statistically significant QBO signatures (< 10%) have been found. QBO signatures in the model prognostic aerosol mixing ratio are significant at the 95% confidence level throughout the tropical stratosphere where modelled mixing ratios exceed 0.1 ppbm. In some regions of the tropical lower stratosphere the QBO signatures in other analysed parameters are partly not statistically significant. Peak-to-peak amplitudes of the QBO signature in the prognostic mixing ratios are up to twice as large as seasonal variations in the region where aerosols evaporate and between 70-30 hPa. Between the tropical tropopause and 70 hPa the QBO signature is relatively weak and seasonal variations dominate the variability of the simulated Junge layer. QBO effects on the upper lid of the tropical aerosol layer turn the quasi-static balance between processes maintaining the layer's vertical extent into a cyclic balance when considering this dominant mode

  20. Aerosol model development for environmental monitoring in the coastal atmosphere surface layer

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady A.; Matvienko, Gennady G.

    2007-06-01

    Extinction of radiation in the marine boundary layer is dominated by scattering and absorption due to atmospheric aerosol. It is known, that the extinction of optical radiation visible and near IR spectra in the marine surface layer is determined mainly by scattering and absorption atmospheric aerosol. It influences on a dependence of spectral transmission and extinction both natural, and artificial light that is of interest for a wide range of problems, in particular for radiating problems at studying laws of climate formation, and for lines of the applications connected to the forecast of a signal power in coastal conditions at an estimation of EO systems characteristics. This is important to optical retrievals from satellite, remote sensing at environmental monitoring, backscatter of light to space (including climate forcing), cloud properties etc. In unpolluted regions the greatest effects on near shore scattering extinction will be a result of sea-salt from breaking waves and variations in relative humidity. The role of breaking waves appears to be modulated by wind, tide, swell, wave spectra and coastal conditions. These influences will be superimposed upon aerosol generated by open ocean sea-salt aerosol that varies with wind speed. The focus of our study is the extinction and optical effects due to aerosol in a specific coastal region. This involves linking coastal physical properties to oceanic and meteorological parameters in order to develop predictive algorithms that describe 3-D aerosol structure and variability. The aerosol microphysical model of the marine and coastal atmosphere surface layer is considered. The model distinctive feature is parameterization of amplitude and width of the modes as functions of fetch and wind speed. In the paper the dN/dr behavior depending at change meteorological parameters, heights above sea level, fetch, wind speed and RH is show. On the basis of the developed model with usage of Mie theory for spheres the

  1. Planetary Boundary Layer (PBL) Heights Derived From NASA Langley Airborne High Spectral Resolution Lidar (HSRL) Data Acquired During TexAQS/GoMACCS, CHAPS, and MILAGRO

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Cook, A.; Harper, D.; Obland, M. D.; Rogers, R. R.

    2007-12-01

    The NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) was deployed on the NASA Langley B-200 King Air aircraft in the Mexico City metropolitan area during the Mega-city Initiative: Local and Global Research Observations (MILAGRO) campaign in March 2006; in the Houston metropolitan area during the Texas Air Quality Study (TexAQS)/Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS) in August and September 2006; and in the Oklahoma City area during Cumulus Humilis Aerosol Processing Study (CHAPS) in June 2007. The HSRL instrument measures profiles of aerosol extinction, backscatter and depolarization. The height of the Planetary Boundary Layer was derived by identifying sharp gradients in the HSRL 532-nm aerosol backscatter signal profiles using an automated technique based on Brooks (2003) [I.M. Brooks, Finding Boundary Layer Top: Application of Wavelet Covariance Transform to Lidar Backscatter Profiles. Journal of Atmospheric and Oceanic Technology 20, 1092-1105, 2003]. The technique uses a Haar wavelet covariance transform with multiple wavelet dilation values to adapt to non-ideal conditions where there can be gradients in the background signals and the boundary layer can be ill defined. The technique also identifies the top and bottom of the transition (i.e. entrainment) zone. We have further modified the algorithm to find PBL heights using HSRL backscatter data acquired during GoMACCS and MILAGRO, where complex terrain and overlying aerosol layers further complicate identifying the boundary layer. In addition, PBL heights are derived from HSRL backscatter data acquired during the CHAPS campaign, in another urban environment where the terrain is not as complex. We will describe the algorithm modifications we have made and show boundary layer heights and transition zone thicknesses for HSRL measurements over the Oklahoma City, Houston, and Mexico City areas during CHAPS, TexAQS/GoMACCS, and MILAGRO.

  2. A multi-decadal history of biomass burning plume heights identified using aerosol index measurements

    NASA Astrophysics Data System (ADS)

    Guan, H.; Esswein, R.; Lopez, J.; Bergstrom, R.; Warnock, A.; Follette-Cook, M.; Fromm, M.; Iraci, L.

    2010-01-01

    We have quantified the relationship between Aerosol Index (AI) measurements and plume height for young biomass burning plumes using coincident OMI and CALIPSO measurements. This linear relationship allows the determination of high-altitude plumes wherever AI data are available, and it provides a data set for validating global fire plume injection heights in chemistry transport models. We find that all plumes detected from June 2006 to February 2009 with an AI value ≥9 are located at altitudes higher than 5 km. Older high-altitude plumes have lower AI values than young plumes at similar altitudes. We have examined available AI data from the OMI and TOMS instruments (1978-2009) and find that large AI plumes occur more frequently over North America than over Australia or Russia/Northeast Asia. According to the derived relationship, during this time interval, 181 plumes reached altitudes above 8 km. One hundred and thirty-two had injection heights ≥8 km but below 12 km, and 49 were lofted to 12 km or higher, including 14 plumes injected above 16 km.

  3. Spatiotemporal Variability in Observations of Urban Mixed-Layer Heights from Surface-based Lidar Systems during DISCOVER-AQ 2011

    NASA Astrophysics Data System (ADS)

    Lewis, J. R.; Banks, R. F.; Berkoff, T.; Welton, E. J.; Joseph, E.; Thompson, A. M.; Decola, P.; Hegarty, J. D.

    2015-12-01

    Accurate characterization of the planetary boundary layer height is crucial for numerical weather prediction, estimating pollution emissions and modeling air quality. More so, given the increasing trend in global urban populations, there is a growing need to improve our understanding of the urban boundary layer structure and development. The Deriving Information on Surface conditions from COlumn and VERtically resolved observations relevant to Air Quality (DISCOVER-AQ) 2011 field campaign, which took place in the Baltimore-Washington DC region, offered a unique opportunity to study boundary layer processes in an urban area using a geographically dense collection of surface-based lidar systems (see figure). Lidars use aerosols as tracers for atmospheric boundary layer dynamics with high vertical and temporal resolutions. In this study, we use data from two permanent Micropulse Lidar Network (MPLNET) sites and five field deployed Micropulse lidar (MPL) systems in order to observe spatiotemporal variations in the daytime mixed layer height. We present and compare lidar-derived retrievals of the mixed layer height using two different methods. The first method uses the wavelet covariance transform and a "fuzzy logic" attribution scheme in order to determine the mixed layer height. The second method uses an objective approach utilizing a time-adaptive extended Kalman filter. Independent measurements of the boundary layer height are obtained using profiles from ozonesonde launches at the Beltsville and Edgewood sites for comparison with lidar observations.

  4. The seasonal cycle of the mixing layer height and its impact on black carbon concentrations in the Kathmandu Valley (Nepal)

    NASA Astrophysics Data System (ADS)

    Mues, Andrea; Rupakheti, Maheswar; Hoor, Peter; Bozem, Heiko; Münkel, Christoph; Lauer, Axel; Butler, Tim

    2016-04-01

    The properties and the vertical structure of the mixing layer as part of the planetary boundary layer are of key importance for local air quality. They have a substantial impact on the vertical dispersion of pollutants in the lower atmosphere and thus on their concentrations near the surface. In this study, ceilometer measurements taken within the framework of the SusKat project (Sustainable Atmosphere for the Kathmandu Valley) are used to investigate the mixing layer height in the Kathmandu Valley, Nepal. The applied method is based on the assumption that the aerosol concentration is nearly constant in the vertical and distinctly higher within the mixing layer than in the air above. Thus, the height with the steepest gradient within the ceilometer backscatter profile marks the top of the mixing layer. Ceilometer and black carbon (BC) measurements conducted from March 2013 through February 2014 provide a unique and important dataset for the analysis of the meteorological and air quality conditions in the Kathmandu Valley. In this study the mean diurnal cycle of the mixing layer height in the Kathmandu Valley for each season (pre-monsoon, monsoon, post-monsoon and winter season) and its dependency on the meteorological situation is investigated. In addition, the impact of the mixing layer height on the BC concentration is analyzed and compared to the relevance of other important processes such as emissions, horizontal advection and deposition. In all seasons the diurnal cycle is typically characterized by low mixing heights during the night, gradually increasing after sun rise reaching to maximum values in the afternoon before decreasing again. Seasonal differences can be seen particularly in the height of the mixing layer, e.g. from on average 153/1200 m (pre-monsoon) to 241/755 m (monsoon season) during the night/day, and the duration of enhanced mixing layer heights during daytime (around 12 hours (pre-monsoon season) to 8 hours (winter)). During the monsoon

  5. The Two-Column Aerosol Project: Phase I—Overview and impact of elevated aerosol layers on aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Berg, Larry K.; Fast, Jerome D.; Barnard, James C.; Burton, Sharon P.; Cairns, Brian; Chand, Duli; Comstock, Jennifer M.; Dunagan, Stephen; Ferrare, Richard A.; Flynn, Connor J.; Hair, Johnathan W.; Hostetler, Chris A.; Hubbe, John; Jefferson, Anne; Johnson, Roy; Kassianov, Evgueni I.; Kluzek, Celine D.; Kollias, Pavlos; Lamer, Katia; Lantz, Kathleen; Mei, Fan; Miller, Mark A.; Michalsky, Joseph; Ortega, Ivan; Pekour, Mikhail; Rogers, Ray R.; Russell, Philip B.; Redemann, Jens; Sedlacek, Arthur J.; Segal-Rosenheimer, Michal; Schmid, Beat; Shilling, John E.; Shinozuka, Yohei; Springston, Stephen R.; Tomlinson, Jason M.; Tyrrell, Megan; Wilson, Jacqueline M.; Volkamer, Rainer; Zelenyuk, Alla; Berkowitz, Carl M.

    2016-01-01

    The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study designed to provide a comprehensive data set that can be used to investigate a number of important climate science questions, including those related to aerosol mixing state and aerosol radiative forcing. The study was designed to sample the atmosphere between and within two atmospheric columns; one fixed near the coast of North America (over Cape Cod, MA) and a second moveable column over the Atlantic Ocean several hundred kilometers from the coast. The U.S. Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) was deployed at the base of the Cape Cod column, and the ARM Aerial Facility was utilized for the summer and winter intensive observation periods. One important finding from TCAP is that four of six nearly cloud-free flight days had aerosol layers aloft in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA high-spectral resolution lidar (HSRL-2). These layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. In addition, while there was a great deal of spatial and day-to-day variability in the aerosol chemical composition and optical properties, no systematic differences between the two columns were observed.

  6. Global aerosol modeling with the online NMMB/BSC Chemical Transport Model: sensitivity to fire injection height prescription and secondary organic aerosol schemes

    NASA Astrophysics Data System (ADS)

    Spada, Michele; Jorba, Oriol; Pérez García-Pando, Carlos; Tsigaridis, Kostas; Soares, Joana; Obiso, Vincenzo; Janjic, Zavisa; Baldasano, Jose M.

    2015-04-01

    We develop and evaluate a fully online-coupled model simulating the life-cycle of the most relevant global aerosols (i.e. mineral dust, sea-salt, black carbon, primary and secondary organic aerosols, and sulfate) and their feedbacks upon atmospheric chemistry and radiative balance. Following the capabilities of its meteorological core, the model has been designed to simulate both global and regional scales with unvaried parameterizations: this allows detailed investigation on the aerosol processes bridging the gap between global and regional models. Since the strong uncertainties affecting aerosol models are often unresponsive to model complexity, we choose to introduce complexity only when it clearly improves results and leads to a better understanding of the simulated aerosol processes. We test two important sources of uncertainty - the fires injection height and secondary organic aerosol (SOA) production - by comparing a baseline simulation with experiments using more advanced approaches. First, injection heights prescribed by Dentener et al. (2006, ACP) are compared with climatological injection heights derived from satellite measurements and produced through the Integrated Monitoring and Modeling System For Wildland Fires (IS4FIRES). Also global patterns of SOA produced by the yield conversion of terpenes as prescribed by Dentener et al. (2006, ACP) are compared with those simulated by the two-product approach of Tsigaridis et al. (2003, ACP). We evaluate our simulations using a variety of observations and measurement techniques. Additionally, we discuss our results in comparison to other global models within AEROCOM and ACCMIP.

  7. Measurements and Parametrizations of the Atmospheric Boundary-Layer Height at Dome C, Antarctica

    NASA Astrophysics Data System (ADS)

    Pietroni, Ilaria; Argentini, Stefania; Petenko, Igor; Sozzi, Roberto

    2012-04-01

    An experimental campaign, Study of the Atmospheric Boundary Layer Environmental at Dome C, was held during 2005 at the French-Italian station of Concordia at Dome C. Ground-based remote sensors, as well as in situ instrumentation, were used during the experimental campaign. The measurements allowed the direct estimation of the polar atmospheric boundary-layer height and the test of several parametrizations for the unstable and stable boundary layers. During the months of January and February, weak convection was observed while, during the polar night, a long-lived stable boundary layer occurred continuously. Under unstable stratification the mixing-layer height was determined using the sodar backscattered echoes and potential temperature profiles. The two estimations are highly correlated, with the mixing height ranging between 30 and 350 m. A simple prognostic one-dimensional model was used to estimate the convective mixing-layer height, with the correlation coefficient between observations and model results being 0.66. The boundary-layer height under stable conditions was estimated from radiosounding profiles as the height where the critical Richardson number is reached; values between 10 and 150 m were found. A visual inspection of potential temperature profiles was also used as further confirmation of the experimental height; the results of the two methods are in good agreement. Six parametrizations from the literature for the stable boundary-layer height were tested. Only the parametrization that considers the long-lived stable boundary layer and takes into account the interaction of the stable layer with the free atmosphere is in agreement with the observations.

  8. Elevated aerosol layers and their radiative impact over Kanpur during monsoon onset period

    NASA Astrophysics Data System (ADS)

    Sarangi, Chandan; Tripathi, S. N.; Mishra, A. K.; Goel, A.; Welton, E. J.

    2016-07-01

    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 (σ) 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 σ 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 (˜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 aerosol loading

  9. Results from long-term detection of mixing layer height: ceilometer and comparison with Radio-Acoustic Sounding System

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Emeis, Stefan; Jahn, Carsten; Tuma, Michael; Münkel, Christoph; Suppan, Peter

    2012-11-01

    The mixing layer height (MLH) is an important factor which influences exchange processes of ground level emissions. The continuous knowledge of MLH is supporting the understanding of processes directing air quality. If the MLH is located near to the ground, which occurs mainly during winter and night-time, air pollution can be high due to a strongly limited air mass dilution. Since 2006 different methods for long-term continuous remote sensing of mixing layer height (MLH) are operated in Augsburg. The Vaisala ceilometers LD40 and CL31 are used which are eye-safe commercial mini-lidar systems. The ceilometer measurements provide information about the range-dependent aerosol concentration; gradient minima within this profile mark the borders of mixed layers. Special software for these ceilometers provides routine retrievals of lower atmosphere layering from vertical profiles of laser backscatter data. The radiosonde data from the station Oberschleissheim near Munich (about 50 km away from Augsburg city) are also used for MLH determination. The profile behavior of relative humidity (strong decrease) and virtual potential temperature (inversion) of the radiosonde agree mostly well with the MLH indication from ceilometer laser backscatter density gradients. A RASS (Radio-Acoustic Sounding System) from Metek is applied which detects the height of a turbulent layer characterized by high acoustic backscatter intensities due to thermal fluctuations and a high variance of the vertical velocity component as well as the vertical temperature profile from the detection of acoustic signal propagation and thus temperature inversions which mark atmospheric layers. These data of RASS measurements are the input for a software-based determination of MLH. A comparison of the results of the remote sensing methods during simultaneous measurements was performed. The information content of the different remote sensing instruments for MLH in dependence from different weather classes was

  10. Aerosols optical propertites in Titan's Detached Haze Layer

    NASA Astrophysics Data System (ADS)

    Seignovert, Benoît; Rannou, Pascal; Lavvas, Panayotis; Cours, Thibaud; West, Robert A.

    2016-06-01

    Titan's Detached Haze Layer (DHL) first observed in 1983 by Rages and Pollack during the Voyager 2 [1] is a consistent spherical haze feature surrounding Titan's upper atmosphere and detached from the main haze. Since 2005, the Imaging Science Subsystem (ISS) instrument on board the Cassini mission performs a continuous survey of the Titan's atmosphere and confirmed its persistence at 500 km up to the equinox (2009) before its drop and disappearance in 2012 [2]. Previous analyses showed, that this layer corresponds to the transition area between small spherical aerosols and large fractal aggregates and play a key role in the aerosols formation in Titan's atmosphere [3-5]. In this study we perform UV photometric analyses on ISS observations taken from 2005 to 2007 based on radiative transfer inversion to retrieve aerosols particles properties in the DHL (bulk and monomer size, fractal dimension and local density).

  11. Lidar Investigation of Tropical Nocturnal Boundary Layer Aerosols and Cloud Macrophysics

    SciTech Connect

    Manoj, M. G.; Devara, PC S.; Taraphdar, Sourav

    2013-10-01

    Observational evidence of two-way association between nocturnal boundary layer aerosols and cloud macrophysical properties under different meteorological conditions is reported in this paper. The study has been conducted during 2008-09 employing a high space-time resolution polarimetric micro-pulse lidar over a tropical urban station in India. Firstly, the study highlights the crucial role of boundary layer aerosols and background meteorology on the formation and structure of low-level stratiform clouds in the backdrop of different atmospheric stability conditions. Turbulent mixing induced by the wind shear at the station, which is associated with a complex terrain, is found to play a pivotal role in the formation and structural evolution of nocturnal boundary layer clouds. Secondly, it is shown that the trapping of energy in the form of outgoing terrestrial radiation by the overlying low-level clouds can enhance the aerosol mixing height associated with the nocturnal boundary layer. To substantiate this, the long-wave heating associated with cloud capping has been quantitatively estimated in an indirect way by employing an Advanced Research Weather Research and Forecasting (WRF-ARW) model version 2.2 developed by National Center for Atmospheric Research (NCAR), Colorado, USA, and supplementary data sets; and differentiated against other heating mechanisms. The present investigation as well establishes the potential of lidar remote-sensing technique in exploring some of the intriguing aspects of the cloud-environment relationship.

  12. Stratocumulus cloud thickening beneath layers of absorbing smoke aerosol

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.

    2010-08-01

    Marine stratocumulus cloud properties, and the free-tropospheric environment above them, are examined in NASA A-train satellite data for cases where smoke from seasonal burning of the West African savannah overlay the persistent southeast Atlantic stratocumulus cloud deck. CALIPSO space-borne lidar observations show that features identified as layers of aerosol occur predominantly between 2 km and 4 km altitude with double the frequency of occurrence of aerosol features in the boundary layer. Layers identified as cloud features occur predominantly below 1.5 km altitude and beneath the layer of elevated smoke aerosol. The diurnal mean shortwave heating rates attributable to the absorption of solar energy in the aerosol layer is nearly 1.5 K d-1 for an aerosol optical thickness value of 1, and increases to 1.8 K d-1 when the smoke resides above clouds owing to the additional component of upward solar radiation reflected by the cloud. As a consequence of this heating, the 700 hPa air temperature above the cloud deck is warmer by approximately 1 K on average for cases where smoke is present above the cloud compared to cases without smoke above cloud. The warmer conditions in the free-troposphere above the cloud during smoke events coincide with cloud liquid water path values that are greater by 20 g m-2 and cloud tops that are lower by approximately 50 m for overcast conditions compared to smoke-free periods. The observed thickening and subsidence of the cloud layer are consistent with published results of large-eddy simulations showing that solar absorption by smoke above stratocumulus clouds increases the buoyancy of free-tropospheric air above the temperature inversion capping the boundary layer. Increased buoyancy inhibits the entrainment of dry air through the cloud-top, thereby helping to preserve humidity and cloud cover in the boundary layer. The greater liquid water path for cases of smoke overlaying cloud implies a negative semi-direct radiative forcing of

  13. On the source of organic acid aerosol layers above clouds.

    PubMed

    Sorooshian, Armin; Lu, Miao-Ling; Brechtel, Fred J; Jonsson, Haflidi; Feingold, Graham; Flagan, Richard C; Seinfeld, John H

    2007-07-01

    During the July 2005 Marine Stratus/Stratocumulus Experiment (MASE) and the August-September 2006 Gulf of Mexico Atmospheric Composition and Climate Study (GoMACCS), the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Twin Otter probed aerosols and cumulus clouds in the eastern Pacific Ocean off the coast of northern California and in southeastern Texas, respectively. An on-board particle-into-liquid sampler (PILS) quantified inorganic and organic acid species with < or = 5-min time resolution. Ubiquitous organic aerosol layers above cloud with enhanced organic acid levels were observed in both locations. The data suggest that aqueous-phase reactions to produce organic acids, mainly oxalic acid, followed by droplet evaporation is a source of elevated organic acid aerosol levels above cloud. Oxalic acid is observed to be produced more efficiently relative to sulfate as the cloud liquid water content increases, corresponding to larger and less acidic droplets. As derived from large eddy simulations of stratocumulus underthe conditions of MASE, both Lagrangian trajectory analysis and diurnal cloudtop evolution provide evidence that a significant fraction of the aerosol mass concentration above cloud can be accounted for by evaporated droplet residual particles. Methanesulfonate data suggest that entrainment of free tropospheric aerosol can also be a source of organic acids above boundary layer clouds.

  14. Global Measurement of Junge Layer Stratospheric Aerosol with OMPS/LP. Scattering Properties and Particle Size

    NASA Astrophysics Data System (ADS)

    Rault, D. F.; Bhartia, P. K.

    2014-12-01

    The OMPS/LP was launched on board the NPP space platform in October 2011. Over the past two years, the OMPS/LP was used to retrieve the global distribution of ozone and aerosol. The paper will describe the aerosol product, which NASA is presently preparing for public release. The current OMPS/LP aerosol product consists of latitude-altitude curtains along the NPP Sun-synchronous orbit, from cloud top to about 40 km. These curtains extend from local sunrise in Southern polar region to local sunset in Northern polar region. Aerosol extinctions are produced at five distinct wavelengths, namely 513, 525, 670, 750 and 870 nm, with a sampling of 1 km in vertical direction and 1 degree latitude in the along-track direction. The OMPS/LP aerosol dataset is fairly large, with 7000 vertical profiles produced each day for each wavelength. The aerosol product will be presented in terms of extinction monthly median values and mean Angstrom coefficient (particle size). Over the past two years, the Junge layer was affected by several events such as volcanic eruptions (Nabro and Kelut) and a meteor (Chelyabinsk), the effects of which are clearly visible in the OMPS/LP dataset. The Asian Tropopause Aerosol Layer (ATAL) can also be observed in the OMPS/LP dataset. Moreover the effect of the Brewer Dobson Circulation (BDC) can be observed at high altitudes: the BDC velocity at 35 km can be estimated from the time variation of iso-density heights and was found to compare well with BDC velocities evaluated with the water vapor tape recorder technique as well as MERRA model values. Finally, aerosol filaments are clearly visible in OMPS/LP aerosol dataset as they appear as distinct "bubbles" on the OMPS/LP curtain files at periodic intervals in both the Southern and Northern hemispheres. These filaments are a main source of transport from tropical to polar region, and OMPS/LP data can therefore be instrumental in quantifying the rate of this transport. The quality of the OMPS/LP aerosol

  15. Aerosol in the upper layer of earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Morozhenko, A. V.; Vidmachenko, A. P.; Nevodovskii, P. V.

    2013-09-01

    Aerosol layers exist in the upper atmospheres of Venus, Mars, Jupiter, Saturn and the Earth. The reason for their existence may be meteorites, rings, and removal of particles of planetary origin. Observations from 1979 to 1992 showed that the optical thickness of aerosol over the Earth's polar regions changed from tau =0.0002 up to tau =.1 for lambda = 1000 nm. The greatest values of tau were in 1984 and 1992 and they were preceded by a strong volcanic activity of El Chichon (1982) and Pinatubo (1991). We show that the above-mentioned increase in the optical thickness of the stratosphere aerosol can lead to the ozone layer decrease detected in 1970. The stratospheric aerosol nature (real part of refractive index), effective particle size r and changing tau with latitude remain un solved. Among distance methods for the determination of nr and r efficient is the analysis of the phase dependence of the polarization degree. The observational values of the intensity and pol arization degree invisible light are due to optical properties of the surface and optical thickness of the atmosphere, the values of which vary with latitude, longitude and time. Therefore, it is impossible to identify accurately the stratospheric aerosol contribution. When observing in UV at lambda < 300 nm, the ozone layer cuts off the influence of the surface and the Earth's atmosphere to an altitude from 20 to 25 km. In this spectral region some negative factors can take place, namely, the emission of various gases playing depolarizing role, horizontal inhomogeneity of the effective optical thickness of ozone layer, and oriented particles (the polarization plane variation points to their presence).

  16. Modeling the feedback between aerosol and boundary layer processes: a case study in Beijing, China.

    PubMed

    Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu

    2016-02-01

    Rapid development has led to frequent haze in Beijing. With mountains and sea surrounding Beijing, the pollution is found to be influenced by the mountain-plain breeze and sea-land breeze in complex ways. Meanwhile, the presence of aerosols may affect the surface energy balance and impact these boundary layer (BL) processes. The effects of BL processes on aerosol pollution and the feedback between aerosol and BL processes are not yet clearly understood. Thus, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to investigate the possible effects and feedbacks during a haze episode on 23 September 2011. Influenced by the onshore prevailing wind, sea-breeze, and upslope breeze, about 45% of surface particulate matter (PM)2.5 in Beijing are found to be contributed by its neighbor cities through regional transport. In the afternoon, the development of upslope breeze suppresses the growth of BL in Beijing by imposing a relatively low thermal stable layer above the BL, which exacerbates the pollution. Two kinds of feedback during the daytime are revealed as follows: (1) as the aerosols absorb and scatter the solar radiation, the surface net radiation and sensible heat flux are decreased, while BL temperature is increased, resulting in a more stable and shallower BL, which leads to a higher surface PM2.5 concentration in the morning and (2) in the afternoon, as the presence of aerosols increases the BL temperature over plains, the upslope breeze is weakened, and the boundary layer height (BLH) over Beijing is heightened, resulting in the decrease of the surface PM2.5 concentration there. PMID:26490909

  17. Modeling the feedback between aerosol and boundary layer processes: a case study in Beijing, China.

    PubMed

    Miao, Yucong; Liu, Shuhua; Zheng, Yijia; Wang, Shu

    2016-02-01

    Rapid development has led to frequent haze in Beijing. With mountains and sea surrounding Beijing, the pollution is found to be influenced by the mountain-plain breeze and sea-land breeze in complex ways. Meanwhile, the presence of aerosols may affect the surface energy balance and impact these boundary layer (BL) processes. The effects of BL processes on aerosol pollution and the feedback between aerosol and BL processes are not yet clearly understood. Thus, the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) is used to investigate the possible effects and feedbacks during a haze episode on 23 September 2011. Influenced by the onshore prevailing wind, sea-breeze, and upslope breeze, about 45% of surface particulate matter (PM)2.5 in Beijing are found to be contributed by its neighbor cities through regional transport. In the afternoon, the development of upslope breeze suppresses the growth of BL in Beijing by imposing a relatively low thermal stable layer above the BL, which exacerbates the pollution. Two kinds of feedback during the daytime are revealed as follows: (1) as the aerosols absorb and scatter the solar radiation, the surface net radiation and sensible heat flux are decreased, while BL temperature is increased, resulting in a more stable and shallower BL, which leads to a higher surface PM2.5 concentration in the morning and (2) in the afternoon, as the presence of aerosols increases the BL temperature over plains, the upslope breeze is weakened, and the boundary layer height (BLH) over Beijing is heightened, resulting in the decrease of the surface PM2.5 concentration there.

  18. Combined CALIPSO & SAGE II Observations of Asian Tropopause Aerosol Layer

    NASA Astrophysics Data System (ADS)

    Thomason, Larry; Vernier, J.-P.

    2012-07-01

    Observations by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) revealed the presence of an aerosol layer associated with the Asian monsoon anticyclone. While variable in magnitude from season to season, it is apparent in all years since the beginning of the CALIPSO mission in 2006 though partially masked in years by significant volcanic activity. The Stratospheric Aerosol and Gas Experiment (SAGE II) made observations of the upper troposphere and stratosphere from 1984 through the end of its mission in 2005. Aerosol observations by SAGE II in this region of the atmosphere are complicated by cloud presence and past studies had not revealed the presence of this feature. While a cloud detection algorithm had been developed in the past Kent et al. (1997 a, b), it was known that some very thin cloud events were misclassified as aerosol and made the interpretation of observations over southern Asia difficult to interpret. Recently, we have modified the Kent cloud/aerosol separation algorithm by incorporating elements of a technique developed by Mike Pitts et al. for CALIPSO PSC identification. The new method is more effective in the identification of very thin clouds than the Kent method (which has been used as a cloud flag within the data product). Using this method for the post-Pinatubo period (1998-2005), we observe a tropical UTLS aerosol feature that occurs in Northern Hemisphere Summer that stretches from Indonesia over southern Asia toward Africa that is very consistent with the ATAL features found in CALIPSO observations. However, it is not observed in the data set prior to 1998 including periods in the late 1980s and perhaps as early as the late 1970s (using SAGE I observations). In fact, prior to 1998, this region of the atmosphere is observed to be an area of relatively low aerosol loading. In this presentation, we will show the process of identifying the ATAL aerosol layer in the CALIPSO and SAGE data products. While we

  19. Planetary boundary layer height from CALIOP compared to radiosonde over China

    NASA Astrophysics Data System (ADS)

    Zhang, Wanchun; Guo, Jianping; Miao, Yucong; Liu, Huan; Zhang, Yong; Li, Zhengqiang; Zhai, Panmao

    2016-08-01

    Accurate estimation of planetary boundary layer height (PBLH) is key to air quality prediction, weather forecast, and assessment of regional climate change. The PBLH retrieval from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) is expected to complement ground-based measurements due to the broad spatial coverage of satellites. In this study, CALIOP PBLHs are derived from combination of Haar wavelet and maximum variance techniques, and are further validated against PBLHs estimated from ground-based lidar at Beijing and Jinhua. Correlation coefficients between PBLHs from ground- and satellite-based lidars are 0.59 at Beijing and 0.65 at Jinhua. Also, the PBLH climatology from CALIOP and radiosonde are compiled over China during the period from 2011 to 2014. Maximum CALIOP-derived PBLH can be seen in summer as compared to lower values in other seasons. Three matchup scenarios are proposed according to the position of each radiosonde site relative to its closest CALIPSO ground tracks. For each scenario, intercomparisons were performed between CALIOP- and radiosonde-derived PBLHs, and scenario 2 is found to be better than other scenarios using difference as the criteria. In early summer afternoon over 70 % of the total radiosonde sites have PBLH values ranging from 1.6 to 2.0 km. Overall, CALIOP-derived PBLHs are well consistent with radiosonde-derived PBLHs. To our knowledge, this study is the first intercomparison of PBLH on a large scale using the radiosonde network of China, shedding important light on the data quality of initial CALIOP-derived PBLH results.

  20. Comparison of Mixed Layer Heights from Airborne High Spectral Resolution Lidar, Ground-based Measurements, and the WRP-Chem Model during CalNex and CARES

    SciTech Connect

    Scarino, Amy Jo; Obland, Michael; Fast, Jerome D.; Burton, S. P.; Ferrare, R. A.; Hostetler, Chris A.; Berg, Larry K.; Lefer, Barry; Haman, C.; Hair, John; Rogers, Ray; Butler, Carolyn; Cook, A. L.; Harper, David

    2014-06-05

    The California Research at the Nexus of Air Quality and Climate Change (CalNex) and Carbonaceous Aerosol and Radiative Effects Study (CARES) field campaigns during May and June 2010 provided a data set appropriate for studying characteristics of the planetary boundary layer (PBL). The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) was deployed to California onboard the NASA LaRC B-200 aircraft to aid incharacterizing aerosol properties during these two field campaigns. Measurements of aerosol extinction (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 31 flights, many in coordination with other research aircraft and ground sites, constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, as well as the depth and variability of the daytime mixed layer (ML), which is a subset within the PBL. This work illustrates the temporal and spatial variability of the ML in the vicinity of Los Angeles and Sacramento, CA. ML heights derived from HSRL measurements are compared to PBL heights derived from radiosonde profiles, ML heights measured from ceilometers, and simulated PBL heights from the Weather Research and Forecasting Chemistry (WRF-Chem) community model. Comparisons between the HSRL ML heights and the radiosonde profiles in Sacramento result in a correlation coefficient value (R) of 0.93 (root7 mean-square (RMS) difference of 157 m and bias difference (HSRL radiosonde) of 5 m). HSRL ML heights compare well with those from the ceilometer in the LA Basin with an R of 0.89 (RMS difference of 108 m and bias difference (HSRL Ceilometer) of -9.7 m) for distances of up to 30 km between the B-200 flight track and the ceilometer site. Simulated PBL heights from WRF-Chem were compared with those obtained from all flights for each campaign, producing an R of 0.58 (RMS difference of 604 m and a bias difference (WRF-Chem HSRL) of -157 m) for CalNex and 0

  1. Determination of the Mixing Layer Height Over two Sites, Using Pilot Balloons During the MILAGRO Campaign

    NASA Astrophysics Data System (ADS)

    Wohrnschimmel, H.; Alonso, A. L.; Ángeles, F.; Sosa, G.; Varela, J.; Cárdenas, B.

    2007-12-01

    Among the mechanisms that affect air quality there is a variety of meteorological processes. An important process in this context are the changes in the mixing layer height during a day and over the year. The mixing layer height is the portion of the atmosphere close to the surface layer where air pollutants get diluted, without leaving this layer. Therefore, it is important to describe the variations in the height of the mixing layer, i.e. the vertical dilution of air pollution, since this is a process mitigating naturally the impact of emissions. There exist different methods to obtain information on the mixing layer height, among them radio soundings, the application of vertical wind profilers, and launching pilot balloons. In this study, pilot balloons have been used simultaneously over two sites of the Mexico City Metropolitan Area during the MILAGRO campaign in March 2006. The objective was to determine the vertical wind profiles and derive information on the mixing layer height. Daily, four pilot balloons were launched, at 9:00, 12:00, 15:00, and 18:00 hours, over Tenango del Aire (a rural area in the Southeast of Mexico City), and over Ciudad Universitaria, in the Southern metropolitan area. At some occasions, night time measurements have been carried out at 21:00 and 24:00. A variability of the diurnal evolution of the mixing layer was observed along March, which could be related to surface temperature. The diurnal evolution showed a sudden growth of the mixing layer between 9:00 and 12:00 hours. Data intercomparisons were carried out for pilot balloons versus radio soundings during a few days at a third site, Tula, in the North of Mexico City. Both intercomparisons showed that pilot balloons are an effective method to obtain information about the development of the mixing layer.

  2. Stratocumulus cloud thickening beneath layers of absorbing smoke aerosol

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.

    2010-12-01

    Marine stratocumulus cloud properties, and the free-tropospheric environment above them, are examined in NASA A-Train satellite data for cases where smoke from seasonal burning of the West African savannah overlay the persistent southeast Atlantic stratocumulus cloud deck. CALIPSO space-borne lidar observations show that features identified as layers of aerosol occur predominantly between 2 km and 4 km. Layers identified as cloud features occur predominantly below 1.5 km altitude and beneath the layer of elevated smoke aerosol. The diurnal mean shortwave heating rates attributable to the absorption of solar energy in the aerosol layer is nearly 1.5 K d-1 for an aerosol optical thickness value of 1, and increases to 1.8 K d-1 when the smoke resides above clouds owing to the additional component of upward solar radiation reflected by the cloud. As a consequence of this heating, the 700 hPa air temperature above the cloud deck is warmer by approximately 1 K on average for cases where smoke is present above the cloud compared to cases without smoke above cloud. The warmer conditions in the free-troposphere above the cloud during smoke events coincide with cloud liquid water path values that are greater by 20 g m-2 and cloud tops that are lower for overcast conditions compared to periods with low amounts of smoke. The observed thickening and subsidence of the cloud layer are consistent with published results of large-eddy simulations showing that solar absorption by smoke above stratocumulus clouds increases the buoyancy of free-tropospheric air above the temperature inversion capping the boundary layer. Increased buoyancy inhibits the entrainment of dry air through the cloud-top, thereby helping to preserve humidity and cloud cover in the boundary layer. The direct radiative effect of absorbing aerosols residing over a bright cloud deck is a positive radiative forcing (warming) at the top of the atmosphere. However, the greater liquid water path for cases of smoke

  3. What is the Planetary Boundary Layer Height in a Global Perspective?

    NASA Astrophysics Data System (ADS)

    Xie, F.; Syndergaard, S.; von Engeln, A.

    2014-12-01

    The planetary boundary layer (PBL) height is a fundamental parameter characterizing the vertical extent of atmospheric mixing near the surface. It is critical for understanding the PBL process and low cloud evolution and its feedback on the climate system, which remains a key uncertainty in climate modeling. The PBL height is generally defined as the altitude of a transition layer where air temperature or humidity gradient are significant within the lowest 1-5 kilometers above the surface. Numerous thermodynamic parameters, including temperature, humidity (specific/relative humidity) and their derivatives (e.g., potential/virtual potential temperature etc.) have been widely used to define the PBL height. Advances in satellite remote sensing technique allow novel ways to detect the PBL heights from space. Many new parameters are proposed for PBL height detection including GPS radio occultation (RO) measurements (e.g., refractivity, bending angle and dry-temperature) and CALIPSO lidar backscattering measurements (e.g., cloud-top-height). Large discrepancy among various PBL height definitions was revealed from radiosonde analyses, which however are restricted over lands and represent limited horizontal scales of atmospheric conditions. In this talk, we investigate the definition difference in a global perspective by using multi-year high-resolution ERA-interim (1 degree grid with 60 vertical layers) global analysis. Automatic algorithms are applied to compute the PBL heights with various physical parameters (both conventional and GPS RO) at each model grid. The global PBL height seasonal climatology and the difference among the climatologies are derived. Large discrepancy between the thermal-based and humidity-based PBL height definitions is most prominent over tropical and polar regions. Humidity-based PBL heights become problematic over dry regions, especially over high-latitude in winter season. The cloud-top height from CALIPSO is consistent with most physical

  4. Comparative Study of AOD and PM2.5 Relationship with Different Mixing Layer Heights during Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Chu, D. A.; Ferrare, R. A.; Hair, J. W.; Hostetler, C. A.; Holben, B. N.

    2014-12-01

    In this study we will present the results of AOD and PM2.5 relationship during DISCOVER-AQ field experiments in Baltimore-Washington Corridor (BWC) in July 2011, San Joaquin Valley (SJV) in January-February 2013, and Houston Metropolitan Region (HMR) in September 2013). These three domains were selected because of higher concentrations of air pollutants of PM2.5 and ozone under prevailing synoptic systems of humid subtropical summer (BWC and TMR) and Mediterranean winter (SJV), respectively. Airborne and enhanced surface observations of AOD were used in the analysis to serve as the baseline for satellite retrievals. Aerosol extinction profiles differ significantly from region to region. We characterize regional aerosol vertical distribution with respect to mean PBL extinction and near-surface extinction. Diurnal variation of aerosol extinction profiles appears significant between morning and afternoon sampling hours. Linear approximation of AOD in estimating PM2.5 is evaluated with respect to different mixing layer height derivations.

  5. Aerosols optical properties in Titan's Detached Haze Layer

    NASA Astrophysics Data System (ADS)

    Seignovert, Benoit; Rannou, Pascal; Lavvas, Panayotis; West, Robert

    2016-10-01

    Titan's Detached Haze Layer (DHL) was first observed in 1983 by Rages and Pollack during the Voyager 2 is a consistent spherical haze feature surrounding Titan's upper atmosphere and detached from the main haze. Since 2005, the Imaging Science Subsystem (ISS) instrument on board the Cassini mission performs a continuous survey of the Titan's atmosphere and confirmed its persistence at 500 km up to the equinox (2009) before its drop and disappearance in 2012 (West et al. 2011). Previous analyses showed, that this layer corresponds to the transition area between small spherical aerosols and large fractal aggregates and play a key role in the aerosols formation in Titan's atmosphere (Rannou et al. 2000, Lavvas et al. 2009, Cours et al. 2011).In this talk we will present the UV photometric analyses based on radiative transfer inversion to retrieve aerosols particles properties in the DHL (bulk and monomer radius and local density) performed on ISS observations taken from 2005 to 2007.References:- Rages and Pollach, Icarus 55 (1983)- West, et al., Icarus 38 (2011)- Rannou, et al., Icarus 147 (2000)- Lavvas, et al., Icarus 201 (2009)- Cours, et al., ApJ Lett. 741 (2015)

  6. Estimating Planetary Boundary Layer Heights from NOAA Profiler Network Wind Profiler Data

    NASA Technical Reports Server (NTRS)

    Molod, Andrea M.; Salmun, H.; Dempsey, M

    2015-01-01

    An algorithm was developed to estimate planetary boundary layer (PBL) heights from hourly archived wind profiler data from the NOAA Profiler Network (NPN) sites located throughout the central United States. Unlike previous studies, the present algorithm has been applied to a long record of publicly available wind profiler signal backscatter data. Under clear conditions, summertime averaged hourly time series of PBL heights compare well with Richardson-number based estimates at the few NPN stations with hourly temperature measurements. Comparisons with clear sky reanalysis based estimates show that the wind profiler PBL heights are lower by approximately 250-500 m. The geographical distribution of daily maximum PBL heights corresponds well with the expected distribution based on patterns of surface temperature and soil moisture. Wind profiler PBL heights were also estimated under mostly cloudy conditions, and are generally higher than both the Richardson number based and reanalysis PBL heights, resulting in a smaller clear-cloudy condition difference. The algorithm presented here was shown to provide a reliable summertime climatology of daytime hourly PBL heights throughout the central United States.

  7. Height of convective layer in planetary atmospheres with condensable and non-condensable greenhouse substances

    NASA Astrophysics Data System (ADS)

    Makarieva, A. M.; Gorshkov, V. G.; Pujol, T.

    2003-12-01

    Convection reduces greenhouse effect by transporting a certain amount of non-radiative dynamic energy to the upper atmosphere, where this energy dissipates and radiates into space without interaction with greenhouse substances in the lower atmosphere. In this paper we show that the height of the convective layer zc is finite and independent of atmospheric optical thickness τs at large values of the latter. We derive an analytical formula for zc at large values of τs for condensable and non-condensable greenhouse substances. The formula obtained yields reasonable quantitative estimates of the observed height of convective layer on Venus and at low latitudes on Earth, where atmospheric thickness of water vapor is maximum. The dissipative power of dynamic convective processes is limited by the incoming flux of solar radiation. Height of convective layer being finite, values of optical depth at the top of the convective layer and at the mean height of convective energy dissipation increase proportionally to the atmospheric optical thickness, while the contribution of convective energy fluxes to formation of the outgoing flux of thermal radiation proportionally diminishes. As far as optical thickness of condensable greenhouse substances grows exponentially with increasing surface temperature, the obtained results lead to the conclusion that the outgoing thermal radiation into space in the presence of convection tends exponentially to zero with increasing surface temperature, instead of reaching a finite plateau as suggested by earlier radiative-convective studies.

  8. Inter-comparison of lidar methods for obtaining planetary boundary-layer height from a July 2012 monitoring campaign over the Iberian Peninsula in the framework of EARLINET

    NASA Astrophysics Data System (ADS)

    Banks, R. F.; Baldasano, J. M.; Comerón, A.; Sicard, M.

    2013-12-01

    The depth of the planetary boundary-layer (PBL) is defined as the height of the inversion level separating the free troposphere (FT) from the boundary-layer (Stull, 1988). Reliable representation of PBL height is important in applications ranging from climate studies to air quality modeling. Convective turbulent mixing processes are dominant in the mixing layer of the PBL and have a major influence on the growth and transport of atmospheric pollutants. In recent years, lidar (laser radar) has proven to be a useful operational tool for nearly continuous monitoring of the lowest levels of the atmosphere with high spatial (~ 3.75 m) and temporal (< 5 min) resolutions. Four Raman-elastic multi-wavelength lidar stations from EARLINET (European Aerosol Research Lidar Network) conducted a 72-hr campaign of continuous observations over Spain (Barcelona, Granada, Madrid) and Portugal (Evora) in early July 2012. This study systematically exploits 1-min averaged, range-squared-corrected lidar signals (RSCS) from the 532 nm analog reception channel of the instruments. Several methods that have been applied in previous literature to derive PBL height from vertical aerosol backscatter profiles are compared. Most widely used are derivative techniques such as the gradient method (GM), inflection point method (IPM), and logarithm gradient method (LGM) and covariance techniques such as the wavelet covariance transform (WCT) method using a Haar wavelet. The methods function by detecting steep gradients in the aerosol backscatter profile, a proxy for the transition zone between the PBL and FT. It is found that all the methods provide comparable results. However, it is determined that WCT is an optimal method as it is more computationally efficient than the derivative techniques. In summer, PBL heights over the Iberian Peninsula are typically between 1-3 km. In addition, spatial patterns and diurnal variation of the PBL height and an analysis of the meteorological situation over the

  9. Planetary boundary layer heights from GPS radio occultation refractivity and humidity profiles

    NASA Astrophysics Data System (ADS)

    Ao, Chi O.; Waliser, Duane E.; Chan, Steven K.; Li, Jui-Lin; Tian, Baijun; Xie, Feiqin; Mannucci, Anthony J.

    2012-08-01

    The height of the planetary boundary layer (PBL) is an important parameter that relates to the various processes associated with the PBL. In this paper, we use Global Positioning System radio occultation (GPSRO) measurements to derive a global climatology of PBL heights. Utilizing the strength of GPSRO in capturing fine vertical structures, the top of the PBL is defined to be the height at which the vertical gradient of the refractivity or water vapor partial pressure is minimum, corresponding to the height where the refractivity or water vapor pressure changes most rapidly. A "sharpness parameter" is defined that quantifies the applicability of these definitions. The sharpness parameter is largest over the subtropical regions characterized by strong subsidence. When the sharpness parameter is large, the refractivity- and moisture-based heights are shown to converge. We derived global PBL height climatology using three years (Dec. 2006-Nov. 2009) of COSMIC/FORMOSAT-3 measurements and compared with values calculated from ECMWF Reanalysis Interim (ERA-Int). We found that the mean PBL heights from GPSRO shared similar spatial and seasonal variations with ERA-Int; however, GPSRO heights were higher by 500 m. The standard deviation was also higher from GPSRO, especially in the tropics. We present detailed comparisons between GPSRO and ERA-Int over the Pacific Ocean and the Sahara desert and examine the PBL height distributions as well as its annual and diurnal variabilities. These results suggest that the underlying causes of the bias between GPSRO and ERA-Int likely vary from region to region.

  10. The detection of clouds, aerosols and marine atmospheric boundary layer characteristics from simulated GLAS data

    NASA Technical Reports Server (NTRS)

    Palm, Stephen P.; Spinhirne, James D.

    1998-01-01

    Scheduled for launch in 2001 as part of NASA's Earth Observing System (EOS), the Geoscience Laser Altimeter System (GLAS) will provide continuous laser sounding of the earth's atmosphere from space for the first time. From its polar orbit about 600 km above the surface, GLAS will employ a 40 Hz solid state laser operating at 1064 nm to measure topography to an accuracy of 10 cm. Simultaneously, the atmospheric channels (1064 and 532 nm) of GLAS will provide profiles of atmospheric backscatter from 40 km to the ground with 75 meter vertical resolution (Spinhirne and Palm, 1996). These measurements will give scientists an unprecedented global data set on the vertical structure of clouds and aerosols which will greatly aid research efforts aimed at understanding their effects on climate and their role in climate change (Hartman, 1994). To better understand and predict the performance of the GLAS atmospheric channels, a computer model was developed to simulate the type of signal that the instrument would likely produce. The model uses aircraft lidar data and provides realistic simulated GLAS data sets over large areas spanning a wide range of atmospheric conditions. These simulated GLAS datasets are invaluable for designing and testing algorithms for the retrieval of parameters such as cloud and aerosol layer height, optical depth and extinction cross section. This work is currently proceeding and in this paper we will present results of the cloud and aerosol detection algorithm with emphasis on the detection of Marine Atmospheric Boundary Layer (MABL) aerosol. In addition, we use a recently developed technique to ascertain the feasability of estimating MABL moisture and temperature structure from spaceborne systems such as GLAS.

  11. The Importance of the Vertical Location of Aerosol Layers on Convective Storms

    NASA Astrophysics Data System (ADS)

    van den Heever, Susan; Grant, Leah

    2014-05-01

    Enhanced aerosol concentrations appear to influence a number of the aspects of convective storms including the strength of the convective updraft, the intensity of the cold pool, and the microphysical and radiative characteristics of the convective anvil. However, in order for such influences to occur, aerosols need to be effectively ingested by the storm system of interest. The vertical location of an aerosol layer impacting a convective storm may influence how effectively aerosol are ingested by the storm system, and hence the degree to which the ingested aerosol subsequently influence storm microphysical and radiative processes. Furthermore, if the aerosol species impacting the storm are effective at absorbing solar radiation, heating within the aerosol layer enhances atmospheric stability, the level of which will be dictated by where the aerosol layer is located. Enhanced static stability may have negative impacts on the initial development of the convection of interest. Convective storms developing within environments of the same aerosol optical depth may therefore respond differently to aerosol indirect forcing by virtue of where the aerosol layer is vertically located. In this talk, the results of various high-resolution, cloud-resolving simulations will be presented, in which the sensitivity to the vertical location of the aerosol source on the convective development, aerosol ingestion efficiency, and subsequent microphysical and radiative properties are investigated. Microphysical budgets and storm trajectories will form an integral part of the analysis.

  12. Estimation of the mixing layer height over a high altitude site in Central Himalayan region by using Doppler lidar

    SciTech Connect

    Shukla, K. K.; Phanikumar, D. V.; Newsom, Rob K.; Kumar, Niranjan; Ratnam, Venkat; Naja, M.; Singh, Narendra

    2014-03-01

    A Doppler lidar was installed at Manora Peak, Nainital (29.4 N; 79.2 E, 1958 amsl) to estimate mixing layer height for the first time by using vertical velocity variance as basic measurement parameter for the period September-November 2011. Mixing layer height is found to be located ~0.57 +/- 0.1and 0.45 +/- 0.05km AGL during day and nighttime, respectively. The estimation of mixing layer height shows good correlation (R>0.8) between different instruments and with different methods. Our results show that wavelet co-variance transform is a robust method for mixing layer height estimation.

  13. Remote Sensing of Cloud Layer Heights using the Research Scanning Polarimeter

    NASA Astrophysics Data System (ADS)

    Sinclair, K.; van Diedenhoven, B.; Cairns, B.; Yorks, J. E.

    2015-12-01

    Clouds cover roughly two thirds of the globe and act as an important regulator of Earth's radiation budget. Of these, multilayered clouds occur about half of the time and are predominantly two-layered. Changes in cloud top height (CTH) have been predicted by models to have a globally averaged positive feedback, however observational changes in CTH have shown uncertain results. Additional CTH observations are necessary to better and quantify the effect. Improved CTH observations will also allow for improved sub-grid parameterizations in large-scale models and accurate CTH information is important when studying variations in freezing point and cloud microphysics. NASA's airborne Research Scanning Polarimeter (RSP) is able to measure cloud top height using a novel multi-angular contrast approach. RSP scans along the aircraft track and obtains measurements at 152 viewing angles at any aircraft location. The approach presented here aggregates measurements from multiple scans to a single location at cloud altitude using a correlation function designed to identify the location-distinct features in each scan. During NASA's SEAC4RS air campaign, the RSP was mounted on the ER-2 aircraft along with the Cloud Physics Lidar (CPL), which made simultaneous measurements of CTH. The RSP's unique method of determining CTH is presented. The capabilities of using single and combinations of channels within the approach are investigated. A detailed comparison of RSP retrieved CTH's with those of CPL reveal the accuracy of the approach. Results indicate a strong ability for the RSP to accurately identify cloud heights. Interestingly, the analysis reveals an ability for the approach to identify multiple cloud layers in a single scene and estimate the CTH of each layer. Capabilities and limitations of identifying single and multiple cloud layers heights are explored. Special focus is given to sources of error in the method including optically thin clouds, physically thick clouds, multi-layered

  14. Determination of the Schottky barrier height of ferromagnetic contacts to few-layer phosphorene

    SciTech Connect

    Anugrah, Yoska; Robbins, Matthew C.; Koester, Steven J.; Crowell, Paul A.

    2015-03-09

    Phosphorene, the 2D analogue of black phosphorus, is a promising material for studying spin transport due to its low spin-orbit coupling and its ½ nuclear spin, which could allow the study of hyperfine effects. In this work, the properties of permalloy (Py) and cobalt (Co) contacts to few-layer phosphorene are presented. The Schottky barrier height was extracted and determined as a function of gate bias. Flat-band barrier heights, relative to the valence band edge, of 110 meV and 200 meV were determined for Py and Co, respectively. These results are important for future studies of spin transport in phosphorene.

  15. Determination of the Schottky barrier height of ferromagnetic contacts to few-layer phosphorene

    NASA Astrophysics Data System (ADS)

    Anugrah, Yoska; Robbins, Matthew C.; Crowell, Paul A.; Koester, Steven J.

    2015-03-01

    Phosphorene, the 2D analogue of black phosphorus, is a promising material for studying spin transport due to its low spin-orbit coupling and its ½ nuclear spin, which could allow the study of hyperfine effects. In this work, the properties of permalloy (Py) and cobalt (Co) contacts to few-layer phosphorene are presented. The Schottky barrier height was extracted and determined as a function of gate bias. Flat-band barrier heights, relative to the valence band edge, of 110 meV and 200 meV were determined for Py and Co, respectively. These results are important for future studies of spin transport in phosphorene.

  16. 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.

  17. Model representations of aerosol layers transported from North America over the Atlantic Ocean during the Two-Column Aerosol Project

    NASA Astrophysics Data System (ADS)

    Fast, Jerome D.; Berg, Larry K.; Zhang, Kai; Easter, Richard C.; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Liu, Ying; Ortega, Ivan; Sedlacek, Arthur; Shilling, John E.; Shrivastava, Manish; Springston, Stephen R.; Tomlinson, Jason M.; Volkamer, Rainer; Wilson, Jacqueline; Zaveri, Rahul A.; Zelenyuk, Alla

    2016-08-01

    The ability of the Weather Research and Forecasting model with chemistry (WRF-Chem) version 3.7 and the Community Atmosphere Model version 5.3 (CAM5) in simulating profiles of aerosol properties is quantified using extensive in situ and remote sensing measurements from the Two-Column Aerosol Project (TCAP) conducted during July of 2012. TCAP was supported by the U.S. Department of Energy's Atmospheric Radiation Measurement program and was designed to obtain observations within two atmospheric columns; one fixed over Cape Cod, Massachusetts, and the other several hundred kilometers over the ocean. The performance is quantified using most of the available aircraft and surface measurements during July, and 2 days are examined in more detail to identify the processes responsible for the observed aerosol layers. The higher-resolution WRF-Chem model produced more aerosol mass in the free troposphere than the coarser-resolution CAM5 model so that the fraction of aerosol optical thickness above the residual layer from WRF-Chem was more consistent with lidar measurements. We found that the free troposphere layers are likely due to mean vertical motions associated with synoptic-scale convergence that lifts aerosols from the boundary layer. The vertical displacement and the time period associated with upward transport in the troposphere depend on the strength of the synoptic system and whether relatively high boundary layer aerosol concentrations are present where convergence occurs. While a parameterization of subgrid scale convective clouds applied in WRF-Chem modulated the concentrations of aerosols aloft, it did not significantly change the overall altitude and depth of the layers.

  18. Convective boundary layer heights over mountainous terrain – A review of concepts –

    NASA Astrophysics Data System (ADS)

    De Wekker, Stephan; Kossmann, Meinolf

    2015-12-01

    Mountainous terrain exerts an important influence on the Earth's atmosphere and affects atmospheric transport and mixing at a wide range of temporal and spatial scales. The vertical scale of this transport and mixing is determined by the height of the atmospheric boundary layer, which is therefore an important parameter in air pollution studies, weather forecasting, climate modeling, and many other applications. It is recognized that the spatio-temporal structure of the daytime convective boundary layer (CBL) height is strongly modified and more complex in hilly and mountainous terrain compared to flat terrain. While the CBL over flat terrain is mostly dominated by turbulent convection, advection from multi-scale thermally driven flows plays an important role for the CBL evolution over mountainous terrain. However, detailed observations of the CBL structure and understanding of the underlying processes are still limited. Characteristics of CBL heights in mountainous terrain are reviewed for dry, convective conditions. CBLs in valleys and basins, where hazardous accumulation of pollutants is of particular concern, are relatively well-understood compared to CBLs over slopes, ridges, or mountain peaks. Interests in the initiation of shallow and deep convection, and of budgets and long-range transport of air pollutants and trace gases, have triggered some recent studies on terrain induced exchange processes between the CBL and the overlying atmosphere. These studies have helped to gain more insight into CBL structure over complex mountainous terrain, but also show that the universal definition of CBL height over mountains remains an unresolved issue. The review summarizes the progress that has been made in documenting and understanding spatio-temporal behavior of CBL heights in mountainous terrain and concludes with a discussion of open research questions and opportunities for future research.

  19. Convective boundary layer heights over mountainous terrain - A review of concepts -

    NASA Astrophysics Data System (ADS)

    De Wekker, Stephan; Kossmann, Meinolf

    2015-12-01

    Mountainous terrain exerts an important influence on the Earth's atmosphere and affects atmospheric transport and mixing at a wide range of temporal and spatial scales. The vertical scale of this transport and mixing is determined by the height of the atmospheric boundary layer, which is therefore an important parameter in air pollution studies, weather forecasting, climate modeling, and many other applications. It is recognized that the spatio-temporal structure of the daytime convective boundary layer (CBL) height is strongly modified and more complex in hilly and mountainous terrain compared to flat terrain. While the CBL over flat terrain is mostly dominated by turbulent convection, advection from multi-scale thermally driven flows plays an important role for the CBL evolution over mountainous terrain. However, detailed observations of the CBL structure and understanding of the underlying processes are still limited. Characteristics of CBL heights in mountainous terrain are reviewed for dry, convective conditions. CBLs in valleys and basins, where hazardous accumulation of pollutants is of particular concern, are relatively well-understood compared to CBLs over slopes, ridges, or mountain peaks. Interests in the initiation of shallow and deep convection, and of budgets and long-range transport of air pollutants and trace gases, have triggered some recent studies on terrain induced exchange processes between the CBL and the overlying atmosphere. These studies have helped to gain more insight into CBL structure over complex mountainous terrain, but also show that the universal definition of CBL height over mountains remains an unresolved issue. The review summarizes the progress that has been made in documenting and understanding spatio-temporal behavior of CBL heights in mountainous terrain and concludes with a discussion of open research questions and opportunities for future research.

  20. Features of the amplitude-height-frequency characteristics of midlatitude sporadic-E layer

    NASA Astrophysics Data System (ADS)

    Yusupov, Kamil; Akchurin, Adel

    2012-07-01

    At early investigation of an ionosphere the vertical pulse sounding was without separation magnetoionic components and such conditions allowed to observe interferential beatings or polarized fading over frequencies where traces of various magnetoionic component was crossing (overlapping). The beatings in F layer traces are often observed and their origin easily are explain by an interference o - and x-mode whereas in sporadic-E layer traces even observability of beatings of o- and x-modes is in doubt. Absence of experimental evidences of beatings is explain that measurements did not manage to be performed over the necessary time moment because of randomness and a rarity of occurrence high-intensity sporadic-E layers (without properties of scattering on small scale irregularities) and because of high labour input at recording and processing of amplitude-frequency characteristics. The direct observation of interferential beatings became problematic when ionosondes with separations of magnetoionic components appeared. Moreover because of relative vicinity of gyro and background plasma frequencies and also the steep electron profile gradient the beatings in sporadic-E traces should occur between two o-modes because in typical diurnal low-intensity sporadic-E layers (foEs<5MHz) x-mode will be strongly absorbed and the steep gradient on the bottom of sporadic-E layer will strengthen magnetoionic coupling (between o- and x-modes) and lead occurrence of so-called z-mode. The z-mode (extraordinary mode with ordinary polarization) reflected in higher height again takes the form of ordinary mode after passage of height of reflection of ordinary mode and interferes with ordinary mode. However our observations show that beating in sporadic-E traces mostly occur because of interference about o- and x-modes. For detailed research of interference conditions the approximation of width of interference fringes (distance between consecutive minima in interference pattern) as a

  1. Observations of the atmospheric boundary layer height over Abu Dhabi, United Arab Emirates: Investigating boundary layer climatology in arid regions

    NASA Astrophysics Data System (ADS)

    Marzooqi, Mohamed Al; Basha, Ghouse; Ouarda, Taha B. M. J.; Armstrong, Peter; Molini, Annalisa

    2014-05-01

    Strong sensible heat fluxes and deep turbulent mixing - together with marked dustiness and a low substrate water content - represent a characteristic signature in the boundary layer over hot deserts, resulting in "thicker" mixing layers and peculiar optical properties. Beside these main features however, desert ABLs present extremely complex local structures that have been scarcely addressed in the literature, and whose understanding is essential in modeling processes such as the transport of dust and pollutants, and turbulent fluxes of momentum, heat and water vapor in hyper-arid regions. In this study, we analyze a continuous record of observations of the atmospheric boundary layer (ABL) height from a single lens LiDAR ceilometer operated at Masdar Institute Field Station (24.4oN, 54.6o E, Abu Dhabi, United Arab Emirates), starting March 2013. We compare different methods for the estimation of the ABL height from Ceilometer data such as, classic variance-, gradient-, log gradient- and second derivation-methods as well as recently developed techniques such as the Bayesian Method and Wavelet covariance transform. Our goal is to select the most suited technique for describing the climatology of the ABL in desert environments. Comparison of our results with radiosonde observations collected at the nearby airport of Abu Dhabi indicate that the WCT and the Bayesian method are the most suitable tools to accurately identify the ABL height in all weather conditions. These two methods are used for the definition of diurnal and seasonal climatologies of the boundary layer conditional to different atmospheric stability classes.

  2. Marine Boundary Layer Heights over the Eastern North Pacific Based on Measurements from the MAGIC Field Campaign

    NASA Astrophysics Data System (ADS)

    Lewis, E. R.

    2014-12-01

    The MAGIC field campaign, funded and operated by the ARM (Atmospheric Radiation Measurement) Climate Research Facility of the US Department of Energy, occurred between September 2012 and October, 2013 aboard the Horizon Lines cargo container ship Spirit making regular trips between Los Angeles, CA and Honolulu, HI. Along this route, which lies very near the GPCI (GCSS Pacific Cross-section Intercomparison) transect, the predominant cloud regime changes from stratocumulus near the California coast to trade-wind cumulus near Hawaii. The transition between these two regimes is poorly understood and not accurately represented in models. The goal of MAGIC was to acquire statistic of this transition and thus improve its representation in models by making repeated transects through this region and measuring properties of clouds and precipitation, aerosols, radiation, and atmospheric structure. To achieve these goals, the Second ARM Mobile Facility (AMF2) was deployed on the Horizon Spiritas it ran its regular route between Los Angeles and Honolulu. AMF2 consists of three 20-foot SeaTainers and includes three radars, lidars, a ceilometer, microwave radiometers, a total sky imager, disdrometers, and other instruments to measure properties of clouds and precipitation; and other instruments to measure properties of aerosols, radiation, meteorological quantities, and sea surface temperature. Two technicians accompanied the AMF2, and scientists rode the ship as observers. Radiosondes were routinely launched four times daily, and during one round trip in July, 2013, eight radiosondes were launched each day. In total, more than 550 soundings were made. MAGIC made nearly 20 round trips between Los Angeles and Honolulu (and thus nearly 40 excursions through the stratocumulus-to-cumulus transition) and spent 200 days at sea, collecting an unprecedented data set. Boundary layer heights calculated from the radiosonde data using several different algorithms, and those from other

  3. Validation of ASH Optical Depth and Layer Height from IASI using Earlinet Lidar Data

    NASA Astrophysics Data System (ADS)

    Balis, D.; Siomos, N.; Koukouli, M.; Clarisse, L.; Carboni, E.; Ventress, L.; Grainger, R.; Mona, L.; Pappalardo, G.

    2016-06-01

    The 2010 eruptions of the Icelandic volcano Eyjafjallajökull attracted the attention of the public and the scientific community to the vulnerability of the European airspace to volcanic eruptions. The European Space Agency project "Satellite Monitoring of Ash and Sulphur Dioxide for the mitigation of Aviation Hazards", called for the creation of an optimal End-to-End System for Volcanic Ash Plume Monitoring and Prediction. This system is based on improved and dedicated satellite-derived ash plume and sulphur dioxide level assessments, as well as an extensive validation, using among others ground-based measurements (Koukouli et al., 2014). The validation of volcanic ash levels and height extracted from IASI/MetopA is presented in this work with emphasis on the ash plume height and ash optical depth levels. European Aerosol Research Lidar Network [EARLINET] lidar measurements are compared to different satellite estimates for two eruptive episodes. The validation results are extremely promising within the estimated uncertainties of each of the comparative datasets.

  4. Postsunset rise of F layer height in the equatorial region and its relation to the F layer dynamo polarization fields

    SciTech Connect

    Goel, M.K.; Singh, S.S.; Rao, B.C.N. )

    1990-05-01

    The ionosonde data are studied for equatorial station, Thumba, to delineate various features of the evening height rise of F layer. Sharp increase of h'F and h{sub p}F2 is observed in the postsunset period for high solar activity. Seasonal variation is observed in this increase of h'F and it is maximum for equinox months. For summer months, there is a delay of about an hour in the time of occurrence of h'F (peak) as compared to winter and equinox months. This delay is shown to be associated with the delay in sunset times in the conjugate E regions. As for magnetic activity dependence, it is found that this height increase is less pronounced for disturbed days for winter and equinox whereas for summer it is marginally higher over the quiet day values. Further, it is observed that the value of h'F (peak) during disturbed periods is almost at the same value of 350 km for all the three seasons. Thus the seasonal variation of magnetic activity effects appears to be mainly governed by the average seasonal variation for quiet times. The increase in F layer height is due to zonal eastward electric fields developed after sunset which is believed to be due to F region dynamo fields. While the main driving force for these fields is the zonal neutral winds, the development of these fields depend on the ratio of the F region to E region conductivity and the longitudinal gradient in the E region conductivity. Experimental observations of both the neutral winds and ionospheric conductivities are examined for their variation with solar activity, season and magnetic activity as both these factors will contribute for the various observed features of the height rise.

  5. Performance test of the synergetic use of simulated lidar and microwave radiometer observations for mixing-layer height detection

    NASA Astrophysics Data System (ADS)

    Saeed, Umar; Rocadenbosch, Francesc; Crewell, Susanne

    2015-10-01

    There are several instruments and methods to retrieve the atmospheric Mixing Layer Height (MLH). However, none of these instruments or methods can measure the development of the MLH under all atmospheric conditions. For example, aerosol signatures measured by backscatter lidars can be used to determine the MLH but this approach is reasonable only when the atmosphere is well-mixed. Microwave Radiometer (MWR) derived profiles have low vertical resolution and cannot resolve fine structures in the boundary layer, especially, at higher altitudes. Here we propose a method which combines data from a ground-based lidar and a MWR, in simulated as well as real measurements scenarios, to overcome these limitations. The method works by fitting an erf-like transition model function to the section of range-corrected lidar backscatter signal. The section of the lidar backscatter signal for fitting the model function is obtained by incorporating the MWR estimates of MLH along with their uncertainties. The fitting is achieved by using an extended Kalman filter (EKF). The proposed approach, by exploiting the synergy between the two instruments, enables to detect MLH with original vertical and temporal resolutions. Test cases combining simulated data for a co-located lidar-ceilometer and a MWR are presented. The simulated data is obtained from the Dutch Atmospheric Large Eddy Simulation (DALES) model for boundary layer studies. Doppler wind lidar along with radiosondes (whenever available) data is used to assess the quality of the synergetic MLH estimates. Data from the HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany is used to test the proposed method.

  6. Understanding the Processes Controlling Aerosol-Cloud Interactions in the Arctic Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Browse, J.; Carslaw, K. S.; Pringle, K.; Mann, G.; Reddington, C.; Brooks, I. M.; Mulcahy, J.; Young, G.; Allan, J. D.; Liu, D.; Trembath, J.; Dean, A.; Yoshioka, M.

    2015-12-01

    Here we use multiple configurations of the UKCA chemistry and aerosol scheme in a global climate model, capable of simulating cloud condensation nuclei (CCN) and cloud droplet number, to understand the processes controlling aerosol-cloud interactions in the marine Arctic boundary layer. Evaluation against an unprecedented number of aerosol and cloud observations made available through the Global Aerosol Synthesis and Science Project (GASSP), International Arctic Systems for Observing the Atmosphere (IASOA) and the 2013 ACCACIA campaign, suggest that Arctic summertime CCN is well represented in the model. Sensitivity studies indicate that DMS derived nucleation events are the primary source of Arctic summertime aerosol increasing mean (median) surface CCN concentrations north of 70N from 21(14) cm-3 to 46(33) cm-3. However, evaluation against observed aerosol size distributions suggests that UKCA overestimates nucleation mode (~10nm) particle concentrations either due to overestimation of boundary layer nucleation rates or underestimation of the Arctic marine boundary layer condensation sink.

  7. A new method for estimating aerosol mass flux in the urban surface layer using LAS technology

    NASA Astrophysics Data System (ADS)

    Yuan, Renmin; Luo, Tao; Sun, Jianning; Liu, Hao; Fu, Yunfei; Wang, Zhien

    2016-04-01

    Atmospheric aerosol greatly influences human health and the natural environment, as well as the weather and climate system. Therefore, atmospheric aerosol has attracted significant attention from society. Despite consistent research efforts, there are still uncertainties in understanding its effects due to poor knowledge about aerosol vertical transport caused by the limited measurement capabilities of aerosol mass vertical transport flux. In this paper, a new method for measuring atmospheric aerosol vertical transport flux is developed based on the similarity theory of surface layer, the theory of light propagation in a turbulent atmosphere, and the observations and studies of the atmospheric equivalent refractive index (AERI). The results show that aerosol mass flux can be linked to the real and imaginary parts of the atmospheric equivalent refractive index structure parameter (AERISP) and the ratio of aerosol mass concentration to the imaginary part of the AERI. The real and imaginary parts of the AERISP can be measured based on the light-propagation theory. The ratio of the aerosol mass concentration to the imaginary part of the AERI can be measured based on the measurements of aerosol mass concentration and visibility. The observational results show that aerosol vertical transport flux varies diurnally and is related to the aerosol spatial distribution. The maximum aerosol flux during the experimental period in Hefei City was 0.017 mg m-2 s-1, and the mean value was 0.004 mg m-2 s-1. The new method offers an effective way to study aerosol vertical transport in complex environments.

  8. “Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites”

    SciTech Connect

    Ferrare, Richard; Turner, David

    2015-01-13

    Project goals; Characterize the aerosol and ice vertical distributions over the ARM NSA site, and in particular to discriminate between elevated aerosol layers and ice clouds in optically thin scattering layers; Characterize the water vapor and aerosol vertical distributions over the ARM Darwin site, how these distributions vary seasonally, and quantify the amount of water vapor and aerosol that is above the boundary layer; Use the high temporal resolution Raman lidar data to examine how aerosol properties vary near clouds; Use the high temporal resolution Raman lidar and Atmospheric Emitted Radiance Interferometer (AERI) data to quantify entrainment in optically thin continental cumulus clouds; and Use the high temporal Raman lidar data to continue to characterize the turbulence within the convective boundary layer and how the turbulence statistics (e.g., variance, skewness) is correlated with larger scale variables predicted by models.

  9. Internal boundary-layer height formulae — A comparison with atmospheric data

    NASA Astrophysics Data System (ADS)

    Walmsley, John L.

    1989-04-01

    The height of the internal boundary layer (IBL) downwind of a step change in surface roughness is computed using formulae of Elliott (1958), Jackson (1976) and Panofsky and Dutton (1984). The results are compared with neutral-stratification atmospheric data extracted from the set of wind-tunnel and atmospheric data summarized by Jackson (1976) as well as neutral-stratification data presented by Peterson et al. (1979) and new data measured at Cherrywood, Ontario. It is found that the Panofsky-Dutton formulation gives the least root-mean-square (RMS) absolute errors for atmospheric applications.

  10. Analysis of modified MYJ and YSU boundary layer schemes in WRF-Chem with respect to simulated boundary layer heights and pollutant concentrations

    NASA Astrophysics Data System (ADS)

    Forkel, Renate; Foreman, Richard; Emeis, Stefan

    2014-05-01

    To improve the performance of boundary layer schemes currently applied within WRF-Chem (Grell et al., 2005), the Mellor-Yamada-Janjic (MYJ) model (Mellor and Yamada 1982) and the Yonsei University (YSU) PBL scheme (Hong et al. 2006) have been updated using data from a 100 m high offshore measurement tower called FINO1. The turbulence intensity in the Mellor-Yamada-Janjic model has been enhanced as described in Foreman and Emeis (2012). An alternative to the exchange coefficient for stable stratification in the YSU scheme is described in Foreman et al. (2014). These modifications to the two schemes have been applied and are compared with the existing schemes. For example, the updated MYJ scheme results in an improved representation of the turbulent kinetic energy throughout the boundary layer as compared with the measurements at FINO1. The modified MYJ and YSU schemes, which have been originally developed for wind energy applications, have been implemented into version 3.5 of the WRF model. Simulations with WRF-Chem were carried out for Europe and the region of Augsburg in order to evaluate the effect of the modified PBL schemes on simulated PBL heights, gas phase pollutant and aerosol concentrations. Foreman, R.J. and S. Emeis, 2012. A method for increasing the turbulent kinetic energy in the Mellor-Yamada-Janjic boundary layer parametrization. Boundary Layer Meteorology 145:329-349. Foreman, R.J. S. Emeis and B. Canadillas, 2014. Stable boundary layer parametrization without eddy viscosity or turbulent kinetic energy equation approaches. Submitted to Boundary Layer Meteorology 2014. Grell, G. A., Peckham, S. E., Schmitz, R., McKeen, S. A., Frost, G., Skamarock,W. C., and Eder, B., 2005. Fully Coupled Online Chemistry within the WRF Model. Atmospheric Environment 39, 6957-6975. Hong S, Noh Y, Dudhia J 2006. Nonlocal boundary layer vertical diffusion in a medium-range forecast model. Mon Wea Rev 124:2322-2339. Mellor GL, Yamada T 1982. Development of a turbulence

  11. Height-dependent transition from 3-D to 2-D turbulence in the hurricane boundary layer

    NASA Astrophysics Data System (ADS)

    Byrne, David; Zhang, Jun A.

    2013-04-01

    Here we show, from in situ aircraft measurements in the hurricane boundary layer, a height-dependent transition of the flow from 3-D to 2-D turbulence. This marks a fundamental change in the energy dynamics of the hurricane boundary layer due to the fact that in 3-D, energy flows downscale from larger to smaller scales, whereas in 2-D, it flows upscale, from smaller to larger scales. These results represent the first measurement of the 2-D upscale energy flux in the atmosphere and also the first to characterize the transition from 3-D to 2-D. It is shown that the large-scale parent vortex may gain energy directly from small scales in tropical cyclones.

  12. Kinetic model for an auroral double layer that spans many gravitational scale heights

    SciTech Connect

    Robertson, Scott

    2014-12-15

    The electrostatic potential profile and the particle densities of a simplified auroral double layer are found using a relaxation method to solve Poisson's equation in one dimension. The electron and ion distribution functions for the ionosphere and magnetosphere are specified at the boundaries, and the particle densities are found from a collisionless kinetic model. The ion distribution function includes the gravitational potential energy; hence, the unperturbed ionospheric plasma has a density gradient. The plasma potential at the upper boundary is given a large negative value to accelerate electrons downward. The solutions for a wide range of dimensionless parameters show that the double layer forms just above a critical altitude that occurs approximately where the ionospheric density has fallen to the magnetospheric density. Below this altitude, the ionospheric ions are gravitationally confined and have the expected scale height for quasineutral plasma in gravity.

  13. Parametrization of Planetary Boundary-Layer Height with Helicity and Verification with Tropical Cyclone Prediction

    NASA Astrophysics Data System (ADS)

    Ma, Lei-Ming; Bao, Xu-Wei

    2016-09-01

    To reduce the discrepancy between simulated and observed tropical cyclones, we consider a new parametrization scheme for planetary boundary-layer (PBL) height based on helicity, intended to provide an improved description of the overall helical structures of the tropical cyclone PBL simulated in a numerical model. This scheme was preliminarily tested in the Yonsei University (YSU) PBL scheme integrated within the National Center for Atmospheric Research Weather Research and Forecasting model. Based on verification of track simulations for seven tropical cyclones that made landfall over China, tropical cyclone Morakot (2009) was selected for further evaluation of the new scheme. Compared with the original scheme based on the Richardson number ( Ri), the new scheme elevated the PBL height associated with intense convection, which is consistent with observation. Importantly, the new scheme improved the numerical simulation of intense rainfall by modulating the PBL environment for convection evolution. Furthermore, the PBL height and 2-m temperature over land at night, which are frequently overestimated by the original YSU scheme, were improved using the new scheme. Because of its effects on PBL structures and convection evolution, the simulation of tropical cyclone Morakot intensity was improved by the new scheme.

  14. Dust devil height and spacing with relation to the martian planetary boundary layer thickness

    NASA Astrophysics Data System (ADS)

    Fenton, Lori K.; Lorenz, Ralph

    2015-11-01

    In most remote and unmonitored places, little is known about the characteristics of daytime turbulent activity. Few processes render the optically transparent atmospheres of Earth and Mars visible; put more plainly, without clever instruments it is difficult to "see the unseen". To address this, we present a pilot study of images of martian dust devils (DDs) testing the hypothesis that DD height and spacing correlates with the thickness of the planetary boundary layer (PBL), h. The survey includes Context Camera (CTX) images from a 580 × 590 km2 area (196-208°E, 30-40°N) in northern Amazonis Planitia, spanning ∼3.6 Mars Years (MY) from Ls = 134.55°, MY 28 (13 November 2006) to Ls = 358.5°, MY 31 (28 July 2013). DD activity follows a repeatable seasonal pattern similar to that found in previous surveys, with a distinct "on" season during local summer, beginning shortly before the northern spring equinox (Ls = 0°) and lasting until just after the northern fall equinox (Ls = 180°). DD heights measured from shadow lengths varied considerably, with median values peaking at local midsummer. Modeled PBL heights, constrained by those measured from radio occultation data, follow a similar seasonal trend, and correlation of the two suggests that the martian PBL thickness is approximately 5 times the median DD height. These results compare favorably to the limited terrestrial data available. DD spacing was measured using nearest neighbor statistics, following the assumption that because convection cell widths have been measured to be ∼1.2 ± 0.2h (Willis, G.E., Deardorff, J.W. [1979]. J. Geophys. Res. 84(C1), 295-302), a preference for DD formation at vertices of convection cells intersections could be used to estimate the PBL height. During local spring and summer, the DD average nearest neighbor (ANN) ranged from ∼1 to 2h, indicating that DD spacing does indeed correlate with PBL height. However, this result is complicated by two factors: (1) convection cell

  15. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary-layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2015-02-01

    Light scattering and absorption properties of atmospheric aerosols are of vital importance for evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to uplift of aerosol from the plains to the Himalayan range, causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, the Ganges Valley Aerosol Experiment (GVAX) was initiated in Nainital from June 2011 to March 2012 with the aim of examining the aerosol properties, source regions, uplift mechanisms and aerosol-radiation-cloud interactions. The present study examines the temporal (diurnal, monthly, seasonal) evolution of scattering (σlayer dynamics (BLD) and long-range transport (LRT) in aerosol evolution via the Atmospheric Radiation Measurement Mobile Facility. The analysis is separated for particles <10 μm and <1 μm in diameter in order to examine the influence of particle size on optical properties. The σsp and σap exhibit a pronounced seasonal variation between the monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during the monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes. The results reveal higher aerosol concentrations at noontime along with an increase in mixing height, suggesting influence from IGP. The locally emitted aerosols present higher wavelength dependence of the absorption in October-March compared to the rather well-mixed and aged transported aerosols. Monsoon rainfall and seasonally changing air masses contribute to the alteration of the

  16. Global model SMF2 of the F2-layer maximum height

    NASA Astrophysics Data System (ADS)

    Shubin, V. N.; Karpachev, A. T.; Telegin, V. A.; Tsybulya, K. G.

    2015-09-01

    A global model SMF2 (Satellite Model of F2 layer) of the F2-layer height was created. For its creation, data from the topside sounding on board the Interkosmos-19 satellite, as well as the data of radio occultation measurements in the CHAMP, GRACE, and COSMIC experiments, were used. Data from a network of ground-based sounding stations were also additionally used. The model covers all solar activity levels, months, hours of local and universal time, longitudes, and latitudes. The model is a median one within the range of magnetic activity values K p< 3+. The spatial-temporal distribution of hmF2 in the new model is described by mutually orthogonal functions for which the attached Legendre polynomials are used. The temporal distribution is described by an expansion into a Fourier series in UT. The input parameters of the model are geographic coordinates, month, and time (UT or LT). The new model agrees well with the international model of the ionosphere IRI in places where there are many ground-based stations, and it more precisely describes the F2-layer height in places where they are absent: over the oceans and at the equator. Under low solar activity, the standard deviation in the SMF2 model does not exceed 14 km for all hours of the day, as compared to 26.6 km in the IRI-2012 model. The mean relative deviation is by approximately a factor of 4 less than that in the IRI model. Under high solar activity, the maximum standard deviations in the SMF2 model reach 25 km; however, in the IRI they are higher by a factor of ~2. The mean relative deviation is by a factor of ~2 less than in the IRI model. Thus, a hmF2 model that is more precise than IRI-2012 was created.

  17. The Asian Tropopause Aerosol Layer Through Satellite and Balloon-Borne Measurements Combined With Modeling Approaches

    NASA Technical Reports Server (NTRS)

    Vernier, J.-P.; Fairlie, T. D.; Natarajan, M.; Wegner, T.; Baker, N.; Crawford, J.; Moore, J.; Deshler, T.; Gadhavi, H.; Jayaraman, A.; Pandit, A.; Raj, A.; Kumar, H.; Kumar, S.; Singh, A.; Vignelles, D.; Stenchikov, G.; Wiehold, F.; Bian, J.

    2016-01-01

    The Asian Tropopause Aerosol Layer-ATAL is a confined area of enhanced aerosol associated Summer Asia Monsoon spanning from the E. Med Sea to W. China. It essentially extends from top of convective outflow over much of SE Asia Existence recognize through CALIPSO observations.

  18. Complex measurements of aerosol and ion characteristics in the atmospheric boundary layer

    NASA Astrophysics Data System (ADS)

    Kikas, Iu. E.; Kolomiets, S. M.; Kornienko, V. I.; Mirme, A. A.; Sal'm, Ia. I.; Sergeev, I. Ia.; Tammet, Kh. F.

    Results of a comprehensive study of the characteristics of atmospheric ions and aerosols in the boundary layer during the summer season are reported. A study is also made of the kinetics of aerosol formation under conditions of high artificial ionization of the air by alpha and UV radiation. A high degree of correlation is shown to exist between atmospheric concentrations of medium ions and fine (less than 0.01 micron) aerosol. The results obtained support the radiation-chemical mechanism of aerosol formation.

  19. Lidar observations of the Pinatubo aerosol layer at Thule, Greenland

    SciTech Connect

    Di Girolamo, P.; Cacciani, M.; Sarra, A. di; Fiocco, G.; Fua, D. )

    1994-06-22

    This paper summarizes lidar measurements from Thule Greenland made during EASOE. The lidar was able to track aerosols, primarily of volcanic origin, through the winter. Above 18 km the aerosol content was strongly dependent upon the location of the vortex, and did not show a substantial increase until the vortex broke up.

  20. Determination of Planetary Boundary Layer Heights on Short Spatial and Temporal Scales from Surface and Airborne Vertical Profilers during DISCOVER-AQ

    NASA Astrophysics Data System (ADS)

    Delgado, R.; Berkoff, T.; Compton, J. S.; St Pé, A.; Baker, B.; Hoff, R. M.; Martins, D. K.; Thompson, A. M.; Yang, E.; Christopher, S. A.; Joseph, E.; Tzortziou, M.; Lolli, S.; Landry, L.; Woodman, M.; Ferrare, R. A.; Hostetler, C. A.

    2011-12-01

    The National Research Council [2009] identified lower troposphere profiling of trace gases, aerosol and thermodynamic quantities as a cross-cutting need for air quality, weather, climate, energy and other national priority economic areas. A critical parameter in determining air pollution concentrations near the ground is the depth through which pollutants are vigorously mixed. The planetary boundary layer height (PBLH) is an important meteorological parameter that affects near-surface atmospheric pollutant concentrations since it determines the volume of air into which pollutants and their precursors are emitted. This height is also important in determining the relationship between column measures of gases and aerosols and the concentration measured at the surface, since pollutants are frequently contained within the PBL. Determining the mixing in the PBL was one goal of a study of the spatial and diurnal variations of the PBLH over Maryland for July 2011, during NASA's Earth Venture mission DISCOVER-AQ. The PBLHs were obtained from elastic lidars (surface and airborne) and wind profiler observations by determining the convective mixed layer using the covariance wavelet technique (CWT) and comparing it to the virtual potential temperature measurements from soundings. This July, a total of 16 ozone episode days (National Ambient Air Quality Standard 8 hour ozone concentrations greater than 75 ppb) occurred. The relationship between PBLH and surface ozone concentrations was evaluated against ventilation coefficients (product of the PBLH times the surface wind speed) and PBL growth rates during ozone episode and non-episode days. The temporal and spatial distribution of the PBLH in Maryland was modeled with the Weather Research and Forecasting (WRF) model to characterize the role of shoreline circulation and thermally-induced boundary layers on locations along the Chesapeake Bay. National Research Council (2009), Observing Weather and Climate from the Ground Up: A

  1. Exploiting the structure of MWR-derived temperature profile for stable boundary-layer height estimation

    NASA Astrophysics Data System (ADS)

    Saeed, Umar; Rocadenbosch, Francesc

    2015-10-01

    A method for the estimation of Stable Boundary Layer Height (SBLH) using curvature of the potential temperature profiles retrieved by a Microwave Radiometer (MWR) is presented. The vertical resolution of the MWR-derived temperature profile decreases with the height. A spline interpolation is carried-out to obtain a uniformly discretized temperature profile. The curvature parameter is calculated from the first and second order derivatives of the interpolated potential temperature profile. The first minima of the curvature parameter signifies the point where the temperature profile starts changing from the stable to the residual conditions. The performance of the method is analyzed by comparing it against physically idealized models of the stable boundary-layer temperature profile available in the literature. There are five models which include stable-mixed, mixed-linear, linear, polynomial and exponential. For a given temperature profile these five models are fitted using the non-linear least-squares approach. The best fitting model is chosen as the one which fits with the minimum root-mean-square error. Comparison of the SBLH estimates from curvature-based method with the physically idealized models shows that the method works qualitatively and quantitatively well with lower variation. Potential application of this approach is the situation where given temperature profiles are significantly deviant from the idealized models. The method is applied to data from a Humidity-and-Temperature Profiler (HATPRO) MWR collected during the HD(CP)2 Observational Prototype Experiment (HOPE) campaign at Jülich, Germany. Radiosonde data, whenever available, is used as the ground-truth.

  2. Effect of stratospheric aerosol layers on the TOMS/SBUV ozone retrieval

    NASA Technical Reports Server (NTRS)

    Torres, O.; Ahmad, Zia; Pan, L.; Herman, J. R.; Bhartia, P. K.; Mcpeters, R.

    1994-01-01

    An evaluation of the optical effects of stratospheric aerosol layers on total ozone retrieval from space by the TOMS/SBUV type instruments is presented here. Using the Dave radiative transfer model we estimate the magnitude of the errors in the retrieved ozone when polar stratospheric clouds (PSC's) or volcanic aerosol layers interfere with the measurements. The largest errors are produced by optically thick water ice PSC's. Results of simulation experiments on the effect of the Pinatubo aerosol cloud on the Nimbus-7 and Meteor-3 TOMS products are presented.

  3. Air pollution of Moscow by the carbon monoxide and aerosols, boundary layer parameters and estimation of the CO sources intensity.

    NASA Astrophysics Data System (ADS)

    Rakitin, V.; Fokeeva, E.; Kuznetsov, R.; Emilenko, A.; Kopeikin, V.

    2009-04-01

    The results of measurements of the carbon monoxide total content, the soot and submicron aerosols content are given for the period 2005-2008 over Moscow. Two identical grating spectrometers of medium resolution (0,2sm-1) are used with appropriate solar tracking systems, one of which is located outside the city at Zvenigorod Scientific Station (ZSS 56oN, 38oE, 60km West from Moscow in the rural zone) and the other one is inside a city center. This method makes possible to determine the characteristics of anthropogenic pollution, urban part of the CO content. Some simultaneously measurements of aerosols content, the CO column and CO background concentrations in Moscow, autumn 2007 are presented. Nephelometer and quartz filters for soot sampling were used for aerosols measurements. Correlations coefficients between aerosols, CO background concentration and urban part of the CO content were obtained. Permanent sounding of boundary layer was carried out using acoustic locator (SODAR) LATAN-3. Applications of SODAR data (profile of wind speed and inversion height) makes possible to forecast of air pollution situations in megacities area. We obtained the correlation coefficients for the urban part of the CO content with the wind speed for cold and warm seasons. Analysis results of measurements demonstrated preeminent influence of the wind in certain boundary layer (up to 500m) upon the CO extension. The intensity of CO sources in Moscow was estimated. The systematization of CO diurnal variations for different meteorological conditions was performed. Comparing our results with the results of the earlier measurements period (1993-2005), we found out that the urban part of the CO content in the surface air layer over the city did not increase in spite of more than tripled number of motor-vehicles in Moscow. So using the applications of this spectroscopic method we can obtain the air pollution trend from the averaged air pollution measured values.

  4. Secondary Aerosol Formation in the planetary boundary layer observed by aerosol mass spectrometry on a Zeppelin NT

    NASA Astrophysics Data System (ADS)

    Rubach, Florian; Trimborn, Achim; Mentel, Thomas; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL). In combination with the high scientific payload of more than 1 ton, the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due its lifetime of up to several days secondaray aerosol at a certain location can result from local production or from transport processes. For aerosol measurements on a Zeppelin, a High-Resolution Time-of-Flight Aerosol Mass spectrometer (DeCarlo et al, 2006) was adapted to the requirements posed by an airborne platform. A weight reduction of over 20 % compared to the commercial instrument was achieved, while space occupation and footprint were each reduced by over 25 %. Within the PEGASOS project, the instrument was part of 10 measurement flight days over the course of seven weeks. Three flights were starting from Rotterdam, NL, seven flights were starting from Ozzano in the Po Valley, IT. Flight patterns included vertical profiles to study the dynamics of the PBL and cross sections through regions of interest to shed light on local production and transport processes. Analysis of data from transects between the Apennin and San Pietro Capofiume in terms of "residence time of air masses in the Po valley" indicates that aerosol nitrate has only local sources while aerosol sulfate is dominated by transport. The organic aerosol component has significant contributions of both processes. The local prodcution yields are commensurable with imultaneously observed precursor concentrations and oxidant levels. The PEGASOS project is funded by the European Commission under the Framework Programme 7 (FP7-ENV-2010-265148). DeCarlo, P.F. et al (2006), Anal. Chem., 78, 8281-8289.

  5. Aerosol-cloud-precipitation interactions in the trade wind boundary layer

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil

    This dissertation includes an overview of aerosol, cloud, and precipitation properties associated with shallow marine cumulus clouds observed during the Barbados Aerosol Cloud Experiment (BACEX, March-April 2010) and a discussion of their interactions. The principal observing platform for the experiment was the Cooperative Institute for Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft that was equipped with aerosol, cloud, and precipitation probes, standard meteorological instruments, and a up-looking cloud radar. The temporal variations and vertical distributions of aerosols observed on the 15 flights show a wide range of aerosol conditions that include the most intense African dust event observed at the Barbados surface site during all of 2010. An average CCN varied from 50 cm-3 to 800 cm -3 at super-saturation of 0.6 %, for example. The 10-day backward trajectories show that three distinctive air masses (originality of air mass as well as the vertical structure) dominate over the Eastern Caribbean (e.g., typical maritime air mass, Saharan Air Layer (SAL), Middle latitude dry air) with characteristic aerosol vertical structures. Many clouds in various phases of growth during BACEX are sampled. The maximum cloud depth observed is about less than 3 km and in most of the clouds is less than 1 km. Two types of precipitation features were observed for the shallow marine cumulus clouds with different impacts on boundary layer. In one, precipitation shafts are observed to emanate from the cloud base with evaporation in the sub-cloud layer (stabilize the sub-cloud layer). In the other, precipitation shafts emanate mainly near the cloud top on the downshear side of the cloud and evaporate in the cloud layer, leading to destabilizing the cloud layer and providing moisture to the layer. Only 42-44 % of clouds sampled were purely non-precipitating throughout the clouds; the remainder of the clouds showed precipitation somewhere in the cloud

  6. Empirical relationships between soil moisture, albedo, and the planetary boundary layer height: a two-layer bucket model approach

    NASA Astrophysics Data System (ADS)

    Sanchez-Mejia, Z. M.; Papuga, S. A.

    2013-12-01

    In semiarid regions, where water resources are limited and precipitation dynamics are changing, understanding land surface-atmosphere interactions that regulate the coupled soil moisture-precipitation system is key for resource management and planning. We present a modeling approach to study soil moisture and albedo controls on planetary boundary layer height (PBLh). We used data from the Santa Rita Creosote Ameriflux site and Tucson Airport atmospheric sounding to generate empirical relationships between soil moisture, albedo and PBLh. We developed empirical relationships and show that at least 50% of the variation in PBLh can be explained by soil moisture and albedo. Then, we used a stochastically driven two-layer bucket model of soil moisture dynamics and our empirical relationships to model PBLh. We explored soil moisture dynamics under three different mean annual precipitation regimes: current, increase, and decrease, to evaluate at the influence on soil moisture on land surface-atmospheric processes. While our precipitation regimes are simple, they represent future precipitation regimes that can influence the two soil layers in our conceptual framework. For instance, an increase in annual precipitation, could impact on deep soil moisture and atmospheric processes if precipitation events remain intense. We observed that the response of soil moisture, albedo, and the PBLh will depend not only on changes in annual precipitation, but also on the frequency and intensity of this change. We argue that because albedo and soil moisture data are readily available at multiple temporal and spatial scales, developing empirical relationships that can be used in land surface - atmosphere applications are of great value.

  7. Fully Automated Detection of Cloud and Aerosol Layers in the CALIPSO Lidar Measurements

    NASA Technical Reports Server (NTRS)

    Vaughan, Mark A.; Powell, Kathleen A.; Kuehn, Ralph E.; Young, Stuart A.; Winker, David M.; Hostetler, Chris A.; Hunt, William H.; Liu, Zhaoyan; McGill, Matthew J.; Getzewich, Brian J.

    2009-01-01

    Accurate knowledge of the vertical and horizontal extent of clouds and aerosols in the earth s atmosphere is critical in assessing the planet s radiation budget and for advancing human understanding of climate change issues. To retrieve this fundamental information from the elastic backscatter lidar data acquired during the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, a selective, iterated boundary location (SIBYL) algorithm has been developed and deployed. SIBYL accomplishes its goals by integrating an adaptive context-sensitive profile scanner into an iterated multiresolution spatial averaging scheme. This paper provides an in-depth overview of the architecture and performance of the SIBYL algorithm. It begins with a brief review of the theory of target detection in noise-contaminated signals, and an enumeration of the practical constraints levied on the retrieval scheme by the design of the lidar hardware, the geometry of a space-based remote sensing platform, and the spatial variability of the measurement targets. Detailed descriptions are then provided for both the adaptive threshold algorithm used to detect features of interest within individual lidar profiles and the fully automated multiresolution averaging engine within which this profile scanner functions. The resulting fusion of profile scanner and averaging engine is specifically designed to optimize the trade-offs between the widely varying signal-to-noise ratio of the measurements and the disparate spatial resolutions of the detection targets. Throughout the paper, specific algorithm performance details are illustrated using examples drawn from the existing CALIPSO dataset. Overall performance is established by comparisons to existing layer height distributions obtained by other airborne and space-based lidars.

  8. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  9. Mixing layer height and its implications for air pollution over Beijing, China

    NASA Astrophysics Data System (ADS)

    Tang, Guiqian; Zhang, Jinqiang; Zhu, Xiaowan; Song, Tao; Münkel, Christoph; Hu, Bo; Schäfer, Klaus; Liu, Zirui; Zhang, Junke; Wang, Lili; Xin, Jinyuan; Suppan, Peter; Wang, Yuesi

    2016-03-01

    The mixing layer is an important meteorological factor that affects air pollution. In this study, the atmospheric mixing layer height (MLH) was observed in Beijing from July 2009 to December 2012 using a ceilometer. By comparison with radiosonde data, we found that the ceilometer underestimates the MLH under conditions of neutral stratification caused by strong winds, whereas it overestimates the MLH when sand-dust is crossing. Using meteorological, PM2.5, and PM10 observational data, we screened the observed MLH automatically; the ceilometer observations were fairly consistent with the radiosondes, with a correlation coefficient greater than 0.9. Further analysis indicated that the MLH is low in autumn and winter and high in spring and summer in Beijing. There is a significant correlation between the sensible heat flux and MLH, and the diurnal cycle of the MLH in summer is also affected by the circulation of mountainous plain winds. Using visibility as an index to classify the degree of air pollution, we found that the variation in the sensible heat and buoyancy term in turbulent kinetic energy (TKE) is insignificant when visibility decreases from 10 to 5 km, but the reduction of shear term in TKE is near 70 %. When visibility decreases from 5 to 1 km, the variation of the shear term in TKE is insignificant, but the decrease in the sensible heat and buoyancy term in TKE is approximately 60 %. Although the correlation between the daily variation of the MLH and visibility is very poor, the correlation between them is significantly enhanced when the relative humidity increases beyond 80 %. This indicates that humidity-related physicochemical processes is the primary source of atmospheric particles under heavy pollution and that the dissipation of atmospheric particles mainly depends on the MLH. The presented results of the atmospheric mixing layer provide useful empirical information for improving meteorological and atmospheric chemistry models and the forecasting

  10. 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.; Dentener, Frank; Diehl, Thomas; Easter, Richard; Ghan, Steven; Gimoux, Paul; Gong, Sunling; Horowitz, Larry W.; Iversen, Trond; Kirkevag, Alf; Koch, Dorothy; Krol, Maarten; Myhre, Gunnar; Stier, Philip; Takemura, Toshihiko

    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.

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

    SciTech Connect

    Koffi, Brigitte; Schultz, Michael; Breon, Francois-Marie; Griesfeller, Jan; Winker, D.; Balkanski, Y.; Bauer, Susanne E.; Berntsen, T.; Chin, Mian; Collins, William D.; Dentener, Frank; Diehl, Thomas; Easter, Richard C.; Ghan, Steven J.; Ginoux, P.; Gong, S.; Horowitz, L.; Iversen, T.; Kirkevag, A.; Koch, Dorothy; Krol, Maarten; Myhre, G.; Stier, P.; Takemura, T.

    2012-05-19

    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{sub a}) 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{sub a} 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{sub a} than observed by CALIOP, whereas over the African and Chinese dust source regions, Z{sub a} is underestimated during Northern Hemisphere Spring and Summer. The positive model bias in Z{sub a} 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.

  12. The Effect of Backward-Facing Step Height on Instability Growth and Breakdown in Swept Wing Boundary-Layer Transition

    NASA Technical Reports Server (NTRS)

    Eppink, Jenna L.; Wlezien, Richard W.; King, Rudolph A.; Choudhari, Meelan

    2015-01-01

    A low-speed experiment was performed on a swept at plate model with an imposed pressure gradient to determine the effect of a backward-facing step on transition in a stationary-cross flow dominated flow. Detailed hot-wire boundary-layer measurements were performed for three backward-facing step heights of approximately 36, 45, and 49% of the boundary-layer thickness at the step. These step heights correspond to a subcritical, nearly-critical, and critical case. Three leading-edge roughness configurations were tested to determine the effect of stationary-cross flow amplitude on transition. The step caused a local increase in amplitude of the stationary cross flow for the two larger step height cases, but farther downstream the amplitude decreased and remained below the baseline amplitude. The smallest step caused a slight local decrease in amplitude of the primary stationary cross flow mode, but the amplitude collapsed back to the baseline case far downstream of the step. The effect of the step on the amplitude of the primary cross flow mode increased with step height, however, the stationary cross flow amplitudes remained low and thus, stationary cross flow was not solely responsible for transition. Unsteady disturbances were present downstream of the step for all three step heights, and the amplitudes increased with increasing step height. The only exception is that the lower frequency (traveling crossflow-like) disturbance was not present in the lowest step height case. Positive and negative spikes in instantaneous velocity began to occur for the two larger step height cases and then grew in number and amplitude downstream of reattachment, eventually leading to transition. The number and amplitude of spikes varied depending on the step height and cross flow amplitude. Despite the low amplitude of the disturbances in the intermediate step height case, breakdown began to occur intermittently and the flow underwent a long transition region.

  13. The study of aerosol and ozone measurements in lower boundary layer with UAV helicopter platform

    NASA Astrophysics Data System (ADS)

    Lin, Po-hsiung; Chen, Wen-nai

    2013-04-01

    This study describes the aerosol and ozone measurement in the lower atmospheric boundary layer of highly polluted region at Kao-hsiung, Taiwan with a small unmanned aerial vehicle (UAV) helicopter platform. This UAV helicopter, modified from Gaui-X7 electronic-power model helicopter with autopilot AHRS (Altitude-Head-Reference System) kit, has fast climb speed up to 700 m height and keeps stable status for atmospheric measurements in five-minute fly leg. Several quick-replaced battery packages are ready on ground for field intensive observation. The payload rack under this UAV helicopter carries a micro-Aethalometer (black carbon concentration), ozone meter, temperature-humidity sensor, barometer and a time-lapse digital camera. The field measurement site closes to Linyuan Petrochemical Industrial Park, where is one of the heavy polluted regions in Taiwan. Balloon-borne Vaisala RS-92 radiosonde and CL31 Lidar Ceilometer are used to provide the background of the atmosphere at the same time. More data analysis measured by UAV helicopter and its potential application will be discussed.

  14. The persistently variable "background" stratospheric aerosol layer and global climate change.

    PubMed

    Solomon, S; Daniel, J S; Neely, R R; Vernier, J-P; Dutton, E G; Thomason, L W

    2011-08-12

    Recent measurements demonstrate that the "background" stratospheric aerosol layer is persistently variable rather than constant, even in the absence of major volcanic eruptions. Several independent data sets show that stratospheric aerosols have increased in abundance since 2000. Near-global satellite aerosol data imply a negative radiative forcing due to stratospheric aerosol changes over this period of about -0.1 watt per square meter, reducing the recent global warming that would otherwise have occurred. Observations from earlier periods are limited but suggest an additional negative radiative forcing of about -0.1 watt per square meter from 1960 to 1990. Climate model projections neglecting these changes would continue to overestimate the radiative forcing and global warming in coming decades if these aerosols remain present at current values or increase.

  15. Radiative Impact of Observed and Simulated Aerosol Layers Over the East Coast of North America

    NASA Astrophysics Data System (ADS)

    Berg, L. K.; Fast, J. D.; Burton, S. P.; Chand, D.; Comstock, J. M.; Ferrare, R. A.; Hair, J. W.; Hostetler, C. A.; Hubbe, J. M.; Kassianov, E.; Rogers, R. R.; Sedlacek, A. J., III; Shilling, J. E.; Tomlinson, J. M.; Wilson, J. M.; Zelenyuk, A.

    2014-12-01

    The vertical distribution of particles in the atmospheric column can have a large impact on the radiative forcing and cloud microphysics. A recent climatology constructed using data collected by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) suggests elevated layers of aerosol are quite common near the North American east coast during both winter and summer. The Two-Column Aerosol Project (TCAP), conducted from June 2012 through June 2013, was a unique study utilizing both in situ and remotely sensed measurements designed to provide a comprehensive data set that can be used to investigate science questions related to aerosol radiative forcing and the vertical distribution of aerosol. The study sampled the atmosphere at a number of altitudes within two atmospheric columns; one located near the coast of North America (over Cape Cod, MA) and a second over the Atlantic Ocean several hundred kilometers from the coast. TCAP included the yearlong deployment of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF) located at the base of the Cape Cod column, as well as summer and winter aircraft intensive observation periods (IOPs) using the ARM Aerial Facility. One important finding from the TCAP summer IOP is the relatively common occurrence (during four of the six nearly cloud-free flights) of elevated aerosol layers in both the Cape Cod and maritime columns that were detected using the nadir pointing second-generation NASA Langley Research Center High-Spectral Resolution Lidar (HSRL-2). These elevated layers contributed up to 60% of the total observed aerosol optical depth (AOD). Many of these layers were also intercepted by the aircraft configured for in situ sampling, and the aerosol in the layers was found to have increased amounts of biomass burning material and nitrate compared to aerosol found near the surface. Both the in situ and remote sensing observations have been compared to

  16. Characterizing interactions between aerosols and cloud droplets in marine boundary layer clouds

    NASA Astrophysics Data System (ADS)

    Andersen, Hendrik; Cermak, Jan

    2016-04-01

    This contribution presents a method to characterize the nonlinearities of interactions between aerosols and cloud droplets in marine boundary layer clouds based on global MODIS observations. Clouds play a crucial role in the climate system as their radiative properties and precipitation patterns significantly impact the Earth's energy balance. Cloud properties are determined by environmental conditions, as cloud formation requires the availability of water vapour ("precipitable water") and condensation nuclei in sufficiently saturated conditions. The ways in which aerosols as condensation nuclei in particular influence the optical, micro- and macrophysical properties of clouds are one of the largest remaining uncertainties in climate-change research. In particular, cloud droplet size is believed to be impacted, and thereby cloud reflectivity, lifetime, and precipitation susceptibility. However, the connection between aerosols and cloud droplets is nonlinear, due to various factors and processes. The impact of aerosols on cloud properties is thought to be strongest with low aerosol loadings, whereas it saturates with high aerosol loadings. To gain understanding of the processes that govern low cloud water properties in order to increase accuracy of climate models and predictions of future changes in the climate system is thus of great importance. In this study, global Terra MODIS L3 data sets are used to characterize the nonlinearities of the interactions between aerosols and cloud droplets in marine boundary layer clouds. MODIS observations are binned in classes of aerosol loading to identify at what loading aerosol impact on cloud droplets is the strongest and at which loading it saturates. Results are connected to ERA-Interim and MACC data sets to identify connections of detected patterns to meteorology and aerosol species.

  17. Ceilometer evaluation of the eastern Mediterranean summer boundary layer height - first study of two Israeli sites

    NASA Astrophysics Data System (ADS)

    Uzan, Leenes; Egert, Smadar; Alpert, Pinhas

    2016-09-01

    Active remote-sensing instruments, such as ceilometers, have been shown to be potentially useful for the investigation of the behavior of the atmospheric mixing layer height (MLH). For the first time ever, high-resolution measurements of backscatter intensity, taken from two CL31 ceilometers situated inland and onshore of Israel, have enabled evaluation of the mean diurnal cycle of the MLH in the eastern Mediterranean region. Although the Israeli summer synoptic conditions are considered to be quite stable, results for the summer season (July-August 2014) showed the inland MLH to be about 200 m higher than the MLH at the onshore site, situated only 7.5 km away. The prevailing influence of the sea breeze front (SBF), as it progresses inland, is presented by the ceilometer plots. Complementing results were found between the radiosonde profiles and the adjacent ceilometer at the inland site of Beit Dagan. In contrast to the expected regularity of clear skies during the Israeli summer, the ceilometers revealed significant cloud cover throughout the day, with higher presence onshore. Assessment of cloud thickness in further research would serve to improve the evaluation of the MLH evolution.

  18. Transport and Evolution of Aerosol Above/Below the Boundary Layer in the Western Mediterranean Basin

    NASA Astrophysics Data System (ADS)

    Roberts, G. C.; Corrigan, C.; Ritchie, J.; Pont, V.; Claeys, M.; Sciare, J.; Mallet, M.; Dulac, F.

    2014-12-01

    The Mediterranean Region has been identified as sensitive to changes in the hydrological cycle, which could affect the water resources for millions of people by the turn of the century. However, prior to recent observations, most climate models have not accounted for the impacts of aerosol in this region. Past airborne studies have shown that aerosol sources from Europe and Africa are often transported throughout the lower troposphere; yet, because of their complex vertical distribution, it is a challenge to capture the variability and quantify the contribution of these sources to the radiative budget and precipitation processes. The PAEROS ChArMEx Mountain Experiment (PACMEx) complemented the regional activities of the ChArMEx/ADRIMED summer 2013 campaign by collecting aerosol data from atop a mountain on the island of Corsica, France in order to assess boundary layer / free troposphere atmospheric processes. In June/July 2013, PACMEx instruments were deployed at 2000 m.asl near the center of Corsica to complement ground-based aerosol observations at 550 m.asl on the northern peninsula, as well as airborne measurements. Comparisons between the peninsula site and the mountain site show similar general trends in aerosol properties; yet, differences in aerosol properties reveal the myriad transport mechanisms over the Mediterranean Basin. Using aerosol physicochemical data coupled with back trajectory analysis, different sources have been identified including Saharan dust transport, residual dust mixed with sea salt, anthropogenic emissions from Western Europe, and a period of biomass burning from Eastern Europe. Each period exhibits distinct signatures in the aerosol related to transport processes above and below the boundary layer. In addition, the total aerosol concentrations at the mountain site revealed a strong diurnal cycling between the atmospheric boundary layer and the free troposphere, which is typical of mountain-top observations. PACMEx was funded by the

  19. Aircraft Observations of Marine Aerosol Properties in the Presence of Boundary Layer Rolls

    NASA Astrophysics Data System (ADS)

    Kapustin, V.; Clarke, A.; Howell, S.; Conley, S.; Faloona, I.; Brekhovskikh, V.; McNaughton, C.

    2008-12-01

    The Hawaii Group for Environmental Aerosol Research deployed a wide range of airborne aerosol instrumentation as part of MILAGRO/INTEX (2006) and PASE (2007) experiments. These were designed to provide rapid information on aerosol composition, state of mixing (internal or external), spectral optical properties (scattering and absorption), the humidity dependence of light scattering - f(RH). The measurements revealed frequently observed presence of numerous periodic structures related both to horizontal convective rolls (HCRs) and Kelvin-Helmholtz instability (KHI). HCRs, commonly formed when some vertical wind shear is present, are significant to the vertical transport of momentum, heat, moisture, and air pollutant including aerosols within the boundary layer. KHIs, occurred in areas of enhanced velocity shear and/or a local minimum of static stability, contribute strongly to the dissipation of large-scale motions into turbulence. This presentation focused on the direct in-situ marine aerosol properties in the presence of BL rolls by providing evidence that the observed variations are caused by rolls. We also studied whether the presence of rolls leads to the enhancement of aerosol fluxes. We have investigated roll structures in diverse MBL settings and have demonstrated that these can play an active role in the redistribution of aerosol, gas and water vapor in the MBL. Depending upon the thermodynamic profiles and the roll size, altitude, temporal duration these rolls can have a marked effect on the exchange of air masses between the buffer layer, the surface mixed layer and the free troposphere. This will lead to changes in the horizontal extinction in these layers relative to regions not influenced by the rolls. Hence, the evolution of aerosol optical properties in the near-surface mixed layer will be affected by rolls and the conditions that stimulate them. These can occur with or without associated cloud features. Some ongoing studies include the following

  20. The Asian Tropopause Aerosol layer through satellite and balloon-borne measurements combined with modelling approaches.

    NASA Astrophysics Data System (ADS)

    Vernier, J. P.; Fairlie, T. D.; Natarajan, M.; Crawford, J. H.; Baker, N. C.; Wegner, T.; Deshler, T.; Gadhavi, H. S.; Kumar, S.; Singh, A. K.; Jayaraman, A.; Raj, A.; Alladi, H.; Ratnam, M. V.; Pandit, A.; Vignelles, D.; Wienhold, F.; Liu, H.; Kumar, S.

    2015-12-01

    The Asian tropopause Aerosol Layer (ATAL) is a seasonal aerosol feature occurring in the Upper Troposphere and Lower Stratosphere (UTLS) above Asia during the Summer Asian Monsoon. Vertically resolved aerosol backscatter profiles from the Cloud-Aerosol Lidar and Infrared Pathfinder satellite Observation (CALIPSO) mission and extinction profiles from the Stratospheric Aerosol and Gas Experiment (SAGE) have been used to infer the spatial and temporal distributions of the ATAL since the late 90's. We found that aerosol optical thickness between 13-18km have increased by a factor of 2-3 over the past 16 years likely related to raising pollution levels in South East Asia occuring during the same period. Modelling studies of the ATAL using WACCAM 3 and GEOS-Chem have provided conflicting information on its origin and a better representation of in-cloud SO2 and aerosol lifetime in GOES-Chem seems to be key to obtain consistent results with the few SO2 measurements available in the UTLS during the Asian Monsoon. In situ measurements of aerosol and trace gases in the UTLS from several balloon campaigns which took place in summer 2014 and 2015 in Asia will be presented and discussed with combined satellite and modelling analysis.

  1. [Characteristics of Winter Atmospheric Mixing Layer Height in Beijing-Tianjin-Hebei Region and Their Relationship with the Atmospheric Pollution].

    PubMed

    Li, Meng; Tang, Gui-qian; Huang, Jun; Liu, Zi-rui; An, Jun-lin; Wang, Yue-si

    2015-06-01

    Atmospheric mixing layer height (MLH) is one of the main factors affecting the atmospheric diffusion and plays an important role in air quality assessment and distribution of the pollutants. Based on the ceilometers data, this paper has made synchronous observation on MLH in Beijing-Tianjin-Hebei region (Beijing, Tianjin, Shijiazhuang and Qinhuangdao) in heavy polluted February 2014 and analyzed the respective overall change and its regional features. Results show that in February 2014,the average of mixing layer height in Qinhuangdao is the highest, up to 865 +/- 268 m, and in Shijiazhuang is the lowest (568 +/- 207 m), Beijing's and Tianjin's are in between, 818 +/- 319 m and 834 +/- 334 m respectively; Combined with the meteorological data, we find that radiation and wind speed are main factors of the mixing layer height; The relationship between the particle concentration and mixing layer height in four sites suggests that mixing layer is less than 800 m, concentration of fine particulate matter in four sites will exceed the national standard (GB 3095-2012, 75 microg x m(-3)). During the period of observation, the proportion of days that mixing layer is less than 800 m in Beijing, Tianjin, Shijiazhuang and Qinhuangdao are 50%, 43%, 80% and 50% respectively. Shijiazhuang though nearly formation contaminant concentration is high, within the atmospheric mixed layer pollutant load is not high. Unfavorable atmospheric diffusion conditions are the main causes of heavy pollution in Shijiazhuang for a long time. The results of the study are of great significance for cognitive Beijing-Tianjin-Hebei area pollution distribution, and can provide a scientific reference for reasonable distribution of regional pollution sources.

  2. Aerosol/Cloud Measurements Using Coherent Wind Doppler Lidars

    NASA Astrophysics Data System (ADS)

    Royer, Philippe; Boquet, Matthieu; Cariou, Jean-Pierre; Sauvage, Laurent; Parmentier, Rémy

    2016-06-01

    The accurate localization and characterization of aerosol and cloud layers is crucial for climate studies (aerosol indirect effect), meteorology (Planetary Boundary Layer PBL height), site monitoring (industrial emissions, mining,…) and natural hazards (thunderstorms, volcanic eruptions). LEOSPHERE has recently developed aerosol/cloud detection and characterization on WINDCUBE long range Coherent Wind Doppler Lidars (CWDL). These new features combine wind and backscatter intensity informations (Carrier-to-Noise Ratio CNR) in order to detect (aerosol/cloud base and top, PBL height) and to characterize atmospheric structures (attenuated backscatter, depolarization ratio). For each aerosol/cloud functionality the method is described, limitations are discussed and examples are given to illustrate the performances.

  3. High Spectral Resolution Lidar (HSRL)-2 Observations of Aerosol Variability and Mixing during Boundary Layer Evolution in Houston

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Scarino, A. J.; Rogers, R. R.; Hostetler, C. A.; Ferrare, R. A.; Sawamura, P.; Berkoff, T.; Harper, D. B.; Cook, A. L.; Saide, P. E.

    2014-12-01

    The NASA Langley airborne multi-wavelength High Spectral Resolution Lidar (HSRL-2) provides the 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. In Houston, HSRL-2 generally observed significant variability with distinct layering: boundary layer, residual layer, and frequent upper layers of smoke transported from the Mississippi Valley. The period from Sep. 11-14 is notable for a large aerosol build-up and persistent layers in the free troposphere. We investigate the aerosol properties and evolution using the vertically resolved HSRL-2 measurements, typing and mixture analysis techniques, and boundary layer detection. Between morning and afternoon overpasses, as the boundary layer grows, many distinctions between the layers are lost as the aerosols become mixed. As the boundary layer collapses overnight, the aerosols are cut off and are observed in a distinct residual layer the following morning. HSRL-2 measurements of the upper smoke layers suggest slightly different properties each day as new smoke enters the region, while the morning boundary layer indicates more similarity in local emissions day-to-day. HSRL-2 intensive variables (indicators of aerosol type) reflect complex yet predictable mixing. We will present the analysis of aerosol mixtures, and explore the WRF-Chem chemical transport model along the HSRL-2

  4. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: An ARM Mobile Facility Deployment

    NASA Technical Reports Server (NTRS)

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; de Szoeke, Simone; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, J. Christine; Mann, Julian A. L.; O'Connor, Ewan J.; Hogan, Robin J.; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palikonda, Rabindra; Albrecht, Bruce; Luke, Ed; Hannay, Cecile; Lin, Yanluan

    2015-01-01

    Capsule: A 21-month deployment to Graciosa Island in the northeastern Atlantic Ocean is providing an unprecedented record of the clouds, aerosols and meteorology in a poorly-sampled remote marine environment The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21 month (April 2009- December 2010) comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1- 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging. The data from at Graciosa are being compared with short-range forecasts made a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a

  5. New evidence of an organic layer on marine aerosols

    NASA Astrophysics Data System (ADS)

    Tervahattu, Heikki; Hartonen, Kari; Kerminen, Veli-Matti; Kupiainen, Kaarle; Aarnio, Päivi; Koskentalo, Tarja; Tuck, Adrian F.; Vaida, Veronica

    2002-04-01

    An extraordinary episode of fine particles (diameter mainly <2.5 μm) occurred in Helsinki, southern Finland, at the end of February 1998. The air masses came from the North Atlantic Ocean and passed over France, Germany, and southern Scandinavia. Particles were collected during the episode as well as before and after it. Uncoated particle samples were adhered to an indium substrate and were studied by a scanning electron microscope (SEM) coupled with an energy dispersive X-ray microanalyzer (EDX). A great proportion of the particles behaved differently than aerosols previously studied by microscopic techniques. The particles (size mainly 0.5-1 μm) did not exhibit solid shape. They were ``bubbling'' or ``pulsating'' continually, enlarging in one part and shrinking in another. Some particles were broken down, especially when the beam of the electron microscope was focused on them. EDX analyses showed that the particles contained much carbon together with oxygen, sulfur, and sodium. Ion analyses by ion chromatography revealed high concentrations of sodium, sulfate, nitrate, and ammonium. The particles were identified as marine sea-salt aerosols, which had accumulated anthropogenic emissions and lost chloride during their flow through continental polluted air. The shape fluctuations and the high carbon content observed by SEM/EDX led to the conclusion that the aerosols were enclosed by an organic membrane. Direct insertion probe/mass spectrometry investigations showed remarkable amounts of fragmented aliphatic hydrocarbons, which were considered as an evidence of a lipid membrane on the surface of the particles. The impact of the posited organic film on the properties of sea-salt particles, as well as on Earth's climate, is discussed.

  6. DUAL ORIGIN OF AEROSOLS IN TITAN'S DETACHED HAZE LAYER

    SciTech Connect

    Cours, T.; Burgalat, J.; Rannou, P.; Rodriguez, S.; Brahic, A.

    2011-11-10

    We have analyzed scattered light profiles from the Cassini Imaging Science Subsystem, taken at the limb and at several large phase angles. We also used results from an occultation observed by Ultraviolet Imaging Spectrograph in the ultraviolet. We found that particles responsible for the scattering in the detached haze have an effective radius around 0.15 {mu}m and the aerosol size distribution follows a power law (exponent about -4.5). We discuss these results along with microphysical constraints and thermal equilibrium of the detached haze, and we conclude that only a strong interaction with atmospheric dynamics can explain such a structure.

  7. Lidar Investigations of Aerosol, Cloud, and Boundary Layer Properties Over the ARM ACRF Sites

    SciTech Connect

    Turner, David D.; Ferrare, Richard

    2015-01-13

    The systematic and routine measurements of aerosol, water vapor, and clouds in the vertical column above the Atmospheric Radiation Measurement (ARM) sites from surface-based remote sensing systems provides a unique and comprehensive data source that can be used to characterize the boundary layer (i.e., the lowest 3 km of the atmosphere) and its evolution. New algorithms have been developed to provide critical datasets from ARM instruments, and these datasets have been used in long-term analyses to better understand the climatology of water vapor and aerosol over Darwin, the turbulent structure of the boundary layer and its statistical properties over Oklahoma, and to better determine the distribution of ice and aerosol particles over northern Alaska.

  8. Application and Limitations of GPS Radio Occultation (GPS-RO) Data for Atmospheric Boundary Layer Height Detection over the Arctic.

    NASA Astrophysics Data System (ADS)

    Ganeshan, M.; Wu, D. L.

    2014-12-01

    Due to recent changes in the Arctic environment, it is important to monitor the atmospheric boundary layer (ABL) properties over the Arctic Ocean, especially to explore the variability in ABL clouds (such as sensitivity and feedback to sea ice loss). For example, radiosonde and satellite observations of the Arctic ABL height (and low-cloud cover) have recently suggested a positive response to sea ice loss during October that may not occur during the melt season (June-September). Owing to its high vertical and spatiotemporal resolution, an independent ABL height detection algorithm using GPS Radio Occultation (GPS-RO) refractivity in the Arctic is explored. Similar GPS-RO algorithms developed previously typically define the level of the most negative moisture gradient as the ABL height. This definition is favorable for subtropical oceans where a stratocumulus-topped ABL is often capped by a layer of sharp moisture lapse rate (coincident with the temperature inversion). The Arctic Ocean is also characterized by stratocumulus cloud cover, however, the specific humidity does not frequently decrease in the ABL capping inversion. The use of GPS-RO refractivity for ABL height retrieval therefore becomes more complex. During winter months (December-February), when the total precipitable water in the troposphere is a minimum, a fairly straightforward algorithm for ABL height retrieval is developed. The applicability and limitations of this method for other seasons (Spring, Summer, Fall) is determined. The seasonal, interannual and spatial variability in the GPS-derived ABL height over the Arctic Ocean, as well as its relation to the underlying surface (ice vs. water), is investigated. The GPS-RO profiles are also explored for the evidence of low-level moisture transport in the cold Arctic environment.

  9. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, B.; Gysel, M.; Rubach, F.; Mentel, T. F.; Goger, B.; Poulain, L.; Schlag, P.; Miettinen, P.; Pajunoja, A.; Virtanen, A.; Bialek, J.; Klein Baltink, H.; Henzing, J. S.; Größ, J.; Gobbi, G. P.; Wiedensohler, A.; Kiendler-Scharr, A.; O'Dowd, C.; Decesari, S.; Facchini, M. C.; Weingartner, E.; Baltensperger, U.

    2015-03-01

    Airborne measurements of the aerosol hygroscopic and optical properties as well as chemical composition were performed in the Netherlands and northern Italy on board of a Zeppelin NT airship during the PEGASOS field campaigns in 2012. The vertical changes in aerosol properties during the development of the mixing layer were studied. Hygroscopic growth factors (GF) at 95% relative humidity were determined using the white-light humidified optical particles spectrometer (WHOPS) for dry diameters of 300 and 500 nm particles. These measurements were supplemented by an aerosol mass spectrometer (AMS) and an aethalometer providing information on the aerosol chemical composition. Several vertical profiles between 100 and 700 m a.g. were flown just after sunrise close to the San Pietro Capofiume ground station in the Po Valley, Italy. During the early morning hours the lowest layer (newly developing mixing layer) contained a high nitrate fraction (20%) which was coupled with enhanced hygroscopic growth. In the layer above (residual layer) small nitrate fractions of ~ 2% were measured as well as low GFs. After full mixing of the layers, typically around noon and with increased temperature, the nitrate fraction decreased to 2% at all altitudes and led to similar hygroscopicity values as found in the residual layer. These distinct vertical and temporal changes underline the importance of airborne campaigns to study aerosol properties during the development of the mixed layer. The aerosol was externally mixed with 22 and 67% of the 500 nm particles in the range GF < 1.1 and GF > 1.5, respectively. Contributors to the non-hygroscopic mode in the observed size range are most likely mineral dust and biological material. Mean hygroscopicity parameters (κ) were 0.34, 0.19 and 0.18 for particles in the newly forming mixing layer, residual layer and fully mixed layer, respectively. These results agree well with those from chemical analysis which found values of κ = 0.27, 0.21 and 0

  10. Aerosol Layering Characterization Near the Gobi Desert by a Double Polarization Lidar System

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Boselli, A.; Sannino, A.; Song, C.; Spinelli, N.; Wang, X.

    2016-06-01

    In order to carry out 4-D (space and time) analysis of the atmospheric aerosol distribution and to make a characterization of their properties and time evolution, a transportable multi-wavelength, Elastic/Raman scanning lidar system with angular scanning capability has been realized. The system uses a diode pumped Nd:YAG laser source, specifically designed for this device, and a receiving systems able to detect elastic signals at 355, 532 and 1064 nm and Raman signals at 386, 407 and 607 nm. It also allows to perform aerosol depolarization measurements at both 355nm and 532nm. A first measurement campaign has been carried out in Dunhuang, North-West of China, in the region of the Gobi desert with the aims to study and characterize desert dust at source. Optical properties of aerosol layers developing in the atmosphere have been analyzed and lidar data are discussed in terms of profiles of aerosol backscatter coefficient at 355nm, 532nm, aerosol extinction coefficient at 355nm, aerosol depolarization ratio at 355nm and 532nm and water vapor mixing ratio. Depolarization ratio measured simultaneously at two wavelengths allowed also to study its dependence on the wavelength.

  11. 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; Krishnamurti, T. N.; Chen, Gao; Anderson, Bruce

    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.

  12. Clouds, Aerosols, and Precipitation in the Marine Boundary Layer: An Arm Mobile Facility Deployment

    SciTech Connect

    Wood, Robert; Wyant, Matthew; Bretherton, Christopher S.; Rémillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; de Szoeke, Simone; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, J. Christine; Mann, Julian A. L.; O’Connor, Ewan J.; Hogan, Robin J.; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palikonda, Rabindra; Albrecht, Bruce; Luke, Ed; Hannay, Cecile; Lin, Yanluan

    2015-03-01

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) 38 deployment at Graciosa Island in the Azores generated a 21 month (April 2009-December 2010) 39 comprehensive dataset documenting clouds, aerosols and precipitation using the Atmospheric 40 Radiation Measurement (ARM) Mobile Facility (AMF). The scientific aim of the deployment is 41 to gain improved understanding of the interactions of clouds, aerosols and precipitation in the 42 marine boundary layer. 43 Graciosa Island straddles the boundary between the subtropics and midlatitudes in the 44 Northeast Atlantic Ocean, and consequently experiences a great diversity of meteorological and 45 cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus 46 occurring regularly. Approximately half of all clouds contained precipitation detectable as radar 47 echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-48 11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide 49 range of aerosol conditions was sampled during the deployment consistent with the diversity of 50 sources as indicated by back trajectory analysis. Preliminary findings suggest important two-way 51 interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation 52 and cloud radiative properties while being controlled in part by precipitation scavenging. 53 The data from at Graciosa are being compared with short-range forecasts made a variety 54 of models. A pilot analysis with two climate and two weather forecast models shows that they 55 reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well, 56 but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to 57 be a long-term ARM site that became operational in October 2013.

  13. Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

    SciTech Connect

    Wood, Robert; Luke, Ed; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; deSzoeke, S.; Yuter, Sandra; Miller, Matthew; Mechem, David; Tselioudis, George; Chiu, Christine; Mann, Julia; O Connor, Ewan; Hogan, Robin; Dong, Xiquan; Miller, Mark; Ghate, Virendra; Jefferson, Anne; Min, Qilong; Minnis, Patrick; Palinkonda, Rabindra; Albrecht, Bruce; Hannay, Cecile; Lin, Yanluan

    2014-04-27

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulus and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.

  14. Clouds, aerosol, and precipitation in the Marine Boundary Layer: An ARM mobile facility deployment

    DOE PAGES

    Wood, Robert; Luke, Ed; Wyant, Matthew; Bretherton, Christopher S.; Remillard, Jasmine; Kollias, Pavlos; Fletcher, Jennifer; Stemmler, Jayson; deSzoeke, S.; Yuter, Sandra; et al

    2014-04-27

    The Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) deployment at Graciosa Island in the Azores generated a 21-month (April 2009-December 2010) comprehensive dataset documenting clouds, aerosols, and precipitation using the Atmospheric Radiation Measurement Program (ARM) Mobile Facility (AMF). The scientific aim of the deployment is to gain improved understanding of the interactions of clouds, aerosols, and precipitation in the marine boundary layer. Graciosa Island straddles the boundary between the subtropics and midlatitudes in the Northeast Atlantic Ocean and consequently experiences a great diversity of meteorological and cloudiness conditions. Low clouds are the dominant cloud type, with stratocumulusmore » and cumulus occurring regularly. Approximately half of all clouds contained precipitation detectable as radar echoes below the cloud base. Radar and satellite observations show that clouds with tops from 1-11 km contribute more or less equally to surface-measured precipitation at Graciosa. A wide range of aerosol conditions was sampled during the deployment consistent with the diversity of sources as indicated by back-trajectory analysis. Preliminary findings suggest important two-way interactions between aerosols and clouds at Graciosa, with aerosols affecting light precipitation and cloud radiative properties while being controlled in part by precipitation scavenging.The data from Graciosa are being compared with short-range forecasts made with a variety of models. A pilot analysis with two climate and two weather forecast models shows that they reproduce the observed time-varying vertical structure of lower-tropospheric cloud fairly well but the cloud-nucleating aerosol concentrations less well. The Graciosa site has been chosen to be a permanent fixed ARM site that became operational in October 2013.« less

  15. Mixed-layer ocean responses to anthropogenic aerosol dimming from 1870 to 2000

    NASA Astrophysics Data System (ADS)

    Dallafior, T. N.; Folini, D.; Knutti, R.; Wild, M.

    2016-01-01

    It is debated to what extent surface solar radiation (SSR) changes through varying anthropogenic aerosol emissions since industrialization affected surface temperatures (tsurf). We use mixed-layer ocean experiments with the general circulation model ECHAM6.1 and explicit aerosols (HAM2.2) to identify regions where this effect is discernible. For each decade from 1870 to 2000 we derive three equilibria: anthropogenic aerosol emissions and greenhouse gas concentrations at the respective decade's levels (ALL), either aerosols or greenhouse gases fixed at year 1850 levels (GHG and AERO). We duplicated parts of the experiments with different prescribed divergence of ocean heat transport (Q_ALL, Q_AERO, and Q_GHG). Comparing year 2000 with year 1870 equilibria, we find global average cooling of -1.4 K for AERO and warming of 1.4 K for GHG. ALL and Q_ALL warm by 0.6 K and 0.4 K, respectively. The way divergence of ocean heat transport is prescribed thus matters. Pattern correlations of year 2000 tsurf responses in ALL with the sum of AERO and GHG are higher (0.88) than with Q_ALL (0.71) confirming additivity of global patterns, but not of global means. The imprint of anthropogenic aerosols on tsurf response patterns in ALL is distinct, thus potentially detectable. Over the decades, ocean fractions affected by either changing aerosol optical depth or all-sky SSR vary in concert, supporting linkage between anthropogenic aerosols and all-sky SSR. SSR changes and tsurf responses are marginally collocated. Oceanic regions with strongest tsurf response to aerosol-induced SSR changes are the northern midlatitudes and North Pacific with tsurf sensitivities up to -0.7 K W m-2 SSR change.

  16. Mixed-layer ocean responses to anthropogenic aerosol dimming from 1870 to 2000

    NASA Astrophysics Data System (ADS)

    Dallafior, Tanja; Folini, Doris; Knutti, Reto; Wild, Martin

    2016-04-01

    It is still debated, to what extent anthropogenic aerosol-induced changes in surface solar radiation (SSR) since industrialization affected surface temperatures (tsurf). We use mixed-layer ocean (MLO) experiments with the general circulation model ECHAM6.1 and explicit aerosols (HAM2.2) to identify regions where this effect is discernible. For each decade from 1870 to 2000 we derive three equilibria: anthropogenic aerosol emissions and greenhouse gas concentrations at the respective decade's levels (ALL), either aerosols or greenhouse gases fixed at year 1850 levels (GHG and AERO). We duplicated parts of the experiments with different prescribed divergence of ocean heat transport (Q_ALL, Q_AERO, Q_GHG). Comparing year 2000 with year 1870 equilibria, we find global average cooling of -1.4K for AERO, and warming of 1.4K for GHG. ALL and Q_ALL warm by 0.6K and 0.4K, respectively. The way divergence of ocean heat transport is prescribed thus matters. Pattern correlations of year 2000 tsurf responses in ALL with the sum of AERO and GHG are higher (0.88) than with Q_ALL (0.71) confirming additivity of global patterns, but not of global means. The imprint of anthropogenic aerosols on tsurf response patterns in ALL is distinct, thus potentially detectable. Over the decades, ocean fractions affected by either changing aerosol optical depth or all-sky SSR vary in concert, supporting linkage between anthropogenic aerosols and all-sky SSR. SSR changes and tsurf responses are marginally collocated. Oceanic regions with strongest tsurf response to aerosol-induced SSR changes are the northern mid-latitudes and North Pacific with tsurf sensitivities up to -0.7K per Wm-2 SSR change. Results presented have been published under the same title in the Journal of Geophysical Research, Volume 121, DOI 10.1002/2015JD024070.

  17. Surface ozone-aerosol behaviour and atmospheric boundary layer structure in Saharan dusty scenario

    NASA Astrophysics Data System (ADS)

    Adame, Jose; Córdoba-Jabonero, Carmen; Sorrribas, Mar; Gil-Ojeda, Manuel; Toledo, Daniel; Yela, Margarita

    2016-04-01

    A research campaign was performed for the AMISOC (Atmospheric Minor Species relevant to the Ozone Chemistry) project at El Arenosillo observatory (southwest Spain) in May-June 2012. The campaign focused on the impact of Saharan dust intrusions at the Atmospheric Boundary Layer (ABL) and ozone-aerosol interactions. In-situ and remote-sensing techniques for gases and aerosols were used moreover to modelling analyses. Meteorology features, ABL structures and evolution, aerosol profiling distributions and aerosol-ozone interactions on the surface were analysed. Two four-day periods were selected according to non-dusty (clean conditions) and dusty (Saharan dust) situations. In both scenarios, sea-land breezes developed in the lower atmosphere, but differences were found in the upper levels. Results show that surface temperatures were greater than 3°C and humidity values were lower during dusty conditions than non-dusty conditions. Thermal structures on the surface layer (estimated using an instrument on a 100 m tower) show differences, mainly during nocturnal periods with less intense inversions under dusty conditions. The mixing layer during dusty days was 400-800 m thick, less than observed on non-dusty days. Dust also disturbed the typical daily ABL evolution. Stable conditions were observed during the early evening during intrusions. Aerosol extinction on dusty days was 2-3 times higher, and the dust was confined between 1500 and 5500 m. Back trajectory analyses confirmed that the dust had an African origin. On the surface, the particle concentration was approximately 3.5 times higher during dusty events, but the local ozone did not exhibit any change. The arrival of Saharan dust in the upper levels impacted the meteorological surface, inhibited the daily evolution of the ABL and caused an increase in aerosol loading on the surface and at higher altitudes; however, no dust influence was observed on surface ozone.

  18. Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Gysel, Martin; Rubach, Florian; Mentel, Thomas F.; Goger, Brigitta; Poulain, Laurent; Schlag, Patrick; Miettinen, Pasi; Pajunoja, Aki; Virtanen, Annele; Klein Baltink, Henk; Bas Henzing, J. S.; Größ, Johannes; Gobbi, Gian Paolo; Wiedensohler, Alfred; Kiendler-Scharr, Astrid; Decesari, Stefano; Facchini, Maria Cristina; Weingartner, Ernest; Baltensperger, Urs

    2016-06-01

    Vertical profiles of the aerosol particles hygroscopic properties, their mixing state as well as chemical composition were measured above northern Italy and the Netherlands. An aerosol mass spectrometer (AMS; for chemical composition) and a white-light humidified optical particle spectrometer (WHOPS; for hygroscopic growth) were deployed on a Zeppelin NT airship within the PEGASOS project. This allowed one to investigate the development of the different layers within the planetary boundary layer (PBL), providing a unique in situ data set for airborne aerosol particles properties in the first kilometre of the atmosphere. Profiles measured during the morning hours on 20 June 2012 in the Po Valley, Italy, showed an increased nitrate fraction at ˜ 100 m above ground level (a.g.l.) coupled with enhanced hygroscopic growth compared to ˜ 700 m a. g. l. This result was derived from both measurements of the aerosol composition and direct measurements of the hygroscopicity, yielding hygroscopicity parameters (κ) of 0.34 ± 0.12 and 0.19 ± 0.07 for 500 nm particles, at ˜ 100 and ˜ 700 m a. g. l., respectively. The difference is attributed to the structure of the PBL at this time of day which featured several independent sub-layers with different types of aerosols. Later in the day the vertical structures disappeared due to the mixing of the layers and similar aerosol particle properties were found at all probed altitudes (mean κ ≈ 0.18 ± 0.07). The aerosol properties observed at the lowest flight level (100 m a. g. l.) were consistent with parallel measurements at a ground site, both in the morning and afternoon. Overall, the aerosol particles were found to be externally mixed, with a prevailing hygroscopic fraction. The flights near Cabauw in the Netherlands in the fully mixed PBL did not feature altitude-dependent characteristics. Particles were also externally mixed and had an even larger hygroscopic fraction compared to the results in Italy. The mean κ from

  19. On impacts of overlying solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds

    NASA Astrophysics Data System (ADS)

    Fridlind, A. M.; Ackerman, A. S.; Zhou, X.; Wood, R.; Kollias, P.

    2015-12-01

    Early cloud-scale modeling work on effects of solar-absorbing aerosol layers focused on the desiccation of shallow cumulus clouds embedded with such layers, resulting from the reduction in relative humidity induced by solar heating, as well as reduced vertical mixing from stabilization of the boundary layer. Such a cloud response serves as a positive radiative forcing at the top of atmosphere, tending to warm the climate system. Subsequent work has largely targeted the impact of overlying solar-absorbing aerosol layers on stratiform clouds in the marine boundary layer, in which the solar heating increases the strength of the temperature inversion capping the boundary layer, which reduces entrainment of overlying air into the boundary layer. Because entrainment typically (but not always) reduces the average relative humidity of the boundary layer and thereby leads to a thinner cloud layer, a reduction in entrainment induced by an absorbing aerosol layer leads to a thicker cloud layer and a negative radiative forcing at the top of atmosphere, tending to cool the climate system. Here we use large-eddy simulations to assess the effects of overlying solar-absorbing aerosol layers on the transition of stratocumulus to trade cumulus clouds. Beyond the impact on the inversion strength, we also consider the changes induced by microphysical response to entrained aerosol that serve as cloud condensation nuclei, as well as reduction in solar heating of the cloud induced by the overlying aerosol layer. Observationally-based transition cases used in a recent large-eddy simulation intercomparison will be used as a starting point for the model setup, along with idealized aerosol layer properties based on remote sensing and in situ observations. We will also use the same simulation setups to evaluate and compare the response of the single column model version of the GISS climate model (with two-moment microphysics).

  20. Determination of smoke plume and layer heights using scanning lidar data.

    PubMed

    Kovalev, Vladimir A; Petkov, Alexander; Wold, Cyle; Urbanski, Shawn; Min Hao, Wei

    2009-10-01

    The methodology of using mobile scanning lidar data for investigation of smoke plume rise and high-resolution smoke dispersion is considered. The methodology is based on the lidar-signal transformation proposed recently [Appl. Opt. 48, 2559 (2009)]. In this study, similar methodology is used to create the atmospheric heterogeneity height indicator (HHI), which shows all heights at which the smoke plume heterogeneity was detected by a scanning lidar. The methodology is simple and robust. Subtraction of the initial lidar signal offset from the measured lidar signal is not required. HHI examples derived from lidar scans obtained with the U.S. Forest Service, Fire Sciences Laboratory mobile lidar in areas polluted by wildfires are presented, and the basic details of the methodology are discussed. PMID:19798367

  1. 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

  2. Radiosonde aerosol counter for vertical profiling of atmospheric dust layers

    NASA Astrophysics Data System (ADS)

    Ulanowski, Z.; Hirst, E.; Kaye, P. H.; Harrison, R. G.; Nicoll, K. A.; Rogers, G.

    2010-05-01

    A low-cost, miniature aerosol particle counter has been developed, intended for use with balloon-borne meteorological radiosondes. It is particularly suitable for airborne mineral dust measurements. Ambient air is drawn into the counter using a diaphragm pump at a rate of 0.5 litre per minute. The counter detects particles in the airstream using a diode laser and a photodiode. Output from the photodiode is digitised into 5 size bins, with minimum particle diameters equivalent to 0.6, 1.4, 2.6, 5.4 and 10.6 micrometers. The counter is interfaced to a Vaisala RS92 radiosonde, which transmits data from the counter together with meteorological parameters and GPS-derived position to a ground based receiver at 1 Hz rate. Statistically significant particle size distributions can be obtained once a second for number concentrations down to about 100,000 particle per litre (within the measured size range), or correspondingly less at lower temporal resolutions. At the same time, the counter is capable of measuring dust number concentrations exceeding a million per litre without incurring significant errors. Soundings during the DREAME campaign in Kuwait (Ulanowski et al. EGU 2010, AS4.7) and on Cape Verde Islands (Nicoll et al. EGU 2010, AS4.7) provided dust concentration profiles with a typical vertical resolution of 4 m. Comparisons with integrated dust column size distribution measurements from AERONET sun photometers showed good agreement in two out of three cases where near-simultaneous retrievals were available. Optical thickness calculations based on the size distributions measured in Kuwait, with the assumption that the dust particles were prolate spheroids, agreed with the AERONET optical thickness at 675 nm to within 15%.

  3. Investigation on F layer height rise and equatorial spread F onset time: Signature of standing large-scale wave

    NASA Astrophysics Data System (ADS)

    Joshi, Lalit Mohan; Balwada, S.; Pant, T. K.; Sumod, S. G.

    2015-04-01

    Equatorial spread F observations have been categorized into three categories based on ionograms recorded over Sriharikota. First category comprised cases where the onset of equatorial spread F (ESF) was concurrent with the peak h'F time. Second and third categories comprised cases where the onset of ESF happened with a delay of 30 min and more than 30 min, respectively, with reference to the peak h'F time. Average peak h'F in the first category was more than 35 km higher than that in the second and third categories. Also, the peak vertical (upward) plasma drift was higher in the first category. Assuming the genesis of F region irregularity to have happened at or before the time of F layer attaining the peak height, late onset of ESF indicates the genesis of irregularities to have happened westward of Sriharikota. The fact that the peak h'F values were remarkably different in the three categories indicates a zonal variation of eastward electric field and postsunset height rise of F layer. The relative magnitude of the F layer height rise in the three different categories over Sriharikota has also been found to be significantly different than that over Thumba, an equatorial (magnetic) station located ~360 km westward of Sriharikota longitude. This scenario points toward the existence of a large-scale zonal standing wave in the F layer and its important role in F region instability process. Results presented in the manuscript have been discussed in the light of current understanding on the large-scale wave structure.

  4. Wintertime aerosol characteristics over the Indo-Gangetic Plain (IGP): Impacts of local boundary layer processes and long-range transport

    NASA Astrophysics Data System (ADS)

    Nair, Vijayakumar S.; Moorthy, K. Krishna; Alappattu, Denny P.; Kunhikrishnan, P. K.; George, Susan; Nair, Prabha R.; Babu, S. Suresh; Abish, B.; Satheesh, S. K.; Tripathi, Sachchida Nand; Niranjan, K.; Madhavan, B. L.; Srikant, V.; Dutt, C. B. S.; Badarinath, K. V. S.; Reddy, R. Ramakrishna

    2007-07-01

    The Indo-Gangetic Plain (IGP) encompasses a vast area, (accounting for ˜21% of the land area of India), which is densely populated (accommodating ˜40% of the Indian population). Highly growing economy and population over this region results in a wide range of anthropogenic activities. A large number of thermal power plants (most of them coal fed) are clustered along this region. Despite its importance, detailed investigation of aerosols over this region is sparse. During an intense field campaign of winter 2004, extensive aerosol and atmospheric boundary layer measurements were made from three locations: Kharagpur (KGP), Allahabad (ALB), and Kanpur (KNP), within the IGP. These data are used (1) to understand the regional features of aerosols and BC over the IGP and their interdependencies, (2) to compare it with features at locations lying at far away from the IGP where the conditions are totally different, (3) to delineate the effects of mesoscale processes associated with changes in the local atmospheric boundary layer (ABL), (4) to investigate the effects of long-range transport or moving weather phenomena in modulating the aerosol properties as well as the ABL characteristics, and (5) to examine the changes as the season changes over to spring and summer. Our investigations have revealed very high concentrations of aerosols along the IGP, the average mass concentrations (MT) of total aerosols being in the range 260 to 300 μg m-3 and BC mass concentrations (MB) in the range 20 to 30 μg m-3 (both ˜5 to 8 times higher than the values observed at off-IGP stations) during December 2004. Despite, BC constituted about 10% to the total aerosol mass concentration, a value quite comparable to those observed elsewhere over India for this season. The dynamics of the local atmospheric boundary layer (ABL) as well as changes in local emissions strongly influence the diurnal variations of MT and MB, both being inversely correlated with the mixed layer height (Zi) and the

  5. Nature, Origin, Potential Composition, and Climate Impact of the Asian Tropopause Aerosol Layer (ATAL)

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Thomason, L. W.; Natarajan, M.; Bedka, K.; Wienhold, F.; Bian J.; Martinsson, B.

    2015-01-01

    Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has more than doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. Here we show remote and in-situ observations, together with results from a chemical transport model (CTM), to explore the likely composition, origin, and radiative forcing of the ATAL. We show in-situ balloon measurements of aerosol backscatter, which support the high levels observed by CALIPSO since 2006. We also show in situ measurements from aircraft, which indicate a predominant carbonaceous contribution to the ATAL (Carbon/Sulfur ratios of 2- 10), which is supported by the CTM results. We show that the peak in ATAL aerosol lags by 1 month the peak in CO from MLS, associated with deep convection over Asia during the summer monsoon. This suggests that secondary formation and growth of aerosols in the upper troposphere on monthly timescales make a significant contribution to ATAL. Back trajectory calculations initialized from CALIPSO observations provide evidence that deep convection over India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere.

  6. Comparison of Atmospheric Column Optical Depth Measurements for Urban Reno, NV with Three Different Sun Photometers and In Situ Measurements Combined with Boundary Layer Height Estimation

    NASA Astrophysics Data System (ADS)

    Loria Salazar, S. M.; Arnott, W. P.; Moosmuller, H.; Sumlin, B.; Karr, D.

    2011-12-01

    Reno, Nevada, USA is located in a mountain valley often characterized by very dry conditions, clear sky and red sunsets during the summer season, with rare incursions of monsoonal moisture. This city is subject to moderately strong nocturnal inversions nearly every day in summer. Urban aerosols, wind blown dust, as well as occasional biomass burning smoke from natural and non-natural fires all contribute to the optical depth. Because of its geographical position, drastic changes in weather conditions and variations in aerosol optical properties make Reno an excellent location for evaluating measurements of aerosol optical depth in order to determine particulate air pollution concentration as well as to provide input for models of atmospheric radiation transfer and evaluation of satellite-based aerosol optical sensing measurements. Aerosol optical depth can be calculated by in situ photoacoustic measurements of aerosol light absorption and reciprocal nephelometer scattering coefficients and estimation of aerosol mixing height. LED-based hand-held sun photometers are commonly used as inexpensive instruments for informal networks. However, the LED emission wavelength maximum and bandwidth are higher and narrower than the LED reception wavelength spectrum, necessitating empirical determination of an equivalent wavelength. The manually operated spectrometer and Cimel sun photometer measurements provide the most accurate and precise column aerosol optical depth. This paper makes a comparison between these four instruments for measurements obtained during the summer and fall seasons in order to study how the total and aerosol optical depth change during dry and moist conditions. Ångström exponents of extinction and absorption are also analyzed to provide insight on aerosol size distribution and composition, respectively.

  7. Estimating Mixing Heights Using Microwave Temperature Profiler

    NASA Technical Reports Server (NTRS)

    Nielson-Gammon, John; Powell, Christina; Mahoney, Michael; Angevine, Wayne

    2008-01-01

    A paper describes the Microwave Temperature Profiler (MTP) for making measurements of the planetary boundary layer thermal structure data necessary for air quality forecasting as the Mixing Layer (ML) height determines the volume in which daytime pollution is primarily concentrated. This is the first time that an airborne temperature profiler has been used to measure the mixing layer height. Normally, this is done using a radar wind profiler, which is both noisy and large. The MTP was deployed during the Texas 2000 Air Quality Study (TexAQS-2000). An objective technique was developed and tested for estimating the ML height from the MTP vertical temperature profiles. In order to calibrate the technique and evaluate the usefulness of this approach, estimates from a variety of measurements during the TexAQS-2000 were compared. Estimates of ML height were used from radiosondes, radar wind profilers, an aerosol backscatter lidar, and in-situ aircraft measurements in addition to those from the MTP.

  8. Secondary aerosol formation in the planetary boundary layer: observations on board on a Zeppelin and analysis by back plume approach

    NASA Astrophysics Data System (ADS)

    Kazanas, Konstantinos; Rubach, Florian; Tillmann, Ralf; Mentel, Thomas; Elbern, Hendrik; Wahner, Andreas; Zeppelin Pegasos-Team 2012

    2014-05-01

    The airship Zeppelin NT is an airborne platform capable of flying at low speed throughout the entire planetary boundary layer (PBL), thus the Zeppelin is an ideal platform to study regional processes in the lowest layers of the atmosphere with high spatial resolution. Atmospheric aerosol as a medium long lived tracer substance is of particular interest due to its influence on the global radiation budget. Due to its lifetime of up to several days secondary aerosol at a certain location can result from local production or from transport processes. Flight patterns during the PEGASOS campaign 2012 in the Po Valley included vertical profiles and transects through regions of interest We analysed one flight with North-South transects between the Apennin and San Pietro Capofiume and one flight with vertical profiles near the supersite San Pietro Capofiume to shed light on local production and transport processes. Model analyses were performed by using 12 hour back plumes for selected points of measurements to determine the regions which contributed to the air mass under observation. This analysis was done using the EURopean Air pollution Dispersion and Inverse Modelling (EURAD-IM) system. As a novel method, adjoint (backward) plumes are applied to identify the spread of originating air masses in terms of horizontal and vertical extension, and the influence of precursor species. Flight patterns include 5 points of measurement along the transect on 21.06.2012 and the lowest (ca. 80m), highest (ca. 708m), and medium height (299 to 464m) of 7 vertical profiles on the 20.06.2012.

  9. Investigation of wintertime cold-air pools and aerosol layers in the Salt Lake Valley using a lidar ceilometer

    NASA Astrophysics Data System (ADS)

    Young, Joseph Swyler

    This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this

  10. To examine the association between oscillations of the stratospheric aerosol layer peaks and different types of clouds

    NASA Astrophysics Data System (ADS)

    Mane, P. B.

    2014-11-01

    Aerosol measurements have been carried out at Kolhapur (16°42'N, 74°14'E) by using newly designed Semiautomatic Twilight Photometer. The system is a ground based simple and inexpensive but very sensitive passive remote sensing technique. The altitudes of the Junge layer peaks on measurement days were derived from the aerosol vertical profiles. One attempt is made to examine the association between oscillations of the stratospheric aerosol layer peaks and different types of clouds. The values of AND for the Junge layer peaks for each observational day were also calculated. The graph between AND at peak point of Junge layer and day numbers was also studied in comparison with High, Medium and Low level clouds. There is an annual variation in the altitude of the peak of Junge layer also. Its maximum is observed during January. The annual variation of the altitude of the peak of Junge layer and the AND of Junge layer peak showed opposite phase relation.

  11. CO2-flux measurements above the Baltic Sea at two heights: flux gradients in the surface layer?

    NASA Astrophysics Data System (ADS)

    Lammert, A.; Ament, F.

    2015-11-01

    The estimation of CO2 exchange between the ocean and the atmosphere is essential to understand the global carbon cycle. The eddy-covariance technique offers a very direct approach to observe these fluxes. The turbulent CO2 flux is measured, as well as the sensible and latent heat flux and the momentum flux, a few meters above the ocean in the atmosphere. Assuming a constant-flux layer in the near-surface part of the atmospheric boundary layer, this flux equals the exchange flux between ocean and atmosphere. The purpose of this paper is the comparison of long-term flux measurements at two different heights above the Baltic Sea to investigate this assumption. The results are based on a 1.5-year record of quality-controlled eddy-covariance measurements. Concerning the flux of momentum and of sensible and latent heat, the constant-flux layer theory can be confirmed because flux differences between the two heights are insignificantly small more than 95 % of the time. In contrast, significant differences, which are larger than the measurement error, occur in the CO2 flux about 35 % of the time. Data used for this paper are published at http://doi.pangaea.de/10.1594/PANGAEA.808714.

  12. Measurement of the height of the solar CO layer during the 11 July 1991 eclipse

    SciTech Connect

    Clark, T.A.; Naylor, D.A.; Tompkins, G.J.; Lindsey, C.A.; Jefferies, J.T.; Becklin, E.E. ); Roellig, T.L.; Harrison, R.A.; Carter, M.; Braun, D.C.; Watt, G.

    1992-01-01

    Normal' chromospheric indicators such as CaII H K, MgII h k, HI Ly[alpha] and the UV and far IR continua all show the presence in the solar atmosphere of a distinct temperature inversion with a minimum temperature of about 4300 K at 550 km above the photosphere and a temperature rise in the lower chromosphere. In distinct contrast, the characteristics of lines in the V-R bands of CO show the presence of cool plasma extending over this height range, with T < 3800 K. Present models suggest that the CO exists only in clouds of limited vertical extent above supergranular cells, surrounded by a hotter chromospheric network containing embedded magnetic flux tubes. One remaining uncertainty is the height and vertical extent of these CO clouds. Near IR total eclipse observations from Mauna Kea on 11 July 1991 have provided a measure of the limb extension of CO emission in the fundamental V-R band between 4.4 5.4 [mu]m compared to both the IR continuum and visible limbs. The CO limb' is found to be 125 +/- -15 km above this visible limb, or 465 km above [tau][sub 0.5] = 1, which places the main CO concentration just below the temperature minimum but above the [tau][sub CO] = 1 level of 430 km in the semi-empirical hot chromosphere' model of Avrett but below the equivalent level of 560 km in the cool' radiative equilibrium model of Anderson.

  13. Assessment of planetary boundary layer and residual layer heights in the Northeastern U.S. using Lidar, a network of surface observations, and the WRF-STILT model

    NASA Astrophysics Data System (ADS)

    Barrera, Y.; Nehrkorn, T.; Hegarty, J. D.; Wofsy, S. C.; Gottlieb, E.; Sargent, M. R.; Decola, P.; Jones, T.

    2015-12-01

    Simulation of the planetary boundary layer (PBL) and residual layer (RL) are key requirements for forecasting air quality in cities and detecting transboundary air pollution events. This study combines information from a network of Mini Micropulse Lidar (MPL) instruments, the CALIOP satellite, meteorological and air pollution measuring sensors, and a particle-transport model to critically test mesoscale transport models at the regional level. Aerosol backscattering measurements were continuously taken with MPL units in various locations within the Northeastern U.S., between September 2012 to August 2015. Data is analyzed using wavelet covariance transforms and image processing techniques. Initial results for the city of Boston show a PBL growth rate between approx. 150 and 300 meters per hour, in the morning to early afternoon (~12-19 UTC). The RL was present throughout the night and day at approx. 1.3 to 2.0 km. Transboundary air pollution events were detected and quantified, and variations in concentrations of greenhouse gases and aerosols were also evaluated. Results were compared to information retrieved from Weather and Research Forecasting (WRF) model and the Stochastic Time-Inverted Lagrangian Transport (STILT) model.

  14. Sensitivity of Turbine-Height Wind Speeds to Parameters in Planetary Boundary-Layer and Surface-Layer Schemes in the Weather Research and Forecasting Model

    NASA Astrophysics Data System (ADS)

    Yang, Ben; Qian, Yun; Berg, Larry K.; Ma, Po-Lun; Wharton, Sonia; Bulaevskaya, Vera; Yan, Huiping; Hou, Zhangshuan; Shaw, William J.

    2016-07-01

    We evaluate the sensitivity of simulated turbine-height wind speeds to 26 parameters within the Mellor-Yamada-Nakanishi-Niino (MYNN) planetary boundary-layer scheme and MM5 surface-layer scheme of the Weather Research and Forecasting model over an area of complex terrain. An efficient sampling algorithm and generalized linear model are used to explore the multiple-dimensional parameter space and quantify the parametric sensitivity of simulated turbine-height wind speeds. The results indicate that most of the variability in the ensemble simulations is due to parameters related to the dissipation of turbulent kinetic energy (TKE), Prandtl number, turbulent length scales, surface roughness, and the von Kármán constant. The parameter associated with the TKE dissipation rate is found to be most important, and a larger dissipation rate produces larger hub-height wind speeds. A larger Prandtl number results in smaller nighttime wind speeds. Increasing surface roughness reduces the frequencies of both extremely weak and strong airflows, implying a reduction in the variability of wind speed. All of the above parameters significantly affect the vertical profiles of wind speed and the magnitude of wind shear. The relative contributions of individual parameters are found to be dependent on both the terrain slope and atmospheric stability.

  15. A Numerical Study of Sea-Spray Aerosol Motion in a Coastal Thermal Internal Boundary Layer

    NASA Astrophysics Data System (ADS)

    Liang, Tinghao; Yu, Xiping

    2016-08-01

    A three-dimensional large-eddy simulation model is applied to the study of sea-spray aerosol transport, dispersion and settling in the coastal thermal internal boundary layer (IBL) formed by cool airflow from the open sea to the warm land. An idealized situation with constant inflow from the ocean and constant heat flux over the coastal land is considered. The numerical results confirm that the thickness of the coastal thermal IBL increases with the distance from the coastline until the outer edge of the IBL penetrates into the capping inversion layer. The thickness increases also with time until a fully-developed thermal boundary layer is formed. In addition, the thickness of the coastal thermal IBL increases more rapidly when the heat flux over the land is greater. Existence of large-scale eddies within the thermal IBL is identified and the turbulence intensity within the thermal IBL is also found to be significantly higher than that above. It is also indicated that the vertical position of the maximum concentration does not occur at the surface but increases as sea-spray aerosols are transported inland. The vertical position of the maximum flux of sea-spray aerosols within the coastal thermal IBL is shown to coincide with that of the maximum vertical velocity fluctuations when the coastal thermal IBL is fully developed with increased distance in the airflow direction.

  16. The Impact of Monthly Variation of the Pacific-North America (PNA) Teleconnection Pattern on Wintertime Surface-layer Aerosol Concentrations in the United States

    NASA Astrophysics Data System (ADS)

    Feng, J.; Liao, H.; Li, J.

    2015-12-01

    The Pacific-North America teleconnection (PNA) is the leading general circulation pattern in the troposphere over the region of North Pacific to North America during wintertime. The PNA exhibits positive (negative) phases with positive (negative) anomalies in geopotential height in the vicinity of Hawaii and over the intermountain region of North America, and negative (positive) anomalies in geopotential height over south of the Aleutian Islands and the Gulf Coast region of the United States. This study examined the impacts of monthly variation of the PNA phase on wintertime surface-layer aerosol concentrations in the United States by analyzing observations during 1999-2013 from the Air Quality System of Environmental Protection Agency (EPA-AQS) and the model results for 1986-2006 from the global three-dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem). The composite analyses on the EPA-AQS observations over 1999-2003 showed that the average PM2.5 concentrations were higher in the PNA positive phases than in the PNA negative phases by 1.0 μg m-3 (8.6%), 2.1μg m-3 (24.1%), and 1.1 μg m-3 (10.6%) in the eastern, western, and whole of United States, respectively. Relative to the PNA negative phases, the number of exceedance days (days with the PM2.5 concentrations exceeding 35 μg m-3) in the PNA positive phases increased by 5-8 days month-1 in California and the contiguous Great Salt Lake and by 2-3 days month-1 in Iowa. The simulated geographical patterns of the differences in concentrations of PM2.5, nitrate, sulfate, ammonium, OC, and BC between the PNA positive and negative phases were similar to observations. The PNA influences surface-layer aerosol concentrations in the United States by changing meteorological variables such as temperature, precipitation, planetary boundary layer height, relative humidity, and wind speed. We found that that the PNA-induced variation in planetary boundary layer height was the most dominant

  17. Impacts of elevated-aerosol-layer and aerosol type on the correlation of AOD and particulate matter with ground-based and satellite measurements in Nanjing, southeast China.

    PubMed

    Han, Yong; Wu, Yonghua; Wang, Tijian; Zhuang, Bingliang; Li, Shu; Zhao, Kun

    2015-11-01

    Assessment of the correlation between aerosol optical depth (AOD) and particulate matter (PM) is critical to satellite remote sensing of air quality, e.g. ground PM10 and ground PM2.5. This study evaluates the impacts of aloft-aerosol-plume and aerosol-type on the correlation of AOD-PM by using synergistic measurement of a polarization-sensitive Raman-Mie lidar, CIMEL sunphotometer (SP) and TEOM PM samplers, as well as the satellite MODIS and CALIPSO, during April to July 2011 in Nanjing city (32.05(○)N/118.77(○)E), southeast China. Aloft-aerosol-layer and aerosol types (e.g. dust and non-dust or urban aerosol) are identified with the range-resolved polarization lidar and SP measurements. The results indicate that the correlations for AOD-PM10 and AOD-PM2.5 can be much improved when screening out the aloft-aerosol-layer. The linear regression slopes show significant differences for the dust and non-dust dominant aerosols in the planetary boundary layer (PBL). In addition, we evaluate the recent released MODIS-AOD product (Collection 6) from the "dark-target" (DT) and "deep-blue" (DB) algorithms and their correlation with the PM in Nanjing urban area. The results verify that the MODIS-DT AODs show a good correlation (R = 0.89) with the SP-AOD but with a systematic overestimate. In contrast, the MODIS-DB AOD shows a moderate correlation (R = 0.66) with the SP-AOD but with a smaller regression intercept (0.07). Furthermore, the moderately high correlations between the MODIS-AOD and PM10 (PM2.5) are indicated, which suggests the feasibility of PM estimate using the MODIS-AOD in Nanjing city. PMID:26071961

  18. 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.; Hipskind, R. Stephen (Technical Monitor)

    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)).

  19. 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).

  20. CO2-flux measurements above the Baltic Sea at two heights: flux gradients in the surface layer

    NASA Astrophysics Data System (ADS)

    Lammert, A.; Ament, F.

    2015-07-01

    The estimation of CO2 exchange between the ocean and the atmosphere is essential to understand the global carbon cycle. The eddy-covariance technique offers a very direct approach to observe these fluxes. The turbulent CO2 flux is measured as well as the sensible and latent heat flux and the momentum flux, a few meters above the ocean in the atmosphere. Assuming a constant-flux layer in the near surface part of the atmospheric boundary, this flux equals the exchange flux between ocean and atmosphere. The goal of this paper is the comparison of long-term flux measurements at two different heights above the Baltic Sea due to this assumption. The results are based on an one-and-a-half year record of quality controlled eddy covariance measurements. Concerning the flux of momentum and of sensible and latent heat, the constant-flux layer theory can be validated because flux gradients between the two heights are more than 95 % of the time insignificantly small. In contrast, significant gradients, which are larger than the measurement error, occur for the CO2 flux in nearly 35 % of the time. Data, used for this paper are published at http://doi.pangaea.de/10.1594/PANGAEA.808714.

  1. Interpretation of FRESCO cloud retrievals in case of absorbing aerosol events

    NASA Astrophysics Data System (ADS)

    Wang, P.; Tuinder, O. N. E.; Tilstra, L. G.; de Graaf, M.; Stammes, P.

    2012-10-01

    Cloud and aerosol information is needed in trace gas retrievals from satellite measurements. The Fast REtrieval Scheme for Clouds from the Oxygen A band (FRESCO) cloud algorithm employs reflectance spectra of the O2 A band around 760 nm to derive cloud pressure and effective cloud fraction. In general, clouds contribute more to the O2 A band reflectance than aerosols. Therefore, the FRESCO algorithm does not correct for aerosol effects in the retrievals and attributes the retrieved cloud information entirely to the presence of clouds, and not to aerosols. For events with high aerosol loading, aerosols may have a dominant effect, especially for almost cloud free scenes. We have analysed FRESCO cloud data and Absorbing Aerosol Index (AAI) data from the Global Ozone Monitoring Experiment (GOME-2) instrument on the Metop-A satellite for events with typical absorbing aerosol types, such as volcanic ash, desert dust and smoke. We find that the FRESCO effective cloud fractions are correlated with the AAI data for these absorbing aerosol events and that the FRESCO cloud pressure contains information on aerosol layer pressure. For cloud free scenes, the derived FRESCO cloud pressure is close to the aerosol layer pressure, especially for optically thick aerosol layers. For cloudy scenes, if the strongly absorbing aerosols are located above the clouds, then the retrieved FRESCO cloud pressure may represent the height of the aerosol layer rather than the height of the clouds. Combining FRESCO and AAI data, an estimate for the aerosol layer pressure can be given.

  2. Single-Particle Black Carbon Aerosol Verticle Profiles From the Boundary Layer to the Lower Stratosphere

    NASA Astrophysics Data System (ADS)

    Schwarz, J. P.; Gao, R. S.; Fahey, D. W.; Laurel, W. A.; Thomson, D. S.; Kok, G. L.; Baumgardner, D.; Wilson, J. C.; Lopez, J.; Aikin, K.; Jost, H.; Thompson, T. L.; Reeves, J. M.; Lowenstein, M.

    2005-12-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, TX. The SP2 uses laser-induced incandescence to directly measure the mass of individual black-carbon (BC) particles in the mass range of ~0.3-300 fg. Scattered light is used to size non-absorbing aerosols in the range of ~150 - 700 nm diameter. Data from two mid-latitude flights has been used to generate size distributions and profiles of both aerosol types from the boundary layer to the lower stratosphere. Results for scattering aerosol concentrations are in good agreement with typical particle spectrometer measurements in the same region. Mass mixing ratios of BC between 5 and 18.7 km were roughly an order of magnitude lower than typical values as reported with wire impactor measurements and as predicted by two global BC models. The impact of this discrepancy on estimates of direct radiative forcing of BC aerosol will also be discussed.

  3. Characteristics of aerosol at a lower atmospheric layer in DRAGON field campaign

    NASA Astrophysics Data System (ADS)

    KUJI, M.; Azuma, Y.; Kitakoga, S.; Sano, I.; Holben, B. N.

    2013-12-01

    Air pollution arises severely over East Asia with the rapid economic development nowadays. Monitoring the atmospheric environment, as one of the purposes, an intensive field campaign, Distributed Regional Aerosol Gridded Observation Networks (DRAGON), was carried out in the spring of year 2012, led by National Aeronautics and Space Administration (NASA). At that time, atmospheric phenomena such as Yellow sand and haze events were observed at Nara in the western part of Japan, as one of the DRAGON observation sites. The atmospheric events were characterized with the AErosol RObotic NETwork (AERONET) data. As a result of the data analysis, it was found that more light-absorbing and smaller particles dominated at the lower than upper atmospheric layer for the Kosa event in particular. A backward trajectory analysis suggested that the Yellow sand event traveled over the East Asian industrial cities, which could lead to a mixture of sand and air pollutants with moderate particle size and light-absorptivity. In addition, visibility observation was evaluated quantitatively with AERONET data in the DRAGON campaign since eye observation was inherently semi-quantitative. The extinction coefficient estimated from visibility was compared to that from AERONET. As a result, it was found that the extinction coefficients were generally consistent to each other. But there were some discrepancies, which could be caused with the atmospheric phenomena or aerosol types. It is confirmed that visibility is strongly influenced with aerosols in the case of severe atmospheric phenomena in particular.

  4. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer (CAP-MBL) Final Campaign Report

    SciTech Connect

    Wood, R.

    2016-01-01

    The extensive coverage of low clouds over the subtropical eastern oceans greatly impacts the current climate. In addition, the response of low clouds to changes in atmospheric greenhouse gases and aerosols is a major source of uncertainty, which thwarts accurate prediction of future climate change. Low clouds are poorly simulated in climate models, partly due to inadequate long-term simultaneous observations of their macrophysical and microphysical structure, radiative effects, and associated aerosol distribution in regions where their impact is greatest. The thickness and extent of subtropical low clouds is dependent on tight couplings between surface fluxes of heat and moisture, radiative cooling, boundary layer turbulence, and precipitation (much of which evaporates before reaching the ocean surface and is closely connected to the abundance of cloud condensation nuclei). These couplings have been documented as a result of past field programs and model studies. However, extensive research is still required to achieve a quantitative understanding sufficient for developing parameterizations, which adequately predict aerosol indirect effects and low cloud response to climate perturbations. This is especially true of the interactions between clouds, aerosol, and precipitation. These processes take place in an ever-changing synoptic environment that can confound interpretation of short time period observations.

  5. Assessment of aerosol optical property and radiative effect for the layer decoupling cases over the northern South China Sea during the 7-SEAS/Dongsha Experiment

    NASA Astrophysics Data System (ADS)

    Pani, Shantanu Kumar; Wang, Sheng-Hsiang; Lin, Neng-Huei; Tsay, Si-Chee; Lolli, Simone; Chuang, Ming-Tung; Lee, Chung-Te; Chantara, Somporn; Yu, Jin-Yi

    2016-05-01

    The aerosol radiative effect can be modulated by the vertical distribution and optical properties of aerosols, particularly when aerosol layers are decoupled. Direct aerosol radiative effects over the northern South China Sea (SCS) were assessed by incorporating an observed data set of aerosol optical properties obtained from the Seven South East Asian Studies (7-SEAS)/Dongsha Experiment into a radiative transfer model. Aerosol optical properties for a two-layer structure of aerosol transport were estimated. In the radiative transfer calculations, aerosol variability (i.e., diversity of source region, aerosol type, and vertical distribution) for the complex aerosol environment was also carefully quantified. The column-integrated aerosol optical depth (AOD) at 500 nm was 0.1-0.3 for near-surface aerosols and increased 1-5 times in presence of upper layer biomass-burning aerosols. A case study showed the strong aerosol absorption (single-scattering albedo (ω) ≈ 0.92 at 440 nm wavelength) exhibited by the upper layer when associated with predominantly biomass-burning aerosols, and the ω (≈0.95) of near-surface aerosols was greater than that of the upper layer aerosols because of the presence of mixed type aerosols. The presence of upper level aerosol transport could enhance the radiative efficiency at the surface (i.e., cooling) and lower atmosphere (i.e., heating) by up to -13.7 and +9.6 W m-2 per AOD, respectively. Such enhancement could potentially modify atmospheric stability, can influence atmospheric circulation, as well as the hydrological cycle over the tropical and low-latitude marginal northern SCS.

  6. Interaction between aerosol and the planetary boundary layer depth at sites in the US and China

    NASA Astrophysics Data System (ADS)

    Sawyer, V. R.

    2015-12-01

    The depth of the planetary boundary layer (PBL) defines a changing volume into which pollutants from the surface can disperse, which affects weather, surface air quality and radiative forcing in the lower troposphere. Model simulations have also shown that aerosol within the PBL heats the layer at the expense of the surface, changing the stability profile and therefore also the development of the PBL itself: aerosol radiative forcing within the PBL suppresses surface convection and causes shallower PBLs. However, the effect has been difficult to detect in observations. The most intensive radiosonde measurements have a temporal resolution too coarse to detect the full diurnal variability of the PBL, but remote sensing such as lidar can fill in the gaps. Using a method that combines two common PBL detection algorithms (wavelet covariance and iterative curve-fitting) PBL depth retrievals from micropulse lidar (MPL) at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared to MPL-derived PBL depths from a multiyear lidar deployment at the Hefei Radiation Observatory (HeRO). With aerosol optical depth (AOD) measurements from both sites, it can be shown that a weak inverse relationship exists between AOD and daytime PBL depth. This relationship is stronger at the more polluted HeRO site than at SGP. Figure: Mean daily AOD vs. mean daily PBL depth, with the Nadaraya-Watson estimator overlaid on the kernel density estimate. Left, SGP; right, HeRO.

  7. 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; Browell, Edward; Kooi, Susan; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Dunion, Jason; Heymsfield, Gerry; Anderson, Bruce

    2008-01-01

    LASE (Lidar Atmospheric Sensing Experiment) onboard the NASA DC-8 was used to measure high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern Atlantic region during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment, which was conducted from August 15 to September 12, 2006. These measurements were made in conjunction with flights designed to study African Easterly Waves (AEW), Tropical Disturbances (TD), and Saharan Aerosol Layers (SALs) as well as flights performed in clear air and convective regions. As a consequence of their unique radiative properties and dynamics, SAL layers have a significant influence in the development of organized convection associated with TD. Interactions of the SAL with tropical air during early stages of the development of TD were observed. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on TDs and hurricanes. Seven AEWs were studied and four of these evolved into tropical storms and three did not. Three out of the four tropical storms evolved into hurricanes.

  8. Measurements and determination of the marine coarse aerosol fluxes in near marine boundary layer.

    NASA Astrophysics Data System (ADS)

    Markuszewski, Piotr; Petelski, Tomasz; Zielinski, Tymon; Strzalkowska, Agata; Pakszys, Paulina; Makuch, Przemyslaw; Kowalczyk, Jakub

    2014-05-01

    Studies of production and transport of aerosol over the sea are very important for many areas of knowledge. Marine aerosols emitted from the sea surface help to clean the boundary layer from other aerosol particles. The emitted droplets do not dry out in the highly humid surface layer air and because of their sizes most of them are deposited quickly at the sea surface. Therefore, marine aerosols have many features of rain i.e. the deposition in the marine boundary layer in high wind events is controlled not only by the "dry" processes but also by the "wet" scavenging. During a number of cruises conducted on board of r/v Oceania between 2008 and 2012 we collected much data which were further used to calculate sea salt source function over the Baltic Sea. Measurements were carried out using a gradient method. For this method we used a Laser Particle Counter (PMS model CSASP-100_HV) placed on one of the masts of the boat. Measurements were performed at five different levels above the sea level: 8, 11, 14, 17 and 20 meters. The vertical aerosol concentration gradient was obtained from a minimum of 4 measurement series. Thus each result consists of a 1 hour series with the average sampling time at each elevation equaling to 8 minutes. Based on the averaged vertical concentration, and using the Monin Obukhov theory, profiles of vertical sea spray fluxes in the near water layer were calculated. Using the results from those experiments the sea spray emission fluxes have been calculated for all particles of sizes at ranges from 0.5 μm to 8 μm, as well as for particles of sizes from fifteen channels of 0.5 μm width. Using these fluxes we calculated the Sea Salt Generation Function (SSGF) over the Baltic Sea. This function provides information on the emission of particles of different sizes, depending on environmental parameters. The emission of sea spray depends on the magnitude of energy lost by the wind waves in the process of their collapse. The support for this study

  9. Seeing the Fields and Forests: Application of Surface-Layer Theory and Flux-Tower Data to Calculating Vegetation Canopy Height

    NASA Astrophysics Data System (ADS)

    Pennypacker, Sam; Baldocchi, Dennis

    2016-02-01

    Canopy height is an important and dynamic site variable that affects the mass and energy exchanges between vegetation and the atmosphere. We develop a method to estimate canopy height routinely, using surface-layer theory and turbulence measurements made from a collection of flux towers. This tool is based on connecting the logarithmic wind profile generally expected in a neutral surface layer with direct measurements of friction velocity and assumptions about canopy height's relationships with zero-plane displacement and aerodynamic roughness length. Tests over a broad range of canopy types and heights find that calculated values are in good agreement with direct measurements of canopy height, including in a heterogeneous landscape. Based on the various uncertainties associated with our starting assumptions about canopy micrometeorology, we present a blueprint for future work that is necessary for expanding and improving these initial calculations.

  10. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Yi; Zhang, Meigen; Liu, Zirui; Wang, Lili; Wang, Pucai; Xia, Xiangao; Tao, Minghui; Zhu, Lingyun

    2016-04-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model(WRF-Chem). The numerical experiments are performed for the period of 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred, with the simulated maximum hourly surface PM2.5 concentration of ~600 μg m-3, minimum atmospheric visibility of ~0.3 km, and 10-100 hours of simulated hourly surface PM2.5 concentration above 300 μg m-3 over NCP. A comparison of model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth reasonably well. Analysis of model results with and without aerosol feedback shows that during the fog-haze event aerosols lead to a significant negative radiative forcing of ~20 to ~140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables with maximum changes during 09:00-18:00 local time (LT) over urban Beijing and Tianjin and south Hebei: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa, while RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10 %) and the atmosphere boundary layer height decreases by 40-200 m (5-30 %) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere during 09:00-18:00, 10-15 January, compared to the surface PM2

  11. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Zhang, M.; Liu, Z.; Wang, L.; Wang, P.; Xia, X.; Tao, M.

    2015-01-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model (WRF-Chem). The numerical experiments are performed for the period 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred. Comparison of the model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth. Comparison of modeling results in the presence and absence of aerosol feedback during the fog-haze event shows that aerosols lead to a significant negative radiative forcing of -20 to -140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables of which the maximum changes occur during 09:00-18:00 LT over urban Beijing and Tianjin, and south Hebei Province: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa while the RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10%) and the atmosphere boundary layer height decreases by 40-200 m (5-30%) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere, during 09:00-18:00, 10-15 January, compared to the surface PM2.5 concentration from the model results without aerosol feedback, the average surface PM2.5 concentration increases by 10-50 μg m-3 (2-30%) over Beijing, Tianjin, and south Hebei province and the maximum increase of

  12. Modeling the feedback between aerosol and meteorological variables in the atmospheric boundary layer during a severe fog-haze event over the North China Plain

    NASA Astrophysics Data System (ADS)

    Gao, Y.; Zhang, M.; Liu, Z.; Wang, L.; Wang, P.; Xia, X.; Tao, M.; Zhu, L.

    2015-04-01

    The feedback between aerosol and meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) is analyzed by conducting numerical experiments with and without the aerosol direct and indirect effects via a coupled meteorology and aerosol/chemistry model (WRF-Chem). The numerical experiments are performed for the period of 2-26 January 2013, during which a severe fog-haze event (10-15 January 2013) occurred, with the simulated maximum hourly surface PM2.5 concentration of ~600 ug m-3, minimum atmospheric visibility of ~0.3 km, and 10-100 hours of simulated hourly surface PM2.5 concentration above 300 ug m-3 over NCP. A comparison of model results with aerosol feedback against observations indicates that the model can reproduce the spatial and temporal characteristics of temperature, relative humidity (RH), wind, surface PM2.5 concentration, atmospheric visibility, and aerosol optical depth reasonably well. Analysis of model results with and without aerosol feedback shows that during the fog-haze event aerosols lead to a significant negative radiative forcing of -20 to -140 W m-2 at the surface and a large positive radiative forcing of 20-120 W m-2 in the atmosphere and induce significant changes in meteorological variables with maximum changes during 09:00-18:00 local time (LT) over urban Beijing and Tianjin and south Hebei: the temperature decreases by 0.8-2.8 °C at the surface and increases by 0.1-0.5 °C at around 925 hPa, while RH increases by about 4-12% at the surface and decreases by 1-6% at around 925 hPa. As a result, the aerosol-induced equivalent potential temperature profile change shows that the atmosphere is much more stable and thus the surface wind speed decreases by up to 0.3 m s-1 (10%) and the atmosphere boundary layer height decreases by 40-200 m (5-30%) during the daytime of this severe fog-haze event. Owing to this more stable atmosphere during 09:00-18:00, 10-15~January, compared to the surface PM2

  13. The impact of a boundary layer height formulation on the GEOS-5 model climate

    NASA Astrophysics Data System (ADS)

    McGrath-Spangler, E. L.

    2016-04-01

    Planetary boundary layer (PBL) processes are important for the estimation of surface-atmosphere exchanges that impact global climate. One way of characterizing the strength of these processes is the PBL depth. In the Goddard Earth Observing System (GEOS-5) atmospheric general circulation model, the PBL depth is also used in calculating the turbulent length scale, which, in turn, is used in estimating the turbulence and vertical mixing within the model. Therefore, changing the PBL depth definition directly affects the model climate. This study evaluates the climatological model response of two long-term simulations using different PBL depth definitions. The first definition is based on a bulk Richardson number; the second uses a combination of the same bulk Richardson number definition over land plus a definition based on the turbulent eddy diffusion coefficient over water. The two simulations produce different spatiotemporal patterns of temperature, specific humidity, and wind speed related to the differences in turbulence. The largest differences, as expected, are present over water. Due to differences in atmospheric stability, the relationship between the two PBL depth estimates differ among the majority of the oceans and off the west coasts of continents, affecting the climatic response. Due to its optimization of the climatic response while maintaining a realistic diurnal cycle of PBL depth, the mixed PBL depth configuration is preferred.

  14. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site.

    PubMed

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (zi), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime zi from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the zi and the fine fraction (0.3-0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality.

  15. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site.

    PubMed

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (zi), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime zi from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the zi and the fine fraction (0.3-0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality. PMID:25105753

  16. Airborne measurements of hygroscopicity and mixing state of aerosols in the planetary boundary layer during the PEGASOS campaigns

    NASA Astrophysics Data System (ADS)

    Rosati, Bernadette; Weingartner, Ernest; Gysel, Martin; Rubach, Florian; Mentel, Thomas; Baltensperger, Urs

    2014-05-01

    Aerosols interact directly with the incident solar radiation by scattering or absorbing the light. The optical properties of an aerosol particle can strongly be altered at enhanced relative humidity (RH). Depending on the particle's chemical composition, it can experience hygroscopic growth, leading to a change in size and index of refraction compared to the dry particle (Zieger et al., 2011). Besides, aerosols can exist in different mixing states which are usually divided into internal and external mixtures. If all particles of a certain size have the same chemical composition, they are described as internally mixed, whereas if particles of equal size have different chemical composition, they are defined as externally mixed. Depending on the mixture the hygroscopic behavior will change: internally mixed aerosols will grow uniformly with increasing RH, while the different substances in external mixtures will experience different growing behaviors leading to a mode-splitting or broadened size distribution. Laboratory studies are commonly performed at dry conditions but it is known that temperature and RH as well as chemical composition are changing with altitude (Morgan et al., 2010). This further leads to the conclusion that the in-situ measurements of optical properties at different heights are crucial for climate forcing calculations. Within the Pan-European Gas-Aerosols-climate interaction Study (PEGASOS) the white- light humidified optical particle spectrometer (WHOPS) was developed and installed on the Zeppelin to investigate changes of light scattering with regard to water uptake and altitude. This instrument firstly selects a dry monodisperse aerosol by its electrical mobility and then exposes it to a well-defined RH (typically 95%). Alternately, the dry and humidified particles are measured in a white-light optical particle spectrometer (WELAS). In this way it is possible to infer the effective index of refraction of the dry particles, their hygroscopic

  17. Lidar Observations of Stratospheric Aerosol Layer After the Mt. Pinatubo Volcanic Eruption

    NASA Technical Reports Server (NTRS)

    Nagai, Tomohiro; Uchino, Osamu; Fujimoto, Toshifumi

    1992-01-01

    The volcano Mt. Pinatubo located on the Luzon Island, Philippines, had explosively erupted on June 15, 1991. The volcanic eruptions such as volcanic ash, SO2 and H2O reached into the stratosphere over 30 km altitude by the NOAA-11 satellite observation and this is considered one of the biggest volcanic eruptions in this century. A grandiose volcanic eruption influences the atmosphere seriously and causes many climatic effects globally. There had been many impacts on radiation, atmospheric temperature and stratospheric ozone after some past volcanic eruptions. The main cause of volcanic influence depends on stratospheric aerosol, that stay long enough to change climate and other meteorological conditions. Therefore it is very important to watch stratospheric aerosol layers carefully and continuously. Standing on this respect, we do not only continue stratospheric aerosol observation at Tsukuba but also have urgently developed another lidar observational point at Naha in Okinawa Island. This observational station could be thought valuable since there is no lidar observational station in this latitudinal zone and it is much nearer to Mt. Pinatubo. Especially, there is advantage to link up these two stations on studying the transportation mechanism in the stratosphere. In this paper, we present the results of lidar observations at Tsukuba and Naha by lidar systems with Nd:YAG laser.

  18. Effect of aerosol vertical distribution on aerosol-radiation interaction: A theoretical prospect.

    PubMed

    Mishra, Amit Kumar; Koren, Ilan; Rudich, Yinon

    2015-10-01

    This study presents a theoretical investigation of the effect of the aerosol vertical distribution on the aerosol radiative effect (ARE). Four aerosol composition models (dust, polluted dust, pollution and pure scattering aerosols) with varying aerosol vertical profiles are incorporated into a radiative transfer model. The simulations show interesting spectral dependence of the ARE on the aerosol layer height. ARE increases with the aerosol layer height in the ultraviolet (UV: 0.25-0.42 μm) and thermal-infrared (TH-IR: 4.0-20.0 μm) regions, whereas it decreases in the visible-near infrared (VIS-NIR: 0.42-4.0 μm) region. Changes in the ARE with aerosol layer height are associated with different dominant processes for each spectral region. The combination of molecular (Rayleigh) scattering and aerosol absorption is the key process in the UV region, whereas aerosol (Mie) scattering and atmospheric gaseous absorption are key players in the VIS-NIR region. The longwave emission fluxes are controlled by the environmental temperature at the aerosol layer level. ARE shows maximum sensitivity to the aerosol layer height in the TH-IR region, followed by the UV and VIS-NIR regions. These changes are significant even in relatively low aerosol loading cases (aerosol optical depth ∼0.2-0.3). Dust aerosols are the most sensitive to altitude followed by polluted dust and pollution in all three different wavelength regions. Differences in the sensitivity of the aerosol type are explained by the relative strength of their spectral absorption/scattering properties. The role of surface reflectivity on the overall altitude dependency is shown to be important in the VIS-NIR and UV regions, whereas it is insensitive in the TH-IR region. Our results indicate that the vertical distribution of water vapor with respect to the aerosol layer is an important factor in the ARE estimations. Therefore, improved estimations of the water vapor profiles are needed for the further reduction in

  19. Effect of aerosol vertical distribution on aerosol-radiation interaction: A theoretical prospect.

    PubMed

    Mishra, Amit Kumar; Koren, Ilan; Rudich, Yinon

    2015-10-01

    This study presents a theoretical investigation of the effect of the aerosol vertical distribution on the aerosol radiative effect (ARE). Four aerosol composition models (dust, polluted dust, pollution and pure scattering aerosols) with varying aerosol vertical profiles are incorporated into a radiative transfer model. The simulations show interesting spectral dependence of the ARE on the aerosol layer height. ARE increases with the aerosol layer height in the ultraviolet (UV: 0.25-0.42 μm) and thermal-infrared (TH-IR: 4.0-20.0 μm) regions, whereas it decreases in the visible-near infrared (VIS-NIR: 0.42-4.0 μm) region. Changes in the ARE with aerosol layer height are associated with different dominant processes for each spectral region. The combination of molecular (Rayleigh) scattering and aerosol absorption is the key process in the UV region, whereas aerosol (Mie) scattering and atmospheric gaseous absorption are key players in the VIS-NIR region. The longwave emission fluxes are controlled by the environmental temperature at the aerosol layer level. ARE shows maximum sensitivity to the aerosol layer height in the TH-IR region, followed by the UV and VIS-NIR regions. These changes are significant even in relatively low aerosol loading cases (aerosol optical depth ∼0.2-0.3). Dust aerosols are the most sensitive to altitude followed by polluted dust and pollution in all three different wavelength regions. Differences in the sensitivity of the aerosol type are explained by the relative strength of their spectral absorption/scattering properties. The role of surface reflectivity on the overall altitude dependency is shown to be important in the VIS-NIR and UV regions, whereas it is insensitive in the TH-IR region. Our results indicate that the vertical distribution of water vapor with respect to the aerosol layer is an important factor in the ARE estimations. Therefore, improved estimations of the water vapor profiles are needed for the further reduction in

  20. Long Range Transport of Amazon Aerosol in the Free Troposphere: Influence of Amazon Combustion Aerosol on CCN in the Pacific Marine Boundary Layer

    NASA Astrophysics Data System (ADS)

    Howell, S. G.; Clarke, A. D.; Freitag, S.; Kapustin, V.; Hudson, J.; Campos, T.; Pollack, I. B.; Heizer, C. G.; Weinheimer, A. J.

    2008-12-01

    The Pacific Atmosphere Sulfur Experiment (PASE, Sept. 2007) on the NCAR C-130 aircraft was based in the Equatorial Pacific to explore the remote marine sulfur cycle. We investigated sources that control particle number and cloud condensation nuclei, CCN, in the clean marine boundary layer (MBL). Earlier studies here demonstrated particle number above the MBL was dominated by natural production of new volatile particles in cloud outflow. However, during PASE we also found coated refractory aerosol (non-volatile at 350C) aloft were linearly related to ozone concentrations and were effective CCN at 0.2% supersaturation. These aerosol had larger diameters than naturally produced volatile aerosol and trajectory analysis traced them back to deep convection in biomass burning haze over the Amazon basin over 10,000km away. These refractory soot and/or organic aerosol appear to be detrained from deep convective clouds after the near- source scavenging of larger sizes that dominate the smoke/haze aerosol mass. Following transport and once mixed into MBL they were found to account for as much as 30% of the CCN at the value of 0.2%S (a typical value for small trade-wind cumulus clouds). Hence, cloud-scavenged combustion derived aerosol, too small to be detectable optically in satellite plumes, appears to provide seed nuclei for CCN in the remote marine boundary layer. This acts over hemispheric scales for this region and presumably elsewhere. Hence; various mechanisms including convective scavenging, long range transport, particle production aloft, entrainment into the MBL, boundary layer nucleation and sea-salt production all need to be considered in modeling the MBL CCN population.

  1. Resolving Organized Aerosol Structures (Rolls and Layers) with Airborne Fast Mobility Particle Sizer (FMPS) During MILAGRO/INTEX Campaign

    NASA Astrophysics Data System (ADS)

    Kapustin, V.; Clarke, A.; Zhou, J.; Howell, S.; Shinozuka, Y.; Brekhovskikh, V.; McNaughton, C.

    2007-12-01

    The Hawaii Group for Environmental Aerosol Research [http://www.soest.hawaii.edu/HIGEAR] deployed a wide range of aerosol instrumentation aboard the C-130 and the NASA DC-8 as part of MILAGRO/INTEX. These were designed to provide rapid information on aerosol composition, state of mixing (internal or external), spectral optical properties (scattering and absorption), the humidity dependence of light scattering-f(RH), and the role of condensed species in changing the absorption properties of black carbon (BC) and inferred properties of organic carbon (OC). These measurements included size distributions from about 7 nm up to about 10,000 nm and their volatility at 150, 300 and 400 C; size selected response to heating (volatility) to resolve the state of mixing of the aerosol; continuous measurements of the light scattering and absorption at 3 wavelengths; measurements of the f(RH). We also flew the first airborne deployment of the new Fast Mobility Particle Sizer (FMPS, TSI Inc.) that provided information on rapid (1Hz) size variations in the Aitken mode. This revealed small scale structure of the aerosol and allowed us to examine size distributions varying over space and time associated with mixing processes previously unresolved etc. Rapid measurements during profiles also revealed variations in size over shallow layers. Other dynamic processes included rapid size distribution measurements within orographically induced aerosol layers and size distribution evolution of the nanoparticles formed by nucleation (C-130 flights 5, 6 and 9). Evidence for fluctuations induced by underlying changes in topography was also detected. These measurements also frequently revealed the aerosol variability in the presence of boundary layer rolls aligned along the wind in the Marine Boundary Layer (Gulf region) both with and without visible cloud streets (DC-8 flight 4 and C-130 flight 7). This organized convection over 1-2 km scales influences the mixing processes (entrainment, RH

  2. The Influence of High Aerosol Concentration on Atmospheric Boundary Layer Temperature Stratification

    SciTech Connect

    Khaykin, M.N.; Kadygrove, E.N.; Golitsyn, G.S.

    2005-03-18

    Investigations of the changing in the atmospheric boundary layer (ABL) radiation balance as cased by natural and anthropogenic reasons is an important topic of the U.S. Department of Energy's Atmospheric Radiation Measurement (ARM) program. The influence of aerosol on temperature stratification of ABL while its concentration was extremely high within a long period of time was studied experimentally. The case was observed in Moscow region (Russia) with the transport of combustion products from peat-bog and forest fires in July-September, 2002. At this time the visibility was some times at about 100-300 m. Aerosol concentration measured by Moscow University Observatory and A.M. Obukhov Institute of Atmospheric Physics field station in Zvenigorod (55.7 N; 36.6 E) for several days was in 50-100 times more than background one (Gorchakov at al 2003). The high aerosol concentration can change the radiation balance at ABL, and so to change thermal stratification in ABL above the mega lopolis. For the analysis the data were used of synchronous measurements by MTP-5 (Microwave Temperature Profiler operating at wavelength 5 mm) in two locations, namely: downtown Moscow and country-side which is 50 km apart to the West (Zvenigorod station). (Kadygrov and Pick 1998; Westwater at al 1999; Kadygrov at al 2002). Zvenigorod station is located in strongly continental climate zone which is in between of the climates of ARM sites (NSANorth Slope of Alaska and SGP-Southern Great Plains). The town of Zvenigorod has little industry, small traffic volume and topography conductive to a good air ventilation of the town. For these reasons Zvenigorod can be considered as an undisturbed rural site. For the analysis some days were chosen with close meteorological parameters (average temperature, humidity, wind, pressure and cloud form) but strongly differing in aerosol concentration level.

  3. Impacts of sources and aging on submicrometer aerosol properties in the marine boundary layer across the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Quinn, P. K.; Bates, T. S.; Coffman, D.; Onasch, T. B.; Worsnop, D.; Baynard, T.; de Gouw, J. A.; Goldan, P. D.; Kuster, W. C.; Williams, E.; Roberts, J. M.; Lerner, B.; Stohl, A.; Pettersson, A.; Lovejoy, E. R.

    2006-12-01

    Measurements were made on board the NOAA RV Ronald H. Brown during the second New England Air Quality Study (NEAQS 2004) to determine the source of the aerosol in the region and how sources and aging processes affect submicrometer aerosol chemical composition and optical properties. Using the Lagrangian particle dispersion model FLEXPART in combination with gas phase tracer compounds, local (urban), regional (NE U.S. urban corridor of Washington, D.C.; New York; and Boston), and distant (midwest industries and North American forest fires) sources were identified. Submicrometer aerosol measured near the source region (Boston Harbor) had a molar equivalence ratio near one with respect to NH4+, NO3-, and SO4=, had a large mass fraction of particulate organic matter (POM) relative to SO4=, and had relatively unoxidized POM. As distance from the source region increased, the submicrometer aerosol measured in the marine boundary layer became more acidic and had a lower POM mass fraction, and the POM became more oxidized. The relative humidity dependence of light extinction reflected the change in aerosol composition being lower for the near-source aerosol and higher for the more processed aerosol. A factor analysis performed on a combined data set of aerosol and gas phase parameters showed that the POM measured during the experiment was predominantly of secondary anthropogenic origin.

  4. An aerosol climatology for the Jungfraujoch, Part 1: Criteria for cloud presence and boundary layer influence

    NASA Astrophysics Data System (ADS)

    Herrmann, Erik; Weingartner, Ernest; Gysel, Martin; Bukowiecki, Nicolas; Hammer, Emanuel; Collaud Coen, Martine; Conen, Franz; Vuilleumier, Laurent; Baltensperger, Urs

    2014-05-01

    The high alpine research station at the Jungfraujoch in Switzerland is located at 3580 m asl. Depending on meteorological conditions, the station is in the planetary boundary layer or in the free troposphere; and often it is inside clouds. In one location, it is thus possible to study aerosols under very different conditions. These possibilities have been recognized early on, with aerosol measurements starting in 1995. Over the years, the instrumentation has been extended significantly, today including various measurements of aerosol optical properties (nephelometer, aethalometer, MAAP) as well as aerosol size distribution (SMPS, OPC, APS). Additionally, the station regularly hosts campaigns (e.g. CLACE) with a multitude of additional devices, mostly focusing on new particle formation, cloud condensation nuclei, and ice nuclei. However, there are no continuously operated direct measurements to determine whether the station is in the clouds or not, whether it is in the PBL or the free troposphere. As these are essential parameters to describe the aerosol observed at the station, we present approaches to describe them based on the observations available to us. The intuitive choices to look at in terms of clouds are relative humidity and dew point. When comparing dew point and ambient temperature, a clear criterion to identify clouds can be easily deducted. However, the determination of "no clouds" is more ambiguous. Based on longwave radiation measurements performed routinely at the site, it is possible to calculate the sky temperature, i.e. the temperature at the point of origin of the radiation. When within a cloud, the sky temperature should be identical or at least close to ambient temperature. The comparison of sky and ambient temperature shows two clear clusters which can be interpreted as "cloud" and "no cloud". One has to note that in case of inversion or clouds shortly above the research station, this approach will produce false positives. However, combining

  5. Aerosol transport and dispersion measurements in the near surface boundary layer

    NASA Astrophysics Data System (ADS)

    Hiscox, April Lynn

    The studies presented in this dissertation present new techniques for measuring aerosols in the atmosphere, and the application of these techniques to three different aerosol sources. A methodology for measuring dispersion parameters based on lidar images, which can be used as an efficient way to remotely monitor time variations of plume dispersion parameters, is presented. Lidar images of a smoke plume cross-section over a forest canopy during nighttime conditions are analyzed to estimate vertical dispersion parameters and vertical meander of the plume centerline in the near field. Dispersion parameters 60 meters downwind are found to have a median value of 2.31 meters. Measurements of these parameters have not previously been made outside the restraints of a wind tunnel experiment. A second technique to measure in-plume concentrations based on single wavelength lidar images is also presented. A field study of aerial spray movement and dispersion was used to determine in-plume spray concentrations of very fine droplets applied during calm, stable atmospheric conditions. Supporting meteorology and air turbulence measurements were made simultaneously with 3-D sonic anemometers. The amount of spray material remaining in the air decreased rapidly for 1--2 minutes, and thereafter remained nearly constant and drifted as a definable plume with the slight air currents. Finally, these two techniques are applied to measure near-field spatial dynamics, spread and concentrations of dust plumes emitted during tilling and harvesting of an irrigated cotton field. Combined lidar images are used to form three-dimensional plumes. Plume dynamics and suspended aerosol concentrations are found. Dust plume dynamics varied with atmospheric stability. In particular, plume maximum height was significantly lower during stable conditions. Plume tracking indicated little change in plume cross-sectional area with height under unstable conditions and plume movement depended on wind speed and

  6. Observed perturbations of the Earth's Radiation Budget - A response to the El Chichon stratospheric aerosol layer?

    NASA Technical Reports Server (NTRS)

    Ardanuy, P. E.; Kyle, H. L.

    1986-01-01

    The Earth Radiation Budget experiment, launched aboard the Nimbus-7 polar-orbiting spacecraft in late 1978, has now taken over seven years of measurements. The dataset, which is global in coverage, consists of the individual components of the earth's radiation budget, including longwave emission, net radiation, and both total and near-infrared albedos. Starting some six months after the 1982 eruption of the El Chichon volcano, substantial long-lived positive shortwave irradiance anomalies were observed by the experiment in both the northern and southern polar regions. Analysis of the morphology of this phenomena indicates that the cause is the global stratospheric aerosol layer which formed from the cloud of volcanic effluents. There was little change in the emitted longwave in the polar regions. At the north pole the largest anomaly was in the near-infrared, but at the south pole the near UV-visible anomaly was larger. Assuming an exponential decay, the time constant for the north polar, near-infrared anomaly was 1.2 years. At mid- and low latitudes the effect of the El Chichon aerosol layer could not be separated from the strong reflected-shortwave and emitted-longwave perturbations issuing from the El Nino/Southern Oscillation event of 1982-83.

  7. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, Michael; Muñoz-Esparza, Domingo; Chouza, Fernando; Reitebuch, Oliver; Knoth, Oswald; Haarig, Moritz; Ansmann, Albert; Tegen, Ina

    2016-04-01

    Large eddy simulations (LESs) with ASAM (All Scale Atmospheric Model) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude potential temperature perturbations. This method is now also validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE (Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment) field campaign is used for both model initialization and comparisons. Several sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" or when the turbulent marine boundary layer flow is replaced by laminar winds. Additional simulation cases deal with modified surface characteristics and their impacts on the simulation results. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ≈ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with lidar data show similarities in the downwind vertical wind structure and accurately reproduces the development of the daytime convective boundary layer measured by the Raman lidar.

  8. Interaction between the aerosol direct effect in the lower troposphere and the planetary boundary layer depth

    NASA Astrophysics Data System (ADS)

    Sawyer, Virginia Ruth

    The planetary boundary layer (PBL) limits the vertical mixing of aerosol emitted to the lower troposphere. The PBL depth and its change over time affect weather, surface air quality and radiative forcing. While model simulations have suggested that the column optical properties of aerosol are associated with changes in the PBL depth in turn, there are few long-term measurements of PBL depth with which to validate the theory. Of the existing methods to detect the PBL depth from atmospheric profiles, many require supporting information from multiple instruments or cannot adapt to changing atmospheric conditions. This study combines two common methods for PBL depth detection (wavelet covariance and iterative curve-fitting) in order to produce more reliable PBL depths for micropulse lidar backscatter (MPL). The combined algorithm is also flexible enough to use with radiosonde and atmospheric emitted radiance interferometer (AERI) data. PBL depth retrievals from these three instruments collected at the Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) site are compared to one another to show the robustness of the algorithm. The comparisons were made for different times of day, four seasons, and variable sky conditions. While considerable uncertainties exist in PBL detection using all three types of measurements, the agreement among the PBL products is promising, and the different measurements have complementary advantages. The best agreement in the seasonal cycle occurs in winter, and the best agreement in the diurnal cycle when the boundary-layer regime is mature and changes slowly. PBL depths from instruments with higher temporal resolution (MPL and AERI) are of comparable accuracy to radiosonde-derived PBL depths. The new PBL depth measurements for SGP are compared to MPL-derived PBL depths from a multiyear lidar deployment at the Hefei Radiation Observatory (HeRO), and the column aerosol optical depth (AOD) for each site is considered. A one

  9. 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].

  10. Characterizing the formation of organic layers on the surface of inorganic/aqueous aerosols by Raman spectroscopy.

    PubMed

    Buajarern, Jariya; Mitchem, Laura; Reid, Jonathan P

    2007-11-22

    We demonstrate that nonlinear Raman spectroscopy coupled with aerosol optical tweezers can be used to probe the evolving phase partitioning in mixed organic/inorganic/aqueous aerosol droplets that adopt a core-shell structure in which the aqueous phase is coated in an organic layer. Specifically, we demonstrate that the characteristic fingerprint of wavelengths at which stimulated Raman scattering is observed can be used to assess the phase behavior of multiphase decane/aqueous sodium chloride droplets. Decane is observed to form a layer on the surface of the core aqueous droplet, and from the spectroscopic signature the aqueous core size can be determined with nanometer accuracy and the thickness of the decane layer with an accuracy of +/-8 nm. Further, the presence of the organic layer is observed to reduce the rate at which water evaporates from the core of the droplet with an increasing rate of evaporation observed with diminishing layer thickness.

  11. Characterizing the formation of organic layers on the surface of inorganic/aqueous aerosols by Raman spectroscopy.

    PubMed

    Buajarern, Jariya; Mitchem, Laura; Reid, Jonathan P

    2007-11-22

    We demonstrate that nonlinear Raman spectroscopy coupled with aerosol optical tweezers can be used to probe the evolving phase partitioning in mixed organic/inorganic/aqueous aerosol droplets that adopt a core-shell structure in which the aqueous phase is coated in an organic layer. Specifically, we demonstrate that the characteristic fingerprint of wavelengths at which stimulated Raman scattering is observed can be used to assess the phase behavior of multiphase decane/aqueous sodium chloride droplets. Decane is observed to form a layer on the surface of the core aqueous droplet, and from the spectroscopic signature the aqueous core size can be determined with nanometer accuracy and the thickness of the decane layer with an accuracy of +/-8 nm. Further, the presence of the organic layer is observed to reduce the rate at which water evaporates from the core of the droplet with an increasing rate of evaporation observed with diminishing layer thickness. PMID:17958403

  12. Response of some ionospheric parameters to geomagnetic disturbances at heights below the F2-layer maximum in September and April 2005

    NASA Astrophysics Data System (ADS)

    Kushnarenko, G. P.; Kuznetsova, G. M.; Ratovskii, K. G.; Kolpakova, O. E.

    2012-05-01

    An analysis of ionospheric data obtained during geomagnetic disturbances in April and September 2005 is performed in order to obtain information on the behavior of some ionospheric parameters at heights of the F1 layer. The results of measurements by an Irkutsk digisonde at hourly and 5- and 15-min time intervals were used. It is shown that in September all parameters very actively responded to geomagnetic disturbances in short measurement time intervals. It is also shown that the electron concentration behaves more stable at lower heights of the F1 layer both during strong and moderate disturbances.

  13. Characterizing the Asian Tropopause Aerosol Layer (ATAL) Using Satellite Observations, Balloon Measurements and a Chemical Transport Model

    NASA Technical Reports Server (NTRS)

    Fairlie, T. D.; Vernier, J.-P.; Liu, H.; Deshler, T.; Natarajan, M.; Bedka, K.; Wegner, T.; Baker, N.; Gadhavi, H.; Ratnam, M. V.; Jayaraman, A.; Pandit, A.; Raj, A.; Kumar, H.; Kumar, S.; Singh, A.; Stenchikov, G.; Wienhold, F.; Bian, J.

    2016-01-01

    Satellite observations and numerical modeling studies have demonstrated that the Asian Summer Monsoon (ASM) provide a conduit for gas-phase pollutants in south Asia to reach the lower stratosphere. Now, observations from the CALIPSO satellite have revealed the Asian Tropopause Aerosol Layer (ATAL), a summertime accumulation of aerosols in the upper troposphere and lower stratosphere (UTLS), associated with the ASM anticyclone. The ATAL has potential implications for regional cloud properties, climate, and chemical processes in the UTLS. Here, we show in situ measurements from balloon-borne instruments, aircraft, and satellite observations, together with trajectory and chemical transport model (CTM) simulations to explore the origin, composition, physical, and optical properties of aerosols in the ATAL. In particular, we show balloon-data from our BATAL-2015 field campaign to India and Saudi Arabia in summer 2015, which includes in situ backscatter measurements from COBALD instruments, and the first observations of size and volatility of aerosols in the ATAL layer using optical particle counters (OPCs). Back trajectory calculations initialized from CALIPSO observations point to deep convection over North India as a principal source of ATAL aerosols. Available aircraft observations suggest significant sulfur and carbonaceous components to the ATAL, which is supported by simulations using the GEOS-Chem CTM. Source elimination studies conducted with the GEOS-Chem indicate that ATAL aerosols originate primary from south Asian sources, in contrast with some earlier studies.

  14. Global model of the F2 layer peak height for low solar activity based on GPS radio-occultation data

    NASA Astrophysics Data System (ADS)

    Shubin, V. N.; Karpachev, A. T.; Tsybulya, K. G.

    2013-11-01

    We propose a global median model SMF2 (Satellite Model of the F2 layer) of the ionospheric F2-layer height maximum (hmF2), based on GPS radio-occultation data for low solar activity periods (F10.7A<80). The model utilizes data provided by GPS receivers onboard satellites CHAMP (~100,000 hmF2 values), GRACE (~70,000) and COSMIC (~2,000,000). The data were preprocessed to remove cases where the absolute maximum of the electron density lies outside the F2 region. Ground-based ionospheric sounding data were used for comparison and validation. Spatial dependence of hmF2 is modeled by a Legendre-function expansion. Temporal dependence, as a function of Universal Time (UT), is described by a Fourier expansion. Inputs of the model are: geographical coordinates, month and F10.7A solar activity index. The model is designed for quiet geomagnetic conditions (Kр=1-2), typical for low solar activity. SMF2 agrees well with the International Reference Ionosphere model (IRI) in those regions, where the ground-based ionosonde network is dense. Maximal difference between the models is found in the equatorial belt, over the oceans and the polar caps. Standard deviations of the radio-occultation and Digisonde data from the predicted SMF2 median are 10-16 km for all seasons, against 13-29 km for IRI-2012. Average relative deviations are 3-4 times less than for IRI, 3-4% against 9-12%. Therefore, the proposed hmF2 model is more accurate than IRI-2012.

  15. Observations of summertime NO fluxes and boundary-layer height at the South Pole during ISCAT 2000 using scalar similarity

    NASA Astrophysics Data System (ADS)

    Oncley, S. P.; Buhr, M.; Lenschow, D. H.; Davis, D.; Semmer, S. R.

    2004-10-01

    Eddy-covariance heat flux as well as temperature and NO concentration gradients were measured during the ISCAT 2000 (Investigation of Sulfur Chemistry in the Antarctic Troposphere) field study at the South Pole (SP). These quantities allowed for the use of the modified Bowen ratio technique to estimate the surface flux of NO and, from photochemical considerations, the NOx flux. The meteorological measurement package employed in these experiments consisted of sonic anemometer/thermometers (ATI K-probes) and temperature/humidity sensors (NCAR). A chemiluminescent analyzer housed in an environmental enclosure was used to measure NO. All sampling took place on a 22 m meteorological tower. The time period over which flux measurements were recorded was 26 November through 30 November 2000. The average value of the NO flux was estimated to be 2.6 ± 0.3 ×108 moleccm-2s-1; whereas, for NOx the average flux was 3.9 ± 0.4 ×108 moleccm-2s-1. To assist in the interpretation of these results, the height of the atmospheric boundary-layer at the SP from 23 November to 28 December 2000 was also estimated.

  16. Aerosol dynamics in the equatorial Pacific Marine boundary layer: Microphysics, diurnal cycles and entertainment

    SciTech Connect

    Clarke, A D; Litchy, M; Li, Z

    1996-04-01

    During July-August of 1994 the authors measured the size resolved physiochemical properties of aerosol particles at Christmas Island in the equatorial Pacific. In spite of rapid diurnal conversion of dimethylsulfide (DMS) to sulfur dioxide (SO{sub 2}) the authors found no evidence for new particle production in the marine boundary layer (MBL) and more than 95% of all particles were consistently larger than 0.02{mu}m diameter, indicating an aged aerosol number (size-distribution) was bimodal with peaks near 0.05{mu}m and 0.2{mu}m particle diameter (D{sub p}) and had a cloud-processed intermode minimum at about 0.09{mu}m that varied in phase with diurnal changes in ozone concentration. This suggests that the number distribution for condensation nuclei (CN) and cloud condensation (CCN) was maintained by a quasiequilibrium between entrainment (estimated to be 0.6{+-}0.2 cm s{sup {minus}1}) from sources aloft and processes in the MBL. This implies a replenishment timescale for nuclei of about 2 and 4 days for this region. The stability of the distribution and the 0.09{mu}m cloud processed minima suggests trade winds cumulus supersaturations near 0.35% and updrafts near 1 m s{sup {minus}1}. 17 refs., 4 fig., 1 tab.

  17. Elevated aerosol layers modify the O2-O2 absorption measured by ground-based MAX-DOAS

    NASA Astrophysics Data System (ADS)

    Ortega, Ivan; Berg, Larry K.; Ferrare, Richard A.; Hair, Johnathan W.; Hostetler, Chris A.; Volkamer, Rainer

    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 Aerosol 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 0.53aerosol layers, unless accounted for, can cause negative bias in the simulated O4 dSCDs that can explain CFO4. The air density and aerosol profile aloft needs to be taken into account when interpreting the O4 from ground-based MAX-DOAS. Opportunities to identify and better characterize these elevated layers are also discussed.

  18. The relationship of boundary layer clouds in the tropical southeast Atlantic to absorbing aerosols, meteorology and climate change

    NASA Astrophysics Data System (ADS)

    Zuidema, P.; Adebiyi, A. A.; Ramajiguru, L.

    2015-12-01

    Ascension Island, a remote island located in the middle of the Atlantic Ocean within the trade-wind region oat 8S, 14.5W, experiences the outflow of biomass-burning aerosols from continental Africa, over 2000 km away, from July through November, peaking in August and September. The shortwave-absorbing free-tropospheric aerosols, located in a region of high solar irradiance, provide a climate warming that is poorly represented in global aerosol climate models. The low clouds can respond to the smoke layer in myriad possible ways that are not yet well-documented. The shortwave-warming can stabilize the free-troposphere, enhancing the low cloud fraction. The deepening boundary layer and subsiding smoke layer also increase the likelihood of aerosol-cloud microphysical interactions. Interest in this climate regime is supporting an observational strategy of a year-long DOE ARM Mobile Facility deployment to Ascension (Layered Atlantic Smoke Interactions with Clouds, or LASIC), and an NSF aircraft campaign (ObservatioNs of Fire's Impact on the southeast atlantic REgion, or ONFIRE) based on Sao Tome Island. These campaigns will be integrated with NASA, UK and African activities sharing similar goals based further south in Namibia. Initial analysis is distinguishing meteorology from aerosol impacts on the boundary layer cloud fields. The forward trajectories of emissions from over 24,000 fire sources on continental Africa show that a free-tropospheric jet can advect aerosols to above Ascension island in just one-two days. The fast transport time encourages retention of signatures of the fire sources, in particular the radiatively-crucial single-scattering albedo value. Thereafter, a deep land-based anticyclonic high recirculates over one-third of these trajectories back to the African continent, explaining the widespread extent of the aerosol layer. The free-tropospheric jet also reduces the mean atmospheric subsidence independently of shortwave absorption by the aerosols

  19. Lidar determination of winds by aerosol inhomogeneities: motion velocity in the planetary boundary layer.

    PubMed

    Kolev, I; Parvanov, O; Kaprielov, B

    1988-06-15

    The paper presents results from lidar measurements of wind velocity in the planetary boundary layer using correlation data processing. Two lidars are used in our experiments: a ruby lidar operating along slant paths and a YAG:Nd lidar operating for near vertical sounding used by us for the first time. On the basis of our experience the optimal sizes of aerosol inhomogeneities (30-300 m), the duration of the experiments (2-10 min), and the repetition rate of laser shots (fractions of hertz to several hertz) are determined. The results are compared to independent data obtained from anemometer measurements, theodolite- and radar-tracked pilot balloons. The range of differences is ~1-2 m/s in speed and 10-15 degrees in direction. Preliminary results from the use of lidar data to remotely sound the wind speed for various atmospheric stratifications and synoptic situations are described as well. PMID:20531786

  20. Radiative Impact of Aerosols on the Regional Boundary Layer Features in Strong and Weak Wind Conditions using WRF Modeling System

    NASA Astrophysics Data System (ADS)

    Rajagopalan, R. A.; Sharan, M.

    2015-12-01

    Atmospheric aerosol particles play a vital role in the Earth's radiative energy budget. They exert a net cooling influence on climate by directly reflecting the solar radiation to space and by modifying the shortwave reflective properties of clouds. Radiation is the main source that regulates the surface energy budget. Surface temperature and planetary boundary layer (PBL) height depends on accurate calculation of both shortwave and longwave radiation. The weakening of the ambient winds is known to influence the structure of PBL. This study examines the sensitivity of the performance of Weather Research Forecasting (WRF) ARW Model to the use of different radiation schemes [For Long wave Radiation: Rapid Radiative Transfer Model (RRTM), Eta Geophysical Fluid Dynamics Laboratory (GFDL), Goddard, New Goddard, NCAR Community Atmosphere Model (CAM 3.0), New Goddard scheme, Fu-Liou-Gu scheme and for Short wave Radiation: Dudhia scheme, Eta Geophysical Fluid Dynamics Laboratory (GFDL), NCAR Community Atmosphere Model (CAM 3.0), New Goddard scheme]. Two different simulations are conducted one for the summer (14-15 May 2009) and winter (14-15 Dec 2008) season characterized by strong and weak wind conditions over India. Comparison of surface temperatures from different schemes for different cities (New Delhi, Ahmedabad, Lucknow, Kanpur, Jaipur and Jodhpur) on 14-15 May 2009 and 14-15 Dec 2008 with those observed shows the simulation with RRTM , New Goddard, and Fu-Liou-Gu schemes are closer to the observations as compared to other schemes. The temperature simulated from all the radiation schemes have more than 0.9 correlation coefficient but the root mean square error is relatively less in summer compared to winter season. It is surmised that Fu-Liou-Gu scheme performs better in almost all the cases. The reason behind can be the greater absorption of solar and IR radiative fluxes in the atmosphere and the surface provided in Fu-Liou-Gu radiation scheme than those computed in

  1. Surface barrier height for different Al compositions and barrier layer thicknesses in AlGaN/GaN heterostructure field effect transistors

    SciTech Connect

    Goyal, Nitin Fjeldly, Tor A.; Iniguez, Benjamin

    2013-12-04

    In this paper, we present a physics based analytical model for the calculation of surface barrier height for given values of barrier layer thicknesses and Al mole fractions. An explicit expression for the two dimensional electron gas density is also developed incorporating the change in polarization charges for different Al mole fractions.

  2. Secondary organic aerosol formation of relevance to the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Cai, Xuyi

    The chlorine atom (Cl) is a potential oxidant of volatile organic compounds (VOCs) in the atmosphere and is hypothesized to lead to secondary organic aerosol (SOA) formation in coastal areas. The purpose of this dissertation is to test this hypothesis and quantify the SOA formation potentials of some representative biogenic and anthropogenic hydrocarbons when oxidized by Cl in laboratory chamber experiments. The chosen model compounds for biogenic and anthropogenic hydrocarbons in this study are three monoterpenes (alpha-pinene, beta-pinene, and d-limonene) and two aromatics (m-xylene and toluene), respectively. Results indicate that the oxidation of these monoterpenes and aromatics generates significant amounts of aerosol. The SOA yields of alpha-pinene, beta-pinene, and d-limonene obtained in this study are comparable to those when they are oxidized by ozone, by nitrate radical, and in photooxidation scenarios. For aerosol mass up to 30.0 mug m-3, their yields reach approximately 0.20, 0.20, and 0.30, respectively. The SOA yields for m-xylene and toluene are found to be in the range of 0.035 to 0.12 for aerosol concentrations up to 19 mug m-3. For d-limonene and toluene, data indicate two yield curves that depend on the initial concentration ratios of Cl precursor to hydrocarbon hydrocarbon. Zero-dimensional calculations based on these yields show that SOA formation from the five model compounds when oxidized by Cl in the marine boundary layer could be a significant source of SOA in the early morning. In addition, the mechanistic reaction pathways for Cl oxidation of alpha-pinene, beta-pinene, d-limonene, and toluene with Cl have been developed within the framework of the Caltech Atmospheric Chemistry Mechanisms (CACM). Output from the developed mechanisms is combined with an absorptive partitioning model to predict precursor decay curves and time-dependent SOA concentrations in experiments. Model calculations are able to match (in general within general +/- 50

  3. Aerosol-Jet-Printing silicone layers and electrodes for stacked dielectric elastomer actuators in one processing device

    NASA Astrophysics Data System (ADS)

    Reitelshöfer, Sebastian; Göttler, Michael; Schmidt, Philip; Treffer, Philipp; Landgraf, Maximilian; Franke, Jörg

    2016-04-01

    In this contribution we present recent findings of our efforts to qualify the so called Aerosol-Jet-Printing process as an additive manufacturing approach for stacked dielectric elastomer actuators (DEA). With the presented system we are able to print the two essential structural elements dielectric layer and electrode in one machine. The system is capable of generating RTV-2 silicone layers made of Wacker Elastosil P 7670. Therefore, two aerosol streams of both precursor components A and B are generated in parallel and mixed in one printing nozzle that is attached to a 4-axis kinematic. At maximum speed the printing of one circular Elastosil layer with a calculated thickness of 10 μm and a diameter of 1 cm takes 12 seconds while the process keeps stable for 4.5 hours allowing a quite high overall material output and the generation of numerous silicone layers. By adding a second printing nozzle and the infrastructure to generate a third aerosol, the system is also capable of printing inks with conductive particles in parallel to the silicone. We have printed a reduced graphene oxide (rGO) ink prepared in our lab to generate electrodes on VHB 4905, Elastosil foils and finally on Aerosol-Jet-Printed Elastosil layers. With rGO ink printed on Elastosil foil, layers with a 4-point measured sheet resistance as low as 4 kΩ can be realized leaving room for improving the electrode printing time, which at the moment is not as good as the quite good time-frame for printing the silicone layers. Up to now we have used the system to print a fully functional two-layer stacked DEA to demonstrate the principle of continuously 3D printing actuators.

  4. Variability of the stratospheric aerosol layer due to volcanic eruptions in the last decade: Odin-OSIRIS measurements

    NASA Astrophysics Data System (ADS)

    Bourassa, A. E.; Degenstein, D. A.

    2011-12-01

    Recently reported measurements show that an increasing trend in the stratospheric aerosol layer during the last decade can be attributed in a large part to a series of relatively minor lower stratospheric volcanic eruptions. The limb scatter measurements of the stratospheric aerosol extinction coefficient made by the OSIRIS instrument on the Odin satellite show evidence of several eruptions, both tropical and at high latitude, which have a significant impact on the stratospheric aerosol layer. The extent and duration of the stratospheric impact of these eruptions is explored in this work. The measurements, which have daily, nearly global coverage, show that these minor eruptions, particularly those in the tropics, have increased the magnitude of stratospheric aerosol optical depth by more than 5% per year at mid-latitudes. Additionally, the measurements show that a measureable increase in aerosol optical depth is observed in the tropics in the months following the eruption of two high latitude eruptions, namely Kasatochi Volcano in 2008 and Sarychev Peak in 2009.

  5. Improvements to the OMI Near-uv Aerosol Algorithm Using A-train CALIOP and AIRS Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Ahn, C.; Zhong, C.

    2014-01-01

    The height of desert dust and carbonaceous aerosols layers and, to a lesser extent, the difficulty in assessing the predominant size mode of these absorbing aerosol types, are sources of uncertainty in the retrieval of aerosol properties from near UV satellite observations. The availability of independent, near-simultaneous measurements of aerosol layer height, and aerosol-type related parameters derived from observations by other A-train sensors, makes possible the direct use of these parameters as input to the OMI (Ozone Monitoring Instrument) near UV retrieval algorithm. A monthly climatology of aerosol layer height derived from observations by the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) sensor, and real-time AIRS (Atmospheric Infrared Sounder) CO observations are used in an upgraded version of the OMI near UV aerosol algorithm. AIRS CO measurements are used as a reliable tracer of carbonaceous aerosols, which allows the identification of smoke layers in areas and times of the year where the dust-smoke differentiation is difficult in the near-UV. The use of CO measurements also enables the identification of elevated levels of boundary layer pollution undetectable by near UV observations alone. In this paper we discuss the combined use of OMI, CALIOP and AIRS observations for the characterization of aerosol properties, and show a significant improvement in OMI aerosol retrieval capabilities.

  6. A simple method to compute the change in earth-atmosphere radiative balance due to a stratospheric aerosol layer

    NASA Technical Reports Server (NTRS)

    Lenoble, J.; Tanre, D.; Deschamps, P. Y.; Herman, M.

    1982-01-01

    A computer code was developed in terms of a three-layer model for the earth-atmosphere system, using a two-stream approximation for the troposphere and stratosphere. The analysis was limited to variable atmosphere loading by solar radiation over an unperturbed section of the atmosphere. The scattering atmosphere above a Lambertian ground layer was considered in order to derive the planar albedo and the spherical albedo. Attention was given to the influence of the aerosol optical thickness in the stratosphere, the single scattering albedo and asymmetry factor, and the sublayer albedo. Calculations were performed of the zonal albedo and the planetary radiation balance, taking into account a stratospheric aerosol layer containing H2SO4 droplets and volcanic ash. The resulting ground temperature disturbance was computed using a Budyko (1969) climate model. Local decreases in the albedo in the summer were observed in high latitudes, implying a heating effect of the aerosol. An accompanying energy loss of 23-27 W/sq m was projected, which translates to surface temperature decreases of either 1.1 and 0.45 C, respectively, for background and volcanic aerosols.

  7. Enhanced air pollution via aerosol-boundary layer feedback in China

    PubMed Central

    Petäjä, T.; Järvi, L.; Kerminen, V.-M.; Ding, A.J.; Sun, J.N.; Nie, W.; Kujansuu, J.; Virkkula, A.; Yang, X.; Fu, C.B.; Zilitinkevich, S.; Kulmala, M.

    2016-01-01

    Severe air pollution episodes have been frequent in China during the recent years. While high emissions are the primary reason for increasing pollutant concentrations, the ultimate cause for the most severe pollution episodes has remained unclear. Here we show that a high concentration of particulate matter (PM) will enhance the stability of an urban boundary layer, which in turn decreases the boundary layer height and consequently cause further increases in PM concentrations. We estimate the strength of this positive feedback mechanism by combining a new theoretical framework with ambient observations. We show that the feedback remains moderate at fine PM concentrations lower than about 200 μg m−3, but that it becomes increasingly effective at higher PM loadings resulting from the combined effect of high surface PM emissions and massive secondary PM production within the boundary layer. Our analysis explains why air pollution episodes are particularly serious and severe in megacities and during the days when synoptic weather conditions stay constant. PMID:26753788

  8. The explanation of barrier height inhomogeneities in Au/n-Si Schottky barrier diodes with organic thin interfacial layer

    NASA Astrophysics Data System (ADS)

    Taşçıoǧlu, Ilke; Aydemir, Umut; Altındal, Şemsettin

    2010-09-01

    The forward bias current-voltage (I-V) characteristics of Au/n-Si Schottky barrier diodes (SBDs) with Zn doped poly(vinyl alcohol) (PVA:Zn) interfacial layer have been investigated in the wide temperature range of 80-400 K. The conventional Richardson plot of the ln(Io/T2) versus q /kT has two linear regions: the first region (200-400 K) and the second region (80-170 K). The values of activation energy (Ea) and Richardson constant (A∗) were obtained from this plot and especially the values of A∗ are much lower than the known theoretical value for n-type Si. Also the value of Ea is almost equal to the half of the band gap energy of Si. Therefore, the Φap versus q /2kT plot was drawn to obtain the evidence of a Gaussian distribution (GD) of barrier heights (BHs) and it shows two linear region similar to ln(Io)/T2 versus q /kT plot. The analysis of I-V data based on thermionic emission of the Au/PVA:Zn/n-Si SBDs has revealed the existence of double GD with mean BH values (Φ¯B0) of 1.06 eV and 0.86 eV with standard deviation (σ ) of 0.110 eV and 0.087 V, respectively. Thus, we modified ln(Io/T2)-(qσ)2/2(kT)2 versus q /kT plot for two temperature regions (200-400 K and 80-170 K) and it gives renewed mean BHs Φ¯B0 values as 1.06 eV and 0.85 eV with Richardson constant (A∗) values 121 A/cm2 K2 and 80.4 A/cm2 K2, respectively. This obtained value of A∗=121 A/cm2 K2 is very close to the known theoretical value of 120 A/cm2 K2 for n-type Si.

  9. The impact of monthly variation of the Pacific-North America (PNA) teleconnection pattern on wintertime surface-layer aerosol concentrations in the United States

    NASA Astrophysics Data System (ADS)

    Feng, Jin; Liao, Hong; Li, Jianping

    2016-04-01

    The Pacific-North America teleconnection (PNA) is the leading general circulation pattern in the troposphere over the region of North Pacific to North America during wintertime. This study examined the impacts of monthly variations of the PNA phase (positive or negative phase) on wintertime surface-layer aerosol concentrations in the United States (US) by analyzing observations during 1999-2013 from the Air Quality System of the Environmental Protection Agency (EPA-AQS) and the model results for 1986-2006 from the global three-dimensional Goddard Earth Observing System (GEOS) chemical transport model (GEOS-Chem). The composite analyses on the EPA-AQS observations over 1999-2013 showed that the average concentrations of PM2.5, sulfate, nitrate, ammonium, organic carbon, and black carbon aerosols over the US were higher in the PNA positive phases (25 % of the winter months examined, and this fraction of months had the highest positive PNA index values) than in the PNA negative phases (25 % of the winter months examined, and this fraction of months had the highest negative PNA index values) by 1.0 µg m-3 (8.7 %), 0.01 µg m-3 (0.5 %), 0.3 µg m-3 (29.1 %), 0.1 µg m-3 (11.9 %), 0.6 µg m-3 (13.5 %), and 0.2 µg m-3 (27.8 %), respectively. The simulated geographical patterns of the differences in concentrations of all aerosol species between the PNA positive and negative phases were similar to observations. Based on the GEOS-Chem simulation, the pattern correlation coefficients were calculated to show the impacts of PNA-induced variations in meteorological fields on aerosol concentrations. The PNA phase was found (i) to influence sulfate concentrations mainly through changes in planetary boundary layer height (PBLH), precipitation (PR), and temperature; (ii) to influence nitrate concentrations mainly through changes in temperature; and (iii) to influence concentrations of ammonium, organic carbon, and black carbon mainly through changes in PR and PBLH. Results from

  10. Volcanic aerosol layer formed in the tropical upper troposphere by the eruption of Mt. Merapi, Java, in November 2010 observed by the spaceborne lidar CALIOP

    NASA Astrophysics Data System (ADS)

    Shibata, Takashi; Kinoshita, Taro

    2016-02-01

    Mt. Merapi in Java, Indonesia, erupted in November 2010. The eruption was proved to be the source of the aerosol layer observed by a ground-based lidar at Biak, Indonesia, in January 2011 using data on the global distribution of aerosols observed by the spaceborne cloud-aerosol lidar with orthogonal polarization (CALIOP). These data were used to describe how the volcanic aerosols produced by the volcanic eruption diffused throughout the tropical tropopause layer (TTL). The equivalent maximum total amount of volcanic SO2 estimated from the spatially integrated total amount of aerosols was 0.09 Tg, which is one-third to half that of gaseous SO2 after the eruption was observed by the ozone monitoring instrument satellite. The obtained cirrus-cloud-appearance frequency data exhibit a seasonal cycle having its maximum in winter and no detectable variations that are synchronized with the increase in TTL volcanic aerosols.

  11. Sudden changes in aerosol and gas concentrations in the central Arctic marine boundary layer: Causes and consequences

    NASA Astrophysics Data System (ADS)

    Bigg, E. Keith; Leck, Caroline; Nilsson, E. Douglas

    2001-12-01

    Measurements of aerosol number size distributions and concentrations of the precursor gases dimethyl sulfide, sulfur dioxide and ammonia were made within the pack ice region of the central Arctic Ocean during July and August 1996 from the icebreaker Oden. Changes in concentration, sometimes exceeding the entire seasonal variation, often occurred within an hour and attempts to find the reasons for them are described. Vertical profiles of aerosol concentration in Aitken and accumulation mode particles obtained on helicopter flights revealed intense concentration gradients in the lowest 1000 m. Those below 100 m were common. Concentrations of accumulation mode particles were usually greater near the surface than at 100 m. Four representative case studies for which vertical aerosol profiles were obtained are presented. Observations of rapid large changes in near-surface concentration of aerosols in different size ranges are compared with the vertical profiles, meteorological information, and acoustic or optical remote sensing to infer processes causing the changes. Comparison of simultaneous variations in aerosols and precursor gas concentrations are used to define the vertical profiles of the gases. It was found that dimethyl sulfide and ammonia concentrations usually must have been strongly depleted near the surface relative to concentrations at about 100 m. Sulfur dioxide profiles appeared to be more complex. Turbulence or vertical air motions initiated by atmospheric wave motions trapped within the stable boundary layer appeared to be directly responsible for many of the sudden concentration changes, through interaction with concentration gradients close to the surface. The presence of low-level jets also had direct or indirect influences on mixing in the lowest few hundred meters. The extent to which aerosols measured near the surface can determine the microphysics of central Arctic marine boundary layer clouds is examined.

  12. The ASTAR 2007 April 14 haze layer: The radiative effect of an aged and internally mixed aerosol in the Arctic

    NASA Astrophysics Data System (ADS)

    Engvall, A.-C.; Ström, J.; Tunved, P.; Schlager, H.; Minikin, A.

    2009-04-01

    INTRODUCTION The ASTAR project (Arctic Study of Tropospheric Aerosol and Radiation) is aimed at investigating the physico-chemical properties of the Arctic tropospheric aerosol by means of aircraft measurements. The goal of the program is to provide an observational dataset for improving not only the assessment of the direct and indirect effects of aerosols on the Arctic radiative balance, but also the aerosol parameterisation in the regional climate model HIRHAM [Rinke, et al., 1999; Treffeisen, et al., 2005]. The ASTAR 2007 campaign was conducted from March 18 - April 18 in 2007, Svalbard. This timing was chosen to make the measurements span during the Arctic spring due to its frequent Arctic hazes. In the present study we focus on an aerosol layer observed north of Svalbard at an altitude of around 3 km during the campaign. Due to recent discussions about the Arctic temperature amplification and the importance of soot in the atmosphere and its radiative effects, the aim of the present study is to evaluate the potential magnitude of the radiative effects such a haze layer might have in the Arctic. METHODS In the present study we have analysed in-situ observations of aerosol number densities of particles larger than 10 nm and 260 nm in diameter (henceforth denoted N10 and N260, respectively), aerosol size distributions, aerosol light scattering and absorption, and concentrations of carbon monoxide (CO) and ozone (O3). The measurements were conducted from the German DLR Falcon 20 research aeroplane. N10 was measured using a condensation particle counter (CPC) model TSI 3010. The aerosol size distribution between 17 and 239 nm was measured with a Differential Mobility Particle Sizer (DMPS) in stepwise mode utilising 13 bins, each of which was measured during 10 s. The aerosol size distribution between 260 and 2200 nm was observed with an optical particle counter (OPC) GRIMM, model 3.709, which sized the particles in 12 bins at 1 Hz. We also used information about

  13. Precise control of Schottky barrier height in SrTiO3/SrRuO3 heterojunctions using ultrathin interface polar layers

    NASA Astrophysics Data System (ADS)

    Sampath Kumar, V.; Niranjan, Manish K.

    2016-06-01

    Control of Schottky barrier height using a polar interface layer at oxide heterointerfaces offers interesting and promising applications in oxide-based electronics. Using ab initio density functional theory, the Schottky barrier heights are determined in SrRuO3 /SrTiO3(0 0 1) heterojunctions with interfacial polar layers such as (LaO)+, (AlO2)-, etc. The Schottky barriers at these heterointerfaces are found to modulate significantly depending on the charge of the interface layer. Large shifts in Schottky barrier height due to polar layer insertions are explained using a micro-capacitor model. Further, the ionic and electronic contributions to the Schottky barrier height at the SrRuO3/SrTiO3 interface are determined and analyzed vis-à-vis basic assumptions of empirical models based on metal-induced gap states (MIGS) and bond polarization theory. In addition, the interface electronic structure and distribution of interface MIGS in SrRuO3/SrTiO3 heterostructures are determined. Furthermore, the electronic structures for SrO- and RuO2-terminated SrRuO3(0 0 1) and SrO- and TiO2-terminated SrTiO3(0 0 1) surfaces are explored and compared to those for SrRuO3/SrTiO3 heterostructures. The modulations in workfunctions of SrO- and RuO2-terminated SrRuO3(0 0 1) surfaces due to polar (LaO)+ and (AlO2)- surface monolayers are also examined and discussed.

  14. Winter monsoon variation of lower tropospheric aerosol layers at a tropical coastal station, Trivandrum (8°33' N, 77°E), India

    NASA Astrophysics Data System (ADS)

    Satyanarayana, M.; Veerabuthiran, S.; Ramakrishna Rao, D.; Presennakumar, B.; Mohankumar, S. V.; Muraleedharan Nair, S.; Sreeja, R.

    Tropospheric aerosols play an important role in cloud physics and radiative transfer process. They show a high degree of variability in their characteristics both in space and time. The features of the background aerosol at any location or region depend to a large extent on the local source regions and various meteorological parameters at the time of measurement. Apart from the natural sources in and around the observatory station, anthropogenic additions of aerosols also affect the radiation budget and chemical composition. Besides this, it is realized in recent years that aerosols generated at one place could be transported over long distances by the wind systems and produce consequent effects at locations much farther away from the source. Such transported aerosols may settle as stratified layers in the atmosphere typically in the altitude of 1 to 4 km. These aerosol layers will have important effect in the local climate and atmospheric environment because of their role in radiative transfer process and cloud physics. Lidar observations had been conducted to study the long-range transport of aerosol and their effect at tropical station, Trivandrum during the northern winter period of 2002-2004. The presence of aerosol layers was observed on many days below 4 km during the above period. The high extinction coefficient is observed in the layer region and typically it is found to be 3.4 x 10-4 m-1. The aerosol optical depth is calculated by integrating the extinction values in the aerosol layer region and it is found to be between 0.25 and 0.35. The plausible reasons for the formation of these layers were explained using the wind circulation pattern and air back trajectories.

  15. Variability of Atmospheric Boundary Layer height over the tropical oceans - A study using atmospheric refractivity profiles from multi campaign in-situ and satellite radio occultation data.

    NASA Astrophysics Data System (ADS)

    Santosh, M.

    2016-07-01

    Atmospheric Boundary Layer (ABL) over the tropical oceans controls and regulates the influx of water vapour into the free atmosphere due to evaporation. The availability of in situ data for determining the ABL characteristics over tropical oceans are limited to different ship based campaigns and hence restricted in spatial and temporal coverage. For ABL studies the Radio Occultation (RO) based satellite data over tropical oceans have good temporal and spatial coverage but limited in temporal and spatial resolution. Atmospheric refractivity profiles are extensively used in many studies to determine the ABL height from both platforms. The present study attempts to use the advantages in both in-situ and satellite (RO) based data to quantify the variability in the ABL height over the tropical oceans. All studies done so far to identify the ABL height from RO derived refractivity profiles rely extensively on the detection of the minimum refractivity gradient (MRG) below ~6 km along with additional threshold criteria. This leads to an over estimation of ABL heights especially in presence of strong subsidence inversion caused by local/ mesoscale/ synoptic scale processes where the MRG lies significantly above the ABL. The present study attempts to quantify this over estimation using atmospheric refractivity profiles derived from thermo-dynamical parameters from radiosonde ascents over the tropical ocean, suggests an improved method of ABL detection and quantifies the variability so deduced. Over 1000 radiosonde ascents from four ship cruises conducted during DYNAMO 2011 field campaign over the tropical Indian Ocean are used for the purpose. ABL heights determined from radiosonde data using traditional methods (using virtual potential temperature and specific humidity) are compared with those identified from simulated atmospheric refractivity profiles from same data (using prevalent methods for RO) to quantify the over estimation. A new method of ABL detection from

  16. Ozone and aerosol distributions measured by airborne lidar during the 1988 Arctic Boundary Layer Experiment

    NASA Technical Reports Server (NTRS)

    Browell, Edward V.; Butler, Carolyn F.; Kooi, Susan A.

    1991-01-01

    Consideration is given to O3 and aerosol distributions measured from an aircraft using a DIAL system in order to study the sources and sinks of gases and aerosols over the tundra regions of Alaska during summer 1988. The tropospheric O3 budget over the Arctic was found to be strongly influenced by stratospheric intrusions. Regions of low aerosol scattering and enhanced O3 mixing ratios were usually correlated with descending air from the upper troposphere or lower stratosphere.

  17. Nanotubes oxidation temperature controls the height of single-walled carbon nanotube forests on gold micropatterned thin layers.

    PubMed

    Lamberti, Francesco; Agnoli, Stefano; Meneghetti, Moreno; Elvassore, Nicola

    2010-07-01

    We developed a simple methodology for a direct control of the height of carboxylated single-walled carbon nanotube (SWNT) forests. We found that the important step is a good control of the oxidation temperature of the nanotubes. SWNTs oxidation at different temperature was followed by Raman and X-ray photoelectron spectroscopies. Atomic force microscopy images showed that micropatterned self-assembled monolayers forests have average height from 20 to 80 nm using SWNTs oxidized in the temperature ranging from 323 to 303 K, respectively.

  18. Global Aerosol Distributions Derived From the CALIPSO Observations

    NASA Astrophysics Data System (ADS)

    Kittaka, C.; Winker, D.; Omar, A.; Liu, Z.; Vaughan, M.; Trepte, C.

    2008-12-01

    Since June 2006, CALIPSO continues to provide routine and systematic measurements of lidar backscatter at two wavelengths, 532 and 1064 nm. As an active sensor, the quality of the measurement is nearly insensitive to surface properties allowing quantitative measurements in regions that are problematic to passive sensors. In particular, aerosol and cloud observations in the polar regions and desert areas are possible with the CALIPSO lidar through the different seasons of a year. The CALIPSO level 2 products, which include aerosol and cloud vertical profiles along tracks, reveal, for the first time, the multi-layer structure of aerosols and clouds on a global scale. This allows not only a depiction of aerosols in relation to clouds, but also the investigation of the interaction between aerosols and clouds. In this study, we present global distributions of aerosol in terms of season, layer height, aerosol species, and in relation to clouds using two years of CALIPSO observations. The CALIPSO aerosol extinction data sets under clear sky are evaluated against the AERONET aerosol optical depth (AOD) and the MODIS AOD collection 5 data sets. The agreement and discrepancies from these comparisons are characterized regionally and investigated using other CALIPSO observable and retrieved parameters. Furthermore, aerosols above clouds and in the vicinity of clouds are examined on a global scale. The implications for aerosol radiative forcing are discussed, highlighting the new and interesting aerosol features obtained from CALIPSO observations.

  19. Massive-scale aircraft observations of giant sea-salt aerosol particle size distributions in atmospheric marine boundary layers

    NASA Astrophysics Data System (ADS)

    Jensen, J. B.

    2015-12-01

    iant sea-salt aerosol particles (dry radius, rd > 0.5 μm) occur nearly everywhere in the marine boundary layer and frequently above. This study presents observations of atmospheric sea-salt size distributions in the range 0.7 < rd < 14 μm based on external impaction of sea-spray aerosol particles onto microscope polycarbonate microscope slides. The slides have very large sample volumes, typically about 250 L over a 10-second sampling period. This provides unprecedented sampling of giant sea-salt particles for flights in marine boundary layer air. The slides were subsequently analyzed in a humidified chamber using dual optical digital microscopy. At a relative humidity of 90% the sea-salt aerosol particles form spherical cap drops. Based on measurement the volume of the spherical cap drop and assuming NaCl composition, the Kohler equation is used to derive the dry salt mass of tens of thousands of individual aerosol particles on each slide. Size distributions are given with a 0.2 μm resolution. The slides were exposed from the NSF/NCAR C-130 research aircraft during the 2008 VOCALS project off the coast of northern Chile and the 2011 ICE-T in the Caribbean. In each deployment, size distributions using hundreds of slides are used to relate fitted log-normal size distributions parameters to wind speed, altitude and other atmospheric conditions. The size distributions provide a unique observational set for initializing cloud models with coarse-mode aerosol particle observations for marine atmospheres.

  20. Chemical relations between atmospheric aerosols, deposition and stone decay layers on historic buildings at the mediterranean coast

    NASA Astrophysics Data System (ADS)

    Torfs, K.; Van Grieken, R.

    To evaluate the effects of the environment on weathering of historical buildings in the Mediterranean Basin, an elaborate study has been carried out at four monuments, with specific interest directed on the action of air pollution and marine salts. The composition of the atmosphere around the monuments has been investigated by monitoring the aerosols and the total deposition. These results are combined with the stone decay phenomena to interpret the deterioration at the respective monuments. In Eleusis, Greece, a highly industrialized area, high concentrations of heavy metals and sulphate are found in the aerosols and deposition and in the decay layers of the stone, while the marine influence is obscured, in spite of its location close to the sea. In Malta and in Cadiz (Spain), the influence of the sea dominates in the stone weathering process. In Bari (Italy), next to the effects of marine aerosols on the stone decay inside and outside the building, high concentrations of sulphate are observed on the outside stones. The aerosols and depositions reflect a relatively small influence of anthropogenic derived elements; this points out the action of gaseous SO 2 on the stones.

  1. Airborne LIDAR Measurements of Aerosol and Ozone Above the Alberta Oil Sands Region

    NASA Astrophysics Data System (ADS)

    Aggarwal, M.; Whiteway, J. A.; Seabrook, J.; Gray, L. H.

    2014-12-01

    Lidar measurements of ozone and aerosol were conducted from a Twin Otter aircraft above the oil sands region of northern Alberta. The field campaign was carried out with a total of five flights out of Fort McMurray, Alberta during the period between August 22 and August 26, 2013. Significant amounts of aerosol were observed within the boundary layer, up to a height of 1.6 km, but the ozone concentration remained at or below background levels. On August 24th the lidar observed a separated layer of aerosol above the boundary layer, at a height of 1.8 km, in which the ozone mixing ratio increased to 70 ppbv. Backward trajectory calculations revealed that the air containing this separated aerosol layer had passed over an area of forest fires. Directly below the layer of forest fire smoke, in the pollution from the oil sands industry, the measured ozone mixing ratio was lower than the background levels (≤35 ppbv).

  2. Implementation and evaluation of the Heffter method to calculate the height of the planetary boundary layer above the ARM Southern Great Plains site

    SciTech Connect

    Pesenson, Igor

    2003-11-30

    This paper explores the Heffter Method--an algorithm for finding the height of the Planetary Boundary Layer (PBL). The algorithm is applied to the Balloon Borne Sounding System (BBSS) data collected over the Southern Great Plains (SGP) Site of the Atmospheric Radiation Measurement (ARM) Program. After discussing the successes and shortcomings of the algorithm, the resulting PBL height estimates for dates in May of 2002 are related to CO{sub 2} concentration and wind data. The CO{sub 2} data used is from the Precision Gas System (PGS) while the wind data is a combination of data from the Portable CO{sub 2} Flux System on the SGP site and BBSS.

  3. The Impacts of Contact Etch Stop Layer Thickness and Gate Height on Channel Stress in Strained N-Metal Oxide Semiconductor Field Effect Transistors.

    PubMed

    Lin, K C; Twu, M J; Deng, R H; Liu, C H

    2015-04-01

    The stress induced by strain in the channel of metal oxide semiconductor field effect transistors (MOSFET) is an effective method to boost the device performance. The geometric dimensions of spacer, gate height, and the contact etch stop layer (CESL) are important factors among the feasible booster. This study utilized the mismatch of the thermal expansion coefficients of stressors to simulate the process-induced stress in the N-MOSFET. Different temperatures are applied to different region of the device to generate the required strain. The analysis was performed by well-developed finite element package. The composite spacers with variant width of inserted silicon nitride (SiO2/SiN/SiO2, ONO) were proposed and their impacts on channel stress were compared. Two aspects of the impacts of those factors on the channel stress in the longitudinal direction for N-MOSFET with variant channel length were investigated. Firstly, the channel stresses of device without CESL for different gate heights were studied. Secondly, with stress applied to CESL and ONO spacers, the induced stresses in the channel were analyzed for long/short gate length. Two conclusions were drawn from the results of simulation. The N-MOSFET device without CESL shows that the stressed spacer alone generates compressive stress and the magnitude increases along with higher gate height. The channel stress becomes tensile for device with CESL and increases when the thickness of CESL and the height of gate increase, especially for device with shorter gate length. The gate height plays more significant role in inducing channel stress compared with the thickness of CESL. The channel stress can be used to quantify the mobility of electron/hole for strained MOSFET device. Therefore, with the guideline disclosed in this study, better device performance can be expected for N-MOSFET. PMID:26353480

  4. The seasonal and solar cycle variations of electron density gradient scale length, vertical drift and layer height during magnetically quiet days: Implications for Spread F over Trivandrum, India

    NASA Astrophysics Data System (ADS)

    Manju, G.; Devasia, C. V.; Ravindran, S.

    2009-12-01

    A study has been carried out on the behaviour of electron density gradient scale length, L, vertical drift and layer height, around post sunset hours, during the magnetically quiet days of summer, winter and equinox seasons of solar maximum (2002) and minimum years (1995), using ionosonde data of Trivandrum (8.5°N, 76.5°E, dip = 0.5°N) in the Indian longitude sector. The results indicate a clear seasonal and solar cycle variation in all the three parameters. Further, the seasonal variation of equatorial Spread F (ESF) during the above period is examined in terms of the relative roles of L, the vertical drift and layer height (of the F layer) in the triggering of the collisional Rayleigh-Taylor instability. The results, show for the first time, that L also plays an important role, in controlling the quiet time seasonal and solar cycle variability of ESF; whereas in earlier studies this parameter had been taken to be constant. The detailed results are presented and discussed.

  5. Study on aerosol optical properties and radiative effect in cloudy weather in the Guangzhou region.

    PubMed

    Deng, Tao; Deng, XueJiao; Li, Fei; Wang, ShiQiang; Wang, Gang

    2016-10-15

    Currently, Guangzhou region was facing the problem of severe air pollution. Large amount of aerosols in the polluted air dramatically attenuated solar radiation. This study investigated the vertical optical properties of aerosols and inverted the height of boundary layer in the Guangzhou region using the lidar. Simultaneously, evaluated the impact of different types of clouds on aerosol radiation effects using the SBDART. The results showed that the height of the boundary layer and the surface visibility changed consistently, the average height of the boundary layer on the hazy days was only 61% of that on clear days. At the height of 2km or lower, the aerosol extinction coefficient profile distribution decreased linearly along with height on clear days, but the haze days saw an exponential decrease. When there was haze, the changing of heating rate of atmosphere caused by the aerosol decreased from 3.72K/d to 0.9K/d below the height of 2km, and the attenuation of net radiation flux at the ground surface was 97.7W/m(2), and the attenuation amplitude was 11.4%; when there were high clouds, the attenuation was 125.2W/m(2) and the attenuation amplitude was 14.6%; where there were medium cloud, the attenuation was 286.4W/m(2) and the attenuation amplitude was 33.4%. Aerosol affected mainly shortwave radiation, and affected long wave radiation very slightly. PMID:27295588

  6. Study on aerosol optical properties and radiative effect in cloudy weather in the Guangzhou region.

    PubMed

    Deng, Tao; Deng, XueJiao; Li, Fei; Wang, ShiQiang; Wang, Gang

    2016-10-15

    Currently, Guangzhou region was facing the problem of severe air pollution. Large amount of aerosols in the polluted air dramatically attenuated solar radiation. This study investigated the vertical optical properties of aerosols and inverted the height of boundary layer in the Guangzhou region using the lidar. Simultaneously, evaluated the impact of different types of clouds on aerosol radiation effects using the SBDART. The results showed that the height of the boundary layer and the surface visibility changed consistently, the average height of the boundary layer on the hazy days was only 61% of that on clear days. At the height of 2km or lower, the aerosol extinction coefficient profile distribution decreased linearly along with height on clear days, but the haze days saw an exponential decrease. When there was haze, the changing of heating rate of atmosphere caused by the aerosol decreased from 3.72K/d to 0.9K/d below the height of 2km, and the attenuation of net radiation flux at the ground surface was 97.7W/m(2), and the attenuation amplitude was 11.4%; when there were high clouds, the attenuation was 125.2W/m(2) and the attenuation amplitude was 14.6%; where there were medium cloud, the attenuation was 286.4W/m(2) and the attenuation amplitude was 33.4%. Aerosol affected mainly shortwave radiation, and affected long wave radiation very slightly.

  7. Measuring the characteristics of stratospheric aerosol layer and total ozone concentration at Siberian Lidar Station in Tomsk

    NASA Astrophysics Data System (ADS)

    Nevzorov, Aleksey; Bazhenov, Oleg; Burlakov, Vladimir; Dolgii, Sergey

    2015-11-01

    We consider the results of long-term remote optical monitoring, obtained at the Siberian Lidar Station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences in Tomsk (56.5 °N, 85.0 °E). The scattering characteristics of stratospheric aerosol layer, obtained according to data of lidar measurements since 1986, are presented. We analyze the trends of changes in the total ozone (TO) content over Tomsk for the period 1996-2013 according to data of spectrophotometric measurements with employment of TOMS satellite data for the period 1979- 1994. We determined the periods of elevated content of stratospheric aerosol over Tomsk after a series of explosive eruptions of volcanoes of Pacific Ring of Fire and Iceland in 2006-2011. Since the second half of 1990s, researchers record an increasing TO trend, equaling 0.65 DU/yr for the period 1996-2013.

  8. Certain Results of Measurements of Characteristics of Stratospheric Aerosol Layer and Total Ozone Content at Siberian Lidar Station in Tomsk

    NASA Astrophysics Data System (ADS)

    Nevzorov, Aleksey; Bazhenov, Oleg; Burlakov, Vladimir; Dolgii, Sergey

    2016-06-01

    We consider the results of long-term remote optical monitoring, obtained at the Siberian Lidar Station of Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences in Tomsk (56.5°N, 85.0°E). The scattering characteristics of stratospheric aerosol layer, obtained according to data of lidar measurements since 1986, are presented. We analyze the trends of changes in the total ozone (TO) content over Tomsk for the period 1996-2013 according to data of spectrophotometric measurements with employment of Total Ozone Mapping Spectrometer (TOMS) data for the period 1979-1994. We determined the periods of elevated content of stratospheric aerosol over Tomsk aftera series of explosive eruptions of volcanoes of Pacific Ring of Fire and Iceland in 2006-2011. Since the second half of 1990s, we record an increasing TO trend, equaling 0.65 DU/yr for the period 1996-2013.

  9. Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison

    DOE PAGES

    Wyant, M. C.; Bretherton, Christopher S.; Wood, Robert; Carmichael, Gregory; Clarke, A. D.; Fast, Jerome D.; George, R.; Gustafson, William I.; Hannay, Cecile; Lauer, Axel; et al

    2015-01-09

    A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar tomore » observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol–cloud interactions in the MBL, though quantitative estimation of aerosol–cloud interactions and aerosol indirect effects of MBL clouds

  10. Global and regional modeling of clouds and aerosols in the marine boundary layer during VOCALS: the VOCA intercomparison

    SciTech Connect

    Wyant, M. C.; Bretherton, Christopher S.; Wood, Robert; Carmichael, Gregory; Clarke, A. D.; Fast, Jerome D.; George, R.; Gustafson, William I.; Hannay, Cecile; Lauer, Axel; Lin, Yanluan; Morcrette, J. -J.; Mulcahay, Jane; Saide, Pablo; Spak, S. N.; Yang, Qing

    2015-01-09

    A diverse collection of models are used to simulate the marine boundary layer in the southeast Pacific region during the period of the October–November 2008 VOCALS REx (VAMOS Ocean Cloud Atmosphere Land Study Regional Experiment) field campaign. Regional models simulate the period continuously in boundary-forced free-running mode, while global forecast models and GCMs (general circulation models) are run in forecast mode. The models are compared to extensive observations along a line at 20° S extending westward from the South American coast. Most of the models simulate cloud and aerosol characteristics and gradients across the region that are recognizably similar to observations, despite the complex interaction of processes involved in the problem, many of which are parameterized or poorly resolved. Some models simulate the regional low cloud cover well, though many models underestimate MBL (marine boundary layer) depth near the coast. Most models qualitatively simulate the observed offshore gradients of SO2, sulfate aerosol, CCN (cloud condensation nuclei) concentration in the MBL as well as differences in concentration between the MBL and the free troposphere. Most models also qualitatively capture the decrease in cloud droplet number away from the coast. However, there are large quantitative intermodel differences in both means and gradients of these quantities. Many models are able to represent episodic offshore increases in cloud droplet number and aerosol concentrations associated with periods of offshore flow. Most models underestimate CCN (at 0.1% supersaturation) in the MBL and free troposphere. The GCMs also have difficulty simulating coastal gradients in CCN and cloud droplet number concentration near the coast. The overall performance of the models demonstrates their potential utility in simulating aerosol–cloud interactions in the MBL, though quantitative estimation of aerosol–cloud interactions and aerosol indirect effects of MBL

  11. Interpretation of FRESCO cloud retrievals in case of absorbing aerosol events

    NASA Astrophysics Data System (ADS)

    Wang, P.; Tuinder, O. N. E.; Tilstra, L. G.; Stammes, P.

    2011-12-01

    Cloud and aerosol information is needed in trace gas retrievals from satellite measurements. The Fast REtrieval Scheme for Clouds from the Oxygen A band (FRESCO) cloud algorithm employs reflectance spectra of the O2 A band around 760 nm to derive cloud pressure and effective cloud fraction. In general, clouds contribute more to the O2 A band reflectance than aerosols. Therefore, the FRESCO algorithm does not correct for aerosol effects in the retrievals and attributes the retrieved cloud information entirely to the presence of clouds, and not to aerosols. For events with high aerosol loading, aerosols may have a dominant effect, especially for almost cloud-free scenes. We have analysed FRESCO cloud data and Absorbing Aerosol Index (AAI) data from the Global Ozone Monitoring Experiment (GOME-2) instrument on the Metop-A satellite for events with typical absorbing aerosol types, such as volcanic ash, desert dust and smoke. We find that the FRESCO effective cloud fractions are correlated with the AAI data for these absorbing aerosol events and that the FRESCO cloud pressures contain information on aerosol layer pressure. For cloud-free scenes, the derived FRESCO cloud pressures are close to those of the aerosol layer for optically thick aerosols. For cloudy scenes, if the strongly absorbing aerosols are located above the clouds, then the retrieved FRESCO cloud pressures may represent the height of the aerosol layer rather than the height of the clouds. Combining FRESCO cloud data and AAI, an estimate for the aerosol layer pressure can be given, which can be beneficial for aviation safety and operations in case of e.g. volcanic ash plumes.

  12. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, M.; Muñoz-Esparza, D.; Chouza, F.; Reitebuch, O.; Knoth, O.; Haarig, M.; Ansmann, A.

    2016-01-01

    Large eddy simulations (LESs) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude potential temperature perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind and Raman lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ≈ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the downwind vertical wind structure. Additionally, the model results accurately reproduce the

  13. Signature of 3-4 day planetary waves in the equatorial ionospheric F layer height and medium frequency radar winds over Tirunelveli (8.7oN)

    NASA Astrophysics Data System (ADS)

    Sundararaman, Sathishkumar

    Signature of 3-4 day planetary waves in the equatorial ionospheric F layer height and medium frequency radar winds over Tirunelveli (8.7oN) S. Sathishkumar1, R. Dhanya1, K. Emperumal1, D. Tiwari2, S. Gurubaran1 and A. Bhattacharyya2 1. Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Tirunelveli, India 2. Indian Institute of Geomagnetism, Navi Mumbai, India Email: sathishmaths@gmail.com Abstract The equatorial atmosphere-ionosphere system has been studied theoretically and observationally in the past. In the equatorial atmosphere, oscillations with periods of 3-4 days are often observed in the medium frequency (MF) radar over Tirunelveli (8.7oN, 77.8oE, 1.34oN geomag. lat.). Earlier observations show the clear evidence that these waves can propagate from the stratosphere to ionosphere. A digital ionosonde has been providing useful information on several ionospheric parameters from the same site. Simultaneous observations of mesospheric winds using medium frequency radar and F-layer height (h'F) from ionosonde reveal that the 3-4 day wave was evident in both the component during the 01 June 2007 and 31 July 2007. The 3-4 day wave could have an important role in the day to day variability of the equatorial ionosphere evening uplift. Results from an extensive analysis that is being carried out in the direction of 3-4 day wave present in the ionosphere will be presented.

  14. Modifications of the quasi-biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer

    NASA Astrophysics Data System (ADS)

    Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

    2014-03-01

    This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System version 5 Chemistry Climate Model. We performed four 30 year simulations with a continuous injection of sulfur dioxide on the equator at 0° longitude. The four simulations differ by the amount of sulfur dioxide injected (5 Tg/yr and 2.5 Tg/yr) and the altitude of the injection (16 km-25 km and 22 km-25 km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. This is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere and higher residual vertical velocity. In the case of maximum perturbation, i.e., highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase.

  15. Modifications of the Quasi-biennial Oscillation by a Geoengineering Perturbation of the Stratospheric Aerosol Layer

    NASA Technical Reports Server (NTRS)

    Aquila, V.; Garfinkel, C. I.; Newman, P. A.; Oman, L. D.; Waugh, D. W.

    2014-01-01

    This paper examines the impact of geoengineering via stratospheric sulfate aerosol on the quasi-biennial oscillation (QBO) using the NASA Goddard Earth Observing System (GEOS-5) Chemistry Climate Model. We performed four 30-year simulations with a continuous injection of sulfur dioxide on the equator at 0 degree longitude. The four simulations differ by the amount of sulfur dioxide injected (5Tg per year and 2.5 Tg per year) and the altitude of the injection (16km-25km and 22km-25km). We find that such an injection dramatically alters the quasi-biennial oscillation, prolonging the phase of easterly shear with respect to the control simulation. In the case of maximum perturbation, i.e. highest stratospheric aerosol burden, the lower tropical stratosphere is locked into a permanent westerly QBO phase. This locked QBO westerly phase is caused by the increased aerosol heating and associated warming in the tropical lower stratosphere.

  16. Isotopic constraints on the role of hypohalous acids in sulfate aerosol formation in the remote marine boundary layer

    NASA Astrophysics Data System (ADS)

    Chen, Qianjie; Geng, Lei; Schmidt, Johan A.; Xie, Zhouqing; Kang, Hui; Dachs, Jordi; Cole-Dai, Jihong; Schauer, Andrew J.; Camp, Madeline G.; Alexander, Becky

    2016-09-01

    Sulfate is an important component of global atmospheric aerosol, and has partially compensated for greenhouse gas-induced warming during the industrial period. The magnitude of direct and indirect radiative forcing of aerosols since preindustrial times is a large uncertainty in climate models, which has been attributed largely to uncertainties in the preindustrial environment. Here, we report observations of the oxygen isotopic composition (Δ17O) of sulfate aerosol collected in the remote marine boundary layer (MBL) in spring and summer in order to evaluate sulfate production mechanisms in pristine-like environments. Model-aided analysis of the observations suggests that 33-50 % of sulfate in the MBL is formed via oxidation by hypohalous acids (HOX = HOBr + HOCl), a production mechanism typically excluded in large-scale models due to uncertainties in the reaction rates, which are due mainly to uncertainties in reactive halogen concentrations. Based on the estimated fraction of sulfate formed via HOX oxidation, we further estimate that daily-averaged HOX mixing ratios on the order of 0.01-0.1 parts per trillion (ppt = pmol/mol) in the remote MBL during spring and summer are sufficient to explain the observations.

  17. Aircraft measurements of ozone, NOx, CO, and aerosol concentrations in biomass burning smoke over Indonesia and Australia in October 1997: Depleted ozone layer at low altitude over Indonesia

    NASA Astrophysics Data System (ADS)

    Tsutsumi, Yukitomo; Sawa, Yousuke; Makino, Yukio; Jensen, Jørgen B.; Gras, John L.; Ryan, Brian F.; Diharto, Sri; Harjanto, Hery

    The 1997 El Niño unfolded as one of the most sever El Niño Southern Oscillation (ENSO) events in this century and it coincided with massive biomass burning in the equatorial western Pacific region. To assess the influence on the atmosphere, aircraft observations of trace gases and aerosol were conducted over Kalimantan in Indonesia and Australia. Over Kalimantan in Indonesia, high concentrations of O3, NOx, CO, and aerosols were observed during the flight. Although the aerosol and NOx decreased with altitude, the O3 had the maximum concentration (80.5 ppbv) in the middle layer of the smoke haze and recorded very low concentrations (˜20 ppbv) in the lower smoke layer. This feature was not observed in the Australian smoke. We proposed several hypotheses for the low O3 concentration at low levels over Kalimantan. The most likely are lack of solar radiation and losses at the surface of aerosol particles.

  18. Investigations of boundary layer structure, cloud characteristics and vertical mixing of aerosols at Barbados with large eddy simulations

    NASA Astrophysics Data System (ADS)

    Jähn, M.; Muñoz-Esparza, D.; Chouza, F.; Reitebuch, O.

    2015-08-01

    Large eddy simulations (LES) are performed for the area of the Caribbean island Barbados to investigate island effects on boundary layer modification, cloud generation and vertical mixing of aerosols. Due to the presence of a topographically structured island surface in the domain center, the model setup has to be designed with open lateral boundaries. In order to generate inflow turbulence consistent with the upstream marine boundary layer forcing, we use the cell perturbation method based on finite amplitude perturbations. In this work, this method is for the first time tested and validated for moist boundary layer simulations with open lateral boundary conditions. Observational data obtained from the SALTRACE field campaign is used for both model initialization and a comparison with Doppler wind lidar data. Several numerical sensitivity tests are carried out to demonstrate the problems related to "gray zone modeling" when using coarser spatial grid spacings beyond the inertial subrange of three-dimensional turbulence or when the turbulent marine boundary layer flow is replaced by laminar winds. Especially cloud properties in the downwind area west of Barbados are markedly affected in these kinds of simulations. Results of an additional simulation with a strong trade-wind inversion reveal its effect on cloud layer depth and location. Saharan dust layers that reach Barbados via long-range transport over the North Atlantic are included as passive tracers in the model. Effects of layer thinning, subsidence and turbulent downward transport near the layer bottom at z ~ 1800 m become apparent. The exact position of these layers and strength of downward mixing is found to be mainly controlled atmospheric stability (especially inversion strength) and wind shear. Comparisons of LES model output with wind lidar data show similarities in the formation of the daytime convective plume and the mean vertical wind structure.

  19. Aerosol-cloud-drizzle interactions in warm boundary layer clouds using ground-based measurements from Atlantic and continental European sites

    NASA Astrophysics Data System (ADS)

    Mann, Julian; Chiu, Christine; Hogan, Robin; O'Connor, Ewan

    2013-04-01

    Aerosol impacts the climate directly through scattering and absorbing radiation, and indirectly through altering properties of clouds and precipitation. With increasing ambient aerosol concentration, it is agreed that the redistribution of cloud water to more numerous, but smaller cloud droplets suppresses precipitation. However, the magnitude of precipitation suppression is uncertain, and the response of total cloud water to aerosol concentration remains poorly observed and understood. To better understand how aerosols regulate macro- and microphysical properties of boundary-layer clouds, and to establish statistical relationships of aerosol-cloud-precipitation interactions, we analyze high-temporal resolution observations from the Atmospheric Radiation Measurement (ARM) Mobile Facility deployments in Germany in 2007 and in the Azores during 2009-2010. Through synergy between ground-based aerosol observing systems, active and passive remote sensing instruments, we will show how the drizzle rate at cloud base varies with aerosol concentration. We will also demonstrate how the probability of precipitation and the precipitation susceptibility respond to ambient aerosol concentration, and whether these responses agree with results from state-of-the-art satellite observations and climate models.

  20. Experimental evaluation of atmospheric aerosol turbidity in different Atlantic regions

    SciTech Connect

    Plakhina, I.N.; Pyrogov, S.M.

    1994-12-31

    The statistical estimation of the experimental values of atmospheric turbidity are considered over the different Atlantic regions: from clean atmospheric conditions to very turbid conditions influenced by air masses from Africa containing continental Sahara aerosol. The factors influencing the variability of atmospheric turbidity are also analyzed. The contribution of aerosol to atmospheric attenuation of the direct solar radiation is estimated. It is shown that aerosol is the main factor determining the values of the optical thickness and its variability. The single scattering albedo is evaluated. The influence of the Sahara dust on the total solar radiation over the ocean surface is estimated. Based on the found relationship between aerosol optical thickness, total atmosphere, and aerosol turbidity in the surface layer, the height of the homogeneous atmosphere has been estimated. In addition, the aerosol generation by ocean surface in storm conditions has been considered.

  1. Complex Aerosol Experiment in Western Siberia (April - October 2013)

    NASA Astrophysics Data System (ADS)

    Matvienko, G. G.; Belan, B. D.; Panchenko, M. V.; Romanovskii, O. A.; Sakerin, S. M.; Kabanov, D. M.; Turchinovich, S. A.; Turchinovich, Yu. S.; Eremina, T. A.; Kozlov, V. S.; Terpugova, S. A.; Pol'kin, V. V.; Yausheva, E. P.; Chernov, D. G.; Zuravleva, T. B.; Bedareva, T. V.; Odintsov, S. L.; Burlakov, V. D.; Arshinov, M. Yu.; Ivlev, G. A.; Savkin, D. E.; Fofonov, A. V.; Gladkikh, V. A.; Kamardin, A. P.; Balin, Yu. S.; Kokhanenko, G. P.; Penner, I. E.; Samoilova, S. V.; Antokhin, P. N.; Arshinova, V. G.; Davydov, D. K.; Kozlov, A. V.; Pestunov, D. A.; Rasskazchikova, T. M.; Simonenkov, D. V.; Sklyadneva, T. K.; Tolmachev, G. N.; Belan, S. B.; Shmargunov, V. P.

    2016-06-01

    The primary project objective was to accomplish the Complex Aerosol Experiment, during which the aerosol properties should be measured in the near-ground layer and free atmosphere. Three measurement cycles were performed during the project implementation: in spring period (April), when the maximum of aerosol generation is observed; in summer (July), when atmospheric boundary layer height and mixing layer height are maximal; and in late summer - early autumn (October), when the secondary particle nucleation period is recorded. Numerical calculations were compared with measurements of fluxes of downward solar radiation. It was shown that the relative differences between model and experimental values of fluxes of direct and total radiation, on the average, do not exceed 1% and 3% respectively.

  2. Modelling non-equilibrium secondary organic aerosol formation and evaporation with the aerosol dynamics, gas- and particle-phase chemistry kinetic multi-layer model ADCHAM

    NASA Astrophysics Data System (ADS)

    Roldin, P.; Eriksson, A. C.; Nordin, E. Z.; Hermansson, E.; Mogensen, D.; Rusanen, A.; Boy, M.; Swietlicki, E.; Svenningsson, B.; Zelenyuk, A.; Pagels, J.

    2014-01-01

    We have developed the novel Aerosol Dynamics, gas- and particle-phase chemistry model for laboratory CHAMber studies (ADCHAM). The model combines the detailed gas phase Master Chemical Mechanism version 3.2, an aerosol dynamics and particle phase chemistry module (which considers acid catalysed oligomerization, heterogeneous oxidation reactions in the particle phase and non-ideal interactions between organic compounds, water and inorganic ions) and a kinetic multilayer module for diffusion limited transport of compounds between the gas phase, particle surface and particle bulk phase. In this article we describe and use ADCHAM to study: (1) the mass transfer limited uptake of ammonia (NH3) and formation of organic salts between ammonium (NH4+) and carboxylic acids (RCOOH), (2) the slow and almost particle size independent evaporation of α-pinene secondary organic aerosol (SOA) particles, and (3) the influence of chamber wall effects on the observed SOA formation in smog chambers. ADCHAM is able to capture the observed α-pinene SOA mass increase in the presence of NH3(g). Organic salts of ammonium and carboxylic acids predominantly form during the early stage of SOA formation. These salts contribute substantially to the initial growth of the homogeneously nucleated particles. The model simulations of evaporating α-pinene SOA particles support the recent experimental findings that these particles have a semi-solid tar like amorphous phase state. ADCHAM is able to reproduce the main features of the observed slow evaporation rates if low-volatility and viscous oligomerized SOA material accumulates in the particle surface layer upon evaporation. The evaporation rate is mainly governed by the reversible decomposition of oligomers back to monomers. Finally, we demonstrate that the mass transfer limited uptake of condensable organic compounds onto wall deposited particles or directly onto the Teflon chamber walls of smog chambers can have profound influence on the

  3. Fire emission heights in the climate system - Part 2: Impact on transport, black carbon concentrations and radiation

    NASA Astrophysics Data System (ADS)

    Veira, A.; Kloster, S.; Schutgens, N. A. J.; Kaiser, J. W.

    2015-07-01

    into the free troposphere (FT) and 75 % into the planetary boundary layer (PBL), leads to a TOA RF of -0.24±0.06 W m-2. Overall, we conclude that simple plume height parametrizations provide sufficient representations of emission heights for global climate modeling. Significant improvements in aerosol wildfire modeling likely depend on better emission inventories and aerosol process modeling rather than on improved emission height parametrizations.

  4. Growth of ultrahigh-Sn-content Ge1- x Sn x epitaxial layer and its impact on controlling Schottky barrier height of metal/Ge contact

    NASA Astrophysics Data System (ADS)

    Suzuki, Akihiro; Nakatsuka, Osamu; Shibayama, Shigehisa; Sakashita, Mitsuo; Takeuchi, Wakana; Kurosawa, Masashi; Zaima, Shigeaki

    2016-04-01

    We examined the epitaxial growth of an ultrahigh-Sn-content Ge1- x Sn x layer on a Ge substrate and investigated the impact of a Ge1- x Sn x interlayer on the Schottky barrier height (SBH) of the metal/Ge contact. In this study, we considered guidelines of the strain energy and growth temperature to realize a high-Sn-content Ge1- x Sn x layer while keeping the epitaxial growth and suppressing the Sn precipitation. By reducing the film thickness and keeping a low growth temperature, we formed an atomically flat and uniform Ge1- x Sn x epitaxial layer with a Sn content up to 46% on a Ge(001) substrate. We also performed the current density-voltage measurement for Al/Ge1- x Sn x /n-Ge Schottky diodes to estimate the SBH. We found that the SBH of Al/Ge1- x Sn x /n-Ge contact decreases with increasing Sn content in the Ge1- x Sn x interlayer. The shift of the pinning position towards the conduction band edge of Ge is one of the reasons for the SBH reduction of Al/Ge1- x Sn x /n-Ge contact because the valence band edge of Ge1- x Sn x would rise as the Sn content increases.

  5. Optical and microphysical characterization of aerosol layers over South Africa by means of multi-wavelength depolarization and Raman lidar measurements

    NASA Astrophysics Data System (ADS)

    Giannakaki, Elina; van Zyl, Pieter G.; Müller, Detlef; Balis, Dimitris; Komppula, Mika

    2016-07-01

    Optical and microphysical properties of different aerosol types over South Africa measured with a multi-wavelength polarization Raman lidar are presented. This study could assist in bridging existing gaps relating to aerosol properties over South Africa, since limited long-term data of this type are available for this region. The observations were performed under the framework of the EUCAARI campaign in Elandsfontein. The multi-wavelength PollyXT Raman lidar system was used to determine vertical profiles of the aerosol optical properties, i.e. extinction and backscatter coefficients, Ångström exponents, lidar ratio and depolarization ratio. The mean microphysical aerosol properties, i.e. effective radius and single-scattering albedo, were retrieved with an advanced inversion algorithm. Clear differences were observed for the intensive optical properties of atmospheric layers of biomass burning and urban/industrial aerosols. Our results reveal a wide range of optical and microphysical parameters for biomass burning aerosols. This indicates probable mixing of biomass burning aerosols with desert dust particles, as well as the possible continuous influence of urban/industrial aerosol load in the region. The lidar ratio at 355 nm, the lidar ratio at 532 nm, the linear particle depolarization ratio at 355 nm and the extinction-related Ångström exponent from 355 to 532 nm were 52 ± 7 sr, 41 ± 13 sr, 0.9 ± 0.4 % and 2.3 ± 0.5, respectively, for urban/industrial aerosols, while these values were 92 ± 10 sr, 75 ± 14 sr, 3.2 ± 1.3 % and 1.7 ± 0.3, respectively, for biomass burning aerosol layers. Biomass burning particles are larger and slightly less absorbing compared to urban/industrial aerosols. The particle effective radius were found to be 0.10 ± 0.03, 0.17 ± 0.04 and 0.13 ± 0.03 µm for urban/industrial, biomass burning, and mixed aerosols, respectively, while the single-scattering albedo at 532 nm was 0.87 ± 0.06, 0.90 ± 0.06, and 0.88 ± 0.07 (at 532

  6. Major Influence of Tropical Volcanic Eruptions on the Stratospheric Aerosol Layer During the Last Decade

    NASA Technical Reports Server (NTRS)

    Vernier, Jean-Paul; Thomason, Larry W.; Pommereau, J.-P.; Bourassa, Adam; Pelon, Jacques; Garnier, Anne; Hauchecorne, A.; Blanot, L.; Trepte, Charles R.; Degenstein, Doug; Vargas, F.

    2011-01-01

    The variability of stratospheric aerosol loading between 1985 and 2010 is explored with measurements from SAGE II, CALIPSO, GOMOS/ENVISAT, and OSIRIS/Odin space-based instruments. We find that, following the 1991 eruption of Mount Pinatubo, stratospheric aerosol levels increased by as much as two orders of magnitude and only reached background levels between 1998 and 2002. From 2002 onwards, a systematic increase has been reported by a number of investigators. Recently, the trend, based on ground-based lidar measurements, has been tentatively attributed to an increase of SO2 entering the stratosphere associated with coal burning in Southeast Asia. However, we demonstrate with these satellite measurements that the observed trend is mainly driven by a series of moderate but increasingly intense volcanic eruptions primarily at tropical latitudes. These events injected sulfur directly to altitudes between 18 and 20 km. The resulting aerosol particles are slowly lofted into the middle stratosphere by the Brewer-Dobson circulation and are eventually transported to higher latitudes.

  7. Accuracy of near-surface aerosol extinction determined from columnar aerosol optical depth measurements in Reno, NV, USA

    NASA Astrophysics Data System (ADS)

    Loría-Salazar, S. Marcela; Arnott, W. Patrick; Moosmüller, Hans

    2014-10-01

    The aim of the present work is a detailed analysis of aerosol columnar optical depth as a tool to determine near-surface aerosol extinction in Reno, Nevada, USA, during the summer of 2012. Ground and columnar aerosol optical properties were obtained by use of in situ Photoacoustic and Integrated Nephelometer and Cimel CE-318 Sun photometer instruments, respectively. Both techniques showed that seasonal weather changes and fire plumes had enormous influence on local aerosol optics. The apparent optical height followed the shape but not magnitude of the development of the convective boundary layer when fire conditions were not present. Back trajectory analysis demonstrated that a local flow known as the Washoe Zephyr circulation often induced aerosol transport from Northern California over the Sierra Nevada Mountains that increased the aerosol optical depth at 500 nm during afternoons when compared with mornings. Aerosol fine mode fraction indicated that afternoon aerosols in June and July and fire plumes in August were dominated by submicron particles, suggesting upwind urban plume biogenically enhanced evolution toward substantial secondary aerosol formation. This fine particle optical depth was inferred to be beyond the surface, thereby complicating use of remote sensing measurements for near-ground aerosol extinction measurements. It is likely that coarse mode depletes fine mode aerosol near the surface by coagulation and condensation of precursor gases.

  8. Development of a double-layered ceramic filter for aerosol filtration at high-temperatures: the filter collection efficiency.

    PubMed

    de Freitas, Normanda L; Gonçalves, José A S; Innocentini, Murilo D M; Coury, José R

    2006-08-25

    The performance of double-layered ceramic filters for aerosol filtration at high temperatures was evaluated in this work. The filtering structure was composed of two layers: a thin granular membrane deposited on a reticulate ceramic support of high porosity. The goal was to minimize the high pressure drop inherent of granular structures, without decreasing their high collection efficiency for small particles. The reticulate support was developed using the technique of ceramic replication of polyurethane foam substrates of 45 and 75 pores per inch (ppi). The filtering membrane was prepared by depositing a thin layer of granular alumina-clay paste on one face of the support. Filters had their permeability and fractional collection efficiency analyzed for filtration of an airborne suspension of phosphatic rock in temperatures ranging from ambient to 700 degrees C. Results revealed that collection efficiency decreased with gas temperature and was enhanced with filtration time. Also, the support layer influenced the collection efficiency: the 75 ppi support was more effective than the 45 ppi. Particle collection efficiency dropped considerably for particles below 2 microm in diameter. The maximum collection occurred for particle diameters of approximately 3 microm, and decreased again for diameters between 4 and 8 microm. Such trend was successfully represented by the proposed correlation, which is based on the classical mechanisms acting on particle collection. Inertial impaction seems to be the predominant collection mechanism, with particle bouncing/re-entrainment acting as detachment mechanisms.

  9. Analysis of vertical distributions and effective flight layers of insects: three-dimensional simulation of flying insects and catch at trap heights

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mean height and standard deviation (SD) of flight is calculated for over 100 insect species from their catches on trap heights reported in the literature. The iterative equations for calculating mean height and SD are presented. The mean flight height for 95% of the studies varied from 0.17 to 5...

  10. Aerosol pattern correlation techniques of wind measurement

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W.

    1985-01-01

    This paper reviews the current status of lidar image correlation techniques of remote wind measurement. It also examines the potential use of satellite borne lidar global wind measurements using this approach. Lidar systems can easily detect spatial variations in the volume scattering cross section of naturally occurring aerosols. Lidar derived RHI, PPI and range-time displays of aerosol backscatter have been extensively employed in the study of atmospheric structure. Descriptions of this type of data can be obtained in many references including Kunkel et al. (1977), Kunkel et al. (1980), Boers et al. (1984), Uthe et al. (1980), Melfi et al. (1985) and Browell et al. (1983). It is likely that the first space-borne lidars for atmospheric studies will observe aerosol backscatter to measure parameters such as boundary layer depth and cloud height. This paper examines the potential application of these relatively simple aerosol backscatter lidars to global wind measurements.

  11. Complex vertical layering and mixing of aerosols over the eastern Mediterranean: active and passive remote sensing at the Cyprus University of Technology

    NASA Astrophysics Data System (ADS)

    Mamouri, R.-E.; Nisantzi, A.; Hadjimitsis, D. G.; Ansmann, A.; Schwarz, A.; Basart, S.; Baldasano, J. M.

    2013-08-01

    Aerosols can have a complicated influence on climate conditions, directly as well as indirectly via cloud formation. The southeastern Mediterranean region can be characterized as a cross road of aerosols originating from European, Asian and African continents. Complex vertical aerosol distributions are frequently detected over Cyprus by means of active remote sensing. Observations of such complex aerosol layering and comparison of the measurements with aerosol products of regional and global atmospheric transport models are required to improve our understanding of life cycles of aerosol mixtures and their impact on climate as well as on satellite remote sensing products. In this study, a case of an intense desert dust outbreak from Syria and Saudi Arabia towards the eastern Mediterranean in September 2011 is presented. The observations used in this study were performed with a 532-nm polarization Lidar and a sun/sky AERONET photometer operated at 8 channels from 340 to 1640 nm wavelength. Both instruments belong to remote sensing station of the Cyprus Technical University at Limassol, Cyprus (34°N, 33°E). The lofted dust plume was doped with air masses that crossed sources of biomass burning smoke and anthropogenic pollution. In addition, the shallow marine boundary layer over the Mediterranean Sea and over Limassol became mixed with the anthropogenic haze by sea breeze circulations. The case study demonstrates the potential of combined lidar/photometer observations to deliver detailed vertically resolved information of the aerosol characteristics in terms of particle optical and microphysical properties, separately for the spherical particle fraction as well as for the non-spherical aerosol mode.

  12. Aerosol optical depth, aerosol composition and air pollution during summer and winter conditions in Budapest.

    PubMed

    Alföldy, B; Osán, J; Tóth, Z; Török, S; Harbusch, A; Jahn, C; Emeis, S; Schäfer, K

    2007-09-20

    The dependence of aerosol optical depth (AOD) on air particulate concentrations in the mixing layer height (MLH) was studied in Budapest in July 2003 and January 2004. During the campaigns gaseous (CO, SO(2), NO(x), O(3)), solid components (PM(2.5), PM(10)), as well as ionic species (ammonium, sulfate and nitrate) were measured at several urban and suburban sites. Additional data were collected from the Budapest air quality monitoring network. AOD was measured by a ground-based sun photometer. The mixing layer height and other common meteorological parameters were recorded. A linear relationship was found between the AOD and the columnar aerosol burden; the best linear fit (R(2)=0.96) was obtained for the secondary sulfate aerosol due to its mostly homogeneous spatial distribution and its optically active size range. The linear relationship is less pronounced for the PM(2.5) and PM(10) fractions since local emissions are very heterogeneous in time and space. The results indicate the importance of the mixing layer height in determining pollutant concentrations. During the winter campaign, when the boundary layer decreases to levels in between the altitudes of the sampling stations, measured concentrations showed significant differences due to different local sources and long-range transport. In the MLH time series unexpected nocturnal peaks were observed. The nocturnal increase of the MLH coincided with decreasing concentrations of all pollutants except for ozone; the ozone concentration increase indicates nocturnal vertical mixing between different air layers.

  13. Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley.

    PubMed

    Rahul, P R C; Bhawar, R L; Ayantika, D C; Panicker, A S; Safai, P D; Tharaprabhakaran, V; Padmakumari, B; Raju, M P

    2014-01-14

    First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30(th) August, 4(th) and 6(th) September 2009 over Guwahati (26° 11'N, 91° 44'E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4-6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region.

  14. Double blanket effect caused by two layers of black carbon aerosols escalates warming in the Brahmaputra River Valley

    PubMed Central

    Rahul, P. R. C.; Bhawar, R. L.; Ayantika, D. C.; Panicker, A. S.; Safai, P. D.; Tharaprabhakaran, V.; Padmakumari, B.; Raju, M. P.

    2014-01-01

    First ever 3-day aircraft observations of vertical profiles of Black Carbon (BC) were obtained during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX) conducted on 30th August, 4th and 6th September 2009 over Guwahati (26°11′N, 91°44′E), the largest metropolitan city in the Brahmaputra River Valley (BRV) region. The results revealed that apart from the surface/near surface loading of BC due to anthropogenic processes causing a heating of 2 K/day, the large-scale Walker and Hadley atmospheric circulations associated with the Indian summer monsoon help in the formation of a second layer of black carbon in the upper atmosphere, which generates an upper atmospheric heating of ~2 K/day. Lofting of BC aerosols by these large-scale circulating atmospheric cells to the upper atmosphere (4–6 Km) could also be the reason for extreme climate change scenarios that are being witnessed in the BRV region. PMID:24419075

  15. Using the OMI aerosol index and absorption aerosol optical depth to evaluate the NASA MERRA Aerosol Reanalysis

    NASA Astrophysics Data System (ADS)

    Buchard, V.; da Silva, A. M.; Colarco, P. R.; Darmenov, A.; Randles, C. A.; Govindaraju, R.; Torres, O.; Campbell, J.; Spurr, R.

    2015-05-01

    A radiative transfer interface has been developed to simulate the UV aerosol index (AI) from the NASA Goddard Earth Observing System version 5 (GEOS-5) aerosol assimilated fields. The purpose of this work is to use the AI and aerosol absorption optical depth (AAOD) derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications Aerosol Reanalysis (MERRAero). MERRAero is based on a version of the GEOS-5 model that is radiatively coupled to the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) aerosol module and includes assimilation of aerosol optical depth (AOD) from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. Since AI is dependent on aerosol concentration, optical properties and altitude of the aerosol layer, we make use of complementary observations to fully diagnose the model, including AOD from the Multi-angle Imaging SpectroRadiometer (MISR), aerosol retrievals from the AErosol RObotic NETwork (AERONET) and attenuated backscatter coefficients from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) mission to ascertain potential misplacement of plume height by the model. By sampling dust, biomass burning and pollution events in 2007 we have compared model-produced AI and AAOD with the corresponding OMI products, identifying regions where the model representation of absorbing aerosols was deficient. As a result of this study over the Saharan dust region, we have obtained a new set of dust aerosol optical properties that retains consistency with the MODIS AOD data that were assimilated, while resulting in better agreement with aerosol absorption measurements from OMI. The analysis conducted over the southern African and South American biomass burning regions indicates that revising the spectrally dependent aerosol absorption properties in the near-UV region improves the modeled-observed AI comparisons

  16. Scattering and absorption properties of near-surface aerosol over Gangetic-Himalayan region: the role of boundary layer dynamics and long-range transport

    NASA Astrophysics Data System (ADS)

    Dumka, U. C.; Kaskaoutis, D. G.; Srivastava, M. K.; Devara, P. C. S.

    2014-08-01

    Knowledge of light scattering and absorption properties of atmospheric aerosols is of vital importance in evaluating their types, sources and radiative forcing. This is of particular interest over the Gangetic-Himalayan (GH) region due to large aerosol loading over the plains and the uplift over the Himalayan range causing serious effects on atmospheric heating, glaciology and monsoon circulation. In this respect, Ganges Valley Aerosol Experiment (GVAX) was initiated over the region aiming to examine the aerosol properties, source regions, uplift mechanisms and aerosol-cloud interactions. The present study examines the temporal (monthly, seasonal) evolution of scattering (σsp) and absorption (σap) coefficients, their wavelength dependence, and the role of the Indo-Gangetic plains (IGP), boundary-layer dynamics (BLD) and long-range transport (LRT) in the aerosol uplift over the Himalayas. The measurements are performed at the elevated site Nainital via the Atmospheric Radiation Measurement Mobile Facility including several instruments (Nephelometer, Particle Soot Absorption Photometer, etc.) during June 2011 to March 2012. The σsp and σap exhibit a pronounced seasonal variation with monsoon low and post-monsoon (November) high, while the scattering wavelength exponent exhibits higher values during monsoon, in contrast to the absorption Ångström exponent which maximizes in December-March. The analysis is performed separately for particles bellow 10 and 1μm in diameter in order to examine the influence of the particle size on optical properties. The elevated-background measuring site provides the advantage of examining the LRT of natural and anthropogenic aerosols from the IGP and southwest Asia and the role of BLD in the aerosol lifting processes, while the aerosols are found to be well-mixed and aged-type dominant.

  17. Observational evidence for aerosol invigoration in shallow cumulus downstream of Mount Kilauea

    NASA Astrophysics Data System (ADS)

    Mace, G. G.; Abernathy, A. C.

    2016-03-01

    Knowledge of how marine boundary layer (MBL) shallow cumulus clouds respond to changes in aerosol is central to understanding how MBL clouds modulate the climate system. Mount Kilauea on the island of Hawaii began erupting in 2008 injecting substantial SO2 into the marine boundary layer creating a unique natural laboratory. Examining data from approximately 600 passes of the A-Train downstream of Mount Kilauea over a 3 year period and separating data into aerosol optical depth quartiles, we find an unambiguous increase in marine boundary cloud top height and an increase in surface wind speed as aerosol increases while the radar reflectivity does not change substantially. We conclude that increased aerosols may have caused invigoration of the MBL clouds. Additionally, we find that increases in sub 1 km cloud fraction combined with increasing aerosol explain the increased visible reflectance suggesting that evidence for the so-called first aerosol indirect effect should be reexamined.

  18. 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

  19. A Simple Apparatus for the Injection of Lithium Aerosol into the Scrape-Off Layer of Fusion Research Devices

    SciTech Connect

    D. K. Mansfield, A.L Roquemore, H. Schneider, J. Timberlake, H. Kugel, M.G. Bell and the NSTX Research Team

    2010-10-11

    A simple device has been developed to deposit elemental lithium onto plasma facing components in the National Spherical Torus Experiment. Deposition is accomplished by dropping lithium powder into the plasma column. Once introduced, lithium particles quickly become entrained in scrape-off layer flow as an evaporating aerosol. Particles are delivered through a small central aperture in a computer-controlled resonating piezoelectric disk on which the powder is supported. The device has been used to deposit lithium both during discharges as well as prior to plasma breakdown. Clear improvements to plasma performance have been demonstrated. The use of this apparatus provides flexibility in the amount and timing of lithium deposition and, therefore, may benefit future fusion research devices.

  20. Impact of Tropospheric Aerosol Absorption on Ozone Retrieval from buv Measurements

    NASA Technical Reports Server (NTRS)

    Torres, O.; Bhartia, P. K.

    1998-01-01

    The impact of tropospheric aerosols on the retrieval of column ozone amounts using spaceborne measurements of backscattered ultraviolet radiation is examined. Using radiative transfer calculations, we show that uv-absorbing desert dust may introduce errors as large as 10% in ozone column amount, depending on the aerosol layer height and optical depth. Smaller errors are produced by carbonaceous aerosols that result from biomass burning. Though the error is produced by complex interactions between ozone absorption (both stratospheric and tropospheric), aerosol scattering, and aerosol absorption, a surprisingly simple correction procedure reduces the error to about 1%, for a variety of aerosols and for a wide range of aerosol loading. Comparison of the corrected TOMS data with operational data indicates that though the zonal mean total ozone derived from TOMS are not significantly affected by these errors, localized affects in the tropics can be large enough to seriously affect the studies of tropospheric ozone that are currently undergoing using the TOMS data.

  1. The VOCALS Regional Experiment: Aerosol-Cloud-Precipitation Interactions in Marine Boundary Layer Cloud

    NASA Astrophysics Data System (ADS)

    Wood, R.

    2012-12-01

    Robert Wood, C.S. Bretherton, C. R. Mechoso, R. A. Weller, B. J. Huebert, H. Coe, B. A. Albrecht, P. H. Daum, D. Leon, A. Clarke, P. Zuidema, C. W. Fairall, G. Allen, S. deSzoeke, G. Feingold, J. Kazil, S. Yuter, R. George, A. Berner, C. Terai, G. Painter, H. Wang, M. Wyant, D. Mechem The VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) is an international field program designed to make observations of poorly understood but critical components of the coupled climate system of the southeast Pacific (SEP), a region dominated by strong coastal upwelling, extensive cold SSTs, and home to the largest subtropical stratocumulus deck on Earth. VOCALS-REx took place during October and November 2008 and involved five research aircraft, two ships and two surface sites in northen Chile. A central theme of VOCALS-REx is the improved understanding of links between aerosols, clouds and precipitation and their impacts on marine stratocumulus radiative properties. In this presentation, we will present a synthesis of results from VOCALS-REx focusing on the following questions: (a) how are aerosols, clouds and precipitation inter-related in the SEP region? (b) what microphysical-macrophysical interactions are necessary for the formation and maintenance of open cells? (c) how do cloud and MBL properties change across the strong microphysical gradients from the South American coast to the remote ocean?

  2. Regional aerosol properties: Comparisons of boundary layer measurements from ACE 1, ACE 2, Aerosols99, INDOEX, ACE Asia, TARFOX, and NEAQS

    NASA Astrophysics Data System (ADS)

    Quinn, Patricia K.; Bates, Timothy S.

    2005-07-01

    Means and variability of aerosol chemical composition and optical properties are compared for the first and second Aerosol Characterization Experiments (ACE 1 and ACE 2), a cruise across the Atlantic (Aerosols99), the Indian Ocean Experiment (INDOEX), the Asian Aerosol Characterization Experiment (ACE Asia), the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX), and the New England Air Quality Study (NEAQS). These experiments were focused either on the remote marine atmosphere (ACE 1) or areas downwind of continental aerosol source regions including western Europe, North America, Africa, India, and Asia. Presented here are size-segregated concentrations of aerosol mass, sea salt, non-sea-salt (nss) SO4=, NH4+, NO3-, dust, organic carbon (OC), elemental carbon (EC), and nss K+, as well as mass ratios that are commonly used to identify aerosol sources and to assess aerosol processing (Cl- to Na+, OC to nss SO4=, EC to total carbon (TC), EC to nss SO4=, nss K+ to EC, Fe to Al, and Si to Al). Optical properties that are compared include size-segregated scattering, backscattering, and absorption coefficients, and single-scattering albedo at 550 nm. Size-segregated mass scattering and mass absorption efficiencies for the total aerosol and mass extinction efficiencies for the dominant chemical components also are compared. In addition, we present the contribution to light extinction by the dominant chemical components for each region. All data are based on shipboard measurements performed at a relative humidity of 55 ± 5%. Scattering coefficients and single-scattering albedos also are reported at ambient relative humidity (RH) using published values of f(RH). Finally, aerosol optical depths from each region are compared. Identical sampling protocols were used in all experiments in order to eliminate sampling biases and to make the data directly comparable. Major findings include (1) nss SO4= makes up only 16 to 46% of the submicron aerosol mass

  3. Clouds, Aerosol, and Precipitation in the Marine Boundary Layer: Analysis of Results from the ARM Mobile Facility Deployment to the Azores (2009/2010)

    SciTech Connect

    Wood, Robert

    2013-05-31

    The project focuses upon dataset analysis and synthesis of datasets from the AMF deployment entitled “Clouds, Aerosols, and Precipitation in the Marine Boundary Layer (CAP-MBL)” at Graciosa Island in the Azores. Wood is serving a PI for this AMF deployment.

  4. Validation of ash optical depth and layer height retrieved from passive satellite sensors using EARLINET and airborne lidar data: the case of the Eyjafjallajökull eruption

    NASA Astrophysics Data System (ADS)

    Balis, Dimitris; Koukouli, Maria-Elissavet; Siomos, Nikolaos; Dimopoulos, Spyridon; Mona, Lucia; Pappalardo, Gelsomina; Marenco, Franco; Clarisse, Lieven; Ventress, Lucy J.; Carboni, Elisa; Grainger, Roy G.; Wang, Ping; Tilstra, Gijsbert; van der A, Ronald; Theys, Nicolas; Zehner, Claus

    2016-05-01

    The vulnerability of the European airspace to volcanic eruptions was brought to the attention of the public and the scientific community by the 2010 eruptions of the Icelandic volcano Eyjafjallajökull. As a consequence of this event, ash concentration thresholds replaced the "zero tolerance to ash" rule, drastically changing the requirements on satellite ash retrievals. In response to that, the ESA funded several projects aiming at creating an optimal end-to-end system for volcanic ash plume monitoring and prediction. Two of them, namely the SACS-2 and SMASH projects, developed and improved dedicated satellite-derived ash plume and sulfur dioxide level assessments. The validation of volcanic ash levels and height extracted from the GOME-2 and IASI instruments on board the MetOp-A satellite is presented in this work. EARLINET lidar measurements are compared to different satellite retrievals for two eruptive episodes in April and May 2010. Comparisons were also made between satellite retrievals and aircraft lidar data obtained with the UK's BAe-146-301 Atmospheric Research Aircraft (managed by the Facility for Airborne Atmospheric Measurements, FAAM) over the United Kingdom and the surrounding regions. The validation results are promising for most satellite products and are within the estimated uncertainties of each of the comparative data sets, but more collocation scenes would be desirable to perform a comprehensive statistical analysis. The satellite estimates and the validation data sets are better correlated for high ash optical depth values, with correlation coefficients greater than 0.8. The IASI retrievals show a better agreement concerning the ash optical depth and ash layer height when compared with the ground-based and airborne lidar data.

  5. Results from the ICOS Fall 2008 intensive campaign for boundary layer height detection and greenhouse gases vertical distribution study at Orleans forest, France.

    NASA Astrophysics Data System (ADS)

    Xueref-Remy, I.; Loaec, S.; Feist, D.; Lavric, J.-V.; Roininen, R.; Romanini, D.; Delmotte, M.; Schmidt, M.; Ramonet, M.; Ciais, P.

    2009-04-01

    An intensive field campaign of three weeks has been carried out in October 2008 in Orléans Forest, France, dedicated 1/ to the assessment of different instrument types for retrieval of the continental boundary layer (CBL) height and 2/ to the study of vertical distribution and diurnal cycle of atmospheric greenhouse gases (GHG). This campaign occured in the framework of ICOS (Integrated Carbon Observing System) which is one of the infrastructures selected in the ESFRI roadmap. ICOS aims at getting a homogeneous and dense network for greenhouse gases monitoring in Europe operating for the next 25 years. Launched in 2008, ICOS is currently in its preliminary phase (until 2012). One current mandatory step is to identify the instrumentation that will be deployed in the stations of the network. All stations will be equiped with GHG analysers, as well as CBL probes to allow calculation of GHG budget in the CBL. During the campaign, one Lidar, one ceilometer and one cloud telemeter have been intercompared for CBL height detection. Radiosoundings have been carried out simultaneously to serve as a reference for this intercomparison. In parallel, GHG (and especially CO2) in-situ measurements have been recorded at four altitude levels on a tall tower (5m, 50m, 100m and 180m), between 100m and 3000m using in-situ and flask sampling instruments onboard a small aircraft, and between the surface and 200m using a probe attached to a captive balloon deployed by Meteo France. We will hereby present ICOS, the test site, the instrumentation and selected results from the intensive campaign.

  6. Single-Particle Measurements of Midlatitude Black Carbon and Light-Scattering Aerosols from the Boundary Layer to the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Schwartz, J. P.; Gao, R. S.; Fahey, D. W.; Thomson, D. S.; Watts, L. A.; Wilson, J. C.; Reeves, J. M.; Darbeheshti, M.; Baumgardner, D. G.; Kok, G. L.; Chung, S. H.; Schulz, M.; Hendricks, J.; Lauer, A.; Kaercher, B.; Slowik, J. G.; Rosenlof, K. H.; Thompson, T. L.; Langford, A. O.; Loewenstein, M.; Aikin, K. C.

    2006-01-01

    A single-particle soot photometer (SP2) was flown on a NASA WB-57F high-altitude research aircraft in November 2004 from Houston, Texas. The SP2 uses laser-induced incandescence to detect individual black carbon (BC) particles in an air sample in the mass range of approx.3-300 fg (approx.0.15-0.7 microns volume equivalent diameter). Scattered light is used to size the remaining non-BC aerosols in the range of approx.0.17-0.7 microns diameter. We present profiles of both aerosol types from the boundary layer to the lower stratosphere from two midlatitude flights. Results for total aerosol amounts in the size range detected by the SP2 are in good agreement with typical particle spectrometer measurements in the same region. All ambient incandescing particles were identified as BC because their incandescence properties matched those of laboratory-generated BC aerosol. Approximately 40% of these BC particles showed evidence of internal mixing (e.g., coating). Throughout profiles between 5 and 18.7 km, BC particles were less than a few percent of total aerosol number, and black carbon aerosol (BCA) mass mixing ratio showed a constant gradient with altitude above 5 km. SP2 data was compared to results from the ECHAM4/MADE and LmDzT-INCA global aerosol models. The comparison will help resolve the important systematic differences in model aerosol processes that determine BCA loadings. Further intercomparisons of models and measurements as presented here will improve the accuracy of the radiative forcing contribution from BCA.

  7. 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

  8. Planetary Boundary Layer from AERI and MPL

    SciTech Connect

    Sawyer, Virginia

    2014-02-13

    The distribution and transport of aerosol emitted to the lower troposphere is governed by the height of the planetary boundary layer (PBL), which limits the dilution of pollutants and influences boundary-layer convection. Because radiative heating and cooling of the surface strongly affect the PBL top height, it follows diurnal and seasonal cycles and may vary by hundreds of meters over a 24-hour period. The cap the PBL imposes on low-level aerosol transport makes aerosol concentration an effective proxy for PBL height: the top of the PBL is marked by a rapid transition from polluted, well-mixed boundary-layer air to the cleaner, more stratified free troposphere. Micropulse lidar (MPL) can provide much higher temporal resolution than radiosonde and better vertical resolution than infrared spectrometer (AERI), but PBL heights from all three instruments at the ARM SGP site are compared to one another for validation. If there is agreement among them, the higher-resolution remote sensing-derived PBL heights can accurately fill in the gaps left by the low frequency of radiosonde launches, and thus improve model parameterizations and our understanding of boundary-layer processes.

  9. Global median model of the F2-layer peak height based on ionospheric radio-occultation and ground-based Digisonde observations

    NASA Astrophysics Data System (ADS)

    Shubin, V. N.

    2015-09-01

    In this article, we present a global median model of the ionospheric F2-layer peak height (hmF2), which we named Satellite and Digisonde Model of the F2 layer (SDMF2). This model is based on the radio-occultation data of the satellite missions CHAMP (2001-2008), GRACE (2007-2011), COSMIC (2006-2012) as well as the ionospheric sounding data from the 62 Earth-based Digisonde sounders (1987-2012). As the input parameters, the model uses the year, month and time UT as well as the geographic coordinates and F10.7 index averaged over the 3 Sun rotations (F10.7A). The SDMF2 model is based on the spherical functions decomposition with the 12 harmonics for the longitude and the 8 ones for the modified dip latitude (MODIP). For the diurnal variations, we used the 3 Fourier harmonics. We assumed that the dependency of hmF2 on F10.7A index is logarithmic. The model accurately reproduces both the spatial and temporal behavior of the monthly hmF2 median. The root-mean-square (RMS) and the mean relative deviations (MRD) from the original data are MRD ∼ 3.7%, RMS ∼ 14.3 km and MRD ∼ 5.4%, RMS ∼ 23.4 km for the periods of low and high solar activity, respectively. The large initial dataset allows achieving the higher accuracy than International Reference Ionosphere model (IRI), and this is confirmed by comparing the SDMF2 model with independent data.

  10. Tropospheric aerosol profile information from high-resolution oxygen A-band measurements from space

    NASA Astrophysics Data System (ADS)

    Geddes, A.; Bösch, H.

    2015-02-01

    Aerosols are an important factor in the Earth climatic system and they play a key role in air quality and public health. Observations of the oxygen A-band at 760 nm can provide information on the vertical distribution of aerosols from passive satellite sensors that can be of great interest for operational monitoring applications with high spatial coverage if the aerosol information is obtained with sufficient precision, accuracy and vertical resolution. To address this issue, retrieval simulations of the aerosol vertical profile retrieval from O2 A-band observations by GOSAT, the upcoming Orbiting Carbon Observatory-2 (OCO-2) and Sentinel 5-P missions, and the proposed CarbonSat mission have been carried out. Precise retrievals of aerosol optical depth (AOD) within the boundary layer were found to favour low-resolution, high signal-to-noise instruments such as Sentinel-5 P, whereas higher-resolution instruments such as OCO-2 showed greater performance at higher altitudes and in information content above the boundary layer. Retrieval of the AOD in the 0-2 km range with precision appears difficult from all studied instruments and the retrieval errors typically exceed a value of 0.05 for AODs up to 0.3. Constraining the surface albedo is a promising and effective way of improving the retrieval of aerosol, but the accuracy of the required prior knowledge is very high. Due to the limited information content of the aerosol profile retrieval, the use of a parameterised aerosol distribution is assessed, and we show that the AOD and height of an aerosol layer can be retrieved well if the aerosol layer is uplifted to the free troposphere; however, errors are often large for aerosol layers in the boundary layer. Additional errors are introduced by incorrect assumptions on surface pressure and aerosol mixture, which can both bias retrieved AOD and height by up to 45%. In addition, assumptions of the boundary layer temperature are found to yield an additional error of up to 8

  11. Precipitable water as a predictor of LCL height

    NASA Astrophysics Data System (ADS)

    Murugavel, P.; Malap, N.; Balaji, B.; Mehajan, R. K.; Prabha, T. V.

    2016-08-01

    Based on the precipitable water observations easily available from in situ and remote sensing sensors, a simple approach to define the lifting condensation level (LCL) is proposed in this study. High-resolution radiosonde and microwave radiometer observations over peninsular Indian region during the Cloud Aerosol Interaction and Precipitation Enhancement Experiment Integrated Ground Observational Campaign (CAIPEEX-IGOC) during the monsoon season of 2011 are used to illustrate the unique relationship. The inferences illustrate a linear relationship between the precipitable water (PW) and the LCL temperature. This relationship is especially valuable because PW is easily available as a derived parameter from various remote sensing and ground-based observations. Thus, it could be used to estimate the LCL height and perhaps also the boundary layer height. LCL height and PW correlations are established from historical radiosonde data (1984-2012). This finding could be used to illustrate the boundary layer-cloud interactions during the monsoon and is important for parameterization of boundary layer clouds in numerical models. The relationships are illustrated to be robust and seem promising to get reasonable estimates of the LCL height over other locations as well using satellite observations of PW.

  12. Stratospheric sulfate aerosol in and near the Northern Hemisphere polar vortex - The morphology of the sulfate layer, multimodal size distributions, and the effect of denitrification

    NASA Technical Reports Server (NTRS)

    Wilson, J. G.; Stolzenburg, M. R.; Clark, W. E.; Loewenstein, M.; Ferry, G. V.; Chan, K. R.; Kelly, K. K.

    1992-01-01

    Measurements were made of stratospheric sulfate aerosols using a passive cavity aerosol spectrometer and a condensation nucleus counter on a NASA ER-2 aircraft in the Airborne Arctic Stratospheric Experiment of 1989. The problems of representative and accurate sampling and particle evaporation were explicitly addressed in the design of the inlets and reduction of the data. The measurements suggest that the sulfate aerosol is bimodal in the polar vortex above the mass mixing ratio maximum in the sulfate layer. It appears that a nuclei mode of small, newly formed particles exists in this region. A stronger case is made for a nuclei mode in the upper few kilometers of the troposphere and in the lower few kilometers of the stratosphere. This mode is probably a global phenomenon occurring in all seasons. Comparison of denitrified and nondenitrified air suggests that denitrification removes some of the larger sulfate particles.

  13. Size distribution, composition and origin of the submicron aerosol in the marine boundary layer during the eastern Mediterranean "SUB-AERO" experiment

    NASA Astrophysics Data System (ADS)

    Eleftheriadis, K.; Colbeck, I.; Housiadas, C.; Lazaridis, M.; Mihalopoulos, N.; Mitsakou, C.; Smolík, J.; Ždímal, V.

    A period of intensive physical and chemical aerosol characterisation measurements was held over 5 days during July 2000 as part of the European SUB-AERO experiment.. Concurrent measurements were performed at the Finokalia remote coastal site on the island of Crete (Greece) and onboard the R/V " Aegaeon" which cruised in south part of the Aegean Sea northwards of Crete. The objective of the study was to investigate the spatial and temporal variability of microphysical parameters of the submicron aerosol and their dependence on airmass origin and chemical composition. The results reflect the submicron aerosol properties during airmass transport from the north including Europe and the Balkans and are in line with other studies on the aerosol properties of polluted continental air entering the marine boundary layer (MBL). Concentrations of submicron particulate matter (PM) mass were relatively higher at sea (20 μg m -3) compared to the coastal site (16 μg m -3). Concentrations of both organic carbon and sulphate, being the major water soluble component, were also higher at sea than at land. The high concentrations of ammonium and those of the water soluble organics, such as oxalate, can be attributed to emissions from mainland forest fires. The submicron aerosol number size distribution was unimodal with mobility mean diameters ( dg) ranging from 98 to 144 μm and standard deviations ( σg) from 1.56 to 1.9. Aerosol number concentrations at Finokalia were at least 50% lower especially when R/V Aegaeon sampled polluted air, but the modal parameters of the size distribution were very similar ( dg: 111-120, σg: 1.55-1.91). The surface MBL, under these conditions, was an aerosol rich environment where aerosol particles were transported both by the surface wind, advected from higher layers, chemically processed by interactions with gaseous precursors and physically altered by water vapour. The number to volume ratio for the submicrometer aerosol fraction reflected the

  14. Mass spectrometry of interfacial layers during fast aqueous aerosol/ozone gas reactions of atmospheric interest

    NASA Astrophysics Data System (ADS)

    Enami, S.; Vecitis, C. D.; Cheng, J.; Hoffmann, M. R.; Colussi, A. J.

    2008-04-01

    The oxidations of sulfite and iodide in the interfacial layers of aqueous microdroplets exposed to O 3(g) for 1 ms are investigated by online mass spectrometry of the electrostatically ejected anions. S(IV) oxidation losses in Na 2SO 3 microdroplets are proportional to [S(IV)] [O 3(g)] up to ˜90% conversion. I - is more abundant than HSO3- in the interfacial layers of equimolar (Na 2SO 3 + NaI) microdroplets and ˜3 times more reactive than HSO3- toward O 3(aq) in bulk solution, but it is converted withminimalloss to I3- and IO3- plus a persistent ISO3- intermediate. These observations reveal unanticipated interfacial gradients, reactivity patterns and transport phenomena that had not been taken into account in previous treatments of fast gas-liquid reactions.

  15. Aerosol optical properties in the southeastern United States in summer - Part 2: Sensitivity of aerosol optical depth to relative humidity and aerosol parameters

    NASA Astrophysics Data System (ADS)

    Brock, Charles A.; Wagner, Nicholas L.; Anderson, Bruce E.; Beyersdorf, Andreas; Campuzano-Jost, Pedro; Day, Douglas A.; Diskin, Glenn S.; Gordon, Timothy D.; Jimenez, Jose L.; Lack, Daniel A.; Liao, Jin; Markovic, Milos Z.; Middlebrook, Ann M.; Perring, Anne E.; Richardson, Matthews S.; Schwarz, Joshua P.; Welti, Andre; Ziemba, Luke D.; Murphy, Daniel M.

    2016-04-01

    Aircraft observations of meteorological, trace gas, and aerosol properties were made between May and September 2013 in the southeastern United States (US). Regionally representative aggregate vertical profiles of median and interdecile ranges of the measured parameters were constructed from 37 individual aircraft profiles made in the afternoon when a well-mixed boundary layer with typical fair-weather cumulus was present (Wagner et al., 2015). We use these 0-4 km aggregate profiles and a simple model to calculate the sensitivity of aerosol optical depth (AOD) to changes in dry aerosol mass, relative humidity, mixed-layer height, the central diameter and width of the particle size distribution, hygroscopicity, and dry and wet refractive index, while holding the other parameters constant. The calculated sensitivity is a result of both the intrinsic sensitivity and the observed range of variation in these parameters. These observationally based sensitivity studies indicate that the relationship between AOD and dry aerosol mass in these conditions in the southeastern US can be highly variable and is especially sensitive to relative humidity (RH). For example, calculated AOD ranged from 0.137 to 0.305 as the RH was varied between the 10th and 90th percentile profiles with dry aerosol mass held constant. Calculated AOD was somewhat less sensitive to aerosol hygroscopicity, mean size, and geometric standard deviation, σg. However, some chemistry-climate models prescribe values of σg substantially larger than we or others observe, leading to potential high biases in model-calculated AOD of ˜ 25 %. Finally, AOD was least sensitive to observed variations in dry and wet aerosol refractive index and to changes in the height of the well-mixed surface layer. We expect these findings to be applicable to other moderately polluted and background continental air masses in which an accumulation mode between 0.1-0.5 µm diameter dominates aerosol extinction.

  16. Space Borne Cloud and Aerosol Measurements by the Geoscience Laser Altimeter System: Initial Results

    NASA Technical Reports Server (NTRS)

    Spinhirne, James D.; Palm, Steven P.; Hlavka, Dennis L.; Hart, William D.; Mahesh, Ashwin; Welton, Ellsworth J.

    2003-01-01

    In January 2003 the Geoscience Laser Altimeter System (GLAS) was successfully launched into orbit. Beginning in March 2003 GLAS will provide global coverage lidar measurement of the height distribution of clouds and aerosol in the atmosphere for up to five years. The characteristic and value of the unique data will be presented. The instrument is a basic backscatter lidar that operates at two wavelengths, 532 and 1064 nm. The mission data products for atmospheric observations include the calibrated, observed, attenuated backscatter cross section for cloud and aerosol; height detection for multiple cloud layers; planetary boundary layer height; cirrus and aerosol optical depth and the height distribution of aerosol and cloud scattering cross section profiles. The data is expected to significantly enhance knowledge in several areas of atmospheric science, in particular the distribution, transport and influence of atmospheric aerosol and thin clouds. Measurements of the coverage and height of polar and cirrus cloud should be significantly more accurate than previous global observations. In March and April 2003, airborne and ground based data verification experiments will be carried out. Initial results from the verification experiments and the first several months of operation will be presented.

  17. Research on aerosol profiles and parameterization scheme in Southeast China

    NASA Astrophysics Data System (ADS)

    Wang, Gang; Deng, Tao; Tan, Haobo; Liu, Xiantong; Yang, Honglong

    2016-09-01

    The vertical distribution of the aerosol extinction coefficient serves as a basis for evaluating aerosol radiative forcing and air quality modeling. In this study, MODIS AOD data and ground-based lidar extinction coefficients were employed to verify 6 years (2009-2014) aerosol extinction data obtained via CALIOP for Southeast China. The objective was mainly to provide the parameterization scheme of annual and seasonal aerosol extinction profiles. The results showed that the horizontal and vertical distributions of CALIOP extinction data were highly accurate in Southeast China. The annual average AOD below 2 km accounted for 64% of the total layer, with larger proportions observed in winter (80%) and autumn (80%) and lower proportions observed in summer (70%) and spring (59%). The AOD was maximum in the spring (0.58), followed by the autumn and winter (0.44), and reached a minimum in the summer (0.40). The near-surface extinction coefficient increased from summer, spring, autumn and winter, in that order. The Elterman profile is obviously lower than the profiles observed by CALIOP in Southeast China. The annual average and seasonal aerosol profiles showed an exponential distribution, and could be divided into two sections. Two sections exponential fitting was used in the parameterization scheme. In the first section, the aerosol scale height reached 2200 m with a maximum (3,500 m) in summer and a minimum (1,230 m) in winter, which meant that the aerosol extinction decrease with height slower in summer, but more rapidly in winter. In second section, the aerosol scale height was maximum in spring, which meant that the higher aerosol diffused in spring.

  18. Wave like signatures in aerosol optical depth and associated radiative impacts over the central Himalayan region

    SciTech Connect

    Shukla, K. K.; Phanikumar, D. V.; Kumar, K.  Niranjan; Reddy, Kishore; Kotamarthi, V. R.; Newsom, Rob K.; Ouarda, Taha B. M. J.

    2015-10-01

    In this study, we present a case study on 16 October 2011 to show the first observational evidence of the influence of short period gravity waves in aerosol transport during daytime over the central Himalayan region. The Doppler lidar data has been utilized to address the daytime boundary layer evolution and related aerosol dynamics over the site. Mixing layer height is estimated by wavelet covariance transform method and found to be ~ 0.7 km, AGL. Aerosol optical depth observations during daytime revealed an asymmetry showing clear enhancement during afternoon hours as compared to forenoon. Interestingly, Fourier and wavelet analysis of vertical velocity and attenuated backscatter showed similar 50-90 min short period gravity wave signatures during afternoon hours. Moreover, our observations showed that gravity waves are dominant within the boundary layer implying that the daytime boundary layer dynamics is playing a vital role in transporting the aerosols from surface to the top of the boundary layer. Similar modulations are also evident in surface parameters like temperature, relative humidity and wind speed indicating these waves are associated with the dynamical aspects over Himalayan region. Finally, time evolution of range-23 height indicator snapshots during daytime showed strong upward velocities especially during afternoon hours implying that convective processes through short period gravity waves plays a significant role in transporting aerosols from the nearby valley region to boundary layer top over the site. These observations also establish the importance of wave induced daytime convective boundary layer dynamics in the lower Himalayan region.

  19. Aerosol Profile Measurements from the NASA Langley Research Center Airborne High Spectral Resolution Lidar

    NASA Technical Reports Server (NTRS)

    Obland, Michael D.; Hostetler, Chris A.; Ferrare, Richard A.; Hair, John W.; Roers, Raymond R.; Burton, Sharon P.; Cook, Anthony L.; Harper, David B.

    2008-01-01

    Since achieving first light in December of 2005, the NASA Langley Research Center (LaRC) Airborne High Spectral Resolution Lidar (HSRL) has been involved in seven field campaigns, accumulating over 450 hours of science data across more than 120 flights. Data from the instrument have been used in a variety of studies including validation and comparison with the Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite mission, aerosol property retrievals combining passive and active instrument measurements, aerosol type identification, aerosol-cloud interactions, and cloud top and planetary boundary layer (PBL) height determinations. Measurements and lessons learned from the HSRL are leading towards next-generation HSRL instrument designs that will enable even further studies of aerosol intensive and extensive parameters and the effects of aerosols on the climate system. This paper will highlight several of the areas in which the NASA Airborne HSRL is making contributions to climate science.

  20. A stratospheric aerosol increase during 1981, observed by lidar over mid-Europe

    NASA Astrophysics Data System (ADS)

    Reiter, R.; Jaeger, H.; Carnuth, W.; Funk, W.

    1982-04-01

    Lidar observations of variations in the aerosol layer due to the eruptions of Mt. St. Helens and the volcano Alaid in the Kurile Islands are reported and compared. One year after the Mt. St. Helens activity the backscattering coefficient had reduced to within 10% of the values observed in the pre-eruption period. Observed peaks were found to be moving upward, eventually forming a broad aerosol layer at 15-17 km height in July, 1981. The Alaid plume moved west to east and was determined to be the cause of aerosol disturbances up to the 20 km level. Data is presented of the time variation of the aerosol quantities and the time variation of the space resolved integral backscattering. Additional data has shown that both the Mt. St. Helens and the Alaid eruptions caused only one-third the aerosol perturbations as the Fuego eruption of 1974.

  1. Lidar measurements of boundary layers, aerosol scattering and clouds during project FIFE

    NASA Technical Reports Server (NTRS)

    Eloranta, Edwin W. (Principal Investigator)

    1995-01-01

    A detailed account of progress achieved under this grant funding is contained in five journal papers. The titles of these papers are: The calculation of area-averaged vertical profiles of the horizontal wind velocity using volume imaging lidar data; Volume imaging lidar observation of the convective structure surrounding the flight path of an instrumented aircraft; Convective boundary layer mean depths, cloud base altitudes, cloud top altitudes, cloud coverages, and cloud shadows obtained from Volume Imaging Lidar data; An accuracy analysis of the wind profiles calculated from Volume Imaging Lidar data; and Calculation of divergence and vertical motion from volume-imaging lidar data. Copies of these papers form the body of this report.

  2. Aerosol profiling by calibrated ceilometer data

    NASA Astrophysics Data System (ADS)

    Geiß, Alexander; Wiegner, Matthias

    2015-04-01

    Recently, networks of automated single-wavelength backscatter lidars ("ceilometers") were implemented, primarily by weather services. As a consequence, the potential of ceilometers to quantitatively determine the spatiotemporal distribution of atmospheric aerosols was investigated, to derive mixing layer heights for air quality studies and to assess optical properties. The main issues are the limited signal-to-noise ratio and the inherent problems of the calibration. We have studied several approaches for calibrating ceilometers, based on different numerical solutions and on auxiliary data of different remote sensing techniques. As a result, the backscatter coefficient can be determined with a relative accuracy of typically 10% and a time resolution in the order of 5 minutes. This parameter is used to estimate the mixing layer height by applying different techniques of averaging and pattern recognition. In this context, it is assumed that aerosols are a good tracer for the thermodynamic stratification of the troposphere. Our algorithm is fully automated and was tested for several commercially available ceilometers. For this purpose, a simplified version for non-calibrated ceilometers, based on the so called range corrected signal, was additionally developed. We used data of the CHM15k-x ceilometer (manufactured by Jenoptik) from more than 5 years of continuous operation by the LMU-MIM in Munich (Germany) to establish climatologies of mixing layer heights (MLH), cloud cover, cloud heights and vertical profiles of the backscatter coefficient. Among others, the mean diurnal cycle and the interannual variability of the MLH for different months were determined. Ceilometer derived MLH were also used to validate different parameterization of chemistry transport models and to validate forecasts of the dispersion of aerosol layers. For the latter applications backscatter coefficients are required. That means, a calibration of the ceilometers is mandatory.

  3. Mixing-height measurement by lidar, particle counter, and rawinsonde in the Williamette Valley, Oregon

    NASA Technical Reports Server (NTRS)

    Mccormick, M. P.; Melfi, S. H.; Olsson, L. E.; Tuft, W. L.; Elliott, W. P.; Egami, R.

    1972-01-01

    The feasibility of using laser radar (lidar) to measure the spatial distribution of aerosols and water vapor in the earth's mixing or boundary layer is shown. From these data the important parameter of actual mixing height was determined, that is, the maximum height to which particulate pollutants actually mix. Data are shown for simultaneous lidar, rawinsonde, and aircraft-mounted condensation nuclei counter and temperature measurements. The synoptic meteorology is also presented. The Williamette Valley, Oregon, was chosen for the measurements because of its unique combination of meteorology, terrain, and pollutant source, along with an ongoing Oregon State University study of the natural ventilation of this valley.

  4. Vertical resolved separation of aerosol types using CALIPSO level-2 product

    NASA Astrophysics Data System (ADS)

    Giannakaki, Elina; Balis, Dimitris; Amiridis, Vassilis

    2011-11-01

    A lidar-based method was used to separate profiles of optical parameters due to different aerosol types over different European Aerosol Research LIdar NETwork (EARLINET) stations. The method makes uses of particle backscatter profiles at 532 nm and vertically resolved linear particle depolarization ratio measurements at the same wavelength. Values of particle depolarization ratio of 'pure' aerosol types (Saharan dust, biomass burning aerosols, anthropogenic aerosols, Volcanic ash aerosols) were taken from literature. Cases of CALIPSO space-borne lidar system were selected on the basis of different mixing state of the atmosphere over EARLINET stations. To identify the origin of air-masses four-day air mass back trajectories were computed using HYbrid Single-Particle Langrangian Integrated Trajectory (HYSPLIT) model, for different arrival heights, for the location and time under study was used. Also, the Dust REgional Atmospheric Modeling (DREAM) model was used to identify cases where dust from Saharan region was affecting the place under study. For our analysis we have used Atmospheric Volume Description (AVD), Cloud-Aerosol Discrimination (CAD) and extinction Quality Control (QC) flags to screen out CALIOP data. The method was applied for different horizontal resolution of 5, 25, 45 and 105 km. The height-resolved lidar results were finally compared with column-integrated products obtained with Aerosol Robotic Network Sun photometer (AERONET) in order to see to what extent Sun photometer columnar data are representative when different aerosol layers are present in the atmosphere.

  5. Analysis of aerosol properties derived from sun photometer and lidar over Dunhuang radiometric calibration site

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Jing, Yingying; Zhang, Peng; Hu, Xiuqing

    2016-05-01

    Duhuang site has been selected as China Radiation Calibration Site (CRCS) for Remote Sensing Satellite Sensors since 1996. With the economic development of Dunhuang city, the ambient of the radiation calibration field has changed in recent years. Taking into account the key role of aerosol in radiometric calibration, it is essential to investigate the aerosol optical properties over Dunhuang radiometric calibration site. In this paper, the CIMEL sun photometer (CE-318) and Mie-scattering Lidar are simultaneously used to measure aerosol optical properties in Dunhuang site. Data from aerosol-bands of sun photometer are used in a Langley method to determine spectral optical depths of aerosol. And Lidar is utilized to obtain information of vertical profile and integrated aerosol optical depths at different heights. The results showed that the aerosol optical depth at 500 nm wavelength during the in-situ measurement campaigns varied from 0.1 to 0.3 in Dunhuang site. And the observation results also indicated that high aerosol concentration layer mostly located at the height of about 2~4 km. These results implies that the aerosol concentration of atmosphere in Dunhuang was relatively small and suitable for in-flight calibration for remote sensing satellite sensors.

  6. Optical and physical characteristics of Bay of Bengal aerosols during W-ICARB: Spatial and vertical heterogeneities in the marine atmospheric boundary layer and in the vertical column

    NASA Astrophysics Data System (ADS)

    Moorthy, K. Krishna; Beegum, S. Naseema; Babu, S. Suresh; Smirnov, Alexander; John, Sherine Rachel; Kumar, K. Raghavendra; Narasimhulu, K.; Dutt, C. B. S.; Nair, Vijayakumar S.

    2010-12-01

    Analysis of the continuous and collocated measurements of columnar spectral aerosol optical depths (AODs) and mass size distributions in the marine atmospheric boundary layer (MABL) over the Bay of Bengal (BoB), carried out from 27 December 2008 to 29 January 2009 during the Winter Integrated Campaign for Aerosols, Gases and Radiation Budget (W-ICARB), revealed distinct regional features in the spatial variations of the aerosol properties in the MABL and column. In general, AODs were high over the northern and northwestern parts of the BoB, with pockets of very high values, within which the AODs were as high as ˜0.8 while the smallest values (˜0.1) were observed over the northeastern BoB, off the Myanmar and Bangladesh coasts. Interestingly, though, this region had the highest Angstrom wavelength exponent α (˜1.5), notwithstanding the generally high values that prevailed over the eastern as well as northern coastal regions of India. Back trajectory analyses revealed the significant role of the advected aerosols in the observed spatial pattern. Within the MABL, high accumulation mode mass concentrations (MA) prevailed over the entire BoB with the accumulation fraction ranging from 0.6 to 0.95, whereas very high fine-mode (r < 0.1 μm) aerosol mass fractions (˜0.8) were observed over the northeastern and western coastal BoB adjoining the Indian mainland (where α was high to very high). The vertical distributions, inferred from the columnar and MABL properties as well as from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations data, revealed better homogeneity in the northeastern and eastern BoB, whereas significant heterogeneity was seen over other regions.

  7. Estimating the direct radiative effect of absorbing aerosols overlying marine boundary layer clouds in the southeast Atlantic using MODIS and CALIOP

    NASA Astrophysics Data System (ADS)

    Meyer, Kerry; Platnick, Steven; Oreopoulos, Lazaros; Lee, Dongmin

    2013-05-01

    aerosols such as smoke strongly absorb solar radiation, particularly at ultraviolet and visible/near-infrared (VIS/NIR) wavelengths, and their presence above clouds can have considerable implications. It has been previously shown that they have a positive (i.e., warming) direct aerosol radiative effect (DARE) when overlying bright clouds. Additionally, they can cause biased passive instrument satellite retrievals in techniques that rely on VIS/NIR wavelengths for inferring the cloud optical thickness (COT) and effective radius (re) of underlying clouds, which can in turn yield biased above-cloud DARE estimates. Here we investigate Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical property retrieval biases due to overlying absorbing aerosols observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and examine the impact of these biases on above-cloud DARE estimates. The investigation focuses on a region in the southeast Atlantic Ocean during August and September (2006-2011), where smoke from biomass burning in southern Africa overlies persistent marine boundary layer stratocumulus clouds. Adjusting for above-cloud aerosol attenuation yields increases in the regional mean liquid COT (averaged over all ocean-only liquid clouds) by roughly 6%; mean re increases by roughly 2.6%, almost exclusively due to the COT adjustment in the non-orthogonal retrieval space. It is found that these two biases lead to an underestimate of DARE. For liquid cloud Aqua MODIS pixels with CALIOP-observed above-cloud smoke, the regional mean above-cloud radiative forcing efficiency (DARE per unit aerosol optical depth (AOD)) at time of observation (near local noon for Aqua overpass) increases from 50.9Wm-2AOD-1 to 65.1Wm-2AOD-1 when using bias-adjusted instead of nonadjusted MODIS cloud retrievals.

  8. Estimating the Direct Radiative Effect of Absorbing Aerosols Overlying Marine Boundary Layer Clouds in the Southeast Atlantic Using MODIS and CALIOP

    NASA Technical Reports Server (NTRS)

    Meyer, Kerry; Platnick, Steven; Oreopoulos, Lazaros; Lee, Dongmin

    2013-01-01

    Absorbing aerosols such as smoke strongly absorb solar radiation, particularly at ultraviolet and visible/near-infrared (VIS/NIR) wavelengths, and their presence above clouds can have considerable implications. It has been previously shown that they have a positive (i.e., warming) direct aerosol radiative effect (DARE) when overlying bright clouds. Additionally, they can cause biased passive instrument satellite retrievals in techniques that rely on VIS/NIR wavelengths for inferring the cloud optical thickness (COT) and effective radius (re) of underlying clouds, which can in turn yield biased above-cloud DARE estimates. Here we investigate Moderate Resolution Imaging Spectroradiometer (MODIS) cloud optical property retrieval biases due to overlying absorbing aerosols observed by Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and examine the impact of these biases on above-cloud DARE estimates. The investigation focuses on a region in the southeast Atlantic Ocean during August and September (2006-2011), where smoke from biomass burning in southern Africa overlies persistent marine boundary layer stratocumulus clouds. Adjusting for above-cloud aerosol attenuation yields increases in the regional mean liquid COT (averaged over all ocean-only liquid clouds) by roughly 6%; mean re increases by roughly 2.6%, almost exclusively due to the COT adjustment in the non-orthogonal retrieval space. It is found that these two biases lead to an underestimate of DARE. For liquid cloud Aqua MODIS pixels with CALIOP-observed above-cloud smoke, the regional mean above-cloud radiative forcing efficiency (DARE per unit aerosol optical depth (AOD)) at time of observation (near local noon for Aqua overpass) increases from 50.9Wm(sup-2)AOD(sup-1) to 65.1Wm(sup-2)AOD(sup -1) when using bias-adjusted instead of nonadjusted MODIS cloud retrievals.

  9. Assessment of 10-Year Global Record of Aerosol Products from the OMI Near-UV Algorithm

    NASA Astrophysics Data System (ADS)

    Ahn, C.; Torres, O.; Jethva, H. T.

    2014-12-01

    Global observations of aerosol properties from space are critical for understanding climate change and air quality applications. The Ozone Monitoring Instrument (OMI) onboard the EOS-Aura satellite provides information on aerosol optical properties by making use of the large sensitivity to aerosol absorption and dark surface albedo in the UV spectral region. These unique features enable us to retrieve both aerosol extinction optical depth (AOD) and single scattering albedo (SSA) successfully from radiance measurements at 354 and 388 nm by the OMI near UV aerosol algorithm (OMAERUV). Recent improvements to algorithms in conjunction with the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Atmospheric Infrared Sounder (AIRS) carbon monoxide data also reduce uncertainties due to aerosol layer heights and types significantly in retrieved products. We present validation results of OMI AOD against space and time collocated Aerosol Robotic Network (AERONET) measured AOD values over multiple stations representing major aerosol episodes and regimes. We also compare the OMI SSA against the inversion made by AERONET as well as an independent network of ground-based radiometer called SKYNET in Japan, China, South-East Asia, India, and Europe. The outcome of the evaluation analysis indicates that in spite of the "row anomaly" problem, affecting the sensor since mid-2007, the long-term aerosol record shows remarkable sensor stability. The OMAERUV 10-year global aerosol record is publicly available at the NASA data service center web site (http://disc.sci.gsfc.nasa.gov/Aura/data-holdings/OMI/omaeruv_v003.shtml).

  10. Aerosol characteristics in the UTLS region: A satellite-based study over north India

    NASA Astrophysics Data System (ADS)

    Srivastava, A. K.; Misra, A.; Kanawade, Vijay P.; Devara, P. C. S.

    2016-01-01

    Vertical profiles of aerosol backscatter coefficient and depolarization ratio, obtained from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite, were studied in the upper troposphere and lower stratosphere (UTLS) region over North India (21-30° N and 72-90° E), covering the highly polluted Indo-Gangetic Plain (IGP) for one-year period from December 2011 to November 2012. An enhanced aerosol layer was observed between 15 and 18 km altitude, in the vicinity of tropopause, with a broad layer depth of about 2 km. The aerosol layer showed strong seasonal, monthly as well as day and night time variability, with a peak value of backscatter coefficient during monsoon season (˜5.54 × 10-3 sr-1 in September). The corresponding depolarization ratio indicates anisotropic (non-spherical) nature of particles. The aerosol layer was found to be highly linked with the variability in tropopause height, showing a positive correlation between tropopause height and the height of maximum backscatter coefficient (correlation coefficient of 0.8). However, it was found to be negatively correlated with the integrated backscatter coefficient (IBC), with a correlation coefficient of 0.3. We further analyzed outgoing long-wave radiation (OLR) data during the study period to investigate the link between the observed enhanced aerosol layer in the UTLS region and prevailing deep convective activities over the study region. Low values of OLR during monsoon (about 214 W m-2) indicate the occurrence of deep convection over this region, which may cause a large-scale circulation-driven vertical transport of boundary-layer pollution into the atmosphere of UTLS region. Results may have potential implications for better understanding and assessing the chemical and radiative impacts of these aerosols in the tropical UTLS region.

  11. Aerosol source plume physical characteristics from space-based multiangle imaging

    NASA Astrophysics Data System (ADS)

    Kahn, Ralph A.; Li, W.-H.; Moroney, Catherine; Diner, David J.; Martonchik, John V.; Fishbein, Evan

    2007-06-01

    Models that assess aerosol effects on regional air quality and global climate parameterize aerosol sources in terms of amount, type, and injection height. The multiangle imaging spectroradiometer (MISR) aboard NASA's Terra satellite retrieves total column aerosol optical thickness (AOT), and aerosol type over cloud-free land and water. A stereo-matching algorithm automatically retrieves reflecting-layer altitude wherever clouds or aerosol plumes have discernable spatial contrast, with about 500-m accuracy, at 1.1-km horizontal resolution. Near-source biomass burning smoke, volcanic effluent, and desert dust plumes are observed routinely, providing information about aerosol amount, particle type, and injection height useful for modeling applications. Compared to background aerosols, the plumes sampled have higher AOT, contain particles having expected differences in Angstrom exponent, size, single-scattering albedo, and for volcanic plume and dust cloud cases, particle shape. As basic thermodynamics predicts, thin aerosol plumes lifted only by regional winds or less intense heat sources are confined to the boundary layer. However, when sources have sufficient buoyancy, the representative plumes studied tend to concentrate within discrete, high-elevation layers of local stability; the aerosol is not uniformly distributed up to a peak altitude, as is sometimes assumed in modeling. MISR-derived plume heights, along with meteorological profile data from other sources, make it possible to relate radiant energy flux observed by the moderate resolution imaging spectroradiometer (MODIS), also aboard the Terra spacecraft, to convective heat flux that plays a major role in buoyant plume dynamics. A MISR climatology of plume behavior based on these results is being developed.

  12. 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. PMID:26421659

  13. 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.

  14. Aerosols attenuating the solar radiation collected by solar tower plants: The horizontal pathway at surface level

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Ramon, Didier; Dubus, Laurent; Bourdil, Charles; Cuevas-Agulló, Emilio; Zaidouni, Taoufik; Formenti, Paola

    2016-05-01

    Aerosols attenuate the solar radiation collected by solar tower plants (STP), along two pathways: 1) the atmospheric column pathway, between the top of the atmosphere and the heliostats, resulting in Direct Normal Irradiance (DNI) changes; 2) the grazing pathway close to surface level, between the heliostats and the optical receiver. The attenuation along the surface-level grazing pathway has been less studied than the aerosol impact on changes of DNI, while it becomes significant in STP of 100 MW or more. Indeed aerosols mostly lay within the surface atmospheric layer, called the boundary layer, and the attenuation increases with the distance covered by the solar radiation in the boundary layer. In STP of 100 MW or more, the distance between the heliostats and the optical receiver becomes large enough to produce a significant attenuation by aerosols. We used measured aerosol optical thickness and computed boundary layer height to estimate the attenuation of the solar radiation at surface level at Ouarzazate (Morocco). High variabilities in aerosol amount and in vertical layering generated a significant magnitude in the annual cycle and significant inter-annual changes. Indeed the annual mean of the attenuation caused by aerosols over a 1-km heliostat-receiver distance was 3.7% in 2013, and 5.4% in 2014 because of a longest desert dust season. The monthly minimum attenuation of less than 3% was observed in winter and the maximum of more than 7% was observed in summer.

  15. A global survey of aerosol-liquid water cloud overlap based on four years of CALIPSO-CALIOP data

    NASA Astrophysics Data System (ADS)

    Devasthale, A.; Thomas, M. A.

    2010-09-01

    The presence of aerosols over highly reflective liquid water cloud tops poses a big challenge in simulating their radiative impacts. Particularly, absorbing aerosols, such as smoke, may have significant impact in such situations and even change the sign of net radiative forcing. Until now, it was not possible to obtain information on such overlap events realistically from the existing passive satellite sensors. However, the CALIOP instrument onboard NASA's CALIPSO satellite allows us to examine these events with an unprecedented accuracy. Using four years of collocated CALIPSO 5 km Aerosol and Cloud Layer Version 3 Products (June 2006-May 2010), we quantify, for the first time, the macrophysical characteristics of overlapping aerosol and water cloud layers globally. We investigate seasonal variability in these characteristics over six latitude bands to understand the hemispheric differences. We compute a) the percentage cases when such overlap is seen globally and seasonally when all aerosol types are included (AAO case) in the analysis, b) the joint histograms of aerosol layer base height and cloud layer top height, and c) the joint histograms of aerosol and cloud geometrical thicknesses in such overlap cases. We also investigate frequency of smoke aerosol-cloud overlap (SAO case). The results show a distinct seasonality in overlap frequency in both AAO and SAO cases. Globally, the frequency is highest during JJA months in AAO case, while for the SAO case, it is highest in SON months. The seasonal mean overlap frequency can regionally exceed 20% in AAO case and 10% in SAO case. There is a tendency that the vertical separation between aerosol and cloud layers increases from high to low latitude regions in the both hemispheres. In about 5-10% cases the vertical distance between aerosol and cloud layers is less than 100 m, while about in 45-60% cases it less than a kilometer in the annual means for different latitudinal bands. The frequency of occurrence of thicker

  16. Cirrus and aerosol lidar profilometer - analysis and results

    SciTech Connect

    Spinhirne, J.D.; Scott, V.S.; Reagan, J.A.; Galbraith, A.

    1996-04-01

    A cloud and aerosol lidar set from over a year of near continuous operation of a micro pulse lidar (MPL) instrument at the Cloud and Radiation Testbed (CART) site has been established. MPL instruments are to be included in the Ames Research Center (ARC) instrument compliments for the SW Pacific and Arctic ARM sites. Operational processing algorithms are in development for the data sets. The derived products are to be cloud presence and classification, base height, cirrus thickness, cirrus optical thickness, cirrus extinction profile, aerosol optical thickness and profile, and planetary boundary layer (PBL) height. A cloud presence and base height algorithm is in use, and a data set from the CART site is available. The scientific basis for the algorithm development of the higher level data products and plans for implementation are discussed.

  17. Dominance of organic aerosols in the marine boundary layer over the Gulf of Maine during NEAQS 2002 and their role in aerosol light scattering

    NASA Astrophysics Data System (ADS)

    Bates, T. S.; Quinn, P. K.; Coffman, D. J.; Johnson, J. E.; Middlebrook, A. M.

    2005-09-01

    Aerosol chemical, physical, and optical measurements were made aboard the NOAA R/V Ronald H. Brown off the coast of New England from July 12 through August 10, 2002, as part of the New England Air Quality Study (NEAQS). Measurements (generally 20 to 100 km from the coast) were made downwind of urban centers (New York City, Boston) and rural areas, and in air masses that had not been in contact with land for several days. On average during NEAQS, 75 ± 8% of the sub-10 μm aerodynamic diameter dry aerosol mass sampled 18 m above the sea surface was in the sub-1 μm fraction (size cut at 55% RH). The major submicrometer aerosol components were ammonium sulfate and particulate organic matter (POM, defined here as 1.6 times the mass concentration of organic carbon) comprising more than 92 ± 4% of the total mass. Under northwesterly flow with an average submicrometer total mass concentrations of 11 ± 4.5 μg m-3, POM was the dominant component (68 ± 8%) followed by (NH4)xHySO4 (23 ± 8%), inorganic oxidized material (IOM) (6 ± 4%), and EC (3 ± 1%). Under southwesterly flow with an average submicrometer total mass concentrations of 30 ± 11 μg m-3, (NH4)xHySO4 was the dominant component (54 ± 9%) followed by POM (41 ± 9%), IOM (3 ± 2%), and EC (2 ± 1%). Mie calculations using submicrometer nonrefractory (NR) POM and NR (NH4)xHySO4 + H2O size distributions to calculate submicrometer light scattering (σsp) at a wavelength of 550 nm suggest that POM was a dominant chemical component contributing to aerosol light scattering (haze) during NEAQS 2002, and contributed 60 ± 6 % and 57 ± 11 % to σsp at 55% RH during two pollution episodes off the New England Coast. These results are similar to those from the mid-Atlantic states during TARFOX but contrary to the long-term monitoring measurements over the continental northeast United States that show the New England haze is primarily a result of sulfate aerosol.

  18. Temporal and spectral cloud screening of polar winter aerosol optical depth (AOD): impact of homogeneous and inhomogeneous clouds and crystal layers on climatological-scale AODs

    NASA Astrophysics Data System (ADS)

    O'Neill, Norman T.; Baibakov, Konstantin; Hesaraki, Sareh; Ivanescu, Liviu; Martin, Randall V.; Perro, Chris; Chaubey, Jai P.; Herber, Andreas; Duck, Thomas J.

    2016-10-01

    We compared star-photometry-derived, polar winter aerosol optical depths (AODs), acquired at Eureka, Nunavut, Canada, and Ny-Ålesund, Svalbard, with GEOS-Chem (GC) simulations as well as ground-based lidar and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) retrievals over a sampling period of two polar winters. The results indicate significant cloud and/or low-altitude ice crystal (LIC) contamination which is only partially corrected using temporal cloud screening. Spatially homogeneous clouds and LICs that remain after temporal cloud screening represent an inevitable systematic error in the estimation of AOD: this error was estimated to vary from 78 to 210 % at Eureka and from 2 to 157 % at Ny-Ålesund. Lidar analysis indicated that LICs appeared to have a disproportionately large influence on the homogeneous coarse-mode optical depths that escape temporal cloud screening. In principle, spectral cloud screening (to yield fine-mode or submicron AODs) reduces pre-cloud-screened AODs to the aerosol contribution if one assumes that coarse-mode (super-micron) aerosols are a minor part of the AOD. Large, low-frequency differences between these retrieved values and their GC analogue appeared to be often linked to strong, spatially extensive planetary boundary layer events whose presence at either site was inferred from CALIOP profiles. These events were either not captured or significantly underestimated by the GC simulations. High-frequency AOD variations of GC fine-mode aerosols at Ny-Ålesund were attributed to sea salt, while low-frequency GC variations at Eureka and Ny-Ålesund were attributable to sulfates. CALIOP profiles and AODs were invaluable as spatial and temporal redundancy support (or, alternatively, as insightful points of contention) for star photometry retrievals and GC estimates of AOD.

  19. 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

  20. Scanning tropospheric ozone and aerosol lidar with double-gated photomultipliers.

    PubMed

    Machol, Janet L; Marchbanks, Richard D; Senff, Christoph J; McCarty, Brandi J; Eberhard, Wynn L; Brewer, William A; Richter, Ronald A; Alvarez, Raul J; Law, Daniel C; Weickmann, Ann M; Sandberg, Scott P

    2009-01-20

    The Ozone Profiling Atmospheric Lidar is a scanning four-wavelength ultraviolet differential absorption lidar that measures tropospheric ozone and aerosols. Derived profiles from the lidar data include ozone concentration, aerosol extinction, and calibrated aerosol backscatter. Aerosol calibrations assume a clear air region aloft. Other products include cloud base heights, aerosol layer heights, and scans of particulate plumes from aircraft. The aerosol data range from 280 m to 12 km with 5 m range resolution, while the ozone data ranges from 280 m to about 1.2 km with 100 m resolution. In horizontally homogeneous atmospheres, data from multiple-elevation angles is combined to reduce the minimum altitude of the aerosol and ozone profiles to about 20 m. The lidar design, the characterization of the photomultiplier tubes, ozone and aerosol analysis techniques, and sample data are described. Also discussed is a double-gating technique to shorten the gated turn-on time of the photomultiplier tubes, and thereby reduce the detection of background light and the outgoing laser pulse.

  1. Characterization of smoke aerosols over the Indochina Peninsula from multi-platform satellite observations

    NASA Astrophysics Data System (ADS)

    Jeong, M. J.; Hsu, N. Y. C.; Lee, J.; Sayer, A. M.; Bettenhausen, C.; Huang, J.

    2015-12-01

    Multi-faceted near-simultaneous observations from the sensors aboard multiple satellite platforms, so called the A-Train, are utilized to characterize the spatial distributions and the optical properties of smoke aerosols over the Indochina Peninsula. Observations from the A-Train sensors, especially, MODerate resolution Imaging Spectroradiometer (MODIS), Ozone Monitoring Instrument (OMI), and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), are synthesized to retrieve single-scattering albedo (SSA) and effective aerosol layer height (ALH) of BBS aerosols in the region. The retrieval algorithm extracts the absorption and height information about smoke aerosols, which is lumped into ultraviolet spectra at the top of the atmosphere, by taking the most reliable information contents that each satellite measurement can deliver. The results of retrieved SSA and ALH showed reasonable agreements with in-situ measurements, AEROsol Robotic NETwork (AERONET) data, and lidar-based observations. The uncertainty and sensitivity of the retrieval algorithm are also presented. The retrieved quantities are then used together with other satellite datasets to characterize the three-dimensional distributions of smoke aerosols over the Indochina Peninsular during the boreal spring time. Given the frequent horizontal collocations of smoke and clouds in the region, implication of smoke vertical distributions for long-range transports is also discussed. The results of this study are anticipated to advance our understanding on the climatic impacts of the smoke aerosols in the region.

  2. Scanning tropospheric ozone and aerosol lidar with double-gated photomultipliers.

    PubMed

    Machol, Janet L; Marchbanks, Richard D; Senff, Christoph J; McCarty, Brandi J; Eberhard, Wynn L; Brewer, William A; Richter, Ronald A; Alvarez, Raul J; Law, Daniel C; Weickmann, Ann M; Sandberg, Scott P

    2009-01-20

    The Ozone Profiling Atmospheric Lidar is a scanning four-wavelength ultraviolet differential absorption lidar that measures tropospheric ozone and aerosols. Derived profiles from the lidar data include ozone concentration, aerosol extinction, and calibrated aerosol backscatter. Aerosol calibrations assume a clear air region aloft. Other products include cloud base heights, aerosol layer heights, and scans of particulate plumes from aircraft. The aerosol data range from 280 m to 12 km with 5 m range resolution, while the ozone data ranges from 280 m to about 1.2 km with 100 m resolution. In horizontally homogeneous atmospheres, data from multiple-elevation angles is combined to reduce the minimum altitude of the aerosol and ozone profiles to about 20 m. The lidar design, the characterization of the photomultiplier tubes, ozone and aerosol analysis techniques, and sample data are described. Also discussed is a double-gating technique to shorten the gated turn-on time of the photomultiplier tubes, and thereby reduce the detection of background light and the outgoing laser pulse. PMID:19151820

  3. A Multi-Instrument Approach for Characterizing the Vertical Structure of Aerosol Properties: Case Studies in the Pacific Basin Troposphere

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Fenn, M. A.; Browell, E. V.; Grant, W. B.

    1998-01-01

    During February/March 1994, a series of aircraft-based aerosol measurements were carried out in the Pacific Basin troposphere using a differential absorption lidar system deployed by NASA Langley, and optical spectrometer probes and a wire-impactor system operated by NASA Ames. A modified Klett inversion algorithm was applied to extract altitude profiles of aerosol backscattering from the IR lidar signal. The algorithm that we have designed for this purpose utilizes the in situ aerosol measurements to normalize the lidar profile at the aircraft altitude and to supply the lidar ratio as a function of height. The lidar-derived aerosol backscattering coefficients were then compared to the backscattering coefficients calculated from the in situ measurements. During several local aircraft descents, we found good agreement between the remote lidar and in situ results for the absolute value of the aerosol backscattering coefficient and its altitude variation only when we allowed for several layers with different aerosol refractive indices. The agreement validates our lidar calibration method and provides an indication of the variation in aerosol refractive index as a function of altitude. Two of the three case studies performed in this paper reveal layers of anthropogenic aerosols transported long distances into the Pacific Basin troposphere. A third case implies the existence of a layer of dustlike aerosol particles in the lower troposphere, most likely of Asian origin.

  4. A multi-instrument approach for characterizing the vertical structure of aerosol properties: Case studies in the Pacific Basin troposphere

    NASA Astrophysics Data System (ADS)

    Redemann, J.; Turco, R. P.; Pueschel, R. F.; Fenn, M. A.; Browell, E. V.; Grant, W. B.

    1998-09-01

    During February/March 1994, a series of aircraft-based aerosol measurements were carried out in the Pacific Basin troposphere using a differential absorption lidar system deployed by NASA Langley, and optical spectrometer probes and a wire-impactor system operated by NASA Ames. A modified Klett inversion algorithm was applied to extract altitude profiles of aerosol backscattering from the IR lidar signal. The algorithm that we have designed for this purpose utilizes the in situ aerosol measurements to normalize the lidar profile at the aircraft altitude and to supply the lidar ratio as a function of height. The lidar-derived aerosol backscattering coefficients were then compared to the backscattering coefficients calculated from the in situ measurements. During several local aircraft descents, we found good agreement between the remote lidar and in situ results for the absolute value of the aerosol backscattering coefficient and its altitude variation only when we allowed for several layers with different aerosol refractive indices. The agreement validates our lidar calibration method and provides an indication of the variation in aerosol refractive index as a function of altitude. Two of the three case studies performed in this paper reveal layers of anthropogenic aerosols transported long distances into the Pacific Basin troposphere. A third case implies the existence of a layer of dustlike aerosol particles in the lower troposphere, most likely of Asian origin.

  5. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    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 pollution haze layer 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.

  6. 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.

  7. Multi-Sensor Estimation of Mixing Heights Over a Coastal City

    SciTech Connect

    Nielsen-Gammon, John W.; Powell, Christina L.; Mahoney, Michael J.; Angevine, Wayne M.; Senff, Christoph; White, Allen B.; Berkowitz, Carl M.; Doran, J. C.; Knupp, Kevin

    2008-01-01

    An airborne Microwave Temperature Profiler (MTP) was deployed during the An airborne Microwave Temperature Profiler (MTP) was deployed during the Texas 2000 Air Quality Study (TexAQS-2000) to make measurements of boundary layer thermal structure. An objective technique is developed and tested for estimating the mixed layer (ML) height from the MTP vertical temperature profiles. The technique identifies the ML height as a threshold increase of potential temperature from its minimum value within the boundary layer. In order to calibrate the technique and evaluate the usefulness of this approach, coincident estimates from radiosondes, radar wind profilers, an aerosol backscatter lidar, and in situ aircraft measurements were compared with each other and with the MTP. Relative biases among all instruments were generally less than 50 m, and the agreement between MTP ML height estimates and other estimates was at least as good as the agreement among the other estimates. The ML height estimates from the MTP and other instruments are utilized to determine the spatial and temporal evolution of ML height in the Houston area on 1 Sept. 2000. An elevated temperature inversion was present, so ML growth was inhibited until early afternoon. In the afternoon, large spatial variations in ML height developed across the Houston area. The highest ML heights, well over 2 km, were observed to the north of Houston, while downwind of Galveston Bay and within the late afternoon sea breeze ML heights were much lower. The spatial variations that were found away from the immediate influence of coastal circulations were unexpected, and multiple independent ML height estimates were essential for documenting this feature.

  8. Retrieval of effective complex refractive index from intensive measurements of characteristics of ambient aerosols in the boundary layer.

    PubMed

    Zhang, Xiaolin; Huang, Yinbo; Rao, Ruizhong; Wang, Zhien

    2013-07-29

    Aerosol complex refractive index (ACRI) has attracted intensive attentions due to its significance in modeling aerosol radiative effects. Determinations of ACRI from surface measurements of aerosol scattering and absorption coefficients as well as number size distributions during June, 2008 based on an iterative Mie algorithm were performed. The aim of our study was to introduce an inversion approach with the merits of high time-resolutions to retrieve the optically effective ACRI, especially its imaginary part. Based on simultaneous measurements of aerosol characteristics, mean ACRI value of 1.50 ( ± 0.34)-i0.025 ( ± 0.015) at 550 nm in Hefei in summer was deducted. The lower imaginary parts with higher single scattering albedos and lower scattering Angstrom exponents were obtained for haze periods compared with nonhaze conditions with similar air-mass back-trajectories, indicating more large and scattering particles contributing to the formation of haze episodes. The derived imaginary parts of ACRI related to agricultural biomass burning were in the range from 0.013 to 0.029 at 550 nm. Significant negative correlations between retrieved imaginary parts of ACRI and measured single scattering albedos indicate that our retrieval approach is a reasonable method for determining the imaginary parts of complex refractive indices of aerosol particles.

  9. 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

  10. Stratospheric aerosol increase after eruption of Pinatubo observed with lidar and aureolemeter

    NASA Technical Reports Server (NTRS)

    Hayashida, Sachiko; Sasano, Yasuhiro; Nakane, Hideaki; Matsui, Ichiro; Hayasaka, Tadahiro

    1994-01-01

    An increase in the amount of stratospheric aerosol due to the Pinatubo eruption (June 12-15, 1991, 15.14 deg N, 120.35 deg E) was observed from the end of June, 1991 by a lidar in NIES (National Institute for Environmental Studies), Tsukuba (36.0 deg N, 140.1 deg E). After large fluctuations in summer of 1991, the amount of the aerosols increased in mid-September as a result of enhanced transportation from the subtropical region. In autumn and winter of 1991, dense aerosol layers were continuously observed. Aureolemeter (scanning spectral radiometer) measurements were also carried out with lidar measurements and columnar size distribution of stratospheric aerosols was estimated for some cases. Collaborative measurements with the lidar and aureolemeter provided some information on height distribution of the surface area of aerosols in late 1991.

  11. Effect of temperature, atmospheric condition, and particle size on extinction in a plume of volatile aerosol dispersed in the atmospheric surface layer.

    PubMed

    Tsang, T T; Pai, P; Korgaonkar, N V

    1988-02-01

    The objective of this work is to study the effects of ambient temperature, atmospheric condition, and particle size on the extinction coefficient of diesel fuel and fog oil smoke. A first-order closure model is used to describe the turbulent diffusion of the smoke in the atmospheric surface layer. Mean values of wind speed and diffusivity in the vertical direction are obtained by the use of the Monin-Obukhov similarity theory. The 2-D crosswind line source model also includes the aerosol kinetic processes of evaporation, sedimentation, and deposition. Numerical results are obtained from simulations on a supercomputer.

  12. 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

  13. Aerosol vertical distribution, optical properties and transport over Corsica (western Mediterranean)

    NASA Astrophysics Data System (ADS)

    Léon, J.-F.; Augustin, P.; Mallet, M.; Bourrianne, T.; Pont, V.; Dulac, F.; Fourmentin, M.; Lambert, D.; Sauvage, B.

    2015-03-01

    This paper presents the aerosol vertical distribution observed in the western Mediterranean between February and April 2011 and between February 2012 and August 2013. An elastic backscattering lidar was continuously operated at a coastal site in the northern part of Corsica Island (Cap Corse) for a total of more than 14 000 h of observations. The aerosol extinction coefficient retrieved from cloud-free lidar profiles are analyzed along with the SEVIRI satellite aerosol optical depth (AOD). The SEVIRI AOD was used to constrain the retrieval of the aerosol extinction profiles from the lidar range-corrected signal and to detect the presence of dust or pollution aerosols. The daily average AOD at 550 nm is 0.16 (±0.09) and ranges between 0.05 and 0.80. A seasonal cycle is observed with minima in winter and maxima in spring-summer. High AOD days (above 0.3 at 550 nm) represent less than 10% of the totality of daily observations and correspond to the large scale advection of desert dust from Northern Africa or pollution aerosols from Europe. The respective origin of the air masses is confirmed using FLEXPART simulations in the backward mode. Dust events are characterized by a large turbid layer between 2 and 5 km height while pollution events show a lower vertical development with a thick layer below 3 km in altitude. However low level dust transport is also reported during spring while aerosol pollution layer between 2 and 4 km height has been also observed. We report an effective lidar ratio at 355 nm for pollution aerosols 68 (±13) Sr while it is 63 (±18) Sr for dust. The daily mean AOD at 355 nm for dust events is 0.61 (±0.14) and 0.71 (±0.16) for pollution aerosols events.

  14. Three-dimensional structure of aerosol in China: A perspective from multi-satellite observations

    NASA Astrophysics Data System (ADS)

    Guo, Jianping; Liu, Huan; Wang, Fu; Huang, Jingfeng; Xia, Feng; Lou, Mengyun; Wu, Yerong; Jiang, Jonathan H.; Xie, Tao; Zhaxi, Yangzong; Yung, Yuk L.

    2016-09-01

    Using eight years (2006-2014) of passive (MODIS/Aqua and OMI/Aura) and active (CALIOP/CALIPSO) satellite measurements of aerosols, we yield a three-dimensional (3D) distribution of the frequency of occurrence (FoO) of aerosols over China. As an indicator of the vertical heterogeneity of aerosol layers detected by CALIOP, two types of Most Probable Height (MPH), including MPH_FoO and MPH_AOD, are deduced. The FoO of "Total Aerosol" reveals significant geographical dependence. Eastern China showed much stronger aerosol FoD than northwestern China. The FoO vertical structures of aerosol layer are strongly dependent on altitudes. Among the eight typical ROIs analyzed, aerosol layers over the Gobi Desert have the largest occurrence probability located at an altitude as high as 2.83 km, as compared to 1.26 km over Beijing-Tianjin-Hebei. The diurnal variation (nighttime-daytime) in MPH_AOD varies from an altitude as low as 0.07 km over the Sichuan basin to 0.27 km over the Gobi Desert, whereas the magnitude of the diurnal variation in terms of MPH_AOD is six times as large as the MPH_FoO, mostly attributable to the day/night lidar SNR difference. Also, the 3D distribution of dust and smoke aerosols was presented. The multi-sensor synergized 3D observations of dust aerosols, frequently observed in the zonal belt of 38°N-45°N, is markedly different from that of smoke aerosols that are predominantly located in the eastern and southern parts. The 3D FoO distribution of dust indicates a west-to-east passageway of dust originating from the westernmost Taklimakan Desert all the way to North China Plain (NCP). The findings from the multi-sensor synergetic observations greatly improved our understanding on the long-range aerosol dispersion, transport and passageway over China.

  15. 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.

  16. Corona-like atmospheric escape from KBOs. II. The behavior of aerosols

    NASA Astrophysics Data System (ADS)

    Levi, Amit; Podolak, Morris

    2009-10-01

    In Levi and Podolak (Levi, A., Podolak, M. [in press] Icarus) we applied the theory of coronal expansion to gas escape from a small, cold, object such as those found in the Kuiper belt. Here we extend the theory to include aerosols that are lifted off the surface by the escaping gas. Aerosols carried by the gas but still gravitationally bound, tend to be lifted to a height above the surface that is dependent on the aerosol radius, so that in steady state the variation of aerosol radius with height is well-defined. We develop an extension of Parker's coronal flow theory to include the effect of aerosols carried along by the gas and use this to estimate the optical depth of such an atmosphere. For KBOs with CO evaporation from the surface and with radii in the range 245-334 km, line-of-site optical depths through the atmosphere can exceed one at heights of a few hundred kilometers above the surface. Such aerosol layers should be observable, and might be used to infer the flow proprieties of the escaping gas.

  17. 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

  18. Radiative effects of African dust and smoke observed from Clouds and the Earth's Radiant Energy System (CERES) and Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data

    NASA Astrophysics Data System (ADS)

    Yorks, John E.; McGill, Matt; Rodier, Sharon; Vaughan, Mark; Hu, Yongxiang; Hlavka, Dennis

    2009-09-01

    Cloud and aerosol effects have a significant impact on the atmospheric radiation budget in the tropical Atlantic because of the spatial and temporal extent of desert dust and smoke from biomass burning in the atmosphere. The influences of African dust and smoke aerosols on cloud radiative properties over the tropical Atlantic Ocean were analyzed for the month of July for 3 years (2006-2008) using colocated data collected by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) and Clouds and the Earth's Radiant Energy System (CERES) instruments on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) and Aqua satellites. Aerosol layer height and type can be accurately determined using CALIOP data through directly measured parameters such as optical depth, volume depolarization ratio, attenuated backscatter, and color ratio. On average, clouds below 5 km had a daytime instantaneous shortwave (SW) radiative flux of 270.2 ± 16.9 W/m2 and thin cirrus clouds had a SW radiative flux of 208.0 ± 12.7 W/m2. When dust aerosols interacted with clouds below 5 km, as determined from CALIPSO, the SW radiative flux decreased to 205.4 ± 13.0 W/m2. Similarly, smoke aerosols decreased the SW radiative flux of low clouds to a value of 240.0 ± 16.6 W/m2. These decreases in SW radiative flux were likely attributed to the aerosol layer height and changes in cloud microphysics. CALIOP lidar observations, which more accurately identify aerosol layer height than passive instruments, appear essential for better understanding of cloud-aerosol interactions, a major uncertainty in predicting the climate system.

  19. Observations of the Interaction and/or Transport of Aerosols with Cloud or Fog during DRAGON Campaigns from AERONET Ground-Based Remote Sensing

    NASA Astrophysics Data System (ADS)

    Eck, Thomas; Holben, Brent; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Reid, Jeffrey; Pickering, Kenneth; Crawford, James; Sinyuk, Alexander; Trevino, Nathan

    2014-05-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Recent major DRAGON field campaigns in Japan and South Korea (Spring 2012) and California (Winter 2013) have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth signal for these cases of persistent and extensive cloud cover. Additionally, extensive fog that was coincident with aerosol layer height on some days in both Korea and California resulted in large increases in fine mode aerosol radius, with a mode of cloud-processed or residual aerosol of radius ~0.4-0.5 micron sometimes observed. Cloud processed aerosol may occur much more frequently than AERONET data suggest due to inherent difficulty in observing aerosol properties near clouds from remote sensing observations. These biases of aerosols associated with clouds would likely be even greater for satellite remote sensing retrievals of aerosol properties near clouds due to 3-D effects and sub-pixel cloud contamination issues.

  20. Schottky barrier height reduction for metal/n-InP by inserting ultra-thin atomic layer deposited high-k dielectrics

    SciTech Connect

    Zheng, Shan; Yang, Wen; Sun, Qing-Qing E-mail: linchen@fudan.edu.cn; Zhou, Peng; Wang, Peng-Fei; Wei Zhang, David; Chen, Lin; Xiao, Fei

    2013-12-23

    Fermi level pinning at metal/n-InP interface and effective Schottky barrier height (Φ{sub B,eff}) were optimized by inserting ultrathin dielectrics in this work. Comparing the inserted monolayer and bilayer high-k dielectrics, we demonstrated that the introduction of bilayer dielectrics can further reduce Φ{sub B,eff} (from 0.49 eV to 0.22 eV) than the monolayer dielectric (from 0.49 eV to 0.32 eV) even though the overall dielectric thickness was thicker. The additional dipole formed at high-k/high-k interfaces could be used to expound the mechanism. This work proposed an effective solution to reduce resistance contacts for InP based transistors and Schottky barrier transistors.

  1. Contribution of dissolved organic matter to submicron water-soluble organic aerosols in the marine boundary layer over the eastern equatorial Pacific

    NASA Astrophysics Data System (ADS)

    Miyazaki, Yuzo; Coburn, Sean; Ono, Kaori; Ho, David T.; Pierce, R. Bradley; Kawamura, Kimitaka; Volkamer, Rainer

    2016-06-01

    Stable carbon isotopic compositions of water-soluble organic carbon (WSOC) and organic molecular markers were measured to investigate the relative contributions of the sea surface sources to the water-soluble fraction of submicron organic aerosols collected over the eastern equatorial Pacific during the Tropical Ocean tRoposphere Exchange of Reactive halogens and Oxygenated VOCs (TORERO)/KA-12-01 cruise. On average, the water-soluble organic fraction of the total carbon (TC) mass in submicron aerosols was ˜ 30-35 % in the oceans with the low chlorophyll a (Chl a) concentrations, whereas it was ˜ 60 % in the high-Chl a regions. The average stable carbon isotope ratio of WSOC (δ13CWSOC) was -19.8 ± 2.0 ‰, which was systematically higher than that of TC (δ13CTC) (-21.8 ± 1.4 ‰). We found that in the oceans with both high and low Chl a concentrations the δ13CWSOC was close to the typical values of δ13C for dissolved organic carbon (DOC), ranging from -22 to -20 ‰ in surface seawater of the tropical Pacific Ocean. This suggests an enrichment of marine biological products in WSOC aerosols in the study region regardless of the oceanic area. In particular, enhanced levels of WSOC and biogenic organic marker compounds together with high values of WSOC / TC ( ˜ 60 %) and δ13CWSOC were observed over upwelling areas and phytoplankton blooms, which was attributed to planktonic tissues being more enriched in δ13C. The δ13C analysis estimated that, on average, marine sources contribute ˜ 90 ± 25 % of the aerosol carbon, indicating the predominance of marine-derived carbon in the submicron WSOC. This conclusion is supported by Lagrangian trajectory analysis, which suggests that the majority of the sampling points on the ship had been exposed to marine boundary layer (MBL) air for more than 80 % of the time during the previous 7 days. The combined analysis of the δ13C and monosaccharides, such as glucose and fructose, demonstrated that DOC concentration was

  2. Variability of CCN Activation Behaviour of Aerosol Particles in the Marine Boundary Layer of the Northern and Southern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Henning, Silvia; Dieckmann, Katrin; Hartmann, Susan; Schäfer, Michael; Wu, Zhijun; Merkel, Maik; Wiedensohler, Alfred; Stratmann, Frank

    2013-04-01

    The variability of cloud condensation nucleus (CCN) activation behaviour and total CCN number concentrations was investigated during three ship cruises. Measurements were performed in a mobile laboratory on the German research vessel FS Polarstern cruising between Cape Town and Bremerhaven (April / May and October / November 2011) as well as between Punta Arenas and Bremerhaven (April / May 2012). CCN size distributions were measured for supersaturations between 0.1% and 0.4% using a Cloud Condensation Nucleus Counter (DMT, USA). Aerosol particle and CCN total number concentrations as well as the hygroscopicity parameter κ (Petters and Kreidenweis, 2007) were determined. Furthermore, size distribution data were collected. The hygroscopicity parameter κ featured a high variability during the cruises, with a median κ-value of 0.52 ± 0.26. The κ-values are depended on air mass origin; and are as expected mainly dominated by marine influences, but also long range transport of aerosol particles was detected. In the Celtic Sea, κ was found to be lower than that of clean marine aerosol particles (0.72 ± 0.24; Pringle et al., 2010) with κ-values ~0.2, possibly influenced by anthropogenic emissions from Europe. Close to the West African coast particle hygroscopicity was found to be influenced by the Saharan dust plume, resulting in low κ-values ~0.25. Petters, M.D. and S.M. Kreidenweis (2007), A single parameter representation of hygroscopic growth and cloud condensation nucleus activity, Atmos. Chem. and Phys., 7, 1961-1971. Pringle, K.J., H. Tost, A. Pozzer, U. Pöschl, and J. Lelieveld (2010), Global distribution of the effective aerosol hygroscopicity parameter for CCN activation, Atmos. Chem. Phys., 10, 5241-5255.

  3. Mass-analysis of Charged Aerosol Particles in a PMSE/NLC Layer by a Rocket-borne Spectrometer

    NASA Astrophysics Data System (ADS)

    Robertson, Scott; Knappmiller, Scott; Horanyi, Mihaly; Sternovsky, Zoltan; Baumgarten, Gerd; Latteck, Ralph; Rapp, Markus; Holzworth, Robert; Shimogawa, Michael; Gumbel, Jorg; Megner, Ms Linda; Friedrich, Martin

    Two "MASS" rockets (Mesospheric Aerosol Sampling Spectrometer) were launched from the Andoya Rocket Range (Norway) the first week of August 2007. The payloads carried an electrostatic mass analyzer for the charged fraction of the aerosol particles, electric field booms, a photometer for cloud brightness, and Faraday rotation antennas for electron density. Aerosol particles with different ranges of charge-to-mass ratio were collected within the instrument housing on two sets of four biased collector plates, with one set for positive particles and one set for negative particles. The first rocket was launched into PMSE and NLC on 3 August. The sun was 4 degrees below the horizon and NLC were seen in the previous hour at 83 km by the ALOMAR RMR lidar. NLC were detected at the same altitude by rocket-borne photometer measurements. The charged aerosol data shows the density of negative particles with radius greater than 3 nm rising sharply at 83 km and continuing to 89 km, collocated with PMSE detected by the ALWIN radar. Particles with 1-2 nm radii with both signs of charge and particles with less than 1 nm radius charged positively were detected at 86-88 km. The occurrence of the positive particles in the smallest size range in the region of lowest temperature suggests that their origin is nucleation and growth on ions. Initial charge-density estimates are several thousands per cubic centimeter for each of these size ranges. The second launch was 6 August into PMSE without NLC. The 1-2 nm particles were seen from 85.4 to 87.4 km, again with both signs of charge. Larger sizes were nearly absent.

  4. Ice nucleating particles at a coastal marine boundary layer site: correlations with aerosol type and meteorological conditions

    NASA Astrophysics Data System (ADS)

    Mason, R. H.; Si, M.; Li, J.; Chou, C.; Dickie, R.; Toom-Sauntry, D.; Pöhlker, C.; Yakobi-Hancock, J. D.; Ladino, L. A.; Jones, K.; Leaitch, W. R.; Schiller, C. L.; Abbatt, J. P. D.; Huffman, J. A.; Bertram, A. K.

    2015-11-01

    Information on what aerosol particle types are the major sources of ice nucleating particles (INPs) in the atmosphere is needed for climate predictions. To determine which aerosol particles are the major sources of immersion-mode INPs at a coastal site in Western Canada, we investigated correlations between INP number concentrations and both concentrations of different atmospheric particles and meteorological conditions. We show that INP number concentrations are strongly correlated with the number concentrations of fluorescent bioparticles between -15 and -25 °C, and that the size distribution of INPs is most consistent with the size distribution of fluorescent bioparticles. We conclude that biological particles were likely the major source of ice nuclei at freezing temperatures between -15 and -25 °C at this site for the time period studied. At -30 °C, INP number concentrations are also well correlated with number concentrations of the total aerosol particles ≥ 0.5 μm, suggesting that non-biological particles may have an important contribution to the population of INPs active at this temperature. As we found that black carbon particles were unlikely to be a major source of ice nuclei during this study, these non-biological INPs may include mineral dust. Furthermore, correlations involving chemical tracers of marine aerosols and marine biological activity, sodium and methanesulfonic acid, indicate that the majority of INPs measured at the coastal site likely originated from terrestrial rather than marine sources. Finally, six existing empirical parameterizations of ice nucleation were tested to determine if they accurately predict the measured INP number concentrations. We found that none of the parameterizations selected are capable of predicting INP number concentrations with high accuracy over the entire temperature range investigated. This finding illustrates that additional measurements are needed to improve parameterizations of INPs and their

  5. Activation of the Solid Silica Layer of Aerosol-Based C/SiO₂ Particles for Preparation of Various Functional Multishelled Hollow Microspheres.

    PubMed

    Li, Xiangcun; Luo, Fan; He, Gaohong

    2015-05-12

    Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

  6. LOSA-M2 aerosol Raman lidar

    SciTech Connect

    Balin, Yu S; Bairashin, G S; Kokhanenko, G P; Penner, I E; Samoilova, S V

    2011-10-31

    The scanning LOSA-M2 aerosol Raman lidar, which is aimed at probing atmosphere at wavelengths of 532 and 1064 nm, is described. The backscattered light is received simultaneously in two regimes: analogue and photon-counting. Along with the signals of elastic light scattering at the initial wavelengths, a 607-nm Raman signal from molecular nitrogen is also recorded. It is shown that the height range of atmosphere probing can be expanded from the near-Earth layer to stratosphere using two (near- and far-field) receiving telescopes, and analogue and photon-counting lidar signals can be combined into one signal. Examples of natural measurements of aerosol stratification in atmosphere along vertical and horizontal paths during the expeditions to the Gobi Desert (Mongolia) and Lake Baikal areas are presented.

  7. Airborne High Spectral Resolution Lidar Measurements of Aerosol Distributions and Properties during the NASA DISCOVER-AQ Missions

    NASA Astrophysics Data System (ADS)

    Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Scarino, A. J.; Burton, S. P.; Harper, D. B.; Cook, A. L.; Berkoff, T.; Rogers, R. R.; Seaman, S. T.; Fenn, M. A.; Sawamura, P.; Clayton, M.; Mueller, D.; Chemyakin, E.; Anderson, B. E.; Beyersdorf, A. J.; Ziemba, L. D.; Crawford, J. H.

    2015-12-01

    The NASA Langley Research Center airborne High Spectral Resolution Lidars, HSRL-1 and HSRL-2, were deployed for the DISCOVER-AQ (Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality) missions. DISCOVER-AQ provided systematic and concurrent observations of column-integrated, surface, and vertically-resolved distributions of aerosols and trace gases to improve the interpretation of satellite observations related to air quality. HSRL-1, deployed during the first DISCOVER-AQ mission over the Washington DC-Baltimore region, measured profiles of aerosol backscatter and depolarization (532, 1064 nm) and aerosol extinction and optical thickness (AOT) (532 nm). HSRL-2, the first airborne multiwavelength HSRL, was deployed for the following three DISCOVER-AQ missions over the California Central Valley, Houston, and Denver. HSRL-2 measures profiles of aerosol backscatter and depolarization (355, 532, 1064 nm) and aerosol extinction and AOT (355, 532 nm). Additional HSRL-2 data products include aerosol type, mixed layer depth, and range-resolved aerosol microphysical parameters. The HSRL measurements reveal the temporal, spatial, and vertical variability of aerosol optical properties over these locations. HSRL measurements show that surface PM2.5 concentrations were better correlated with near surface aerosol extinction than AOT scaled by the mixed layer height. During the missions over Washington DC-Baltimore, Houston, and Denver, only about 20-65% of AOT was within the mixed layer. In contrast, nearly all of the AOT was within the mixed layer over the California Central Valley. HSRL-2 retrievals of aerosol fine mode volume concentration and effective radius compare well with coincident airborne in situ measurements and vary with relative humidity. HSRL-2 retrievals of aerosol fine mode volume concentration were also used to derive PM2.5 concentrations which compare well with surface PM2.5 measurements.

  8. Estimation of global anthropogenic dust aerosol using CALIOP satellite

    NASA Astrophysics Data System (ADS)

    Chen, B.; Huang, J.; Liu, J.

    2014-12-01

    Anthropogenic dust aerosols are those produced by human activity, which mainly come from cropland, pasture, and urban in this paper. Because understanding of the emissions of anthropogenic dust is still very limited, a new technique for separating anthropogenic dust from natural dustusing CALIPSO dust and planetary boundary layer height retrievalsalong with a land use dataset is introduced. Using this technique, the global distribution of dust is analyzed and the relative contribution of anthropogenic and natural dust sources to regional and global emissions are estimated. Local anthropogenic dust aerosol due to human activity, such as agriculture, industrial activity, transportation, and overgrazing, accounts for about 22.3% of the global continentaldust load. Of these anthropogenic dust aerosols, more than 52.5% come from semi-arid and semi-wet regions. On the whole, anthropogenic dust emissions from East China and India are higher than other regions.

  9. The combined effects of electrojet strength and the geomagnetic activity (Kp-index) on the post sunset height rise of the F-layer and its role in the generation of ESF during high and low solar activity periods

    NASA Astrophysics Data System (ADS)

    Tulasi Ram, S.; Rama Rao, P. V. S.; Prasad, D. S. V. V. D.; Niranjan, K.; Raja Babu, A.; Sridharan, R.; Devasia, C. V.; Ravindran, Sudha

    2007-10-01

    Several investigations have been carried out to identify the factors that are responsible for the day-to-day variability in the occurrence of equatorial spread-F (ESF). But the precise forecasting of ESF on a day-to-day basis is still far from reality. The nonlinear development and the sustenance of ESF/plasma bubbles is decided by the background ionospheric conditions, such as the base height of the F-layer (h'F), the electron density gradient (dN/dz), maximum ionization density (Nmax), geomagnetic activity and the neutral dynamics. There is increasing evidence in the literature during the recent past that shows a well developed Equatorial Ionization Anomaly (EIA) during the afternoon hours contributes significantly to the initiation of ESF during the post-sunset hours. Also, there exists a good correlation between the Equatorial Ionization Anomaly (EIA) and the Integrated Equatorial ElectroJet (IEEJ) strength, as the driving force for both is the same, namely, the zonal electric field at the equator. In this paper, we present a linear relationship that exists between the daytime integrated equatorial electrojet (IEEJ) strength and the maximum elevated height of the F-layer during post-sunset hours (denoted as peak h'F). An inverse relationship that exists between the 6-h average Kp-index prior to the local sunset and the peak h'F of the F-layer is also presented. A systematic study on the combined effects of the IEEJ and the average Kp-index on the post-sunset, peak height of the F-layer (peak h'F), which controls the development of ESF/plasma bubbles, is carried out using the ionosonde data from an equatorial station, Trivandrum (8.47° N, 76.91° E, dip.lat. 0.5° N), an off-equatorial station, SHAR (13.6° N, 79.8° E, dip.lat. 10.8° N) and VHF scintillations (244 MHz) observed over a nearby low-latitude station, Waltair (17.7° N, 83.3° E, dip.lat. 20° N). From this study, it has been found that the threshold base height of the F-layer at the equator for

  10. Use of Lidar Derived Optical Extinction and Backscattering Coefficients Near Cloud Base to Explore Aerosol-Cloud Interactions

    NASA Astrophysics Data System (ADS)

    Han, Zaw; Wu, Yonhgua; Gross, Barry; Moshary, Fred

    2016-06-01

    Combination of microwave radiometer (MWR) and mutlifilter rotating shadowband radiometer (MFRSR) measurement data together with SBDART radiative transfer model to compute cloud optical depth (COD) and cloud droplet effective radius (Reff). Quantify the first aerosol indirect effect using calculated Reff and aerosol extinction from Raman lidar measurement in urban coastal region. Illustrate comparison between ground-based and satellite retrievals. Demonstrate relationship between surface aerosol (PM2.5) loading and Reff. We also explain the sensitivity of aerosol-cloud-index (ACI) depend on the aerosol layer from cloud base height. Potential used of less noisy elastic backscattering to calculate the ACI instead of using Raman extinction. We also present comparison of elastic backscattering and Raman extinction correlation to Reff.

  11. Analysis of the origin of peak aerosol optical depth in springtime over the Gulf of Tonkin.

    PubMed

    Shan, Xiaoli; Xu, Jun; Li, Yixue; Han, Feng; Du, Xiaohui; Mao, Jingying; Chen, Yunbo; He, Youjiang; Meng, Fan; Dai, Xuezhi

    2016-02-01

    By aggregating MODIS (moderate-resolution imaging spectroradiometer) AOD (aerosol optical depth) and OMI (ozone monitoring instrument) UVAI (ultra violet aerosol index) datasets over 2010-2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin (17-23 °N, 105-110 °E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP (cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km. In contrast, aerosol loading in the low atmosphere (below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula (NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring. PMID:26969552

  12. Analysis of the origin of peak aerosol optical depth in springtime over the Gulf of Tonkin.

    PubMed

    Shan, Xiaoli; Xu, Jun; Li, Yixue; Han, Feng; Du, Xiaohui; Mao, Jingying; Chen, Yunbo; He, Youjiang; Meng, Fan; Dai, Xuezhi

    2016-02-01

    By aggregating MODIS (moderate-resolution imaging spectroradiometer) AOD (aerosol optical depth) and OMI (ozone monitoring instrument) UVAI (ultra violet aerosol index) datasets over 2010-2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin (17-23 °N, 105-110 °E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP (cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km. In contrast, aerosol loading in the low atmosphere (below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula (NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring.

  13. Stereoscopic Retrieval of Smoke Plume Heights and Motion from Space-Based Multi-Angle Imaging, Using the MISR INteractive eXplorer(MINX)

    NASA Technical Reports Server (NTRS)

    Nelson, David L.; Kahn, Ralph A.

    2014-01-01

    Airborne particles desert dust, wildfire smoke, volcanic effluent, urban pollution affect Earth's climate as well as air quality and health. They are found in the atmosphere all over the planet, but vary immensely in amount and properties with season and location. Most aerosol particles are injected into the near-surface boundary layer, but some, especially wildfire smoke, desert dust and volcanic ash, can be injected higher into the atmosphere, where they can stay aloft longer, travel farther, produce larger climate effects, and possibly affect human and ecosystem health far downwind. So monitoring aerosol injection height globally can make important contributions to climate science and air quality studies. The Multi-angle Imaging Spectro-Radiometer (MISR) is a space borne instrument designed to study Earths clouds, aerosols, and surface. Since late February 2000 it has been retrieving aerosol particle amount and properties, as well as cloud height and wind data, globally, about once per week. The MINX visualization and analysis tool complements the operational MISR data products, enabling users to retrieve heights and winds locally for detailed studies of smoke plumes, at higher spatial resolution and with greater precision than the operational product and other space-based, passive remote sensing techniques. MINX software is being used to provide plume height statistics for climatological studies as well as to investigate the dynamics of individual plumes, and to provide parameterizations for climate modeling.

  14. Speciation of water-soluble organic carbon compounds in boundary layer aerosols during the LBA/CLAIRE/SMOCC-2002 campaign

    NASA Astrophysics Data System (ADS)

    Claeys, M.; Pashynska, V.; Vermeylen, R.; Vas, G.; Cafmeyer, J.; Maenhaut, W.; Artaxo, P.

    2003-04-01

    The water-soluble, hygroscopic aerosol fraction is of climatic interest because of its role as cloud condensation nuclei (CCN) and the associated effects on cloud formation and cloud properties. As part of the LBA/CLAIRE/SMOCC experiment in Amazonia, September-November 2002, aerosol samples were collected using various types of samplers. The campaign spanned from the peak of the burning season, with high smoke concentrations, to fairly clean conditions in the early rainy season. Separate day and night samples were collected, and the collection time per sample varied from 12 hours in September to up to 48 hours in November. Fine (< 2.5 μm) and coarse (> 2.5 μm) aerosol size fractions were obtained using a Hi-Vol dichotomous sampler, and the samples were analysed for organic carbon (OC), elemental carbon (EC), water-soluble organic carbon (WSOC) and various water-soluble organic carbon compounds. The latter compounds included the anhydrosugars, levoglucosan, mannosan, and galactosan, which are markers for wood combustion, the polyols, arabitol and mannitol, which originate from the natural forest environment, as well as the hydroxydicarboxylic acid, malic acid, which is a late product in the photochemistry of fatty acids and n-alkanes. Preliminary results including the mass concentrations of OC, EC, WSOC and the water-soluble organic compounds will be presented. By far the major water-soluble organic carbon compound in the fine size fraction was levoglucosan, showing concentrations in the range of 1-6 μg m-3 in the peak of the burning season (17-24 September).

  15. Cloud Coverage and Height Distribution from the GLAS Polar Orbiting Lidar: Comparison to Passive Cloud Retrievals

    NASA Technical Reports Server (NTRS)

    Spinhime, J. D.; Palm, S. P.; Hlavka, D. L.; Hart, W. D.; Mahesh, A.

    2004-01-01

    The Geoscience Laser Altimeter System (GLAS) began full on orbit operations in September 2003. A main application of the two-wavelength GLAS lidar is highly accurate detection and profiling of global cloud cover. Initial analysis indicates that cloud and aerosol layers are consistently detected on a global basis to cross-sections down to 10(exp -6) per meter. Images of the lidar data dramatically and accurately show the vertical structure of cloud and aerosol to the limit of signal attenuation. The GLAS lidar has made the most accurate measurement of global cloud coverage and height to date. In addition to the calibrated lidar signal, GLAS data products include multi level boundaries and optical depth of all transmissive layers. Processing includes a multi-variable separation of cloud and aerosol layers. An initial application of the data results is to compare monthly cloud means from several months of GLAS observations in 2003 to existing cloud climatologies from other satellite measurement. In some cases direct comparison to passive cloud retrievals is possible. A limitation of the lidar measurements is nadir only sampling. However monthly means exhibit reasonably good global statistics and coverage results, at other than polar regions, compare well with other measurements but show significant differences in height distribution. For polar regions where passive cloud retrievals are problematic and where orbit track density is greatest, the GLAS results are particularly an advance in cloud cover information. Direct comparison to MODIS retrievals show a better than 90% agreement in cloud detection for daytime, but less than 60% at night. Height retrievals are in much less agreement. GLAS is a part of the NASA EOS project and data products are thus openly available to the science community (see http://glo.gsfc.nasa.gov).

  16. Global profiles of the direct aerosol effect using vertically resolved aerosol data

    NASA Astrophysics Data System (ADS)

    Korras Carraca, Marios Bruno; Pappas, Vasilios; Matsoukas, Christos; Hatzianastassiou, Nikolaos; Vardavas, Ilias

    2014-05-01

    vertical layers from the ground level up to 50 mb. This is the first study to our knowledge that provides vertically resolved all-sky DRE globally. We find that the columnar global average value of the CALIOP optical depth at 500 nm is 0.0815. The DRE at the surface is -3.14 Wm-2 (net) and -3.82 Wm-2 (downwelling), at the top of the atmosphere it is -1.21 Wm-2, and in the atmosphere 1.94 Wm-2. As expected however, very large local and seasonal differences from these values are found if one focuses on specific locations and months. Preliminary results show that that there are notable differences in the DRE produced by our radiation transfer model with vertically resolved aerosol profiles compared with columnar values over some cloudy areas, depending on the aerosol height relatively to the clouds. We examine more closely the interplay of radiation fluxes between aerosol and clouds for a few interesting cases.

  17. A Parameterization of Wildfire Emission Injection Heights in North America: Analysis from Satellite Observations and Models

    NASA Astrophysics Data System (ADS)

    Val Martin, M.; Logan, J. A.; Kahn, R. A.; Ichoku, C. M.; Freitas, S. R.; Cantin, A.

    2009-12-01

    Fire emissions can be injected above the boundary layer due to strong buoyancy generated from the fires, with important implications for long-range transport of these emissions and their effects on atmospheric composition. A multi-year record of aerosol smoke plume heights derived from observations made by the NASA Terra Multi-angle Imaging SpectroRadiometer (MISR) shows that fire smoke injection heights in the North American biomes are highly variable, ranging from a few hundred meters to 5000 m above the terrain, at the Terra overpass time. The analysis of plume heights with assimilated meteorological observations from the NASA Goddard Earth Observing System and measurements of the MODerate resolution Imaging Spectroradiometer (MODIS) fire radiative power (FRP) indicates the important effect of both buoyancy generated by the fires and local atmospheric structure on the ultimate rise of these fire emissions. Here, we evaluate a 1-D plume-rise model, driven by MODIS-based fire properties and local meteorology, using the MISR smoke plume height dataset as a constraint. We also use the 1-D plume-rise model to investigate the effect of the diurnal variation of these physical processes on the injection heights. A non-computationally expensive parametrization of fire emission injection heights over North America for chemical transport models is discussed, and preliminary results using the 3-D global chemistry transport model GEOS-Chem during the ARCTAS campaign are presented.

  18. Comparison of Aerosol Properties Within and Above the ABL at the ARM Program's SGP Site

    SciTech Connect

    Delle Monache, L

    2002-05-01

    The goal of this thesis is to determine under what conditions, if any, measurements of aerosol properties made at the Earth's surface are representative of aerosol properties within the column of air above the surface. This thesis will use data from the Atmospheric Radiation Measurement (ARM) site at the Southern Great Plains (SGP) which is the only location in the world where ground-based and in situ airborne measurements are made on a routine basis. All flight legs in the one-year period from March 2000-March 2001 were categorized as either within or above the atmospheric boundary layer using an objective mixing height determination technique. The correlations between the aerosol properties measured at the surface and the measured within and above the ABL were then computed. The conclusion of this comparison is that the aerosol extensive and intensive properties measured at the surface are representative of values within the ABL, but not within the free atmosphere.

  19. Modeling of microphysics and optics of aerosol particles in the marine environments

    NASA Astrophysics Data System (ADS)

    Kaloshin, Gennady

    2013-05-01

    We present a microphysical model for the surface layer marine and coastal atmospheric aerosols that is based on long-term observations of size distributions for 0.01-100 μm particles. The fundamental feature of the model is a parameterization of amplitudes and widths for aerosol modes of the aerosol size distribution function (ASDF) as functions of fetch and wind speed. The shape of ASDF and its dependence on meteorological parameters, height above sea level (H), fetch (X), wind speed (U) and relative humidity (RH), are investigated. At present, the model covers the ranges H = 0 - 25 m, U = 3 - 18 km s-1, X ≤ 120 km and RH = 40 - 98%. The latest version of the Marine Aerosol Extinction Profiles model (MaexPro) is described and applied for the computation and analysis of the spectral profiles of aerosol extinction coefficients α(λ) in the wavelength band λ = 0.2-12 μm. MaexPro is based on the aforementioned aerosol model assuming spherically shaped aerosol particles and the well-known Mie theory. The spectral profiles of α(λ) calculated by MaexPro are in good agreement with observational data and the numerical results. Moreover, MaexPro was found to be an accurate and reliable tool for investigating the optical properties of atmospheric aerosols.

  20. Continuous and automatic measurement of atmospheric structures and aerosols optical properties with R-Man510 nitrogen Raman lidar

    NASA Astrophysics Data System (ADS)

    Royer, P.; Renaudier, M.; Sauvage, L.; Boquet, M.; Thobois, L.; Bizard, A.

    2012-04-01

    A new compact and light nitrogen Raman lidar (R-Man510) has recently been developed by Leosphere company. This UV-lidar system is based on a low energy diode pumped Nd:YAG laser at 355 nm and has been developed to be operated unmanly for the meteorological and airport needs. Measurements are typically performed with a vertical resolution between 15 and 60 m and a temporal resolution between 30 seconds (for elastic channel) and 10 minutes (for Raman channel). The elastic channel of the lidar is used to automatically detect up to 9 atmospheric structures (Plantery Boundary Layer height, aerosol and cloud layers) in quasi real-time. Aerosols are classified in 6 types (pollution aerosols, desert dusts, volcanic ashes, marine aerosols, biomass burning and no aerosols) considering informations on depolarization ratio determined with the two cross-polarized elastic channels and on aerosols optical properties (extinction-to-backscatter ratio, aerosol backscatter and extinction coefficients) determined thanks to the nitrogen Raman channel at 387 nm. Aerosols optical properties can then been used for the assessment of mass concentrations which is crucial in case of hypothetical volcanic eruption. We will present the first results obtained with this new commercial lidar system. Daytime and nighttime performances of the system will be analyzed and compared with simulations from an instrumental model.

  1. Simulating aerosol-radiation-cloud feedbacks on meteorology and air quality over eastern China under severe haze conditionsin winter

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Wang, Y.; Hao, J.

    2015-03-01

    The aerosol-radiation-cloud feedbacks on meteorology and air quality over eastern China under severe winter haze conditions in January 2013 are simulated using the fully coupled online Weather Research and Forecasting/Chemistry (WRF-Chem) model. Three simulation scenarios including different aerosol configurations are undertaken to distinguish the aerosol's radiative (direct and semi-direct) and indirect effects. Simulated spatial and temporal variations of PM2.5 are generally consistent with surface observations, with a mean bias of -18.9 μg m-3 (-15.0%) averaged over 71 big cities in China. Comparisons between different scenarios reveal that aerosol radiative effects (direct effect and semi-direct effects) result in reductions of downward shortwave flux at the surface, 2 m temperature, 10 m wind speed and planetary boundary layer (PBL) height by up to 84.0 W m-2, 3.2°C, 0.8 m s-1, and 268 m, respectively. The simulated impact of the aerosol indirect effects is comparatively smaller. Through reducing the PBL height and stabilizing lower atmosphere, the aerosol effects lead to increases in surface concentrations of primary pollutants (CO and SO2). Surface O3 mixing ratio is reduced by up to 6.9 ppb (parts per billion) due to reduced incoming solar radiation and lower temperature, while the aerosol feedbacks on PM2.5 mass concentrations show some spatial variations. Comparisons of model results with observations show that inclusion of aerosol feedbacks in the model significantly improves model performance in simulating meteorological variables and improves simulations of PM2.5 temporal distributions over the North China Plain, the Yangtze River delta, the Pearl River delta, and central China. Although the aerosol-radiation-cloud feedbacks on aerosol mass concentrations are subject to uncertainties, this work demonstrates the significance of aerosol-radiation-cloud feedbacks for real-time air quality forecasting under haze conditions.

  2. Comparison of peak height of the F2-layer (hmF2) measurements with IRI-2012, IRI-2007 and IRI-2001 models predictions above Roquetes station (Spain) during the ascending phase of the solar cycle 24

    NASA Astrophysics Data System (ADS)

    Mohammed, Fahmi A.

    2015-09-01

    This research aims to validate IRI-2012 program and examine its accuracy in predicting peak height of the F2- layer (hmF2) above Roquetes. The seasonal hourly means of the ionosphere F2 peak height parameter (hmF2) above Roquetes station, Spain, (located at latitude close to the latitude of Iraq, 41°N) were analyzed and the results were compared with IRI-2012, IRI-2007 and IRI-2001, using CCIR (Comite´ Consultatif International des Radio Communications) option. The analysis covered quiet and disturbed days during various seasons of 2013 (the ascending phase of the solar cycle 24). In general, it is found that the predicted values of hmF2 overestimate the observed ones during all seasons, except Summer, whereas it underestimate at day hours. Also, it is found that the maximum percentage relative deviation of hmF2 occurred during Winter at 8 LT, while the minimum occurred during Autumnat 22 LT.

  3. A case study on the aerosol-meteorology feedback for Europe with WRF/Chem

    NASA Astrophysics Data System (ADS)

    Forkel, R.; Werhahn, J.; McKeen, S.; Peckham, S.; Grell, G.; Suppan, P.

    2012-04-01

    A main topic of the investigations with online coupled meteorology-chemistry models, such as WRF/Chem is the feedback of air pollution on meteorology. For the current case study three WRF/Chem simulations for Europe and the North Atlantic are compared: a baseline case without any aerosol feedback on meteorology, a simulation with the direct effect of aerosol on radiation included, and a simulation including the direct effect as well as the indirect aerosol effect. An episode covering June and July in 2006 was considered. WRF/Chem's 3-modal MADE/SORGAM aerosol module was applied for this investigation, which was motivated by the AQMEII (Air Quality Model Evaluation International Initiative) model inter-comparison exercise. For the simulation including just the direct effect, the aerosol-radiation induced changes in temperature, boundary layer height, and clouds ("semi-direct effect") were found to dominate after some time. Over Central Europe the mean reduction of global radiation due to aerosol extinction alone was mostly 3 - 7 W m-2, but changes in cloud cover due to semi-direct effects resulted in monthly mean changes of ± 50 W m-2. The inclusion of the indirect aerosol effect resulted in an up to 70% lower cloud water content and a significantly higher mean rain water content over the North Atlantic. The simulated low cloud droplet and CCN concentrations there are a result of the low aerosol concentrations in this area. However, model analysis suggests these results are sensitive to boundary conditions and a possible underestimation of aerosol sources over the North Atlantic. In spite of the higher aerosol concentrations over continental Europe, the inclusion of the indirect aerosol effect also results sometimes in smaller cloud droplet numbers than the fixed droplet number that is assumed in the absence of aerosol-cloud interactions. The agreement between observed and simulated global radiation over Europe was found to be better for cloudy conditions when the

  4. Single and multi-layered core-shell structures based on ZnO nanorods obtained by aerosol assisted chemical vapor deposition

    SciTech Connect

    Sáenz-Trevizo, A.; Amézaga-Madrid, P.; Pizá-Ruiz, P.; Antúnez-Flores, W.; Ornelas-Gutiérrez, C.; Miki-Yoshida, M.

    2015-07-15

    Core–shell nanorod structures were prepared by a sequential synthesis using an aerosol assisted chemical vapor deposition technique. Several samples consisting of ZnO nanorods were initially grown over TiO{sub 2} film-coated borosilicate glass substrates, following the synthesis conditions reported elsewhere. Later on, a uniform layer consisting of individual Al, Ni, Ti or Fe oxides was grown onto ZnO nanorod samples forming the so-called single MO{sub x}/ZnO nanorod core–shell structures, where MO{sub x} was the metal oxide shell. Additionally, a three-layer core–shell sample was developed by growing Fe, Ti and Fe oxides alternately, onto the ZnO nanorods. The microstructure of the core–shell materials was characterized by grazing incidence X-ray diffraction, scanning and transmission electron microscopy. Energy dispersive X-ray spectroscopy was employed to corroborate the formation of different metal oxides. X-ray diffraction outcomes for single core–shell structures showed solely the presence of ZnO as wurtzite and TiO{sub 2} as anatase. For the multi-layered shell sample, the existence of Fe{sub 2}O{sub 3} as hematite was also detected. Morphological observations suggested the existence of an outer material grown onto the nanorods and further microstructural analysis by HR-STEM confirmed the development of core–shell structures in all cases. These studies also showed that the individual Al, Fe, Ni and Ti oxide layers are amorphous; an observation that matched with X-ray diffraction analysis where no apparent extra oxides were detected. For the multi-layered sample, the development of a shell consisting of three different oxide layers onto the nanorods was found. Overall results showed that no alteration in the primary ZnO core was produced during the growth of the shells, indicating that the deposition technique used herein was and it is suitable for the synthesis of homogeneous and complex nanomaterials high in quality and purity. In addition

  5. [Height vertigo, fear of heights, acrophobia].

    PubMed

    Rennert, H

    1990-06-01

    Height vertigo (acrophobia) is a very frequent phenomenon being of interest for its physiological and psychological background, though usually only of limited significance in neuropsychiatry and otology. The different aspects as to its nature and origin are discussed. If acrophobia has developed into a conditioned reaction of avoidance with pressure of suffering, or acrophobia in persons, who have to work at heights, behavior therapeutic measures with systematic desensibilisation, starting from an imaginative training, are indicated.

  6. Comparison of Summer and Winter California Central Valley Aerosol Distributions from Lidar and MODIS Measurements

    NASA Technical Reports Server (NTRS)

    Lewis, Jasper R., Jr.; DeYoung, Russell J.; Chu, D. Allen

    2010-01-01

    Aerosol distributions from two aircraft lidar campaigns conducted in the California Central Valley are compared in order to identify seasonal variations. Aircraft lidar flights were conducted in June 2003 and February 2008. While the PM2.5 concentration is highest in the winter, the aerosol optical depth measured from MODIS is highest in the summer. A seasonal comparison shows that PM2.5 in the winter can exceed summer PM2.5 by 55%, while summer AOD exceeds winter AOD by 43%. Higher temperatures wildfires in the summer produce elevated aerosol layers that are detected by satellite measurements, but not surface particulate matter monitors. Measurements of the boundary layer height from lidar instruments are necessary to incorporate satellite measurements with air quality measurements.

  7. Impact of Anthropogenic Aerosol on the Properties of Shallow Maritime Cumulus Clouds

    NASA Astrophysics Data System (ADS)

    Gao, L.; Wilcox, E. M.; Shan, Y.

    2015-12-01

    The northern Indian Ocean region is frequently covered by cumulus clouds that are responsible for moistening the boundary layer and contribute to tropical deep convection. Because this region is uniquely located close to the highly polluted Indian plateau, air mass with high aerosol concentration can be easily transported to this area. These small cumulus clouds, coupled with the effects of aerosol, have a large potential to affect the regional and global albedo. The aerosol effects on cloud properties and atmospheric structures are examined in this work, using the UAV (Unmanned Aerial Vehicle) data that are observed from CARDEX (Cloud, Aerosol, Radiative forcing, Dynamics EXperiment) and MAC (Maldives Autonomous unmanned aerial vehicle Campaign). On average, the high polluted cases show warmer temperature through the entire atmospheric column and higher relative humidity in boundary layer. The maximum temperature difference between high and low polluted cases can be found around the cloud layer altitude. In addition, the height of sub-cloud mixed layer is higher in low polluted cases. Clouds in high polluted cases are generally becoming narrower and taller than those in low polluted cases, and are associated with greater cloud water content and higher cloud droplet number concentrations, especially in small droplet range (diameters less than 10 micrometers). Meanwhile, the effective radius of cloud droplets decreases as the aerosol concentration increases. These facts indicate that the high polluted clouds are on average brighter with higher albedo.

  8. Numerical studies of microphysical modulations of stratospheric aerosol within ROMIC-ROSA

    NASA Astrophysics Data System (ADS)

    Hommel, René; von Savigny, Christian; Rozanov, Alexei; Burrows, John; Zalach, Jakob

    2016-04-01

    The stratospheric aerosol layer (so-called Junge layer) is an inherent part of the Brewer-Dobson circulation (BDC). Stratospheric aerosols play a large role in the Earth's climate system because they interact with catalytic cycles depleting ozone, directly alter the atmosphere's radiative balance and modulate the strength of polar vortices, in particular when this system is perturbed. In terms of mass the layer is predominantly composed of liquid sulphate-water droplets and is fed from the oxidation of gaseous precursors reaching the stratosphere either by direct volcanic injections (mainly supplying SO2) or troposphere-stratosphere exchange processes. In volcanically quiescent periods, latter processes predominantly maintain the so-called background state of aerosol layer through oxidation of OCS above 22 km, and SO2 below. The Junge layer begins to develop 2-3 km above the tropopause and reaches a height of about 35 km, with a largest vertical extent in the tropics and spring-time polar regions. Above the TTL, the layer's vertical extent varies between 2 km and 8 km (about 35% of its mean vertical expansion), depending on the phase of the QBO. The QBO-induced meridional circulation, overlying the BDC, and accompanied signatures in the stratospheric temperature directly affect the life cycle of stratospheric aerosol. Mainly by modulating the equilibrium between microphysical processes which maintain the layer. Effects caused by QBO modulations of the advective transport in the upwelling region of the BDC are smaller and difficult to quantify, because the overlying sedimentation of aerosol is also being modulated and counteract the aerosol lofting. Here we show results from numerical studies performed within the project ROMIC-ROSA (Role of Stratospheric Aerosol in Climate and Atmospheric Science). We further explored relationships between QBO forcing and aerosol processes in the lower stratosphere. We examined whether similar process interferences can be caused by

  9. Cumulus cloud venting of mixed layer ozone

    NASA Technical Reports Server (NTRS)

    Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

    1985-01-01

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

  10. Comparison of Aerosol Properties within and above the ABL at the ARM Program's SGP Site

    SciTech Connect

    Monache, L.D.; Perry, K.D.; Cederwall, R.T.

    2002-02-26

    The goal of this study was to determine under what conditions, if any, measurements of aerosol properties made at the Earth's surface are representative of the aerosol properties within the column of air above the surface. This project used data from the Atmospheric Radiation Measurement (ARM) site at the Southern Great Plains (SGP) site (Stokes and Schwartz 1994), which is one of the only locations in the world where ground-based and in situ airborne measurements of atmospheric aerosol are made on a routine basis. All flight legs in the one-year period from March 2000 to March 2001 were categorized as either within or above the atmospheric boundary layer (ABL) using an objective mixing height determination technique. The correlations between the aerosol properties measured at the surface and those measured within and above the ABL were then computed. The conclusion of this comparison is that the aerosol extensive properties (those that depend upon the amount of aerosol that is present in the atmosphere, i.e., either the number or mass concentrations), and intensive properties (those that do not depend upon the amount of aerosol present) measured at the surface are representative of values within the ABL, but not within the free atmosphere.

  11. Radiative effects of aerosols on the environment in China

    NASA Astrophysics Data System (ADS)

    Yu, Hongbin

    Anthropogenic emissions and concentrations of aerosol precursors and aerosols over China are among the highest in major countries of the world. Due to large emissions of soot and dust, aerosol absorption is high. Based on the observed direct and diffuse irradiance, a single scattering albedo of about 0.8 is derived for two large agri/eco/industrial areas. Aerosol direct effect can exert various environmental impacts in China. Photochemical activities in the atmospheric boundary layer (ABL) are significantly reduced because of reductions in photolysis rates and in emissions of biogenic hydrocarbons. Crop yields under optimal conditions can be reduced due to the reduction in surface solar irradiance. The most significant aerosol radiative perturbation is in changing the air-surface interaction and diurnal evolution of ABL. Reductions in various surface heat fluxes due to aerosols depend on soil moisture. Over a relatively dry surface, the evaporation has a small change, leading to the largest decrease of surface skin temperature at noon. Over a relatively wet surface, a substantial reduction in evaporation results in the largest surface cooling in the early morning. The diurnal temperature range (DTR) can be reduced by an amount comparable to the observed decrease of DTR. The longwave absorption of aerosols can lead to an increase of the daily minimum temperature and contributes to about 20% of the decrease in the DTR. The near-surface air temperature has the largest cooling in the early morning because the ABL is shallow and the temperature is sensitive to the radiative perturbation. As a result of the reduced sensible heat flux, the surface layer becomes more stable. Moreover, the aerosol heating enhances the stabilization of surface layer and in turn further reduces the sensible heat flux. As a result the ABL height can be reduced substantially. This will have many important ramifications, including trapping/accumulation of air pollutants, and perturbing the water

  12. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  13. Atomic layer epitaxy of Ruddlesden-Popper SrO(SrTiO{sub 3}){sub n} films by means of metalorganic aerosol deposition

    SciTech Connect

    Jungbauer, M.; Hühn, S.; Moshnyaga, V.; Egoavil, R.; Tan, H.; Verbeeck, J.; Van Tendeloo, G.

    2014-12-22

    We report an atomic layer epitaxial growth of Ruddlesden-Popper (RP) thin films of SrO(SrTiO{sub 3}){sub n} (n = ∞, 2, 3, 4) by means of metalorganic aerosol deposition (MAD). The films are grown on SrTiO{sub 3}(001) substrates by means of a sequential deposition of Sr-O/Ti-O{sub 2} atomic monolayers, monitored in-situ by optical ellipsometry. X-ray diffraction and transmission electron microscopy (TEM) reveal the RP structure with n = 2–4 in accordance with the growth recipe. RP defects, observed by TEM in a good correlation with the in-situ ellipsometry, mainly result from the excess of SrO. Being maximal at the film/substrate interface, the SrO excess rapidly decreases and saturates after 5–6 repetitions of the SrO(SrTiO{sub 3}){sub 4} block at the level of 2.4%. This identifies the SrTiO{sub 3} substrate surface as a source of RP defects under oxidizing conditions within MAD. Advantages and limitations of MAD as a solution-based and vacuum-free chemical deposition route were discussed in comparison with molecular beam epitaxy.

  14. A novel approach to Lagrangian sampling of marine boundary layer cloud and aerosol in the northeast Pacific: case studies from CSET

    NASA Astrophysics Data System (ADS)

    Mohrmann, J.; Albrecht, B. A.; Bretherton, C. S.; Ghate, V. P.; Zuidema, P.; Wood, R.

    2015-12-01

    The Cloud System Evolution in the Trades (CSET) field campaign took place during July/August 2015 with the purpose of characterizing the cloud, aerosol and thermodynamic properties of the northeast Pacific marine boundary layer. One major science goal of the campaign was to observe a Lagrangian transition from thin stratocumulus (Sc) upwind near California to trade cumulus (Cu) nearer to Hawaii. Cloud properties were observed from the NSF/NCAR Gulfstream V research plane (GV) using the HIAPER Cloud Radar (HCR) and the HIAPER Spectral Resolution Lidar (HSRL), among other instrumentation. Aircraft observations were complemented by a suite of satellite-derived products. To observe a the evolution of airmasses over the course of two days, upwind regions were sampled on an outbound flight to from Sacramento, CA, to Kona, HI. The sampled airmasses were then tracked using HYSPLIT trajectories based on GFS model forecasts, and the return flight to California was planned to intercept those airmasses, using satellite observation to track cloud evolution in the interim. This approach required that trajectories were reasonably stable up to 3 days prior to final sampling, and also that forecast trajectories were in agreement with post-flight analysis and visual cloud feature tracking. The extent to which this was realised, and hence the validity of this new approach to Lagrangian airmass observation, is assessed here. We also present results showing that a Sc-Cu airmass transition was consistently observed during the CSET study using measurements from research flights and satellite.

  15. Relating Aerosol Profile and Column Measurements to Surface Concentrations: What Have We Learned from Discover-AQ?

    NASA Astrophysics Data System (ADS)

    Hoff, R. M.

    2014-12-01

    One research goal of the Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) mission was to determine sufficient column profile measurements to relate column integrated quantities such as Aerosol Optical Depth to surface concentrations. I will review the relationship between AOD and PM2.5 at the surface. DISCOVER-AQ in Baltimore, the San Joaquin Valley, Houston and Denver revealed quite different conditions for determining this relationship. In each case, the surface reflectivity made determination of aerosol optical depth challenging, but upward looking columns of aerosol optical depth from sunphotometers provided confirmation of the AOD results from space. In Baltimore, AOD fields reflected PM2.5 concentrations well. In California, however, the low boundary layer heights and dominance of nitrate and organic aerosols made the AOD fields less predictive of PM2.5. In California and Colorado, hydration of the aerosol varied dramatically with aerosol type (especially smoke and dust) and revealed that without an understanding of the degree of aerosol hydration with aerosol composition, the relationship between AOD and PM2.5 will continue to be a challenge. Model predictions in the Baltimore-Washington study are relatively disappointing in helping define the needed physics between the optical and microphysical properties. An overview of the measurements from DISCOVER-AQ which will help define the needed information in a more general case in the future will be given.

  16. A-Train satellite measurements of dust aerosol distributions over northern China

    NASA Astrophysics Data System (ADS)

    Wang, Hongbin; Zhang, Lei; Cao, Xianjie; Zhang, Zhiwei; Liang, Jiening

    2013-06-01

    Horizontal and vertical distributions of dust aerosols over northern China were investigated for the period June 2006 to May 2011 using A-Train satellite constellation data and ground-based measurements. Surface observations at 675 meteorological stations showed that dust events occurred most frequently in the Taklamakan and Gobi deserts. In the Taklamakan Desert, the dust aerosol content was high throughout the year, as seen from the distributions of the Moderate-Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD) and the Ozone Monitoring Instrument (OMI) UV-absorption aerosol index (AAI). In the Taklamakan and Gobi deserts, the AOD and AAI reached maxima in spring and minima in winter. In the eastern part of northern China, AOD reached a maximum in summer and a minimum in fall, whereas AAI was high in winter and spring and low in summer and fall due to seasonal differences in the main aerosol type. The dust observations revealed strong seasonal variations in dust coverage area and height, with maxima in spring and summer and minima in fall and winter. The transportation of dust aerosols in all seasons was confined largely between 35°N and 45°N. The mean height of the dust layer top varied and showed strong seasonal variation in all regions, with values higher than 4km in spring and about 2km in winter. The Taklamakan Desert experienced higher occurrence of dust events than other regions throughout the year. Dust occurrence decreased dramatically over the eastern part of northern China in summer because of surface vegetation and precipitation. Simulation results by the HYSPLIT model were similar to the distribution of dust aerosols observed by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) during the same period.

  17. Radioactive Aerosols as an Index of Air Pollution in the City of Thessaloniki, Greece

    SciTech Connect

    Ioannidou, A.; Papastefanou, C.

    2010-01-21

    This study summarizes results of an investigation done in order to find out how the radioactive aerosols of {sup 7}Be could serve as indicators of air pollution conditions. Beryllium-7 is a cosmic-ray produced radionuclide with an important fraction of its production to take place in the upper troposphere. Once it is formed is rapidly associated with submicron aerosol particles and participates in the formation and growth of the accumulation mode aerosols, which is a major reservoir of pollutants in the atmosphere. In order to define any influence of AMAD of {sup 7}Be aerosols by air pollution conditions, the aerodynamic size distribution of {sup 7}Be aerosols was determined by collecting samples at different locations in the suburban area of the city of Thessaloniki, including rural areas, industrial areas, high elevations, marine environment and the airport area. The aerodynamic size distribution of {sup 7}Be aerosols in different locations was obtained by using Andersen 1-ACFM cascade impactors and the Activity Median Aerodynamic Diameter (AMAD) was determined. Some dependency of the AMADs on height has been observed, while in near marine environment the {sup 7}Be activity size distribution was dominant in the upper size range of aerosol particles. Low AMADs as low as 0.62 to 0.74 {mu}m of {sup 7}Be aerosols have been observed at locations characterized with relative low pollution, while it is concluded that in the activity size distribution of ambient aerosols, {sup 7}Be changes to larger particle sizes in the presence of pollutants, since low AMADs of {sup 7}Be aerosols have been observed at low polluted locations. Preliminary data of simultaneous measurements of {sup 214}Pb and {sup 212}Pb with gaseous air pollutants CO, NO, NO{sub X}, SO{sub 2} and total suspended particulate matter (TSP) show that radon decay products near the ground could be a useful index of air pollution potential conditions and transport processes in the boundary layer.

  18. A Model for the Transport of Sea-Spray Aerosols in the Coastal Zone

    NASA Astrophysics Data System (ADS)

    Piazzola, J.; Tedeschi, G.; Demoisson, A.

    2015-05-01

    We study the dynamics of sea-spray particles in the coastal region of La Reunion Island on the basis of numerical simulations using the transport aerosol model MACMod (Marine Aerosol Concentration Model) and a survey of the aerosol size distributions measured at four locations at two different heights in the north-west part of the island. This allows evaluation of the performance of our model in case of pure marine air masses with implementation of accurate boundary conditions. First of all, an estimate of the aerosol concentration at 10-m height at the upwind boundary of the calculation domain is obtained using a revisited version of the MEDEX (Mediterranean Extinction) model. Estimates of the vertical profile of aerosol concentrations are then provided using aerosol data obtained at two different heights at the upwind boundary of the calculation domain. A parametrization of the vertical profiles of aerosol concentrations for maritime environment is proposed. The results are then compared to the vertical profiles of 0.532 m aerosol particle extinction coefficient obtained from lidar data provided by the Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) and also to the data provided by the Aerosol Robotic Network (AERONET). This allows validation of the complete vertical profiles in the mixed layer and shows the validity of satellite data for determination of the vertical profiles. Two kinds of simulation were made: one without a particle advection flux at the upwind boundary of the numerical domain, whereas the second simulation was made with a particle advection flux. In the first case, the influence of the distance to the shoreline on the local sea-spray dynamics is investigated. In the second set of simulation, the particles issued from the local production in the surf zone near the shoreline are mixed with aerosols advected from the remote ocean. A good agreement between the model calculations using our boundary conditions and the data was found. The

  19. Particle concentrations and number size distributions in the planetary boundary layer derived from airship based measurements

    NASA Astrophysics Data System (ADS)

    Tillmann, Ralf; Zhao, Defeng; Ehn, Mikael; Hofzumahaus, Andreas; Holland, Frank; Rohrer, Franz; Kiendler-Scharr, Astrid; Wahner, Andreas

    2014-05-01

    Atmospheric particles play a key role for regional and global climate due to their direct and indirect radiative forcing effects. The concentration and size of the particles are important variables to these effects. Within the continental planetary boundary layer (PBL) the particle number size distribution is influenced by meteorological parameters, local sinks and sources resulting in variable spatial distributions. However, measurements of particle number size distributions over a broad vertical range of the PBL are rare. The airship ZEPPELIN NT is an ideal platform to measure atmospheric aerosols on a regional scale within an altitude range up to 1000 m. For campaigns in the Netherlands, Northern Italy and South Finland in 2012 and 2013 the airship was deployed with a wide range of instruments, including measurements of different trace gases, short lived radicals, solar radiation, aerosols and meteorological parameters. Flights were carried out at different times of the day to investigate the influence of the diurnal evolution of the PBL on atmospheric trace gases and aerosols. During night and early morning hours the concentration and size distribution of atmospheric particles were found to be strongly influenced by the layered structure of the PBL, i.e. the nocturnal boundary layer and the residual layer. Within the residual layer particle concentrations stay relatively constant as this layer is decoupled from ground sources. The particles persist in the accumulation mode as expected for an aged aerosol. In the nocturnal boundary layer particle concentrations and size are more dynamic with higher concentrations than in the residual layer. A few hours after sunrise, the layered structure of the PBL intermixes. During daytime the PBL is well mixed and a negative concentration gradient with increasing height is observed. Several height profiles at different times of the day and at different locations in Europe were measured. The aerosol measurements will be

  20. Measurements of the HO2 uptake coefficient onto aqueous salt and organic aerosols and interpretation using the kinetic multi-layer model of aerosol surface and bulk chemistry (KM-SUB)

    NASA Astrophysics Data System (ADS)

    Matthews, P. S. J.; Berkemeier, T.; George, I. J.; Whalley, L. K.; Moon, D. R.; Ammann, M.; Baeza-Romero, M. T.; Poeschl, U.; Shiraiwa, M.; Heard, D. E.

    2014-12-01

    HO2 is closely coupled with OH which is responsible for the majority of the oxidation in the troposphere. Therefore, it is important to be able to accurately predict OH and HO2 concentrations. However, many studies have reported a large discrepancy between HO2 radical concentrations measured during field campaigns and predicted by constrained box models using detailed chemical mechanisms (1,2). However, there have been very few laboratory studies (3,4) on HO2 uptake by aerosols and the rates and mechanism is still uncertain. The HO2 uptake coefficients were measured for deliquesced ammonium nitrate and sodium chloride aerosols and copper doped sucrose aerosols. The measurements were performed using an aerosol flow tube coupled to a Fluorescence Assay by Gas Expansion (FAGE) detector. By either placing the HO2 injector in set positions and varying the aerosol concentration or by moving it along the flow tube at given aerosol concentrations, uptake coefficients could be measured. The aerosols were generated using an atomiser and the total aerosol surface area was measured using a SMPS. Larger uptake coefficients were measured at shorter times and lower HO2 concentrations for aqueous salt aerosols. The time dependence was able to be modelled by the KM-SUB model (5) as the HO2 concentration decreases along the flow tube and the HO2 uptake mechanism is known to be a second order reaction. Measurements have shown that at higher HO2 concentrations there was also more H2O2 exiting the injector which could convert back to HO2 if trace amounts of metals are present within the aerosol via Fenton reactions. Preliminary results have shown that the inclusion of a Fenton-like reaction within the KM-SUB model has the potential to explain the apparent HO2 concentration dependence. Finally, the KM-SUB model has been used to demonstrate that the increase in uptake coefficient observed when increasing the relative humidity for copper doped sucrose aerosols could be explained by an

  1. 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.; Hipskind, R. Stephen (Technical Monitor)

    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.

  2. The importance of plume rise on the concentrations and atmospheric impacts of biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Walter, Carolin; Freitas, Saulo R.; Kottmeier, Christoph; Kraut, Isabel; Rieger, Daniel; Vogel, Heike; Vogel, Bernhard

    2016-07-01

    We quantified the effects of the plume rise of biomass burning aerosol and gases for the forest fires that occurred in Saskatchewan, Canada, in July 2010. For this purpose, simulations with different assumptions regarding the plume rise and the vertical distribution of the emissions were conducted. Based on comparisons with observations, applying a one-dimensional plume rise model to predict the injection layer in combination with a parametrization of the vertical distribution of the emissions outperforms approaches in which the plume heights are initially predefined. Approximately 30 % of the fires exceed the height of 2 km with a maximum height of 8.6 km. Using this plume rise model, comparisons with satellite images in the visible spectral range show a very good agreement between the simulated and observed spatial distributions of the biomass burning plume. The simulated aerosol optical depth (AOD) with data of an AERONET station is in good agreement with respect to the absolute values and the timing of the maximum. Comparison of the vertical distribution of the biomass burning aerosol with CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) retrievals also showed the best agreement when the plume rise model was applied. We found that downwelling surface short-wave radiation below the forest fire plume is reduced by up to 50 % and that the 2 m temperature is decreased by up to 6 K. In addition, we simulated a strong change in atmospheric stability within the biomass burning plume.

  3. A study of aerosol optical properties during ozone pollution episodes in 2013 over Shanghai, China

    NASA Astrophysics Data System (ADS)

    Shi, Chanzhen; Wang, Shanshan; Liu, Rui; Zhou, Rui; Li, Donghui; Wang, Wenxin; Li, Zhengqiang; Cheng, Tiantao; Zhou, Bin

    2015-02-01

    Aerosol optical property is essential to the tropospheric ozone formation mechanism while it was rarely measured in ozone-rich environment for a specific study. With the retrieved products of the sun-photometer, a comparative investigation was conducted on aerosol optical depth (AOD), single scattering albedo (SSA) and size distribution during ozone-polluted episodes and clean background. Contrary to expectations, aerosol loading was found to be positively-correlated with ozone concentration: daily averaged AOD at 500 nm in ozone episodes (~ 0.78) displayed 2.4 times higher than that in clean days (~ 0.32). Large Ångström exponent (~ 1.51) along with heavy aerosol loading indicated a considerable impact of fine particles on optical extinction. The dynamic diurnal fluctuation of these parameters also implied a complex interaction between aerosols and photo-chemical reactions. The bimodal lognormal distribution pattern for aerosol size spectra exhibited in both ozone-polluted and clean days. The occurrence of maximum volume concentration (~ 0.28) in fine mode (radius < 0.6 μm) was observed at 3 p.m. (local time), when ozone was substantially generated. Pronounced scattering feature of aerosol was reproduced in high-concentration ozone environment. SSA tended to increase continuously from morning (~ 0.91 at 440 nm) to afternoon (~ 0.99), which may be associated with secondary aerosol formation. The scattering aerosol (with moderately high aerosol loading) may favor the ozone formation through increasing solar flux in boundary layer. Utilizing the micro-pulse lidar (MPL), a more developed planet boundary layer (PBL, top height ~ 1.96 km) was discovered during ozone-polluted days than clean condition (~ 1.4 km). In episodes, the maximum extinction ratio (~ 0.5 km- 1) was presented at a height of 1.2 km in the late afternoon. The humidity profile by sounding also showed the extreme value at this altitude. It suggested that optical extinction was mainly attributed to

  4. Lidar-Radiometer Inversion Code (LIRIC) for the retrieval of vertical aerosol properties from combined lidar/radiometer data: development and distribution in EARLINET

    NASA Astrophysics Data System (ADS)

    Chaikovsky, A.; Dubovik, O.; Holben, B.; Bril, A.; Goloub, P.; Tanré, D.; Pappalardo, G.; Wandinger, U.; Chaikovskaya, L.; Denisov, S.; Grudo, Y.; Lopatin, A.; Karol, Y.; Lapyonok, T.; Amiridis, V.; Ansmann, A.; Apituley, A.; Allados-Arboledas, L.; Binietoglou, I.; Boselli, A.; D'Amico, G.; Freudenthaler, V.; Giles, D.; Granados-Muñoz, M. J.; Kokkalis, P.; Nicolae, D.; Oshchepkov, S.; Papayannis, A.; Perrone, M. R.; Pietruczuk, A.; Rocadenbosch, F.; Sicard, M.; Slutsker, I.; Talianu, C.; De Tomasi, F.; Tsekeri, A.; Wagner, J.; Wang, X.

    2015-12-01

    This paper presents a detailed description of LIRIC (LIdar-Radiometer Inversion Code) algorithm for simultaneous processing of coincident lidar and radiometric (sun photometric) observations for the retrieval of the aerosol concentration vertical profiles. As the lidar/radiometric input data we use measurements from European Aerosol Research Lidar Network (EARLINET) lidars and collocated sun-photometers of Aerosol Robotic Network (AERONET). The LIRIC data processing provides sequential inversion of the combined lidar and radiometric data by the estimations of column-integrated aerosol parameters from radiometric measurements followed by the retrieval of height-dependent concentrations of fine and coarse aerosols from lidar signals using integrated column characteristics of aerosol layer as a priori constraints. The use of polarized lidar observations allows us to discriminate between spherical and non-spherical particles of the coarse aerosol mode. The LIRIC software package was implemented and tested at a number of EARLINET stations. Intercomparison of the LIRIC-based aerosol retrievals was performed for the observations by seven EARLNET lidars in Leipzig, Germany on 25 May 2009. We found close agreement between the aerosol parameters derived from different lidars that supports high robustness of the LIRIC algorithm. The sensitivity of the retrieval results to the possible reduction of the available observation data is also discussed.

  5. Lidar-Radiometer Inversion Code (LIRIC) for the retrieval of vertical aerosol properties from combined lidar/radiometer data: development and distribution in EARLINET

    NASA Astrophysics Data System (ADS)

    Chaikovsky, Anatoli; Dubovik, Oleg; Holben, Brent; Bril, Andrey; Goloub, Philippe; Tanré, Didier; Pappalardo, Gelsomina; Wandinger, Ulla; Chaikovskaya, Ludmila; Denisov, Sergey; Grudo, Jan; Lopatin, Anton; Karol, Yana; Lapyonok, Tatsiana; Amiridis, Vassilis; Ansmann, Albert; Apituley, Arnoud; Allados-Arboledas, Lucas; Binietoglou, Ioannis; Boselli, Antonella; D'Amico, Giuseppe; Freudenthaler, Volker; Giles, David; José Granados-Muñoz, María; Kokkalis, Panayotis; Nicolae, Doina; Oshchepkov, Sergey; Papayannis, Alex; Perrone, Maria Rita; Pietruczuk, Alexander; Rocadenbosch, Francesc; Sicard, Michaël; Slutsker, Ilya; Talianu, Camelia; De Tomasi, Ferdinando; Tsekeri, Alexandra; Wagner, Janet; Wang, Xuan

    2016-03-01

    This paper presents a detailed description of LIRIC (LIdar-Radiometer Inversion Code) algorithm for simultaneous processing of coincident lidar and radiometric (sun photometric) observations for the retrieval of the aerosol concentration vertical profiles. As the lidar/radiometric input data we use measurements from European Aerosol Research Lidar Network (EARLINET) lidars and collocated sun-photometers of Aerosol Robotic Network (AERONET). The LIRIC data processing provides sequential inversion of the combined lidar and radiometric data. The algorithm starts with the estimations of column-integrated aerosol parameters from radiometric measurements followed by the retrieval of height dependent concentrations of fine and coarse aerosols from lidar signals using integrated column characteristics of aerosol layer as a priori constraints. The use of polarized lidar observations allows us to discriminate between spherical and non-spherical particles of the coarse aerosol mode.The LIRIC software package was implemented and tested at a number of EARLINET stations. Intercomparison of the LIRIC-based aerosol retrievals was performed for the observations by seven EARLINET lidars in Leipzig, Germany on 25 May 2009. We found close agreement between the aerosol parameters derived from different lidars that supports high robustness of the LIRIC algorithm. The sensitivity of the retrieval results to the possible reduction of the available observation data is also discussed.

  6. Aerosol radiative effects on the meteorology and distribution of pollutants in the Mexico City Metropolitan Area during MCMA-2006/MILAGRO Campaign

    NASA Astrophysics Data System (ADS)

    Li, Guohui; Bei, Naifang; Molina, Luisa

    2013-04-01

    Aerosols scatter or absorb incoming solar radiation, perturb the temperature structure of the atmosphere, and impact meteorological fields and further the distribution of gas phase species and aerosols. In the present study, the aerosol radiative effects on the meteorology and photochemistry in the Mexico City Metropolitan Area (MCMA) are investigated using the WRF-CHEM model during the period from March 24th to 29th associated with the MILAGRO-2006 campaign. Aerosols decrease incoming solar radiation by up to 20% and reduce the surface temperature by up to 0.5 °C due to scattering and absorbing the incoming solar radiation in Mexico City. The absorption of black carbon aerosols can also enhance slightly the temperature in the planetary boundary layer (PBL). Generally, the change of the PBL height in the city is less than 200 m during daytime due to the aerosol-induced perturbation of temperature profile. Wind fields are also adjusted with the variation of temperatures, but all the aerosol-induced meteorological changes cannot significantly influence the distribution of pollutants in the city. In addition, when convective events occur in the city, the aerosol radiative effects reduce the convective available potential energy (CAPE) and the convective precipitation is generally decreased. Further studies still need to be performed to evaluate the aerosol indirect effect on precipitation in Mexico City.

  7. Influence of the voltage waveform during nanocomposite layer deposition by aerosol-assisted atmospheric pressure Townsend discharge

    NASA Astrophysics Data System (ADS)

    Profili, J.; Levasseur, O.; Naudé, N.; Chaneac, C.; Stafford, L.; Gherardi, N.

    2016-08-01

    This work examines the growth dynamics of TiO2-SiO2 nanocomposite coatings in plane-to-plane Dielectric Barrier Discharges (DBDs) at atmospheric pressure operated in a Townsend regime using nebulized TiO2 colloidal suspension in hexamethyldisiloxane as the growth precursors. For low-frequency (LF) sinusoidal voltages applied to the DBD cell, with voltage amplitudes lower than the one required for discharge breakdown, Scanning Electron Microscopy of silicon substrates placed on the bottom DBD electrode reveals significant deposition of TiO2 nanoparticles (NPs) close to the discharge entrance. On the other hand, at higher frequencies (HF), the number of TiO2 NPs deposited strongly decreases due to their "trapping" in the oscillating voltage and their transport along the gas flow lines. Based on these findings, a combined LF-HF voltage waveform is proposed and used to achieve significant and spatially uniform deposition of TiO2 NPs across the whole substrate surface. For higher voltage amplitudes, in the presence of hexamethyldisiloxane and nitrous oxide for plasma-enhanced chemical vapor deposition of inorganic layers, it is found that TiO2 NPs become fully embedded into a silica-like matrix. Similar Raman spectra are obtained for as-prepared TiO2 NPs and for nanocomposite TiO2-SiO2 coating, suggesting that plasma exposure does not significantly alter the crystalline structure of the TiO2 NPs injected into the discharge.

  8. On measurements of aerosol-gas composition of the atmosphere during two expeditions in 2013 along the Northern Sea Route

    NASA Astrophysics Data System (ADS)

    Sakerin, S. M.; Bobrikov, A. A.; Bukin, O. A.; Golobokova, L. P.; Pol'kin, Vas. V.; Pol'kin, Vik. V.; Shmirko, K. A.; Kabanov, D. M.; Khodzher, T. V.; Onischuk, N. A.; Pavlov, A. N.; Potemkin, V. L.; Radionov, V. F.

    2015-11-01

    We presented the results of expedition measurements of the set of physical-chemical characteristics of atmospheric aerosol in areas of the Arctic and Far East seas, performed onboard RV Akademik Fedorov (17 August-22 September 2013) and RV Professor Khljustin (24 July-7 September 2013). The specific features of spatial distribution and time variations of aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34-2.14 μm and boundary layer height, aerosol and black carbon mass concentrations, and disperse and chemical composition of aerosol are discussed. Over the Arctic Ocean (on the route of RV Akademik Fedorov) there is a decrease in aerosol and black carbon concentrations in a northeastern direction: higher values were observed in the region of Spitsbergen and near the Kola Peninsula; and minimum values were observed at northern margins of the Laptev Sea. Average AOD (0.5 μm) values in this remote region were 0.03; the aerosol and black carbon mass concentrations were 875 and 22 ng m-3, respectively. The spatial distributions of most aerosol characteristics over Far East seas show their latitudinal decrease in the northern direction. On transit of RV Professor Khljustin from the Japan Sea to the Chukchi Sea, the aerosol number concentration decreased on average from 23.7 to 2.5 cm-3, the black carbon mass concentration decreased from 150 to 50 ng m-3, and AOD decreased from 0.19 to 0.03. We analyzed the variations in the boundary layer height, measured by ship-based lidar: the average value was 520 m, and the maximal value was 1200 m. In latitudinal distribution of the boundary layer height, there is a characteristic minimum at a latitude of ~ 55° N. For water basins of eight seas, we present the chemical compositions of the water-soluble aerosol fraction (ions, elements) and small gas-phase species, as well as estimates of their vertical fluxes. It is shown that substances are mainly (75-89 %) supplied from the atmosphere to the sea

  9. On measurements of aerosol-gas composition of the atmosphere during two expeditions in 2013 along Northern Sea Route

    NASA Astrophysics Data System (ADS)

    Sakerin, S. M.; Bobrikov, A. A.; Bukin, O. A.; Golobokova, L. P.; Pol'kin, Vas. V.; Pol'kin, Vik. V.; Shmirko, K. A.; Kabanov, D. M.; Khodzher, T. V.; Pavlov, A. N.; Potemkin, V. L.; Radionov, V. F.

    2015-06-01

    We presented the results of expedition measurements of the set of physical-chemical characteristics of atmospheric aerosol in water basins of Arctic and Far East seas, performed onboard RV Akademik Fedorov (17 August-22 September 2013) and RV Professor Khljustin (24 July-7 September 2013). The specific features of spatial distribution and time variations of aerosol optical depth (AOD) of the atmosphere in the wavelength range of 0.34-2.14 μm and boundary layer height, aerosol and black carbon mass concentrations, and disperse and chemical composition of aerosol are discussed. Over the Arctic Ocean (on the route of RV Akademik Fedorov) there is a decrease in aerosol and black carbon concentrations in northeastern direction: higher values were observed in the region of Spitsbergen and near the Kola Peninsula; and minimum values were observed at northern margins of the Laptev Sea. Average AOD (0.5 μm) values in this remote region were 0.03; the aerosol and black carbon mass concentrations were 875 and 22 ng m-3, respectively. The spatial distributions of most aerosol characteristics over Far East seas show their latitudinal decrease in the northern direction. On transit of RV Professor Khljustin from Japan to Chukchi Sea, the aerosol number concentration decreased, on the average, from 23.7 to 2.5 cm-3, the black carbon mass concentration decreased from 150 to 50 ng m-3, and AOD decreased from 0.19 to 0.03. We analyzed the variations in the boundary layer height, measured by ship-based lidar: the average value was 520 m, and the maximal value was 1200 m. In latitudinal distribution of the boundary layer height, there is a characteristic minimum at latitude of ∼ 55° N. For water basins of eight seas, we present the chemical compositions of water-soluble aerosol fraction (ions, elements) and small gaseous impurities, as well as estimates of their vertical fluxes. It is shown that substances are mainly (75-89 %) supplied from the atmosphere to the sea surface

  10. Aerosol Optical Properties During The SAMUM-2 Experiment

    NASA Astrophysics Data System (ADS)

    Toledano, C.; Freudenthaler, V.; Gross, S.; Seefeldner, M.; Gasteiger, J.; Garhammer, M.; Esselborn, M.; Wiegner, M.; Koepke, P.

    2009-03-01

    A field campaign of the Saharan Mineral Dust Experiment (SAMUM-2) took place in the Cape Verde islands in January-February 2008, to investigate the properties of long-range transported dust over the Atlantic. The Meteorological Institute of the University of Munich deployed a set of active and passive remote sensing instruments: one sun photometer, for the measurement of the direct sun irradiance and sky radiances; a broad-band UV radiometer; and 2 tropospheric lidar systems. The measurements were made in close cooperation with the other participating groups. During the measurement period the aerosol scenario over Cape Verde mostly consisted of a dust layer below 2 km and a smoke layer above 2 km height. The Saharan dust arrived in the site from the NE, whereas the smoke originated in the African equatorial region is transported from the SE. The aerosol load was also very variable over this area, with AOD (500 nm) ranging from 0.04 to 0.74. The optical properties of the layers are shown: extinction and particle depolarization ratio profiles at 3 wavelengths, as well as aerosol optical depth (in the range 340-1550 nm), Ångström exponent, size distribution and single scattering albedo.

  11. Raman lidar/AERI PBL Height Product

    DOE Data Explorer

    Ferrare, Richard

    2012-12-14

    Planetary Boundary Layer (PBL) heights have been computed using potential temperature profiles derived from Raman lidar and AERI measurements. Raman lidar measurements of the rotational Raman scattering from nitrogen and oxygen are used to derive vertical profiles of potential temperature. AERI measurements of downwelling radiance are used in a physical retrieval approach (Smith et al. 1999, Feltz et al. 1998) to derive profiles of temperature and water vapor. The Raman lidar and AERI potential temperature profiles are merged to create a single potential temperature profile for computing PBL heights. PBL heights were derived from these merged potential temperature profiles using a modified Heffter (1980) technique that was tailored to the SGP site (Della Monache et al., 2004). PBL heights were computed on an hourly basis for the period January 1, 2009 through December 31, 2011. These heights are provided as meters above ground level.

  12. Influence of the vertical absorption profile of mixed Asian dust plumes on aerosol direct radiative forcing over East Asia

    NASA Astrophysics Data System (ADS)

    Noh, Young Min; Lee, Kwonho; Kim, Kwanchul; Shin, Sung-Kyun; Müller, Detlef; Shin, Dong Ho

    2016-08-01

    We estimate the aerosol direct radiative forcing (ADRF) and heating rate profiles of mixed East Asian dust plumes in the solar wavelength region ranging from 0.25 to 4.0 μm using the Santa Barbara Discrete Ordinate Atmospheric Radiative Transfer (SBDART) code. Vertical profiles of aerosol extinction coefficients and single-scattering albedos (SSA) were derived from measurements with a multi-wavelength Raman lidar system. The data are used as input parameters for our radiative transfer calculations. We considered four cases of radiative forcing in SBDART: 1. dust, 2. pollution, 3. mixed dust plume and the use of vertical profiles of SSA, and 4. mixed dust plumes and the use of column-averaged values of SSA. In our sensitivity study we examined the influence of SSA and aerosol layer height on our results. The ADRF at the surface and in the atmosphere shows a small dependence on the specific shape of the aerosol extinction vertical profile and its light-absorption property for all four cases. In contrast, at the top of the atmosphere (TOA), the ADRF is largely affected by the vertical distribution of the aerosols extinction. This effect increases if the light-absorption capacity (decrease of SSA) of the aerosols increases. We find different radiative effects in situations in which two layers of aerosols had different light-absorption properties. The largest difference was observed at the TOA for an absorbing aerosol layer at high altitude in which we considered in one case the vertical profile of SSA and in another case the column-averaged SSA only. The ADRF at the TOA increases when the light-absorbing aerosol layer is located above 3 km altitude. The differences between height-resolved SSA, which can be obtained from lidar data, and total layer-mean SSA indicates that the use of a layer-mean SSA can be rather misleading as it can induce a large error in the calculation of the ADRF at the TOA, which in turn may cause errors in the vertical profiles of heating rates.

  13. Aerosol Property Comparison Within and Above the ABL at the ARM Program SGP Site

    SciTech Connect

    Delle Monache, L

    2002-05-01

    This thesis determines what, if any, measurements of aerosol properties made at the Earth surface are representative of those within the entire air column. Data from the Atmospheric Radiation Measurement site at the Southern Great Plains, the only location in the world where ground-based and in situ airborne measurements are routinely made. Flight legs during the one-year period from March 2000 were categorized as either within or above the atmospheric boundary layer (ABL) by use of an objective mixing height determination technique. Correlations between aerosol properties measured at the surface and those within and above the ABL were computed. Aerosol extensive and intensive properties measured at the surface were found representative of values within the ABL, but not of within the free atmosphere.

  14. Direct radiative forcing and atmospheric absorption by boundary layer aerosols in the southeastern US: model estimates on the basis of new observations

    NASA Astrophysics Data System (ADS)

    Yu, Shaocai; Zender, Charles S.; Saxena, V. K.

    In an effort to reduce uncertainties in the quantification of aerosol direct radiative forcing (ADRF) in the southeastern United States (US), a field column experiment was conducted to measure aerosol radiative properties and effects at Mt. Mitchell, North Carolina, and at an adjacent valley site. The experimental period was from June 1995 to mid-December 1995. The aerosol optical properties (single scattering albedo and asymmetry factor) needed to compute ADRF were obtained on the basis of a procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, aerosol optical depth, and diffuse-to-direct solar irradiance ratio. The regional values of ADRF at the surface and top of atmosphere (TOA), and atmospheric aerosol absorption are derived using the obtained aerosol optical properties as inputs to the column radiation model (CRM) of the community climate model (CCM3). The cloud-free instantaneous TOA ADRFs for highly polluted (HP), marine (M) and continental (C) air masses range from 20.3 to -24.8, 1.3 to -10.4, and 1.9 to -13.4 W m -2, respectively. The mean cloud-free 24-h ADRFs at the TOA (at the surface) for HP, M, and C air masses are estimated to be -8±4 (-33±16), -7±4 (-13±8), and -0.14±0.05 (-8±3) W m -2, respectively. On the assumption that the fractional coverage of clouds is 0.61, the annual mean ADRFs at the TOA and the surface are -2±1, and -7±2 W m -2, respectively. This also implies that aerosols currently heat the atmosphere over the southeastern US by 5±3 W m -2 on annual timescales due to the aerosol absorption in the troposphere.

  15. Boundary layer regulation in the southeast Atlantic cloud microphysics during the biomass burning season as seen by the A-train satellite constellation

    NASA Astrophysics Data System (ADS)

    Painemal, David; Kato, Seiji; Minnis, Patrick

    2014-10-01

    Solar radiation absorption by biomass burning aerosols has a strong warming effect over the southeast Atlantic. Interactions between the overlying smoke aerosols and low-level cloud microphysics and the subsequent albedo perturbation are, however, generally ignored in biomass burning radiative assessments. In this study, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) are combined with Aqua satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Microwave Scanning Radiometer-EOS (AMSR-E), and Clouds and the Earth's Radiant Energy System (CERES) to assess the effect of variations in the boundary layer height and the separation distance between the cloud and aerosol layers on the cloud microphysics. The merged data analyzed at a daily temporal resolution suggest that overlying smoke aerosols modify cloud properties by decreasing cloud droplet size despite an increase in the cloud liquid water as boundary layer deepens, north of 5°S. These changes are controlled by the proximity of the aerosol layer to the cloud top rather than increases in the column aerosol load. The correlations are unlikely driven by meteorological factors, as three predictors of cloud variability, lower tropospheric stability, surface winds, and mixing ratio suggest that cloud effective radius, cloud top height, and liquid water path should correlate positively. Because cloud effective radius anticorrelates with cloud liquid water over the region with large microphysical changes—north of 5°S—the overall radiative consequence at the top of the atmosphere is a strong albedo susceptibility, equivalent to a 3% albedo increase due to a 10% decrease in cloud effective radius. This albedo enhancement partially offsets the aerosol solar absorption. Our analysis emphasizes the importance of accounting for the indirect effect of smoke aerosols in the cloud microphysics when estimating the radiative impact of the biomass burning at the

  16. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  17. Global cloud top height retrieval using SCIAMACHY limb spectra: model studies and first results

    NASA Astrophysics Data System (ADS)

    Eichmann, Kai-Uwe; Lelli, Luca; von Savigny, Christian; Sembhi, Harjinder; Burrows, John P.

    2016-03-01

    observed in limb geometry. Co-located cloud top height measurements of the limb-viewing Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on ENVISAT are compared for the period from January 2008 to March 2012. The global CTH agreement of about 1 km is observed, which is smaller than the vertical field of view of both instruments. Lower stratospheric aerosols from volcanic eruptions occasionally interfere with the cloud retrieval and inhibit the detection of tropospheric clouds. The aerosol impact on cloud retrievals was studied for the volcanoes Kasatochi (August 2008), Sarychev Peak (June 2009), and Nabro (June 2011). Long-lasting aerosol scattering is detected after these events in the Northern Hemisphere for heights above 12.5 km in tropical and polar latitudes. Aerosol top heights up to about 22 km are found in 2009 and the enhanced lower stratospheric aerosol layer persisted for about 7 months. In August 2009 about 82 % of the lower stratosphere between 30 and 70° N was filled with scattering particles and nearly 50 % in October 2008.

  18. Diurnal cycling of urban aerosols under different weather regimes

    NASA Astrophysics Data System (ADS)

    Gregorič, Asta; Drinovec, Luka; Močnik, Griša; Remškar, Maja; Vaupotič, Janja; Stanič, Samo

    2016-04-01

    A one month measurement campaign was performed in summer 2014 in Ljubljana, the capital of Slovenia (population 280,000), aiming to study temporal and spatial distribution of urban aerosols and the mixing state of primary and secondary aerosols. Two background locations were chosen for this purpose, the first one in the city center (urban background - KIS) and the second one in the suburban background (Brezovica). Simultaneous measurements of black carbon (BC) and particle number size distribution of submicron aerosols (PM1) were conducted at both locations. In the summer season emission from traffic related sources is expected to be the main local contribution to BC concentration. Concentrations of aerosol species and gaseous pollutants within the planetary boundary layer are controlled by the balance between emission sources of primary aerosols and gases, production of secondary aerosols, chemical reactions of precursor gases under solar radiation and the rate of dilution by mixing within the planetary boundary layer (PBL) as well as with tropospheric air. Only local emission sources contribute to BC concentration during the stable PBL with low mixing layer height, whereas during the time of fully mixed PBL, regionally transported BC and other aerosols can contribute to the surface measurements. The study describes the diurnal behaviour of the submicron aerosol at the urban and suburban background location under different weather regimes. Particles in three size modes - nucleation (< 25 nm, NUM), Aitken (25 - 90 nm, AIM) and accumulation mode (90 - 800 nm, ACM), as well as BC mass concentration were evaluated separately for sunny, cloudy and rainy days, taking into account modelled values of PBL height. Higher particle number and black carbon concentrations were observed at the urban background (KIS) than at the suburban background location (Brezovica). Significant diurnal pattern of total particle concentration and black carbon concentration was observed at both

  19. Aerosol-cloud interactions in ship tracks using Terra MODIS/MISR

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chun; Christensen, Matthew W.; Diner, David J.; Garay, Michael J.

    2015-04-01

    Simultaneous ship track observations from Terra Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectroradiometer (MISR) have been compiled to investigate how ship-injected aerosols affect marine warm boundary layer clouds for different cloud types and environmental conditions. By taking advantage of the high spatial resolution multiangle observations available from MISR, we utilized the retrieved cloud albedo, cloud top height, and cloud motion vectors to examine cloud property responses in ship-polluted and nearby unpolluted clouds. The strength of the cloud albedo response to increased aerosol level is primarily dependent on cloud cell structure, dryness of the free troposphere, and boundary layer depth, corroborating a previous study by Chen et al. (2012) where A-Train satellite data were utilized. Under open cell cloud structure the cloud properties are more susceptible to aerosol perturbations as compared to closed cells. Aerosol plumes caused an increase in liquid water amount (+38%), cloud top height (+13%), and cloud albedo (+49%) for open cell clouds, whereas for closed cell clouds, little change in cloud properties was observed. Further capitalizing on MISR's unique capabilities, the MISR cross-track cloud speed was used to derive cloud top divergence. Statistically averaging the results from the identified plume segments to reduce random noise, we found evidence of cloud top divergence in the ship-polluted clouds, whereas the nearby unpolluted clouds showed cloud top convergence, providing observational evidence of a change in local mesoscale circulation associated with enhanced aerosols. Furthermore, open cell polluted clouds revealed stronger cloud top divergence as compared to closed cell clouds, consistent with different dynamical mechanisms driving their responses. These results suggest that detailed cloud responses, classified by cloud type and environmental conditions, must be accounted for in global climate modeling

  20. Impact of natural and anthropogenic aerosols on stratocumulus and precipitation in the Southeast Pacific: a regional modelling study using WRF-Chem

    SciTech Connect

    Yang, Q.; Gustafson, W. I.; Fast, J. D.; Wang, H.; Easter, R. C.; Wang, M.; Ghan, S. J.; Berg, L. K.; Leung, L. R.; Morrison, H.

    2012-09-28

    Cloud-system resolving simulations with the chemistry version of the Weather Research and Forecasting (WRF-Chem) model are used to quantify the relative impacts of regional anthropogenic and oceanic emissions on changes in aerosol properties, cloud macro- and microphysics, and cloud radiative forcing over the Southeast Pacific (SEP) during the VAMOS Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx) (15 October–16 November 2008). Two distinct regions are identified. The near-coast polluted region is characterized by low surface precipitation rates, the strong suppression of non-sea-salt particle activation due to sea-salt particles, a predominant albedo effect in aerosol indirect effects, and limited impact of aerosols associated with anthropogenic emissions on clouds. Opposite sensitivities to natural marine and anthropogenic aerosol perturbations are seen in cloud properties (e.g., cloud optical depth and cloud-top and cloud-base heights), precipitation, and the top-of-atmosphere and surface shortwave fluxes over this region. The relatively clean remote region is characterized by large contributions of aerosols from non-regional sources (lateral boundaries) and much stronger drizzle at the surface. Under a scenario of five-fold increase in regional anthropogenic emissions, this relatively clean region shows large cloud responses, for example, a 13% increase in cloud-top height and a 9% increase in albedo in response to a moderate increase (25% of the reference case) in cloud condensation nuclei (CCN) concentration. The reduction of precipitation due to this increase in anthropogenic aerosols more than doubles the aerosol lifetime in the clean marine boundary layer. Therefore, the aerosol impacts on precipitation are amplified by the positive feedback of precipitation on aerosol, which ultimately alters the cloud micro- and macro-physical properties, leading to strong aerosol-cloud-precipitation interactions. The high sensitivity is also related

  1. Tropospheric aerosols: size-differentiated chemistry and large-scale spatial distributions.

    PubMed

    Hidy, George M; Mohnen, Volker; Blanchard, Charles L

    2013-04-01

    Worldwide interest in atmospheric aerosols has emerged since the late 20th century as a part of concerns for air pollution and radiative forcing of the earth's climate. The use of aircraft and balloons for sampling and the use of remote sensing have dramatically expanded knowledge about tropospheric aerosols. Our survey gives an overview of contemporary tropospheric aerosol chemistry based mainly on in situ measurements. It focuses on fine particles less than 1-2.5 microm in diameter. The physical properties of particles by region and altitude are exemplified by particle size distributions, total number and volume concentration, and optical parameters such as extinction coefficient and aerosol optical depth. Particle chemical characterization is size dependent, differentiated by ubiquitous sulfate, and carbon, partially from anthropogenic activity. Large-scale particle distributions extend to intra- and intercontinental proportions involving plumes from population centers to natural disturbances such as dust storms and vegetation fires. In the marine environment, sea salt adds an important component to aerosols. Generally, aerosol components, most of whose sources are at the earth's surface, tend to dilute and decrease in concentration with height, but often show different (layered) profiles depending on meteorological conditions. Key microscopic processes include new particle formation aloft and cloud interactions, both cloud initiation and cloud evaporation. Measurement campaigns aloft are short term, giving snapshots of inherently transient phenomena in the troposphere. Nevertheless, these data, combined with long-term data at the surface and optical depth and transmission observations, yield a unique picture of global tropospheric particle chemistry. PMID:23687724

  2. Assessment of microphysical and chemical factors of aerosols over seas of the Russian Artic Eastern Section

    NASA Astrophysics Data System (ADS)

    Golobokova, Liudmila; Polkin, Victor

    2014-05-01

    The newly observed kickoff of the Northern Route development drew serious attention to state of the Arctic Resource environment. Occurring climatic and environmental changes are more sensitively seen in polar areas in particular. Air environment control allows for making prognostic assessments which are required for planning hazardous environmental impacts preventive actions. In August - September 2013, RV «Professor Khlustin» Northern Sea Route expeditionary voyage took place. En-route aerosol sampling was done over the surface of the Beringov, Chukotka and Eastern-Siberia seas (till the town of Pevek). The purpose of sampling was to assess spatio-temporal variability of optic, microphysical and chemical characteristics of aerosol particles of the surface layer within different areas adjacent to the Northern Sea Route. Aerosol test made use of automated mobile unit consisting of photoelectric particles counter AZ-10, aetalometr MDA-02, aspirator on NBM-1.2 pump chassis, and the impactor. This set of equipment allows for doing measurements of number concentration, dispersed composition of aerosols within sizes d=0.3-10 mkm, mass concentration of submicron sized aerosol, and filter-conveyed aerosols sampling. Filter-conveyed aerosols sampling was done using method accepted by EMEP and EANET monitoring networks. The impactor channel was upgraded to separate particles bigger than 1 mkm in size, and the fine grain fraction settled down on it. Reverse 5-day and 10-day trajectories of air mass transfer executed at heights of 10, 1500 and 3500 m were analyzed. The heights were selected by considerations that 3000 m is the height which characterizes air mass trend in the lower troposphere. 1500 m is the upper border of the atmospheric boundary layer, and the sampling was done in the Earth's surface layer at less than 10 m. Minimum values of the bespoken microphysical characteristics are better characteristic of higher latitudes where there are no man induced sources of

  3. Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

    SciTech Connect

    Saide P. E.; Springston S.; Spak, S. N.; Carmichael, G. R.; Mena-Carrasco, M. A.; Yang, Q.; Howell, S.; Leon, D. C.; Snider, J. R.; Bandy, A. R.; Collett, J. L.; Benedict, K. B.; de Szoeke, S. P.; Hawkins, L. N.; Allen, G.; Crawford, I.; Crosier, J.

    2012-03-29

    We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and three aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign-averaged longitudinal gradients, and highlight differences in model simulations with (W) and without (NW) wet deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, especially in the activation parameterization, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions, and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, and may do so with the reliability required for policy analysis.

  4. Evaluating WRF-Chem aerosol indirect effects in Southeast Pacific marine stratocumulus during VOCALS-REx

    SciTech Connect

    Saide, Pablo; Spak, S. N.; Carmichael, Gregory; Mena-Carrasco, M. A.; Yang, Qing; Howell, S. G.; Leon, Dolislager; Snider, Jefferson R.; Bandy, Alan R.; Collett, Jeffrey L.; Benedict, K. B.; de Szoeke, S.; Hawkins, Lisa; Allen, Grant; Crawford, I.; Crosier, J.; Springston, S. R.

    2012-03-30

    We evaluate a regional-scale simulation with the WRF-Chem model for the VAMOS (Variability of the American Monsoon Systems) Ocean-Cloud-Atmosphere-Land Study Regional Experiment (VOCALS-REx), which sampled the Southeast Pacific's persistent stratocumulus deck. Evaluation of VOCALS-REx ship-based and aircraft observations focuses on analyzing how aerosol loading affects marine boundary layer (MBL) dynamics and cloud microphysics. We compare local time series and campaign averaged longitudinal gradients, and highlight differences in model simulations with (W) and without wet (NW) deposition processes. The higher aerosol loadings in the NW case produce considerable changes in MBL dynamics and cloud microphysics, in accordance with the established conceptual model of aerosol indirect effects. These include increase in cloud albedo, increase in MBL and cloud heights, drizzle suppression, increase in liquid water content, and increase in cloud lifetime. Moreover, better statistical representation of aerosol mass and number concentration improves model fidelity in reproducing observed spatial and temporal variability in cloud properties, including top and base height, droplet concentration, water content, rain rate, optical depth (COD) and liquid water path (LWP). Together, these help to quantify confidence in WRF-Chem's modeled aerosol-cloud interactions, while identifying structural and parametric uncertainties including: irreversibility in rain wet removal; overestimation of marine DMS and sea salt emissions and accelerated aqueous sulfate conversion. Our findings suggest that WRF-Chem simulates marine cloud-aerosol interactions at a level sufficient for applications in forecasting weather and air quality and studying aerosol climate forcing, including the reliability required for policy analysis and geo-engineering applications.

  5. Aerosol characterization at the Saharan AERONET site Tamanrasset

    NASA Astrophysics Data System (ADS)

    Guirado, C.; Cuevas, E.; Cachorro, V. E.; Toledano, C.; Alonso-Pérez, S.; Bustos, J. J.; Basart, S.; Romero, P. M.; Camino, C.; Mimouni, M.; Zeudmi, L.; Goloub, P.; Baldasano, J. M.; de Frutos, A. M.

    2014-06-01

    More than two years of columnar atmospheric aerosol measurements (2006-2009) at Tamanrasset site, in the heart of the Sahara desert, are analysed. AERONET level 2.0 data were used. The KCICLO method was applied to a part of level 1.5 data series to improve the quality of the results. The annual variability of aerosol optical depth (AOD) and Angstrom exponent (AE) has been found to be strongly linked to the Convective Boundary Layer (CBL) thermodynamic features. The dry-cool season (autumn and winter time) is characterized by a shallow CBL and very low mean turbidity (AOD ~ 0.09 at 440 nm, AE ~ 0.62). The wet-hot season (spring and summer time) is dominated by high turbidity of coarse dust particles (AE ~ 0.28, AOD ~ 0.39 at 440 nm) and a deep CBL. The aerosol-type characterization shows desert mineral dust as prevailing aerosol. Both pure Saharan dust and very clear sky conditions are observed depending on the season. However, several case studies indicate an anthropogenic fine mode contribution from Libya and Algeria's industrial areas. The Concentration Weighted Trajectory (CWT) source apportionment method was used to identify potential sources of air masses arriving at Tamanrasset at several heights for each season. Microphysical and optical properties and precipitable water vapour were also investigated.

  6. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog during DRAGON Campaigns in Asia from AERONET and Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Eck, Thomas; Holben, Brent; Reid, Jeffrey; Lynch, Peng; Schafer, Joel; Giles, David; Kim, Jhoon; Kim, Young; Sano, Itaru; Platnick, Steven; Arnold, George; Lyapustin, Alexei; Pickering, Kenneth; Crawford, James; Siniuk, Alexander; Smirnov, Alexander; Wang, Pucai; Xia, Xiangao; Li, Zhanqing

    2015-04-01

    Ground-based remote sensing observations from Aerosol Robotic Network (AERONET) sun-sky radiometers have recently shown several instances where cloud-aerosol interaction had resulted in modification of aerosol properties and/or in difficulty identifying some major pollution transport events due to aerosols being imbedded in cloud systems. AERONET has established Distributed Regional Aerosol Gridded Observation Networks (DRAGON) during field campaigns that are short-term (~2-3 months) relatively dense spatial networks of ~15 to 45 sun and sky scanning photometers. Major DRAGON field campaigns in Japan and South Korea during Spring of 2012 have yielded observations of aerosol transport associated with clouds and/or aerosol properties modification as a result of fog interaction. Analysis of data from the Korean and Japan DRAGON campaigns shows that major fine-mode aerosol transport events are sometimes associated with extensive cloud cover and that cloud-screening of observations often filter out significant pollution aerosol transport events. The Spectral De-convolution Algorithm (SDA) algorithm was utilized to isolate and analyze the fine-mode aerosol optical depth (AOD) signal from AERONET data for these cases of persistent and extensive cloud cover. Satellite retrievals of AOD from MODIS sensors (from both dark target and MAIAC algorithms) were also investigated to assess the issue of detectability of high AOD events associated with high cloud fraction. Cloud properties retrieved from MODIS are also investigated in relation to the AERONET and satellite measurements of AOD. Underestimation of AOD by the Navy Aerosol Analysis and Prediction System (NAAPS) model at very high AOD at sites in China and Korea was observed, especially for observations that are cloud screened by AERONET (L2 data). Additionally, extensive fog that was coincident with aerosol layer height on some days in Korea resulted in large increases in fine mode aerosol radius, with a mode of cloud

  7. Foraminal height measurement techniques

    PubMed Central

    Phan, Kevin; Rao, Prashanth J.

    2015-01-01

    Background One of the proposed advantages of anterior lumbar interbody fusion (ALIF) is restoration of disc height and hence an indirect foraminal height restoration. While this proposed advantage is often quoted in the literature, there are few robust studies demonstrating restoration of foraminal volume. Thus, this study aimed to review the literature and discuss the progression and development of foramen measurement techniques. Methods A review of the literature was performed to identify studies which reported foraminal height and dimensions following fusion surgery in cadaveric models or patients. Results Techniques in prior studies used to quantify foraminal dimensions before and after fusion operations include analysis from plain radiographs, computed tomography (CT) scans and magnetic resonance imaging (MRI) scans. Recent studies have attempted to standardize foraminal dimension measurements with the use of orthogonal software, accelerator-based measurements and the use of multiple images for three-dimensional reconstruction of the foramen volume. Conclusions Consistent results have demonstrated significant increases in foraminal area and height following anterior lumbar interbody distraction, providing evidence that ALIF can indirectly increase foraminal height. Future studies should use standardized measurement approaches such as the Pedicle-to-Pedicle technique with CT or MRI images to determine changes in foraminal dimensions.

  8. Foraminal height measurement techniques

    PubMed Central

    Phan, Kevin; Rao, Prashanth J.

    2015-01-01

    Background One of the proposed advantages of anterior lumbar interbody fusion (ALIF) is restoration of disc height and hence an indirect foraminal height restoration. While this proposed advantage is often quoted in the literature, there are few robust studies demonstrating restoration of foraminal volume. Thus, this study aimed to review the literature and discuss the progression and development of foramen measurement techniques. Methods A review of the literature was performed to identify studies which reported foraminal height and dimensions following fusion surgery in cadaveric models or patients. Results Techniques in prior studies used to quantify foraminal dimensions before and after fusion operations include analysis from plain radiographs, computed tomography (CT) scans and magnetic resonance imaging (MRI) scans. Recent studies have attempted to standardize foraminal dimension measurements with the use of orthogonal software, accelerator-based measurements and the use of multiple images for three-dimensional reconstruction of the foramen volume. Conclusions Consistent results have demonstrated significant increases in foraminal area and height following anterior lumbar interbody distraction, providing evidence that ALIF can indirectly increase foraminal height. Future studies should use standardized measurement approaches such as the Pedicle-to-Pedicle technique with CT or MRI images to determine changes in foraminal dimensions. PMID:27683677

  9. Aerosol in the Pacific troposphere

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.

    1989-01-01

    The use of near real-time optical techniques is emphasized for the measurement of mid-tropospheric aerosol over the Central Pacific. The primary focus is on measurement of the aerosol size distribution over the range of particle diameters from 0.15 to 5.0 microns that are essential for modeling CO2 backscatter values in support of the laser atmospheric wind sounder (LAWS) program. The measurement system employs a LAS-X (Laser Aerosol Spectrometer-PMS, Boulder, CO) with a custom 256 channel pulse height analyzer and software for detailed measurement and analysis of aerosol size distributions. A thermal preheater system (Thermo Optic Aerosol Descriminator (TOAD) conditions the aerosol in a manner that allows the discrimination of the size distribution of individual aerosol components such as sulfuric acid, sulfates and refractory species. This allows assessment of the relative contribution of each component to the BCO2 signal. This is necessary since the different components have different sources, exhibit independent variability and provide different BCO2 signals for a given mass and particle size. Field activities involve experiments designed to examine both temporal and spatial variability of these aerosol components from ground based and aircraft platforms.

  10. Global cloud top height retrieval using SCIAMACHY limb spectra: model studies and first results

    NASA Astrophysics Data System (ADS)

    Eichmann, K.-U.; Lelli, L.; von Savigny, C.; Sembhi, H.; Burrows, J. P.

    2015-08-01

    Atmospheric Sounding (MIPAS) on ENVISAT for the period from January 2008 to March 2012 were compared, showing good agreement to within 1 km, which is smaller than the vertical field of view of both instruments. Lower stratospheric aerosols from volcanic eruptions occasionally interfered with the cloud retrieval and inhibited detection of tropospheric clouds. Examples of the impact of these events are shown for the volcanoes Kasatochi in August 2008, Sarychev Peak in June 2009, and Nabro in June 2010. Long-lasting aerosol layers were detected after these events in the Northern Hemisphere down to the tropics. Particle top heights up to about 22 km were retrieved in 2009, when the enhanced lower stratospheric aerosol layer persisted for about 7 months. Up to about 82 % of the Northern hemispheric lower stratosphere between 30° and 70° was covered by scattering particles in August 2009 and nearly half in October 2008.

  11. Height unification using GOCE

    NASA Astrophysics Data System (ADS)

    Rummel, R.

    2012-12-01

    With the gravity field and steady-state ocean circulation explorer (GOCE) (preferably combined with the gravity field and climate experiment (GRACE)) a new generation of geoid models will become available for use in height determination. These models will be globally consistent, accurate (<3 cm) and with a spatial resolution up to degree and order 200, when expressed in terms of a spherical harmonic expansion. GOCE is a mission of the European Space Agency (ESA). It is the first satellite equipped with a gravitational gradiometer, in the case of GOCE it measures the gradient components Vxx , Vyy, Vzzand Vxz. The GOCE gravitational sensor system comprises also a geodetic global positioning system (GPS)-receiver, three star sensors and ion-thrusters for drag compensation in flight direction. GOCE was launched in March 2009 and will fly till the end of 2013. Several gravity models have been derived from its data, their maximum degree is typically between 240 and 250. In summer 2012 a first re-processing of all level-1b data took place. One of the science objectives of GOCE is the unification of height systems. The existing height offsets among the datum zones can be determined by least-squares adjustment. This requires several precise geodetic reference points available in each height datum zone, physical heights from spirit levelling (plus gravimetry), the GOCE geoid and, in addition, short wavelength geoid refinement from terrestrial gravity anomalies. GOCE allows for important simplifications of the functional and stochastic part of the adjustment model. The future trend will be the direct determination of physical heights (orthometric as well as normal) from precise global navigation satellite system (GNSS)-positioning in combination with a next generation combined satellite-terrestrial high-resolution geoid model.

  12. Balloon measurements of aerosol in the Antarctic stratosphere

    NASA Technical Reports Server (NTRS)

    Morita, Y.; Takagi, M.; Iwasaka, Y.; Ono, A.

    1985-01-01

    Three balloon soundings of aerosol were conducted from Syowa Station, Antarctica in April, June and October 1983. Number concentration and the size distribution of aerosol particles with diameter greater than 0.3 microns were measured by using a light scattering aerosol particle counter. The influence of the eruption of Mt. El Chichon on the aerosol concentration in the stratosphere was observed on October 16. Very high aerosol concentration at stratospheric heights was obtained from the first successful aerosol sounding in winter Antarctic stratosphere. The result gives direct evidence of winter enhancement in the Antarctic stratosphere.

  13. CALIOP-derived Smoke Plume Injection Height

    NASA Astrophysics Data System (ADS)

    Soja, A. J.; Winker, D. M.; Choi, H. D.; Fairlie, T. D.; Westberg, D. J.; Roller, C. M.; Pouliot, G.; Vaughan, M.; Pierce, T. E.; Trepte, C. R.; Rao, V.

    2014-12-01

    Biomass burning is a dominant natural and anthropogenic disturbance that feeds back to the climate system. Fire regimes, ecosystem fuels, fire severity and intensity vary widely, even within the same system, largely under the control of weather and climate. These strongly influence fire plume injection height and thus the transport of related biomass burning emissions, affecting air quality, human health and the climate system. If our knowledge of plume injection height is incorrect, transport models of those emissions will likewise be incorrect, adversely affecting our ability to analyze and predict climate feedbacks (i.e. black carbon to the Arctic, precipitation, cloud-radiation relationships) and public health (air quality forecast). Historically, plume height was based on the pioneering work of G.A. Briggs [1969; 1971] and verified with limited field campaigns. However, we currently have two satellite instruments, Cloud-Aerosol LIdar with Orthogonal Polarization (CALIOP) onboard CALIPSO (afternoon overpass) and Multi-angle Imaging SpectroRadiometer (MISR) onboard TERRA (morning overpass), that can provide the statistics necessary to verify our assumptions and improve fire plume injection height estimates for use in both small- and large-scale models. We have developed a methodology to assess fire plume injection height using the Langley Trajectory Model (LaTM), CALIOP, Hazard Mapping System (HMS) smoke plume, and MODerate Resolution Imaging Spectrometer (MODIS) thermal anomaly data that is capable of generating two distinct types of verification data. A single CALIOP smoke-filled aerosol envelop can be traced back to numerous fire events, and using multiple CALIOP transects from numerous days, a daily smoke plume injection height evolution from a single fire can be defined. Additionally, we have linked the smoke plumes to ecosystems and the meteorological variables that define fire weather. In concert, CALIOP and MISR data can produce the statistical knowledge

  14. Indian aerosols: present status.

    PubMed

    Mitra, A P; Sharma, C

    2002-12-01

    This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions. PMID:12492171

  15. Indian aerosols: present status.

    PubMed

    Mitra, A P; Sharma, C

    2002-12-01

    This article presents the status of aerosols in India based on the research activities undertaken during last few decades in this region. Programs, like International Geophysical Year (IGY), Monsoon Experiment (MONEX), Indian Middle Atmospheric Program (IMAP) and recently conducted Indian Ocean Experiment (INDOEX), have thrown new lights on the role of aerosols in global change. INDOEX has proved that the effects of aerosols are no longer confined to the local levels but extend at regional as well as global scales due to occurrence of long range transportation of aerosols from source regions along with wind trajectories. The loading of aerosols in the atmosphere is on rising due to energy intensive activities for developmental processes and other anthropogenic activities. One of the significant observation of INDOEX is the presence of high concentrations of carbonaceous aerosols in the near persistent winter time haze layer over tropical Indian Ocean which have probably been emitted from the burning of fossil-fuels and biofuels in the source region. These have significant bearing on the radiative forcing in the region and, therefore, have potential to alter monsoon and hydrological cycles. In general, the SPM concentrations have been found to be on higher sides in ambient atmosphere in many Indian cities but the NOx concentrations have been found to be on lower side. Even in the haze layer over Indian Ocean and surrounding areas, the NOx concentrations have been reported to be low which is not conducive of O3 formation in the haze/smog layer. The acid rain problem does not seem to exist at the moment in India because of the presence of neutralizing soil dust in the atmosphere. But the high particulate concentrations in most of the cities' atmosphere in India are of concern as it can cause deteriorated health conditions.

  16. PULSE HEIGHT ANALYZER

    DOEpatents

    Goldsworthy, W.W.

    1958-06-01

    A differential pulse-height discriminator circuit is described which is readily adaptable for operation in a single-channel pulse-height analyzer. The novel aspect of the circuit lies in the specific arrangement of differential pulse-height discriminator which includes two pulse-height discriminators having a comnnon input and an anticoincidence circuit having two interconnected vacuum tubes with a common cathode resistor. Pulses from the output of one discriminator circuit are delayed and coupled to the grid of one of the anticoincidence tubes by a resistor. The output pulses from the other discriminator circuit are coupled through a cathode follower circuit, which has a cathode resistor of such value as to provide a long time constant with the interelectrode capacitance of the tube, to lenthen the output pulses. The pulses are then fed to the grid of the other anticoincidence tube. With such connections of the circuits, only when the incoming pulse has a pesk value between the operating levels of the two discriminators does an output pulse occur from the anticoincidence circuit.

  17. Exposure of acid aerosol for schoolchildren in metropolitan Taipei

    NASA Astrophysics Data System (ADS)

    Mao, I.-Fang; Lin, Chih-Hung; Lin, Chun-Ji; Chen, Yi-Ju; Sung, Fung-Chang; Chen, Mei-Lien

    Metropolitan Taipei, which is located in the subtropical area, is characterized by high population and automobile densities. For convenience, most primary schools are located near major roads. This study explores the exposure of acid aerosols for schoolchildren in areas in Taipei with different traffic densities. Acid aerosols were collected by using a honeycomb denuder filter pack sampling system (HDS). Experimental results indicated that the air pollutants were significantly correlated with traffic densities. The ambient air NO 2, SO 2, HNO 3, NO 3-, SO 42-, and aerosol acidity concentrations were 31.3 ppb, 4.7 ppb, 1.3 ppb, 1.9 μg m -3, 18.5 μg m -3, and 49.5 nmol m -3 in high traffic density areas, and 6.1 ppb, 1.8 ppb, 0.9 ppb, 0.7 μg m -3, 8.8 μg m -3 and 14.7 nmol m -3 in low traffic density areas. The exposure levels of acid aerosols for schoolchildren would be higher than the measurements because the sampling height was 5 m above the ground. The SO 2 levels were low (0.13-8.03 ppb) in the metropolitan Taipei. However, the SO 42- concentrations were relatively high, and might be attributed to natural emissions of sulfur-rich geothermal sources. The seasonal variations of acid aerosol concentrations were also observed. The high levels of acidic particles in spring time may be attributed to the Asian dust storm and low height of the mixture layer. We conclude that automobile contributed not only the primary pollutants but also the secondary acid aerosols through the photochemical reaction. Schoolchildren were exposed to twice the acid aerosol concentrations in high traffic density areas compared to those in low traffic density areas. The incidence of allergic rhinitis of schoolchildren in the high traffic density areas was the highest in spring time. Accompanied by high temperature variation and high levels of air pollution in spring, the health risk of schoolchildren had been observed.

  18. A new method for assessing the aerosol to rain chemical composition relationships

    NASA Astrophysics Data System (ADS)

    Bourcier, L.; Masson, O.; Laj, P.; Chausse, P.; Pichon, J. M.; Paulat, P.; Bertrand, G.; Sellegri, K.

    2012-11-01

    Measurements were conducted at three sampling sites located at different altitudes in the centre of France during two years, both in the rain and aerosol phases. The rain was sampled at a boundary layer site while the aerosol particles were collected at two different altitudes, which allow a better characterization of the vertical atmospheric column being washed out. Various chemical analyses were performed to characterize reactive (NO3-, SO42-, NH4+ and K+) and inert (7Be, 210Pb and 137Cs) species transfer from the aerosol to the rain phase. This set-up was ideal to calculate the washout ratio (WR) using different concentrations of the aerosol phase. Using the classical WR calculated with the aerosol concentration sampled at the same altitude than the rain collectors, we observed a seasonality of WR, with higher value in winter and lower value in summer for radionuclides. At the higher altitude site, local contaminations do not influence the aerosol concentration, which then should be representative of the whole atmospheric column. The annual variability is high at this site maybe because aerosol concentrations can be less concentrated than the whole atmospheric column when this later one is not well mixed. In order to increase the reliability of the WR, we propose a new method for calculating washout ratio from measurements at the rain collector level. This new calculation takes into account the height of the boundary layer, we observed that it decreased the variability of the washout ratio (for 7Be, 210Pb and NO3-), with less dependence to the season.

  19. Analysis of the Interaction and Transport of Aerosols with Cloud or Fog during Dragon Campaigns from Aeronet and Satellite Remote Sensing

    NASA Astrophysics Data System (ADS)

    Eck, T. F.;