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Sample records for aerosol index aai

  1. Can an active aging index (AAI) provide insight into reducing elder abuse? A case study in Rajshahi District, Bangladesh.

    PubMed

    Tareque, Md Ismail; Ahmed, Md Munsur; Tiedt, Andrew D; Hoque, Nazrul

    2014-01-01

    We use data from respondents aged 60 years and above, collected during April 2009 in the Rajshahi district of Bangladesh, to examine whether high activeness, as captured by an AAI or in sub-domains, can help reduce the risk of elder abuse. The findings suggest that more than half of rural elderly and 14 percent of urban elderly were at some point abused. High activeness in health and security dimensions lowers the risk of being abused while those who are low active in community participation have the lowest risk of being abused in both rural and urban areas. Being literate (elderly with primary/secondary education) is revealed to be a significant factor that lowers the risk of abuse in both rural and urban areas. These results imply a need for educational programs that bolster positive and proper community interaction, in turn promoting a secure later life for elders, and reducing burden for families and society. High activeness in health and security dimensions should also be promoted to keep the elderly healthy and protect from abusive behavior.

  2. Aerosol Index Dynamics over Athens and Beijing

    NASA Astrophysics Data System (ADS)

    Christodoulakis, J.; Varotsos, C.; Tzanis, C.; Xue, Y.

    2014-11-01

    We present the analysis of monthly mean Aerosol Index (AI) values, over Athens, Greece, and Beijing, China, for the period 1979-2012. The aim of the analysis is the identification of time scaling in the AI time series, by using a data analysis technique that would not be affected by the non-stationarity of the data. The appropriate technique satisfying this criterion is the Detrended Fluctuation Analysis (DF A). For the deseasonalization of time series classic Wiener method was applied filtering out the seasonal - 3 months, semiannual - 6 months and annual - 12 months periods. The data analysis for both Athens and Beijing revealed that the exponents α for both time periods are greater than 0.5 indicating that persistence of the correlations in the fluctuations of the deseasonalized AI values exists for time scales between about 4 months and 3.5 years (for the period 1979-1993) or 4 years (for the period 1996-2012).

  3. Aerosol Index Dynamics over Athens and Beijing

    NASA Astrophysics Data System (ADS)

    Christodoulakis, J.; Varotsos, C.; Tzanis, C.; Xue, Y.

    2014-11-01

    We present the analysis of monthly mean Aerosol Index (AI) values, over Athens, Greece, and Beijing, China, for the period 1979- 2012. The aim of the analysis is the identification of time scaling in the AI time series, by using a data analysis technique that would not be affected by the non-stationarity of the data. The appropriate technique satisfying this criterion is the Detrended Fluctuation Analysis (DFA). For the deseasonalization of time series classic Wiener method was applied filtering out the seasonal - 3 months, semiannual - 6 months and annual - 12 months periods. The data analysis for both Athens and Beijing revealed that the exponents α for both time periods are greater than 0.5 indicating that persistence of the correlations in the fluctuations of the deseasonalized AI values exists for time scales between about 4 months and 3.5 years (for the period 1979-1993) or 4 years (for the period 1996-2012).

  4. 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.

  5. 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., Jr.; Colarco, P. R.; Darmenov, A.; Govindaraju, R.

    2014-12-01

    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 derived from the Ozone Monitoring Instrument (OMI) measurements as independent validation for the Modern Era Retrospective analysis for Research and Applications Aerosol Reanalysis (MERRAero). In this presentation we show comparisons of model produced AI with the corresponding OMI measurements during several months of 2007 characterized by a good sampling of dust and biomass burning events. In parallel, model produced Absorption Aerosol Optical Depth (AAOD) were compared to OMI AAOD for the same period, identifying regions where the model representation of absorbing aerosols were deficient. 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) and the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors, 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 misplacement of plume height by the model.

  6. 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.

    2014-12-01

    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 South 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

  7. 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

  8. Aerosol penetration ratio: a new index of ventilation

    SciTech Connect

    Sirr, S.A.; Elliott, G.R.; Regelmann, W.E.; Juenemann, P.J.; Morin, R.L.; Boudreau, R.J.; Warwick, W.J.; Loken, M.K.

    1986-08-01

    Superimposition of nuclear medicine scintigrams and standard radiographs provides a unique opportunity for merging functional information intrinsic to nuclear medicine images with the high resolution anatomic detail of radiographs. A newly developed image processing system allows the merging of two separate films of greatly varying sizes to form a single composite image. Subsequent quantitative analysis of the composite image may be performed. Using the superimposition technique, (/sup 99m/Tc)DTPA aerosol ventilation scans (4.5 X 4.5 cm) were superimposed upon chest radiographs (35.6 X 43.2 cm) in 17 cystic fibrosis (CF) patients. Subsequent quantification of the area of nuclear scan ventilation and the radiographic lung area was then performed. A new quantitative radiologic index of ventilation, the aerosol penetration ratio (APR), was defined. Linear correlation of aerosol penetration ratio with residual volume (RV) as percent of total lung capacity (TLC) measured by body plethysmography was good. We conclude that the APR has validity as a physiologic parameter which localized regional excessive residual volume and correlates well with RV/TLC, the gold standard pulmonary function index of obstructive airway disease.

  9. Applications of UV Scattering and Absorbing Aerosol Indices

    NASA Astrophysics Data System (ADS)

    Penning de Vries, M.; Beirle, S.; Wagner, T.

    2009-04-01

    Aerosols cause a substantial amount of radiative forcing, but quantifying this amount is difficult: determining aerosol concentrations in the atmosphere and, especially, characterizing their (optical) properties, has proved to be quite a challenge. A good way to monitor aerosol characteristics on a global scale is to perform satellite remote sensing. Most satellite aerosol retrieval algorithms are based on fitting of aerosol-induced changes in earth reflectance, which are usually subtle and have a smooth wavelength dependence. In such algorithms certain aerosol models are assumed, where optical parameters such as single scattering albedo, asymmetry parameter and size parameter (or Angstrom exponent) are defined. Another, semi-quantitative technique for detecting aerosols is the calculation of UV Aerosol Indices (UVAI). The Absorbing and Scattering Aerosol Indices detect "UV-absorbing" aerosols (most notably mineral dust, black and brown carbon particles) and "scattering" aerosols (sulfate and secondary organic aerosol particles), respectively. UVAI are essentially a measure of the contrast between two wavelengths in the UV range. The advantages of UVAI are: they can be determined in the presence of clouds, they are rather insensitive to surface type, and they are very sensitive to aerosols. The Absorbing Aerosol Index (AAI) has been in use for over a decade, and the Scattering Aerosol Index (SAI) was recently introduced by our group. Whereas the AAI is mainly used to detect desert dust and biomass burning plumes, the SAI can be used to study regions with high concentrations of non-absorbing aerosols, either anthropogenic (e.g. sulfate aerosols in eastern China) or biogenic (e.g. secondary organic aerosols formed from VOCs emitted by plants). Here we will present our recent UVAI results from SCIAMACHY: we will discuss the seasonal trend of SAI, and correlate our UVAI data with other datasets such as trace gases (HCHO, NO2, CO) and fire counts from the (A

  10. 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.

  11. Simulations of the Aerosol Index and the Absorption Aerosol Optical Depth and Comparisons with OMI Retrievals During ARCTAS-2008 Campaign

    NASA Technical Reports Server (NTRS)

    2010-01-01

    We have computed the Aerosol Index (AI) at 354 nm, useful for observing the presence of absorbing aerosols in the atmosphere, from aerosol simulations conducted with the Goddard Chemistry, Aerosol, Radiation, and Transport (GOCART) module running online the GEOS-5 Atmospheric GCM. The model simulates five aerosol types: dust, sea salt, black carbon, organic carbon and sulfate aerosol and can be run in replay or data assimilation modes. In the assimilation mode, information's provided by the space-based MODIS and MISR sensors constrains the model aerosol state. Aerosol optical properties are then derived from the simulated mass concentration and the Al is determined at the OMI footprint using the radiative transfer code VLIDORT. In parallel, model derived Absorption Aerosol Optical Depth (AAOD) is compared with OMI retrievals. We have focused our study during ARCTAS (June - July 2008), a period with a good sampling of dust and biomass burning events. Our ultimate goal is to use OMI measurements as independent validation for our MODIS/MISR assimilation. Towards this goal we document the limitation of OMI aerosol absorption measurements on a global scale, in particular sensitivity to aerosol vertical profile and cloud contamination effects, deriving the appropriate averaging kernels. More specifically, model simulated (full) column integrated AAOD is compared with model derived Al, this way identifying those regions and conditions under which OMI cannot detect absorbing aerosols. Making use of ATrain cloud measurements from MODIS, C1oudSat and CALIPSO we also investigate the global impact on clouds on OMI derived Al, and the extent to which GEOS-5 clouds can offer a first order representation of these effects.

  12. Aerosol Climate Time Series Evaluation In ESA Aerosol_cci

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Retrieval of UV Aerosol Index using backscattered monochromatic radiance measured by GOSAT CAI

    NASA Astrophysics Data System (ADS)

    Go, S.; Kim, J.; KIM, M.; Park, S. S.

    2014-12-01

    UV Aerosol Index(AI) using backscattered radiance at a single channel has been retrieved. In the current UV AI algorithm, two UV channels are used to contrast the absorbing aerosol loaded atmosphere to Rayleigh scattering condition. There have been needs to retrieve information of absorbing aerosol from a single UV channel, such as GOSAT CAI. 30-day minimum composite method, however, makes the process possible to construct the condition with the use of only single UV channel. Also, absorption by aerosol changes with respect to AOD and wavelength for different aerosol types. Therefore, single channel aerosol index(SAI) can detect absorbing aerosol qualitatively. Correlation coefficient of SAI to current UV AI indicate significant value, showing possibility of detecting highly absorbing aerosols. The application of a cloud screening makes the presence of absorbing aerosols even more clear. Radiative transfer calculations using VLIDORT were performed to test the sensitivity of SAI and UV AI to aerosol optical properties, showing that highly absorbing aerosol results in meaningful SAI. Results from dust case study in East Asia show reasonable performance of SAI for the region with single scattering albedo below 0.90. This study concludes with a comparison of SAI from GOSAT lv.1b data to OMI UVAI data, where reasonable agreement and low false detection was found for dust cases in East Asia. The SAI value of -0.2 to 0.0 from GOSAT-CAI was comparable to OMI dust threshold value of 0.7. These findings corroborate the suitability of SAI as a for detecting absorbing aerosols for satellite instrument with a single UV channel.

  14. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.; Ferrare, R. A.; Browell, E. V.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the "effective" aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar-derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  15. Retrieving the Vertical Structure of the Effective Aerosol Complex Index of Refraction from a Combination of Aerosol in Situ and Remote Sensing Measurements During TARFOX

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Turco, R. P.; Liou, K. N.; Russell, P. B.; Bergstrom, R. W.; Schmid, B.; Livingston, J. M.; Hobbs, P. V.; Hartley, W. S.; Ismail, S.

    2000-01-01

    The largest uncertainty in estimates of the effects of atmospheric aerosols on climate stems from uncertainties in the determination of their microphysical properties, including the aerosol complex index of refraction, which in turn determines their optical properties. A novel technique is used to estimate the aerosol complex index of refraction in distinct vertical layers from a combination of aerosol in situ size distribution and remote sensing measurements during the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX). In particular, aerosol backscatter measurements using the NASA Langley LASE (Lidar Atmospheric Sensing Experiment) instrument and in situ aerosol size distribution data are utilized to derive vertical profiles of the 'effective' aerosol complex index of refraction at 815 nm (i.e., the refractive index that would provide the same backscatter signal in a forward calculation on the basis of the measured in situ particle size distributions for homogeneous, spherical aerosols). A sensitivity study shows that this method yields small errors in the retrieved aerosol refractive indices, provided the errors in the lidar derived aerosol backscatter are less than 30% and random in nature. Absolute errors in the estimated aerosol refractive indices are generally less than 0.04 for the real part and can be as much as 0.042 for the imaginary part in the case of a 30% error in the lidar-derived aerosol backscatter. The measurements of aerosol optical depth from the NASA Ames Airborne Tracking Sunphotometer (AATS-6) are successfully incorporated into the new technique and help constrain the retrieved aerosol refractive indices. An application of the technique to two TARFOX case studies yields the occurrence of vertical layers of distinct aerosol refractive indices. Values of the estimated complex aerosol refractive index range from 1.33 to 1.45 for the real part and 0.001 to 0.008 for the imaginary part. The methodology devised in this study

  16. Stratospheric aerosol acidity, density, and refractive index deduced from SAGE 2 and NMC temperature data

    NASA Technical Reports Server (NTRS)

    Yue, G. K.; Poole, L. R.; Wang, P.-H.; Chiou, E. W.

    1994-01-01

    Water vapor concentrations obtained by the Stratospheric Aerosol and Gas Experiment 2 (SAGE 2) and collocated temperatures provided by the National Meteorological Center (NMC) from 1986 to 1990 are used to deduce seasonally and zonally averaged acidity, density, and refractive index of stratospheric aerosols. It is found that the weight percentage of sulfuric acid in the aerosols increases from about 60 just above the tropopause to about 86 at 35 km. The density increases from about 1.55 to 1.85 g/cu cm between the same altitude limits. Some seasonal variations of composition and density are evident at high latitudes. The refractive indices at 1.02, 0.694, and 0.532 micrometers increase, respectively, from about 1.425, 1.430, and 1.435 just above the tropopause to about 1.445, 1.455, and 1.458 at altitudes above 27 km, depending on the season and latitude. The aerosol properties presented can be used in models to study the effectiveness of heterogeneous chemistry, the mass loading of stratospheric aerosols, and the extinction and backscatter of aerosols at different wavelengths. Computed aerosol surface areas, rate coefficients for the heterogeneous reaction ClONO2 + H2O yields HOCl + HNO3 and aerosol mass concentrations before and after the Pinatubo eruption in June 1991 are shown as sample applications.

  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. Climatological analysis of aerosol optical properties over East Africa observed from space-borne sensors during 2001-2015

    NASA Astrophysics Data System (ADS)

    Boiyo, Richard; Kumar, K. Raghavendra; Zhao, Tianliang; Bao, Yansong

    2017-03-01

    The present study is aimed at analyzing spatial and temporal characteristics of aerosols retrieved from MODerate resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI) sensors over East Africa (EA). Data spanning for a period of 15 years during 2001-2015 was used to investigate aerosol optical depth (AOD550), Ångstrom exponent (AE470-660) and absorption aerosol Index (AAI) over EA and selected locations within EA. Validation results of MODIS-Terra versus the Aerosol Robotic NETwork (AERONET) AOD550 revealed that the former underestimated aerosol loading over the studied regions due to uncertainties in surface reflectance. The annual mean AOD550, AAI, and AE470-660 were found to be 0.20 ± 0.01, 0.81 ± 0.03, and 1.39 ± 0.01, respectively with peak values observed during the local dry seasons. The spatial seasonal distributions of mean AOD550 suggested high (low) values during the local dry (wet) periods. The high AOD values found along the borders of southwest of Uganda were attributed to smoke particles; while higher (lower) values of AE470-660 (AAI) dominated most parts of the study domain. Low AOD (0.1-0.2) centers were located in high-altitude regions with relatively high vegetation cover over western and central parts of Kenya, and central and northern parts of Tanzania. Furthermore, latitudinal and longitudinal gradients in AOD550 showed a "southern low and northern high" and a "western low and eastern high" profile, respectively during JJA, as other seasons showed heterogeneous variations. Trend analysis revealed a general increase in AOD and AAI and a decrease in AE; while impact factors significantly affected AOD distribution over EA. HYSPLIT back trajectory analyses revealed diverse transport pathways originated from the Arabian Deserts, central Africa, and southwest of Indian Ocean along with locally produced aerosols during different seasons.

  19. Measurement of total lung aerosol deposition as an index of lung abnormality.

    PubMed

    Kim, C S; Lewars, G A; Sackner, M A

    1988-04-01

    Total aerosol deposition in the lung was measured in 100 subjects with various lung conditions. The subjects consisted of 40 normals (N), 15 asymptomatic smokers (S), 10 smokers with small airway disease (SAD), 20 with chronic simple bronchitis (SB), and 15 with chronic obstructive bronchitis (COPD), and a relationship of total aerosol deposition to degree of lung abnormality was investigated. The subjects were categorized by medical history and a battery of pulmonary function tests, including spirometry, body plethysmography, and single and multiple N2 washout measurements. Subjects repeatedly breathed a monodisperse test aerosol (1.0 micron diam) from a collapsible rebreathing bag (0.5 liter volume) at a rate of 30 breaths/min, while inhaled and exhaled aerosol concentrations were continuously monitored by a laser aerosol photometer in situ and recorded on a strip-chart recorder. The number of rebreathing breaths resulting in 90% aerosol loss from the bag (N90) was determined, and percent predicted N90 values were then determined from the results of computer simulation and used as a deposition index. The percent predicted N90 values were 99.7 +/- 14, 86.5 +/- 15, 66.9 +/- 17, 51 +/- 12, and 30.9 +/- 9, respectively, for N, S, SAD, SB, and COPD. All of these values were significantly different from each other (P less than 0.05). There was no difference between male and female but percent predicted N90 values were slightly higher in young than in old normals. Percent predicted N90 values showed a strong linear correlation with spirometric measurements of forced expiratory volume in 1 s and maximum midexpiratory flow rate. However, many of the SAD and SB with normal spirometry showed abnormal N90. These results suggest that total lung aerosol deposition is a sensitive index of lung abnormality and may be of potential use for nonspecific general patient screening.

  20. Adverse Childhood Experiences (ACEs) questionnaire and Adult Attachment Interview (AAI): implications for parent child relationships.

    PubMed

    Murphy, Anne; Steele, Miriam; Dube, Shanta Rishi; Bate, Jordan; Bonuck, Karen; Meissner, Paul; Goldman, Hannah; Steele, Howard

    2014-02-01

    Although Adverse Childhood Experiences (ACEs) are linked to increased health problems and risk behaviors in adulthood, there are no studies on the association between ACEs and adults' states of mind regarding their early childhood attachments, loss, and trauma experiences. To validate the ACEs questions, we analyzed the association between ACEs and emotional support indicators and Adult Attachment Interview (AAI) classifications in terms of unresolved mourning regarding past loss or trauma and discordant states of mind in cannot classify (U/CC) interviews. Seventy-five urban women (41 clinical and 34 community) completed a questionnaire on ACEs, which included 10 categories of abuse, neglect, and household dysfunction, in addition to emotional support. Internal psychological processes or states of mind concerning attachment were assessed using the AAI. ACE responses were internally consistent (Cronbach's α=.88). In the clinical sample, 84% reported≥4 ACEs compared to 27% among the community sample. AAIs judged U/CC occurred in 76% of the clinical sample compared to 9% in the community sample. When ACEs were≥4, 65% of AAIs were classified U/CC. Absence of emotional support in the ACEs questionnaire was associated with 72% of AAIs being classified U/CC. As the number of ACEs and the lack of emotional support increases so too does the probability of AAIs being classified as U/CC. Findings provide rationale for including ACEs questions in pediatric screening protocols to identify and offer treatment reducing the intergenerational transmission of risk associated with problematic parenting.

  1. Atmospheric correction of ocean color imagery: use of the junge power-law aerosol size distribution with variable refractive index to handle aerosol absorption.

    PubMed

    Chomko, R M; Gordon, H R

    1998-08-20

    When strongly absorbing aerosols are present in the atmosphere, the usual two-step procedure of processing ocean color data-(1) atmospheric correction to provide the water-leaving reflectance (rho(w)), followed by (2) relating rho(w) to the water constituents-fails and simultaneous estimation of the ocean and aerosol optical properties is necessary. We explore the efficacy of using a simple model of the aerosol-a Junge power-law size distribution consisting of homogeneous spheres with arbitrary refractive index-in a nonlinear optimization procedure for estimating the relevant oceanic and atmospheric parameters for case 1 waters. Using simulated test data generated from more realistic aerosol size distributions (sums of log-normally distributed components with different compositions), we show that the ocean's pigment concentration (C) can be retrieved with good accuracy in the presence of weakly or strongly absorbing aerosols. However, because of significant differences in the scattering phase functions for the test and power-law distributions, large error is possible in the estimate of the aerosol optical thickness. The positive result for C suggests that the detailed shape of the aerosol-scattering phase function is not relevant to the atmospheric correction of ocean color sensors. The relevant parameters are the aerosol single-scattering albedo and the spectral variation of the aerosol optical depth. We argue that the assumption of aerosol sphericity should not restrict the validity of the algorithm and suggest an avenue for including colored aerosols, e.g., wind-blown dust, in the procedure. A significant advantage of the new approach is that realistic multicomponent aerosol models are not required for the retrieval of C.

  2. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2008-02-01

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

  5. Calculation of aerosol optical properties under different assumptions on mixing state, refractive index, density and hygroscopicity: uncertainties and importance of representation of aerosol mixing state

    NASA Astrophysics Data System (ADS)

    Curci, Gabriele

    2015-04-01

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. We used the FlexAOD post-processing tool to calculate the optical properties (aerosol optical depth (AOD), single scattering albedo (SSA) and asymmetry parameter (g)) from chemistry-transport model aerosol profiles, using a wide range of assumptions on aerosol chemical and physical properties. We calculated that the most important factor of uncertainty is the assumption about the mixing state, for which we estimate an uncertainty of 30-35% on the simulated aerosol optical depth (AOD) and single scattering albedo (SSA). The choice of the core composition in the core-shell representation is of minor importance for calculation of AOD, while it is critical for the SSA. Other factors of uncertainty tested here have a maximum average impact of 10% each on calculated AOD, and an impact of a few percent on SSA and g. We then tested simple parameterizations of the aerosol mixing state, expressed as a function of the aerosol aging, and verified that they may be helpful in reducing the uncertainty when comparing simulations with AERONET retrievals.

  6. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  7. A study on the temporal and spatial variability of absorbing aerosols using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument Aerosol Index data

    NASA Astrophysics Data System (ADS)

    Li, Jing; Carlson, Barbara E.; Lacis, Andrew A.

    2009-05-01

    Absorbing aerosols, especially mineral dust and black carbon, play key roles in climate change by absorbing solar radiation, heating the atmosphere, and contributing to global warming. In this paper, we first examine the consistency of the Aerosol Index (AI) product as measured by the Total Ozone Mapping Spectrometer (TOMS) and Ozone Monitoring Instrument (OMI) instruments and then analyze these AI data sets to investigate the temporal and spatial variability of UV absorbing aerosols. In contrast to the trend in aerosol optical depth found in the advanced very high-resolution radiometer data, no obvious long-term trend in absorbing aerosols is observed from the time series of AI records. The comparison between the mean annual cycle in the two data sets shows that the cycles agree very well both globally and regionally, indicating a consistency between the AI products from TOMS and OMI. Varimax rotated Empirical Orthogonal Function (EOF) analysis of detrended, deseasonalized AI data proves to be successful in isolating major dust and biomass burning source regions, as well as dust transport. Finally, we find that large, individual events, such as the Kuwait oil fire and Australian smoke plum, are isolated in individual higher-order principal components.

  8. Evolution of the complex refractive index in the UV spectral region in ageing secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Flores, J. M.; Zhao, D. F.; Segev, L.; Schlag, P.; Kiendler-Scharr, A.; Fuchs, H.; Watne, Å. K.; Bluvshtein, N.; Mentel, Th. F.; Hallquist, M.; Rudich, Y.

    2014-06-01

    The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are as yet still poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC, was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity-enhanced spectrometer for aerosol optical extinction measurements in the UV spectral region (360 to 420 nm). Chemical composition and volatility of the particles were monitored by a high-resolution time-of-flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i) a mixture of biogenic VOC (α-pinene and limonene), (ii) biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10), or (iii) a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone/OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after approximately the same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have a significant amount of semivolatile components. The

  9. Simultaneous Retrieval of Effective Refractive Index and Density from Size Distribution and Light Scattering Data: Weakly-Absorbing Aerosol

    SciTech Connect

    Kassianov, Evgueni I.; Barnard, James C.; Pekour, Mikhail S.; Berg, Larry K.; Shilling, John E.; Flynn, Connor J.; Mei, Fan; Jefferson, Anne

    2014-10-01

    We propose here a novel approach for retrieving in parallel the effective density and real refractive index of weakly absorbing aerosol from optical and size distribution measurements. Here we define “weakly absorbing” as aerosol single-scattering albedos that exceed 0.95 at 0.5 um.The required optical measurements are the scattering coefficient and the hemispheric backscatter fraction, obtained in this work from an integrating nephelometer. The required size spectra come from a Scanning Mobility Particle Sizer and an Aerodynamic Particle Sizer. The performance of this approach is first evaluated using a sensitivity study with synthetically generated but measurement-related inputs. The sensitivity study reveals that the proposed approach is robust to random noise; additionally the uncertainties of the retrieval are almost linearly proportional to the measurement errors, and these uncertainties are smaller for the real refractive index than for the effective density. Next, actual measurements are used to evaluate our approach. These measurements include the optical, microphysical, and chemical properties of weakly absorbing aerosol which are representative of a variety of coastal summertime conditions observed during the Two-Column Aerosol Project (TCAP; http://campaign.arm.gov/tcap/). The evaluation includes calculating the root mean square error (RMSE) between the aerosol characteristics retrieved by our approach, and the same quantities calculated using the conventional volume mixing rule for chemical constituents. For dry conditions (defined in this work as relative humidity less than 55%) and sub-micron particles, a very good (RMSE~3%) and reasonable (RMSE~28%) agreement is obtained for the retrieved real refractive index (1.49±0.02) and effective density (1.68±0.21), respectively. Our approach permits discrimination between the retrieved aerosol characteristics of sub-micron and sub-10micron particles. The evaluation results also reveal that the

  10. Inverse modeling of biomass burning emissions using Total Ozone Mapping Spectrometer aerosol index for 1997

    NASA Astrophysics Data System (ADS)

    Zhang, Sophia; Penner, Joyce E.; Torres, Omar

    2005-11-01

    We present results from an inverse model study to determine biomass smoke emissions for the year 1997 by comparison of modeled aerosol index (AI) with that measured by the EP TOMS instrument. The IMPACT model with Data Assimilation Office (DAO) meteorology data in 1997 is utilized to obtain aerosol spatial and temporal distributions. Then a radiative transfer model is applied to generate the modeled AI. A Bayesian inverse technique is applied to optimize the difference between the modeled AI and the EP TOMS AI in the same period by regulating monthly a priori biomass smoke emissions in seven predefined regions. The modeled AI with a posteriori emissions is generally in better agreement with the EP TOMS AI. The a posteriori emissions from Indonesia increase by a factor of 8-10 over the a priori emissions due to the Indonesian fires in 1997. The annual total a posteriori source increases by about 13% for the year 1997 (6.31 Tg/yr black carbon and 67.27 Tg/yr smoke) in the base scenario, with a larger adjustment of monthly emissions. The sensitivity of this result to the a priori uncertainties, the height of the smoke layer, the cloud screening criteria, the inclusion of an adjustment of emissions outside the main biomass burning regions, and the inclusion of the covariances between observations in different locations is discussed in a set of sensitivity scenarios. The sensitivity scenarios suggest that the inverse model results are most sensitive to the assumed uncertainty for a priori emissions and the altitude of aerosol layer in the model and are less sensitive to other factors. In the scenario where the uncertainty of a priori emissions is increased to 100% (300% in Indonesia), the total annual black carbon emission is increased to 6.87 Tg/yr, and the smoke emission increases to 73.39 Tg/yr. The a posteriori emissions in Indonesia in the scenario with increased uncertainty are in better agreement with both the TOMS AI and with previous estimates for the

  11. Psychological Evaluation of Animal-assisted Intervention (AAI) Programs Involving Visiting Dogs and Cats for Alcohol Dependents: A Pilot Study.

    PubMed

    Ohtani, Nobuyo; Narita, Shin; Yoshihara, Eiji; Ohta, Mitsuaki; Iwahashi, Kazuhiko

    2015-12-01

    The purpose of this study was to develop an evaluation method for animal-assisted intervention (AAI) programs involving Mood Check List-Short form.2 (MCL-S.2) and the State-Trait Anxiety Inventory (STAI) for psychiatric daycare of Japanese alcohol. dependents. A total of 36 alcohol dependents completed the study and questionnaires assessing their state. A single session of AAI reduced both subjective and physiological measures of state anxiety (A-State); and this program induced a significant reduction in the anxiety after an AAI program session with the dogs and cats involved in the intervention (p = 0.001). The Wilcoxon t-test showed that there were also significant differences in the "anxiety", "pleasantness", and "relaxation". scores for MCL-S.2 among the alcohol dependents, before and after AAI; a significantly decreased "anxiety" score (p = 0.006), and increased "pleasantness" (p = 0.002) and "relaxation" (p=0.012) scores for MCL-S.2 after AAI. The results of this study indicated that alcohol dependents who experienced a group AAI session-program exhibited significant improvements in their feeling; decreased anxiety, and increased pleasantness and relaxation.

  12. Retrieval of aerosol refractive index from extinction spectra with a damped harmonic-oscillator band model.

    PubMed

    Thomas, Gareth E; Bass, Stephen F; Grainger, Roy G; Lambert, Alyn

    2005-03-01

    A new method for the retrieval of the spectral refractive indices of micrometer-sized particles from infrared aerosol extinction spectra has been developed. With this method we use a classical damped harmonic-oscillator model of molecular absorption in conjunction with Mie scattering to model extinction spectra, which we then fit to the measurements using a numerical optimal estimation algorithm. The main advantage of this method over the more traditional Kramers-Kronig approach is that it allows the full complex refractive-index spectra, along with the parameters of the particle size distribution, to be retrieved from a single extinction spectrum. The retrieval scheme has been extensively characterized and has been found to provide refractive indices with a maximum uncertainty of approximately 10% (with a minimum of approximately 0.1%). Comparison of refractive indices calculated from measurements of a ternary solution of HNO3, H2SO4, and H2O with those published in J. Phys. Chem. A 104, 783 (2000) show similar differences as found by other authors.

  13. Author Affiliation Index: A New Approach to Marketing Journal Ranking

    ERIC Educational Resources Information Center

    Pan, Yue; Chen, Carl R.

    2011-01-01

    Previous research has adopted various methods to assess the relative quality of academic marketing journals. This study, as a replication and extension of Chen and Huang (2007), introduces the Author Affiliation Index (AAI) as an alternative approach to assessing marketing journal quality. The AAI is defined as the ratio of articles authored by…

  14. An aerosol boomerang: Rapid around-the-world transport of smoke from the December 2006 Australian forest fires observed from space

    NASA Astrophysics Data System (ADS)

    Dirksen, Ruud J.; Folkert Boersma, K.; de Laat, Jos; Stammes, Piet; van der Werf, Guido R.; Val Martin, Maria; Kelder, Hennie M.

    2009-11-01

    We investigate rapid around-the-world transport of a smoke aerosol plume released by intense forest fires in southeastern Australia in December 2006. During the first half of December 2006, southeastern Australia suffered from severe drought and exceptionally high temperatures. On 14 December 2006, a passing cold front in combination with the intense heat from the fires causing pyro-convective lofting, injected a large mass of aerosol particles into the jet stream. We track the resulting aerosol plume using Aerosol Absorbing Index (AAI) observations from the Ozone Monitoring Instrument (OMI) and find that it circumnavigated the world in 12 days. Using observations from OMI and the CALIOP (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) spaceborne lidar, we show that the plume resided in the high troposphere at different stages of its evolution. In absence of CALIOP data, we explored OMI O2-O2 pressures to obtain information on the aerosol plume height. Detailed radiative transfer calculations suggest that the current OMI O2-O2 retrievals contain useful information on the altitude of the aerosol plume under specific conditions (high AAI, no clouds below). The observed two-dimensional evolution of the smoke aerosol plume and the vertical distribution of the plume detected by CALIOP is matched by simulations with the TM4 chemistry transport model for an injection height of 248 hPa (˜10 km). Injection heights at the surface and at 540 hPa (˜5 km) resulted in simulated vertical distributions that were 2-3 km too low relative to CALIOP observations and showed less agreement with the AAI patterns. The high injection altitude of 10 km mimics the effect of pyro-convective lofting as the additional buoyancy from the intense fires is not accounted for in the model. TM4 simulations with an inert and a water-soluble tracer reproduce the observed dilution of the plume and show that the latter gives the best agreement with the observations, suggesting that

  15. Interpreting the ultraviolet aerosol index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects

    NASA Astrophysics Data System (ADS)

    Hammer, Melanie S.; Martin, Randall V.; van Donkelaar, Aaron; Buchard, Virginie; Torres, Omar; Ridley, David A.; Spurr, Robert J. D.

    2016-03-01

    Satellite observations of the ultraviolet aerosol index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.32 to -0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The inclusion of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.57 to -0.09 over West Africa in January, from -0.32 to +0.0002 over South Asia in April, from -0.97 to -0.22 over southern Africa in July, and from -0.50 to +0.33 over South America in September. The spectral dependence of absorption after including BrC in the model is broadly consistent with reported observations for biomass burning aerosol, with absorbing Ångström exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 30 % over South America in September, up to 20 % over southern Africa in July, and up to 15 % over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years

  16. Interpreting the Ultraviolet Aerosol Index observed with the OMI satellite instrument to understand absorption by organic aerosols: implications for atmospheric oxidation and direct radiative effects

    NASA Astrophysics Data System (ADS)

    Hammer, M. S.; Martin, R. V.; van Donkelaar, A.; Buchard, V.; Torres, O.; Ridley, D. A.; Spurr, R. J. D.

    2015-10-01

    Satellite observations of the Ultraviolet Aerosol Index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOS-Chem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.32 to -0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The addition of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.57 to -0.09 over West Africa in January, from -0.32 to +0.0002 over South Asia in April, from -0.97 to -0.22 over southern Africa in July, and from -0.50 to +0.33 over South America in September. The spectral dependence of absorption after adding BrC to the model is broadly consistent with reported observations for biomass burning aerosol, with Absorbing Angstrom Exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 35 % over South America in September, up to 25 % over southern Africa in July, and up to 20 % over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years, thus

  17. Interpreting the Ultraviolet Aerosol Index Observed with the OMI Satellite Instrument to Understand Absorption by Organic Aerosols: Implications for Atmospheric Oxidation and Direct Radiative Effects

    NASA Technical Reports Server (NTRS)

    Hammer, Melanie S.; Martin, Randall V.; Donkelaar, Aaron van; Buchard, Virginie; Torres, Omar; Ridley, David A.; Spurr, Robert J. D.

    2016-01-01

    Satellite observations of the ultraviolet aerosol index (UVAI) are sensitive to absorption of solar radiation by aerosols; this absorption affects photolysis frequencies and radiative forcing. We develop a global simulation of the UVAI using the 3-D chemical transport model GEOSChem coupled with the Vector Linearized Discrete Ordinate Radiative Transfer model (VLIDORT). The simulation is applied to interpret UVAI observations from the Ozone Monitoring Instrument (OMI) for the year 2007. Simulated and observed values are highly consistent in regions where mineral dust dominates the UVAI, but a large negative bias (-0.32 to -0.97) exists between simulated and observed values in biomass burning regions. We determine effective optical properties for absorbing organic aerosol, known as brown carbon (BrC), and implement them into GEOS-Chem to better represent observed UVAI values over biomass burning regions. The inclusion of absorbing BrC decreases the mean bias between simulated and OMI UVAI values from -0.57 to -0.09 over West Africa in January, from -0.32 to +0.0002 over South Asia in April, from -0.97 to -0.22 over southern Africa in July, and from -0.50 to +0.33 over South America in September. The spectral dependence of absorption after including BrC in the model is broadly consistent with reported observations for biomass burning aerosol, with absorbing Angstrom exponent (AAE) values ranging from 2.9 in the ultraviolet (UV) to 1.3 across the UV-Near IR spectrum. We assess the effect of the additional UV absorption by BrC on atmospheric photochemistry by examining tropospheric hydroxyl radical (OH) concentrations in GEOS-Chem. The inclusion of BrC decreases OH by up to 30% over South America in September, up to 20% over southern Africa in July, and up to 15% over other biomass burning regions. Global annual mean OH concentrations in GEOS-Chem decrease due to the presence of absorbing BrC, increasing the methyl chloroform lifetime from 5.62 to 5.68 years, thus

  18. Evaluation of a quantitative structure-property relationship (QSPR) for predicting mid-visible refractive index of secondary organic aerosol (SOA).

    PubMed

    Redmond, Haley; Thompson, Jonathan E

    2011-04-21

    In this work we describe and evaluate a simple scheme by which the refractive index (λ = 589 nm) of non-absorbing components common to secondary organic aerosols (SOA) may be predicted from molecular formula and density (g cm(-3)). The QSPR approach described is based on three parameters linked to refractive index-molecular polarizability, the ratio of mass density to molecular weight, and degree of unsaturation. After computing these quantities for a training set of 111 compounds common to atmospheric aerosols, multi-linear regression analysis was conducted to establish a quantitative relationship between the parameters and accepted value of refractive index. The resulting quantitative relationship can often estimate refractive index to ±0.01 when averaged across a variety of compound classes. A notable exception is for alcohols for which the model consistently underestimates refractive index. Homogenous internal mixtures can conceivably be addressed through use of either the volume or mole fraction mixing rules commonly used in the aerosol community. Predicted refractive indices reconstructed from chemical composition data presented in the literature generally agree with previous reports of SOA refractive index. Additionally, the predicted refractive indices lie near measured values we report for λ = 532 nm for SOA generated from vapors of α-pinene (R.I. 1.49-1.51) and toluene (R.I. 1.49-1.50). We envision the QSPR method may find use in reconstructing optical scattering of organic aerosols if mass composition data is known. Alternatively, the method described could be incorporated into in models of organic aerosol formation/phase partitioning to better constrain organic aerosol optical properties.

  19. Airborne Coarse Mode Aerosol Measurements with the CAS-DPOL Instrument: Effects of Particle Shape and Refractive Index and Implications for Radiative Transfer Estimate

    NASA Astrophysics Data System (ADS)

    Sauer, D. N.; Weinzierl, B.; Gasteiger, J.; Spanu, A.; Freudenthaler, V.; Gross, S.

    2015-12-01

    Each year huge amounts of mineral dust are mobilized in deserts and arid regions of the world and transported over large distances forming thick elevated aerosol layers with a substantial fraction of coarse mode particles. Optical properties of mineral dust, including the absorptive refractive index of some components, cause a significant effect on the atmospheric radiative energy balance from optical to infrared wavelengths. The aerosol characteristics, in particular its coarse mode size distribution, are modified during long-range transport by aging and deposition processes. This also affects the aerosol optical properties and therefore the effect on the atmospheric radiative energy budget. In-situ measurements of aerosol microphysical properties are essential to characterize those effects in order to be implemented in global climate models in parametrized form. However, in-situ measurements of airborne coarse mode aerosols such as mineral dust and volcanic ash are challenging and the measurements are usually affected by substantial uncertainties. In this work we use airborne measurements of mineral dust from our optical light-scattering spectrometer CAS-DPOL during SALTRACE 2013 to discuss the analysis of such data. We cover the effects of varying refractive index and particle shapes and develop recommendations for the configuration of the CAS-DPOL for aerosol studies. We also present an inversion method to derive coarse mode size distributions from light-scattering probes for mixtures of non-spherical, absorbing aerosols. The size distributions retrieved from the in-situ measurements are then validated using an independent analysis with a combination of sun-photometer and lidar data. We apply these methods to investigate the Saharan mineral dust particle size distributions measured on both sides of the Atlantic Ocean and discuss the influence of aerosol aging on the atmospheric radiative energy budget. With this example we also assess how the uncertainties

  20. Evaluation of the impact of atmospheric ozone and aerosols on the horizontal global/diffuse UV Index at Livorno (Italy)

    NASA Astrophysics Data System (ADS)

    Scaglione, Daniele; Giulietti, Danilo; Morelli, Marco

    2016-08-01

    A study was conducted at Livorno (Italy) to evaluate the impact of atmospheric aerosols and ozone on the solar UV radiation and its diffuse component at ground in clear sky conditions. Solar UV radiation has been quantified in terms of UV Index (UVI), following the ISO 17166:1999/CIE S007/E-1998 international standard. UVI has been calculated by exploiting the libRadtran radiative transfer modelling software as a function of both the Aerosols Optical Depth (AOD) and the Total Ozone Column (TOC). In particular AOD and TOC values have been remotely sensed by the Ozone Monitoring Instrument (OMI) on board the NASA's EOS (Earth Observing System) satellites constellation. An experimental confirmation was also obtained by exploiting global UVI ground-based measurements from the 26/9/14 to 12/8/15 and diffuse UVI ground-based measurements from the 17/5/15 to 12/8/15. For every considered value of Solar Zenith Angle (SZA) and atmospheric condition, estimates and measurements confirm that the diffuse component contributes for more than 50% on the global UV radiation. Therefore an exposure of human skin also to diffuse solar UV radiation can be potentially harmful for health and need to be accurately monitored, e.g. by exploiting innovative applications such as a mobile app with a satellite-based UV dosimeter that has been developed. Global and diffuse UVI variations due to the atmosphere are primarily caused by the TOC variations (typically cyclic): the maximum TOC variation detected by OMI in the area under study leads to a corresponding variation in global and diffuse UVI of about 50%. Aerosols in the area concerned, mainly of maritime nature, have instead weaker effects causing a maximum variation of the global and diffuse UVI respectively of 9% and 35% with an SZA of 20° and respectively of 13% and 10% with an SZA of 60°.

  1. Evolution of the complex refractive index in the near UV spectral region in ageing secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Flores, J. M.; Zhao, D. F.; Segev, L.; Schlag, P.; Kiendler-Scharr, A.; Fuchs, H.; Watne, Å. K.; Bluvshtein, N.; Mentel, Th. F.; Hallquist, M.; Rudich, Y.

    2014-02-01

    The chemical and physical properties of secondary organic aerosol (SOA) formed by the photochemical degradation of biogenic and anthropogenic volatile organic compounds (VOC) are yet poorly constrained. The evolution of the complex refractive index (RI) of SOA, formed from purely biogenic VOC and mixtures of biogenic and anthropogenic VOC was studied over a diurnal cycle in the SAPHIR photochemical outdoor chamber in Jülich, Germany. The correlation of RI with SOA chemical and physical properties such as oxidation level and volatility was examined. The RI was retrieved by a newly developed broadband cavity enhanced spectrometer for aerosol optical extinction measurements in the near UV spectral region (360 to 420 nm). Chemical composition and volatility of the particles were monitored by a high resolution time of flight aerosol mass spectrometer, and a volatility tandem differential mobility analyzer. SOA was formed by ozonolysis of either (i) a mixture of biogenic VOC (α-pinene and limonene), (ii) biogenic VOC mixture with subsequent addition of an anthropogenic VOC (p-xylene-d10), or (iii) a mixture of biogenic and anthropogenic VOC. The SOA aged by ozone / OH reactions up to 29.5 h was found to be non-absorbing in all cases. The SOA with p-xylene-d10 showed an increase of the scattering component of the RI correlated with an increase of the O / C ratio and with an increase in the SOA density. There was a greater increase in the scattering component of the RI when the SOA was produced from the mixture of biogenic VOCs and anthropogenic VOC than from the sequential addition of the VOCs after the approximate same ageing time. The increase of the scattering component was inversely correlated with the SOA volatility. Two RI retrievals determined for the pure biogenic SOA showed a constant RI for up to 5 h of ageing. Mass spectral characterization shows the three types of the SOA formed in this study have significant amount of semivolatile components. The influence

  2. An Empirical Function for Bidirectional Reflectance Characterization for Smoke Aerosols Using Multi-angular Airborne Measurements

    NASA Astrophysics Data System (ADS)

    Poudyal, R.; Singh, M. K.; Gatebe, C. K.; Gautam, R.; Varnai, T.

    2015-12-01

    Using airborne Cloud Absorption Radiometer (CAR) reflectance measurements of smoke, an empirical relationship between reflectances measured at different sun-satellite geometry is established, in this study. It is observed that reflectance of smoke aerosol at any viewing zenith angle can be computed using a linear combination of reflectance at two viewing zenith angles. One of them should be less than 30° and other must be greater than 60°. We found that the parameters of the linear combination computation follow a third order polynomial function of the viewing geometry. Similar relationships were also established for different relative azimuth angles. Reflectance at any azimuth angle can be written as a linear combination of measurements at two different azimuth angles. One must be in the forward scattering direction and the other in backward scattering, with both close to the principal plane. These relationships allowed us to create an Angular Distribution Model (ADM) for smoke, which can estimate reflectances in any direction based on measurements taken in four view directions. The model was tested by calculating the ADM parameters using CAR data from the SCAR-B campaign, and applying these parameters to different smoke cases at three spectral channels (340nm, 380nm and 470nm). We also tested our modelled smoke ADM formulas with Absorbing Aerosol Index (AAI) directly computed from the CAR data, based on 340nm and 380nm, which is probably the first study to analyze the complete multi-angular distribution of AAI for smoke aerosols. The RMSE (and mean error) of predicted reflectance for SCAR-B and ARCTAS smoke ADMs were found to be 0.002 (1.5%) and 0.047 (6%), respectively. The accuracy of the ADM formulation is also tested through radiative transfer simulations for a wide variety of situations (varying smoke loading, underlying surface types, etc.).

  3. Isolation and characterization of a proteinaceous α-amylase inhibitor AAI-CC5 from Streptomyces sp. CC5, and its gene cloning and expression.

    PubMed

    Sun, Zhibin; Lu, Weihao; Liu, Pingping; Wang, Hui; Huang, Yan; Zhao, Yuguo; Kong, Yi; Cui, Zhongli

    2015-02-01

    An α-amylase inhibitor producing Streptomyces sp. strain CC5 was isolated from soil. A proteinaceous α-amylase inhibitor AAI-CC5 was purified from strain CC5. AAI-CC5 specifically inhibited mammalian α-amylases. The molecular weight of the inhibitor was determined to be 8,212 Da by MALDI-TOF Mass Spectrum. The N-terminal 15 amino acid residues of the purified AAI-CC5 were DTGSPAPECVEYFQS, which is dissimilar to other reported proteinaceous α-amylase inhibitors. AAI-CC5 is a pH insensitive and heat-stable protein, and cannot be hydrolysed by trypsin. AAI-CC5 was cloned and expressed in Escherichia coli BL21 (DE3) with a hexa-histidine tag on the C terminal. AAI-CC5 shared 82 % identity with Parvulustat. The recombinant α-amylase inhibitor was purified to homogeneity by one-step affinity chromatography using Ni(2+)-NTA resin with molecular mass of 9,404 Da. Steady state kinetics studies of α-amylase and the inhibitor revealed an irreversible, non-competitive inhibition mechanism with IC50 and Ki value of 6.43 ×1 10(-11) and 4.45 × 10(-11) M respectively. These results suggest this novel α-amylase inhibitor possessed powerful inhibitory activity for α-amylase, and it may be a candidate in research of diabetes therapy and obesity treatment.

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  5. The EGI-Engage EPOS Competence Center - Interoperating heterogeneous AAI mechanisms and Orchestrating distributed computational resources

    NASA Astrophysics Data System (ADS)

    Bailo, Daniele; Scardaci, Diego; Spinuso, Alessandro; Sterzel, Mariusz; Schwichtenberg, Horst; Gemuend, Andre

    2016-04-01

    manage the use of the subsurface of the Earth. EPOS started its Implementation Phase in October 2015 and is now actively working in order to integrate multidisciplinary data into a single e-infrastructure. Multidisciplinary data are organized and governed by the Thematic Core Services (TCS) - European wide organizations and e-Infrastructure providing community specific data and data products - and are driven by various scientific communities encompassing a wide spectrum of Earth science disciplines. TCS data, data products and services will be integrated into the Integrated Core Services (ICS) system, that will ensure their interoperability and access to these services by the scientific community as well as other users within the society. The EPOS competence center (EPOS CC) goal is to tackle two of the main challenges that the ICS are going to face in the near future, by taking advantage of the technical solutions provided by EGI. In order to do this, we will present the two pilot use cases the EGI-EPOS CC is developing: 1) The AAI pilot, dealing with the provision of transparent and homogeneous access to the ICS infrastructure to users owning different kind of credentials (e.g. eduGain, OpenID Connect, X509 certificates etc.). Here the focus is on the mechanisms which allow the credential delegation. 2) The computational pilot, Improve the back-end services of an existing application in the field of Computational Seismology, developed in the context of the EC funded project VERCE. The application allows the processing and the comparison of data resulting from the simulation of seismic wave propagation following a real earthquake and real measurements recorded by seismographs. While the simulation data is produced directly by the users and stored in a Data Management System, the observations need to be pre-staged from institutional data-services, which are maintained by the community itself. This use case aims at exploiting the EGI FedCloud e-infrastructure for Data

  6. Method for estimation of refractive index and size distribution of aerosol using direct and diffuse solar irradiance and aureole by means of simulated annealing

    NASA Astrophysics Data System (ADS)

    Arai, Kohei; Liang, XingMing

    2003-12-01

    An estimation method for refractive index and size distribution of aerosols using measurements of direct and diffuse solar irradiance as well as the solar aureole by means of a modified simulated annealing is proposed. The proposed method is based on simulated annealing modified to acceralate a learning process by using a gradually decreasing oscillation function of temperature of annealing. By a using Gauss Seidel based atmospheric code, simulation data of direct and diffuse solar irradiance are generated together with estimated aureole measurements by means of an empirical method derived from experimental data. A comparison between the existing method proposed by P Romanov et.al. based on a linear inversion method and the proposed method is made. The results show double improvement of the estimation accuracy for both the aerosol size distribution and refractive index.

  7. Inversion of the anomalous diffraction approximation for variable complex index of refraction near unity. [numerical tests for water-haze aerosol model

    NASA Technical Reports Server (NTRS)

    Smith, C. B.

    1982-01-01

    The Fymat analytic inversion method for retrieving a particle-area distribution function from anomalous diffraction multispectral extinction data and total area is generalized to the case of a variable complex refractive index m(lambda) near unity depending on spectral wavelength lambda. Inversion tests are presented for a water-haze aerosol model. An upper-phase shift limit of 5 pi/2 retrieved an accurate peak area distribution profile. Analytical corrections using both the total number and area improved the inversion.

  8. Impact of Radiatively Interactive Dust Aerosols in the NASA GEOS-5 Climate Model: Sensitivity to Dust Particle Shape and Refractive Index

    NASA Technical Reports Server (NTRS)

    Colarco, Peter R.; Nowottnick, Edward Paul; Randles, Cynthia A.; Yi, Bingqi; Yang, Ping; Kim, Kyu-Myong; Smith, Jamison A.; Bardeen, Charles D.

    2013-01-01

    We investigate the radiative effects of dust aerosols in the NASA GEOS-5 atmospheric general circulation model. GEOS-5 is improved with the inclusion of a sectional aerosol and cloud microphysics module, the Community Aerosol and Radiation Model for Atmospheres (CARMA). Into CARMA we introduce treatment of the dust and sea salt aerosol lifecycle, including sources, transport evolution, and sinks. The aerosols are radiatively coupled to GEOS-5, and we perform a series of multi-decade AMIP-style simulations in which dust optical properties (spectral refractive index and particle shape distribution) are varied. Optical properties assuming spherical dust particles are from Mie theory, while those for non-spherical shape distributions are drawn from a recently available database for tri-axial ellipsoids. The climatologies of the various simulations generally compare well to data from the MODIS, MISR, and CALIOP space-based sensors, the ground-based AERONET, and surface measurements of dust deposition and concentration. Focusing on the summertime Saharan dust cycle we show significant variability in our simulations resulting from different choices of dust optical properties. Atmospheric heating due to dust enhances surface winds over important Saharan dust sources, and we find a positive feedback where increased dust absorption leads to increased dust emissions. We further find that increased dust absorption leads to a strengthening of the summertime Hadley cell circulation, increasing dust lofting to higher altitudes and strengthening the African Easterly Jet. This leads to a longer atmospheric residence time, higher altitude, and generally more northward transport of dust in simulations with the most absorbing dust optical properties. We find that particle shape, although important for radiance simulations, is a minor effect compared to choices of refractive index, although total atmospheric forcing is enhanced by greater than 10 percent for simulations incorporating a

  9. Refractive Index and Absorption Attribution of Highly Absorbing Brown Carbon Aerosols from an Urban Indian City-Kanpur

    NASA Astrophysics Data System (ADS)

    Shamjad, P. M.; Tripathi, S. N.; Thamban, Navaneeth M.; Vreeland, Heidi

    2016-11-01

    Atmospheric aerosols influence Earth’s radiative balance, having both warming and cooling effects. Though many aerosols reflect radiation, carbonaceous aerosols such as black carbon and certain organic carbon species known as brown carbon have the potential to warm the atmosphere by absorbing light. Black carbon absorbs light over the entire solar spectrum whereas brown carbon absorbs near-UV wavelengths and, to a lesser extent, visible light. In developing countries, such as India, where combustion sources are prolific, the influence of brown carbon on absorption may be significant. In order to better characterize brown carbon, we present experimental and modeled absorption properties of submicron aerosols measured in an urban Indian city (Kanpur). Brown carbon here is found to be fivefold more absorbing at 365 nm wavelength compared to previous studies. Results suggest ~30% of total absorption in Kanpur is attributed to brown carbon, with primary organic aerosols contributing more than secondary organics. We report the spectral brown carbon refractive indices along with an experimentally constrained estimate of the influence of aerosol mixing state on absorption. We conclude that brown carbon in Kanpur is highly absorbing in nature and that the mixing state plays an important role in light absorption from volatile species.

  10. Refractive Index and Absorption Attribution of Highly Absorbing Brown Carbon Aerosols from an Urban Indian City-Kanpur.

    PubMed

    Shamjad, P M; Tripathi, S N; Thamban, Navaneeth M; Vreeland, Heidi

    2016-11-24

    Atmospheric aerosols influence Earth's radiative balance, having both warming and cooling effects. Though many aerosols reflect radiation, carbonaceous aerosols such as black carbon and certain organic carbon species known as brown carbon have the potential to warm the atmosphere by absorbing light. Black carbon absorbs light over the entire solar spectrum whereas brown carbon absorbs near-UV wavelengths and, to a lesser extent, visible light. In developing countries, such as India, where combustion sources are prolific, the influence of brown carbon on absorption may be significant. In order to better characterize brown carbon, we present experimental and modeled absorption properties of submicron aerosols measured in an urban Indian city (Kanpur). Brown carbon here is found to be fivefold more absorbing at 365 nm wavelength compared to previous studies. Results suggest ~30% of total absorption in Kanpur is attributed to brown carbon, with primary organic aerosols contributing more than secondary organics. We report the spectral brown carbon refractive indices along with an experimentally constrained estimate of the influence of aerosol mixing state on absorption. We conclude that brown carbon in Kanpur is highly absorbing in nature and that the mixing state plays an important role in light absorption from volatile species.

  11. Refractive Index and Absorption Attribution of Highly Absorbing Brown Carbon Aerosols from an Urban Indian City-Kanpur

    PubMed Central

    Shamjad, P. M.; Tripathi, S. N.; Thamban, Navaneeth M.; Vreeland, Heidi

    2016-01-01

    Atmospheric aerosols influence Earth’s radiative balance, having both warming and cooling effects. Though many aerosols reflect radiation, carbonaceous aerosols such as black carbon and certain organic carbon species known as brown carbon have the potential to warm the atmosphere by absorbing light. Black carbon absorbs light over the entire solar spectrum whereas brown carbon absorbs near-UV wavelengths and, to a lesser extent, visible light. In developing countries, such as India, where combustion sources are prolific, the influence of brown carbon on absorption may be significant. In order to better characterize brown carbon, we present experimental and modeled absorption properties of submicron aerosols measured in an urban Indian city (Kanpur). Brown carbon here is found to be fivefold more absorbing at 365 nm wavelength compared to previous studies. Results suggest ~30% of total absorption in Kanpur is attributed to brown carbon, with primary organic aerosols contributing more than secondary organics. We report the spectral brown carbon refractive indices along with an experimentally constrained estimate of the influence of aerosol mixing state on absorption. We conclude that brown carbon in Kanpur is highly absorbing in nature and that the mixing state plays an important role in light absorption from volatile species. PMID:27883083

  12. Interpretation of Aura satellite observations of CO and aerosol index related to the December 2006 Australia fires

    NASA Astrophysics Data System (ADS)

    Luo, M.; Boxe, C.; Jiang, J.; Nassar, R.; Livesey, N.

    2009-11-01

    Enhanced Carbon Monoxide (CO) in the upper troposphere (UT) is shown by collocated Tropospheric Emission Spectrometer (TES) and Microwave Limb Sounder (MLS) measurements near and down-wind from the known wildfire region of SE Australia from 12-19 December 2006. Enhanced UV aerosol index (AI) derived from Ozone Monitoring Instrument (OMI) measurements correlate with these high CO concentrations. HYSPLIT model back trajectories trace selected air parcels to the SE Australia fire region as their initial location, where TES observes enhanced CO in the upper and lower troposphere. Simultaneously, they show a lack of vertical advection along their tracks. TES retrieved CO vertical profiles in the higher and lower southern latitudes are examined together with the averaging kernels and show that TES CO retrievals are most sensitive at approximately 300-400 hPa. The enhanced CO observed by TES at the upper (215 hPa) and lower (681 hPa) troposphere are, therefore, influenced by mid-tropospheric CO. GEOS-Chem model simulations with an 8-day emission inventory, as the wildfire source over Australia, are sampled to the TES/MLS observation times and locations. These simulations only show CO enhancements in the lower troposphere near and down-wind from the wildfire region of SE Australia with drastic underestimates of UT CO. Although CloudSat along-track ice-water content curtains are examined to see whether possible vertical convection events can explain the high UT CO values, sparse observations of collocated Aura CO and CloudSat along-track ice-water content measurements for the single event precludes any conclusive correlation. Vertical convection that uplift fire-induced CO (i.e. most notably referred to as pyro-cumulonimbus, pyroCb) may provide an explanation for the incongruence between these simulations and the TES/MLS observations of enhanced CO in the UT. Future GEOS-Chem simulations are needed to validate this conjecture as the the PyroCb mechanism is currently not

  13. Interpretation of Aura Satellite Observations of CO and Aerosol Index related to the December 2006 Australia Fires

    NASA Astrophysics Data System (ADS)

    Luo, M.; Boxe, C. S.; Jiang, J. H.; Nassar, R.; Logan, J. A.; Livesey, N. J.

    2009-12-01

    Enhanced Carbon Monoxide (CO) in the upper troposphere (UT) is shown by collocated Tropospheric Emission Spectrometer (TES) and Microwave Limb Sounder (MLS) measurements near and down-wind from the known wildfire region of SE Australia, December 12th-19th, 2006. Enhanced UV aerosol index (AI) derived from Ozone Monitoring Instrument (OMI) measurements correlate with these high CO concentrations. HYSPLIT model back trajectories trace selected air parcels to the SE Australia fire region from the initial locations with enhanced TES CO in the upper and lower troposphere. Simultaneously, they show a lack of vertical advection along their tracks. TES retrieved CO vertical profiles in the higher and lower southern latitudes are examined together with the averaging kernels and show that TES CO retrievals are most sensitive at approximately 300-400 hPa. The enhanced CO observed by TES at the upper (215 hPa) and lower (681 hPa) troposphere are therefore influenced by mid-tropospheric CO. GEOS-Chem model simulations with an 8-day emissions inventory as the wildfire source over Australia, are sampled to the TES/MLS observation times and locations. These simulations only show CO enhancements in the lower troposphere near and down-wind from the wildfire region of SE Australia with drastic underestimates of UT CO. Although CloudSat along-track ice-water content curtains are examined to see whether possible vertical convection events can explain the high UT CO values, sparse observations of collocated Aura CO and CloudSat along-track ice-water content measurements for the single event precludes any conclusive correlation. Vertical convection that uplift fire-induced CO (i.e., most notably referred to as pyro-cumulonimbus (pyroCb)) is likely responsible for the TES/MLS observations. The PyroCb mechanism is currently not incorporated in GEOS-Chem, thus providing a potential explanation for the incongruence between its simulations and TES/MLS observations of enhanced CO in the UT.

  14. Adult attachment interviews of women from low-risk, poverty, and maltreatment risk samples: comparisons between the hostile/helpless and traditional AAI coding systems.

    PubMed

    Frigerio, Alessandra; Costantino, Elisabetta; Ceppi, Elisa; Barone, Lavinia

    2013-01-01

    The main aim of this study was to investigate the correlates of a Hostile-Helpless (HH) state of mind among 67 women belonging to a community sample and two different at-risk samples matched on socio-economic indicators, including 20 women from low-SES population (poverty sample) and 15 women at risk for maltreatment being monitored by the social services for the protection of juveniles (maltreatment risk sample). The Adult Attachment Interview (AAI) protocols were reliably coded blind to the samples' group status. The rates of HH classification increased in relation to the risk status of the three samples, ranging from 9% for the low-risk sample to 60% for the maltreatment risk sample to 75% for mothers in the maltreatment risk sample who actually maltreated their infants. In terms of the traditional AAI classification system, 88% of the interviews from the maltreating mothers were classified Unresolved/Cannot Classify (38%) or Preoccupied (50%). Partial overlapping between the 2 AAI coding systems was found, and discussion concerns the relevant contributions of each AAI coding system to understanding of the intergenerational transmission of maltreatment.

  15. Midtemperature solar systems test facility predictions for thermal performance based on test data: AAI solar collector with pressure-formed glass reflector surface

    SciTech Connect

    Harrison, T.D.

    1981-03-01

    Sandia National Laboratories, Albuquerque (SNLA), is currently conducting a program to predict the performance and measure the characteristics of commercially available solar collectors that have the potential for use in industrial process heat and enhance oil recovery applications. The thermal performance predictions for the AAI solar line-focusing slat-type collector for five cities in the US are presented. (WHK)

  16. Retrieval of aerosol complex refractive index from a synergy between lidar, sunphotometer and in situ measurements during LISAIR experiment

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

    Particulate pollutant exchanges between the streets and the Planetary Boundary Layer (PBL), and their daily evolution linked to human activity were studied in the framework of the LIdar pour la Surveillance de l'AIR (LISAIR) experiment. This program lasted from 10 to 30 May 2005. A synergetic approach combining dedicated active (lidar) and passive (sunphotometer) remote sensors as well as ground based in situ instrumentation (nephelometer, aethalometer and particle sizers) was used to investigate urban aerosol optical properties within Paris. Aerosol complex refractive indices were assessed to be 1.56-0.034 i at 355 nm and 1.59-0.040 i at 532 nm, thus leading to single-scattering albedo values between 0.80 and 0.88. These retrievals are consistent with soot components in the aerosol arising from traffic exhausts indicating that these pollutants have a radiative impact on climate. We also discussed the influence of relative humidity on aerosol properties. A good agreement was found between vertical extinction profile derived from lidar backscattering signal and retrieved from the coupling between radiosounding and ground in situ measurements.

  17. Retrieval of aerosol complex refractive index from a synergy between lidar, sunphotometer and in situ measurements during LISAIR experiment

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

    Particulate pollutant exchanges between the streets and the Planetary Boundary Layer (PBL), and their daily evolution linked to human activity were studied in the framework of the LIdar pour la Surveillance de l'AIR (LISAIR) experiment. This program lasted from 10 to 30 May 2005. A synergetic approach combining dedicated active (lidar) and passive (sunphotometer) remote sensors as well as ground based in situ instrumentation (nephelometer, aethalometer and particle sizers) was used to investigate urban aerosol optical properties within Paris. Aerosol complex refractive indices were assessed to be 1.56-0.034i at 355 nm and 1.59-0.040i at 532 nm, thus leading to single-scattering albedo values between 0.80 and 0.88. These retrievals are consistent with soot components in the aerosol arising from traffic exhausts indicating that these pollutants have a radiative impact on climate. We also discussed the influence of relative humidity on aerosol properties. A good agreement was found between vertical extinction profile derived from lidar backscattering signal and retrieved from the coupling between radiosounding and ground in situ measurements.

  18. Development, Comparisons and Evaluation of Aerosol Retrieval Algorithms

    NASA Astrophysics Data System (ADS)

    de Leeuw, G.; Holzer-Popp, T.; Aerosol-cci Team

    2011-12-01

    The Climate Change Initiative (cci) of the European Space Agency (ESA) has brought together a team of European Aerosol retrieval groups working on the development and improvement of aerosol retrieval algorithms. The goal of this cooperation is the development of methods to provide the best possible information on climate and climate change based on satellite observations. To achieve this, algorithms are characterized in detail as regards the retrieval approaches, the aerosol models used in each algorithm, cloud detection and surface treatment. A round-robin intercomparison of results from the various participating algorithms serves to identify the best modules or combinations of modules for each sensor. Annual global datasets including their uncertainties will then be produced and validated. The project builds on 9 existing algorithms to produce spectral aerosol optical depth (AOD and Ångström exponent) as well as other aerosol information; two instruments are included to provide the absorbing aerosol index (AAI) and stratospheric aerosol information. The algorithms included are: - 3 for ATSR (ORAC developed by RAL / Oxford university, ADV developed by FMI and the SU algorithm developed by Swansea University ) - 2 for MERIS (BAER by Bremen university and the ESA standard handled by HYGEOS) - 1 for POLDER over ocean (LOA) - 1 for synergetic retrieval (SYNAER by DLR ) - 1 for OMI retreival of the absorbing aerosol index with averaging kernel information (KNMI) - 1 for GOMOS stratospheric extinction profile retrieval (BIRA) The first seven algorithms aim at the retrieval of the AOD. However, each of the algorithms used differ in their approach, even for algorithms working with the same instrument such as ATSR or MERIS. To analyse the strengths and weaknesses of each algorithm several tests are made. The starting point for comparison and measurement of improvements is a retrieval run for 1 month, September 2008. The data from the same month are subsequently used for

  19. Atmospheric aerosols: Their Optical Properties and Effects

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Measured properties of atmospheric aerosol particles are presented. These include aerosol size frequency distribution and complex retractive index. The optical properties of aerosols are computed based on the presuppositions of thermodynamic equilibrium and of Mie-theory.

  20. A-line, bispectral index, and estimated effect-site concentrations: a prediction of clinical end-points of anesthesia.

    PubMed

    Kreuer, Sascha; Bruhn, Jörgen; Larsen, Reinhard; Buchinger, Heiko; Wilhelm, Wolfram

    2006-04-01

    Autoregressive modeling with exogenous input of middle-latency auditory evoked potentials (A-Line AEP index, AAI) has been developed for monitoring depth of anesthesia. We investigated the prediction of recovery and dose-response relationship of desflurane and AAI or bispectral index (BIS) values. Twenty adult men scheduled for radical prostatectomy were recruited. To minimize opioid effects, analgesia was provided by a concurrent epidural in addition to the general anesthetic. Electrodes for AAI and BIS monitoring and a headphone for auditory stimuli were applied. Propofol and remifentanil were used for anesthetic induction. Maintenance of anesthesia was with desflurane only. For comparison to AAI and BIS monitor parameters, pharmacokinetic models for desflurane and propofol distribution and effect-site concentrations were used to predict clinical end-points (Prediction probability P(K)). Patients opened their eyes at an AAI value of 47 +/- 20 and a BIS value of 77 +/- 14 (mean +/- sd), and the prediction probability for eye opening was P(K) = 0.81 for AAI, P(K) = 0.89 for BIS, and P(K) = 0.91 for desflurane effect-site concentration. The opening of eyes was best predicted by the calculated desflurane effect-site concentration. The relationship between predicted desflurane effect-site concentration versus AAI and BIS was calculated by nonlinear regression analysis (r = 0.75 for AAI and r = 0.80 for BIS). The correlation between BIS and clinical end-points of anesthesia or the desflurane effect-compartment concentration is better than for the AAI.

  1. Airborne characterization of subsaturated aerosol hygroscopicity and dry refractive index from the surface to 6.5 km during the SEAC4RS campaign

    NASA Astrophysics Data System (ADS)

    Shingler, Taylor; Crosbie, Ewan; Ortega, Amber; Shiraiwa, Manabu; Zuend, Andreas; Beyersdorf, Andreas; Ziemba, Luke; Anderson, Bruce; Thornhill, Lee; Perring, Anne E.; Schwarz, Joshua P.; Campazano-Jost, Pedro; Day, Douglas A.; Jimenez, Jose L.; Hair, Johnathan W.; Mikoviny, Tomas; Wisthaler, Armin; Sorooshian, Armin

    2016-04-01

    In situ aerosol particle measurements were conducted during 21 NASA DC-8 flights in the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys field campaign over the United States, Canada, Pacific Ocean, and Gulf of Mexico. For the first time, this study reports rapid, size-resolved hygroscopic growth and real refractive index (RI at 532 nm) data between the surface and upper troposphere in a variety of air masses including wildfires, agricultural fires, biogenic, marine, and urban outflow. The Differential Aerosol Sizing and Hygroscopicity Spectrometer Probe (DASH-SP) quantified size-resolved diameter growth factors (GF = Dp,wet/Dp,dry) that are used to infer the hygroscopicity parameter κ. Thermokinetic simulations were conducted to estimate the impact of partial particle volatilization within the DASH-SP across a range of sampling conditions. Analyses of GF and RI data as a function of air mass origin, dry size, and altitude are reported, in addition to κ values for the inorganic and organic fractions of aerosol. Average RI values are found to be fairly constant (1.52-1.54) for all air mass categories. An algorithm is used to compare size-resolved DASH-SP GF with bulk scattering f(RH = 80%) data obtained from a pair of nephelometers, and the results show that the two can only be reconciled if GF is assumed to decrease with increasing dry size above 400 nm (i.e., beyond the upper bound of DASH-SP measurements). Individual case studies illustrate variations of hygroscopicity as a function of dry size, environmental conditions, altitude, and composition.

  2. Response of the climatic temperature to dust forcing, inferred from total ozone mapping spectrometer (TOMS) aerosol index and the NASA assimilation model

    NASA Astrophysics Data System (ADS)

    Alpert, P.; Herman, J.; Kaufman, Y. J.; Carmona, I.

    Recently, Alpert et al. (Alpert, P., Shay-El, Y., Kaufman, Y.J., Tanre, D., DaSilva, A., Schubert, S., Joseph, J.H., 1998. Quantification of dust-forced heating of the lower troposphere, Nature 395 (6700), 367-370, (24 September).) suggested an indirect measure of the tropospheric temperature response to dust aerosols by using model updates — roughly speaking model errors — of the NASA Goddard Earth Observing System version No. 1 (GEOS-1) data assimilation system. They have shown that these updates, which provide information about missing physical processes not included in the predictive model, have monthly mean patterns, which bear a striking similarity to patterns of dust over the Atlantic. This similarity in the number of dusty days was used to estimate the atmospheric response to dust. Here, the study is extended for all the major subtropical deserts over Africa and Asia using the total ozone mapping spectrometer (TOMS) aerosol index ( AI) for dust recently derived by Herman et al. (Herman, J.R., Bhartia, P.K., Torres, O., Hsu, C., Seftor, C., Celarier, E., 1997. Global distribution of UV-absorbing aerosols from Nimbus 7/TOMS data, J. Geophys. Res. 102, 16911-16922.). It is shown that the TOMS dust is highly correlated with the model errors with a maximum at the altitude of about 580 hPa and for the month of June with average correlation coefficient of 0.69 reaching up to 0.8 for specific months. In contrast to the previous study where only dust over ocean was employed, here, much higher dust concentrations are detected and the linear heating for weak dust becomes quickly saturated for AI above 1.5, then drops for very high values of AI that exceed about 3. This result is consistent with the theoretical predictions.

  3. Classification of Dust Days by Satellite Remotely Sensed Aerosol Products

    NASA Technical Reports Server (NTRS)

    Sorek-Hammer, M.; Cohen, A.; Levy, Robert C.; Ziv, B.; Broday, D. M.

    2013-01-01

    Considerable progress in satellite remote sensing (SRS) of dust particles has been seen in the last decade. From an environmental health perspective, such an event detection, after linking it to ground particulate matter (PM) concentrations, can proxy acute exposure to respirable particles of certain properties (i.e. size, composition, and toxicity). Being affected considerably by atmospheric dust, previous studies in the Eastern Mediterranean, and in Israel in particular, have focused on mechanistic and synoptic prediction, classification, and characterization of dust events. In particular, a scheme for identifying dust days (DD) in Israel based on ground PM10 (particulate matter of size smaller than 10 nm) measurements has been suggested, which has been validated by compositional analysis. This scheme requires information regarding ground PM10 levels, which is naturally limited in places with sparse ground-monitoring coverage. In such cases, SRS may be an efficient and cost-effective alternative to ground measurements. This work demonstrates a new model for identifying DD and non-DD (NDD) over Israel based on an integration of aerosol products from different satellite platforms (Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI)). Analysis of ground-monitoring data from 2007 to 2008 in southern Israel revealed 67 DD, with more than 88 percent occurring during winter and spring. A Classification and Regression Tree (CART) model that was applied to a database containing ground monitoring (the dependent variable) and SRS aerosol product (the independent variables) records revealed an optimal set of binary variables for the identification of DD. These variables are combinations of the following primary variables: the calendar month, ground-level relative humidity (RH), the aerosol optical depth (AOD) from MODIS, and the aerosol absorbing index (AAI) from OMI. A logistic regression that uses these variables, coded as binary

  4. Systematic aerosol characterization by combining GOME-2 UV Aerosol Indices with trace gas concentrations

    NASA Astrophysics Data System (ADS)

    Penning de Vries, M.; Stammes, P.; Wagner, T.

    2012-04-01

    The task of determining aerosol type using passive remote sensing instruments is a daunting one. First, because the variety in aerosol (optical) properties is very large; and second, because the effect of aerosols on the detected top-of-atmosphere reflectance spectrum is smooth and mostly featureless. In addition, spectrometers like GOME-2 have a coarse spatial resolution, which makes aerosol characterization even more difficult due to interferences with clouds. On account of these problems, we do not attempt to derive aerosol properties from single measurements: instead, we combine time series of UV Aerosol Index and trace gas concentrations to derive the dominating aerosol type for each season. Aside from the Index values and trace gas concentrations themselves, the correlation between UV Aerosol Indices (which are indicative of aerosol absorption) with NO2, HCHO, and CHOCHO columns - or absence of it - provides clues to the (main) source of the aerosols in the investigated region and time range. For example: a high correlation of HCHO and Absorbing Aerosol Index points to aerosols from biomass burning, highly correlated CHOCHO, HCHO, and SCattering Index indicate biogenic secondary organic aerosols, and coinciding high NO2 concentrations with high SCattering Index values are associated with industrial and urban aerosols. We here present case studies for several regions to demonstrate the suitability of our approach. Then, we introduce a method to systematically derive the dominating aerosol type on a global scale on time scales varying from monthly to yearly.

  5. Infrared spectroscopy of aerosols

    NASA Astrophysics Data System (ADS)

    Mentel, Th.; Sebald, H.

    2003-04-01

    In our large Aerosol Chamber at the FZ Jülich we apply HR FTIR absorption spectroscopy for the determination of trace gases. In the FTIR spectra we also observe broad absorptions of several 10 to a few 100 cm-1 widths that arise from species in the condensed aerosol phase: liquid H_2O, NO_3^-, SO_42-, HSO_4^-, or dicarboxylic acids. Moreover, the aerosol droplets caused extinctions over several 1000 cm-1 by IR scattering. This allows for in-situ observation of changes in the condensed aerosol phase e.g. on HNO_3 uptake, like the shift of the sulfate/bisulfate equilibrium or the growth by water condensation. The IR absorptions of the condensed aerosol phase provide useful extra information in process studies, if they can be quantified. Therefore the absorption cross section, respective, the absorption index which is the imaginary part of the complex refractive index is needed. We set up an aerosol flow tube in which IR spectroscopy on a 8 m light path and aerosol size distribution measurements in the range from 20 nm - 10 μm can be performed simultaneously. We measured sulfate aerosols at several relative humidities (dry, metastable, deliquescent). We will demonstrate an iterative procedure based on Mie calculations and Kramers Kronig transformation to retrieve the absorption index from the observed IR spectra and the corresponding size distribution (for dry ammonium sulfate). We will compare resulting absorption indices for aqueous sodium bisulfate aerosols at several relative humidties with thermodynamic model calculations for the Na^+/H^+/HSO_4^-/SO_42-/H_2O system.

  6. 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.

  7. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    acetate, polymerized rapidly and produced some polymer film encapsulation of the aerosol droplets. A two-stage microcapsule generator was designed...encapsulating material, the generator also produced microcapsules of dibutyl phosphite in polyethylene, nitrocellulose, and natural rubber.

  8. [Ease of use, feasibility and performance of ankle arm index measurement in patients with chronic leg ulcers. Study of 100 consecutive patients].

    PubMed

    Lazareth, I; Taieb, J C; Michon-Pasturel, U; Priollet, P

    2009-09-01

    International guidelines on leg ulcers recommend measuring the ankle arm index (AAI) to diagnose and assess peripheral arterial occlusive disease (PAOD) of the lower limbs. These guidelines do not, however, describe the method which should be used to make the measurement: which artery should be measured -in the event of an open leg ulcer, what are the practical difficulties for positioning the cuff- how well do patients tolerate the procedure? We conducted a prospective study focusing on ease of use, tolerance and performance of AAI measurements in patients with leg ulcers. In compliance with recent French guidelines, we measured the AAI for both distal leg arteries and retained the lowest value for analysis. Within a six-month study period, 100 consecutive inpatients with leg ulcers of various etiologies were studied. Mean age was 75, female predominance 60%, body mass index 27. Etiologies of leg ulcers were pure venous (29%), mixed venous predominant (17%), pure arterial (9%), mixed arterial predominant (8%), mixed (6%), hypertensive ulcers (11%), rare cause (8%), multifactorial (12%). Pain was present in 92%, with a VAS above 3 for 73%. Measurement of AAI was possible in 98% of patients. It was too painful and thus considered unethical for two patients with hypertensive ulcers. For the 98 patients measured, the ulcer had to be protected during the measurement in 76%. The measurement procedure only took five minutes for one leg, and was judged easy to perform by 93% of the operators. For the majority (76%) of patients, the measurement was not painful. We determined the diagnostic performance of AAI by comparing the results with those of arterial ultrasound in 90 patients who had a complete arterial ultrasound exploration of the legs. Compared with arterial ultrasound, the sensitivity of AAI<0.9 for detecting the presence of PAOD was 84.7%, with 97% specificity. PAOD was not diagnosed in any patient who had two palpable distal pulses and a normal AAI. Measurement

  9. Atmospheric aerosols: Their Optical Properties and Effects (supplement)

    NASA Technical Reports Server (NTRS)

    1976-01-01

    A digest of technical papers is presented. Topics include aerosol size distribution from spectral attenuation with scattering measurements; comparison of extinction and backscattering coefficients for measured and analytic stratospheric aerosol size distributions; using hybrid methods to solve problems in radiative transfer and in multiple scattering; blue moon phenomena; absorption refractive index of aerosols in the Denver pollution cloud; a two dimensional stratospheric model of the dispersion of aerosols from the Fuego volcanic eruption; the variation of the aerosol volume to light scattering coefficient; spectrophone in situ measurements of the absorption of visible light by aerosols; a reassessment of the Krakatoa volcanic turbidity, and multiple scattering in the sky radiance.

  10. A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances

    NASA Astrophysics Data System (ADS)

    Penning de Vries, M. J. M.; Beirle, S.; Hörmann, C.; Kaiser, J. W.; Stammes, P.; Tilstra, L. G.; Tuinder, O. N. E.; Wagner, T.

    2015-09-01

    Detecting the optical properties of aerosols using passive satellite-borne measurements alone is a difficult task due to the broadband effect of aerosols on the measured spectra and the influences of surface and cloud reflection. We present another approach to determine aerosol type, namely by studying the relationship of aerosol optical depth (AOD) with trace gas abundance, aerosol absorption, and mean aerosol size. Our new Global Aerosol Classification Algorithm, GACA, examines relationships between aerosol properties (AOD and extinction Ångström exponent from the Moderate Resolution Imaging Spectroradiometer (MODIS), UV Aerosol Index from the second Global Ozone Monitoring Experiment, GOME-2) and trace gas column densities (NO2, HCHO, SO2 from GOME-2, and CO from MOPITT, the Measurements of Pollution in the Troposphere instrument) on a monthly mean basis. First, aerosol types are separated based on size (Ångström exponent) and absorption (UV Aerosol Index), then the dominating sources are identified based on mean trace gas columns and their correlation with AOD. In this way, global maps of dominant aerosol type and main source type are constructed for each season and compared with maps of aerosol composition from the global MACC (Monitoring Atmospheric Composition and Climate) model. Although GACA cannot correctly characterize transported or mixed aerosols, GACA and MACC show good agreement regarding the global seasonal cycle, particularly for urban/industrial aerosols. The seasonal cycles of both aerosol type and source are also studied in more detail for selected 5° × 5° regions. Again, good agreement between GACA and MACC is found for all regions, but some systematic differences become apparent: the variability of aerosol composition (yearly and/or seasonal) is often not well captured by MACC, the amount of mineral dust outside of the dust belt appears to be overestimated, and the abundance of secondary organic aerosols is underestimated in comparison

  11. Global aerosol optical properties and application to Moderate Resolution Imaging Spectroradiometer aerosol retrieval over land

    NASA Astrophysics Data System (ADS)

    Levy, Robert C.; Remer, Lorraine A.; Dubovik, Oleg

    2007-07-01

    As more information about global aerosol properties has become available from remotely sensed retrievals and in situ measurements, it is prudent to evaluate this new information, both on its own and in the context of satellite retrieval algorithms. Using the climatology of almucantur retrievals from global Aerosol Robotic Network (AERONET) Sun photometer sites, we perform cluster analysis to determine aerosol type as a function of location and season. We find that three spherical-derived types (describing fine-sized dominated aerosol) and one spheroid-derived types (describing coarse-sized dominated aerosol, presumably dust) generally describe the range of AERONET observed global aerosol properties. The fine-dominated types are separated mainly by their single scattering albedo (ω0), ranging from nonabsorbing aerosol (ω0 ˜ 0.95) in developed urban/industrial regions, to moderately absorbing aerosol (ω0 ˜ 0.90) in forest fire burning and developing industrial regions, to absorbing aerosol (ω0 ˜ 0.85) in regions of savanna/grassland burning. We identify the dominant aerosol type at each site, and extrapolate to create seasonal 1° × 1° maps of expected aerosol types. Each aerosol type is bilognormal, with dynamic (function of optical depth) size parameters (radius, standard deviation, volume distribution) and complex refractive index. Not only are these parameters interesting in their own right, they can also be applied to aerosol retrieval algorithms, such as to aerosol retrieval over land from Moderate Resolution Imaging Spectroradiometer. Independent direct-Sun AERONET observations of spectral aerosol optical depth (τ) are consistent the spectral dependence of the models, indicating that our derived aerosol models are relevant.

  12. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, aerosols - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of aerosol particles per cubic meter of air.Atmospheric aerosols are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. Aerosol particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10

  13. Detailed Aerosol Characterization using Polarimetric Measurements

    NASA Astrophysics Data System (ADS)

    Hasekamp, Otto; di Noia, Antonio; Stap, Arjen; Rietjens, Jeroen; Smit, Martijn; van Harten, Gerard; Snik, Frans

    2016-04-01

    Anthropogenic aerosols are believed to cause the second most important anthropogenic forcing of climate change after greenhouse gases. In contrast to the climate effect of greenhouse gases, which is understood relatively well, the negative forcing (cooling effect) caused by aerosols represents the largest reported uncertainty in the most recent assessment of the International Panel on Climate Change (IPCC). To reduce the large uncertainty on the aerosol effects on cloud formation and climate, accurate satellite measurements of aerosol optical properties (optical thickness, single scattering albedo, phase function) and microphysical properties (size distribution, refractive index, shape) are essential. There is growing consensus in the aerosol remote sensing community that multi-angle measurements of intensity and polarization are essential to unambiguously determine all relevant aerosol properties. This presentations adresses the different aspects of polarimetric remote sensing of atmospheric aerosols, including retrieval algorithm development, validation, and data needs for climate and air quality applications. During past years, at SRON-Netherlands Instite for Space Research retrieval algorithms have been developed that make full use of the capabilities of polarimetric measurements. We will show results of detailed aerosol properties from ground-based- (groundSPEX), airborne- (NASA Research Scanning Polarimeter), and satellite (POLDER) measurements. Also we will discuss observational needs for future instrumentation in order to improve our understanding of the role of aerosols in climate change and air quality.

  14. Using OMI Observations to Measure Aerosol Absorption of Biomass Burning Aerosols Above Clouds

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, P. K.; Jethva, Hiren

    2011-01-01

    The presence of absorbing aerosol layers above clouds is unambiguously detected by the TOMS/OMI UV Aerosol Index (AI) that uses satellite observations at two near-UV channels. A sensitivity study using radiative transfer calculations shows that the AI signal of resulting from the presence of aerosols above clouds is mainly driven by the aerosol absorption optical depth and the optical depth of the underlying cloud. Based on these results, an inversion algorithm has been developed to retrieve the aerosol optical depth (AOD) of aerosol layers above clouds. In this presentation we will discuss the sensitivity analysis, describe the retrieval approach, and present results of applications of the retrieval method to OMI observations over the South Atlantic Ocean. Preliminary error analyses, to be discussed, indicate that the AOD can be underestimated (up to -30%) or overestimated (up to 60%) depending on algorithmic assumptions.

  15. Ankle-Arm Index, Angiography, and Duplex Ultrasonography After Recanalization of Occlusions in Femoropopliteal Arteries: Comparison of Long-Term Results

    SciTech Connect

    Winter-Warnars, Hillegonda A.O.; Graaf, Yolanda van der; Mali, Willem P.T.M.

    1996-04-15

    Purpose: Comparison of the relative values of the ankle-arm index (AAI) at rest and after exercise, angiography, and duplex ultrasonography for the follow-up of percutaneous transluminal angioplasty (PTA) in patients with peripheral vascular disease. Methods: Thirty-two patients were prospectively followed after technically and clinically successful PTA of a femoropopliteal occlusion. The patency of the femoropopliteal artery was assessed for 1 year using AAI measurements at rest and after exercise; duplex ultrasonography at 4, 12, 24, 36, and 52 weeks; and angiography at 3 and 12 months after PTA. Results: Patency was highly dependent on the measurement technique. The cumulative patency after 1 year determined with the AAI at rest and during exercise, by angiography, and by duplex ultrasonography was 74%, 19%, 31%, and 32%, respectively. Seventy-five percent of the restenoses occurred at the site of the treated occlusion. Conclusion: Duplex ultrasonography is most suitable for this assessment, as it causes no patient discomfort and the specificity is better than AAI after exercise because vascular disease in other, proximal segments does not interfere with the results.

  16. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    materials determine the range of applicability of each method. A useful microencapsulation method, based on coagulation by inertial force was developed...The generation apparatus, consisting of two aerosol generators in series, was utilized to produce many kinds of microcapsules . A fluid energy mill...was found useful for the production of some microcapsules . The permeability of microcapsule films and the effect of exposure time and humidity were

  17. Type of Aerosols Determination Over Malaysia by AERONET Data

    NASA Astrophysics Data System (ADS)

    Lim, H.; Tan, F.; Abdullah, K.; Holben, B. N.

    2013-12-01

    Aerosols are one of the most interesting studies by the researchers due to the complicated of their characteristic and are not yet well quantified. Besides that there still have huge uncertainties associated with changes in Earth's radiation budget. The previous study by other researchers shown a lot of difficulties and challenges in quantifying aerosol influences arise. As well as the heterogeneity from the aerosol loading and properties: spatial, temporal, size, and composition. In this study, we were investigated the aerosol characteristics over two regions with different environmental conditions and aerosol sources contributed. The study sites are Penang and Kuching, Malaysia where ground-based AErosol RObotic NETwork (AERONET) sun-photometer was deployed. The types of the aerosols for both study sites were identified by analyzing aerosol optical depth, angstrom parameter and spectral de-convolution algorithm product from sun-photometer. The analysis was carried out associated with the in-situ meteorological data of relative humidity, visibility and air pollution index. The major aerosol type over Penang found in this study was hydrophobic aerosols. Whereas the hydrophilic type of the aerosols was highly distributed in Kuching. The major aerosol size distributions for both regions were identified in this study. The result also shows that the aerosol optical properties were affected by the types and characteristic of aerosols. Therefore, in this study we generated an algorithm to determine the aerosols in Malaysia by considered the environmental factors. From this study we found that the source of aerosols should always being consider in to retrieve the accurate information of aerosol for air quality study.

  18. Aerosol physical properties from satellite horizon inversion

    NASA Technical Reports Server (NTRS)

    Gray, C. R.; Malchow, H. L.; Merritt, D. C.; Var, R. E.; Whitney, C. K.

    1973-01-01

    The feasibility is investigated of determining the physical properties of aerosols globally in the altitude region of 10 to 100 km from a satellite horizon scanning experiment. The investigation utilizes a horizon inversion technique previously developed and extended. Aerosol physical properties such as number density, size distribution, and the real and imaginary components of the index of refraction are demonstrated to be invertible in the aerosol size ranges (0.01-0.1 microns), (0.1-1.0 microns), (1.0-10 microns). Extensions of previously developed radiative transfer models and recursive inversion algorithms are displayed.

  19. Optical Absorption Characteristics of Aerosols.

    DTIC Science & Technology

    1985-09-11

    properties of the powder as well as the thickness of the layer. For a layer that is thick enough so that no light is transmitted, the Kubelka -- Munk theory...which is a two stream radiative transfer model, relates the reflectance to the ratio of the absorption to the scattering. The Kubelka - Munk theory has...of the aerosol material is known. Under the assumptions of the Kubelka - Munk . theory, the imaginary component of the refractive index is deter- mined

  20. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

  1. Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: an AQMEII-2 perspective

    EPA Science Inventory

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model in...

  2. Aerosol Transmission of Filoviruses

    PubMed Central

    Mekibib, Berhanu; Ariën, Kevin K.

    2016-01-01

    Filoviruses have become a worldwide public health concern because of their potential for introductions into non-endemic countries through international travel and the international transport of infected animals or animal products. Since it was first identified in 1976, in the Democratic Republic of Congo (formerly Zaire) and Sudan, the 2013–2015 western African Ebola virus disease (EVD) outbreak is the largest, both by number of cases and geographical extension, and deadliest, recorded so far in medical history. The source of ebolaviruses for human index case(s) in most outbreaks is presumptively associated with handling of bush meat or contact with fruit bats. Transmission among humans occurs easily when a person comes in contact with contaminated body fluids of patients, but our understanding of other transmission routes is still fragmentary. This review deals with the controversial issue of aerosol transmission of filoviruses. PMID:27223296

  3. Aerosol gels

    NASA Technical Reports Server (NTRS)

    Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

    2010-01-01

    An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

  4. A review of atmospheric aerosol measurements

    NASA Astrophysics Data System (ADS)

    McMurry, Peter H.

    Recent developments in atmospheric aerosol measurements are reviewed. The topics included complement those covered in the recent review by Chow (JAWMA 45: 320-382, 1995) which focuses on regulatory compliance measurements and filter measurements of particulate composition. This review focuses on measurements of aerosol integral properties (total number concentration, CCN concentration, optical coefficients, etc.), aerosol physical chemical properties (density, refractive index, equilibrium water content, etc.), measurements of aerosol size distributions, and measurements of size-resolved aerosol composition. Such measurements play an essential role in studies of secondary aerosol formation by atmospheric chemical transformations and enable one to quantify the contributions of various species to effects including light scattering/absorption, health effects, dry deposition, etc. Aerosol measurement evolved from an art to a science in the 1970s following the development of instrumentation to generate monodisperse calibration aerosols of known size, composition, and concentration. While such calibration tools permit precise assessments of instrument responses to known laboratory-generated aerosols, unquantifiable uncertainties remain even when carefully calibrated instruments are used for atmospheric measurements. This is because instrument responses typically depend on aerosol properties including composition, shape, density, etc., which, for atmospheric aerosols, may vary from particle-to-particle and are often unknown. More effort needs to be made to quantify measurement accuracies that can be achieved for realistic atmospheric sampling scenarios. The measurement of organic species in atmospheric particles requires substantial development. Atmospheric aerosols typically include hundreds of organic compounds, and only a small fraction (˜10%) of these can be identified by state-of-the-art analytical methodologies. Even the measurement of the total particulate organic

  5. Statistical characteristics of atmospheric aerosol as determined from AERONET measurements

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Kokhanovsky, Alexander

    2015-04-01

    Seasonal means and standard deviations of column-integrated aerosol optical properties (e.g. spectral aerosol optical thickness (AOT), single scattering albedo, phase function, Ångström exponent, volume particle size distribution, complex refractive index, absorbing aerosol optical thickness) from several Aerosol Robotic Network (AERONET) sites located in typical aerosol source and background regions are investigated (Holben et al., 1998). The AERONET program is an inclusive network of ground-based sun-photometers that measure atmospheric aerosol optical properties (http://aeronet.gsfc.nasa.gov/). The results can be used for improving the accuracy of satellite-retrieved AOT, assessments of the global aerosol models, studies of atmospheric pollution and aerosol radiative forcing on climate. We have paid a special attention to several AERONET sites that are Mexico_City (Mexico), Alta_Floresta (Brazil), Avignon (France), Solar_Village (Saudi Arabia), and Midway_Island (Pacific) representative for industrial/urban, biomass burning, rural, desert dust and oceanic aerosols, respectively. We have found that the optical and microphysical aerosol properties are highly dependent on the local aerosol emission sources and seasonal meteorological conditions.

  6. Implementation of the Missing Aerosol Physics into LLNL IMPACT

    SciTech Connect

    Chuang, C

    2005-02-09

    characteristics and composition of aerosols. These processes, together with other physical properties (i.e., size, density, and refractive index), determine the atmospheric lifetime of aerosols and their radiative forcing. To better represent physical properties of aerosols, we adapted an aerosol microphysics model that simulates aerosol size distribution. Work toward this goal was done in collaboration with Professor Anthony Wexler of University of California at Davis. Professor Wexler's group has developed sectional models of atmospheric aerosol dynamics that include an arbitrary number of size sections and chemical compounds or compound classes. The model, AIM (Aerosol Inorganic Model), is designed to predict the mass distribution and composition of urban and regional particulate matter (''Sun and Wexler'', 1998a, b). This model is currently incorporated into EPA's Models-3 air quality modeling platform/CMAQ (Community Multiscale Air Quality) to test its performance with previous simulations of CMAQ over the continental US.

  7. Humidity Dependent Extinction of Clay Aerosols

    NASA Astrophysics Data System (ADS)

    Greenslade, M. E.; Attwood, A. R.

    2010-12-01

    Aerosols play an important role in the Earth’s radiative balance by directly scattering and absorbing radiation. The magnitude of aerosol forcing can be altered by changes in relative humidity which cause aerosol size, shape and refractive index to vary. To quantify these effects, a custom cavity ring down instrument operated at 532 nm with two sample channels measures aerosols extinction under dry conditions and at elevated humidity. The optical growth, fRH(ext), is determined as a ratio of the extinction cross section at high relative humidity to that under dry conditions. Three key clay components of mineral dust and mixtures of clay components with ammonium sulfate are investigated using this method. Experimentally obtained optical growth is compared with physical growth factors from the literature and our work determined using several different techniques. Further, Mie theory calculations based on published optical constants are compared with experimental results. Differences between theory and experiment will be discussed.

  8. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  9. The effect of aerosols on the earth-atmosphere albedo

    NASA Technical Reports Server (NTRS)

    Herman, B. M.; Browning, S. R.

    1975-01-01

    The paper presents calculations of the change in reflected flux by the earth-atmosphere system in response to increases in the atmospheric aerosol loading for a range of complex indices of refraction, solar elevation angle and ground albedo. Results show that, for small values of ground albedo, the reflected solar flux may either increase or decrease with increasing aerosol loadings, depending upon the complex part of the index of refraction of the aerosols. For high ground albedos, an increase in aerosol levels always results in a decrease of reflected flux (i.e., a warming of the earth-atmosphere system).

  10. Mass absorption indices of various types of natural aerosol particles in the infrared.

    PubMed

    Fischer, K

    1975-12-01

    The mass absorption index of aerosol particles has been measured in the 2-17-microm wavelength region. The measurements were performed on films of aerosol particles that were collected by an automatic jet impactor at polluted and various uncontaminated remote sites. All but marine aerosols possess strong absorption bands in the transparent part of the atmospheric long-wave spectrum, indicating marked influence of aerosol particles on the radiation budget of the atmosphere.

  11. Information Content of Aerosol Retrievals in the Sunglint Region

    NASA Technical Reports Server (NTRS)

    Ottaviani, M.; Knobelspiesse, K.; Cairns, B.; Mishchenko, M.

    2013-01-01

    We exploit quantitative metrics to investigate the information content in retrievals of atmospheric aerosol parameters (with a focus on single-scattering albedo), contained in multi-angle and multi-spectral measurements with sufficient dynamical range in the sunglint region. The simulations are performed for two classes of maritime aerosols with optical and microphysical properties compiled from measurements of the Aerosol Robotic Network. The information content is assessed using the inverse formalism and is compared to that deriving from observations not affected by sunglint. We find that there indeed is additional information in measurements containing sunglint, not just for single-scattering albedo, but also for aerosol optical thickness and the complex refractive index of the fine aerosol size mode, although the amount of additional information varies with aerosol type.

  12. Improving Aerosol and Visibility Forecasting Capabilities Using Current and Future Generations of Satellite Observations

    DTIC Science & Technology

    2015-08-27

    Orthogonal Polarization (CALIOP) aerosol and cloud layer products, as well as collocated Ozone Monitoring Instrument (OMI) Aerosol Index (Al) data and...radiance assimilation capability by: 1) improving forecast performance over cloudy regions using the Ozone Monitoring Instrument (OMI) Aerosol Index...only CALIOP layer products. Both OMI-MODIS and CALIOP-based daytime spatial distributions of ACA events show similar patterns during both periods

  13. 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.

  14. AEROSOL AND GAS MEASUREMENT

    EPA Science Inventory

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  15. Does the Madden-Julian Oscillation influence aerosol variability?

    NASA Astrophysics Data System (ADS)

    Tian, Baijun; Waliser, Duane E.; Kahn, Ralph A.; Li, Qinbin; Yung, Yuk L.; Tyranowski, Tomasz; Geogdzhayev, Igor V.; Mishchenko, Michael I.; Torres, Omar; Smirnov, Alexander

    2008-06-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using multiple, global satellite aerosol products: aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite MJO analysis indicates that large variations in the TOMS AI and MODIS/AVHRR AOT are found over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is weak but the background aerosol level is high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The MODIS/AVHRR pattern is consistent with ground-based Aerosol Robotic Network data. These results indicate that the MJO and its associated cloudiness, rainfall, and circulation variability systematically influence the variability in remote sensing aerosol retrieval results. Several physical and retrieval algorithmic factors that may contribute to the observed aerosol-rainfall relationships are discussed. Preliminary analysis indicates that cloud contamination in the aerosol retrievals is likely to be a major contributor to the observed relationships, although we cannot exclude possible contributions from other physical mechanisms. Future research is needed to fully understand these complex aerosol-rainfall relationships.

  16. Solar geoengineering using solid aerosol in the stratosphere

    NASA Astrophysics Data System (ADS)

    Weisenstein, D. K.; Keith, D. W.; Dykema, J. A.

    2015-10-01

    Solid aerosol particles have long been proposed as an alternative to sulfate aerosols for solar geoengineering. Any solid aerosol introduced into the stratosphere would be subject to coagulation with itself, producing fractal aggregates, and with the natural sulfate aerosol, producing liquid-coated solids. Solid aerosols that are coated with sulfate and/or have formed aggregates may have very different scattering properties and chemical behavior than uncoated non-aggregated monomers do. We use a two-dimensional (2-D) chemistry-transport-aerosol model to capture the dynamics of interacting solid and liquid aerosols in the stratosphere. As an example, we apply the model to the possible use of alumina and diamond particles for solar geoengineering. For 240 nm radius alumina particles, for example, an injection rate of 4 Tg yr-1 produces a global-average shortwave radiative forcing of -1.2 W m-2 and minimal self-coagulation of alumina although almost all alumina outside the tropics is coated with sulfate. For the same radiative forcing, these solid aerosols can produce less ozone loss, less stratospheric heating, and less forward scattering than sulfate aerosols do. Our results suggest that appropriately sized alumina, diamond or similar high-index particles may have less severe technology-specific risks than sulfate aerosols do. These results, particularly the ozone response, are subject to large uncertainties due to the limited data on the rate constants of reactions on the dry surfaces.

  17. Absorption characteristics of aerosols over the northwestern region of India: Distinct seasonal signatures of biomass burning aerosols and mineral dust

    NASA Astrophysics Data System (ADS)

    Gogoi, Mukunda M.; Suresh Babu, S.; Krishna Moorthy, K.; Manoj, M. R.; Chaubey, Jai Prakash

    2013-07-01

    Continuous measurements of aerosol black carbon (BC) mass concentrations made over a period of 3 years from a semi-arid, near-coastal, remote and sparsely inhabited location along with satellite-based data of aerosol absorption index, optical depth and extinction profiles in western India are used to characterize the distinct nature of aerosols near the surface and in the free troposphere and their seasonality. Despite being far remote and sparsely inhabited, significant levels of BC are observed in the ambient during winter (1.45 ± 0.71 μg m-3) attributed to biomass burning aerosols, advected to the site from the north and west; while during summer the concentrations are far reduced (0.23 ± 0.11 μg m-3) and represent the apparent background concentrations. The spectral absorption coefficients suggest the BC during summer be mostly of fossil fuel combustions. The strong convective boundary layer dynamics produces significant diurnal variation during winter and modulates to a lesser extent the seasonal variation. Examination of aerosol (absorption) index from OMI data for the study period showed a seasonal pattern that is almost opposite to that seen at the surface; with high aerosol index in summer, showing a significant difference between the surface and columnar aerosol types in summer. MISR and MODIS-derived columnar AOD follow the OMI pattern. Analysis of the vertical profiles of aerosol extinction and volume depolarization ratio (VDR), derived from CALIPSO data indicates the presence of strong dust layers with VDR ˜ 0.3 in the altitude region 4-6 km, contributing to the high aerosol index in the OMI data, while the surface measurements show absorptive properties representing fossil fuel BC aerosols.

  18. Aerosol distribution apparatus

    DOEpatents

    Hanson, W.D.

    An apparatus for uniformly distributing an aerosol to a plurality of filters mounted in a plenum, wherein the aerosol and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous aerosol-testing of all the filters in the plenum.

  19. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  20. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  1. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  2. Airborne Aerosol Closure Studies During PRIDE

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

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

  3. Aerosol algorithm evaluation within aerosol-CCI

    NASA Astrophysics Data System (ADS)

    Kinne, Stefan; Schulz, Michael; Griesfeller, Jan

    Properties of aerosol retrievals from space are difficult. Even data from dedicated satellite sensors face contaminations which limit the accuracy of aerosol retrieval products. Issues are the identification of complete cloud-free scenes, the need to assume aerosol compositional features in an underdetermined solution space and the requirement to characterize the background at high accuracy. Usually the development of aerosol is a slow process, requiring continuous feedback from evaluations. To demonstrate maturity, these evaluations need to cover different regions and seasons and many different aerosol properties, because aerosol composition is quite diverse and highly variable in space and time, as atmospheric aerosol lifetimes are only a few days. Three years ago the ESA Climate Change Initiative started to support aerosol retrieval efforts in order to develop aerosol retrieval products for the climate community from underutilized ESA satellite sensors. The initial focus was on retrievals of AOD (a measure for the atmospheric column amount) and of Angstrom (a proxy for aerosol size) from the ATSR and MERIS sensors on ENVISAT. The goal was to offer retrieval products that are comparable or better in accuracy than commonly used NASA products of MODIS or MISR. Fortunately, accurate reference data of ground based sun-/sky-photometry networks exist. Thus, retrieval assessments could and were conducted independently by different evaluation groups. Here, results of these evaluations for the year 2008 are summarized. The capability of these newly developed retrievals is analyzed and quantified in scores. These scores allowed a ranking of competing efforts and also allow skill comparisons of these new retrievals against existing and commonly used retrievals.

  4. Sun photometer aerosol retrievals during SALTRACE

    NASA Astrophysics Data System (ADS)

    Toledano, Carlos; Torres, Benjamin; Althausen, Dietrich; Groß, Silke; Freudenthaler, Volker; Weinzierl, Bernadett; Gasteiger, Josef; Ansmann, Albert; Wiegner, Matthias; González, Ramiro; Cachorro, Victoria

    2015-04-01

    The Saharan Aerosol Long-range Transport and Aerosol-Cloud-Interaction Experiment (SALTRACE), aims at investigating the long-range transport of Saharan dust across the Atlantic Ocean. A large set of ground-based and airborne aerosol and meteorological instrumentation was used for this purpose during a 5-week campaign that took place during June-July 2013. Several Sun photometers were deployed at Barbados Island during this campaign. Two Cimels included in AERONET and the Sun and Sky Automatic Radiometer (SSARA) were co-located with the ground-based lidars BERTHA and POLIS. A set of optical and microphysical aerosol properties derived from Sun and Sky spectral observations (principal plane and almucantar configurations) in the range 340-1640nm are analyzed, including aerosol optical depth (AOD), volume size distribution, complex refractive index, sphericity and single scattering albedo. The Sun photometers include polarization capabilities, therefore apart from the inversion of sky radiances as it is routinely done in AERONET, polarized radiances are also inverted. Several dust events are clearly identified in the measurement period, with moderated AOD (500nm) in the range 0.3 to 0.6. The clean marine background was also observed during short periods. The retrieved aerosol properties are compared with the lidar and in-situ observations carried out within SALTRACE, as well as with data collected during the SAMUM campaigns in Morocco and Cape Verde, in order to investigate possible changes in the dust plume during the transport.

  5. Polarimetric Remote Sensing of Atmospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Hasekamp, O. P.; Stap, A.; di Noia, A.; Rietjens, J.; Smit, M.; van Harten, G.; Snik, F.

    2014-12-01

    To reduce the large uncertainty on the aerosol effects on cloud formation and climate, accurate satellite measurements of aerosol optical properties (optical thickness, single scattering albedo, phase function) and microphysical properties (size distribution, refractive index, shape) are essential. Satellite instruments that perform multi-angle photopolarimetric measurements have the capability to provide these aerosol properties with sufficient accuracy. The only satellite instrument that provided a multi-year data set of multi-angle photopolarimetric measurements is the POLDER-3 instrument onboard the PARASOL microsatellite that operated between 2005-2013. PARASOL provides measurements of a ground scene under (up to) 16 viewing geometries in 9 spectral bands (3 for polarization). In order to make full use of the capability of PARASOL measurements of intensity and polarization properties of reflected light at multiple viewing angles and multiple wavelengths, we developed a retrieval algorithm that considers a continuous parameter space for aerosol microphysical properties (size distribution and refractive index) and properly accounts for land or ocean reflection by retrieving land and ocean parameters simultaneously with aerosol properties. Here, we present the key aspects of our PARASOL retrievals (inverse method, forward model, information content, cloud screening, computational aspects) as well as a validation of retrieved aerosol properties with ground-based measurements of the AERONET network. Also, we discuss required improvements for the next generation of polarimetric instruments dedicated to aerosol remote sensing and introduce a new spectropolarimetric instrument named SPEX. We will demonstrate the capabilities of SPEX based on ground based field measurements and characterization measurements in the labatory.

  6. Characterization of Spectral Absorption Properties of Aerosols Using Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.; Ahn, C.

    2012-01-01

    The wavelength-dependence of aerosol absorption optical depth (AAOD) is generally represented in terms of the Angstrom Absorption Exponent (AAE), a parameter that describes the dependence of AAOD with wavelength. The AAE parameter is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses high spectral resolution measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measured reflectance (rho lambda) is approximately given by Beer's law rho lambda = rho (sub 0 lambda) e (exp -mtau (sub abs lambda)) where rho(sub 0 lambda) is the cloud reflectance, m is the geometric slant path and tau (sub abs lambda) is the spectral AAOD. The rho (sub 0 lambda) term is determined by means of radiative transfer calculations using as input the cloud optical depth derived as described in Torres et al. [JAS, 2012] that accounts for the effects of aerosol absorption. In the second step, corrections for molecular and aerosol scattering effects are applied to the cloud reflectance term, and the spectral AAOD is then derived by inverting the equation above. The proposed technique will be discussed in detail and application results will be presented. The technique can be easily applied to hyper-spectral satellite measurements that include UV such as OMI, GOME and SCIAMACHY, or to multi-spectral visible measurements by other sensors provided that the aerosol-above-cloud events are easily identified.

  7. Aerosol Correction for Improving OMPS/LP Ozone Retrieval

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

  8. Development the EarthCARE aerosol classification scheme

    NASA Astrophysics Data System (ADS)

    Wandinger, Ulla; Baars, Holger; Hünerbein, Anja; Donovan, Dave; van Zadelhoff, Gerd-Jan; Fischer, Jürgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias

    2015-04-01

    the consistency of EarthCARE retrievals, to support aerosol description in the EarthCARE simulator ECSIM, and to facilitate a uniform specification of broad-band aerosol optical properties, a hybrid end-to-end aerosol classification model (HETEAC) is developed which serves as a baseline for EarthCARE algorithm development and evaluation procedures. The model's theoretical description of aerosol microphysics (bi-modal size distribution, spectral refractive index, and particle shape distribution) is adjusted to experimental data of aerosol optical properties, i.e. lidar ratio, depolarization ratio, Ångström exponents (hybrid approach). The experimental basis is provided by ground-based observations with sophisticated multi-wavelength, polarization lidars applied in the European Aerosol Research Lidar Network (EARLINET) and in dedicated field campaigns in the Sahara (SAMUM-1), Cape Verde (SAMUM-2), Barbados (SALTRACE), Atlantic Ocean (Polarstern and Meteor cruises), and Amazonia. The model is designed such that it covers the entire loop from aerosol microphysics via aerosol classification to optical and radiative properties of the respective types and allows consistency checks of modeled and measured parameters (end-to-end approach). Optical modeling considers scattering properties of spherical and non-spherical particles. A suitable set of aerosol types is defined which includes dust, clean marine, clean continental, pollution, smoke, and stratospheric aerosol. Mixtures of these types are included as well. The definition is consistent with CALIPSO approaches and will thus enable the establishment of a long-term global four-dimensional aerosol dataset.

  9. Author Indexing.

    ERIC Educational Resources Information Center

    Diodato, Virgil P.

    1981-01-01

    Discusses the effectiveness of using author-supplied indexing to increase subject control in information retrieval, and describes a study which compared author indexing for articles published in "American Mathematical Society" journals to indexing of the same articles by an editor of "Mathematical Reviews." Nine references are…

  10. The investigation of advanced remote sensing techniques for the measurement of aerosol characteristics

    NASA Technical Reports Server (NTRS)

    Deepak, A.; Becher, J.

    1979-01-01

    Advanced remote sensing techniques and inversion methods for the measurement of characteristics of aerosol and gaseous species in the atmosphere were investigated. Of particular interest were the physical and chemical properties of aerosols, such as their size distribution, number concentration, and complex refractive index, and the vertical distribution of these properties on a local as well as global scale. Remote sensing techniques for monitoring of tropospheric aerosols were developed as well as satellite monitoring of upper tropospheric and stratospheric aerosols. Computer programs were developed for solving multiple scattering and radiative transfer problems, as well as inversion/retrieval problems. A necessary aspect of these efforts was to develop models of aerosol properties.

  11. Does the Madden-Julian Oscillation Influence Aerosol Variability?

    NASA Astrophysics Data System (ADS)

    Tian, B.; Waliser, D. E.; Kahn, R. A.; Li, Q.; Yung, Y. L.; Tyranowski, T.; Geogdzhayev, I. V.; Mishchenko, M. I.; Torres, O.; Smirnov, A.

    2007-12-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using satellite-based global aerosol products, including aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite analysis is performed for boreal winter, and the global pentad rainfall data from the NOAA Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) are used to identify MJO events. The MJO composites exhibit large variations in the TOMS AI and MODIS/AVHRR AOT over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is relatively weak but the background aerosol level is relatively high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The Aerosol Robotic Network AOT pattern at Kaashidoo (73.5°E, 4.9°N) and Nauru (167°E, 0.5°S) is more consistent with MODIS and AVHRR. These results indicate a connection between the MJO, its associated rainfall and circulation variability, and the observed aerosol variations. Several physical and non-physical factors that may contribute to the observed aerosol-rainfall relationship, such as aerosol humidification effect, wet deposition, surface wind speed, phytoplankton, different sensor sensitivities (absorbing versus non-absorbing aerosols and upper versus lower tropospheric aerosols), sampling issue, and cloud contamination, are discussed. However, a clear causal explanation for the observed patterns remains elusive. Further investigation is needed to unravel this complex aerosol-rainfall relationship.

  12. Retrieval of Aerosol Absorption Properties from Satellite Observations

    NASA Technical Reports Server (NTRS)

    Torres, Omar; Bhartia, Pawan K.; Jethva, H.; Ahn, Chang-Woo

    2012-01-01

    The Angstrom Absorption Exponent (AAE) is a parameter commonly used to characterize the wavelength-dependence of aerosol absorption optical depth (AAOD). It is closely related to aerosol composition. Black carbon (BC) containing aerosols yield AAE values near unity whereas Organic carbon (OC) aerosol particles are associated with values larger than 2. Even larger AAE values have been reported for desert dust aerosol particles. Knowledge of spectral AAOD is necessary for the calculation of direct radiative forcing effect of aerosols and for inferring aerosol composition. We have developed a satellitebased method of determining the spectral AAOD of absorbing aerosols. The technique uses multi-spectral measurements of upwelling radiation from scenes where absorbing aerosols lie above clouds as indicated by the UV Aerosol Index. For those conditions, the satellite measurement can be explained, using an approximations of Beer's Law (BL), as the upwelling reflectance at the cloud top attenuated by the absorption effects of the overlying aerosol layer. The upwelling reflectance at the cloud-top in an aerosol-free atmospheric column is mainly a function of cloud optical depth (COD). In the proposed method of AAE derivation, the first step is determining COD which is retrieved using a previously developed color-ratio based approach. In the second step, corrections for molecular scattering effects are applied to both the observed ad the calculated cloud reflectance terms, and the spectral AAOD is then derived by an inversion of the BL approximation. The proposed technique will be discussed in detail and application results making use of OMI multi-spectral measurements in the UV-Vis. will be presented.

  13. Microphysical, chemical and optical aerosol properties in the Baltic Sea region

    NASA Astrophysics Data System (ADS)

    Kikas, Ülle; Reinart, Aivo; Pugatshova, Anna; Tamm, Eduard; Ulevicius, Vidmantas

    2008-11-01

    The microphysical structure, chemical composition and prehistory of aerosol are related to the aerosol optical properties and radiative effect in the UV spectral range. The aim of this work is the statistical mapping of typical aerosol scenarios and adjustment of regional aerosol parameters. The investigation is based on the in situ measurements in Preila (55.55° N, 21.00° E), Lithuania, and the AERONET data from the Gustav Dalen Tower (58 N, 17 E), Sweden. Clustering of multiple characteristics enabled to distinguish three aerosol types for clear-sky periods: 1) clean maritime-continental aerosol; 2) moderately polluted maritime-continental aerosol; 3) polluted continental aerosol. Differences between these types are due to significant differences in aerosol number and volume concentration, effective radius of volume distribution, content of SO 4- ions and Black Carbon, as well as different vertical profiles of atmospheric relative humidity. The UV extinction, aerosol optical depth (AOD) and the Ångstrom coefficient α increased with the increasing pollution. The value α = 1.96 was observed in the polluted continental aerosol that has passed over central and eastern Europe and southern Russia. Reduction of the clear-sky UV index against the aerosol-free atmosphere was of 4.5%, 27% and 41% for the aerosol types 1, 2 and 3, respectively.

  14. Overview of Aerosol Distribution

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram

    2005-01-01

    Our knowledge of atmospheric aerosols (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global aerosol system is fundamental for progress in climate change and hydrological cycle research. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global aerosol system. This complexity of the aerosol problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of aerosols, distinguishing natural from anthropogenic aerosol and measuring their interaction with clouds and climate. I shall discuss these topics and application of the data to air quality monitoring.

  15. Aerosol, radiation, and climate

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1983-01-01

    Airborne, spaceborne, and ground-based measurements are used to study the radiative and climatic effects of aerosols. The data, which are modelled with a hierarchy of radiation and climate models, and their implications are summarized. Consideration is given to volcanic aerosols, polar stratospheric clouds, and the Arctic haze. It is shown that several types of aerosols (volcanic particles and the Arctic haze) cause significant alterations to the radiation budget of the regions where they are located.

  16. 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.

  17. Aerosol particle microphotography and glare-spot absorption spectroscopy.

    PubMed

    Arnold, S; Holler, S; Li, J H; Serpengüzel, A; Auffermann, W F; Hill, S C

    1995-04-01

    The relative intensities of glare spots in the image of an electrodynamically trapped aerosol droplet are measured experimentally with an aerosol particle microscope and calculated theoretically. The theoretical calculations are in good agreement with these experiments and indicate that the intensities of these spots are extremely sensitive to the imaginary part of the refractive index. Experimentally, we obtain the molecular absorption spectrum of an impurity within a droplet by recording the spectrum of an individual glare spot produced by broadband illumination.

  18. Comparative Study of Aerosol and Cloud Detected by CALIPSO and OMI

    NASA Technical Reports Server (NTRS)

    Chen, Zhong; Torres, Omar; McCormick, M. Patrick; Smith, William; Ahn, Changwoo

    2012-01-01

    The Ozone Monitoring Instrument (OMI) on the Aura Satellite detects the presence of desert dust and smoke particles (also known as aerosols) in terms of a parameter known as the UV Aerosol Index (UV AI). The Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission measures the vertical distribution of aerosols and clouds. Aerosols and clouds play important roles in the atmosphere and climate system. Accurately detecting their presence, altitude, and properties using satellite radiance measurements is a very important task. This paper presents a comparative analysis of the CALIPSO Version 2 Vertical Feature Mask (VFM) product with the (OMI) UV Aerosol Index (UV AI) and reflectivity datasets for a full year of 2007. The comparison is done at regional and global scales. Based on CALIPSO arid OMI observations, the vertical and horizontal extent of clouds and aerosols are determined and the effects of aerosol type selection, load, cloud fraction on aerosol identification are discussed. It was found that the spatial-temporal correlation found between CALIPSO and OMI observations, is strongly dependent on aerosol types and cloud contamination. CALIPSO is more sensitivity to cloud and often misidentifies desert dust aerosols as cloud, while some small scale aerosol layers as well as some pollution aerosols are unidentified by OMI UV AI. Large differences in aerosol distribution patterns between CALIPSO and OMI are observed, especially for the smoke and pollution aerosol dominated areas. In addition, the results found a significant correlation between CALIPSO lidar 1064 nm backscatter and the OMI UV AI over the study regions.

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

    NASA Technical Reports Server (NTRS)

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

    1977-01-01

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

  20. A comparison between aerosol properties and air pollutants

    NASA Astrophysics Data System (ADS)

    Mukai, S.; Sano, I.; Nishimori, A.; Sato, M.

    A comparison between aerosol properties and air pollutants over urban cities in Japan S. Mukai, I. Sano, A. Nishimori and M. Sato Kinki University For understanding urban aerosols, sun/sky photometry and polarimetry with PSR-1000 (Opto. Research) have been undertaken over Higashi-Osaka since 1996. Multi-spectral photometers CE-318 (Cimel Electronique) and POM-100P (Prede Co.) are set up later for an AERONET site and a SKYNET site, respectively. Radiometers provide us with the optical thickness of aerosols and Ångström exponent. Another aerosol properties, e.g., size distribution, refractive index, etc., are retrieved based on the inversion method. Higashi-Osaka, which means east side of Osaka, is an industrial city located between Osaka bay and Mt.Ikoma. Anthropogenic aerosols produced by industrial activity and oceanic aerosols flying from Osaka bay are mixed together and trapped just around our site due to reflection from Mt.Ikoma. Therefore our city is famous for heavy air pollution, and aerosols here have a complicated feature mixing with the anthropogenic compound and natural one externally and/or internally. On the other hand, suspended particles matter (SPM) concentrations at ground level are compiled for these 10 years in this city. Strictly speaking, it is difficult to relate SPM data directly to the aerosol properties, however it is possible to say that SPM data represents the mass concentration of atmospheric particles at ground level. In other word, air pollutants could have some relations to the emission and transportation of aerosols. After several aerosol parameters are derived from the measurements and compared with the SPM data, the HYSPLIT4 backward trajectory analysis is adopted to search the origin of atmospheric particles. It is found that aerosol index shows a proportional correlation with SPM concentration, and that our aerosols are contaminated not only by surroundings but also the large scale phenomena, e.g. yellow sand event from China

  1. Sunphotometer network for monitoring aerosol properties in the Brazilian Amazon

    NASA Technical Reports Server (NTRS)

    Holben, Brent N.; Eck, T. F.; Setzer, A.; Pereira, Alfredo; Vermote, E.; Reagan, J. A.; Kaufman, Y. A.; Tanre, D.; Slutsker, I.

    1993-01-01

    Satellite platforms have provided a methodology for regional and global remote sensing of aerosols. New systems will significantly improve that capability during the EOS era; however, the voluminous 20 year record of satellite data has produced only regional snapshots of aerosol loading and have not yielded a data base of the optical properties of those aerosols which are fundamental to our understanding of their influence on climate change. The prospect of fully understanding the properties of the aerosols with respect to climate change is small without validation and augmentation by ancillary ground based observations. Sun photometry was demonstrated to be an effective tool for ground based measurements of aerosol optical properties from fire emissions. Newer technology has expanded routine sun photometer measurements to spectral observations of solar aureole and almucantar allowing retrievals of size distribution, scattering phase function, and refractive index. A series of such observations were made in Brazil's Amazon basin from a network of six simultaneously recording instruments deployed in Sep. 1992. The instruments were located in areas removed from local aerosol sources such that sites are representative of regional aerosol conditions. The overall network was designed to cover the counter clockwise tropospheric circulation of the Amazon Basin. Spectral measurements of sun, aureole and sky data for retrieval of aerosol optical thickness, particle size distribution, and scattering phase function as well as measurements of precipitable water were made during noncloudy conditions.

  2. Models to support active sensing of biological aerosol clouds

    NASA Astrophysics Data System (ADS)

    Brown, Andrea M.; Kalter, Jeffrey M.; Corson, Elizabeth C.; Chaudhry, Zahra; Boggs, Nathan T.; Brown, David M.; Thomas, Michael E.; Carter, Christopher C.

    2013-05-01

    Elastic backscatter LIght Detection And Ranging (LIDAR) is a promising approach for stand-off detection of biological aerosol clouds. Comprehensive models that explain the scattering behavior from the aerosol cloud are needed to understand and predict the scattering signatures of biological aerosols under varying atmospheric conditions and against different aerosol backgrounds. Elastic signatures are dependent on many parameters of the aerosol cloud, with two major components being the size distribution and refractive index of the aerosols. The Johns Hopkins University Applied Physics Laboratory (JHU/APL) has been in a unique position to measure the size distributions of released biological simulant clouds using a wide assortment of aerosol characterization systems that are available on the commercial market. In conjunction with the size distribution measurements, JHU/APL has also been making a dedicated effort to properly measure the refractive indices of the released materials using a thin-film absorption technique and laboratory characterization of the released materials. Intimate knowledge of the size distributions and refractive indices of the biological aerosols provides JHU/APL with powerful tools to build elastic scattering models, with the purpose of understanding, and ultimately, predicting the active signatures of biological clouds.

  3. Direct Aerosol Forcing Uncertainty

    DOE Data Explorer

    Mccomiskey, Allison

    2008-01-15

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  4. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  5. Portable Aerosol Contaminant Extractor

    DOEpatents

    Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

    2005-11-15

    A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

  6. Ganges valley aerosol experiment.

    SciTech Connect

    Kotamarthi, V.R.; Satheesh, S.K.

    2011-08-01

    In June 2011, the Ganges Valley Aerosol Experiment (GVAX) began in the Ganges Valley region of India. The objective of this field campaign is to obtain measurements of clouds, precipitation, and complex aerosols to study their impact on cloud formation and monsoon activity in the region.

  7. Aerosol climate time series from ESA Aerosol_cci (Invited)

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.

    2013-12-01

    Within the ESA Climate Change Initiative (CCI) the Aerosol_cci project (mid 2010 - mid 2013, phase 2 proposed 2014-2016) has conducted intensive work to improve algorithms for the retrieval of aerosol information from European sensors AATSR (3 algorithms), PARASOL, MERIS (3 algorithms), synergetic AATSR/SCIAMACHY, OMI and GOMOS. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Angstrom coefficient were retrieved from the other sensors. Global datasets for 2008 were produced and validated versus independent ground-based data and other satellite data sets (MODIS, MISR). An additional 17-year dataset is currently generated using ATSR-2/AATSR data. During the three years of the project, intensive collaborative efforts were made to improve the retrieval algorithms focusing on the most critical modules. The team agreed on the use of a common definition for the aerosol optical properties. Cloud masking was evaluated, but a rigorous analysis with a pre-scribed cloud mask did not lead to improvement for all algorithms. Better results were obtained using a post-processing step in which sudden transitions, indicative of possible occurrence of cloud contamination, were removed. Surface parameterization, which is most critical for the nadir only algorithms (MERIS and synergetic AATSR / SCIAMACHY) was studied to a limited extent. The retrieval results for AOD, Ångström exponent (AE) and uncertainties were evaluated by comparison with data from AERONET (and a limited amount of MAN) sun photometer and with satellite data available from MODIS and MISR. Both level2 and level3 (gridded daily) datasets were validated. Several validation metrics were used (standard statistical quantities such as bias, rmse, Pearson correlation, linear regression, as well as scoring approaches to quantitatively evaluate the spatial and temporal correlations against AERONET), and in some cases

  8. Improving Aerosol and Visibility Forecasting Capabilities Using Current and Future Generations of Satellite Observations

    DTIC Science & Technology

    2012-09-30

    framework for considering current and future satellite aerosol products. 2 . Develop forward models to enable a radiance assimilation capability by: 1...improving forecast performance over cloudy regions using the Ozone Monitoring Instrument (OMI) Aerosol Index; and 2 ) preparing for the post-MODIS... 2 . REPORT TYPE N/A 3. DATES COVERED - 4. TITLE AND SUBTITLE Improving Aerosol and Visibility Forecasting Capabilities Using Current and

  9. 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.

  10. Preliminary Results from an Assimilation of TOMS Aerosol Observations Into the GOCART Model

    NASA Technical Reports Server (NTRS)

    daSilva, Arlindo; Weaver, Clark J.; Ginoux, Paul; Torres, Omar; Einaudi, Franco (Technical Monitor)

    2000-01-01

    At NASA Goddard we are developing a global aerosol data assimilation system that combines advances in remote sensing and modeling of atmospheric aerosols. The goal is to provide high resolution, 3-D aerosol distributions to the research community. Our first step is to develop a simple assimilation system for Saharan mineral aerosol. The Goddard Chemistry and Aerosol Radiation model (GOCART) provides accurate 3-D mineral aerosol size distributions that compare well with TOMS satellite observations. Surface, mobilization, wet and dry deposition, convective and long-range transport are all driven by assimilated fields from the Goddard Earth Observing System Data Assimilation System, GEOS-DAS. Our version of GOCART transports sizes from.08-10 microns and only simulates Saharan dust. TOMS radiance observations in the ultra violet provide information on the mineral and carbonaceous aerosol fields. We use two main observables in this study: the TOMS aerosol index (AI) which is directly related to the ratio of the 340 and 380 radiances and the 380 radiance. These are sensitive to the aerosol optical thickness, the single scattering albedo and the height of the aerosol layer. The Goddard Aerosol Assimilation System (GAAS) uses the Data Assimilation Office's Physical-space Statistical Analysis System (PSAS) to combine TOMS observations and GOCART model first guess fields. At this initial phase we only assimilate observations into the the GOCART model over regions of Africa and the Atlantic where mineral aerosols dominant and carbonaceous aerosols are minimal, Our preliminary results during summer show that the assimilation with TOMS data modifies both the aerosol mass loading and the single scattering albedo. Assimilated aerosol fields will be compared with assimilated aerosol fields from GOCART and AERONET observations over Cape Verde.

  11. Aqueous aerosol SOA formation: impact on aerosol physical properties.

    PubMed

    Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

    2013-01-01

    Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  14. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  15. Dark Targets, Aerosols, Clouds and Toys

    NASA Astrophysics Data System (ADS)

    Remer, L. A.

    2015-12-01

    Today if you use the Thomson-Reuters Science Citations Index to search for "aerosol*", across all scientific disciplines and years, with no constraints, and you sort by number of citations, you will find a 2005 paper published in the Journal of the Atmospheric Sciences in the top 20. This is the "The MODIS Aerosol Algorithm, Products and Validation". Although I am the first author, there are in total 12 co-authors who each made a significant intellectual contribution to the paper or to the algorithm, products and validation described. This paper, that algorithm, those people lie at the heart of a lineage of scientists whose collaborations and linked individual pursuits have made a significant contribution to our understanding of radiative transfer and climate, of aerosol properties and the global aerosol system, of cloud physics and aerosol-cloud interaction, and how to measure these parameters and maximize the science that can be obtained from those measurements. The 'lineage' had its origins across the globe, from Soviet Russia to France, from the U.S. to Israel, from the Himalayas, the Sahel, the metropolises of Sao Paulo, Taipei, and the cities of east and south Asia. It came together in the 1990s and 2000s at the NASA Goddard Space Flight Center, using cultural diversity as a strength to form a common culture of scientific creativity that continues to this day. The original algorithm has spawned daughter algorithms that are being applied to new satellite and airborne sensors. The original MODIS products have been fundamental to analyses as diverse as air quality monitoring and aerosol-cloud forcing. AERONET, designed originally for the need of validation, is now its own thriving institution, and the lineage continues to push forward to provide new technology for the coming generations.

  16. Spatial heterogeneity of aerosol optical and radiative properties obtained from multiple satellite retrievals over the Sub-Himalayan region of North-East India

    NASA Astrophysics Data System (ADS)

    Pathak, Binita; Bhuyan, Pradip; Biswas, Jhuma; Dahutia, Papori

    North East India, nestled between the southeastern Tibetan Plateau on the north, the Indo Myanmar range of hills to the east, plains of Bangladesh to the south and the Indo-Gangetic plains (IGP) to the west has a unique topography and population inhabitation pattern. In recent decades, along with other parts of south Asia NE India has undergone rapid industrial and economic development. Lifestyle changes have increasingly added to the anthropogenic burden on the atmosphere in the plains while biomass burning due to shifting cultivation in the hills is a major source of particulate and gaseous pollution. Studies have suggested that during the Asian summer monsoon, boundary layer pollution from India, Southeast Asia and south China are lifted to the upper tropospheric region by convection followed by westward transport over the Middle East and the Mediterranean. The spatio-temporal variation of aerosol optical (viz. AOD, AAI, AAOD, AE, FMF, columnar mass concentration (CMC)) and radiative properties are studied using data from multiple satellite sensors: MODIS, OMI, TOMS, CERES at various locations within the NE India (22-30°N, 86-98°E) for the period 2000-2012. Significant spatio-temporal variation of aerosol optical and radiative properties is observed within the region. For example, Guwahati, the metropolitan city, shows maximum value of AOD, followed by Dhubri the location situated at the western corridor of north-east India. Minimum AOD is observed at the high altitude locations Thimphu and Tawang. Temporally AOD is overriding in March, April, May (MAM) at almost all the observation locations. The minimum AOD over the region in October-November (ON) is associated with the topography and local meteorology. AAI >0.5 at all the locations indicates presence of significant amount of absorbing aerosols. The peak AAI and AAOD in MAM at all the location is associated with the peak biomass burning activity and long range transportation from other locations of India and

  17. The organic aerosols of Titan

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Suits, F.; Callcott, T. A.; Williams, M. W.; Shrader, S.; Ogino, H.; Willingham, T. O.

    1984-01-01

    The optical properties and chemical composition of thiolin, an organic solid synthesized by high-energy-electron irradiation in a plasma discharge (Sagan et al., 1984) to simulate the high-altitude aerosols of Titan, are investigated experimentally using monochromators, ellipsometers, and spectrometers (on thin films deposited by continuous dc discharge) and sequential and nonsequential pyrolytic gas chromatography/mass spectrometry (of the volatile component), respectively. The results are presented in tables and graphs and characterized. The real and imaginary elements of the complex refractive index in the visible are estimated as 1.65 and 0.004-0.08, respectively, in agreement with observations of Titan, and the IR absorption features include the nitrile band at 4.6 microns. The molecules identified in the volatile part of thiolin include complex species considered important in theoretical models of the origin of life on earth.

  18. Retrieval of Aerosol Optical Depth Above Clouds from OMI Observations: Sensitivity Analysis, Case Studies

    NASA Technical Reports Server (NTRS)

    Torres, O.; Jethva, H.; Bhartia, P. K.

    2012-01-01

    A large fraction of the atmospheric aerosol load reaching the free troposphere is frequently located above low clouds. Most commonly observed aerosols above clouds are carbonaceous particles generally associated with biomass burning and boreal forest fires, and mineral aerosols originated in arid and semi-arid regions and transported across large distances, often above clouds. Because these aerosols absorb solar radiation, their role in the radiative transfer balance of the earth atmosphere system is especially important. The generally negative (cooling) top of the atmosphere direct effect of absorbing aerosols, may turn into warming when the light-absorbing particles are located above clouds. The actual effect depends on the aerosol load and the single scattering albedo, and on the geometric cloud fraction. In spite of its potential significance, the role of aerosols above clouds is not adequately accounted for in the assessment of aerosol radiative forcing effects due to the lack of measurements. In this paper we discuss the basis of a simple technique that uses near-UV observations to simultaneously derive the optical depth of both the aerosol layer and the underlying cloud for overcast conditions. The two-parameter retrieval method described here makes use of the UV aerosol index and reflectance measurements at 388 nm. A detailed sensitivity analysis indicates that the measured radiances depend mainly on the aerosol absorption exponent and aerosol-cloud separation. The technique was applied to above-cloud aerosol events over the Southern Atlantic Ocean yielding realistic results as indicated by indirect evaluation methods. An error analysis indicates that for typical overcast cloudy conditions and aerosol loads, the aerosol optical depth can be retrieved with an accuracy of approximately 54% whereas the cloud optical depth can be derived within 17% of the true value.

  19. Improved global aerosol datasets for 2008 from Aerosol_cci

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, Thomas; de Leeuw, Gerrit

    2013-04-01

    Within the ESA Climate Change Initiative (CCI) the Aerosol_cci project has meanwhile produced and validated global datasets from AATSR, PARASOL, MERIS, OMI and GOMOS for the complete year 2008. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Angstrom coefficient were retrieved from the three nadir sensors. For AATSR three algorithms were applied. AOD validation was conducted against AERONET sun photometer observations also in comparison to MODIS and MISR datasets. Validation included level2 (pixel level) and level3 (gridded daily) datasets. Several validation metrices were used and in some cases developed further in order to comprehensively evaluate the capabilities and limitations of the datasets. The metrices include standard statistical quantities (bias, rmse, Pearson correlation, linear regression) as well as scoring approaches to quantitatively assess the spatial and temporal correlations against AERONET. Over open ocean also MAN data were used to better constrain the aerosol background, but in 2008 had limited coverage. The validation showed that the PARASOL (ocean only) and AATSR (land and ocean) datasets have improved significantly and now reach the quality level and sometimes even go beyond the level of MODIS and MISR. However, the coverage of these European datasets is weaker than the one of the NASA datasets due to smaller instrument swath width. The MERIS dataset provides better coverage but has lower quality then the other datasets. A detailed regional and seasonal analysis revealed the strengths and weaknesses of each algorithm. Also, Angstrom coefficient was validated and showed encouraging results (more detailed aerosol type information provided in particular from PARASOL was not yet evaluated further). Additionally, pixel uncertainties contained in each dataset were statistically assessed which showed some remaining issues but also the added value

  20. Volcanic Aerosol Radiative Properties

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew

    2015-01-01

    Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

  1. Palaeoclimate: Aerosols and rainfall

    NASA Astrophysics Data System (ADS)

    Partin, Jud

    2015-03-01

    Instrumental records have hinted that aerosol emissions may be shifting rainfall over Central America southwards. A 450-year-long precipitation reconstruction indicates that this shift began shortly after the Industrial Revolution.

  2. Liposomal aerosols in the management of pulmonary infections.

    PubMed

    Gilbert, B E

    1996-01-01

    The combination of liposomes and aerosols has been utilized to directly target the lungs with chemotherapeutic agents that might not have been used because of low solubility or toxicity. There are a variety of antibacterials, antifungals, and antivirals that have good in vitro activity, but are not effective because of their systemic toxicity and/or poor penetration into the lungs. Incorporation of many lipophilic drugs into liposomes decreases their toxicity without affecting effectiveness, thus increasing the therapeutic index. We have focused on aerosol delivery of amphotericin B (ampB) for the treatment of pulmonary and systemic fungal diseases. We have tested a variety of ampB-lipid formulations for the optimal treatment regimen for Cryptococcus and Candida infections in mouse models. The AeroTech II nebulizer (MMADs of 1.8-2.2 microns) produced aerosols with the highest concentrations in the breathable range. Pharmacokinetic studies revealed that pulmonary drug was present for hours to weeks. AmBisome retained its anticryptococcal activity even when animals were challenged 14 days after aerosol treatment. Aerosols may also be effective in systemic diseases. In our Candida-mouse model, systemic candidiasis and mortality were reduced by aerosolized ampB-liposome treatment. The ability to utilize lipophilic drugs, to deliver high concentrations of drug directly to the site of infection, and to reduce toxicity makes aerosol liposomes an attractive, alternative route of administration.

  3. Satellite methods underestimate indirect climate forcing by aerosols

    PubMed Central

    Penner, Joyce E.; Xu, Li; Wang, Minghuai

    2011-01-01

    Satellite-based estimates of the aerosol indirect effect (AIE) are consistently smaller than the estimates from global aerosol models, and, partly as a result of these differences, the assessment of this climate forcing includes large uncertainties. Satellite estimates typically use the present-day (PD) relationship between observed cloud drop number concentrations (Nc) and aerosol optical depths (AODs) to determine the preindustrial (PI) values of Nc. These values are then used to determine the PD and PI cloud albedos and, thus, the effect of anthropogenic aerosols on top of the atmosphere radiative fluxes. Here, we use a model with realistic aerosol and cloud processes to show that empirical relationships for ln(Nc) versus ln(AOD) derived from PD results do not represent the atmospheric perturbation caused by the addition of anthropogenic aerosols to the preindustrial atmosphere. As a result, the model estimates based on satellite methods of the AIE are between a factor of 3 to more than a factor of 6 smaller than model estimates based on actual PD and PI values for Nc. Using ln(Nc) versus ln(AI) (Aerosol Index, or the optical depth times angstrom exponent) to estimate preindustrial values for Nc provides estimates for Nc and forcing that are closer to the values predicted by the model. Nevertheless, the AIE using ln(Nc) versus ln(AI) may be substantially incorrect on a regional basis and may underestimate or overestimate the global average forcing by 25 to 35%. PMID:21808047

  4. Emergency Protection from Aerosols

    SciTech Connect

    Cristy, G.A.

    2001-11-13

    Expedient methods were developed that could be used by an average person, using only materials readily available, to protect himself and his family from injury by toxic (e.g., radioactive) aerosols. The most effective means of protection was the use of a household vacuum cleaner to maintain a small positive pressure on a closed house during passage of the aerosol cloud. Protection factors of 800 and above were achieved.

  5. Monodisperse aerosol generator

    DOEpatents

    Ortiz, Lawrence W.; Soderholm, Sidney C.

    1990-01-01

    An aerosol generator is described which is capable of producing a monodisperse aerosol within narrow limits utilizing an aqueous solution capable of providing a high population of seed nuclei and an organic solution having a low vapor pressure. The two solutions are cold nebulized, mixed, vaporized, and cooled. During cooling, particles of the organic vapor condense onto the excess seed nuclei, and grow to a uniform particle size.

  6. Enhanced Deep Blue Aerosol Retrieval Algorithm: The Second Generation

    NASA Technical Reports Server (NTRS)

    Hsu, N. C.; Jeong, M.-J.; Bettenhausen, C.; Sayer, A. M.; Hansell, R.; Seftor, C. S.; Huang, J.; Tsay, S.-C.

    2013-01-01

    The aerosol products retrieved using the MODIS collection 5.1 Deep Blue algorithm have provided useful information about aerosol properties over bright-reflecting land surfaces, such as desert, semi-arid, and urban regions. However, many components of the C5.1 retrieval algorithm needed to be improved; for example, the use of a static surface database to estimate surface reflectances. This is particularly important over regions of mixed vegetated and non- vegetated surfaces, which may undergo strong seasonal changes in land cover. In order to address this issue, we develop a hybrid approach, which takes advantage of the combination of pre-calculated surface reflectance database and normalized difference vegetation index in determining the surface reflectance for aerosol retrievals. As a result, the spatial coverage of aerosol data generated by the enhanced Deep Blue algorithm has been extended from the arid and semi-arid regions to the entire land areas.

  7. In-depth discrimination of aerosol types using multiple clustering techniques over four locations in Indo-Gangetic plains

    NASA Astrophysics Data System (ADS)

    Bibi, Humera; Alam, Khan; Bibi, Samina

    2016-11-01

    Discrimination of aerosol types is essential over the Indo-Gangetic plain (IGP) because several aerosol types originate from different sources having different atmospheric impacts. In this paper, we analyzed a seasonal discrimination of aerosol types by multiple clustering techniques using AERosol RObotic NETwork (AERONET) datasets for the period 2007-2013 over Karachi, Lahore, Jaipur and Kanpur. We discriminated the aerosols into three major types; dust, biomass burning and urban/industrial. The discrimination was carried out by analyzing different aerosol optical properties such as Aerosol Optical Depth (AOD), Angstrom Exponent (AE), Extinction Angstrom Exponent (EAE), Abortion Angstrom Exponent (AAE), Single Scattering Albedo (SSA) and Real Refractive Index (RRI) and their interrelationship to investigate the dominant aerosol types and to examine the variation in their seasonal distribution. The results revealed that during summer and pre-monsoon, dust aerosols were dominant while during winter and post-monsoon prevailing aerosols were biomass burning and urban industrial, and the mixed type of aerosols were present in all seasons. These types of aerosol discriminated from AERONET were in good agreement with CALIPSO (the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) measurement.

  8. RACORO aerosol data processing

    SciTech Connect

    Elisabeth Andrews

    2011-10-31

    The RACORO aerosol data (cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter aerosol data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured aerosol size distributions. Below we first briefly describe the measurements and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several aerosol data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-aerosol interactions and improved cloud simulations in climate models.

  9. INDEXING MECHANISM

    DOEpatents

    Kock, L.J.

    1959-09-22

    A device is presented for loading and unloading fuel elements containing material fissionable by neutrons of thermal energy. The device comprises a combination of mechanical features Including a base, a lever pivotally attached to the base, an Indexing plate on the base parallel to the plane of lever rotation and having a plurality of apertures, the apertures being disposed In rows, each aperture having a keyway, an Index pin movably disposed to the plane of lever rotation and having a plurality of apertures, the apertures being disposed in rows, each aperture having a keyway, an index pin movably disposed on the lever normal to the plane rotation, a key on the pin, a sleeve on the lever spaced from and parallel to the index pin, a pair of pulleys and a cable disposed between them, an open collar rotatably attached to the sleeve and linked to one of the pulleys, a pin extending from the collar, and a bearing movably mounted in the sleeve and having at least two longitudinal grooves in the outside surface.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  11. Chemical, physical, and optical evolution of biomass burning aerosols: a case study

    NASA Astrophysics Data System (ADS)

    Adler, G.; Flores, J. M.; Abo Riziq, A.; Borrmann, S.; Rudich, Y.

    2011-02-01

    In-situ chemical composition measurements of ambient aerosols have been used for characterizing the evolution of submicron aerosols from a large anthropogenic biomass burning (BB) event in Israel. A high resolution Time of Flight Aerosol Mass Spectrometer (HR-RES-TOF-AMS) was used to follow the chemical evolution of BB aerosols during a night-long, extensive nationwide wood burning event and during the following day. While these types of extensive BB events are not common in this region, burning of agricultural waste is a common practice. The aging process of the BB aerosols was followed through their chemical, physical and optical properties. Mass spectrometric analysis of the aerosol organic component showed that aerosol aging is characterized by shifting from less oxidized fresh BB aerosols to more oxidized aerosols. Evidence for aerosol aging during the day following the BB event was indicated by an increase in the organic mass, its oxidation state, the total aerosol concentration, and a shift in the modal particle diameter. The effective broadband refractive index (EBRI) was derived using a white light optical particle counter (WELAS). The average EBRI for a mixed population of aerosols dominated by open fires was m = 1.53(±0.03) + 0.07i(±0.03), during the smoldering phase of the fires we found the EBRI to be m = 1.54(±0.01) + 0.04i(±0.01) compared to m = 1.49(±0.01) + 0.02i(±0.01) of the aged aerosols during the following day. This change indicates a decrease in the overall aerosol absorption and scattering. Elevated levels of particulate Polycyclic Aromatic Hydrocarbons (PAHs) were detected during the entire event, which suggest possible implications for human health during such extensive event.

  12. Volcanic Aerosols from Satellites: Current and Emerging Capabilities

    NASA Astrophysics Data System (ADS)

    Bhartia, P. K.; McCormick, M. P.; Loughman, R. P.

    2015-12-01

    There are 5 instruments currently operating in space with capability to measure stratospheric aerosols. Two of these are lidar backscatter instruments (CALIOP & ISS/CATS) that provide high vertical resolution, day/night coverage, and polarization information to separate ice clouds from sulfate aerosols. Two are limb scattering instruments (OSIRIS & OMPS-LP) with high sensitivity to aerosols and provide extensive spatial coverage of the sunlit globe. And a Canadian solar occultation instrument (ACE-MAESTRO) measures aerosol extinction twice per orbit. Next year we are expecting the launch of the SAGE III instrument on ISS with capability to measure aerosol extinction and Angstrom Exponent (AE) at multiple wavelengths by solar and lunar occultation techniques. It also has limb scattering capability to provide spatial coverage between solar occultations. The 51.6˚ inclination of the ISS orbit will allow SAGE III to measure aerosol scattering across the gobe for a wide range of scattering angles. Therefore, ISS SAGE III has the capability to provide vertically resolved information about a wide variety of aerosol properties, potentially including aerosol extinction, size distribution, refractive index, and particle shape parameters, similar to the one provided by the ground-based almucantar technique. In our talk we will focus primarily on the synergy between the OMPS LP instrument that has been flying on the Suomi NPP satellite since October 2011 and ISS SAGE III. We will show how these measurements can be combined together to capture spatial and temporal evolution of aerosols and ozone in large volcanic plumes to validate models and to support field campaigns.

  13. Retrieval of aerosol climatology from Sun-Photometer measurements at Andenes, Norway.

    NASA Astrophysics Data System (ADS)

    Chen, Y. C.; Hamre, B.; Stamnes, S.; Frette, Ø.; Stamnes, K.; Stamnes, J. J.

    2012-04-01

    The chemical composition and loading of aerosols along the Norwegian coast are expected to be highly varying, making accurate remote sensing of coastal waters difficult. As a first step to remedy this shortcoming, we used a coupled atmosphere-ocean discrete ordinate radiative transfer model (C-DISORT) to investigate the sensitivity of the spectral and angular radiance distributions at the surface to variations in the concentration, size distribution, spectral refractive index of aerosols as well as to variations in the surface albedo. Secondly, we used Aerosol Robotic Network (AERONET) data from Andenes, Norway (69N, 16E) in combination with C-DISORT computations to retrieve a set of aerosol physical parameters which, when varied, caused significant variations in the surface radiances. The goal is to apply this retrieval method to long-term AERONET time series at Andenes in order to classify aerosol physical properties and build up an aerosol climatology database.

  14. Disposition of aerosolized liposomal amphotericin B.

    PubMed

    Lambros, M P; Bourne, D W; Abbas, S A; Johnson, D L

    1997-09-01

    Amphotericin B (AmB) is an important drug for the treatment of fungal infection, but toxicity limits the lung tissue doses which may be achieved through intravenous administration. Although incorporation of AmB in liposomes reduces these effects and increases the therapeutic index for intravenous administration, targeted delivery to lung tissues via inhaled liposomal AmB aerosol may be a more effective approach. Aerosolization of liposomal amphotericin B targets the lungs, the organs first infested by many fungi. Development of optimal aerosolized liposomal AmB therapies requires a better understanding of the effect that liposome surface charge has on lung clearance kinetics. In this work we evaluated the clearance kinetics and organ distribution of inhaled liposomal AmB in male Balb/C mice. Mice were exposed via nose only to AmB-containing liposomal aerosols having positive, negative, or neutral surface charge characteristics. The formulations were aerosolized using a Collison nebulizer. Groups of animals were euthanized at predetermined times and the lungs and other organs were analyzed for AmB. AmB was not detected in serum and other organs such as kidneys, liver, and brain. The disposition of neutral and positive liposomal amphotericin B in lungs followed biexponential kinetics. The alpha and beta phase half-lives for positive liposomes were 1.3 and 15.1 days, respectively, and 2.3 and 22 days for neutral liposomes. AmB delivered via negative liposomes exhibited monoexponential clearance with a half-life of 4.5 days. These results suggest that toxic side effects in nontarget tissues are minimal and may indicate a potential for long term protection against fungal infections.

  15. Estimate of the aerosol properties over the ocean with POLDER

    NASA Astrophysics Data System (ADS)

    Deuzé, J. L.; Goloub, P.; Herman, M.; Marchand, A.; Perry, G.; Susana, S.; Tanré, D.

    2000-06-01

    The wide field of view imaging spectroradiometer Polarization and Directionality of the Earth's Reflectance (POLDER) developed by Centre National d'Etudes Spatiales and operated aboard the Japanese heliosynchronous platform Advanced Earth Observation Satellite (ADEOS) from October 30, 1996, to June 30, 1997, provided the first global systematic measurements of the spectral, directional, and polarized characteristics of the solar radiation reflected by the Earth/atmosphere system. These original observational capabilities offer an opportunity to enhance the characterization of several components of the global environment, especially the oceanic and terrestrial vegetal primary production, the aerosol physical and optical properties, and the tridimensional structure and microphysics of clouds. Here we examine the remote sensing of aerosols over the oceans. In a first step the aerosol optical thickness and Ångström exponent are derived from the radiance measurements. In a second step the polarization measurements are used for the retrieval of the aerosol refractive index. The inversion algorithm assumes spherical, nonabsorbing particles with monomodal lognormal size distribution. The adequacy of this modeling is discussed for a representative set of aerosol observations. Successful retrieval is generally achieved in the presence of small aerosols with Ångström exponent larger than ˜1.0. For such particles, polarization may provide information on the particle refractive index. As the Ångstrom exponent of the particle decreases, the data fitting residual errors increase, especially in polarized light, which prevents the retrieval of the aerosol refractive index. The trends of the discrepancies point out two shortcomings of the aerosol modeling. The theoretical results systematically underestimate the contribution of small polarizing particles in the polarization measurements for side-scattering angles ranging from 80° to 120°. This indicates very probably that

  16. Validation of Retrieved Aerosol Optical Properties over Northeast Asia for Five Years from GOSAT TANSO-Cloud and Aerosol Imager

    NASA Astrophysics Data System (ADS)

    Kim, J.; Lee, S.; KIM, M.; Choi, M.; Go, S.; Lim, H.; Goo, T. Y.; Nakajima, T.; Kuze, A.; Shiomi, K.; Yokota, T.

    2015-12-01

    An aerosol retrieval algorithm was developed from Thermal And Near infrared Sensor for carbon Observation-Cloud and Aerosol Imager (TANSO-CAI) onboard the Greenhouse Gases Observing Satellite (GOSAT). The algorithm retrieves aerosol optical depth (AOD), size distribution of aerosol, and aerosol type in 0.1 degree grid resolution by look-up tables, which is used in retrieving optical properties of aerosol using inversion products from Aerosol Robotic NETwork (AERONET) sun-photometer observation. To improve the accuracy of aerosol algorithm, first, this algorithm considered the annually estimated radiometric degradation factor of TANSO-CAI suggested by Kuze et al. (2014). Second, surface reflectance was determined by two methods: one using the clear sky composite method from CAI measurements and the other the database from MODerate resolution Imaging Sensor (MODIS) surface reflectance data. At a given pixel, the surface reflectance is selected by using normalized difference vegetation index (NDVI) depending on season (Hsu et al., 2013). In this study, the retrieved AODs were compared with those of AERONET and MODIS dataset for different season over five years. Comparisons of AODs between AERONET and CAI show reasonable agreement with correlation coefficients of 0.65 ~ 0.97 and regression slopes between 0.7 and 1.2 for the whole period, depending on season and sites. Moreover, those between MODIS and CAI for the same period show agreements with correlation coefficients of 0.7 ~ 0.9 and regression slopes between 0.7 and 1.0, depending on season and regions. The results show reasonably good correlation, however, the largest error source in aerosol retrieval has been surface reflectance of TANSO-CAI due to its 3-days revisit orbit characteristics.

  17. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  18. Palaeoclimate: Aerosols shift lake ecosystem

    NASA Astrophysics Data System (ADS)

    Dowsett, Harry J.

    2017-02-01

    Anthropogenic aerosols over the Chinese Loess Plateau have diminished monsoon precipitation and concomitant soil erosion that plagues the region. Now, a reconstruction documents the differences between historical warming events and the present, highlighting the paradoxical implications of decreasing atmospheric aerosols.

  19. Generation of aerosolized drugs.

    PubMed

    Wolff, R K; Niven, R W

    1994-01-01

    The expanding use of inhalation therapy has placed demands on current aerosol generation systems that are difficult to meet with current inhalers. The desire to deliver novel drug entities such as proteins and peptides, as well as complex formulations including liposomes and microspheres, requires delivery systems of improved efficiency that will target the lung in a reproducible manner. These efforts have also been spurred by the phase out of chlorofluorocarbons (CFCs) and this has included a directed search for alternative propellants. Consequently, a variety of new aerosol devices and methods of generating aerosols are being studied. This includes the use of freon replacement propellants, dry powder generation systems, aqueous unit spray systems and microprocessor controlled technologies. Each approach has advantages and disadvantages depending upon each principle of action and set of design variables. In addition, specific drugs may be better suited for one type of inhaler device vs. another. The extent to which aerosol generation systems achieve their goals is discussed together with a summary of selected papers presented at the recent International Congress of Aerosols in Medicine.

  20. Aerosol chemistry in GLOBE

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.; Rothermel, Jeffry; Jarzembski, Maurice A.

    1993-01-01

    This task addresses the measurement and understanding of the physical and chemical properties of aerosol in remote regions that are responsible for aerosol backscatter at infrared wavelengths. Because it is representative of other clean areas, the remote Pacific is of extreme interest. Emphasis is on the determination size dependent aerosol properties that are required for modeling backscatter at various wavelengths and upon those features that may be used to help understand the nature, origin, cycling and climatology of these aerosols in the remote troposphere. Empirical relationships will be established between lidar measurements and backscatter derived from the aerosol microphysics as required by the NASA Doppler Lidar Program. This will include the analysis of results from the NASA GLOBE Survey Mission Flight Program. Additional instrument development and deployment will be carried out in order to extend and refine this data base. Identified activities include participation in groundbased and airborne experiments. Progress to date includes participation in, analysis of, and publication of results from Mauna Loa Backscatter Intercomparison Experiment (MABIE) and Global Backscatter Experiment (GLOBE).

  1. Analysis of Measurement Requirements for the Aerosol Indirect Effect: A Synthesis of Observations and Modeling

    NASA Astrophysics Data System (ADS)

    Feingold, G.; Previdi, M.; Veron, D. E.

    2003-12-01

    The aerosol indirect effect has been measured for some time now by satellite remote sensors, and more recently by surface-based remote sensors. The indirect effect is often expressed in terms of a relative change in drop size for a relative change in aerosol optical depth or extinction. Here we present some recent results of surface based remote sensing of the indirect effect and assess whether aerosol optical depth or extinction is a suitable proxy for the aerosol affecting drop formation. To do so, we use multiple realizations of a cloud model to investigate the sensitivity of cloud drop effective radius re to aerosol parameters (size distribution and composition) and dynamical parameters (updraft and liquid water content). A breakdown of the individual aerosol terms contributing to drop size change shows that use of aerosol extinction as a proxy for size distribution and composition tends to underestimate the magnitude of the first indirect effect. The use of the aerosol index alleviates this problem somewhat. We show that re is most sensitive to cloud liquid water, a parameter often ignored in indirect effect analyses. The relative importance of the other parameters varies for different conditions but aerosol concentration Na is consistently important. Updraft plays an increasingly important role under high aerosol loadings. Requirements for measuring the indirect effect over polluted continents are shown to be more stringent than those over cleaner, remote oceans. This may influence interpretation of current satellite and surface remote measurements of the indirect effect.

  2. Internally Consistent MODIS Estimate of Aerosol Clear-Sky Radiative Effect Over the Global Oceans

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Kaufman, Yoram J.

    2004-01-01

    Modern satellite remote sensing, and in particular the MODerate resolution Imaging Spectroradiometer (MODIS), offers a measurement-based pathway to estimate global aerosol radiative effects and aerosol radiative forcing. Over the Oceans, MODIS retrieves the total aerosol optical thickness, but also reports which combination of the 9 different aerosol models was used to obtain the retrieval. Each of the 9 models is characterized by a size distribution and complex refractive index, which through Mie calculations correspond to a unique set of single scattering albedo, assymetry parameter and spectral extinction for each model. The combination of these sets of optical parameters weighted by the optical thickness attributed to each model in the retrieval produces the best fit to the observed radiances at the top of the atmosphere. Thus the MODIS Ocean aerosol retrieval provides us with (1) An observed distribution of global aerosol loading, and (2) An internally-consistent, observed, distribution of aerosol optical models that when used in combination will best represent the radiances at the top of the atmosphere. We use these two observed global distributions to initialize the column climate model by Chou and Suarez to calculate the aerosol radiative effect at top of the atmosphere and the radiative efficiency of the aerosols over the global oceans. We apply the analysis to 3 years of MODIS retrievals from the Terra satellite and produce global and regional, seasonally varying, estimates of aerosol radiative effect over the clear-sky oceans.

  3. Investigation of trace gas to aerosol relationships over biomass burning areas using daily satellite observations

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas; Penning de Vries, Marloes; Zörner, Jan; Beirle, Steffen

    2014-05-01

    The quantification and characterization of aerosols from space is a great challenge. Especially in the presence of clouds and over land surfaces, it is often difficult to distinguish the signals of aerosol scattering from scattering by cloud particles or surface reflection. Instead of deriving aerosol properties directly, satellite observations of tropospheric trace gases, emitted by the same emission sources as the aerosols, can be used to derive additional information on the aerosols. Such observations have two potential advantages: First, from the composition of trace gases, information on the aerosol type can be derived. Second, such observations are possible in the presence of clouds (although usually with reduced sensitivity if the trace gases are located below the cloud). In this feasibility study we investigate the relationship between satellite observations of trace gases (CO, NO2, HCHO, CHOCHO) and AOD (measured from satellite or ground). We also include in our comparison satellite observations of the so called UV aerosol index (UVAI), which is an indicator of the aerosol absorption. Like the trace gas observations, also the UVAI can be retrieved in the presence of clouds. We investigate aerosol-trace gas relationships over biomass burning regions. Depending on their optical properties and altitude distribution such aerosols can have a strong impact on the atmospheric energy budget through direct and indirect effects. We perform correlation analyses for selected AERONET stations and also for larger biomass burning areas by also taking into account satellite observations of fire counts.

  4. Characterization of absorbing aerosol types using ground and satellites based observations over an urban environment

    NASA Astrophysics Data System (ADS)

    Bibi, Samina; Alam, Khan; Chishtie, Farrukh; Bibi, Humera

    2017-02-01

    In this paper, for the first time, an effort has been made to seasonally characterize the absorbing aerosols into different types using ground and satellite based observations. For this purpose, optical properties of aerosol retrieved from AErosol RObotic NETwork (AERONET) and Ozone Monitoring Instrument (OMI) were utilized over Karachi for the period 2012 to 2014. Firstly, OMI AODabs was validated with AERONET AODabs and found to have a high degree of correlation. Then, based on this validation, characterization was conducted by analyzing aerosol Fine Mode Fraction (FMF), Angstrom Exponent (AE), Absorption Angstrom Exponent (AAE), Single Scattering Albedo (SSA) and Aerosol Index (AI) and their mutual correlation, to identify the absorbing aerosol types and also to examine the variability in seasonal distribution. The absorbing aerosols were characterized into Mostly Black Carbon (BC), Mostly Dust and Mixed BC & Dust. The results revealed that Mostly BC aerosols contributed dominantly during winter and postmonsoon whereas, Mostly Dust were dominant during summer and premonsoon. These types of absorbing aerosol were also confirmed with MODerate resolution Imaging Spectroradiometer (MODIS) and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) observations.

  5. Analysis of aerosol optical and microphysical properties observed during the DC3 field study

    NASA Astrophysics Data System (ADS)

    Chen, G.; Schuster, G. L.; Anderson, B. E.; Jimenez, J. L.; Campuzano Jost, P.; Dibb, J. E.; Scheuer, E. M.; Ziemba, L. D.; Beyersdorf, A. J.; Thornhill, K. L.; Moore, R.; Winstead, E.; Markovic, M. Z.

    2013-12-01

    The Deep Convective Clouds and Chemistry Experiment (DC3) consisted of 18 research flights from Salina, KS. During cloud inflow and outflow surveys, various aged aerosol layers and plumes, including biomass burning, were sampled by the NASA DC-8 aircraft which was equipped with a broad suite of instruments for aerosol optical, microphysical, and chemical properties. As a result, the DC3 dataset includes detailed aerosol number size distribution, bulk aerosol mass concentration, black carbon mass concentration, and mass size distribution for sulfate, nitrate, ammonium and organics, together with scattering and absorption coefficients. We use this comprehensive dataset to perform a detailed closure analysis to examine the consistency between the observed aerosol properties and the literature reported aerosol refractive index values. In this context, we report aerosol observations, and comparisons between the aerosol mass and number size distribution for various aerosol layers. Closure tests will also be presented in terms of the impact of the aerosol composition and size distribution on the scattering and absorption.

  6. Source apportionment of absorbing aerosols in the central Indo-Gangetic Plain

    NASA Astrophysics Data System (ADS)

    Vaishya, Aditya; Singh, Prayagraj; Rastogi, Shantanu; Babu, S. Suresh

    2016-05-01

    Atmospheric aerosols in the Indo-Gangetic Plain (IGP) depicts high spatial and temporal heterogeneity in their radiative properties. Despite the fact that significant advancement in terms of characterizing aerosols radiative and physiochemical properties in the IGP have been made, information regarding the organic content towards total absorbing aerosol budget is lacking. In the present study we have analyzed two years of aerosol spectral light absorption measurements from the central-IGP, Gorakhpur (26.75°N, 83.38°E, 85m amsl), in order to study their seasonal behavior and to quantify their magnitude in terms of absorbing aerosols loading and source speciation. Remote sensing data in the form of 'Cloud corrected Fire Count' from MODIS Terra and 'Absorption Aerosol Index' from OMI satellites platform have been used to identify absorbing aerosol source regions. Spectral absorption analysis reveals a four-fold enhancement in absorption in the winter (W) and the post-monsoon (PoM) seasons at UV wavelengths as compared to 880 nm on account of increased biomass aerosol contribution to total absorbing aerosol load. Despite having higher fire events and absorption aerosol index, both indicating high biomass burning activities, in the pre-monsoon (PM) season, aerosols from the biomass sources contribute ~ 27% during the W and the PoM seasons as against ~17% in the PM season to the total absorbing aerosol content. This is due to near stagnant wind conditions and shallow height of air masses travelling to the central IGP in the W and the PoM seasons.

  7. AERONET-based microphysical and optical properties of smoke-dominated aerosol near source regions and transported over oceans, and implications for satellite retrievals of aerosol optical depth

    NASA Astrophysics Data System (ADS)

    Sayer, A. M.; Hsu, N. C.; Eck, T. F.; Smirnov, A.; Holben, B. N.

    2013-09-01

    Smoke aerosols from biomass burning are an important component of the global aerosol cycle. Analysis of Aerosol Robotic Network (AERONET) retrievals of size distribution and refractive index reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke transported to coastal/island AERONET sites also mostly lie within the range of variability at near-source sites. Two broad ''families'' of aerosol properties are found, corresponding to sites dominated by boreal forest burning (larger, broader fine mode, with midvisible SSA ∼0.95), and those influenced by grass, shrub, or crop burning with additional forest contributions (smaller, narrower particles with SSA ∼0.88-0.9 in the midvisible). The strongest absorption is seen in southern African savannah at Mongu (Zambia), with average SSA ∼0.85 in the midvisible. These can serve as candidate sets of aerosol microphysical/optical properties for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean are often insufficiently absorbing to represent these biomass burning aerosols. A corollary of this is an underestimate of AOD in smoke outflow regions, which has important consequences for applications of these satellite datasets.

  8. Aeronet-based Microphysical and Optical Properties of Smoke-dominated Aerosol near Source Regions and Transported over Oceans, and Implications for Satellite Retrievals of Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

    Sayer, A. M.; Hsu, N. C.; Eck, T. F.; Smirnov, A.; Holben, B. N.

    2013-01-01

    Smoke aerosols from biomass burning are an important component of the global aerosol cycle. Analysis of Aerosol Robotic Network (AERONET) retrievals of size distribution and refractive index reveals variety between biomass burning aerosols in different global source regions, in terms of aerosol particle size and single scatter albedo (SSA). Case studies of smoke transported to coastal/island AERONET sites also mostly lie within the range of variability at near-source sites. Two broad families of aerosol properties are found, corresponding to sites dominated by boreal forest burning (larger, broader fine mode, with midvisible SSA 0.95), and those influenced by grass, shrub, or crop burning with additional forest contributions (smaller, narrower particles with SSA 0.88-0.9 in the midvisible). The strongest absorption is seen in southern African savanna at Mongu (Zambia), with average SSA 0.85 in the midvisible. These can serve as candidate sets of aerosol microphysicaloptical properties for use in satellite aerosol optical depth (AOD) retrieval algorithms. The models presently adopted by these algorithms over ocean are often insufficiently absorbing to represent these biomass burning aerosols. A corollary of this is an underestimate of AOD in smoke outflow regions, which has important consequences for applications of these satellite datasets.

  9. Chemical aerosol Raman detector

    NASA Astrophysics Data System (ADS)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Amin, M.; Perkins, B. G.; Clark, M. L.; Jeys, T. H.; Sickenberger, D. W.; D'Amico, F. M.; Emmons, E. D.; Christesen, S. D.; Kreis, R. J.; Kilper, G. K.

    2017-03-01

    A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

  10. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  11. Highly stable aerosol generator

    SciTech Connect

    DeFord, Henry S.; Clark, Mark L.

    1981-01-01

    An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly.

  12. Highly stable aerosol generator

    DOEpatents

    DeFord, H.S.; Clark, M.L.

    1981-11-03

    An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly. 2 figs.

  13. Evaluation of AERONET Aerosol Retrievals

    NASA Astrophysics Data System (ADS)

    Schuster, G. L.; Dubovik, O.; Rutledge, C. K.

    2001-12-01

    The aerosol robotic network (AERONET) program provides aerosol retrievals at ground-based sunphotometer sites throughout the world. The aerosol size distributions and refractive index retrievals at two locations have been converted to phase functions and single-scattering albedo using Mie theory. These optical properties are incorporated into a discrete-ordinates radiative transfer model and calculations are compared to independent measurements obtained at the surface. The independent measurements include principle plane radiances from sunphotometer data and narrowband irradiances from multi-filter rotating shadowband radiometer (MFRSR) and rotating shadowband spectroradiometer (RSS) data. The two locations represent radically different environments. The Atmospheric Radiation Measurement (ARM) program Central Facility (CF) represents a rural continental environment, while the CERES (Clouds and the Earth's Radiant Energy System) Ocean Validation Experiment (COVE) site represents a coastal marine environment. Both sites exhibit good agreement between the model calculations and the principle plane radiances for the year 2000 (generally better than 15 percent at optical depths greater than 0.1). A comparison with RSS measurements in July 2000 at the ARM Central Facility shows an irradiance error of 12 percent or better at tested wavelenghs longer than 500 nm. Comparisons with MFRSR data fared less well, however, indicating a discrepancy between the instruments. Inspection of 28 whole-sky imager (WSI) files coincidental with all AERONET quality-controlled retrievals during 7 days reveals that no clouds were obstructing the almucantar field of view and that indeed the whole sky was clear during this period, indicating a degree of robustness in the AERONET cloud screening. Additionally, the size distributions were evaluated at COVE with hourly-averaged wind speed and direction. Linear regression indicates that the coarse mode column-integrated surface area increases from

  14. Uncertainties of aerosol retrieval from neglecting non-sphericity of dust aerosols

    NASA Astrophysics Data System (ADS)

    Li, Chi; Xue, Yong; Yang, Leiku; Guang, Jie

    2013-04-01

    The Mie theory is conventionally applied to calculate aerosol optical properties in satellite remote sensing applications, while dust aerosols cannot be well modeled by the Mie calculation for their non-sphericity. It has been cited in Mishchenko et al. (1995; 1997) that neglecting non-sphericity can severely influence aerosol optical depth (AOD, ?) retrieval in case of dust aerosols because of large difference of phase functions under spherical and non-spherical assumptions, whereas this uncertainty has not been thoroughly studied. This paper aims at a better understanding of uncertainties on AOD retrieval caused by aerosol non-sphericity. A dust aerosol model with known refractive index and size distribution is generated from long-term AERONET observations since 1999 over China. Then aerosol optical properties, such as the extinction, phase function, single scattering albedo (SSA) are calculated respectively in the assumption of spherical and non-spherical aerosols. Mie calculation is carried out for spherical assumption, meanwhile for non-spherical aerosol modeling, we adopt the pre-calculated scattering kernels and software package presented by Dubovik et al. (2002; 2006), which describes dust as a shape mixture of randomly oriented polydisperse spheroids. Consequently we generate two lookup tables (LUTspheric and LUTspheroid) from simulated satellite received reflectance at top of atmosphere (TOA) under varieties of observing conditions and aerosol loadings using Second Simulation of a Satellite Signal in the Solar Spectrum - Vector (6SV) code. All the simulations are made at 550 nm, and for simplicity the Lambertian surface is assumed. Using the obtained LUTs we examine the differences of TOA reflectance (Δ?TOA = ?spheric - ?spheroid) under different surface reflectance and aerosol loadings. Afterwards AOD is retrieved using LUTspheric from the simulated TOA reflectance by LUTspheroid in order to detect the retrieval errors (Δ? = ?retreived -?input) induced

  15. Combined Use of Satellite and Surface Observations to Infer the Imaginary Part of Refractive Index of Saharan Dust

    NASA Technical Reports Server (NTRS)

    Sinyuk, Alexander; Torres, Omar; Dubovik, Oleg; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    We present a method for retrieval of the imaginary part of refractive index of desert dust aerosol in the near UV part of spectrum. The method uses Total Ozone Mapping Spectrometer (TOMS) measurements of the top of the atmosphere radiances at 331 and 360 run and aerosol optical depth provided by the Aerosol Robotic Network (AERONET). Obtained values of imaginary part of refractive index retrieved for Saharan dust aerosol at 360 nm are significantly lower than previously reported values. The average retrieved values vary between 0.0054 and 0.0066 for different geographical locations. Our findings are in good agreement with the results of several recent investigations.

  16. Aerosol contributions to speleothem geochemistry

    NASA Astrophysics Data System (ADS)

    Dredge, J. A.; Fairchild, I. J.; Harrison, R.; Woodhead, J. D.; Hellstrom, J.

    2011-12-01

    The term "aerosols" encompasses the suspension of both fine solid or liquid particles within a gaseous medium. Aerosols become suspended into the earth's atmosphere through a multitude of processes both natural and anthropogenic. Atmospheric aerosols enter cave networks as a result of cave ventilation processes and are either deposited, or cycled and removed from the system. Speleothem offer a multiproxy palaeoclimate resource; many of the available proxies have been extensively investigated and utilised for palaeoclimatic reconstructions in a range of studies. The potential contribution of aerosols to speleothem chemistry and their applicability for palaeoenvironmental reconstructions remains untested and the extent of their value as an addition to palaeoclimate sciences unknown. Aerosols through incorporation into speleothem may provide a novel palaeoenvironmental resource. The aerosol component of interest is that which is transported into the cave atmosphere and deposited and are available for incorporation into precipitated calcite. Aerosol deposition and therefore distribution in the cave has shown to be a complex function of ventilation and changing environmental factors. Through detailed monitoring aerosols have been detected, identified, characterised and quantified to determine their prominence in the cave system. Investigations are on a case study basis, searching for suitable aerosol proxies of environmentally significant emission processes. Case studies include: Palaeofires at Yarrangobilly Caves, Australia; anthropogenic emissions at St Michaels Cave, Gibraltar and Cheddar gorge, UK; and drip water aerosol production and geochemical addition in Obir cave, Austria. Monitoring has allowed for the temporal and spatial determination of aerosols in karst networks. Speleothem samples will be analysed in combination with in-situ monitoring to determine incorporation factors and record preservation. By understanding how aerosols are transmitted within the

  17. American Association for Aerosol Research (AAAR) `95

    SciTech Connect

    1995-12-31

    The Fourteenth annual meeting of the American Association for Aerosol Research was held October 9-13, 1995 at Westin William Penn Hotel in Pittsburgh, PA. This volume contains the abstracts of the papers and poster sessions presented at this meeting, grouped by the session in which they were presented as follows: Radiation Effects; Aerosol Deposition; Collision Simulations and Microphysical Behavior; Filtration Theory and Measurements; Materials Synthesis; Radioactive and Nuclear Aerosols; Aerosol Formation, Thermodynamic Properties, and Behavior; Particle Contamination Issues in the Computer Industry; Pharmaceutical Aerosol Technology; Modeling Global/Regional Aerosols; Visibility; Respiratory Deposition; Biomass and Biogenic Aerosols; Aerosol Dynamics; Atmospheric Aerosols.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  19. Multiwavelength multistatic optical scattering for aerosol characterization

    NASA Astrophysics Data System (ADS)

    Brown, Andrea M.

    The main focus of this research is the development of a technique to remotely characterize aerosol properties, such as particle size distribution, concentration, and refractive index as a function of wavelength, through the analysis of optical scattering measurements. The proposed technique is an extension of the multistatic polarization ratio technique that has been developed by prior students at the Penn State Lidar Lab to include multiple wavelengths. This approach uses the ratio of polarized components of the scattering phase functions at multiple wavelengths across the visible region of the electromagnetic spectrum to extract the microphysical and optical properties of aerosols. The scattering intensities at each wavelength are vertically separated across the face of the imager using a transmission diffraction grating, so that scattering intensities for multiple wavelengths at many angles are available for analysis in a single image. The ratio of the scattering phase function intensities collected using parallel and perpendicular polarized light are formed for each wavelength and analysis of the ratio is used to determine the microphysical properties of the aerosols. One contribution of the present work is the development of an inversion technique based on a genetic algorithm that retrieves lognormal size distributions from scattering measurements by minimizing the squared error between measured polarization ratios and polarization ratios calculated using the Mie solution to Maxwell's equations. The opportunities and limitations of using the polarization ratio are explored, and a genetic algorithm is developed to retrieve single mode and trimodal lognormal size distributions from multiwavelength, angular scattering data. The algorithm is designed to evaluate particles in the diameter size range of 2 nm to 60 im, and uses 1,000 linear spaced diameters within this range to compute the modeled polarization ratio. The algorithm returns geometric mean radii and

  20. 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.

  1. Production of satellite-derived aerosol climate data records: current status of the ESA Aerosol_cci project

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    and the Aerosol_cci team Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (Phase 1: 2010 -2014; Phase 2: 2014-2017) intensive work has been conducted to improve algorithms for the retrieval of aerosol information from European sensors ATSR (3 algorithms), PARASOL, MERIS (3 algorithms), synergetic AATSR/SCIAMACHY, OMI and GOMOS. Whereas OMI and GOMOS were used to derive absorbing aerosol index and stratospheric extinction profiles, respectively, Aerosol Optical Depth (AOD) and Ångström coefficient were retrieved from the other sensors. The cooperation between the project partners, including both the retrieval teams and independent validation teams, has resulted in a strong improvement of most algorithms. In particular the AATSR retrieved AOD is qualitatively similar to that from MODIS, usually taken as the standard, MISR and SeaWiFS. This conclusion has been reached form several different ways of validation of the L2 and L3 products, using AERONET sun photometer data as the common ground-truth for the application of both 'traditional' statistical techniques and a 'scoring' technique using spatial and temporal correlations. Quantitatively, the limited AATSR swath width of 500km results in a smaller amount of data. Nevertheless, the assimilation of AATSR-retrieved AOD, together with MODIS data, contributes to improving the in the ECMWF climate model results. In addition to the multi-spectral AOD, and thus the Ångström Exponent, also a per-pixel uncertainty is provided and validated. By the end of Aerosol_cci Phase 1 the ATSR algorithms have been applied to both ATSR-2 and AATSR resulting in an AOD time series of 17 years. In phase 2 this work is continued with a focus on the further improvement of the ATSR algorithms as well as those for the other instruments and algorithms, mentioned above, which in phase 1 were considered less mature. The first efforts are on the further characterization of the uncertainties and on better understanding of the

  2. Mixing state of aerosols over the Indo-Gangetic Plain: Radiative forcing and heating rate

    NASA Astrophysics Data System (ADS)

    Srivastava, R.; Ramachandran, S.

    2012-12-01

    Aerosols are a major atmospheric variable which perturb the Earth-atmosphere radiation balance by absorbing and scattering the solar and terrestrial radiation. Aerosols are produced by natural and anthropogenic processes. The presence of different types of aerosol over a location and aerosols transported from long-range can give rise to different mixing states because of aging and interaction among the different aerosol species. Knowledge of the mixing state of aerosols is important for an accurate assessment of aerosols in climate forcing, as assumptions regarding the mixing state of aerosol and its effect on optical properties can give rise to uncertainties in modeling their direct and indirect effects [1]. Seasonal variations in mixing states of aerosols over an urban (Kanpur) and a rural location (Gandhi College) in the Indo-Gangetic Plain (IGP) are determined using the measured and modeled aerosol optical properties, and the impact of aerosol mixing state on aerosol radiative forcing are investigated. IGP is one of the most populated and polluted river basins in the world, rich in fertile lands and agricultural production. Kanpur is an urban, industrial and densely populated city, and has several large/small scale industries and vehicles, while Gandhi College in IGP is a rural village, located southeast of Kanpur. Aerosol optical properties obtained from Aerosol Robotic Network sun/sky radiometers [2] over these two environmentally distinct locations in Indo-Gangetic Plain are used in the study, along with aerosol vertical profiles obtained from CALIPSO (Cloud- Aerosol Lidar and Infrared Pathfinder Satellite Observations) lidar observations. Probable mixing state of aerosols is determined utilizing the aerosol optical properties viz., aerosol optical depth, single scattering albedo and asymmetry parameter. The coated-sphere Mie calculation requires the refractive index of core and shell species, and the radius of core and shell particles. Core to shell radius

  3. Determination of aerosol ammonium using an aerodyne aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Toohey, D. W.; Worsnop, D. R.

    2003-04-01

    The chemical composition of fine aerosols is a significant issue both because it influences the chemical and radiative properties of the aerosols, which in turn impact the regional and global climate and human health, and because it is difficult to measure accurately. The Aerosol Mass Spectrometer (AMS) developed by Aerodyne Research measures both chemical composition and aerodynamic size of submicron aerosols quantitatively. However, the measurement of aerosol ammonium is more difficult than that of the other major inorganic species, nitrate and sulfate, because of interferences in the mass spectrum from air and water. This presentation will describe the successful procedure developed for dealing with these interferences and accurately determining the ammonium mass. In addition, the application of this procedure to aerosols from a range of ambient conditions will be demonstrated using data from several field studies.

  4. WANTED: Fully Automated Indexing.

    ERIC Educational Resources Information Center

    Purcell, Royal

    1991-01-01

    Discussion of indexing focuses on the possibilities of fully automated indexing. Topics discussed include controlled indexing languages such as subject heading lists and thesauri, free indexing languages, natural indexing languages, computer-aided indexing, expert systems, and the need for greater creativity to further advance automated indexing.…

  5. 3D aerosol climatology over East Asia derived from CALIOP observations

    NASA Astrophysics Data System (ADS)

    Zhou, Yongbo; Sun, Xuejin; Zhang, Chuanliang; Zhang, Riwei; Li, Yan; Li, Haoran

    2017-03-01

    The seasonal mean extinction coefficient profile (ECP), single scattering albedo (SSA), and scattering phase function (SPF) derived from the CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) version 3 Level 2 5-km aerosol profile product (2011-2014) were compiled into a three-dimensional (3D) aerosol climatology for East Asia. The SSA and SPF were calculated as the weighted averages of the scattering properties of the CALIOP aerosol subtypes. The weights were set to the occurrence frequencies of the subtypes. The single scattering properties of each subtype were extrapolated from the volume-based size distribution and complex refractive indexes based on Mie calculations. For the high-loading episodes (aerosol optical depth ≥ 0.6), the exponential ECP structures were most frequently observed over the farmland and desert areas, along with the uplifted ECP structures over the marine and coastal areas. Besides the desert areas, high-loading episodes also occurred over areas with frequent agricultural and industry activities. Unlike the conventional half-3D aerosol climatology (vertically constant SSA and SPF), this newly generated climatology specified SSA and SPF in the full-3D space (full-3D aerosol climatology). Errors on the shortwave radiative heating rate (SW RHR) due to the half-3D aerosol climatology approximation were quantified. The SW RHR errors were around ±1 K/day, implying that the half-3D aerosol climatology should be used with caution in climate modeling. This study is among the first to generate a full-3D aerosol climatology from the CALIOP data. This full-3D aerosol climatology is potentially useful for aerosol remote sensing and climate modeling.

  6. Simultaneous Retrieval of Aerosol and Cloud Properties During the MILAGRO Field Campaign

    NASA Technical Reports Server (NTRS)

    Knobelspiesse, K.; Cairns, B.; Redemann, J.; Bergstrom, R. W.; Stohl, A.

    2011-01-01

    Estimation of Direct Climate Forcing (DCF) due to aerosols in cloudy areas has historically been a difficult task, mainly because of a lack of appropriate measurements. Recently, passive remote sensing instruments have been developed that have the potential to retrieve both cloud and aerosol properties using polarimetric, multiple view angle, and multi spectral observations, and therefore determine DCF from aerosols above clouds. One such instrument is the Research Scanning Polarimeter (RSP), an airborne prototype of a sensor on the NASA Glory satellite, which unfortunately failed to reach orbit during its launch in March of 2011. In the spring of 2006, the RSP was deployed on an aircraft based in Veracruz, Mexico, as part of the Megacity Initiative: Local and Global Research Observations (MILAGRO) field campaign. On 13 March, the RSP over flew an aerosol layer lofted above a low altitude marine stratocumulus cloud close to shore in the Gulf of Mexico. We investigate the feasibility of retrieving aerosol properties over clouds using these data. Our approach is to first determine cloud droplet size distribution using the angular location of the cloud bow and other features in the polarized reflectance. The selected cloud was then used in a multiple scattering radiative transfer model optimization to determine the aerosol optical properties and fine tune the cloud size distribution. In this scene, we were able to retrieve aerosol optical depth, the fine mode aerosol size distribution parameters and the cloud droplet size distribution parameters to a degree of accuracy required for climate modeling. This required assumptions about the aerosol vertical distribution and the optical properties of the coarse aerosol size mode. A sensitivity study was also performed to place this study in the context of future systematic scanning polarimeter observations, which found that the aerosol complex refractive index can also be observed accurately if the aerosol optical depth is

  7. Aerosol optical and microphysical properties from POLDER-PARASOL multi-angle photo-polarimetric measurements

    NASA Astrophysics Data System (ADS)

    Hasekamp, O.; Litvinov, P.; Butz, A.

    2010-12-01

    The large uncertainty on the aerosol effects on clouds and climate is reflected in considerable discrepancies between different model simulations of the radiative forcing caused by these effects. Also, there exist even larger differences between values for radiative forcing calculated by models and those estimated from satellites (and model calculations constrained by satellite measurements). Relationships between aerosols and clouds derived from satellite measurements are subject to a number of important limitations. First of all, with current satellite aerosol products it is hard to determine which fraction of the aerosols is anthropogenic and which fraction is natural. Often the rather crude assumption is used that the fine mode contribution is fully anthropogenic. Furthermore, most aerosol types are strongly hygroscopic, which means that in an environment with high relative humidity (in the surrounding of clouds) the particle size increases considerably leading, in turn, to an increase in optical thickness. This effect may be misinterpreted as an apparent relation between aerosol concentration and cloud cover. Also, meteorology effects can be misinterpreted as apparent aerosol-cloud relationships. Accurate information on aerosol size and refractive index (related to chemical composition of aerosols and absorption) is needed to distinguish between natural and anthropogenic aerosols and to distinguish between aerosol effects on cloud formation and apparent relationships due to humidity and meteorology effects. Multi-angle photopolarimetric measurements have the potential to provide the necessary information on these aerosol properties. The POLDER instrument onboard the PARASOL micro-satellite is the only instrument currently in space that performs multi-angle photopolarimetric measurements. To fully exploit the information contained in these measurements a new type of retrieval algorithm is needed that retrieves detailed information on aerosol microphysical and

  8. Atmospheric effects on the NDVI - Strategies for its removal. [Normalized Difference Vegetation Index

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Tanre, D.; Holben, B. N.; Markham, B.; Gitelson, A.

    1992-01-01

    The compositing technique used to derive global vegetation index (NDVI) from the NOAA AVHRR radiances reduces the residual effect of water vapor and aerosol on the NDVI. The reduction in the atmospheric effect is shown using a comprehensive measured data set for desert conditions, and a simulation for grass with continental aerosol. A statistical analaysis of the probability of occurrence of aerosol optical thickness and precipitable water vapor measured in different climatic regimes is used for this simulation. It is concluded that for a long compositing period (e.g., 27 days), the residual aerosol optical thickness and precipitable water vapor are usually too small to be corrected. For a 9-day compositing, the residual average aerosol effect may be about twice the correction uncertainty. For Landsat TM or Earth Observing System Moderate Resolution Imaging Spectrometer (EOS-MODIS) data, the newly defined atmospherically resistant vegetation index (ARVI) is more promising than possible direct atmospheric correction schemes, except for heavy desert dust conditions.

  9. Charicteristics of Aerosol indices distribution followed by Aerosol types

    NASA Astrophysics Data System (ADS)

    Park, S.; Kim, J.; Lee, J.; Kim, M.; Lee, S.; Song, C.

    2010-12-01

    Transboundary transport of aerosol has been a hot issue in East Asia and with various aerosol types from different source region. To detect signals from aerosols, OMI provides aerosol indices. Aerosol Indices (AI) represent the change of spectral contrast between two wavelengths and these indices are derived in UV and Visible regions. These indices also can get not only in ocean but also in land region so that AI is good to observe the source region and transport of aerosols. In UV region, AI (UV-AI) can classify the absorbing and non-absorbing aerosols (Torres et al., 1998) so that this value is frequently used for dust detection. Additionally, visible AI (VIS-AI) uses to differentiate the absorbing and non-absorbing aerosol types. If we combine two types of indices at the coordinate system of two types of AI, distribution of indices contains different signals if aerosol types change theoretically. In this study, we want to find out classification results based by the observation data to see the theoretical distribution in two AI values. For the observation data, aerosol types are obtained from the results of MODIS-OMI algorithm and 4-channel algorithm classify four types of aerosols, i.e. dust, carbonaceous, sea-salt and Non-Absorbing (NA). These algorithms classify aerosol by using the characteristics of aerosol optical properties in visible and near IR regions. MODIS-OMI algorithm uses the MODIS AOD and UV-AI in OMI values. For UV-AI case, dust and carbonaceous types have larger UV-AI values than non-absorbing aerosols because of absorbing characteristics. However, dust and carbonaceous types cannot classify if UV-AI values use only. For VIS-AI case, dust has larger proportion, but carbonaceous aerosol has smaller proportion in high AI value. However, VIS-AI cannot clearly classify between dust and carbonaceous types except for the case of extremely high AI cases. In NA type, VIS-AI has almost positive values, but the distribution has smaller than the absorbing

  10. The organic aerosols of Titan

    NASA Technical Reports Server (NTRS)

    Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Suits, F.; Calcott, T. A.; Williams, M. W.; Shrader, S.; Ogino, H.; Willingham, T. O.

    1986-01-01

    A dark reddish organic solid, called tholin, is synthesized from simulated Titanian atmospheres by irradiation with high energy electrons in a plasma discharge. The visible reflection spectrum of this tholin is found to be similar to that of high altitude aerosols responsible for the albedo and reddish color of Titan. The real (n) and imaginary (k) parts of the complex refractive index of thin films of Titan prepared by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mb is determined from X-ray to microwave frequencies. Values of n (approx. 1.65) and k (approx. 0.004 to 0.08) in the visible are consistent with deductions made by groundbased and spaceborne observations of Titan. Many infrared absorption features are present in k(lambda), including the 4.6 micrometer nitrile band. Molecular analysis of the volatile components of this tholin was performed by sequential and nonsequential pyrolytic gas chromatography/mass spectrometry. More than one hundred organic compounds are released; tentative identifications include saturated and unsaturated aliphatic hydrocarbons, substituted polycylic aromatics, nitriles, amines, pyrroles, pyrazines, pyridines, pyrimidines, and the purine, adenine. In addition,acid hydrolysis produces a racemic mixture of biological and nonbiological amino acids. Many of these molecules are implicated in the origin of life on Earth, suggesting Titan as a contemporary laboratory environment for prebiological organic chemistry on a planetary scale.

  11. Introduction of the aerosol feedback process in the model BOLCHEM

    NASA Astrophysics Data System (ADS)

    Russo, Felicita; Maurizi, Alberto; D'Isidoro, Massimo; Tampieri, Francesco

    2010-05-01

    The effect of aerosols on the climate is still one of the least understood processes in the atmospheric science. The use of models to simulate the interaction between aerosols and climate can help understanding the physical processes that rule this interaction and hopefully predicting the future effects of anthropogenic aerosols on climate. In particular regional models can help study the effect of aerosols on the atmospheric dynamics on a local scale. In the work performed here we studied the feedback of aerosols in the radiative transfer calculation using the regional model BOLCHEM. The coupled meteorology-chemistry model BOLCHEM is based on the BOLAM meteorological model. The BOLAM dynamics is based on hydrostatic primitive equations, with wind components u and v, potential temperature ?, specific humidity q, surface pressure ps, as dependent variables. The vertical coordinate σ is terrain-following with variables distributed on a non-uniformly spaced staggered Lorentz grid. In the standard configuration of the model a collection of climatological aerosol optical depth values for each aerosol species is used for the radiative transfer calculation. In the feedback exercise presented here the aerosol optical depth was calculated starting from the modeled aerosol concentrations using an approximate Mie formulation described by Evans and Fournier (Evans, B.T.N. and G.R. Fournier, Applied Optics, 29, 1990). The calculation was done separately for each species and aerosol size distribution. The refractive indexes for the different species were taken from P. Stier's work (P. Stier et al., Atmos. Chem. Phys., 5, 2005) and the aerosol extinction obtained by Mie calculation were compared with the results reported by OPAC (M. Hess et al., Bull. Am. Met. Soc., 79, 1998). Two model runs, with and without the aerosol feedback, were performed to study the effects of the feedback on meteorological parameters. As a first setup of the model runs we selected a domain over the

  12. Evaluation of LIDAR/Polarimeter Aerosol Measurements by In Situ Instrumentation during DEVOTE

    NASA Astrophysics Data System (ADS)

    Beyersdorf, A. J.; Ziemba, L. D.; Anderson, B. E.; Dolgos, G.; Ottaviani, M.; Obland, M. D.; Rogers, R.; Thornhill, K. L.; Winstead, E. L.; Yang, M. M.; Hair, J. W.

    2011-12-01

    Combined measurements from LIDAR (LIght Detection And Ranging) and polarimeter instruments provide the opportunity for enhanced satellite observations of aerosol properties including retrievals of aerosol optical depth, single scattering albedo, effective radius, and refractive index. However, these retrievals (specifically for refractive index) have not been fully vetted and require additional intercomparisons with in situ measurements to improve accuracy. Proper validation of these combined LIDAR/polarimeter retrievals requires evaluation in varying atmospheric conditions and of varying aerosol composition. As part of this effort, two NASA Langley King Air aircraft have been outfitted to provide coordinated measurements of aerosol properties. One will be used as a remote sensing platform with the NASA Langley high-spectral resolution LIDAR (HSRL) and NASA GISS research scanning polarimeter (RSP). The second aircraft has been modified for use as an in situ platform and will house a suite of aerosol microphysical instrumentation, a pair of diode laser hygrometers (DLHs) for water vapor and cloud extinction measurements, and a polarized imaging nephelometer (PI-Neph). The remote sensing package has flown in a variety of campaigns, however only rarely has been able to coordinate with in situ measurements. The use of two collocated aircraft will allow for future coordinated flights to provide a more complete dataset for evaluation of aerosol retrievals and allow for fast-response capability. Results from the first coordinated King Air flights as part of DEVOTE (Development and Evaulation of satellite ValidatiOn Tools by Experimenters) will be presented. Flights are planned out of Hampton, VA during September and October 2011 including underflights of the CALIPSO satellite and overflights of ground-based AERONET (AErosol RObotic NETwork) sites. These will provide a comparison of aerosol properties between in situ and remote instruments (ground, aircraft, and satellite

  13. Aerosol Dynamics Laboratory

    SciTech Connect

    Rader, D.J.; Mondy, L.A.

    1990-04-01

    In past five years, Department 1510 has developed a state-of-the-art Aerosol Dynamics Laboratory (ADL). This report documents the current instrumentation and capabilities that exist in this laboratory. The ADL was developed from a variety of sources, with a primary contribution from Department 1510's Independent Research and Development program in aerosol dynamics. Current capabilities of the ADL include: (1) generation of calibration-quality monodisperse particles with diameters between 0.005 to 100 {mu}m, (2) real-time measurement of particle size distributions for particle diameters between 0.01 and 100 {mu}m, (3) in situ, real-time measurement of particle size distributions for particle diameters between 0.3 and 100 {mu}m, and (4) real-time measurement of particle charge distributions for particle diameters between 0.01 and 1.0 {mu}m. 14 refs., 5 figs.

  14. Aerosol Observing System (AOS) Handbook

    SciTech Connect

    Jefferson, A

    2011-01-17

    The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

  15. Satellite and ground-based study of optical properties of 1997 Indonesian Forest Fire aerosols

    NASA Astrophysics Data System (ADS)

    Nakajima, Teruyuki; Higurashi, Akiko; Takeuchi, Nobuo; Herman, Jay R.

    Optical properties of biomass burning aerosols in the event of Indonesian forest fires in 1997 were studied by groundbased sky radiometry and satellite remote sensing with AVHRR and TOMS radiometers. The AVHRR-derived optical thickness distribution agreed with the distribution of TOMS-derived UV-absorbing aerosol index and with the optical thickness measured by sky radiometry and sunphotometry. The single scattering albedo of aerosols was fairly constant as 0.9 in the September-October period. Relationship between Ångström turbidity factor and exponent supported the polydispersion consisted of aged small particles. This observation was consistent with the fact that the retrieved volume size distribution by sky radiometry has a distinct accumulation mode with a peak radius of 0.25 µm. Those optical properties of smoke aerosols seem to reflect the specific chemical structure of Indonesian forest fire aerosols, i.e., a mixture of carbonaceous and sulfate particles.

  16. Improved aerosol radiative properties as a foundation for solar geoengineering risk assessment

    NASA Astrophysics Data System (ADS)

    Dykema, J. A.; Keith, D. W.; Keutsch, F. N.

    2016-07-01

    Side effects resulting from the deliberate injection of sulfate aerosols intended to partially offset climate change have motivated the investigation of alternatives, including solid aerosol materials. Sulfate aerosols warm the tropical tropopause layer, increasing the flux of water vapor into the stratosphere, accelerating ozone loss, and increasing radiative forcing. The high refractive index of some solid materials may lead to reduction in these risks. We present a new analysis of the scattering efficiency and absorption of a range of candidate solid aerosols. We utilize a comprehensive radiative transfer model driven by updated, physically consistent estimates of optical properties. We compute the potential increase in stratospheric water vapor and associated longwave radiative forcing. We find that the stratospheric heating calculated in this analysis indicates some materials to be substantially riskier than previous work. We also find that there are Earth-abundant materials that may reduce some principal known risks relative to sulfate aerosols.

  17. Improvement of Aerosol Prediction Capability

    DTIC Science & Technology

    2001-09-30

    by dust storms in the past.) The operational aerosol products will be used for initialization or specification of aerosols in COAMPS when new cloud...Figure 2. SeaWiFS visible imagery for May 18, 2001, showing a dust storm originating at dry lakes along the Iran-Afghanistan border and then...versions of the Navy Aerosol Analysis and Prediction System (NAAPS) for analysis of airborne dust loads (Westphal/NRL). B: Modify existing radiative

  18. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2011-09-30

    Specifically, the goal is to develop a COAMPS that is capable of simulating the full range of interactions between aerosol particles, clouds , and radiative...aerosol species that are responsible for degradation of Electro- Optical (EO) propagation or that modify cloud behavior and lifetime. Report...enabling new development of more complex cloud -aerosol interactions. The work on this project has been divided into two phases, an investigation phase

  19. Photothermal spectroscopy of aerosols

    SciTech Connect

    Campillo, A.J.; Lin, H.B.

    1981-04-01

    In situ aerosol absorption spectroscopy was performed using two novel photothermal detection schemes. The first, based on a photorefractive effect and coherent detection, called phase fluctuation optical heterodyne (PFLOH) spectroscopy, could, depending on the geometry employed, yield particle specific or particle and gas absorption data. Single particles of graphite as small as 1 ..mu..m were detected in the particle specific mode. In another geometrical configuration, the total absorption (both gas and particle) of submicron sized aerosols of ammonium sulfate particles in equilibrium with gaseous ammonia and water vapor were measured at varying CO/sub 2/ laser frequencies. The specific absorption coefficient for the sulfate ion was measured to be 0.5 m/sup 2//g at 1087 cm/sup -1/. The absorption coefficient sensitivity of this scheme was less than or equal to 10/sup -8/ cm/sup -1/. The second scheme is a hybrid visible Mie scattering scheme incorporating photothermal modulation. Particle specific data on ammonium sulfate droplets were obtained. For chemically identical species, the relative absorption spectrum versus laser frequency can be obtained for polydisperse aerosol distributions directly from the data without the need for complex inverse scattering calculations.

  20. Aerosols, light, and water: Measurements of aerosol optical properties at different relative humidities

    NASA Astrophysics Data System (ADS)

    Orozco, Daniel

    (RH) at a certain RH divided by sp at a dry value, was used to evaluate the aerosol hygroscopicity. Different empirical fits were evaluated using the f(RH) data. The widely used gamma model was found inappropriate, as it overestimates f(RH) for RH<75%. Abetter empirical fit with two power-law curve-fitting parameters c and k was found to replicate f(RH) accurately from the three sites. The relationship between the organic carbon mass (OMC) and the species that are affected by RH and f(RH) was also studied and categorized between the sites. A second experiment is reported where the first two elements of the scattering matrix of laboratory generated particles were studied under different humidity conditions. The non-spherical particles generated were ammonium sulfate, sodium chloride, and ammonium nitrate. The optical measurements were performed with a polarized imaging nephelometer (PI-Neph) installed in series with the humidifier dryer apparatus. The inorganic salts experienced low (80%) RH levels so that the observations could contrast the differences when the salts were crystallized (low RH) and when the particles turned to aqueous solutions after deliquesence (high RH). The measurements with the PI-Neph produce the aerosol phase function and the polarized phase function in a range of angles that go from 3 to 177. The results showed significant changes in the phase function and polarized phase function due to the hygroscopic growth. Although the inorganic salts used inthe experiments were non-spherical, the dry measurements were successfully reproduced with the Mie theory using literature values for the dry index of refraction. Moreover, the changes in the particle size distribution and index of refraction were evaluated through classic thermodynamic equilibrium theory producing comparable results with the simulations performed with Mie formalism. The final experiment consisted in the measurements of phase function and degree of linear polarization of ambient aerosols

  1. Volcanic aerosols and lunar eclipses.

    PubMed

    Keen, R A

    1983-12-02

    The moon is visible during total lunar eclipses due to sunlight refracted into the earth's shadow by the atmosphere. Stratospheric aerosols can profoundly affect the brightness of the eclipsed moon. Observed brightnesses of 21 lunar eclipses during 1960-1982 are compared with theoretical calculations based on refraction by an aerosol-free atmosphere to yield globally averaged aerosol optical depths. Results indicate the global aerosol loading from the 1982 eruption of El Chichón is similar in magnitude to that from the 1963 Agung eruption.

  2. The NLM Indexing Initiative's Medical Text Indexer.

    PubMed

    Aronson, Alan R; Mork, James G; Gay, Clifford W; Humphrey, Susanne M; Rogers, Willie J

    2004-01-01

    The Medical Text Indexer (MTI) is a program for producing MeSH indexing recommendations. It is the major product of NLM's Indexing Initiative and has been used in both semi-automated and fully automated indexing environments at the Library since mid 2002. We report here on an experiment conducted with MEDLINE indexers to evaluate MTI's performance and to generate ideas for its improvement as a tool for user-assisted indexing. We also discuss some filtering techniques developed to improve MTI's accuracy for use primarily in automatically producing the indexing for several abstracts collections.

  3. 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.

  4. Uncertainties of simulated aerosol optical properties induced by assumptions on aerosol physical and chemical properties: An AQMEII-2 perspective

    NASA Astrophysics Data System (ADS)

    Curci, G.; Hogrefe, C.; Bianconi, R.; Im, U.; Balzarini, A.; Baró, R.; Brunner, D.; Forkel, R.; Giordano, L.; Hirtl, M.; Honzak, L.; Jiménez-Guerrero, P.; Knote, C.; Langer, M.; Makar, P. A.; Pirovano, G.; Pérez, J. L.; San José, R.; Syrakov, D.; Tuccella, P.; Werhahn, J.; Wolke, R.; Žabkar, R.; Zhang, J.; Galmarini, S.

    2015-08-01

    The calculation of aerosol optical properties from aerosol mass is a process subject to uncertainty related to necessary assumptions on the treatment of the chemical species mixing state, density, refractive index, and hygroscopic growth. In the framework of the AQMEII-2 model intercomparison, we used the bulk mass profiles of aerosol chemical species sampled over the locations of AERONET stations across Europe and North America to calculate the aerosol optical properties under a range of common assumptions for all models. Several simulations with parameters perturbed within a range of observed values are carried out for July 2010 and compared in order to infer the assumptions that have the largest impact on the calculated aerosol optical properties. We calculate that the most important factor of uncertainty is the assumption about the mixing state, for which we estimate an uncertainty of 30-35% on the simulated aerosol optical depth (AOD) and single scattering albedo (SSA). The choice of the core composition in the core-shell representation is of minor importance for calculation of AOD, while it is critical for the SSA. The uncertainty introduced by the choice of mixing state choice on the calculation of the asymmetry parameter is the order of 10%. Other factors of uncertainty tested here have a maximum average impact of 10% each on calculated AOD, and an impact of a few percent on SSA and g. It is thus recommended to focus further research on a more accurate representation of the aerosol mixing state in models, in order to have a less uncertain simulation of the related optical properties.

  5. Satellite-Based Evidence of Wavelength-Dependent Aerosol Absorption in Biomass Burning Smoke Inferred from Ozone Monitoring Instrument

    NASA Technical Reports Server (NTRS)

    Jethva, H.; Torres, O.

    2012-01-01

    We provide satellite-based evidence of the spectral dependence of absorption in biomass burning aerosols over South America using near-UV measurements made by the Ozone Monitoring Instrument (OMI) during 2005-2007. In the current near-UV OMI aerosol algorithm (OMAERUV), it is implicitly assumed that the only absorbing component in carbonaceous aerosols is black carbon whose imaginary component of the refractive index is wavelength independent. With this assumption, OMI-derived aerosol optical depth (AOD) is found to be significantly over-estimated compared to that of AERONET at several sites during intense biomass burning events (August-September). Other well-known sources of error affecting the near-UV method of aerosol retrieval do not explain the large observed AOD discrepancies between the satellite and the ground-based observations. A number of studies have revealed strong spectral dependence in carbonaceous aerosol absorption in the near-UV region suggesting the presence of organic carbon in biomass burning generated aerosols. A sensitivity analysis examining the importance of accounting for the presence of wavelength-dependent aerosol absorption in carbonaceous particles in satellite-based remote sensing was carried out in this work. The results convincingly show that the inclusion of spectrally-dependent aerosol absorption in the radiative transfer calculations leads to a more accurate characterization of the atmospheric load of carbonaceous aerosols.

  6. Can Aerosol Direct Radiative Effects Account for Analysis Increments of Temperature in the Tropical Atlantic?

    NASA Technical Reports Server (NTRS)

    da Silva, Arlindo M.; Alpert, Pinhas

    2016-01-01

    In the late 1990's, prior to the launch of the Terra satellite, atmospheric general circulation models (GCMs) did not include aerosol processes because aerosols were not properly monitored on a global scale and their spatial distributions were not known well enough for their incorporation in operational GCMs. At the time of the first GEOS Reanalysis (Schubert et al. 1993), long time series of analysis increments (the corrections to the atmospheric state by all available meteorological observations) became readily available, enabling detailed analysis of the GEOS-1 errors on a global scale. Such analysis revealed that temperature biases were particularly pronounced in the Tropical Atlantic region, with patterns depicting a remarkable similarity to dust plumes emanating from the African continent as evidenced by TOMS aerosol index maps. Yoram Kaufman was instrumental encouraging us to pursue this issue further, resulting in the study reported in Alpert et al. (1998) where we attempted to assess aerosol forcing by studying the errors of a the GEOS-1 GCM without aerosol physics within a data assimilation system. Based on this analysis, Alpert et al. (1998) put forward that dust aerosols are an important source of inaccuracies in numerical weather-prediction models in the Tropical Atlantic region, although a direct verification of this hypothesis was not possible back then. Nearly 20 years later, numerical prediction models have increased in resolution and complexity of physical parameterizations, including the representation of aerosols and their interactions with the circulation. Moreover, with the advent of NASA's EOS program and subsequent satellites, atmospheric aerosols are now monitored globally on a routine basis, and their assimilation in global models are becoming well established. In this talk we will reexamine the Alpert et al. (1998) hypothesis using the most recent version of the GEOS-5 Data Assimilation System with assimilation of aerosols. We will

  7. Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign.

    PubMed

    Collier, Sonya; Zhou, Shan; Onasch, Timothy B; Jaffe, Daniel A; Kleinman, Lawrence; Sedlacek, Arthur J; Briggs, Nicole L; Hee, Jonathan; Fortner, Edward; Shilling, John E; Worsnop, Douglas; Yokelson, Robert J; Parworth, Caroline; Ge, Xinlei; Xu, Jianzhong; Butterfield, Zachary; Chand, Duli; Dubey, Manvendra K; Pekour, Mikhail S; Springston, Stephen; Zhang, Qi

    2016-08-16

    Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (∼2700 m a.s.l.) as well as near their sources using an aircraft. The regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), an index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (∼1 h old) and emissions sampled after atmospheric transport (6-45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.

  8. Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

    DOE PAGES

    Collier, Sonya; Zhou, Shan; Onasch, Timothy B.; ...

    2016-07-11

    Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (~2700 m a.s.l.) as well as near their sources using an aircraft. In addition, the regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), anmore » index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (~1 h old) and emissions sampled after atmospheric transport (6–45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. In conclusion, these results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.« less

  9. Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

    SciTech Connect

    Collier, Sonya; Zhou, Shan; Onasch, Timothy B.; Jaffe, Daniel A.; Kleinman, Lawrence; Sedlacek, III, Arthur J.; Briggs, Nicole L.; Hee, Jonathan; Fortner, Edward; Shilling, John E.; Worsnop, Douglas; Yokelson, Robert J.; Parworth, Caroline; Ge, Xinlei; Xu, Jianzhong; Butterfield, Zachary; Chand, Duli; Dubey, Manvendra K.; Pekour, Mikhail S.; Springston, Stephen; Zhang, Qi

    2016-07-11

    Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, the regional and nearfield influences of wildfire emissions on ambient aerosol concentration and chemical properties in the Pacific Northwest region of the United States were studied using real-time measurements from a fixed ground site located in Central Oregon at the Mt. Bachelor Observatory (~2700 m a.s.l.) as well as near their sources using an aircraft. In addition, the regional characteristics of biomass burning aerosols were found to depend strongly on the modified combustion efficiency (MCE), an index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the oxidation state of organic aerosol increased with MCE and plume aging. The relationships between the aerosol properties and MCE were consistent between fresh emissions (~1 h old) and emissions sampled after atmospheric transport (6–45 h), suggesting that biomass burning organic aerosol concentration and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. In conclusion, these results suggest that MCE can be a useful metric for describing aerosol properties of wildfire emissions and their impacts on regional air quality and global climate.

  10. Comparison of Modeled Backscatter using Measured Aerosol Microphysics with Focused CW Lidar Data over Pacific

    NASA Technical Reports Server (NTRS)

    Srivastava, Vandana; Clarke, Antony D.; Jarzembski, Maurice A.; Rothermel, Jeffry

    1997-01-01

    During NASA's GLObal Backscatter Experiment (GLOBE) II flight mission over the Pacific Ocean in May-June 1990, extensive aerosol backscatter data sets from two continuous wave, focused CO2 Doppler lidars and an aerosol microphysics data set from a laser optical particle counter (LOPC) were obtained. Changes in aerosol loading in various air masses with associated changes in chemical composition, from sulfuric acid and sulfates to dustlike crustal material, significantly affected aerosol backscatter, causing variation of about 3 to 4 orders of magnitude. Some of the significant backscatter features encountered in different air masses were the low backscatter in subtropical air with even lower values in the tropics near the Intertropical Convergence Zone (ITCZ), highly variable backscatter in the ITCZ, mid-tropospheric aerosol backscatter background mode, and high backscatter in an Asian dust plume off the Japanese coast. Differences in aerosol composition and backscatter for northern and southern hemisphere also were observed. Using the LOPC measurements of physical and chemical aerosol properties, we determined the complex refractive index from three different aerosol mixture models to calculate backscatter. These values provided a well-defined envelope of modeled backscatter for various atmospheric conditions, giving good agreement with the lidar data over a horizontal sampling of approximately 18000 km in the mid-troposphere.

  11. Quantifying Above-Cloud Aerosols through Integrating Multi-Sensor Measurements from A-Train Satellites

    NASA Technical Reports Server (NTRS)

    Zhang, Yan

    2012-01-01

    Quantifying above-cloud aerosols can help improve the assessment of aerosol intercontinental transport and climate impacts. Large-scale measurements of aerosol above low-level clouds had been generally unexplored until very recently when CALIPSO lidar started to acquire aerosol and cloud profiles in June 2006. Despite CALIPSO s unique capability of measuring above-cloud aerosol optical depth (AOD), such observations are substantially limited in spatial coverage because of the lidar s near-zero swath. We developed an approach that integrates measurements from A-Train satellite sensors (including CALIPSO lidar, OMI, and MODIS) to extend CALIPSO above-cloud AOD observations to substantially larger areas. We first examine relationships between collocated CALIPSO above-cloud AOD and OMI absorbing aerosol index (AI, a qualitative measure of AOD for elevated dust and smoke aerosol) as a function of MODIS cloud optical depth (COD) by using 8-month data in the Saharan dust outflow and southwest African smoke outflow regions. The analysis shows that for a given cloud albedo, above-cloud AOD correlates positively with AI in a linear manner. We then apply the derived relationships with MODIS COD and OMI AI measurements to derive above-cloud AOD over the whole outflow regions. In this talk, we will present spatial and day-to-day variations of the above-cloud AOD and the estimated direct radiative forcing by the above-cloud aerosols.

  12. Mount Saint Helens aerosol evolution

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Farlow, N. H.; Snetsinger, K. G.; Ferry, G. V.; Fong, W.; Hayes, D. M.

    1982-01-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  13. INDOOR AEROSOLS AND EXPOSURE ASSESSMENT

    EPA Science Inventory

    This chapter provides an overview of both indoor aerosol concentration measurements, and the considerations for assessment of exposure to aerosols in non-occupational settings. The fixed-location measurements of concentration at an outdoor location, while commuting inside an a...

  14. Aerosol Variability Observed with Rpas

    NASA Astrophysics Data System (ADS)

    Altstädter, B.; Lampert, A.; Scholtz, A.; Bange, J.; Platis, A.; Hermann, M.; Wehner, B.

    2013-08-01

    To observe the origin, vertical and horizontal distribution and variability of aerosol particles, and especially ultrafine particles recently formed, we plan to employ the remotely piloted aircraft system (RPAS) Carolo-P360 "ALADINA" of TU Braunschweig. The goal of the presented project is to investigate the vertical and horizontal distribution, transport and small-scale variability of aerosol particles in the atmospheric boundary layer using RPAS. Two additional RPAS of type MASC of Tübingen University equipped with turbulence instrumentation add the opportunity to study the interaction of the aerosol concentration with turbulent transport and exchange processes of the surface and the atmosphere. The combination of different flight patterns of the three RPAS allows new insights in atmospheric boundary layer processes. Currently, the different aerosol sensors are miniaturized at the Leibniz Institute for Tropospheric Research, Leipzig and together with the TU Braunschweig adapted to fit into the RPAS. Moreover, an additional meteorological payload for measuring temperature, humidity and turbulence properties is constructed by Tübingen University. Two condensation particle counters determine the total aerosol number with a different lower detection threshold in order to investigate the horizontal and vertical aerosol variability and new particle formation (aerosol particles of some nm diameter). Further the aerosol size distribution in the range from about 0.300 to ~5 μm is given by an optical particle counter.

  15. 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.

  16. Mount St. Helens aerosol evolution

    SciTech Connect

    Oberbeck, V.R.; Farlow, N.H.

    1982-08-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mount St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  17. Mount St. Helens aerosol evolution

    SciTech Connect

    Oberbeck, V.R.; Farlow, N.H.; Fong, W.; Snetsinger, K.G.; Ferry, G.V.; Hayes, D.M.

    1982-09-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples show that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  18. Sampling stratospheric aerosols with impactors

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.

    1989-01-01

    Derivation of statistically significant size distributions from impactor samples of rarefield stratospheric aerosols imposes difficult sampling constraints on collector design. It is shown that it is necessary to design impactors of different size for each range of aerosol size collected so as to obtain acceptable levels of uncertainty with a reasonable amount of data reduction.

  19. Aerosol Remote Sensing

    NASA Technical Reports Server (NTRS)

    Lenoble, Jacqueline (Editor); Remer, Lorraine (Editor); Tanre, Didier (Editor)

    2012-01-01

    This book gives a much needed explanation of the basic physical principles of radia5tive transfer and remote sensing, and presents all the instruments and retrieval algorithms in a homogenous manner. For the first time, an easy path from theory to practical algorithms is available in one easily accessible volume, making the connection between theoretical radiative transfer and individual practical solutions to retrieve aerosol information from remote sensing. In addition, the specifics and intercomparison of all current and historical methods are explained and clarified.

  20. A novel ultrasonic aerosol generator.

    PubMed

    Davies, A; Hudson, N; Pirie, L

    1995-07-01

    An ultrasonic aerosol generator constructed from a domestic humidifier is described which has been used to produce liquid aerosols for physiological investigations. The instrument was constructed from a Pifco domestic humidifier modified to include an energy guide to direct the oscillations of the transducer through the coupling water, which would normally be aerosolized, onto a small membrane based sample chamber containing the liquid to be aerosolized. The size distribution of the aerosol produced was found to be between 2 and 6 mm, optimum for diffuse intrapulmonary deposition. Up to 4 ml/min of aqueous liquid was used; however the sample chamber could be made small enough to contain economic amounts of expensive material to administer by inhalation. The instrument has proved to be reliable over a period of three years.

  1. The Aerosol Coarse Mode Initiative

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Adhikari, N.; Air, D.; Kassianov, E.; Barnard, J.

    2014-12-01

    Many areas of the world show an aerosol volume distribution with a significant coarse mode and sometimes a dominant coarse mode. The large coarse mode is usually due to dust, but sea salt aerosol can also play an important role. However, in many field campaigns, the coarse mode tends to be ignored, because it is difficult to measure. This lack of measurements leads directly to a concomitant "lack of analysis" of this mode. Because, coarse mode aerosols can have significant effects on radiative forcing, both in the shortwave and longwave spectrum, the coarse mode -- and these forcings -- should be accounted for in atmospheric models. Forcings based only on fine mode aerosols have the potential to be misleading. In this paper we describe examples of large coarse modes that occur in areas of large aerosol loading (Mexico City, Barnard et al., 2010) as well as small loadings (Sacramento, CA; Kassianov et al., 2012; and Reno, NV). We then demonstrate that: (1) the coarse mode can contribute significantly to radiative forcing, relative to the fine mode, and (2) neglecting the coarse mode may result in poor comparisons between measurements and models. Next we describe -- in general terms -- the limitations of instrumentation to measure the coarse mode. Finally, we suggest a new initiative aimed at examining coarse mode aerosol generation mechanisms; transport and deposition; chemical composition; visible and thermal IR refractive indices; morphology; microphysical behavior when deposited on snow and ice; and specific instrumentation needs. Barnard, J. C., J. D. Fast, G. Paredes-Miranda, W. P. Arnott, and A. Laskin, 2010: Technical Note: Evaluation of the WRF-Chem "Aerosol Chemical to Aerosol Optical Properties" Module using data from the MILAGRO campaign, Atmospheric Chemistry and Physics, 10, 7325-7340. Kassianov, E. I., M. S. Pekour, and J. C. Barnard, 2012: Aerosols in Central California: Unexpectedly large contribution of coarse mode to aerosol radiative forcing

  2. Effect of Aerosols on Surface Radiation and Air Quality in the Central American Region Estimated Using Satellite UV Instruments

    NASA Astrophysics Data System (ADS)

    Bhartia, P. K.; Torres, O.; Krotkov, N. A.

    2007-05-01

    Solar radiation reaching the Earth's surface is reduced by both aerosol scattering and aerosol absorption. Over many parts of the world the latter effect can be as large or larger than the former effect, and small changes in the aerosol single scattering albedo can either cancel the former effect or enhance it. In addition, absorbing aerosols embedded in clouds can greatly reduce the amount of radiation reaching the surface by multiple scattering. Though the potential climatic effects of absorbing aerosols have received considerable attention lately, their effect on surface UV, photosynthesis, and photochemistry can be equally important for our environment and may affect human health and agricultural productivity. Absorption of all aerosols commonly found in the Earth's atmosphere becomes larger in the UV and blue wavelengths and has a relatively strong wavelength dependence. This is particularly true of mineral dust and organic aerosols. However, these effects have been very difficult to estimate on a global basis since the satellite instruments that operate in the visible are primarily sensitive to aerosol scattering. A notable exception is the UV Aerosol Index (AI), first produced using NASA's Nimbus-7 TOMS data. AI provides a direct measure of the effect of aerosol absorption on the backscattered UV radiation in both clear and cloudy conditions, as well as over snow/ice. Although many types of aerosols produce a distinct color cast in the visible images, and aerosols absorption over clouds and snow/ice could, in principle be detected from their color, so far this technique has worked well only in the UV. In this talk we will discuss what we have learned from the long-term record of AI produced from TOMS and Aura/OMI about the possible role of aerosols on surface radiation and air quality in the Central American region.

  3. How Important Is Organic Aerosol Hygroscopicity to Aerosol Indirect Forcing?

    SciTech Connect

    Liu, Xiaohong; Wang, Jian

    2010-12-07

    Organics are among the most abundant aerosol components in the atmosphere. However, there are still large uncertainties with emissions of primary organic aerosol (POA) and volatile organic compounds (VOCs) (precursor gases of secondary organic aerosol, SOA), formation and yield of SOA, and chemical and physical properties (e.g., hygroscopicity) of POA and SOA. All these may have significant impacts on aerosol direct and indirect forcing estimated from global models. In this study a modal aerosol module (MAM) in the NCAR Community Atmospheric Model (CAM) is used to examine sensitivities of aerosol indirect forcing to hygroscopicity (“κ” value) of POA and SOA. Our model simulation indicates that in the present-day condition changing “κ” value of POA from 0 to 0.1 increases the number concentration of cloud condensational nuclei (CCN) at supersaturation S=0.1% by 40-60% over the POA source regions, while changing “κ” value of SOA by ±50% (from 0.14 to 0.07 and 0.21) changes the CCN within 30%. Changes in the in-cloud droplet number concentrations (CDNC) are within 20% in most locations on the globe with the above changes in “κ” value of POA and SOA. Global annual mean anthropogenic aerosol indirect forcing (AIF) between present-day (PD) and pre-industrial (PI) conditions change by 0.4 W m-2 with the control run of -1.3 W m-2. AIF reduces with the increase hygroscopicity of organic aerosol, indicating the important role of natural organic aerosol in buffering the relative change of CDNC from PI to PD.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  6. SAGE II aerosol data validation based on retrieved aerosol model size distribution from SAGE II aerosol measurements

    NASA Technical Reports Server (NTRS)

    Wang, Pi-Huan; Mccormick, M. P.; Mcmaster, L. R.; Chu, W. P.; Swissler, T. J.; Osborn, M. T.; Russell, P. B.; Oberbeck, V. R.; Livingston, J.; Rosen, J. M.

    1989-01-01

    Consideration is given to aerosol correlative measurements experiments for the Stratospheric Aerosol and Gas Experiment (SAGE) II, conducted between November 1984 and July 1986. The correlative measurements were taken with an impactor/laser probe, a dustsonde, and an airborne 36-cm lidar system. The primary aerosol quantities measured by the ground-based instruments are compared with those calculated from the aerosol size distributions from SAGE II aerosol extinction measurements. Good agreement is found between the two sets of measurements.

  7. International Cooperative for Aerosol Prediction Workshop on Aerosol Forecast Verification

    NASA Technical Reports Server (NTRS)

    Benedetti, Angela; Reid, Jeffrey S.; Colarco, Peter R.

    2011-01-01

    The purpose of this workshop was to reinforce the working partnership between centers who are actively involved in global aerosol forecasting, and to discuss issues related to forecast verification. Participants included representatives from operational centers with global aerosol forecasting requirements, a panel of experts on Numerical Weather Prediction and Air Quality forecast verification, data providers, and several observers from the research community. The presentations centered on a review of current NWP and AQ practices with subsequent discussion focused on the challenges in defining appropriate verification measures for the next generation of aerosol forecast systems.

  8. Indexing Consistency and Quality.

    ERIC Educational Resources Information Center

    Zunde, Pranas; Dexter, Margaret E.

    A measure of indexing consistency is developed based on the concept of 'fuzzy sets'. It assigns a higher consistency value if indexers agree on the more important terms than if they agree on less important terms. Measures of the quality of an indexer's work and exhaustivity of indexing are also proposed. Experimental data on indexing consistency…

  9. Characterization of intense aerosol episodes in the Mediterranean basin from satellite observations

    NASA Astrophysics Data System (ADS)

    Gkikas, Antonis; Hatzianastassiou, Nikos; Mihalopoulos, Nikolaos

    2014-05-01

    contribution of fine to total aerosol (Fine fraction) and their UV absorption efficiency (Aerosol index). For each one of these parameters appropriate upper or lower thresholds are set and applied. According to our results, the most frequent aerosol episodes are DD, being observed in the western and central Mediterranean basin 11 (strong episodes) and 4 (extreme episodes) times/year, respectively, on average. The DD episodes yield 40% of the total number of all strong aerosol episodes, while their contribution rises up to 49% and 71.5% for all extreme episodes over land and sea, respectively. The strong episodes exhibit AOD values as high as 1.6 in the southernmost parts of central and eastern Mediterranean Sea, with values rising up to 5 for extreme episodes, mainly DD and SS. Although more than 90% of aerosol episodes last 1 day, there are few cases, mainly strong DD episodes, which last up to 6 days. Independently of their type, the Mediterranean aerosol episodes occur more frequently in spring and summer and more rarely during winter. The analysis indicates a decreasing tendency of Mediterranean aerosol episodes from 2000 to 2007. 5-days back trajectories for extreme episodes show that air masses inducing BU episodes mostly originate from Europe, those causing DD episodes primarily originate from or travel across North Africa, while SS-like episodes are associated with air masses moving across the northern Atlantic Ocean and the Mediterranean Sea.

  10. Spatio-temporal variability of aerosols in the tropics relationship with atmospheric and oceanic environments

    NASA Astrophysics Data System (ADS)

    Zuluaga-Arias, Manuel D.

    2011-12-01

    Earth's radiation budget is directly influenced by aerosols through the absorption of solar radiation and subsequent heating of the atmosphere. Aerosols modulate the hydrological cycle indirectly by modifying cloud properties, precipitation and ocean heat storage. In addition, polluting aerosols impose health risks in local, regional and global scales. In spite of recent advances in the study of aerosols variability, uncertainty in their spatio-temporal distributions still presents a challenge in the understanding of climate variability. For example, aerosol loading varies not only from year to year but also on higher frequency intraseasonal time scales producing strong variability on local and regional scales. An assessment of the impact of aerosol variability requires long period measurements of aerosols at both regional and global scales. The present dissertation compiles a large database of remotely sensed aerosol loading in order to analyze its spatio-temporal variability, and how this load interacts with different variables that characterize the dynamic and thermodynamic states of the environment. Aerosol Index (AI) and Aerosol Optical Depth (AOD) were used as measures of the atmospheric aerosol load. In addition, atmospheric and oceanic satellite observations, and reanalysis datasets is used in the analysis to investigate aerosol-environment interactions. A diagnostic study is conducted to produce global and regional aerosol satellite climatologies, and to analyze and compare the validity of aerosol retrievals. We find similarities and differences between the aerosol distributions over various regions of the globe when comparing the different satellite retrievals. A nonparametric approach is also used to examine the spatial distribution of the recent trends in aerosol concentration. A significant positive trend was found over the Middle East, Arabian Sea and South Asian regions strongly influenced by increases in dust events. Spectral and composite analyses

  11. 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

    retrieval (imaginary index of refraction, size distribution, aerosol height, particle shape). It was found that the spherical shape assumption for dust in the current retrieval is the main cause of the underestimate. In addition, it is demonstrated in an example how an incorrect assumption of the aerosol height can lead to an underestimate. Nevertheless, this is not as significant as the effect of particle shape. These findings will be incorporated in a future version of the retrieval algorithm.

  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

    varying the different assumed parameters in the retrieval (imaginary index of refraction, size distribution, aerosol height, particle shape). It was found that the spherical shape assumption for dust in the current retrieval is the main cause of the underestimate. In addition, it is demonstrated in an example how an incorrect assumption of the aerosol height can lead to an underestimate. Nevertheless, this is not as significant as the effect of particle shape. These findings will be incorporated in a future version of the retrieval algorithm.

  13. AERONET: The Aerosol Robotic Network

    DOE Data Explorer

    The AERONET (AErosol RObotic NETwork) program is a federation of ground-based remote sensing aerosol networks established by NASA and LOA-PHOTONS (CNRS) and is greatly expanded by collaborators from national agencies, institutes, universities, individual scientists, and partners. The program provides a long-term, continuous and readily accessible public domain database of aerosol optical, mircrophysical and radiative properties for aerosol research and characterization, validation of satellite retrievals, and synergism with other databases. The network imposes standardization of instruments, calibration, processing and distribution. AERONET collaboration provides globally distributed observations of spectral aerosol optical Depth (AOD), inversion products, and precipitable water in diverse aerosol regimes. Aerosol optical depth data are computed for three data quality levels: Level 1.0 (unscreened), Level 1.5 (cloud-screened), and Level 2.0 (cloud screened and quality-assured). Inversions, precipitable water, and other AOD-dependent products are derived from these levels and may implement additional quality checks.[Copied from http://aeronet.gsfc.nasa.gov/new_web/system_descriptions.html

  14. Vapor scavenging by atmospheric aerosol particles

    SciTech Connect

    Andrews, E.

    1996-05-01

    Particle growth due to vapor scavenging was studied using both experimental and computational techniques. Vapor scavenging by particles is an important physical process in the atmosphere because it can result in changes to particle properties (e.g., size, shape, composition, and activity) and, thus, influence atmospheric phenomena in which particles play a role, such as cloud formation and long range transport. The influence of organic vapor on the evolution of a particle mass size distribution was investigated using a modified version of MAEROS (a multicomponent aerosol dynamics code). The modeling study attempted to identify the sources of organic aerosol observed by Novakov and Penner (1993) in a field study in Puerto Rico. Experimentally, vapor scavenging and particle growth were investigated using two techniques. The influence of the presence of organic vapor on the particle`s hydroscopicity was investigated using an electrodynamic balance. The charge on a particle was investigated theoretically and experimentally. A prototype apparatus--the refractive index thermal diffusion chamber (RITDC)--was developed to study multiple particles in the same environment at the same time.

  15. eDPS Aerosol Collection

    SciTech Connect

    Venzie, J.

    2015-10-13

    The eDPS Aerosol Collection project studies the fundamental physics of electrostatic aerosol collection for national security applications. The interpretation of aerosol data requires understanding and correcting for biases introduced from particle genesis through collection and analysis. The research and development undertaken in this project provides the basis for both the statistical correction of existing equipment and techniques; as well as, the development of new collectors and analytical techniques designed to minimize unwanted biases while improving the efficiency of locating and measuring individual particles of interest.

  16. Aerosol growth in Titan's ionosphere.

    PubMed

    Lavvas, Panayotis; Yelle, Roger V; Koskinen, Tommi; Bazin, Axel; Vuitton, Véronique; Vigren, Erik; Galand, Marina; Wellbrock, Anne; Coates, Andrew J; Wahlund, Jan-Erik; Crary, Frank J; Snowden, Darci

    2013-02-19

    Photochemically produced aerosols are common among the atmospheres of our solar system and beyond. Observations and models have shown that photochemical aerosols have direct consequences on atmospheric properties as well as important astrobiological ramifications, but the mechanisms involved in their formation remain unclear. Here we show that the formation of aerosols in Titan's upper atmosphere is directly related to ion processes, and we provide a complete interpretation of observed mass spectra by the Cassini instruments from small to large masses. Because all planetary atmospheres possess ionospheres, we anticipate that the mechanisms identified here will be efficient in other environments as well, modulated by the chemical complexity of each atmosphere.

  17. 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.

  18. Aerosol measurement program strategy for global aerosol backscatter model development

    NASA Technical Reports Server (NTRS)

    Bowdle, David A.

    1985-01-01

    The purpose was to propose a balanced program of aerosol backscatter research leading to the development of a global model of aerosol backscatter. Such a model is needed for feasibility studies and systems simulation studies for NASA's prospective satellite-based Doppler lidar wind measurement system. Systems of this kind measure the Doppler shift in the backscatter return from small atmospheric aerosol wind tracers (of order 1 micrometer diameter). The accuracy of the derived local wind estimates and the degree of global wind coverage for such a system are limited by the local availability and by the global scale distribution of natural aerosol particles. The discussions here refer primarily to backscatter model requirements at CO2 wavelengths, which have been selected for most of the Doppler lidar systems studies to date. Model requirements for other potential wavelengths would be similar.

  19. Retrieval of Aerosol Absorption over Ocean using AATSR/MERIS

    NASA Astrophysics Data System (ADS)

    Filipitsch, Florian; Preusker, Rene; Fischer, Juergen

    2013-04-01

    surface are based on Cox and Munk. Here the glint can be described as a poor function of observing geometry, refractive index, and effective wind speed, which is true as we assume a black water body in the analysed spectral range. Hence, the calculated glint can be transferred to any other observing geometry and spectral channel of the instrument. The derivation of the optical properties of an observed aerosol layer is done by utilizing the different effects of aerosols on the signal over a highly and poorly reflecting surface. A non absorbing aerosol layer leads here to a brightening effect in the off glint and to a dimming in the glint region. Whereby a layer with the same AOD but containing an absorbing aerosol has a lower brightening effect on the off glint region and higher dimming effect on the glint area.

  20. Remote Sensing of Aerosol and Non-Aerosol Absorption

    NASA Technical Reports Server (NTRS)

    Kaufman, Y. J.; Dubovik, O.; Holben, B. N.; Remer, L. A.; Tanre, D.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Remote sensing of aerosol from the new satellite instruments (e.g. MODIS from Terra) and ground based radiometers (e.g. the AERONET) provides the opportunity to measure the absorption characteristics of the ambient undisturbed aerosol in the entire atmospheric column. For example Landsat and AERONET data are used to measure spectral absorption of sunlight by dust from West Africa. Both Application of the Landsat and AERONET data demonstrate that Saharan dust absorption of solar radiation is several times smaller than the current international standards. This is due to difficulties of measuring dust absorption in situ, and due to the often contamination of dust properties by the presence of air pollution or smoke. We use the remotely sensed aerosol absorption properties described by the spectral sin le scattering albedo, together with statistics of the monthly optical thickness for the fine and coarse aerosol derived from the MODIS data. The result is an estimate of the flux of solar radiation absorbed by the aerosol layer in different regions around the globe where aerosol is prevalent. If this aerosol forcing through absorption is not included in global circulation models, it may be interpreted as anomalous absorption in these regions. In a preliminary exercise we also use the absorption measurements by AERONET, to derive the non-aerosol absorption of the atmosphere in cloud free conditions. The results are obtained for the atmospheric windows: 0.44 microns, 0.66 microns, 0.86 microns and 1.05 microns. In all the locations over the land and ocean that were tested no anomalous absorption in these wavelengths, was found within absorption optical thickness of +/- 0.005.

  1. Aerosol lidar ``M4``

    SciTech Connect

    Shelevoy, C.D.; Andreev, Y.M. |

    1994-12-31

    Small carrying aerosol lidar in which is used small copper vapor laser ``Malachite`` as source of sounding optical pulses is described. The advantages of metal vapor laser and photon counting mode in acquisition system of lidar gave ability to get record results: when lidar has dimensions (1 x .6 x .3 m) and weight (65 kg), it provides the sounding of air industrial pollutions at up to 20 km range in scanning sector 90{degree}. Power feed is less than 800 Wt. Lidar can be disposed as stationary so on the car, helicopter, light plane. Results of location of smoke tails and city smog in situ experiments are cited. Showed advantages of work of acquisition system in photon counting mode when dynamic range of a signal is up to six orders.

  2. Stratospheric aerosol geoengineering

    SciTech Connect

    Robock, Alan

    2015-03-30

    The Geoengineering Model Intercomparison Project, conducting climate model experiments with standard stratospheric aerosol injection scenarios, has found that insolation reduction could keep the global average temperature constant, but global average precipitation would reduce, particularly in summer monsoon regions around the world. Temperature changes would also not be uniform; the tropics would cool, but high latitudes would warm, with continuing, but reduced sea ice and ice sheet melting. Temperature extremes would still increase, but not as much as without geoengineering. If geoengineering were halted all at once, there would be rapid temperature and precipitation increases at 5–10 times the rates from gradual global warming. The prospect of geoengineering working may reduce the current drive toward reducing greenhouse gas emissions, and there are concerns about commercial or military control. Because geoengineering cannot safely address climate change, global efforts to reduce greenhouse gas emissions and to adapt are crucial to address anthropogenic global warming.

  3. Maritime Aerosol Network as a component of Aerosol Robotic Network

    NASA Astrophysics Data System (ADS)

    Smirnov, A.; Holben, B. N.; Slutsker, I.; Giles, D. M.; McClain, C. R.; Eck, T. F.; Sakerin, S. M.; Macke, A.; Croot, P.; Zibordi, G.; Quinn, P. K.; Sciare, J.; Kinne, S.; Harvey, M.; Smyth, T. J.; Piketh, S.; Zielinski, T.; Proshutinsky, A.; Goes, J. I.; Nelson, N. B.; Larouche, P.; Radionov, V. F.; Goloub, P.; Krishna Moorthy, K.; Matarrese, R.; Robertson, E. J.; Jourdin, F.

    2009-03-01

    The paper presents the current status of the Maritime Aerosol Network (MAN), which has been developed as a component of the Aerosol Robotic Network (AERONET). MAN deploys Microtops handheld Sun photometers and utilizes the calibration procedure and data processing (Version 2) traceable to AERONET. A web site dedicated to the MAN activity is described. A brief historical perspective is given to aerosol optical depth (AOD) measurements over the oceans. A short summary of the existing data, collected on board ships of opportunity during the NASA Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project is presented. Globally averaged oceanic aerosol optical depth (derived from island-based AERONET measurements) at 500 nm is ˜0.11 and Angstrom parameter (computed within spectral range 440-870 nm) is calculated to be ˜0.6. First results from the cruises contributing to the Maritime Aerosol Network are shown. MAN ship-based aerosol optical depth compares well to simultaneous island and near-coastal AERONET site AOD.

  4. Evaluating model parameterizations of submicron aerosol scattering and absorption with in situ data from ARCTAS 2008

    NASA Astrophysics Data System (ADS)

    Alvarado, Matthew J.; Lonsdale, Chantelle R.; Macintyre, Helen L.; Bian, Huisheng; Chin, Mian; Ridley, David A.; Heald, Colette L.; Thornhill, Kenneth L.; Anderson, Bruce E.; Cubison, Michael J.; Jimenez, Jose L.; Kondo, Yutaka; Sahu, Lokesh K.; Dibb, Jack E.; Wang, Chien

    2016-07-01

    Accurate modeling of the scattering and absorption of ultraviolet and visible radiation by aerosols is essential for accurate simulations of atmospheric chemistry and climate. Closure studies using in situ measurements of aerosol scattering and absorption can be used to evaluate and improve models of aerosol optical properties without interference from model errors in aerosol emissions, transport, chemistry, or deposition rates. Here we evaluate the ability of four externally mixed, fixed size distribution parameterizations used in global models to simulate submicron aerosol scattering and absorption at three wavelengths using in situ data gathered during the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign. The four models are the NASA Global Modeling Initiative (GMI) Combo model, GEOS-Chem v9-02, the baseline configuration of a version of GEOS-Chem with online radiative transfer calculations (called GC-RT), and the Optical Properties of Aerosol and Clouds (OPAC v3.1) package. We also use the ARCTAS data to perform the first evaluation of the ability of the Aerosol Simulation Program (ASP v2.1) to simulate submicron aerosol scattering and absorption when in situ data on the aerosol size distribution are used, and examine the impact of different mixing rules for black carbon (BC) on the results. We find that the GMI model tends to overestimate submicron scattering and absorption at shorter wavelengths by 10-23 %, and that GMI has smaller absolute mean biases for submicron absorption than OPAC v3.1, GEOS-Chem v9-02, or GC-RT. However, the changes to the density and refractive index of BC in GC-RT improve the simulation of submicron aerosol absorption at all wavelengths relative to GEOS-Chem v9-02. Adding a variable size distribution, as in ASP v2.1, improves model performance for scattering but not for absorption, likely due to the assumption in ASP v2.1 that BC is present at a constant mass fraction

  5. The regime of biomass burning aerosols over the Mediterranean basin based on satellite observations

    NASA Astrophysics Data System (ADS)

    Kalaitzi, Nikoleta; Gkikas, Antonis; Papadimas, Christos. D.; Hatzianastassiou, Nikolaos; Torres, Omar; Mihalopoulos, Nikolaos

    2016-04-01

    specifically, the algorithm examines the fulfillment of these criteria for Ångström Exponent (AE), Fine Fraction (FF) and Aerosol Index (AI). The AE and FF data, which are characteristic of the aerosol size, are derived from multispectralCollection 006 MODIS-AquaAerosol Optical Depth (AOD) data, whereas the AI data, that characterize the absorption ability of aerosols, are taken from the OMI-Aura database. The algorithm enables the identification of BB aerosols over specific geographical cells (pixels) throughout the study region, over both sea and land surfaces, during days of the 2005-2015 period. The results make possible the construction of a climatological-like database of Mediterranean BB aerosols, permitting to perceive the geographical patterns of their regime, namely the areas in which they occur, in relation to their timing, i.e. the months and seasons of their occurrence. This regime is quantified, which means that the frequency (absolute and percent) of occurrence of BB aerosols is calculated, along with the associated computed AOD values. The year by year variability of BB aerosols is also investigated over the period 2005-2015, with emphasis to inter-annual and seasonal tendencies.

  6. Stratospheric aerosols and climatic change

    NASA Technical Reports Server (NTRS)

    Baldwin, B.; Pollack, J. B.; Summers, A.; Toon, O. B.; Sagan, C.; Van Camp, W.

    1976-01-01

    Generated primarily by volcanic explosions, a layer of submicron silicate particles and particles made of concentrated sulfuric acids solution is present in the stratosphere. Flights through the stratosphere may be a future source of stratospheric aerosols, since the effluent from supersonic transports contains sulfurous gases (which will be converted to H2SO4) while the exhaust from Space Shuttles contains tiny aluminum oxide particles. Global heat balance calculations have shown that the stratospheric aerosols have made important contributions to some climatic changes. In the present paper, accurate radiative transfer calculations of the globally-averaged surface temperature (T) are carried out to estimate the sensitivity of the climate to changes in the number of stratospheric aerosols. The results obtained for a specified model atmosphere, including a vertical profile of the aerosols, indicate that the climate is unlikely to be affected by supersonic transports and Space Shuttles, during the next decades.

  7. Satellite measurements of tropospheric aerosols

    NASA Technical Reports Server (NTRS)

    Griggs, M.

    1981-01-01

    This investigation uses LANDSAT 2 radiance data and ground-truth measurements of the aerosol optical thickness, obtained previously from five inland sites, to study the usefulness and limitations of the near infrared radiance over inland bodies of water. The linear relationship between LANDSAT 2 MSS7 and aerosol content found in this study can be used to estimate the aerosol content with a standard deviation of 0.42N. Analysis of the data for MSS6 and MSS7 suggest that the larger uncertainty is mostly due to water turbidity, with little contribution from the adjacency effect. The relationship found is best applied to determine an average aerosol content over a period of time at a given target, or an area average at a given time over several targets close together.

  8. Wind Power Charged Aerosol Generator

    SciTech Connect

    Marks, A.M.

    1980-07-01

    This describes experimental results on a Charged Aerosol Wind/Electric Power Generator, using Induction Electric Charging with a water jet issuing under water pressure from a small diameter (25-100 ..mu..m) orifice.

  9. Effect of aerosol subgrid variability on aerosol optical depth and cloud condensation nuclei: implications for global aerosol modelling

    NASA Astrophysics Data System (ADS)

    Weigum, Natalie; Schutgens, Nick; Stier, Philip

    2016-11-01

    A fundamental limitation of grid-based models is their inability to resolve variability on scales smaller than a grid box. Past research has shown that significant aerosol variability exists on scales smaller than these grid boxes, which can lead to discrepancies in simulated aerosol climate effects between high- and low-resolution models. This study investigates the impact of neglecting subgrid variability in present-day global microphysical aerosol models on aerosol optical depth (AOD) and cloud condensation nuclei (CCN). We introduce a novel technique to isolate the effect of aerosol variability from other sources of model variability by varying the resolution of aerosol and trace gas fields while maintaining a constant resolution in the rest of the model. We compare WRF-Chem (Weather and Research Forecast model) runs in which aerosol and gases are simulated at 80 km and again at 10 km resolutions; in both simulations the other model components, such as meteorology and dynamics, are kept at the 10 km baseline resolution. We find that AOD is underestimated by 13 % and CCN is overestimated by 27 % when aerosol and gases are simulated at 80 km resolution compared to 10 km. The processes most affected by neglecting aerosol subgrid variability are gas-phase chemistry and aerosol uptake of water through aerosol-gas equilibrium reactions. The inherent non-linearities in these processes result in large changes in aerosol properties when aerosol and gaseous species are artificially mixed over large spatial scales. These changes in aerosol and gas concentrations are exaggerated by convective transport, which transports these altered concentrations to altitudes where their effect is more pronounced. These results demonstrate that aerosol variability can have a large impact on simulating aerosol climate effects, even when meteorology and dynamics are held constant. Future aerosol model development should focus on accounting for the effect of subgrid variability on these

  10. Seasonal variability of aerosol optical depth over Indian subcontinent

    USGS Publications Warehouse

    Prasad, A.K.; Singh, R.P.; Singh, A.; Kafatos, M.

    2005-01-01

    Ganga basin extends 2000 km E-W and about 400 km N-S and is bounded by Himalayas in the north. This basin is unequivocally found to be affected by high aerosols optical depth (AOD) (>0.6) throughout the year. Himalayas restricts movement of aerosols toward north and as a result dynamic nature of aerosol is seen over the Ganga basin. High AOD in this region has detrimental effects on health of more than 460 million people living in this part of India besides adversely affecting clouds formation, monsoonal rainfall pattern and Normalized Difference Vegetation Index (NDVI). Severe drought events (year 2002) in Ganga basin and unexpected failure of monsoon several times, occurred in different parts of Indian subcontinent. Significant rise in AOD (18.7%) over the central part of basin (Kanpur region) have been found to cause substantial decrease in NDVI (8.1%) since 2000. A negative relationship is observed between AOD and NDVI, magnitude of which differs from region to region. Efforts have been made to determine general distribution of AOD and its dominant departure in recent years spatially using Moderate Resolution Imaging Spectroradiometer (MODIS) data. The seasonal changes in aerosol optical depth over the Indo-Gangetic basin is found to very significant as a result of the increasing dust storm events in recent years. ?? 2005 IEEE.

  11. A new approach for retrieving the UV-vis optical properties of ambient aerosols

    NASA Astrophysics Data System (ADS)

    Bluvshtein, Nir; Flores, J. Michel; Segev, Lior; Rudich, Yinon

    2016-08-01

    Atmospheric aerosols play an important part in the Earth's energy budget by scattering and absorbing incoming solar and outgoing terrestrial radiation. To quantify the effective radiative forcing due to aerosol-radiation interactions, researchers must obtain a detailed understanding of the spectrally dependent intensive and extensive optical properties of different aerosol types. Our new approach retrieves the optical coefficients and the single-scattering albedo of the total aerosol population over 300 to 650 nm wavelength, using extinction measurements from a broadband cavity-enhanced spectrometer at 315 to 345 nm and 390 to 420 nm, extinction and absorption measurements at 404 nm from a photoacoustic cell coupled to a cavity ring-down spectrometer, and scattering measurements from a three-wavelength integrating nephelometer. By combining these measurements with aerosol size distribution data, we retrieved the time- and wavelength-dependent effective complex refractive index of the aerosols. Retrieval simulations and laboratory measurements of brown carbon proxies showed low absolute errors and good agreement with expected and reported values. Finally, we implemented this new broadband method to achieve continuous spectral- and time-dependent monitoring of ambient aerosol population, including, for the first time, extinction measurements using cavity-enhanced spectrometry in the 315 to 345 nm UV range, in which significant light absorption may occur.

  12. Regional Influence of Aerosol Emissions from Wildfires Driven by Combustion Efficiency: Insights from the BBOP Campaign

    SciTech Connect

    Collier, Sonya; Zhou, Shan; Onasch, Timothy B.; Jaffe, Daniel A.; Kleinman, Lawrence; Sedlacek, Arthur J.; Briggs, Nicole L.; Hee, Jonathan; Fortner, Edward; Shilling, John E.; Worsnop, Douglas; Yokelson, Robert J.; Parworth, Caroline; Ge, Xinlei; Xu, Jianzhong; Butterfield, Zachary; Chand, Duli; Dubey, Manvendra K.; Pekour, Mikhail S.; Springston, Stephen; Zhang, Qi

    2016-08-16

    Abstract Wildfires are important contributors to atmospheric aerosols and a large source of emissions that impact regional air quality and global climate. In this study, wildfire emissions in the Pacific Northwest region of the United States were characterized using real-time measurements near their sources using an aircraft, and farther downwind from a fixed ground site located at the Mt. Bachelor Observatory (~ 2700 m a.s.l.). The characteristics of aerosol emissions were found to depend strongly on the modified combustion efficiency (MCE), a qualitative index of the combustion processes of a fire. Organic aerosol emissions had negative correlations with MCE, whereas the carbon oxidation state of organic aerosol increased with MCE. The relationships between the aerosol properties and MCE were consistent between fresher emissions (~1 hour old) and emissions sampled after atmospheric transport (6 - 45 hours), suggesting that organic aerosol mass loading and chemical properties were strongly influenced by combustion processes at the source and conserved to a significant extent during regional transport. These results suggest that MCE can be a useful metric for describing aerosol properties of regionally transported wildfire emissions and their impacts on regional air quality and global climate.

  13. Measurement-based estimates of direct radiative effects of absorbing aerosols above clouds

    NASA Astrophysics Data System (ADS)

    Feng, Nan; Christopher, Sundar A.

    2015-07-01

    The elevated layers of absorbing smoke aerosols from western African (e.g., Gabon and Congo) biomass burning activities have been frequently observed above low-level stratocumulus clouds off the African coast, which presents an excellent natural laboratory for studying the effects of aerosols above clouds (AAC) on regional energy balance in tropical and subtropical environments. Using spatially and temporally collocated Moderate Resolution Imaging Spectroradiometer, Ozone Monitoring Instrument (OMI), and Clouds and the Earth's Radiant Energy System data sets, the top-of-atmosphere shortwave aerosol direct shortwave radiative effects (ARE) of absorbing aerosols above low-level water clouds in the southeast Atlantic Ocean was examined in this study. The regional averaged instantaneous ARE has been estimated to be 36.7 ± 20.5 Wm-2 (regional mean ± standard deviation) along with a mean positive OMI Aerosol Index at 1.3 in August 2006 based on multisensors measurements. The highest magnitude of instantaneous ARE can even reach 138.2 Wm-2. We assess that the 660 nm cloud optical depth (COD) values of 8-12 is the critical value above (below) which aerosol absorption (scattering) effect dominates and further produces positive (negative) ARE values. The results further show that ARE values are more sensitive to aerosols above lower COD values than cases for higher COD values. This is among the first studies to provide quantitative estimates of shortwave ARE due to AAC events from an observational perspective.

  14. Porous aerosol in degassing plumes of Mt. Etna and Mt. Stromboli

    NASA Astrophysics Data System (ADS)

    Shcherbakov, Valery; Jourdan, Olivier; Voigt, Christiane; Gayet, Jean-Francois; Chauvigne, Aurélien; Schwarzenboeck, Alfons; Minikin, Andreas; Klingebiel, Marcus; Weigel, Ralf; Borrmann, Stephan; Jurkat, Tina; Kaufmann, Stefan; Schlage, Romy; Gourbeyre, Christophe; Febvre, Guy; Lapyonok, Tatyana; Frey, Wiebke; Molleker, Sergej; Weinzierl, Bernadett

    2016-09-01

    Aerosols of the volcanic degassing plumes from Mt. Etna and Mt. Stromboli were probed with in situ instruments on board the Deutsches Zentrum für Luft- und Raumfahrt research aircraft Falcon during the contrail, volcano, and cirrus experiment CONCERT in September 2011. Aerosol properties were analyzed using angular-scattering intensities and particle size distributions measured simultaneously with the Polar Nephelometer and the Forward Scattering Spectrometer probes (FSSP series 100 and 300), respectively. Aerosols of degassing plumes are characterized by low values of the asymmetry parameter (between 0.6 and 0.75); the effective diameter was within the range of 1.5-2.8 µm and the maximal diameter was lower than 20 µm. A principal component analysis applied to the Polar Nephelometer data indicates that scattering features of volcanic aerosols of different crater origins are clearly distinctive from angular-scattering intensities of cirrus and contrails. Retrievals of aerosol properties revealed that the particles were "optically spherical" and the estimated values of the real part of the refractive index are within the interval from 1.35 to 1.38. The interpretation of these results leads to the conclusion that the degassing plume aerosols were porous with air voids. Our estimates suggest that aerosol particles contained about 18 to 35 % of air voids in terms of the total volume.

  15. New Satellite Measurements of Aerosol Direct Radiative Forcing from MODIS, MISR, and POLDER

    NASA Technical Reports Server (NTRS)

    Kaufman, Y.

    2000-01-01

    New set of satellites, MODIS and MISR launched on EOS-Terra and POLDER launched on ADEOS-1, and scheduled for ADEOS-II and PARASOL in orbit with EOS-AQUA, open exciting opportunities to measure aerosol and their radiative forcing of climate. Each of these instruments has a different approach to invert remote sensing data to derive the aerosol properties. MODIS is using wide spectral range 0.47-2.1 micron. MISR is using narrower spectral range (0.44 to 0.87 micron) but observing the same spot from 9 different angles along the satellite track. POLDER using similar wavelengths, uses two dimensional view with a wide angle optics and adds polarization to the inversion process. Among these instruments, we expect to measure the global distribution of aerosol, to distinguish small pollution particles from large particles from deserts and ocean spray. We shall try to measure the aerosol absorption of solar radiation, and their refractive index that indicates the effect of liquid water on the aerosol size and interaction with sunlight. The radiation field measured by these instruments in variety of wavelengths and angles, is also used to derive the effect of the aerosol on reflection of sunlight spectral fluxes to space. When combined with flux measurements at the ground, it gives a complete characterization of the effect of aerosol on solar illumination, heating in the atmosphere and reflection to space.

  16. Infrared limb emission measurements of aerosol in the troposphere and stratosphere

    NASA Astrophysics Data System (ADS)

    Griessbach, Sabine; Hoffmann, Lars; Spang, Reinhold; von Hobe, Marc; Müller, Rolf; Riese, Martin

    2016-09-01

    Altitude-resolved aerosol detection in the upper troposphere and lower stratosphere (UTLS) is a challenging task for remote sensing instruments. Infrared limb emission measurements provide vertically resolved global measurements at day- and nighttime in the UTLS. For high-spectral-resolution infrared limb instruments we present here a new method to detect aerosol and separate between ice and non-ice particles. The method is based on an improved aerosol-cloud index that identifies infrared limb emission spectra affected by non-ice aerosol or ice clouds. For the discrimination between non-ice aerosol and ice clouds we employed brightness temperature difference correlations. The discrimination thresholds for this method were derived from radiative transfer simulations (including scattering) and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS)/Envisat measurements obtained in 2011. We demonstrate the value of this approach for observations of volcanic ash and sulfate aerosol originating from the Grímsvötn (Iceland, 64° N), Puyehue-Cordón Caulle (Chile, 40° S), and Nabro (Eritrea, 13° N) eruptions in May and June 2011 by comparing the MIPAS volcanic aerosol detections with Atmospheric Infrared Sounder (AIRS) volcanic ash and SO2 measurements.

  17. Method for producing monodisperse aerosols

    DOEpatents

    Ortiz, Lawrence W.; Soderholm, Sidney C.

    1990-01-01

    An aerosol generator is described which is capable of producing a monodisperse aerosol within narrow limits utilizing an aqueous solution capable of providing a high population of seed nuclei and an organic solution having a low vapor pressure. The two solutions are cold nebulized, mixed, vaporized, and cooled. During cooling, particles of the organic vapor condense onto the excess seed nuclei, and grow to a uniform particle size.

  18. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2016-06-13

    storm activity, and 4) surface and airborne measurements on the west coast of the U.S. indicate the presence of aerosols and dust on the predicted...observables (in situ and satellites) and model quantities such as mass. Aerosol species currently included in the analyses are dust , pollution, biomass...Prediction System ( COAMPS ®). Over the next several years it is the goal of this project to maintain these systems as the world leaders in EO prediction

  19. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2016-06-07

    for dust storm forecasting and analysis, AGU Fall Meeting, San Francisco, CA. Dec. 11-15, 2002 [Published]. Reid, J.S., J.R. Cook, D.L. Westphal...Persian Gulf/Arabian Sea, East Asia, and some parts of the Mediterranean Sea. Along coastal regions, dust , pollution and smoke can be present and...transitioned from the combined Marine Aerosol and Dust Aerosol programs from SPAWAR Systems Center San Diego (SSC-SD) to the Naval Research Laboratory

  20. AEROSOL, CLOUDS, AND CLIMATE CHANGE

    SciTech Connect

    SCHWARTZ, S.E.

    2005-09-01

    Earth's climate is thought to be quite sensitive to changes in radiative fluxes that are quite small in absolute magnitude, a few watts per square meter, and in relation to these fluxes in the natural climate. Atmospheric aerosol particles exert influence on climate directly, by scattering and absorbing radiation, and indirectly by modifying the microphysical properties of clouds and in turn their radiative effects and hydrology. The forcing of climate change by these indirect effects is thought to be quite substantial relative to forcing by incremental concentrations of greenhouse gases, but highly uncertain. Quantification of aerosol indirect forcing by satellite- or ground-based remote sensing has proved quite difficult in view of inherent large variation in the pertinent observables such as cloud optical depth, which is controlled mainly by liquid water path and only secondarily by aerosols. Limited work has shown instances of large magnitude of aerosol indirect forcing, with local instantaneous forcing upwards of 50 W m{sup 66}-2. Ultimately it will be necessary to represent aerosol indirect effects in climate models to accurately identify the anthropogenic forcing at present and over secular time and to assess the influence of this forcing in the context of other forcings of climate change. While the elements of aerosol processes that must be represented in models describing the evolution and properties of aerosol particles that serve as cloud condensation particles are known, many important components of these processes remain to be understood and to be represented in models, and the models evaluated against observation, before such model-based representations can confidently be used to represent aerosol indirect effects in climate models.

  1. Estimates of the aerosol indirect effect over the Baltic Sea region derived from 12 years of MODIS observations

    NASA Astrophysics Data System (ADS)

    Saponaro, Giulia; Kolmonen, Pekka; Sogacheva, Larisa; Rodriguez, Edith; Virtanen, Timo; de Leeuw, Gerrit

    2017-02-01

    Retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) on-board the Aqua satellite, 12 years (2003-2014) of aerosol and cloud properties were used to statistically quantify aerosol-cloud interaction (ACI) over the Baltic Sea region, including the relatively clean Fennoscandia and the more polluted central-eastern Europe. These areas allowed us to study the effects of different aerosol types and concentrations on macro- and microphysical properties of clouds: cloud effective radius (CER), cloud fraction (CF), cloud optical thickness (COT), cloud liquid water path (LWP) and cloud-top height (CTH). Aerosol properties used are aerosol optical depth (AOD), Ångström exponent (AE) and aerosol index (AI). The study was limited to low-level water clouds in the summer. The vertical distributions of the relationships between cloud properties and aerosols show an effect of aerosols on low-level water clouds. CF, COT, LWP and CTH tend to increase with aerosol loading, indicating changes in the cloud structure, while the effective radius of cloud droplets decreases. The ACI is larger at relatively low cloud-top levels, between 900 and 700 hPa. Most of the studied cloud variables were unaffected by the lower-tropospheric stability (LTS), except for the cloud fraction. The spatial distribution of aerosol and cloud parameters and ACI, here defined as the change in CER as a function of aerosol concentration for a fixed LWP, shows positive and statistically significant ACI over the Baltic Sea and Fennoscandia, with the former having the largest values. Small negative ACI values are observed in central-eastern Europe, suggesting that large aerosol concentrations saturate the ACI.

  2. Inverse atmospheric radiative transfer problems - A nonlinear minimization search method of solution. [aerosol pollution monitoring

    NASA Technical Reports Server (NTRS)

    Fymat, A. L.

    1976-01-01

    The paper studies the inversion of the radiative transfer equation describing the interaction of electromagnetic radiation with atmospheric aerosols. The interaction can be considered as the propagation in the aerosol medium of two light beams: the direct beam in the line-of-sight attenuated by absorption and scattering, and the diffuse beam arising from scattering into the viewing direction, which propagates more or less in random fashion. The latter beam has single scattering and multiple scattering contributions. In the former case and for single scattering, the problem is reducible to first-kind Fredholm equations, while for multiple scattering it is necessary to invert partial integrodifferential equations. A nonlinear minimization search method, applicable to the solution of both types of problems has been developed, and is applied here to the problem of monitoring aerosol pollution, namely the complex refractive index and size distribution of aerosol particles.

  3. Aerosol Retrieval from Multiangle Multispectral Photopolarimetric Measurements: Importance of Spectral Range and Angular Resolution

    NASA Technical Reports Server (NTRS)

    Wu, L.; Hasekamp, O.; Van Diedenhoven, B.; Cairns, B.

    2015-01-01

    We investigated the importance of spectral range and angular resolution for aerosol retrieval from multiangle photopolarimetric measurements over land. For this purpose, we use an extensive set of simulated measurements for different spectral ranges and angular resolutions and subsets of real measurements of the airborne Research Scanning Polarimeter (RSP) carried out during the PODEX and SEAC4RS campaigns over the continental USA. Aerosol retrievals performed from RSP measurements show good agreement with ground-based AERONET measurements for aerosol optical depth (AOD), single scattering albedo (SSA) and refractive index. Furthermore, we found that inclusion of shortwave infrared bands (1590 and/or 2250 nm) significantly improves the retrieval of AOD, SSA and coarse mode microphysical properties. However, accuracies of the retrieved aerosol properties do not improve significantly when more than five viewing angles are used in the retrieval.

  4. An Overview of the GEOS-5 Aerosol Reanalysis

    NASA Astrophysics Data System (ADS)

    da Silva, A.; Colarco, P. R.; Darmenov, A. S.; Buchard-Marchant, V.; Randles, C. A.; Gupta, P.

    2011-12-01

    global scale, we perform a detailed radiative transfer calculation to simulate the UV aerosol index, comparing our results to OMI measurements. By simulating aerosol attenuated backscatter, we use CALIPSO measurements to evaluate the vertical structure of our aerosol estimates, in particular in regions where we have larger discrepancies with OMI. Finally, the consistency of our AOD estimates with estimates from MISR, MODIS/Deep Blue, OMI and PARASOL will be briefly discussed.

  5. An Overview of the GEOS-5 Aerosol Reanalysis

    NASA Technical Reports Server (NTRS)

    da Silva, Arlindo; Colarco, Peter Richard; Damenov, Anton Spasov; Buchard-Marchant, Virginie; Randles, Cynthia A.; Gupta, Pawan

    2011-01-01

    absorption on a global scale, we perform a detailed radiative transfer calculation to simulate the UV aerosol index, comparing our results to OMI measurements. By simulating aerosol attenuated backscatter, we use CALIPSO measurements to evaluate the vertical structure of our aerosol estimates, in particular in regions where we have larger discrepancies with OMI. Finally, the consistency of our AOD estimates with estimates from MISR, MODIS/Deep Blue, OMI and PARASOL will be briefly discussed.

  6. CALIPSO Observations of Aerosol Properties Near Clouds

    NASA Technical Reports Server (NTRS)

    Marshak, Alexander; Varnai, Tamas; Yang, Weidong

    2010-01-01

    Clouds are surrounded by a transition zone of rapidly changing aerosol properties. Characterizing this zone is important for better understanding aerosol-cloud interactions and aerosol radiative effects as well as for improving satellite measurements of aerosol properties. We present a statistical analysis of a global dataset of CALIPSO (Cloud-Aerosol Lidar and infrared Pathfinder Satellite Observation) Lidar observations over oceans. The results show that the transition zone extends as far as 15 km away from clouds and it is ubiquitous over all oceans. The use of only high confidence level cloud-aerosol discrimination (CAD) data confirms the findings. However, the results underline the need for caution to avoid biases in studies of satellite aerosol products, aerosol-cloud interactions, and aerosol direct radiative effects.

  7. Satellite Remote Sensing: Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.

    2013-01-01

    Aerosols are solid or liquid particles suspended in the air, and those observed by satellite remote sensing are typically between about 0.05 and 10 microns in size. (Note that in traditional aerosol science, the term "aerosol" refers to both the particles and the medium in which they reside, whereas for remote sensing, the term commonly refers to the particles only. In this article, we adopt the remote-sensing definition.) They originate from a great diversity of sources, such as wildfires, volcanoes, soils and desert sands, breaking waves, natural biological activity, agricultural burning, cement production, and fossil fuel combustion. They typically remain in the atmosphere from several days to a week or more, and some travel great distances before returning to Earth's surface via gravitational settling or washout by precipitation. Many aerosol sources exhibit strong seasonal variability, and most experience inter-annual fluctuations. As such, the frequent, global coverage that space-based aerosol remote-sensing instruments can provide is making increasingly important contributions to regional and larger-scale aerosol studies.

  8. Climate forcing by anthropogenic aerosols

    NASA Technical Reports Server (NTRS)

    Charlson, R. J.; Schwartz, S. E.; Hales, J. M.; Cess, R. D.; Coakley, J. A., Jr.; Hansen, J. E.; Hofmann, D. J.

    1992-01-01

    Although long considered to be of marginal importance to global climate change, tropospheric aerosol contributes substantially to radiative forcing, and anthropogenic sulfate aerosol, in particular, has imposed a major perturbation to this forcing. Both the direct scattering of short-wavelength solar radiation and the modification of the shortwave reflective properties of clouds by sulfate aerosol particles increase planetary albedo, thereby exerting a cooling influence on the planet. Current climate forcing due to anthropogenic sulfate is estimated to be -1 to -2 watts per square meter, globally averaged. This perturbation is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign. Thus, the aerosol forcing has likely offset global greenhouse warming to a substantial degree. However, differences in geographical and seasonal distributions of these forcings preclude any simple compensation. Aerosol effects must be taken into account in evaluating anthropogenic influences on past, current, and projected future climate and in formulating policy regarding controls on emission of greenhouse gases and sulfur dioxide. Resolution of such policy issues requires integrated research on the magnitude and geographical distribution of aerosol climate forcing and on the controlling chemical and physical processes.

  9. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    1999-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  10. Nucleic acid indexing

    DOEpatents

    Guilfoyle, Richard A.; Guo, Zhen

    2001-01-01

    A restriction site indexing method for selectively amplifying any fragment generated by a Class II restriction enzyme includes adaptors specific to fragment ends containing adaptor indexing sequences complementary to fragment indexing sequences near the termini of fragments generated by Class II enzyme cleavage. A method for combinatorial indexing facilitates amplification of restriction fragments whose sequence is not known.

  11. Enhancement of aerosol characterization using synergy of lidar and sun - photometer coincident observations: the GARRLiC algorithm

    NASA Astrophysics Data System (ADS)

    Lopatin, A.; Dubovik, O.; Chaikovsky, A.; Goloub, Ph.; Lapyonok, T.; Tanré, D.; Litvinov, P.

    2013-03-01

    Currently most of experiments pursuing comprehensive characterization of atmosphere include coordinated observations by both lidar and radiometers in order to obtain important complimentary information about aerosol properties. The passive observations by radiometers from ground are mostly sensitive to the properties of aerosol in total atmospheric column and have very limited sensitivity to vertical structure of the atmosphere. Such observations are commonly used for measuring aerosol optical thickness and deriving the information about aerosol microphysics including aerosol particles shape, size distribution, and complex refractive index. In a contrast, lidar observations of atmospheric responses from different altitudes to laser pulses emitted from ground are designed to provide accurate profiling of the atmospheric properties. The interpretation of the lidar observation generally relies on some assumptions about aerosol type and loading. Here we present the GARRLiC algorithm (Generalized Aerosol Retrieval from Radiometer and Lidar Combined data) that simultaneously inverts co-incident lidar and radiometer observations and derives a united set of aerosol parameters. Such synergetic retrieval is expected to result in additional enhancements in derived aerosol properties because the backscattering observations by lidar add some sensitivity to the columnar properties of aerosol, while radiometric observations provide sufficient constraints on aerosol type and loading that generally are missing in lidar signals. GARRLiC is based on AERONET algorithm for inverting combined observations by radiometer and multi-wavelength elastic lidar observations. It is expected that spectral changes of backscattering signal obtained by multi-wavelength lidar at different altitudes provide some sensitivity to the vertical variability of aerosol particle sizes. In order to benefit from this sensitivity the algorithm is set to derive not only the vertical profile of total aerosol

  12. Application of GOES-12 Aerosol Optical Depths and OMI Aerosol Indices to Evaluate NOAA/NESDIS Hazard Mapping System Smoke Analysis

    NASA Astrophysics Data System (ADS)

    Zeng, J.; Kondragunta, S.

    2006-05-01

    NOAA/NESDIS Hazard Mapping System (HMS) provides biomass burning fires and smoke analysis products to users. The smoke analysis is done by human analysts by inspecting visible imagery and fire locations. Analysts have difficulty in drawing plumes once the plumes are removed from the source (fires) and mixed with clouds and other types of aerosols. NOAA/NESDIS also provides GOES Aerosol Optical Depth (AOD) product to the users. The AOD product is derived from visible radiance measurements using a look-up table which is created assuming a continental aerosol model. In this study we examine the usefulness of Aura Ozone Monitoring Instrument (OMI) Aerosol Index (AI) in evaluating the analyst drawn smoke plumes and GOES AODs corresponding to smoke plumes. OMI AI in the near UV and visible bands is capable of distinguishing between absorbing aerosols and non-absorbing aerosols. We will present analysis of GOES AODs, OMI AI, and HMS smoke analysis product for several prescribed and natural fires observed during 2005. This analysis is expected to provide information on average percent area overlap between GOES AOD and HMS smoke plumes, OMI AI and HMS smoke plumes, and GOES AOD and OMI AI that will lead to an assessment of HMS smoke analysis.

  13. 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.

  14. Test-Aerosol Generator For Calibrating Particle Counters

    NASA Technical Reports Server (NTRS)

    Mogan, Paul A.; Adams, Alois J.; Schwindt, Christian J.; Hodge, Timothy R.; Mallow, Tim J.; Duong, Anh A.; Bukauskas, Vyto V.

    1996-01-01

    Apparatus generates clean, stable aerosol stream for use in testing and calibrating laser-based aerosol-particle counter. Size and concentration of aerosol particles controlled to ensure accurate calibration. Cheap, widely available medical nebulizers used to generate aerosols.

  15. Optical properties of mineral dust aerosol in the thermal infrared

    NASA Astrophysics Data System (ADS)

    Köhler, Claas H.

    2017-02-01

    The optical properties of mineral dust and biomass burning aerosol in the thermal infrared (TIR) are examined by means of Fourier Transform Infrared Spectrometer (FTIR) measurements and radiative transfer (RT) simulations. The measurements were conducted within the scope of the Saharan Mineral Dust Experiment 2 (SAMUM-2) at Praia (Cape Verde) in January and February 2008. The aerosol radiative effect in the TIR atmospheric window region 800-1200 cm-1 (8-12 µm) is discussed in two case studies. The first case study employs a combination of IASI measurements and RT simulations to investigate a lofted optically thin biomass burning layer with emphasis on its potential influence on sea surface temperature (SST) retrieval. The second case study uses ground based measurements to establish the importance of particle shape and refractive index for benchmark RT simulations of dust optical properties in the TIR domain. Our research confirms earlier studies suggesting that spheroidal model particles lead to a significantly improved agreement between RT simulations and measurements compared to spheres. However, room for improvement remains, as the uncertainty originating from the refractive index data for many aerosol constituents prohibits more conclusive results.

  16. Organic nitrogen in rain and aerosol in the eastern Mediterranean atmosphere: An association with atmospheric dust

    NASA Astrophysics Data System (ADS)

    Mace, Kimberly A.; Kubilay, Nilgün; Duce, Robert A.

    2003-05-01

    From March through early May of 2000, rain and bulk aerosol samples were collected at a coastal site on the eastern Mediterranean Sea at Erdemli, Turkey, and analyzed for nitrogen (N) species, including nitrate (NO3-), nitrite (NO2-), ammonium (NH4+), water-soluble organic N, urea, and dissolved free amino acids. Other ions were also analyzed, including Ca2+, Mg2+, K+, Na+, Cl-, and SO42-. Water-soluble organic N was found to contribute ˜17% and ˜26% of the total water-soluble N in rain and aerosols, respectively. Organic N concentrations within rain and aerosols exhibited statistically significant linear relationships to Ca2+ ion (Rsqr ˜ 0.75, P < 0.05), suggesting a relationship to calcite (CaCO3) in atmospheric dust. Kinematic trajectory analyses indicated the origin of winds from arid regions, mainly in northern Africa, in 70% of the aerosols sampled. Earth Probe/Total Ozone Mapping Spectrometer aerosol index data also confirmed the influence of atmospheric dust in the region on days when Ca2+ concentrations were elevated, and trajectory analyses suggested northern Africa as a source region. The combined ion, trajectory, and aerosol index data suggest that organic N is associated with atmospheric dust in this region. Urea N and amino N represented a small percentage of the organic N fraction. In rain and aerosols, urea represented ˜11% and <1%, respectively, of the total organic N. While amino N contributed minimally to organic N totals (˜1% of total organic N in aerosols), the individual amino acids contributing ˜75% of amino N were indicative of biological organisms. Further research is needed to decipher the influence from biology and gas phase adsorption of anthropogenically derived water-soluble organics on organic N totals.

  17. Aerosol size distribution and aerosol water content measurements during Atlantic Stratocumulus Transition Experiment/Marine Aerosol and Gas Exchange

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Sievering, H.; Boatman, J.; Wellman, D.; Pszenny, A.

    1995-11-01

    Aerosol size distribution data measured during the June 1992 Marine Aerosol and Gas Exchange experiment are analyzed to investigate the characteristics of fine marine aerosol particles measured over the North Atlantic near the Azores Islands. Measured aerosol size distribution data were corrected using the corrected size calibration data based on the optical properties of particles being measured. The corrected size distribution data were then approximated with either one or two lognormal size distributions, depending on air mass conditions. Under clean air mass conditions <3 μm diameter aerosol size distributions typically exhibited two modes, consisting of an accumulation mode and the small end of the sea-salt particle mode. However, under the influence of continental polluted air masses, the aerosol size distribution was dominated by <1 μm diameter particles in a single mode with an increased aerosol concentration. Aerosol water content of accumulation mode marine aerosols was estimated from differences between several series of ambient and dried aerosol size distributions. The average aerosol water fraction was 0.31, which is in good agreement with an empirical aerosol growth model estimate. The average rate of SO4= production in the accumulation mode aerosol water by H2O2 oxidation was estimated to be <7×10-10 mol L-1 s-1, which is an insignificant contributor to the observed non-sea-salt SO4= in the accumulation mode.

  18. Automating Index Preparation

    DTIC Science & Technology

    1987-03-23

    Automating Index Preparation* Pehong Chent Michael A. Harrison Computer Science Division University of CaliforniaI Berkeley, CA 94720 March 23, 1987...Abstract Index preparation is a tedious and time-consuming task. In this paper we indicate * how the indexing process can be automated in a way which...identified and analyzed. Specifically, we describe a framework for placing index commands in the document and a general purpose index processor which

  19. Satellite Retrieval of Aerosol Properties

    NASA Astrophysics Data System (ADS)

    de Leeuw, G.; Robles Gonzalez, C.; Kusmierczyk-Michulec, J.; Decae, R.

    SATELLITE RETRIEVAL of AEROSOL PROPERTIES G. de Leeuw, C. Robles Gonzalez, J. Kusmierczyk-Michulec and R. Decae TNO Physics and Electronics Laboratory, The Hague, The Netherlands; deleeuw@fel.tno.nl Methods to retrieve aerosol properties over land and over sea were explored. The dual view offered by the ATSR-2 aboard ERS-2 was used by Veefkind et al., 1998. The retrieved AOD (aerosol optical depth) values compare favourably with collocated sun photometer measurements, with an accuracy of 0.06 +/- 0.05 in AOD. An algorithm developed for GOME on ERS-2 takes advantage of the low surface reflection in the UV (Veefkind et al., 2000). AOD values retrieved from ATSR-2 and GOME data over western Europe are consistent. The results were used to produce a map of mean AOD values over Europe for one month (Robles-Gonzalez et al., 2000). The ATSR-2 is al- gorithm is now extended with other aerosol types with the aim to apply it over the In- dian Ocean. A new algorithm is being developed for the Ozone Monitoring Instrument (OMI) to be launched in 2003 on the NASA EOS-AURA satellite. It is expected that, based on the different scattering and absorption properties of various aerosol types, five major aerosol classes can be distinguished. The experience with the retrieval of aerosol properties by using several wavelength bands is used to develop an algorithm for Sciamachy to retrieve aerosol properties both over land and over the ocean which takes advantage of the wavelengths from the UV to the IR. The variation of the AOD with wavelength is described by the Angstrom parameter. The AOD and the Angstrom parameter together yield information on the aerosol size distribution, integrated over the column. Analysis of sunphotometer data indicates a relation between the Angstrom parameter and the mass ratio of certain aerosols (black carbon, organic carbon and sea salt) to the total particulate matter. This relation has been further explored and was applied to satellite data over land to

  20. Subarctic atmospheric aerosol composition: 1. Ambient aerosol characterization

    SciTech Connect

    Friedman, Beth; Herich, Hanna; Kammermann, Lukas; Gross, Deborah S.; Ameth, Almut; Holst, Thomas; Lohmann, U.; Cziczo, Daniel J.

    2009-07-10

    Sub-Arctic aerosol was sampled during July 2007 at the Abisko Research Station Stordalen field site operated by the Royal Swedish Academy of Sciences. Located in northern Sweden at 68º latitude and 385 meters above sea level (msl), this site is classified as a semi-continuous permafrost mire. Number density, size distribution, cloud condensation nucleus properties, and chemical composition of the ambient aerosol were determined. Backtrajectories showed that three distinct airmasses were present over Stordalen during the sampling period. Aerosol properties changed and correlated with airmass origin to the south, northeast, or west. We observe that Arctic aerosol is not compositionally unlike that found in the free troposphere at mid-latitudes. Internal mixtures of sulfates and organics, many on insoluble biomass burning and/or elemental carbon cores, dominate the number density of particles from ~200 to 2000 nm aerodynamic diameter. Mineral dust which had taken up gas phase species was observed in all airmasses. Sea salt, and the extent to which it had lost volatile components, was the aerosol type that most varied with airmass.

  1. Aerosol retrievals from AVHRR radiances: effects of particle nonsphericity and absorption and an updated long-term global climatology of aerosol properties

    NASA Astrophysics Data System (ADS)

    Mishchenko, M.; Geogdzhaev, I.; Liu, L.; Orgen, A.; Lacis, A.; Rossow, W.; Hovenier, J.; Volten, H.; Muñoz, O.

    2003-09-01

    The paper describes and discusses long-term global retrievals of aerosol properties from channel-1 and -2 Advanced Very High Resolution Radiometer (AVHRR) radiances. We reconfirm the previously reached conclusion that the nonsphericity of dust-like and dry sea salt aerosols can lead to very large errors in the retrieved optical thickness if one mistakenly applies the scattering model for spherical particles. Comparisons of single-scattering albedo and Ångström exponent values retrieved from the AVHRR data and those measured in situ at Sable Island indicate that the currently adopted value 0.003 can be a reasonable choice for the imaginary part of the aerosol refractive index in the global satellite retrievals. Several unexpected features in the long-term satellite record indicate a serious problem with post-launch calibration of channel-2 radiances from the NOAA-11 spacecraft. We solve this problem by using a simple re-calibration procedure removing the observed artifacts and derive a global climatology of aerosol optical thickness and size over the oceans for the period extending from July 1983 to December 1999. The global monthly mean optical thickness and Ångström exponent of tropospheric aerosols show no significant trends over the entire period and oscillate around the average values 0.145 and 0.75, respectively. The Northern hemisphere means optical thickness systematically exceeds that averaged over the Southern hemisphere. The AVHRR retrieval results during the period affected by the Mt. Pinatubo eruption are consistent with the retrievals of the stratospheric aerosol optical thickness based on Stratospheric Aerosol and Gas Experiment (SAGE) data. Time series of the aerosol optical thickness and Ângström exponent derived for four separate geographic regions exhibit varying degrees of seasonal variability controlled by local meteorological events and/or anthropogenic activities.

  2. 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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  4. Amplification of ENSO effects on Indian summer monsoon by absorbing aerosols

    NASA Astrophysics Data System (ADS)

    Kim, Maeng-Ki; Lau, William K. M.; Kim, Kyu-Myong; Sang, Jeong; Kim, Yeon-Hee; Lee, Woo-Seop

    2016-04-01

    In this study, we present observational evidence, based on satellite aerosol measurements and MERRA reanalysis data for the period 1979-2011, indicating that absorbing aerosols can have strong influence on seasonal-to-interannual variability of the Indian summer monsoon rainfall, including amplification of ENSO effects. We find a significant correlation between ENSO (El Nino Southern Oscillation) and aerosol loading in April-May, with La Nina (El Nino) conditions favoring increased (decreased) aerosol accumulation over northern India, with maximum aerosol optical depth over the Arabian Sea and Northwestern India, indicative of strong concentration of dust aerosols transported from West Asia and Middle East deserts. Composite analyses based on a normalized aerosol index (NAI) show that high concentration of aerosol over northern India in April-May is associated with increased moisture transport, enhanced dynamically induced warming of the upper troposphere over the Tibetan Plateau, and enhanced rainfall over northern India and the Himalayan foothills during May-June, followed by a subsequent suppressed monsoon rainfall over all India, consistent with the elevated heat pump (EHP) hypothesis (Lau et al. in Clim Dyn 26:855-864, 2006. doi: 10.1007/s00382-006-0114-z). Further analyses from sub-sampling of ENSO years, with normal (<1-σ), and abnormal (>1-σ) NAI over northern India respectively show that the EHP may lead to an amplification of the Indian summer monsoon response to ENSO forcing, particularly with respect to the increased rainfall over the Himalayan foothills, and the warming of the upper troposphere over the Tibetan Plateau. Our results suggest that absorbing aerosol, particular desert dusts can strongly modulate ENSO influence, and possibly play important roles as a feedback agent in climate change in Asian monsoon regions.

  5. Aerosolized liposome-based delivery of amphotericin B to alveolar macrophages.

    PubMed

    Vyas, Suresh P; Quraishi, Shama; Gupta, Swati; Jaganathan, K S

    2005-05-30

    The present study was aimed at preparation, characterization, and performance evaluation of amphotericin B (Amp B)-loaded aerosolized liposomes for their selective presentation to lungs (alveolar macrophages), that being the densest site of Aspergillosis infection. Egg phosphatidylcholine (PC)- and cholesterol (Chol)-based liposomes were modified by coating them with alveolar macrophage-specific ligands (O-palmitoyl mannan, OPM, and O-polmitoyl pullulan, OPP). The prepared formulations were characterized in vitro for vesicle morphology, mean vesicle size, vesicle size distribution and percent drug entrapment. Pressurized packed systems based on preformed liposomal formulations in chlorofluorocarbon aerosol propellants were prepared. In vitro airways penetration efficiency of the liposomal aerosols was determined by percent dose reaching the peripheral airways, it was recorded 1.4-1.6 times lower as compared to plain drug solution-based aerosol. In vivo tissue distribution studies on albino rats suggested the preferential accumulation of OPM- and OPP-coated formulations in the lung macrophages. Higher lung drug concentration was recorded in case of ligand-anchored liposomal aerosols as compared to plain drug solution and plain liposome-based aerosols. The drug was estimated in the lung in high concentration even after 24 h. The drug-localization index calculated after 6 h was nearly 1.42-, 4.47-, and 4.16-fold, respectively, for plain, OPM-, and OPP-coated liposomal aerosols as compared to plain drug solution-based aerosols. These results suggest that the ligand anchored liposomal aerosols are not only effective in rapid attainment of high-drug concentration in lungs with high population of alveolar macrophages but also maintain the same over prolonged period of time. The significance of targeting potential of the developed systems was established.

  6. Sensitivity of PARASOL multi-angle photo-polarimetric aerosol retrievals to cloud contamination

    NASA Astrophysics Data System (ADS)

    Stap, F. A.; Hasekamp, O.; Röckmann, T.

    2014-10-01

    An important problem in satellite remote sensing of aerosols is related to the need to perform an adequate cloud screening. If a cloud screening is applied that is not strict enough, the ground scene has the probability of residual cloud cover which causes large errors on the retrieved aerosol parameters. On the other hand, if the cloud screening procedure is too strict, too many clear sky cases, especially near-cloud scenes, will falsely be flagged cloudy. The detrimental effects of cloud contamination as well as the importance of aerosol cloud interactions that can be studied in these near-cloud scenes call for new approaches to cloud screening. Multi-angle, multi-wavelength photo-polarimetric measurements have a unique capability to distinguish between scattering by (liquid) cloud droplets and aerosol particles. In this paper the sensitivity of aerosol retrievals from multi-angle, photo-polarimetric measurements to cloud contamination is investigated and the ability to intrinsically filter the cloud contaminated scenes based on a goodness-of-fit criteria is evaluated. Hereto, an aerosol retrieval algorithm is applied to a partially clouded, synthetic data-set including partial cloud cover as well as non-cloud screened POLDER-3/PARASOL observations It is found that a goodness-of-fit filter, together with a filter on the coarse mode refractive index (mrcoarse > 1.335) and a cirrus screening adequately reject the cloud contaminated scenes. No bias nor larger SD are found in the retrieved parameters for this intrinsic cloud filter compared to the parameters retrieved in a priori cloud screened data-set (using MODIS/AQUA cloud masks) of PARASOL observations. Moreover, less high aerosol load scenes are misinterpreted as cloud contaminated. The retrieved aerosol optical thickness, single scattering albedo and Ångström exponent show good agreement with AERONET observations. Furthermore, the synthetic retrievals give confidence in the ability of the algorithm to

  7. Sensitivity of PARASOL multi-angle photopolarimetric aerosol retrievals to cloud contamination

    NASA Astrophysics Data System (ADS)

    Stap, F. A.; Hasekamp, O. P.; Röckmann, T.

    2015-03-01

    An important problem in satellite remote sensing of aerosols is related to the need to perform an adequate cloud screening. If a cloud screening is applied that is not strict enough, the ground scene has the probability of residual cloud cover which causes large errors on the retrieved aerosol parameters. On the other hand, if the cloud-screening procedure is too strict, too many clear sky cases, especially near-cloud scenes, will falsely be flagged cloudy. The detrimental effects of cloud contamination as well as the importance of aerosol cloud interactions that can be studied in these near-cloud scenes call for new approaches to cloud screening. Multi-angle multi-wavelength photopolarimetric measurements have a unique capability to distinguish between scattering by (liquid) cloud droplets and aerosol particles. In this paper the sensitivity of aerosol retrievals from multi-angle photopolarimetric measurements to cloud contamination is investigated and the ability to intrinsically filter the cloud-contaminated scenes based on a goodness-of-fit criteria is evaluated. Hereto, an aerosol retrieval algorithm is applied to a partially clouded over-ocean synthetic data set as well as non-cloud-screened over-ocean POLDER-3/PARASOL observations. It is found that a goodness-of-fit filter, together with a filter on the coarse mode refractive index (mrcoarse > 1.335) and a cirrus screening, adequately rejects the cloud-contaminated scenes. No bias or larger SD are found in the retrieved parameters for this intrinsic cloud filter compared to the parameters retrieved in a priori cloud-screened data set (using MODIS/AQUA cloud masks) of PARASOL observations. Moreover, less high-aerosol load scenes are misinterpreted as cloud contaminated. The retrieved aerosol optical thickness, single scattering albedo and Ångström exponent show good agreement with AERONET observations. Furthermore, the synthetic retrievals give confidence in the ability of the algorithm to correctly

  8. Absorbing aerosols at high relative humidity: linking hygroscopic growth to optical properties

    NASA Astrophysics Data System (ADS)

    Flores, J. Michel; Bar-Or, R. Z.; Bluvshtein, N.; Abo-Riziq, A.; Kostinski, A.; Borrmann, S.; Koren, I.; Koren, I.; Rudich, Y.

    2012-06-01

    One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. Aerosols exposed to high humidity will change their chemical, physical, and optical properties due to their increased water content. To model hydrated aerosols, atmospheric chemistry and climate models often use the volume weighted mixing rule to predict the complex refractive index (RI) of aerosols when they interact with high relative humidity, and, in general, assume homogeneous mixing. This study explores the validity of these assumptions. A humidified cavity ring down aerosol spectrometer (CRD-AS) and a tandem hygroscopic DMA (differential mobility analyzer) are used to measure the extinction coefficient and hygroscopic growth factors of humidified aerosols, respectively. The measurements are performed at 80% and 90%RH at wavelengths of 532 nm and 355 nm using size-selected aerosols with different degrees of absorption; from purely scattering to highly absorbing particles. The ratio of the humidified to the dry extinction coefficients (fRHext(%RH, Dry)) is measured and compared to theoretical calculations based on Mie theory. Using the measured hygroscopic growth factors and assuming homogeneous mixing, the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements. We found a weak linear dependence or no dependence of fRH(%RH, Dry) with size for hydrated absorbing aerosols in contrast to the non-monotonically decreasing behavior with size for purely scattering aerosols. No discernible difference could be made between the two wavelengths used. Less than 7% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference. However, for substances with growth factor less than 1.15 the volume weighted mixing rule assumption

  9. YAG aerosol lidar

    NASA Technical Reports Server (NTRS)

    Sullivan, R.

    1988-01-01

    The Global Atmospheric Backscatter Experiment (GLOBE) Mission, using the NASA DC-8 aircraft platform, is designed to provide the magnitude and statistical distribution of atmospheric backscatter cross section at lidar operating wavelengths. This is a fundamental parameter required for the Doppler lidar proposed to be used on a spacecraft platform for global wind field measurements. The prime measurements will be made by a CO2 lidar instrument in the 9 to 10 micron range. These measurements will be complemented with the Goddard YAG Aerosol Lidar (YAL) data in two wavelengths, 0.532 and 1.06 micron, in the visible and near-infrared. The YAL, is being designed to utilize as much existing hardware, as feasible, to minimize cost and reduce implementation time. The laser, energy monitor, telescope and detector package will be mounted on an optical breadboard. The optical breadboard is mounted through isolation mounts between two low boy racks. The detector package will utilize a photomultiplier tube for the 0.532 micron channel and a silicon avalanche photo detector (APD) for the 1.06 micron channel.

  10. Investigation Of Trace Gas To Aerosol Relationships Over BioMass Burning Areas Using Daily Satellite Observations

    NASA Astrophysics Data System (ADS)

    Wagner, Thomas; Penning de Vries, Marloes; Beirle, Steffen; Zorner, Jan

    2013-12-01

    We investigate the spatial and temporal relationships between satellite observations of selected trace gases (CO, NO2, HCHO, CHOCHO), the UV aerosol index (UVAI) and the aerosol optical depth (AOD) measured either by satellite or from ground. In contrast to previous studies we use daily observations, since only from daily observations information on individual biomass burning events can be obtained. Unlike the AOD, satellite observations of trace gases and UVAI are possible in the presence of clouds. This might be important for the study of aerosol-cloud-interactions.

  11. Selected translated abstracts of Russian-language climate-change publications, III aerosols: Issue 164

    SciTech Connect

    Razuvaev, V.N.; Ssivachok, S.G.

    1995-10-01

    This report presents abstracts in Russian and translated into English of important Russian-language literature concerning aerosols as they relate to climate change. In addition to the bibliographic citations and abstracts translated into English, this report presents the original citations and abstracts in Russian. Author and title indexes are included to assist the reader in locating abstracts of particular interest.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  13. Application of Satellite and Ground-based Data to Investigate the UV Radiative Effects of Australian Aerosols

    NASA Technical Reports Server (NTRS)

    Kalashnikova, Olga V.; Mills, Franklin P.; Eldering, Annmarie; Anderson, Don

    2007-01-01

    An understanding of the effect of aerosols on biologically- and photochemically-active UV radiation reaching the Earth's surface is important for many ongoing climate, biophysical, and air pollution studies. In particular, estimates of the UV characteristics of the most common Australian aerosols will be valuable inputs to UV Index forecasts, air quality studies, and assessments of the impact of regional environmental changes. By analyzing climatological distributions of Australian aerosols we have identified sites where co-located ground-based UV-B and ozone measurements were available during episodes of relatively high aerosol activity. Since at least June 2003, surface UV global irradiance spectra (285-450 nm) have been measured routinely at Darwin and Alice Springs in Australia by the Australian Bureau of Meteorology (BoM). Using colocated sunphotometer measurements at Darwin and Alice Springs, we identified several episodes of relatively high aerosol activity. Aerosol air mass types were analyzed from sunphotometer-derived angstrom parameter, MODIS fire maps and MISR aerosol property retrievals. To assess aerosol effects we compared the measured UV irradiances for aerosol-loaded and clear-sky conditions with each other and with irradiances simulated using the libRadtran radiative transfer model for aerosol-free conditions. We found that for otherwise similar atmospheric conditions, smoke aerosols over Darwin reduced the surface UV irradiance by as much as 40-50% at 290-300 nm and 20-25% at 320-400 nm near active fires (aerosol optical depth, AOD, at 500 nm approximately equal to 0.6). Downwind of fires, the smoke aerosols over Darwin reduced the surface irradiance by 15-25% at 290-300 nm and approximately 10% at 320-350 nm (AOD at 500 nm approximately equal to 0.2). The effect of smoke increased with decrease of wavel strongest in the UV-B. The aerosol attenuation factors calculated for the selected cases suggest smoke over Darwin has an effect on surface 340

  14. Aerosol Properties Changes of Northeast Asia due to a Severe Dust Storm in April 2014

    NASA Astrophysics Data System (ADS)

    Fang, Li; Wang, Shupeng; Yu, Tao; Gu, Xingfa; Zhang, Xingying; Wang, Weihe; Ren, Suling

    2016-04-01

    This study focuses on analyzing the aerosol properties changes due to the dust storm named as "China's Great Wall of Dust" oriented from Taklimakan desert in April, 2014. Dust identification IDDI (Infrared Difference Dust Index) images from FY-2E and true color composite images from FY-3C MERSI (Medium Resolution Spectral Imager) show the breakout and transport of the dust storm.From 4-day forward air mass trajectories, the dusty air masses were mostly transported within the lower boundary layer(<3km) over the Northwest China on April 23rd and April 24th, however they were progressively increasing in altitude to above 5km above the surface when they reached the central part of north China region (32°N-42°N; 105°E-123°E). 3-hourly data records at surface stations suggest that anticyclonic circulation occupying southern Xinjiang basin and cyclonic circulation maintaining in Mongolia formed the typical Synoptic condition which leaded to the strong dust storm. Aerosol Index (AI) results of TOU (Total Ozone Unit) aboard FY-3B are first developed and used in studying the affected areas due to the dust storm. The retrieved aerosol indexes show sensitivity to the dust particles. The dust affected areas agree with the synoptic meteorological condition analysis, which prove the synoptic meteorological condition is the main reason for the break out and transport of the dust storm. Anomalies of the average MODIS (Moderate Resolution Imaging Spectroradiometer) AOD (Aerosol Optical Depth) distributions over Northeast Asia during the dust storm to the average of that in April between 2010-2014 show high aerosol loading due to the dust storm. Compared with the 5-year average AOD in April, aerosol loading during this dust storm was much higher, with AOD values at 550nm up to 2.9 observed over the northwest China.The dust storm also brought different change in the aerosol microphysical properties between Beijing and Dalanzadgad. Aerosol Robotic Network (AERONET) retrievals

  15. CENDI Indexing Workshop

    NASA Technical Reports Server (NTRS)

    1994-01-01

    The CENDI Indexing Workshop held at NASA Headquarters, Two Independence Square, 300 E Street, Washington, DC, on September 21-22, 1994 focused on the following topics: machine aided indexing, indexing quality, an indexing pilot project, the MedIndEx Prototype, Department of Energy/Office of Scientific and Technical Information indexing activities, high-tech coding structures, category indexing schemes, and the Government Information Locator Service. This publication consists mostly of viewgraphs related to the above noted topics. In an appendix is a description of the Government Information Locator Service.

  16. Factors Affecting Aerosol Radiative Forcing

    NASA Astrophysics Data System (ADS)

    Wang, Jingxu; Lin, Jintai; Ni, Ruijing

    2016-04-01

    Rapid industrial and economic growth has meant a large amount of aerosols in the atmosphere with strong radiative forcing (RF) upon the climate system. Over parts of the globe, the negative forcing of aerosols has overcompensated for the positive forcing of greenhouse gases. Aerosol RF is determined by emissions and various chemical-transport-radiative processes in the atmosphere, a multi-factor problem whose individual contributors have not been well quantified. In this study, we analyze the major factors affecting RF of secondary inorganic aerosols (SIOAs, including sulfate, nitrate and ammonium), primary organic aerosol (POA), and black carbon (BC). We analyze the RF of aerosols produced by 11 major regions across the globe, including but not limited to East Asia, Southeast Asia, South Asia, North America, and Western Europe. Factors analyzed include population size, per capita gross domestic production (GDP), emission intensity (i.e., emissions per unit GDP), chemical efficiency (i.e., mass per unit emissions) and radiative efficiency (i.e., RF per unit mass). We find that among the 11 regions, East Asia produces the largest emissions and aerosol RF, due to relatively high emission intensity and a tremendous population size. South Asia produce the second largest RF of SIOA and BC and the highest RF of POA, in part due to its highest chemical efficiency among all regions. Although Southeast Asia also has large emissions, its aerosol RF is alleviated by its lowest chemical efficiency. The chemical efficiency and radiative efficiency of BC produced by the Middle East-North Africa are the highest across the regions, whereas its RF is lowered by a small per capita GDP. Both North America and Western Europe have low emission intensity, compensating for the effects on RF of large population sizes and per capita GDP. There has been a momentum to transfer industries to Southeast Asia and South Asia, and such transition is expected to continue in the coming years. The

  17. The Effect of Aerosol Hygroscopicity and Volatility on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

    2014-12-01

    Secondary organic aerosol (SOA) from biogenic sources can influence optical properties of ambient aerosol by altering its hygroscopicity and contributing to light absorption directly via formation of brown carbon and indirectly by enhancing light absorption by black carbon ("lensing effect"). The magnitude of these effects remains highly uncertain. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of relative humidity and temperature on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). The sample-conditioning system provided measurements at ambient RH, 10%RH ("dry"), 85%RH ("wet"), and 200 C ("TD"). In parallel to these measurements, a long residence time temperature-stepping thermodenuder (TD) and a variable residence time constant temperature TD in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. We will present results of the on-going analysis of the collected data set. We will show that both temperature and relative humidity have a strong effect on aerosol optical properties. SOA appears to increase aerosol light absorption by about 10%. TD measurements suggest that aerosol equilibrated fairly quickly, within 2 s. Evaporation varied substantially with ambient aerosol loading and composition and meteorology.

  18. CATS Aerosol Typing and Future Directions

    NASA Technical Reports Server (NTRS)

    McGill, Matt; Yorks, John; Scott, Stan; Palm, Stephen; Hlavka, Dennis; Hart, William; Nowottnick, Ed; Selmer, Patrick; Kupchock, Andrew; Midzak, Natalie; Trepte, Chip; Vaughan, Mark; Colarco, Peter; da Silva, Arlindo

    2016-01-01

    The Cloud Aerosol Transport System (CATS), launched in January of 2015, is a lidar remote sensing instrument that will provide range-resolved profile measurements of atmospheric aerosols and clouds from the International Space Station (ISS). CATS is intended to operate on-orbit for at least six months, and up to three years. Status of CATS Level 2 and Plans for the Future:Version. 1. Aerosol Typing (ongoing): Mode 1: L1B data released later this summer; L2 data released shortly after; Identify algorithm biases (ex. striping, FOV (field of view) biases). Mode 2: Processed Released Currently working on correcting algorithm issues. Version 2 Aerosol Typing (Fall, 2016): Implementation of version 1 modifications Integrate GEOS-5 aerosols for typing guidance for non spherical aerosols. Version 3 Aerosol Typing (2017): Implementation of 1-D Var Assimilation into GEOS-5 Dynamic lidar ratio that will evolve in conjunction with simulated aerosol mixtures.

  19. Aerosol Emission during Human Speech

    NASA Astrophysics Data System (ADS)

    Asadi, Sima; Ristenpart, William

    2016-11-01

    The traditional emphasis for airborne disease transmission has been on coughing and sneezing, which are dramatic expiratory events that yield easily visible droplets. Recent research suggests that normal speech can release even larger quantities of aerosols that are too small to see with the naked eye, but are nonetheless large enough to carry a variety of pathogens (e.g., influenza A). This observation raises an important question: what types of speech emit the most aerosols? Here we show that the concentration of aerosols emitted during healthy human speech is positively correlated with both the amplitude (loudness) and fundamental frequency (pitch) of the vocalization. Experimental measurements with an aerodynamic particle sizer (APS) indicate that speaking in a loud voice (95 decibels) yields up to fifty times more aerosols than in a quiet voice (75 decibels), and that sounds associated with certain phonemes (e.g., [a] or [o]) release more aerosols than others. We interpret these results in terms of the egressive airflow rate associated with each phoneme and the corresponding fundamental frequency, which is known to vary significantly with gender and age. The results suggest that individual speech patterns could affect the probability of airborne disease transmission.

  20. Center for Aerosol Research (AEROCENTER)

    NASA Technical Reports Server (NTRS)

    Kleidman, Richard; Kaufman, Yoram; Lau, William K. M. (Technical Monitor)

    2001-01-01

    The newly established Center for Aerosol Research (AEROCENTER) located at the NASA/Goddard Space Flight Center in Greenbelt MD is dedicated to fostering interdisciplinary research in all aspects of aerosol science. AEROCENTER will be an incubator for innovative new analysis of existing data and ideas for new space missions. The plan is to tap and harvest ideas from a broad international and interdisciplinary science community and to incorporate these ideas into NASA's aerosol research effort for understanding and predicting the aerosol effect on climate and the environment. In order to achieve this goal the center aims to host several established and developing scientists for a period of 3-6 months each year. AEROCENTER will also develop a new technical infrastructure that will integrate the present aerosol research activities and data resources of GSFC/Greenbelt and GSFC/GISS, increase efficiency in the use of NASA remote sensing data, and increase the involvement of a larger national and international scientific community. The center aims to institutionalize and extend the present knowledge base within NASA into a national resource for the education and research communities.

  1. Characterisation of coated aerosols using optical tweezers and neutron reflectometry

    NASA Astrophysics Data System (ADS)

    Jones, S. H.; Ward, A.; King, M. D.

    2013-12-01

    Thin organic films are believed to form naturally on the surface of aerosols [1,2] and influence aerosol properties. Cloud condensation nuclei formation and chemical reactions such as aerosol oxidation are effected by the presence of thin films [3]. There is a requirement to characterise the physical properties of both the core aerosol and its organic film in order to fully understand the contribution of coated aerosols to the indirect effect. Two complementary techniques have been used to study the oxidation of thin organic films on the surface of aerosols; laser optical tweezers and neutron reflectometry. Micron sized polystyrene beads coated in oleic acid have been trapped in air using two counter propagating laser beams. Polystyrene beads are used as a proxy for solid aerosol. The trapped aerosol is illuminated with a white LED over a broadband wavelength range and the scattered light collected to produce a Mie spectrum [4]. Analysis of the Mie spectrum results in determination of the core polystyrene bead radius, the oleic acid film thickness and refractive index dispersion of the core and shell [5]. A flow of ozone gas can then be introduced into the aerosol environment to oxidise the thin film of oleic acid and the reaction followed by monitoring the changes in the Mie spectrum. The results demonstrate complete removal of the oleic acid film. We conclude that the use of a counter propagating optical trap combined with white light Mie spectroscopy can be used to study a range of organic films on different types of aerosols and their oxidation reactions. Neutron reflectometry has been used as a complementary technique to study the oxidation of monolayer films at the air-water interface in order to gain information on reaction kinetics. The oxidation of an oleic acid film at the air-water interface by the common tropospheric oxidant ozone has been studied using a Langmuir trough. Results indicate complete removal of the oleic acid film with ozone in agreement

  2. Coarse mode aerosol measurement using a Low Turbulence Inlet

    NASA Astrophysics Data System (ADS)

    Brooke, J.; Bart, M.; Trembath, J.; McQuaid, J. B.; Brooks, B. J.; Osborne, S.

    2012-04-01

    the LTI is a critical method of sampling quantifiably coarse mode aerosol up to 12 µm into the FAAM BAe 146 aircraft. Size distributions for the Fennec field campaign will be presented. Size distributions from the LTI are found to compare well with that of the externally mounted aircraft probes. A Compact Cascade Impactor (CCI) was incorporated along the sample line and used to collect size segregated particle samples on polyurethane foam (PUF) substrates. X-Ray Diffraction (XRD) analysis is to be used to determine mineralogy of the dust samples. From known dust mineralogy it will be possible to infer the particles optical properties, specifically refractive index. This work was supported by the Natural Environment Research Council and the Met Office. Acknowledgements include Dr J. Wilson, University of Denver, Fennec, FAAM, DLR and Avalon. Forster et al., 2007; Intergovernmental Panel on Climate Change, Cambridge University Press. Weinzierl et al. 2006; Tellus B 61, 96-117. Wendisch et al. 2004; Bulletin of the American Meteorological Society 85, 89-91. Wilson et al. 2004; Aerosol Science and Technology 38, 790-802.

  3. Retrieval of aerosol absorption properties using the AATSR satellite instrument: a case study of wildfires over Russia 2010

    NASA Astrophysics Data System (ADS)

    Rodríguez, E.; Kolmonen, P.; Virtanen, T. H.; Sogacheva, L.; Sundström, A.-M.; de Leeuw, G.

    2014-09-01

    The retrieval of aerosol properties from satellite data is based on the optimized fit of simulated and measured radiances at the top of the atmosphere (TOA). The simulations are made using a radiative transfer model with a variety of representative aerosol properties.The optimum fit is obtained for a certain combination of aerosol components, which are externally mixed to provide the aerosol model which in turn is used to calculate the aerosol optical depth (AOD). However, other aerosol properties could be provided. In the aerosol retrieval algorithm (ADV) applied to data from the Advanced Along Track Scanning Radiometer (AATSR), four aerosol components are used, each of which is defined by their (lognormal) size distribution and a complex refractive index. The fine mode fraction is a continuous mixture of weakly and strongly absorbing components which allows for the definition of any absorbing aerosol model within the specified limits. Hence, assuming that the correct aerosol model is selected during the retrieval process, also the single scattering albedo (SSA) should correctly be retrieved. In this paper we present the SSA retrieval using the ADV algorithm by application to wildfires over Russia in the summer of 2010. Together with the AOD, the SSA provides the aerosol absorbing optical depth (AAOD). The results are compared with AERONET data, i.e. AOD level 2.0 and SSA and AAOD inversion products. The RMSE is 0.03 for SSA and 0.02 for AAOD. The SSA is further evaluated by comparison with the SSA retrieved from the Ozone Monitoring Instrument (OMI). The SSA retrieved from both instruments show similar features, but the AATSR-retrieved SSA values over areas affected by wildfires are lower.

  4. Dust aerosol emission over the Sahara during summertime from Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations

    NASA Astrophysics Data System (ADS)

    Todd, Martin C.; Cavazos-Guerra, Carolina

    2016-03-01

    Dust aerosols are an important component of the climate system and a challenge to incorporate into weather and climate models. Information on the location and magnitude of dust emission remains a key information gap to inform model development. Inadequate surface observations ensure that satellite data remain the primary source of this information over extensive and remote desert regions. Here, we develop estimates of the relative magnitude of active dust emission over the Sahara desert based on data from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP). Utilising the unique vertical profile of aerosol characteristics provided by CALIOP our algorithm identifies emission from aerosol extinction and lidar backscatter in the near surface layers. From the long-term CALIOP archive of day and night-time orbits over 2006-13 we construct coarse resolution maps of a new dust emission index (DEI) for the Sahara desert during the peak summer dust season (June to September). The spatial structure of DEI indicates highest emission over a broad zone focused on the border regions of Southern Algeria, Northern Mali and northwest Niger, displaced substantially (∼7°) to the east of the mean maximum in satellite-derived aerosol optical depth. In this region night-time emission exceeds that during the day. The DEI maps substantially corroborate recently derived dust source frequency count maps based on back-tracking plumes in high temporal resolution SEVIRI imagery. As such, a convergence of evidence from multiple satellite data sources using independent methods provides an increasingly robust picture of Saharan dust emission sources. Various caveats are considered. As such, quantitative estimates of dust emission may require a synergistic combined multi-sensor analysis.

  5. Determination of the broadband optical properties of biomass burning aerosol

    NASA Astrophysics Data System (ADS)

    Bluvshtein, Nir; Flores, J. Michel; Segev, Lior; Lin, Peng; Laskin, Alexander; Rudich, Yinon

    2016-04-01

    The direct and semi-direct effects of atmospheric aerosol on the Earth's energy balance are still the two of the largest uncertainties in our understanding of anthropogenic radiative forcing. In this study we developed a new approach for determining high sensitivity broadband UV-Vis spectrum (300-650 nm) of extinction, scattering and absorption coefficients, single scattering albedo and the complex refractive index for continuous, spectral and time dependent, monitoring of polydisperse aerosols population. This new approach was applied in a study of biomass burning aerosol. Extinction, scattering and absorption coefficients (αext, αsca, αabs, respectively) were continually monitored using photoacoustic spectrometer coupled to a cavity ring down spectrometer (PA-CRD-AS) at 404 nm, a dual-channel Broadband cavity-enhanced spectrometer (BBCES) at 315-345 nm and 390-420 nm and a three channel integrating nephelometer (IN) centered at 457, 525 and 637 nm. During the biomass burning event, the measured aerosol number concentration increased by more than an order of magnitude relative to other week nights and the mode of the aerosols size distribution increased from 40-50 nm to 110nm diameter. αext and αsca increased by a factor of about 5.5 and 4.5, respectively. The αabs increased by a factor over 20, indicating a significant change in the aerosol overall chemical composition. The imaginary part of the complex RI at 404nm increased from its background level at about 0.02 to a peak of about 0.08 and the SSA decreased from 0.9 to about 0.6. Significant change of the absorption spectral dependence indicates formation of visible-light absorbing compounds. The mass absorption cross section of the water soluble organic aerosol (MACWSOA) reached up to about 12% of the corresponding value for black carbon (BC) at 450 nm and up to 30% at 300 nm. These results demonstrate the importance of biomass burning in understanding global and regional radiative forcing.

  6. Interaction of absorbing aerosols with high relative humidity

    NASA Astrophysics Data System (ADS)

    Flores, M.; Bluvshtein, N.; Abo Riziq, A.; Borrmann, S.; Rudich, Y.

    2011-12-01

    One of the major uncertainties in the understanding of Earth's climate system is the interaction between solar radiation and aerosols in the atmosphere. This interaction is dependent on the physical and chemical properties of the aerosols and on the wavelength of the incident light. Aerosols exposed to high humidity areas will change their chemical, physical, and optical properties. To model hydrated aerosols, atmospheric chemistry models use the volume weighted mixing rule to predict the complex refractive index (RI) of aerosols when they interact with high relative humidity areas, and, in general, assume homogeneous mixing. The validity of these assumptions is explored. The extinction coefficient and growth factor of humidified aerosols, at 80% and 90% RH, and at 532 nm and 355 nm wavelengths was measured for size-selected aerosols of ammonium sulfate, peat (a lightly absorbing humic-like substance proxy), nigrosine (a black dye to model highly absorbing substances), and a mixture of AS and nigrosine. The ratio of the humidified extinction coefficients to the dry (fRHext(%RH,Dry)) is explored. The measured fRHext(%RH,Dry) is compared to theoretical calculations based on Mie theory, and using the measured growth factors and assuming homogeneous mixing the expected RIs using the volume weighted mixing rule are compared to the RIs derived from the extinction measurements. Moreover, the differences between assuming a core-shell structure or a homogeneous mixing of the substances is examined. We found slightly linear to no dependency of fRH(%RH,Dry) with size for absorbing substances in contrast to the decreasing exponential behavior with size for purely scattering substances, but no discernable difference could be made between the two wavelengths used. Less than 5% differences were found between the real parts of the complex refractive indices derived and those calculated using the volume weighted mixing rule, and the imaginary parts had up to a 20% difference

  7. Measurements of Semi-volatile Aerosol and Its Effect on Aerosol Optical Properties During Southern Oxidant and Aerosol Study

    NASA Astrophysics Data System (ADS)

    Khlystov, A.; Grieshop, A. P.; Saha, P.; Subramanian, R.

    2013-12-01

    Semi-volatile compounds, including particle-bound water, comprise a large part of aerosol mass and have a significant influence on aerosol lifecycle and its optical properties. Understanding the properties of semi-volatile compounds, especially those pertaining to gas/aerosol partitioning, is of critical importance for our ability to predict concentrations and properties of ambient aerosol. A set of state-of-the-art instruments was deployed at the SEARCH site near Centerville, AL during the Southern Oxidant and Aerosol Study (SOAS) campaign in summer 2013 to measure the effect of temperature and relative humidity on aerosol size distribution, composition and optical properties. Light scattering and absorption by temperature- and humidity-conditioned aerosols was measured using three photo-acoustic extinctiometers (PAX) at three wavelengths (405 nm, 532 nm, and 870 nm). In parallel to these measurements, a long residence time temperature-stepping thermodenuder and a variable residence time constant temperature thermodenuder in combination with three SMPS systems and an Aerosol Chemical Speciation Monitor (ACSM) were used to assess aerosol volatility and kinetics of aerosol evaporation. It was found that both temperature and relative humidity have a strong effect on aerosol optical properties. The variable residence time thermodenuder data suggest that aerosol equilibrated fairly quickly, within 2 s, in contrast to other ambient observations. Preliminary analysis show that approximately 50% and 90% of total aerosol mass evaporated at temperatures of 100 C and 180C, respectively. Evaporation varied substantially with ambient aerosol loading and composition and meteorology. During course of this study, T50 (temperatures at which 50% aerosol mass evaporates) varied from 60 C to more than 120 C.

  8. ATI TDA 5A aerosol generator evaluation

    SciTech Connect

    Gilles, D.A.

    1998-07-27

    Oil based aerosol ``Smoke`` commonly used for testing the efficiency and penetration of High Efficiency Particulate Air filters (HEPA) and HEPA systems can produce flammability hazards that may not have been previously considered. A combustion incident involving an aerosol generator has caused an investigation into the hazards of the aerosol used to test HEPA systems at Hanford.

  9. Meeting Review: Airborne Aerosol Inlet Workshop

    NASA Technical Reports Server (NTRS)

    Baumgardner, Darrel; Huebert, Barry; Wilson, Chuck

    1991-01-01

    Proceedings from the Airborne Aerosol Inlet Workshop are presented. The two central topics of discussion were the role of aerosols in atmospheric processes and the difficulties in characterizing aerosols. The following topics were discussed during the working sessions: airborne observations to date; identification of inlet design issues; inlet modeling needs and directions; objectives for aircraft experiments; and future laboratory and wind tunnel studies.

  10. Chemical Properties of Combustion Aerosols: An Overview

    EPA Science Inventory

    A wide variety of pyrogenic and anthropogenic sources emit fine aerosols to the atmosphere. The physical and chemical properties of these aerosols are of interest due to their influence on climate, human health, and visibility. Aerosol chemical composition is remarkably complex. ...

  11. Satellite Multiangle Spectropolarimetric Imaging of Aerosols

    NASA Technical Reports Server (NTRS)

    Diner, David; Macenka, Steven; Scherr, Lawrence; Seshadri, Suresh; Chipman, Russell; Keller, Christoph

    2006-01-01

    A proposed remote-sensing instrument, to be carried aboard a spacecraft in orbit around the Earth, would gather data on the spatial distribution and radiative characteristics of tropospheric aerosols. These data are needed for better understanding of the natural and anthropogenic origins of aerosols, and of the effects of aerosols on climate and atmospheric chemistry.

  12. Air ions and aerosol science

    SciTech Connect

    Tammet, H.

    1996-03-01

    Collaboration between Gas Discharge and Plasma Physics, Atmospheric Electricity, and Aerosol Science is a factor of success in the research of air ions. The concept of air ion as of any carrier of electrical current through the air is inherent to Atmospheric Electricity under which a considerable statistical information about the air ion mobility spectrum is collected. A new model of air ion size-mobility correlation has been developed proceeding from Aerosol Science and joining the methods of neighboring research fields. The predicted temperature variation of the mobility disagrees with the commonly used Langevin rule for the reduction of air ion mobilities to the standard conditions. Concurrent errors are too big to be neglected in applications. The critical diameter distinguishing cluster ions and charged aerosol particles has been estimated to be 1.4{endash}1.8 nm. {copyright} {ital 1996 American Institute of Physics.}

  13. Aerosol retrieval experiments in the ESA Aerosol_cci project

    NASA Astrophysics Data System (ADS)

    Holzer-Popp, T.; de Leeuw, G.; Griesfeller, J.; Martynenko, D.; Klüser, L.; Bevan, S.; Davies, W.; Ducos, F.; Deuzé, J. L.; Graigner, R. G.; Heckel, A.; von Hoyningen-Hüne, W.; Kolmonen, P.; Litvinov, P.; North, P.; Poulsen, C. A.; Ramon, D.; Siddans, R.; Sogacheva, L.; Tanre, D.; Thomas, G. E.; Vountas, M.; Descloitres, J.; Griesfeller, J.; Kinne, S.; Schulz, M.; Pinnock, S.

    2013-08-01

    Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010-2013), algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various aerosol retrieval algorithms. In the first experiment a common set of four aerosol components was used to provide all algorithms with the same assumptions. The second experiment introduced an aerosol property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common aerosol components. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data: qualitatively by inspection of monthly mean AOD maps and quantitatively by comparing daily gridded satellite data against daily averaged AERONET sun photometer

  14. The NLM Indexing Initiative.

    PubMed

    Aronson, A R; Bodenreider, O; Chang, H F; Humphrey, S M; Mork, J G; Nelson, S J; Rindflesch, T C; Wilbur, W J

    2000-01-01

    The objective of NLM's Indexing Initiative (IND) is to investigate methods whereby automated indexing methods partially or completely substitute for current indexing practices. The project will be considered a success if methods can be designed and implemented that result in retrieval performance that is equal to or better than the retrieval performance of systems based principally on humanly assigned index terms. We describe the current state of the project and discuss our plans for the future.

  15. Gradient Index Lens Research

    DTIC Science & Technology

    1981-10-19

    Finally, an assessment of the current technologies in gradient index has been made. This includes a series of recommendations w’iich will be...17 III. Ray Tracing in Anamorphic Gradient Index Media ......... 20 IV. Fabrication of Six Gradient Index Samples ............. 27 V. Technology ...for a basic understanding of what can and cannot be done with gradient index lenses, aside from any lack of technology for making a paricular gradient

  16. Aerosol Transport Over Equatorial Africa

    NASA Technical Reports Server (NTRS)

    Gatebe, C. K.; Tyson, P. D.; Annegarn, H. J.; Kinyua, A. M.; Piketh, S.; King, M.; Helas, G.

    1999-01-01

    Long-range and inter-hemispheric transport of atmospheric aerosols over equatorial Africa has received little attention so far. Most aerosol studies in the region have focussed on emissions from rain forest and savanna (both natural and biomass burning) and were carried out in the framework of programs such as DECAFE (Dynamique et Chimie Atmospherique en Foret Equatoriale) and FOS (Fires of Savanna). Considering the importance of this topic, aerosols samples were measured in different seasons at 4420 meters on Mt Kenya and on the equator. The study is based on continuous aerosol sampling on a two stage (fine and coarse) streaker sampler and elemental analysis by Particle Induced X-ray Emission. Continuous samples were collected for two seasons coinciding with late austral winter and early austral spring of 1997 and austral summer of 1998. Source area identification is by trajectory analysis and sources types by statistical techniques. Major meridional transports of material are observed with fine-fraction silicon (31 to 68 %) in aeolian dust and anthropogenic sulfur (9 to 18 %) being the major constituents of the total aerosol loading for the two seasons. Marine aerosol chlorine (4 to 6 %), potassium (3 to 5 %) and iron (1 to 2 %) make up the important components of the total material transport over Kenya. Minimum sulfur fluxes are associated with recirculation of sulfur-free air over equatorial Africa, while maximum sulfur concentrations are observed following passage over the industrial heartland of South Africa or transport over the Zambian/Congo Copperbelt. Chlorine is advected from the ocean and is accompanied by aeolian dust recirculating back to land from mid-oceanic regions. Biomass burning products are transported from the horn of Africa. Mineral dust from the Sahara is transported towards the Far East and then transported back within equatorial easterlies to Mt Kenya. This was observed during austral summer and coincided with the dying phase of 1997/98 El

  17. Kaiser's Systematic Indexing.

    ERIC Educational Resources Information Center

    Rodriguez, Robert D.

    1984-01-01

    Describes a system of subject indexing developed by Julius Kaiser (1868-1927) which is based on "concretes" and "processes" to govern the form of subject headings and subdivisions. Elements of amplification, guides for the subject index, and criticism of Kaiser's systematic indexing are noted. Five sources are given. (EJS)

  18. Automatic Versus Manual Indexing

    ERIC Educational Resources Information Center

    Vander Meulen, W. A.; Janssen, P. J. F. C.

    1977-01-01

    A comparative evaluation of results in terms of recall and precision from queries submitted to systems with automatic and manual subject indexing. Differences were attributed to query formulation. The effectiveness of automatic indexing was found equivalent to manual indexing. (Author/KP)

  19. The Europe 2020 Index

    ERIC Educational Resources Information Center

    Pasimeni, Paolo

    2013-01-01

    This paper presents a new index to quantify, measure and monitor the progress towards the objectives of the Europe 2020 strategy. This index is based on a set of relevant, accepted, credible, easy to monitor and robust indicators presented by the European Commission at the time the strategy was launched. The internal analysis of the index shows…

  20. Aerosol effects on deep convective clouds: impact of changes in aerosol size distribution and aerosol activation parameterization

    NASA Astrophysics Data System (ADS)

    Ekman, A. M. L.; Engström, A.; Söderberg, A.

    2010-03-01

    A cloud-resolving model including explicit aerosol physics and chemistry is used to study the impact of aerosols on deep convective strength. More specifically, by conducting six sensitivity series we examine how the complexity of the aerosol model, the size of the aerosols and the aerosol activation parameterization influence the aerosol-induced deep convective cloud sensitivity. Only aerosol effects on liquid droplet formation are considered. We find that an increased aerosol concentration generally results in stronger convection, which for the simulated case is in agreement with the conceptual model presented by Rosenfeld et al. (2008). However, there are two sensitivity series that do not display a monotonic increase in updraft velocity with increasing aerosol concentration. These exceptions illustrate the need to: 1) account for changes in evaporation processes and subsequent cooling when assessing aerosol effects on deep convective strength, 2) better understand graupel impaction scavenging of aerosols which may limit the number of CCN at a critical stage of cloud development and thereby dampen the convection, 3) increase our knowledge of aerosol recycling due to evaporation of cloud droplets. Furthermore, we find a significant difference in the aerosol-induced deep convective cloud sensitivity when using different complexities of the aerosol model and different aerosol activation parameterizations. For the simulated case, a 100% increase in aerosol concentration results in a difference in average updraft between the various sensitivity series which is as large as the average updraft increase itself. The model simulations also show that the change in graupel and rain formation is not necessarily directly proportional to the change in updraft velocity. For example, several of the sensitivity series display a decrease of the rain amount at the lowest model level with increasing updraft velocity. Finally, an increased number of aerosols in the Aitken mode (here

  1. Strategy to use the Terra Aerosol Information to Derive the Global Aerosol Radiative Forcing of Climate

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Tanre, Didier; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Terra will derive the aerosol optical thickness and properties. The aerosol properties can be used to distinguish between natural and human-made aerosol. In the polar orbit Terra will measure aerosol only once a day, around 10:30 am. How will we use this information to study the global radiative impacts of aerosol on climate? We shall present a strategy to address this problem. It includes the following steps: - From the Terra aerosol optical thickness and size distribution model we derive the effect of aerosol on reflection of solar radiation at the top of the atmosphere. In a sensitivity study we show that the effect of aerosol on solar fluxes can be derived 10 times more accurately from the MODIS data than derivation of the optical thickness itself. Applications to data over several regions will be given. - Using 1/2 million AERONET global data of aerosol spectral optical thickness we show that the aerosol optical thickness and properties during the Terra 10:30 pass are equivalent to the daily average. Due to the aerosol lifetime of several days measurements at this time of the day are enough to assess the daily impact of aerosol on radiation. - Aerosol impact on the top of the atmosphere is only part of the climate question. The INDOEX experiment showed that addressing the impact of aerosol on climate, requires also measurements of the aerosol forcing at the surface. This can be done by a combination of measurements of MODIS and AERONET data.

  2. Generation of a monodispersed aerosol

    NASA Technical Reports Server (NTRS)

    Schenck, H.; Mikasa, M.; Devicariis, R.

    1974-01-01

    The identity and laboratory test methods for the generation of a monodispersed aerosol are reported on, and are subjected to the following constraints and parameters; (1) size distribution; (2) specific gravity; (3) scattering properties; (4) costs; (5) production. The procedure called for the collection of information from the literature, commercial available products, and experts working in the field. The following topics were investigated: (1) aerosols; (2) air pollution -- analysis; (3) atomizers; (4) dispersion; (5) particles -- optics, size analysis; (6) smoke -- generators, density measurements; (7) sprays; (8) wind tunnels -- visualization.

  3. Real time infrared aerosol analyzer

    DOEpatents

    Johnson, Stanley A.; Reedy, Gerald T.; Kumar, Romesh

    1990-01-01

    Apparatus for analyzing aerosols in essentially real time includes a virtual impactor which separates coarse particles from fine and ultrafine particles in an aerosol sample. The coarse and ultrafine particles are captured in PTFE filters, and the fine particles impact onto an internal light reflection element. The composition and quantity of the particles on the PTFE filter and on the internal reflection element are measured by alternately passing infrared light through the filter and the internal light reflection element, and analyzing the light through infrared spectrophotometry to identify the particles in the sample.

  4. Aerosol Optical Properties Characterization By Means Of The CNR-IMAA Multi-Wavelength Raman Lidar

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

    A Raman/elastic lidar for tropospheric aerosol study is operational at CNR-IMAA (40°36'N, 15°44'E, 760 m above sea level) since May 2000 in the framework of EARLINET. Since August 2005, this system provides aerosol backscatter coefficient profiles at 1064 nm, and independent measurements of aerosol extinction and backscatter coefficient profiles at 355 and 532 nm. In this way, lidar ratio (i.e. extinction to backscatter ratio) profiles at 355 and 532 nm are also obtained. In addition, depolarization ratio measurements at 532 nm are obtained by means of detection of components of backscattered light polarized perpendicular and parallel to the direction of the linearly polarized transmitted laser beam. Depolarization ratio measurements provide information about shape and orientation of aerosolic particles, while lidar ratio measurements and wavelength dependences of both backscatter and extinction are important for aerosol characterization in terms of aerosol type and size. In addition, high quality multi-wavelength measurements (3 backscatter + 2 extinction) can allow the determination of microphysical aerosol properties (refractive index, single-scattering albedo and effective particles radii). Systematic measurements are performed three times per week according to the EARLINET schedule since May 2000, and further measurements are performed in order to investigate particular events, like dust intrusions, volcanic eruptions and forest fires. This extended dataset allows the optical characterization of aerosol located close to the surface, namely in the Planetary Boundary Layer, as well as in the free troposphere. In the free troposphere, an high occurrence of Saharan dust intrusions at CNR-IMAA (about 1 day of Saharan dust intrusion every 10 days) has been identified by means of back-trajectory analysis and in accordance with satellite images, because of the short distance from the Sahara region. In addition, CNR-IMAA is pretty close to Etna, the largest European

  5. Global and Seasonal Aerosol Optical Depths Derived From Ultraviolet Observations by Satellites (TOMS)

    NASA Technical Reports Server (NTRS)

    Herman, J. R.; Torres, O.

    1999-01-01

    It has been shown that absorbing aerosols (dust, smoke, volcanic ash) can be detected in the ultraviolet wavelengths (331 nm to 380 nm) from satellite observations (TOMS, Total Ozone Mapping Spectrometer) over both land and water. The theoretical basis for these observations and their conversions to optical depths is discussed in terms of an aerosol index AI or N-value residue (assigned positive for absorbing aerosols). The theoretical considerations show that negative values of the AI frequently represent the presence of non-absorbing aerosols (NA) in the troposphere (mostly pollution in the form of sulfates, hydrocarbons, etc., and some natural sulfate aerosols) with particle sizes near 0.1 to 0.2 microns or less. The detection of small-particle non-absorbing aerosols from the measured backscattered radiances is based on the observed wavelength dependence from Mie scattering after the background Rayleigh scattering is subtracted. The Mie scattering from larger particles, 1 micron or more (e.g., cloud water droplets) has too small a wavelength dependence to be detected by this method. In regions that are mostly cloud free, aerosols of all sizes can be seen in the single channel 380 nm or 360 nm radiance data. The most prominent Al feature observed is the strong asymmetry in aerosol amount between the Northern and Southern Hemispheres, with the large majority of NA occurring above 20degN latitude. The maximum values of non-absorbing aerosols are observed over the eastern U.S. and most of western Europe corresponding to the areas of highest industrial pollution. Annual cycles in the amount of NA are observed over Europe and North America with maxima occurring in the summer corresponding to times of minimum wind transport. Similarly, the maxima in the winter over the Atlantic Ocean occurs because of wind borne transport from the land. Most regions of the world have the maximum amount of non-absorbing aerosol in the December to January period except for the eastern

  6. Optical properties of aerosols during APEX and ACE-Asia experiments

    NASA Astrophysics Data System (ADS)

    Sano, Itaru; Mukai, Sonoyo; Okada, Yasuhiko; Holben, Brent N.; Ohta, Sachio; Takamura, Tamio

    2003-12-01

    Sun/sky photometry and polarimetry of atmospheric light have been undertaken by multispectral photometers (CE-318-1 and -2, Cimel Electronique, France) and a polarimeter (PSR-1000, Opto Research, Japan) over Amami, Noto, and Shirahama, Japan, during APEX-E1, -E2, and ACE-Asia field campaigns. Radiometers provide us with the optical thickness of aerosols and Ångström exponent. Other aerosol characteristics, e.g., size distribution, refractive index, etc., are retrieved based on each inversion method corresponding each equipment. The former takes a standard AERONET processing, and the latter is according to our own procedure to analyze the polarimetry with PSR-1000. After several aerosol parameters are derived, the HYSPLIT4 backward trajectory analysis is adopted to search the origin of aerosols. It is shown from these ground measurements that aerosol optical thickness, Ångström exponent, and refractive index are classified into two typical categories as a background type detected in winter, and a soil dust type appeared in Asian dust events in spring. Further, it is found that the obtained size distribution of Asian dust indicates the dominance of large particles.

  7. Multiwavelength Comparison of Modeled and Measured Remote Tropospheric Aerosol Backscatter Over Pacific Ocean

    NASA Technical Reports Server (NTRS)

    Cutten, D. R.; Pueschel, R. F.; Srivastava, V.; Clarke, A. D.; Rothermel, J.; Spinhirne, J. D.; Menzies, R. T.

    1996-01-01

    Aerosol concentrations and size distributions in the middle and upper troposphere over the remote Pacific Ocean were measured with a forward scattering spectrometer probe (FSSP) on the NASA DC-8 aircraft during NASA's Global Backscatter Experiment (GLOBE) in May-June 1990. The FSSP size channels were recalibrated based on refractive index estimates from flight-level aerosol volatility measurements with a collocated laser optical particle counter (LOPC). The recalibrated FSSP size distributions were averaged over 100-s intervals, fitted with lo-normal distributions and used to calculate aerosol backscatter coefficients at selected wavelengths. The FSSP-derived backscatter estimates were averaged over 300-s intervals to reduce large random fluctuations. The smoothed FSSP aerosol backscatter coefficients were then compared with LOPC-derived backscatter values and with backscatter measured at or near flight level from four lidar systems operating at 0.53, 1.06, 9.11, 9.25, and 10.59 micrometers. Agreement between FSSP-derived and lidar-measured backscatter was generally best at flight level in homogeneous aerosol fields and at high backscatter values. FSSP data often underestimated low backscatter values especially at the longer wavelengths due to poor counting statistics for larger particles (greater than 0.8 micrometers diameter) that usually dominate aerosol backscatter at these wavelengths. FSSP data also underestimated backscatter at shorter wavelengths when particles smaller than the FSSP lower cutoff diameter (0.35 micrometers) made significant contributions to the total backscatter.

  8. Light Absorption of Stratospheric Aerosols: Long-Term Trend and Contribution by Aircraft

    NASA Technical Reports Server (NTRS)

    Pueschel , R. F.; Gore, Waren J. Y. (Technical Monitor)

    1997-01-01

    Measurements of aerosol light-absorption coefficients are useful for studies of radiative transfer and heating rates. Ogren appears to have published the first light- absorption coefficients in the stratosphere in 1981, followed by Clarke in 1983 and Pueschel in 1992. Because most stratospheric soot appears to be due to aircraft operations, application of an aircraft soot aerosol emission index to projected fuel consumption suggests a threefold increase of soot loading and light absorption by 2025. Together, those four data sets indicate an increase in mid-visible light extinction at a rate of 6 % per year. This trend is similar to the increase per year of sulfuric acid aerosol and of commercial fleet size. The proportionality between stepped-up aircraft operations above the tropopause and increases in stratospheric soot and sulfuric acid aerosol implicate aircraft as a source of stratospheric pollution. Because the strongly light-absorbing soot and the predominantly light-scattering sulfuric acid aerosol increase at similar rates, however, the mid-visible stratospheric aerosol single scatter albedo is expected to remain constant and not approach a critical value of 0.98 at which stratospheric cooling could change to warming.

  9. Aerosols of Mongolian arid area

    NASA Astrophysics Data System (ADS)

    Golobokova, L.; Marinayte, I.; Zhamsueva, G.

    2012-04-01

    Sampling was performed in July-August 2005-2010 at Station Sain Shand (44°54'N, 110°07'E) in the Gobi desert (1000 m a.s.l.), West Mongolia. Aerosol samples were collected with a high volume sampler PM 10 (Andersen Instruments Inc., USA) onto Whatman-41 filters. The substance was extracted from the filters by de-ionized water. The solution was screened through an acetate-cellulose filter with 0.2 micron pore size. Ions of ammonium, sodium, potassium, magnesium, and calcium, as well as sulphate ions, nitrate ions, hydrocarbonate, chloride ions were determined in the filtrate by means of an atomic adsorption spectrometer Carl Zeiss Jena (Germany), a high performance liquid chromatographer «Milichrome A-02» (Russia), and an ionic chromatographer ICS-3000 (Dionex, USA). The PAH fraction was separated from aerosol samples using hexane extraction at room temperature under UV environment. The extract was concentrated to 0.1-0.2 ml and analysed by a mass-spectrometer "Agilent, GC 6890, MSD 5973 Network". Analysis of concentrations of aerosols components, their correlation ratios, and meteorological modeling show that the main factor affecting chemical composition of aerosols is a flow of contaminants transferred by air masses to the sampling area mainly from the south and south-east, as well as wind conditions of the area, dust storms in particular. Sulphate, nitrate, and ammonium are major ions in aerosol particles at Station Sain Shand. Dust-borne aerosol is known to be a sorbent for both mineral and organic admixtures. Polycyclic aromatic hydrocarbons (PAH) being among superecotoxicants play an important role among resistant organic substances. PAH concentrations were determined in the samples collected in 2010. All aerosol samples contained dominant PAHs with 5-6 benzene rings ( (benze(k)fluoranthen, benze(b)flouranthen, benze(a)pyren, benze(?)pyren, perylene, benze(g,h,i)perylene, and indene(1,2,3-c,d)pyrene). Their total quantity varied between 42 and 90

  10. A thermoluminescent method for aerosol characterization

    NASA Technical Reports Server (NTRS)

    Long, E. R., Jr.; Rogowski, R. S.

    1976-01-01

    A thermoluminescent method has been used to study the interactions of aerosols with ozone. The preliminary results show that ozone reacts with many compounds found in aerosols, and that the thermoluminescence curves obtained from ozonated aerosols are characteristic of the aerosol. The results suggest several important applications of the thermoluminescent method: development of a detector for identification of effluent sources; a sensitive experimental tool for study of heterogeneous chemistry; evaluation of importance of aerosols in atmospheric chemistry; and study of formation of toxic, electronically excited species in airborne particles.

  11. Contribution of methane to aerosol carbon mass

    NASA Astrophysics Data System (ADS)

    Bianchi, F.; Barmet, P.; Stirnweis, L.; El Haddad, I.; Platt, S. M.; Saurer, M.; Lötscher, C.; Siegwolf, R.; Bigi, A.; Hoyle, C. R.; DeCarlo, P. F.; Slowik, J. G.; Prévôt, A. S. H.; Baltensperger, U.; Dommen, J.

    2016-09-01

    Small volatile organic compounds (VOC) such as methane (CH4) have long been considered non-relevant to aerosol formation due to the high volatility of their oxidation products. However, even low aerosol yields from CH4, the most abundant VOC in the atmosphere, would contribute significantly to the total particulate carbon budget. In this study, organic aerosol (OA) mass yields from CH4 oxidation were evaluated at the Paul Scherrer Institute (PSI) smog chamber in the presence of inorganic and organic seed aerosols. Using labeled 13C methane, we could detect its oxidation products in the aerosol phase, with yields up to 0.09

  12. Infrared Absorption by Atmospheric Aerosols in Mexico City during MILAGRO.

    NASA Astrophysics Data System (ADS)

    Kelley, K. L.; Mangu, A.; Gaffney, J. S.; Marley, N. A.

    2007-12-01

    found as colloidal materials in surface and groundwaters (4). Examples of the IR spectra obtained and variance as a function of time at the two sites will be presented. The spectra are taken in Kubelka - Munk format, which also allows the infrared absorption strengths to be evaluated as function of wavelength. The wavelength dependence of the aerosol complex refractive index (m = n + ik) in the infrared spectral region is determined by application of the Kramers Kronig function. The importance of the aerosol absorption in the infrared spectral region to radiative forcing will be discussed. 1. N.A. Marley, J.S. Gaffney, and M.M. Cunningham,Environ. Sci. Technol. 27 2864-2869 (1993). 2. N.A. Marley, J.S. Gaffney, and M.M. Cunningham, Spectroscopy 7 44-53 (1992). 3. J.S. Gaffney and N.A. Marley, Atmospheric Environment, New Directions contribution, 32, 2873-2874 (1998). 4. N.A. Marley, J.S. Gaffney, and K.A. Orlandini, Chapter 7 in Humic/Fulvic Acids and Organic Colloidal Materials in the Environment, ACS Symposium Series 651, American Chemical Society, Washington, D.C., pp. 96-107, 1996. This work was performed as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX- Mex) under the support of the Atmospheric Science Program. This research was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64328.

  13. Retrieval of aerosol microphysical properties from AERONET photopolarimetric measurements: 1. Information content analysis

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoguang; Wang, Jun

    2015-07-01

    This paper is the first part of a two-part study that aims to retrieve aerosol particle size distribution (PSD) and refractive index from the multispectral and multiangular polarimetric measurements taken by the new-generation Sun photometer as part of the Aerosol Robotic Network (AERONET). It provides theoretical analysis and guidance to the companion study in which we have developed an inversion algorithm for retrieving 22 aerosol microphysical parameters associated with a bimodal PSD function from real AERONET measurements. Our theoretical analysis starts with generating the synthetic measurements at four spectral bands (440, 675, 870, and 1020 nm) with a Unified Linearized Vector Radiative Transfer Model for various types of spherical aerosol particles. Subsequently, the quantitative information content for retrieving aerosol parameters is investigated in four observation scenarios, i.e., I1, I2, P1, and P2. Measurements in the scenario (I1) comprise the solar direct radiances and almucantar radiances that are used in the current AERONET operational inversion algorithm. The other three scenarios include different additional measurements: (I2) the solar principal plane radiances, (P1) the solar principal plane radiances and polarization, and (P2) the solar almucantar polarization. Results indicate that adding polarization measurements can increase the degree of freedom for signal by 2-5 in the scenario P1, while not as much of an increase is found in the scenarios I2 and P2. Correspondingly, smallest retrieval errors are found in the scenario P1: 2.3% (2.9%) for the fine-mode (coarse-mode) aerosol volume concentration, 1.3% (3.5%) for the effective radius, 7.2% (12%) for the effective variance, 0.005 (0.035) for the real-part refractive index, and 0.019 (0.068) for the single-scattering albedo. These errors represent a reduction from their counterparts in scenario I1 of 79% (57%), 76% (49%), 69% (52%), 66% (46%), and 49% (20%), respectively. We further

  14. Global modeling of tropospheric iodine aerosol

    NASA Astrophysics Data System (ADS)

    Sherwen, Tomás. M.; Evans, Mat J.; Spracklen, Dominick V.; Carpenter, Lucy J.; Chance, Rosie; Baker, Alex R.; Schmidt, Johan A.; Breider, Thomas J.

    2016-09-01

    Natural aerosols play a central role in the Earth system. The conversion of dimethyl sulfide to sulfuric acid is the dominant source of oceanic secondary aerosol. Ocean emitted iodine can also produce aerosol. Using a GEOS-Chem model, we present a simulation of iodine aerosol. The simulation compares well with the limited observational data set. Iodine aerosol concentrations are highest in the tropical marine boundary layer (MBL) averaging 5.2 ng (I) m-3 with monthly maximum concentrations of 90 ng (I) m-3. These masses are small compared to sulfate (0.75% of MBL burden, up to 11% regionally) but are more significant compared to dimethyl sulfide sourced sulfate (3% of the MBL burden, up to 101% regionally). In the preindustrial, iodine aerosol makes up 0.88% of the MBL burden sulfate mass and regionally up to 21%. Iodine aerosol may be an important regional mechanism for ocean-atmosphere interaction.

  15. Aerosol Behavior Log-Normal Distribution Model.

    SciTech Connect

    GIESEKE, J. A.

    2001-10-22

    HAARM3, an acronym for Heterogeneous Aerosol Agglomeration Revised Model 3, is the third program in the HAARM series developed to predict the time-dependent behavior of radioactive aerosols under postulated LMFBR accident conditions. HAARM3 was developed to include mechanisms of aerosol growth and removal which had not been accounted for in the earlier models. In addition, experimental measurements obtained on sodium oxide aerosols have been incorporated in the code. As in HAARM2, containment gas temperature, pressure, and temperature gradients normal to interior surfaces are permitted to vary with time. The effects of reduced density on sodium oxide agglomerate behavior and of nonspherical shape of particles on aerosol behavior mechanisms are taken into account, and aerosol agglomeration due to turbulent air motion is considered. Also included is a capability to calculate aerosol concentration attenuation factors and to restart problems requiring long computing times.

  16. Assessment of OMI near-UV aerosol optical depth over Central and East Asia

    NASA Astrophysics Data System (ADS)

    Zhang, Wenhao; Gu, Xingfa; Xu, Hui; Yu, Tao; Zheng, Fengjie

    2016-01-01

    Several essential improvements have been made in recent Ozone Monitoring Instrument (OMI) near-ultraviolet (UV) aerosol retrieval algorithm version (OMAERUV version 1.4.2), but few regional validations for its aerosol optical depth (AOD) product are conducted. This paper assessed the OMAERUV AOD product over Central and East Asia. The OMAERUV Level 2.0 AOD product was compared with Aerosol Robotic Network (AERONET) Level 2.0 direct Sun AOD measurement over 10 years (2005-2014) at 27 selected AERONET sites. A combined comparison of OMAERUV-AERONET AOD at 25 (2) sites was carried out and yielded correlation coefficient (ρ) of 0.63 (0.77), slope of 0.53 (0.57), y intercept of 0.18 (0.13), and 50.71% (57.24%) OMAERUV AOD fall within the expected uncertainty boundary (larger by 0.1 or ±30%) at 380 nm (440 nm). The more accurate (ρ > 0.70) OMAERUV retrievals are reported over eastern and northern China and South Korea. The two primary reasons for the underestimation of OMAERUV AOD over China are as follows: (1) the use of single-channel (388 nm) retrieval method retrieves scattering AOD and not total AOD, and (2) the spectral dependence of the imaginary part of the refractive index in the near-UV region assumed in the algorithm may not be representative of aerosols found over China. The comparisons for three predominant aerosol types indicate that smoke aerosol exhibits the best performance, followed by dust and nonabsorbing aerosol. It is consistent with the characteristic of near-UV wavelength that it is more sensitive to absorbent particles. The comprehensive yearly (2005-2014) comparison at 25 sites and comparison between two periods (2005-2006 and 2009-2014) at selected four sites show no discernible decrease of temporal trend, which indicates that the OMAERUV algorithm successfully maintains its quality of aerosol product despite post-2008 row anomaly instrument problem.

  17. Direct radiative effect due to brownness in organic carbon aerosols generated from biomass combustion

    NASA Astrophysics Data System (ADS)

    Rathod, T. D.; Sahu, S. K.; Tiwari, M.; Pandit, G. G.

    2016-12-01

    We report the enhancement in the direct radiative effect due the presence of Brown carbon (BrC) as a part of organic carbon aerosols. The optical properties of organic carbon aerosols generated from pyrolytic combustion of mango tree wood (Magnifera Indica) and dung cake at different temperatures were considered. Mie codes were used to calculate absorption and scattering coefficients coupled with experimentally derived imaginary complex refractive index. The direct radiative effect (DRE) for sampled organic carbon aerosols was estimated using a wavelength dependent radiative transfer equation. The BrC DRE was estimated taking virtually non absorbing organic aerosols as reference. The BrC DRE from wood and dung cake was compared at different combustion temperatures and conditions. The BrC contributed positively to the direct top of the atmosphere radiative effect. Dung cake generated BrC aerosols were found to be strongly light absorbing as compared to BrC from wood combustion. It was noted that radiative effects of BrC from wood depended on its generation temperature and conditions. For BrC aerosols from dung cake such strong dependence was not observed. The average BrC aerosol DRE values were 1.53±0.76 W g-1 and 17.84±6.45 W g-1 for wood and dung cake respectively. The DRE contribution of BrC aerosols came mainly (67-90%) from visible light absorption though they exhibited strong absorption in shorter wavelengths of the UV-visible spectrum.

  18. Radiative effects of absorbing aerosols over northeastern India: Observations and model simulations

    NASA Astrophysics Data System (ADS)

    Gogoi, Mukunda M.; Babu, S. Suresh; Moorthy, K. Krishna; Bhuyan, Pradip Kumar; Pathak, Binita; Subba, Tamanna; Chutia, Lakhima; Kundu, Shyam Sundar; Bharali, Chandrakala; Borgohain, Arup; Guha, Anirban; De, Barin Kumar; Singh, Brajamani; Chin, Mian

    2017-01-01

    Multiyear measurements of spectral properties of aerosol absorption are examined over four geographically distinct locations of northeastern India. Results indicated significant spatiotemporal variation in aerosol absorption coefficients (σabs) with highest values in winter and lowest in monsoon. The western parts of the region, close to the outflow of Indo-Gangetic Plains, showed higher values of σabs and black carbon (BC) concentration—mostly associated with fossil fuel combustion. But, the eastern parts showed higher contributions from biomass-burning aerosols, as much as 20-25% to the total aerosol absorption, conspicuously during premonsoon season. This is attributed to a large number of burning activities over the Southeast Asian region, as depicted from Moderate Resolution Imaging Spectroradiometer fire count maps, whose spatial extent and magnitude peaks during March/April. The nearly consistent high values of aerosol index (AI) and layer height from Ozone Monitoring Instrument indicate the presence of absorbing aerosols in the upper atmosphere. The observed seasonality has been captured fairly well by Goddard Chemistry Aerosol Radiation and Transport (GOCART) as well as Weather Research and Forecasting-Chemistry (WRF-Chem) model simulations. The ratio of column-integrated optical depths due to particulate organic matter and BC from GOCART showed good coincidence with satellite-based observations, indicating the increased vertical dispersion of absorbing aerosols, probably by the additional local convection due to higher fire radiative power caused by the intense biomass-burning activities. In the WRF-Chem though underperformed by different magnitude in winter, the values are closer or overestimated near the burnt areas. Atmospheric forcing due to BC was highest ( 30 Wm-2) over the western part associated with the fossil fuel combustion.

  19. Satellite Detection of Smoke Aerosols Over a Snow/Ice Surface by TOMS

    NASA Technical Reports Server (NTRS)

    Hsu, N. Christina; Herman, Jay R.; Gleason, J. F.; Torres, O.; Seftor, C. J.

    1998-01-01

    The use of TOMS (Total Ozone Mapping Spectrometer) satellite data demonstrates the recently developed technique of using satellite UV radiance measurements to detect absorbing tropospheric aerosols is effective over snow/ice surfaces. Instead of the traditional single wavelength (visible or infrared) method of measuring tropospheric aerosols, this method takes advantage of the wavelength dependent reduction in the backscattered radiance due to the presence of absorbing aerosols over snow/ice surfaces. An example of the resulting aerosol distribution derived from TOMS data is shown for an August 1998 event in which smoke generated by Canadian forest fires drifts over and across Greenland. As the smoke plume moved over Greenland, the TOMS observed 380 nm reflectivity over the snow/ice surface dropped drastically from 90-100% down to 30-40%. To study the effects of this smoke plume in both the UV and visible regions of the spectrum, we compared a smoke-laden spectrum taken over Greenland by the high spectral resolution (300 to 800 nm) GOME instrument with one that is aerosol-free. We also discuss the results of modeling the darkening effects of various types of absorbing aerosols over snow/ice surfaces using a radiative transfer code. Finally, we investigated the history of such events by looking at the nearly twenty year record of TOMS aerosol index measurements and found that there is a large interannual variability in the amount of smoke aerosols observed over Greenland. This information will be available for studies of radiation and transport properties in the Arctic.

  20. Assessment of aerosol-cloud interactions in the ECHAM6-HAM GCM and the Aerosol_cci/Cloud_cci (A)ATSR dataset

    NASA Astrophysics Data System (ADS)

    Neubauer, David; Lohmann, Ulrike; Christensen, Matthew; Poulsen, Caroline

    2016-04-01

    Aerosol-cloud interactions (ACI) are uncertain and the estimates of the ACI effective radiative forcing magnitude show a large variability. Studies using present day variability in satellite data to infer ACI, or that constrain model parameterizations to better agree with satellite observations find a less negative ACI radiative forcing than purely model based studies. Next to the problematic use of present day variability as a substitute for anthropogenic change, the scale at which the analysis of the responses of cloud properties to changes in aerosol is done could be a reason for the discrepancy in forcing estimates if the analysis/observational scales differ substantially from the process scale. The projects of the Climate Change Initiative (CCI) programme of ESA aim at producing long time series of satellite data of essential climate variables and give the opportunity to produce products for susceptibilities of aerosol properties from Aerosol_cci and cloud properties from Cloud_cci from high resolution datasets. Within the Aerosol_cci project these susceptibilities derived from high resolution (A)ATSR datasets with a nearest neighbour approach are compared to susceptibilities from the global aerosol climate model ECHAM6-HAM. Next to the new satellite products a relatively fine analysis scale is used and the clouds are separated in different environmental regimes to reduce smoothing or spurious effects by aggregation of data. Susceptibilities and forcing estimates differ between the (A)ATSR datasets and ECHAM6-HAM with the model showing stronger susceptibilities and ACI radiative forcing in agreement with previous estimates in the literature. There is a large difference in susceptibilities between precipitating and non-precipitating clouds in the satellite as well as the model data but there is no decrease in liquid water path with increasing aerosol index as has been reported in the literature for A-train satellite data. The liquid water path susceptibility of

  1. Near UV Aerosol Group Report

    NASA Technical Reports Server (NTRS)

    Torres, Omar

    2013-01-01

    2012-13 Report of research on aerosol and cloud remote sensing using UV observations. The document was presented at the 2013 AEROCENTER Annual Meeting held at the GSFC Visitors Center, May 31, 2013. The Organizers of the meeting are posting the talks to the public Aerocentr website, after the meeting.

  2. Airborne Atmospheric Aerosol Measurement System

    NASA Astrophysics Data System (ADS)

    Ahn, K.; Park, Y.; Eun, H.; Lee, H.

    2015-12-01

    It is important to understand the atmospheric aerosols compositions and size distributions since they greatly affect the environment and human health. Particles in the convection layer have been a great concern in global climate changes. To understand these characteristics satellite, aircraft, and radio sonde measurement methods have usually been used. An aircraft aerosol sampling using a filter and/or impactor was the method commonly used (Jay, 2003). However, the flight speed particle sampling had some technical limitations (Hermann, 2001). Moreover, the flight legal limit, altitude, prohibited airspace, flight time, and cost was another demerit. To overcome some of these restrictions, Tethered Balloon Package System (T.B.P.S.) and Recoverable Sonde System(R.S.S.) were developed with a very light optical particle counter (OPC), impactor, and condensation particle counter (CPC). Not only does it collect and measure atmospheric aerosols depending on altitudes, but it also monitors the atmospheric conditions, temperature, humidity, wind velocity, pressure, GPS data, during the measurement (Eun, 2013). In this research, atmospheric aerosol measurement using T.B.P.S. in Ansan area is performed and the measurement results will be presented. The system can also be mounted to an unmanned aerial vehicle (UAV) and create an aerial particle concentration map. Finally, we will present measurement data using Tethered Balloon Package System (T.B.P.S.) and R.S.S (Recoverable Sonde System).

  3. Zero-gravity aerosol behavior

    NASA Technical Reports Server (NTRS)

    Edwards, H. W.

    1981-01-01

    The feasibility and scientific benefits of a zero gravity aerosol study in an orbiting laboratory were examined. A macroscopic model was devised to deal with the simultaneous effects of diffusion and coagulation of particles in the confined aerosol. An analytical solution was found by treating the particle coagulation and diffusion constants as ensemble parameters and employing a transformation of variables. The solution was used to carry out simulated zero gravity aerosol decay experiments in a compact cylindrical chamber. The results demonstrate that the limitations of physical space and time imposed by the orbital situation are not prohibitive in terms of observing the history of an aerosol confined under zero gravity conditions. While the absence of convective effects would be a definite benefit for the experiment, the mathematical complexity of the problem is not greatly reduced when the gravitational term drops out of the equation. Since the model does not deal directly with the evolution of the particle size distribution, it may be desirable to develop more detailed models before undertaking an orbital experiment.

  4. High Concentration Standard Aerosol Generator.

    DTIC Science & Technology

    1985-07-31

    materials. In addition to material problems, many liquids are extremely flammable or explosive when aerosolized. This can be checked by putting a small...Hochriner. D. (1975) Stub 3A 440-445. St6ber, W. Flachsbart, H. and Hochramn, D. (1970) Staub 3^, 277. Yoshida. H. Fujii, K. Yomimoto, Y. Masuda. H. and

  5. Characterization of Aerosols Containing Microcystin

    PubMed Central

    Cheng, Yung Sung; Zhou, Yue; Irvin, C. Mitch; Kirkpatrick, Barbara; Backer, Lorraine C.

    2007-01-01

    Toxic blooms of cyanobacteria are ubiquitous in both freshwater and brackish water sources throughout the world. One class of cyanobacterial toxins, called microcystins, is cyclic peptides. In addition to ingestion and dermal, inhalation is a likely route of human exposure. A significant increase in reporting of minor symptoms, particularly respiratory symptoms was associated with exposure to higher levels of cyanobacteria during recreational activities. Algae cells, bacteria, and waterborne toxins can be aerosolized by a bubble-bursting process with a wind-driven white-capped wave mechanism. The purposes of this study were to: evaluate sampling and analysis techniques for microcystin aerosol, produce aerosol droplets containing microcystin in the laboratory, and deploy the sampling instruments in field studies. A high-volume impactor and an IOM filter sampler were tried first in the laboratory to collect droplets containing microcystins. Samples were extracted and analyzed for microcystin using an ELISA method. The laboratory study showed that cyanotoxins in water could be transferred to air via a bubble-bursting process. The droplets containing microcystins showed a bimodal size distribution with the mass median aerodynamic diameter (MMAD) of 1.4 and 27.8 μm. The sampling and analysis methods were successfully used in a pilot field study to measure microcystin aerosol in situ. PMID:18463733

  6. NASA's Aerosol Sampling Experiment Summary

    NASA Technical Reports Server (NTRS)

    Meyer, Marit E.

    2016-01-01

    In a spacecraft cabin environment, the size range of indoor aerosols is much larger and they persist longer than on Earth because they are not removed by gravitational settling. A previous aerosol experiment in 1991 documented that over 90 of the mass concentration of particles in the NASA Space Shuttle air were between 10 m and 100 m based on measurements with a multi-stage virtual impactor and a nephelometer (Liu et al. 1991). While the now-retired Space Shuttle had short duration missions (less than two weeks), the International Space Station (ISS) has been continually inhabited by astronauts for over a decade. High concentrations of inhalable particles on ISS are potentially responsible for crew complaints of respiratory and eye irritation and comments about 'dusty' air. Air filtration is the current control strategy for airborne particles on the ISS, and filtration modeling, performed for engineering and design validation of the air revitalization system in ISS, predicted that PM requirements would be met. However, aerosol monitoring has never been performed on the ISS to verify PM levels. A flight experiment is in preparation which will provide data on particulate matter in ISS ambient air. Particles will be collected with a thermophoretic sampler as well as with passive samplers which will extend the particle size range of sampling. Samples will be returned to Earth for chemical and microscopic analyses, providing the first aerosol data for ISS ambient air.

  7. Optical Characterization of Tropospheric Aerosols.

    DTIC Science & Technology

    1987-09-01

    Transmission of Light Through Fog," Phys. Rev. Vol. 38, p 159 (1931). 27. Kerker, M., Matijevic , E., Espenscheid, W. F., Farone, W. A., and Kitani, S...Espensheid, W. F., Matijevic , E., and Kerker, M., "Aerosol Studies by Light Scattering. III. Preparation and Particle Size Analysis of Sodium Chloride

  8. Aerosol backscatter studies supporting LAWS

    NASA Technical Reports Server (NTRS)

    Rothermel, Jeffry

    1989-01-01

    Optimized Royal Signals and Radar Establishment (RSRE), Laser True Airspeed System (LATAS) algorithm for low backscatter conditions was developed. The algorithm converts backscatter intensity measurements from focused continuous-wave (CW) airborne Doppler lidar into backscatter coefficients. The performance of optimized algorithm under marginal backscatter signal conditions was evaluated. The 10.6 micron CO2 aerosol backscatter climatologies were statistically analyzed. Climatologies reveal clean background aerosol mode near 10(exp -10)/kg/sq m/sr (mixing ratio units) through middle and upper troposhere, convective mode associated with planetary boundary layer convective activity, and stratospheric mode associated with volcanically-generated aerosols. Properties of clean background mode are critical to design and simulation studies of Laser Atmospheric Wind Sounder (LAWS), a MSFC facility Instrument on the Earth Observing System (Eos). Previous intercomparisons suggested correlation between aerosol backscatter at CO2 wavelength and water vapor. Field measurements of backscatter profiles with MSFC ground-based Doppler lidar system (GBDLS) were initiated in late FY-88 to coincide with independent program of local rawinsonde releases and overflights by Multi-spectral Atmospheric Mapping Sensor (MAMS), a multi-channel infrared radiometer capable of measuring horizontal and vertical moisture distributions. Design and performance simulation studies for LAWS would benefit from the existence of a relationship between backscatter and water vapor.

  9. Atmospheric Aerosol Scattering Background Observations

    DTIC Science & Technology

    1988-06-14

    condensation nuclei in the atmosphere, Nature 51:1259- 1267. 16. Whitby , K.T. (1975) Modeling of Atmospheric Aerosol Particle Size Distribution, Prog. Rep...Meteorol. 18:501-509. 33 15. Went, F.W. (1964) The nature of Aitkin condensation nuclei In the atmosphere, Nature 51:1259- 1267. 16. Whitby . K.T. (1975

  10. Aerosol and monsoon climate interactions over Asia: AEROSOL AND MONSOON CLIMATE INTERACTIONS

    SciTech Connect

    Li, Zhanqing; Lau, W. K. -M.; Ramanathan, V.; Wu, G.; Ding, Y.; Manoj, M. G.; Liu, J.; Qian, Y.; Li, J.; Zhou, T.; Fan, J.; Rosenfeld, D.; Ming, Y.; Wang, Y.; Huang, J.; Wang, B.; Xu, X.; Lee, S. -S.; Cribb, M.; Zhang, F.; Yang, X.; Zhao, C.; Takemura, T.; Wang, K.; Xia, X.; Yin, Y.; Zhang, H.; Guo, J.; Zhai, P. M.; Sugimoto, N.; Babu, S. S.; Brasseur, G. P.

    2016-11-15

    Asian monsoons and aerosols have been studied extensively which are intertwined in influencing the climate of Asia. This paper provides a comprehensive review of ample studies on Asian aerosol, monsoon and their interactions. The region is the primary source of aerosol emissions of varies species, influenced by distinct weather and climatic regimes. On continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulation. The atmospheric thermodynamic state may also be altered by the aerosol serving as cloud condensation nuclei or ice nuclei. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of numerous monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from biomass burning, and biogenic aerosols from vegetation are considered integral components of an intrinsic aerosol-monsoon climate system, subject to external forcings of global warming, anthropogenic aerosols, and land use and change. Future research on aerosol-monsoon interactions calls for an integrated approach and international collaborations based on long-term sustained observations, process measurements, and improved models, as well as using observations to constrain model simulations and projections.

  11. How does the synergy between GEO-CAPE and GOES-R improve the retrieval of aerosol properties and the estimate of aerosol radiative forcing?

    NASA Astrophysics Data System (ADS)

    Wang, J.; Zeng, J.; Xu, X.; Spurr, R. J.; Liu, X.

    2011-12-01

    As a geostationary satellite, GEO-CAPE will monitor the same region constantly with same viewing zenith angle; but the change of solar zenith angle during the course of a day provides GEO-CAPE an opportunity to observe the same area at multi-scattering angles. This multi-angle observation from GEO-CAPE can be further combined with similar multi-angle observation from GOES-R, offering the unprecedented opportunity to conduct the retrieval of aerosol properties beyond the aerosol optical depth. In this study, we use the state-of-the-art linearized vector radative transfer model (VLIDORT), linearized Mie code, and linearized T-matrix code in conjunction with inversion theory and HITRAN database to study how the multi-angle synergy between GEO-CAPE and GOES-R can improve the retrieval of aerosol properties and the estimate of aerosol radiative forcing. Our numerical framework is capable to study the degree of freedoms in the aerosol retrieval space for any given set of synthetic or real satellite observation. Our preliminary studies showed that a combined use of GEO-CAPE and GOES-R multi-angle observation can offer unique opportunity to retrieve not only aerosol optical depth but also ~2-3 out of 4 aerosol parameters (e.g., effective radius, effective variance, and refractive index), depending on number of wavelengths and angles used in the retrieval. The retrieved parameter and the corresponding retrieval uncertainty are input into the radiative transfer model to compute the aerosol radiative forcing and estimate the associated uncertainty in the forcing calculations. These results are then compared against another set of forcing calculations that use the current knowledge of satellite-based aerosol parameters and uncertainties as inputs. The comparison is stratified as a function of many confounding parameters (such as surface reflectance, satellite-earth geometry, calibration accuracy) for different air mass types (e.g., urban, rural, or a mixture of both, etc) to

  12. The MODIS Aerosol Algorithm, Products and Validation

    NASA Technical Reports Server (NTRS)

    Remer, L. A.; Kaufman, Y. J.; Tanre, D.; Mattoo, S.; Chu, D. A.; Martins, J. V.; Li, R.-R.; Ichoku, C.; Levy, R. C.; Kleidman, R. G.

    2003-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) aboard both NASA's Terra and Aqua satellites is making near global daily observations of the earth in a wide spectral range. These measurements are used to derive spectral aerosol optical thickness and aerosol size parameters over both land and ocean. The aerosol products available over land include aerosol optical thickness at three visible wavelengths, a measure of the fraction of aerosol optical thickness attributed to the fine mode and several derived parameters including reflected spectral solar flux at top of atmosphere. Over ocean, the aerosol optical thickness is provided in seven wavelengths from 0.47 microns to 2.13 microns. In addition, quantitative aerosol size information includes effective radius of the aerosol and quantitative fraction of optical thickness attributed to the fine mode. Spectral aerosol flux, mass concentration and number of cloud condensation nuclei round out the list of available aerosol products over the ocean. The spectral optical thickness and effective radius of the aerosol over the ocean are validated by comparison with two years of AERONET data gleaned from 133 AERONET stations. 8000 MODIS aerosol retrievals colocated with AERONET measurements confirm that one-standard deviation of MODIS optical thickness retrievals fall within the predicted uncertainty of delta tauapproximately equal to plus or minus 0.03 plus or minus 0.05 tau over ocean and delta tay equal to plus or minus 0.05 plus or minus 0.15 tau over land. 271 MODIS aerosol retrievals co-located with AERONET inversions at island and coastal sites suggest that one-standard deviation of MODIS effective radius retrievals falls within delta r_eff approximately equal to 0.11 microns. The accuracy of the MODIS retrievals suggests that the product can be used to help narrow the uncertainties associated with aerosol radiative forcing of global climate.

  13. Aerosol Absorption Measurements in MILAGRO.

    NASA Astrophysics Data System (ADS)

    Gaffney, J. S.; Marley, N. A.; Arnott, W. P.; Paredes-Miranda, L.; Barnard, J. C.

    2007-12-01

    During the month of March 2006, a number of instruments were used to determine the absorption characteristics of aerosols found in the Mexico City Megacity and nearby Valley of Mexico. These measurements were taken as part of the Department of Energy's Megacity Aerosol Experiment - Mexico City (MAX-Mex) that was carried out in collaboration with the Megacity Interactions: Local and Global Research Observations (MILAGRO) campaign. MILAGRO was a joint effort between the DOE, NSF, NASA, and Mexican agencies aimed at understanding the impacts of a megacity on the urban and regional scale. A super-site was operated at the Instituto Mexicano de Petroleo in Mexico City (designated T-0) and at the Universidad Technologica de Tecamac (designated T-1) that was located about 35 km to the north east of the T-0 site in the State of Mexico. A third site was located at a private rancho in the State of Hidalgo approximately another 35 km to the northeast (designated T-2). Aerosol absorption measurements were taken in real time using a number of instruments at the T-0 and T-1 sites. These included a seven wavelength aethalometer, a multi-angle absorption photometer (MAAP), and a photo-acoustic spectrometer. Aerosol absorption was also derived from spectral radiometers including a multi-filter rotating band spectral radiometer (MFRSR). The results clearly indicate that there is significant aerosol absorption by the aerosols in the Mexico City megacity region. The absorption can lead to single scattering albedo reduction leading to values below 0.5 under some circumstances. The absorption is also found to deviate from that expected for a "well-behaved" soot anticipated from diesel engine emissions, i.e. from a simple 1/lambda wavelength dependence for absorption. Indeed, enhanced absorption is seen in the region of 300-450 nm in many cases, particularly in the afternoon periods indicating that secondary organic aerosols are contributing to the aerosol absorption. This is likely due

  14. Light absorption of organic aerosol from pyrolysis of corn stalk

    NASA Astrophysics Data System (ADS)

    Li, Xinghua; Chen, Yanju; Bond, Tami C.

    2016-11-01

    Organic aerosol (OA) can absorb solar radiation in the low-visible and ultra-violet wavelengths thereby modifying radiative forcing. Agricultural waste burning emits a large quantity of organic carbon in many developing countries. In this work, we improved the extraction and analysis method developed by Chen and Bond, and extended the spectral range of OC absorption. We examined light absorbing properties of primary OA from pyrolysis of corn stalk, which is a major type of agricultural wastes. Light absorption of bulk liquid extracts of OA was measured using a UV-vis recording spectrophotometer. OA can be extracted by methanol at 95%, close to full extent, and shows polar character. Light absorption of organic aerosol has strong spectral dependence (Absorption Ångström exponent = 7.7) and is not negligible at ultra-violet and low-visible regions. Higher pyrolysis temperature produced OA with higher absorption. Imaginary refractive index of organic aerosol (kOA) is 0.041 at 400 nm wavelength and 0.005 at 550 nm wavelength, respectively.

  15. Measurements and Modeling of Aerosol Absorption and Single Scattering Albedo at Ambient Relative Hum

    NASA Technical Reports Server (NTRS)

    Redemann, J.; Russell, P. B.; Hamill, P.

    2000-01-01

    Uncertainties in the aerosol single scattering albedo have been identified to be an important source of errors in current large-scale model estimates of the direct aerosol radiative forcing of climate. A number of investigators have obtained estimates of the single scattering albedo from a variety of remote sensing and in situ measurements during aerosol field experiments. During the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX, 1996) for example, estimates of the aerosol single scattering albedo were obtained (1) as a best-fit parameter in comparing radiative flux changes measured by airborne pyranometer to those computed from independently measured aerosol properties; (2) from estimates of the aerosol complex index of refraction derived using a combination of airborne sunphotometer, lidar backscatter and in situ size distribution measurements; and (3) from airborne measurements of aerosol scattering and absorption using nephelometers and absorption photometers. In this paper, we briefly compare the results of the latter two methods for two TARFOX case studies, since those techniques provide height-resolved information about the aerosol single scattering albedo. Estimates of the aerosol single scattering albedo from nephelometer and absorption photometer measurements require knowledge of the scattering and absorption humidification (i.e., the increase in these properties in response to an increase in ambient relative humidity), since both measurements are usually carried out at a relative humidity different from the ambient atmosphere. In principle, the scattering humidification factor can be measured, but there is currently no technique widely available to measure the absorption of an aerosol sample as a function of relative humidity. Frequently, for lack of better knowledge, the absorption humidification is assumed to be unity (meaning that there is no change in aerosol absorption due to an increase in ambient relative humidity). This

  16. Cost Index Flying

    DTIC Science & Technology

    2011-06-01

    continually alter applicable cost indexes . Computed KC-10 Cost Index Equation Using the dollar figures given above, our CI equation reads : CI = CT / C...COST INDEX FLYING GRADUATE RESEARCH PAPER John M. Mirtich, Major, USAF AFIT/IMO/ENS/11-11 DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY...AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base, Ohio APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

  17. Inversion Techniques for Retrieving Detailed Aerosol Properties from Remote Sensing Observations: Achievements and Perspectives

    NASA Astrophysics Data System (ADS)

    Dubovik, O.

    2010-12-01

    applications. Specifically, the retrieval of detailed information about aerosol particle sizes, shape, absorption and composition (refractive index) from the observations by sun/sky-scanning radiometers has been developed and employed by worldwide AERONET network of ground-based radiometers. One of first retrievals of global aerosol emission sources from MODIS satellite observations have been suggested and realized using the same concept. Finally, the most recent results show a high potential of applying the methodology for deriving aerosol properties over bright land surfaces from POLDER multi-angle spectral polarimetric satellite observations using a new approach of simultaneous inversion of large groups of satellite pixels.

  18. The dimensions of indexing.

    PubMed

    Wilbur, W John; Kim, Won

    2003-01-01

    Indexing of documents is an important strategy intended to make the literature more readily available to the user. Here we describe several dimensions of indexing that are important if indexing is to be optimal. These dimensions are coverage, predictability, and transparency. MeSH terms and text words are compared in MEDLINE in regard to these dimensions. Part of our analysis consists in applying AdaBoost with decisions trees as the weak learners to estimate how reliably index terms are being assigned and how complex the criteria are by which they are being assigned. Our conclusions are that MeSH terms are more predictable and more transparent than text words.

  19. Aerosol and monsoon climate interactions over Asia

    NASA Astrophysics Data System (ADS)

    Li, Zhanqing; Lau, W. K.-M.; Ramanathan, V.; Wu, G.; Ding, Y.; Manoj, M. G.; Liu, J.; Qian, Y.; Li, J.; Zhou, T.; Fan, J.; Rosenfeld, D.; Ming, Y.; Wang, Y.; Huang, J.; Wang, B.; Xu, X.; Lee, S.-S.; Cribb, M.; Zhang, F.; Yang, X.; Zhao, C.; Takemura, T.; Wang, K.; Xia, X.; Yin, Y.; Zhang, H.; Guo, J.; Zhai, P. M.; Sugimoto, N.; Babu, S. S.; Brasseur, G. P.

    2016-12-01

    The increasing severity of droughts/floods and worsening air quality from increasing aerosols in Asia monsoon regions are the two gravest threats facing over 60% of the world population living in Asian monsoon regions. These dual threats have fueled a large body of research in the last decade on the roles of aerosols in impacting Asian monsoon weather and climate. This paper provides a comprehensive review of studies on Asian aerosols, monsoons, and their interactions. The Asian monsoon region is a primary source of emissions of diverse species of aerosols from both anthropogenic and natural origins. The distributions of aerosol loading are strongly influenced by distinct weather and climatic regimes, which are, in turn, modulated by aerosol effects. On a continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulations. The atmospheric thermodynamic state, which determines the formation of clouds, convection, and precipitation, may also be altered by aerosols serving as cloud condensation nuclei or ice nuclei. Absorbing aerosols such as black carbon and desert dust in Asian monsoon regions may also induce dynamical feedback processes, leading to a strengthening of the early monsoon and affecting the subsequent evolution of the monsoon. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of different monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from

  20. Biology of the Coarse Aerosol Mode: Insights Into Urban Aerosol Ecology

    NASA Astrophysics Data System (ADS)

    Dueker, E.; O'Mullan, G. D.; Montero, A.

    2015-12-01

    Microbial aerosols have been understudied, despite implications for climate studies, public health, and biogeochemical cycling. Because viable bacterial aerosols are often associated with coarse aerosol particles, our limited understanding of the coarse aerosol mode further impedes our ability to develop models of viable bacterial aerosol production, transport, and fate in the outdoor environment, particularly in crowded urban centers. To address this knowledge gap, we studied aerosol particle biology and size distributions in a broad range of urban and rural settings. Our previously published findings suggest a link between microbial viability and local production of coarse aerosols from waterways, waste treatment facilities, and terrestrial systems in urban and rural environments. Both in coastal Maine and in New York Harbor, coarse aerosols and viable bacterial aerosols increased with increasing wind speeds above 4 m s-1, a dynamic that was observed over time scales ranging from minutes to hours. At a New York City superfund-designated waterway regularly contaminated with raw sewage, aeration remediation efforts resulted in significant increases of coarse aerosols and bacterial aerosols above that waterway. Our current research indicates that bacterial communities in aerosols at this superfund site have a greater similarity to bacterial communities in the contaminated waterway with wind speeds above 4 m s-1. Size-fractionated sampling of viable microbial aerosols along the urban waterfront has also revealed significant shifts in bacterial aerosols, and specifically bacteria associated with coarse aerosols, when wind direction changes from onshore to offshore. This research highlights the key connections between bacterial aerosol viability and the coarse aerosol fraction, which is important in assessments of production, transport, and fate of bacterial contamination in the urban environment.

  1. Toxicity of atmospheric aerosols on marine phytoplankton

    PubMed Central

    Paytan, Adina; Mackey, Katherine R. M.; Chen, Ying; Lima, Ivan D.; Doney, Scott C.; Mahowald, Natalie; Labiosa, Rochelle; Post, Anton F.

    2009-01-01

    Atmospheric aerosol deposition is an important source of nutrients and trace metals to the open ocean that can enhance ocean productivity and carbon sequestration and thus influence atmospheric carbon dioxide concentrations and climate. Using aerosol samples from different back trajectories in incubation experiments with natural communities, we demonstrate that the response of phytoplankton growth to aerosol additions depends on specific components in aerosols and differs across phytoplankton species. Aerosol additions enhanced growth by releasing nitrogen and phosphorus, but not all aerosols stimulated growth. Toxic effects were observed with some aerosols, where the toxicity affected picoeukaryotes and Synechococcus but not Prochlorococcus. We suggest that the toxicity could be due to high copper concentrations in these aerosols and support this by laboratory copper toxicity tests preformed with Synechococcus cultures. However, it is possible that other elements present in the aerosols or unknown synergistic effects between these elements could have also contributed to the toxic effect. Anthropogenic emissions are increasing atmospheric copper deposition sharply, and based on coupled atmosphere–ocean calculations, we show that this deposition can potentially alter patterns of marine primary production and community structure in high aerosol, low chlorophyll areas, particularly in the Bay of Bengal and downwind of South and East Asia. PMID:19273845

  2. Toxicity of atmospheric aerosols on marine phytoplankton

    USGS Publications Warehouse

    Paytan, A.; Mackey, K.R.M.; Chen, Y.; Lima, I.D.; Doney, S.C.; Mahowald, N.; Labiosa, R.; Post, A.F.

    2009-01-01

    Atmospheric aerosol deposition is an important source of nutrients and trace metals to the open ocean that can enhance ocean productivity and carbon sequestration and thus influence atmospheric carbon dioxide concentrations and climate. Using aerosol samples from different back trajectories in incubation experiments with natural communities, we demonstrate that the response of phytoplankton growth to aerosol additions depends on specific components in aerosols and differs across phytoplankton species. Aerosol additions enhanced growth by releasing nitrogen and phosphorus, but not all aerosols stimulated growth. Toxic effects were observed with some aerosols, where the toxicity affected picoeukaryotes and Synechococcus but not Prochlorococcus.We suggest that the toxicity could be due to high copper concentrations in these aerosols and support this by laboratory copper toxicity tests preformed with Synechococcus cultures. However, it is possible that other elements present in the aerosols or unknown synergistic effects between these elements could have also contributed to the toxic effect. Anthropogenic emissions are increasing atmospheric copper deposition sharply, and based on coupled atmosphere-ocean calculations, we show that this deposition can potentially alter patterns of marine primary production and community structure in high aerosol, low chlorophyll areas, particularly in the Bay of Bengal and downwind of South and East Asia.

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

    PubMed Central

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

    2009-01-01

    Red tide aerosols containing aerosolized brevetoxins are produced during the red tide bloom and transported by wind to coastal areas of Florida. This study reports the characterization of Florida red tide aerosols in human volunteer studies, in which an asthma cohort spent 1 h on Siesta Beach (Sarasota, Florida) during aerosolized red tide events and non-exposure periods. Aerosol concentrations, brevetoxin levels, and particle size distribution were measured. Hourly filter samples were taken and analyzed for brevetoxin and NaCl concentrations. In addition, the aerosol mass concentration was monitored in real time. The results indicated that during a non-exposure period in October 2004, no brevetoxin was detected in the water, resulting in non-detectable levels of brevetoxin in the aerosol. In March 2005, the time-averaged concentrations of brevetoxins in water samples were moderate, in the range of 5–10 μg/L, and the corresponding brevetoxin level of Florida red tide aerosol ranged between 21 and 39 ng/m3. The temporal profiles of red tide aerosol concentration in terms of mass, NaCl, and brevetoxin were in good agreement, indicating that NaCl and brevetoxins are components of the red tide aerosol. By continuously monitoring the marine aerosol and wind direction at Siesta Beach, we observed that the marine aerosol concentration varied as the wind direction changed. The temporal profile of the Florida red tide aerosol during a sampling period could be explained generally with the variation of wind direction. PMID:19879288

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

    PubMed

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

    2010-05-01

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

  5. Reformulating Aerosol Thermodynamics and Cloud Microphysics

    NASA Astrophysics Data System (ADS)

    Metzger, S.

    2006-12-01

    Modeling aerosol composition and cloud microphysics is rather complex due to the required thermodynamics, even if chemical and thermodynamical equilibrium is assumed. We show, however, that for deliquescent atmospheric aerosols thermodynamics can be considerably simplified, if we reformulate chemical equilibrium to include water purely based on thermodynamic principles. In chemical and thermodynamical equilibrium, the relative humidity (RH) fixes the molality of atmospheric aerosols. Although this fact is in theory well known, it has hardly been utilized in aerosol modeling nor has been the fact that for the same reason also the aerosol activity (including activity coefficients) and water content are fixed (by RH) for a given aerosol concentration and type. The only model that successfully utilizes this fact is the computationally very efficient EQuilibrium Simplified thermodynamic gas/Aerosol partitioning Model, EQSAM (Metzger et al., 2002a), EQSAM2 (Metzger et al., 2006). In both versions the entire gas/liquid/solid aerosol equilibrium partitioning is solved analytically and hence non-iteratively a substantial advantage in aerosol composition modeling. Here we briefly present the theoretical framework of EQSAM2, which differs from EQSAM in a way that the calculation of the water activity of saturated binary or mixed inorganic/organic salt solutions of multi-component aerosols has been generalized by including the Kelvin-term, thus allowing for any solute activity above the deliquescence relative humidity, including supersaturation. With application of our new concept to a numerical whether prediction (NWP) model, we demonstrate its wide implications for the computation of various aerosol and cloud properties, as our new concept allows to consistently and efficiently link the modeling of aerosol thermodynamics and cloud microphysics through the aerosol water mass, which therefore deserves special attention in atmospheric chemistry, air pollution, NWP and climate

  6. Optical properties and cross-sections of biological aerosols

    NASA Astrophysics Data System (ADS)

    Thrush, E.; Brown, D. M.; Salciccioli, N.; Gomes, J.; Brown, A.; Siegrist, K.; Thomas, M. E.; Boggs, N. T.; Carter, C. C.

    2010-04-01

    There is an urgent need to develop standoff sensing of biological agents in aerosolized clouds. In support of the Joint Biological Standoff Detection System (JBSDS) program, lidar systems have been a dominant technology and have shown significant capability in field tests conducted in the Joint Ambient Breeze Tunnel (JABT) at Dugway Proving Ground (DPG). The release of biological agents in the open air is forbidden. Therefore, indirect methods must be developed to determine agent cross-sections in order to validate sensor against biological agents. A method has been developed that begins with laboratory measurements of thin films and liquid suspensions of biological material to obtain the complex index of refraction from the ultraviolet (UV) to the long wave infrared (LWIR). Using that result and the aerosols' particle size distribution as inputs to Mie calculations yields the backscatter and extinction cross-sections as a function of wavelength. Recent efforts to model field measurements from the UV to the IR have been successful. Measurements with aerodynamic and geometric particle sizers show evidence of particle clustering. Backscatter simulations of these aerosols show these clustered particles dominate the aerosol backscatter and depolarization signals. In addition, these large particles create spectral signatures in the backscatter signal due to material absorption. Spectral signatures from the UV to the IR have been observed in simulations of field releases. This method has been demonstrated for a variety of biological simulant materials such as Ovalbumin (OV), Erwinia (EH), Bacillus atrophaeus (BG) and male specific bacteriophage (MS2). These spectral signatures may offer new methods for biological discrimination for both stand-off sensing and point detection systems.

  7. A study of the aerosol radiative properties needed to compute direct aerosol forcing in the southeastern United States

    NASA Astrophysics Data System (ADS)

    Yu, Shaocai; Saxena, V. K.; Wenny, B. N.; Deluisi, J. J.; Yue, G. K.; Petropavlovskikh, I. V.

    2000-10-01

    To assess the direct radiative forcing due to aerosols in southeastern United States where a mild cooling is under way, an accurate set of data describing the aerosol radiative properties are needed. We report here aerosol optical depth (AOD) and diffuse to-direct solar irradiance ratio (DDR) at three operational wavelengths (415, 500, 673 nm) determined by using Multifilter Rotating Shadowband Radiometers (MFRSR) at two sites (a mountain top site: Mount Gibbes, 35.78°N, 82.29°W, 2006 m mean sea level (msl); a valley site: Black Mountain, 35.66°N, 82.38°W, 951 m msl), which are separated horizontally by 10 km and vertically by 1 km. The characteristics AOD and DDR were determined from the field measurements obtained during 1995. It was found that the representative total AOD values at 500 nm at the valley site for highly polluted (HP), marine (M) and continental (C) air masses were 0.68±0.33, 0.29±0.19, and 0.10±0.04, respectively. The fact that the ratio of the mean 1 km layer optical depth to total mean optical depth at 500 nm from the valley site was 71% indicates that the major portion of the atmospheric aerosol was located in the lowest 1 km surface boundary layer (SBL). There was a significant linear correlation between the DDR and the total AOD at both sites. A simple, fast, and operative search-graph method was used to retrieve the columnar size distribution (number concentration N effective radius reff, and geometric standard deviation σg) from the optical depth observations at the three operational wavelengths. The ground albedo, single-scattering albedo, and imaginary part of the refractive index are calculated using a mathematically unique procedure involving a Mie code and a radiative transfer code in conjunction with the retrieved aerosol size distribution, AOD, and DDR. It was found that N, reff, and σg were in the range of 1.9×10 to 1.7×104 cm-3, 0.09-0.68 μm, and 1.12-2.70, respectively. The asymmetry factor and single-scattering albedo

  8. Marine Aerosols: Hygroscopocity and Aerosol-Cloud Relationships

    DTIC Science & Technology

    2012-09-30

    MSc) clouds. A CIRPAS Twin Otter field experiment took place in July-August 2011 over the eastern Pacific Ocean off the coast of Monterey, CA...large eddy simulation (LES) and field measurements, the latter including Twin Otter missions such as MASE I and MASE II and those involving other...properties in ship tracks, which have continued to serve as a well-defined example of marine aerosol-cloud perturbations. The Twin Otter payload has

  9. Aerosol Retrievals over the Ocean using Channel 1 and 2 AVHRR Data: A Sensitivity Analysis and Preliminary Results

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Geogdzhayev, Igor V.; Cairns, Brian; Rossow, William B.; Lacis, Andrew A.

    1999-01-01

    This paper outlines the methodology of interpreting channel 1 and 2 AVHRR radiance data over the oceans and describes a detailed analysis of the sensitivity of monthly averages of retrieved aerosol parameters to the assumptions made in different retrieval algorithms. The analysis is based on using real AVHRR data and exploiting accurate numerical techniques for computing single and multiple scattering and spectral absorption of light in the vertically inhomogeneous atmosphere-ocean system. We show that two-channel algorithms can be expected to provide significantly more accurate and less biased retrievals of the aerosol optical thickness than one-channel algorithms and that imperfect cloud screening and calibration uncertainties are by far the largest sources of errors in the retrieved aerosol parameters. Both underestimating and overestimating aerosol absorption as well as the potentially strong variability of the real part of the aerosol refractive index may lead to regional and/or seasonal biases in optical thickness retrievals. The Angstrom exponent appears to be the most invariant aerosol size characteristic and should be retrieved along with optical thickness as the second aerosol parameter.

  10. Potential modulations of pre-monsoon aerosols during El Niño: impact on Indian summer monsoon

    NASA Astrophysics Data System (ADS)

    Fadnavis, S.; Roy, Chaitri; Sabin, T. P.; Ayantika, D. C.; Ashok, K.

    2016-11-01

    The potential role of aerosol loading on the Indian summer monsoon rainfall during the El Niño years are examined using satellite-derived observations and a state of the art fully interactive aerosol-chemistry-climate model. The Aerosol Index (AI) from TOMS (1978-2005) and Aerosol Optical Depth (AOD) from MISR spectroradiometer (2000-2010) indicate a higher-than-normal aerosol loading over the Indo-Gangetic plain (IGP) during the pre-monsoon season with a concurrent El Niño. Sensitivity experiments using ECHAM5-HAMMOZ climate model suggests that this enhanced loading of pre-monsoon absorbing aerosols over the Indo-Gangetic plain can reduce the drought during El Niño years by invoking the `Elevated-Heat-Pump' mechanism through an anomalous aerosol-induced warm core in the atmospheric column. This anomalous heating upshot the relative strengthening of the cross-equatorial moisture inflow associated with the monsoon and eventually reduces the severity of drought during El Niño years. The findings are subject to the usual limitations such as the uncertainties in observations, and limited number of El Niño years (during the study period).

  11. 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

  12. Light absorption, optical and microphysical properties of trajectory-clustered aerosols at two AERONET sites in West Africa

    NASA Astrophysics Data System (ADS)

    Fawole, O. G.; Cai, X.; MacKenzie, A. R.

    2015-12-01

    Aerosol remote sensing techniques and back-trajectory modeling can be combined to identify aerosol types. We have clustered 7 years of AERONET aerosol signals using trajectory analysis to identify dominant aerosol sources at two AERONET sites in West Africa: Ilorin (4.34 oE, 8.32 oN) and Djougou (1.60 oE, 9.76 oN). Of particular interest are air masses that have passed through the gas flaring region in the Niger Delta area, of Nigeria, en-route the AERONET sites. 7-day back trajectories were calculated using the UK UGAMP trajectory model driven by ECMWF wind analyses data. Dominant sources identified, using literature classifications, are desert dust (DD), Biomass burning (BB) and Urban-Industrial (UI). Below, we use a combination of synoptic trajectories and aerosol optical properties to distinguish a fourth source: that due to gas flaring. Gas flaring, (GF) the disposal of gas through stack in an open-air flame, is believed to be a prominent source of black carbon (BC) and greenhouse gases. For these different aerosol source signatures, single scattering albedo (SSA), refractive index , extinction Angstrom exponent (EEA) and absorption Angstrom exponent (AAE) were used to classify the light absorption characteristics of the aerosols for λ = 440, 675, 870 and1020 nm. A total of 1625 daily averages of aerosol data were collected for the two sites. Of which 245 make up the GF cluster for both sites. For GF cluster, the range of fine-mode fraction is 0.4 - 0.7. Average values SSA(λ), for the total and GF clusters are 0.90(440), 0.93(675), 0.95(870) and 0.96(1020), and 0.93(440), 0.92(675), 0.9(870) and 0.9(1020), respectively. Values of for the GF clusters for both sites are 0.62 - 1.11, compared to 1.28 - 1.66 for the remainder of the clusters, which strongly indicates the dominance of carbonaceous particles (BC), typical of a highly industrial area. An average value of 1.58 for the real part of the refractive index at low SSA for aerosol in the GF cluster is also

  13. Volcanic loading: The dust veil index

    SciTech Connect

    Lamb, H.H.

    1985-09-01

    Dust ejected into the high atmosphere during explosive volcanic eruptions has been considered as a possible cause for climatic change. Dust veils created by volcanic eruptions can reduce the amount of light reaching the Earth`s surface and can cause reductions in surface temperatures. These climatic effects can be seen for several years following some eruptions and the magnitude and duration of the effects depend largely on the density or amount of tephra (i.e. dust) ejected, the latitude of injection, and atmospheric circulation patterns. Lamb (1970) formulated the Dust Veil Index (DVI) in an attempt to quantify the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact on the Earth`s energy balance of changes in atmospheric composition due to explosive volcanic eruptions. The DVI is a numerical index that quantifies the impact of a particular volcanic eruptions release of dust and aerosols over the years following the event. The DVI for any volcanic eruptions are available and have been used in estimating Lamb`s dust veil indices.

  14. Ultraviolet Index measurements in Southern Bahia, Brazil

    NASA Astrophysics Data System (ADS)

    de Paula Corrêa, Marcelo; Morégula, Andréa; Fausto, Agnes; Okuno, Emico; Mol, Anderson; Santos, João C.

    2009-03-01

    This work presents results of the Joint Project for Solar UV Index Measurements in Southern Bahia State (PIU Project), and represents the first effort to measure UV radiation in this tourist region. The project goal is twofold: it has a scientific component in which the distribution of UV Index will be mapped out, and it also intends to disseminate the data as a mean of divulgation of the UV Index levels to the population. This constitutes a meaningful effort to reduce health risks from excessive solar radiation exposure in a country that reports more than 120,000 new skin cancer cases each year. This project is within the framework of a larger initiative to studying UV index distribution in Brazilian regions. PIU project has had two phases: 1) seasonal measurements were performed during the summer and winter seasons of 2006 and 2007 on a sandy beach in Ilhéus (15,0° S; 39,0° W; sea level), as well as on an asphalt surface in the urban perimeter of Itabuna (14,8° S; 39,3° W; 54 m ASL); and 2) since October 2007, measurements have been continuously conducted on a concrete surface, about 20 km from the beach, in a urban area of Ilhéus. During the summer season, UV Index reaches extreme values (>11), and in winter, results range between high (6aerosol optical depth will be retrieved from MODIS sensors (Aqua and Terra satellites) and UV theoretical calculations should be used to quantify the radiation attenuation.

  15. Indexing for Invention.

    ERIC Educational Resources Information Center

    Breton, Ernest J.

    1991-01-01

    Describes the development of a functional indexing system that is tailored to the thinking involved in the process of invention. Classification by function is discussed; matrix representation is explained; a controlled vocabulary of verbs, objects, and modifiers is described; and the relation to other indexing systems is examined. (13 references)…

  16. Indexing Editorial Cartoons.

    ERIC Educational Resources Information Center

    Chapple-Sokol, Angie

    1996-01-01

    Discusses access to editorial cartoons, including the importance and worth of editorial cartoons; sources, including newspapers, museums, and special cartoon collections; indexing and classification; subject access; indexing by illustrator and subject; technology and access, including digital data; access to special collections; and access to…

  17. Linked Phrase Indexing.

    ERIC Educational Resources Information Center

    Craven, Timothy C.

    1978-01-01

    Describes a computer-assisted system for the production of printed indexes based on networks of concept relations expressed in natural-language-like form. The LIPHIS is designed to handle more complex networks of concept relations, and so produce better indexing of highly detailed subjects. (Author/CWM)

  18. EMMSE Media Index.

    ERIC Educational Resources Information Center

    Hewitt, Clifford A., Comp.; McKinstry, Herbert A., Comp.

    This index provides a topical taxonomy of media which have been selected for their relevance in the teaching of materials science and engineering. The index is keyed to a matrix which matches topical and/or class material with six classifications of media: print, 16mm film, super 8 film, slide/tape, videotape, and other (including interactive…

  19. A Computer Calculated Index.

    ERIC Educational Resources Information Center

    Brown, Francis J.

    The Gunning Fog Index of readability indicates both the average length of words and the difficult words (three or more syllables) in written material. This document describes a business communication course at Wayne State University in which students calculate the Gunning Fog Index of two of their writing assignments with the aid of the…

  20. Transfer Index: One Definition.

    ERIC Educational Resources Information Center

    Heinselman, James L.

    A transfer index of the proportion of students in California's community colleges transferring to the University of California (UC) and the California State University (CSU) system for fall 1982, 1983, and 1984 is presented in this report. Introductory material provides one definition of an appropriate index of transfer rates, i.e., the ratio of…

  1. Universal Index System

    NASA Technical Reports Server (NTRS)

    Kelley, Steve; Roussopoulos, Nick; Sellis, Timos; Wallace, Sarah

    1993-01-01

    The Universal Index System (UIS) is an index management system that uses a uniform interface to solve the heterogeneity problem among database management systems. UIS provides an easy-to-use common interface to access all underlying data, but also allows different underlying database management systems, storage representations, and access methods.

  2. Children's Stress Index.

    ERIC Educational Resources Information Center

    Sherman, Dianne, Ed.

    1993-01-01

    This double issue of the "ZPG Reporter" focuses on the theme of ZPG's Children's Stress Index", the first national survey of children's well-being based on population- related pressures. Using an extensive list of social, economic, and environmental factors that affect the lives of children, the index ranks 828 cities, counties, and…

  3. A Factor Simplicity Index.

    ERIC Educational Resources Information Center

    Lorenzo-Seva, Urbano

    2003-01-01

    Proposes an index for assessing the degree of factor simplicity in the context of principal components and exploratory factor analysis. The index does not depend on the scale of the factors, and its maximum and minimum are related only to the degree of simplicity in the loading matrix. (SLD)

  4. Gradient index retroreflector

    DOEpatents

    Layne, Clyde B.

    1988-01-01

    A retroreflector is formed of a graded index lens with a reflective coating at one end. The lens has a length of an odd multiple of a quarter period thereof. Hexagonally shaped graded index lenses may be closely packed in an array to form a retroreflecting surface.

  5. CCN activity of aliphatic amine secondary aerosol

    NASA Astrophysics Data System (ADS)

    Tang, X.; Price, D.; Praske, E.; Vu, D.; Purvis-Roberts, K.; Silva, P. J.; Cocker, D. R., III; Asa-Awuku, A.

    2014-01-01

    Aliphatic amines can form secondary aerosol via oxidation with atmospheric radicals (e.g. hydroxyl radical and nitrate radical). The particle composition can contain both secondary organic aerosol (SOA) and inorganic salts. The fraction of organic to inorganic materials in the particulate phase influences aerosol hygroscopicity and cloud condensation nuclei (CCN) activity. SOA formed from trimethylamine (TMA) and butylamine (BA) reactions with hydroxyl radical (OH) is composed of organic material of low hygroscopicity (single hygroscopicity parameter, κ ≤ 0.25). Secondary aerosol formed from the tertiary aliphatic amine (TMA) with N2O5 (source of nitrate radical, NO3), contains less volatile compounds than the primary aliphatic amine (BA) aerosol. TMA + N2O5 form semi-volatile organics in low RH conditions that have κ ~ 0.20, indicative of slightly soluble organic material. As RH increases, several inorganic amine salts are formed as a result of acid-base reactions. The CCN activity of the humid TMA-N2O5 aerosol obeys Zdanovskii, Stokes, and Robinson (ZSR) ideal mixing rules. Higher CCN activity (κ > 0.3) was also observed for humid BA+N2O5 aerosols compared with dry aerosol (κ ~ 0.2), as a result of the formation of inorganic salts such as NH4NO3 and butylamine nitrate (C4H11N · HNO3). Compared with TMA, BA+N2O5 reactions produce more volatile aerosols. The BA+N2O5 aerosol products under humid experiments were found to be very sensitive to the temperature within the stream-wise continuous flow thermal gradient CCN counter. The CCN counter, when set above a 21 °C temperature difference, evaporates BA+N2O5 aerosol formed at RH ≥ 30%; κ ranges from 0.4 to 0.7 and is dependent on the instrument supersaturation (ss) settings. The aerosol behaves non-ideally, hence simple ZSR rules cannot be applied to the CCN results from the primary aliphatic amine system. Overall, aliphatic amine aerosol systems κ ranges from 0.2 < κ < 0.7. This work indicates that

  6. How We Can Constrain Aerosol Type Globally

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph

    2016-01-01

    In addition to aerosol number concentration, aerosol size and composition are essential attributes needed to adequately represent aerosol-cloud interactions (ACI) in models. As the nature of ACI varies enormously with environmental conditions, global-scale constraints on particle properties are indicated. And although advanced satellite remote-sensing instruments can provide categorical aerosol-type classification globally, detailed particle microphysical properties are unobtainable from space with currently available or planned technologies. For the foreseeable future, only in situ measurements can constrain particle properties at the level-of-detail required for ACI, as well as to reduce uncertainties in regional-to-global-scale direct aerosol radiative forcing (DARF). The limitation of in situ measurements for this application is sampling. However, there is a simplifying factor: for a given aerosol source, in a given season, particle microphysical properties tend to be repeatable, even if the amount varies from day-to-day and year-to-year, because the physical nature of the particles is determined primarily by the regional environment. So, if the PDFs of particle properties from major aerosol sources can be adequately characterized, they can be used to add the missing microphysical detail the better sampled satellite aerosol-type maps. This calls for Systematic Aircraft Measurements to Characterize Aerosol Air Masses (SAM-CAAM). We are defining a relatively modest and readily deployable, operational aircraft payload capable of measuring key aerosol absorption, scattering, and chemical properties in situ, and a program for characterizing statistically these properties for the major aerosol air mass types, at a level-of-detail unobtainable from space. It is aimed at: (1) enhancing satellite aerosol-type retrieval products with better aerosol climatology assumptions, and (2) improving the translation between satellite-retrieved aerosol optical properties and

  7. Comparing MODIS C6 'Deep Blue' and 'Dark Target' Aerosol Data

    NASA Technical Reports Server (NTRS)

    Hsu, N. C.; Sayer, A. M.; Bettenhausen, C.; Lee, J.; Levy, R. C.; Mattoo, S.; Munchak, L. A.; Kleidman, R.

    2014-01-01

    The MODIS Collection 6 Atmospheres product suite includes refined versions of both 'Deep Blue' (DB) and 'Dark Target' (DT) aerosol algorithms, with the DB dataset now expanded to include coverage over vegetated land surfaces. This means that, over much of the global land surface, users will have both DB and DT data to choose from. A 'merged' dataset is also provided, primarily for visualization purposes, which takes retrievals from either or both algorithms based on regional and seasonal climatologies of normalized difference vegetation index (NDVI). This poster present some comparisons of these two C6 aerosol algorithms, focusing on AOD at 550 nm derived from MODIS Aqua measurements, with each other and with Aerosol Robotic Network (AERONET) data, with the intent to facilitate user decisions about the suitability of the two datasets for their desired applications.

  8. Characterization of tropospheric desert aerosols at solar wavelengths by multispectral radiometry from Landsat

    USGS Publications Warehouse

    Otterman, Joseph; Fraser, R. S.; Bahethi, O. P.

    1982-01-01

    Characteristics of tropospheric desert aerosols are derived by comparing nadir spectral reflectivities computed from the radiative transfer models with reflectivities measured from Landsat. Over the ocean, reflectivities are compared, but over land the comparison is carried out by determining the ratios of the nadir reflectivity of the surface-atmosphere system over heavy aerosol concentration to the reflectivity of the underlying surface. This remote sensing technique is found to be a sensitive approach for measuring n2, the imaginary part of the refractive index. The desert aerosols under study, in the Iran and Pakistan area, are essentially pure scatterers, inasmuch as an n2 value of 0.001±0.001 was determined for each of the four Landsat spectral bands, that is, for a spectral interval from 0.5 to 1.1 μm.

  9. Radiative forcing by stratospheric aerosol in a CCM with interactive aerosol module

    NASA Astrophysics Data System (ADS)

    Brühl, Christoph; Lelieveld, Jos; Tost, Holger; Steil, Benedikt; Höpfner, Michael

    2013-04-01

    Multiyear studies with the atmospheric chemistry general circulation model EMAC with the aerosol module GMXe demonstrate that stratospheric aerosol formation is controlled by COS oxidation and SO2 injected by low-latitude volcanic eruptions. The model consistently uses the same parameters in the troposphere and stratosphere for 7 aerosol modes applied. Calculated radiative heating by aerosol feeds back to stratospheric dynamics. Radiative forcing by stratospheric aerosol can be diagnosed separately. The simulations include the medium size tropical eruptions in 2003, 2005 and 2006 but also the major eruption of Pinatubo in 1991. We show that calculated radiative forcing by stratospheric aerosol agrees well with the corresponding satellite derived quantity and that the medium size tropical eruptions should not be neglected in climate simulations. Changes in temperature, dynamics and tracer transport due to interactive aerosol will be also presented. We show also that calculated aerosol and SO2 concentrations are consistent with the observations by SAGE and by MIPAS on ENVISAT.

  10. On the implications of aerosol liquid water and phase separation for organic aerosol mass

    EPA Science Inventory

    Organic compounds and liquid water are major aerosol constituents in the southeast United States (SE US). Water associated with inorganic constituents (inorganic water) can contribute to the partitioning medium for organic aerosol when relative humidities or organic matter to org...

  11. Validation of MODIS Aerosol Retrieval Over Ocean

    NASA Technical Reports Server (NTRS)

    Remer, Lorraine A.; Tanre, Didier; Kaufman, Yoram J.; Ichoku, Charles; Mattoo, Shana; Levy, Robert; Chu, D. Allen; Holben, Brent N.; Dubovik, Oleg; Ahmad, Ziauddin; Einaudi, Franco (Technical Monitor)

    2001-01-01

    The MODerate resolution Imaging Spectroradiometer (MODIS) algorithm for determining aerosol characteristics over ocean is performing with remarkable accuracy. A two-month data set of MODIS retrievals co-located with observations from the AErosol RObotic NETwork (AERONET) ground-based sunphotometer network provides the necessary validation. Spectral radiation measured by MODIS (in the range 550 - 2100 nm) is used to retrieve the aerosol optical thickness, effective particle radius and ratio between the submicron and micron size particles. MODIS-retrieved aerosol optical thickness at 660 nm and 870 nm fall within the expected uncertainty, with the ensemble average at 660 nm differing by only 2% from the AERONET observations and having virtually no offset. MODIS retrievals of aerosol effective radius agree with AERONET retrievals to within +/- 0.10 micrometers, while MODIS-derived ratios between large and small mode aerosol show definite correlation with ratios derived from AERONET data.

  12. Aerosol Modeling for the Global Model Initiative

    NASA Technical Reports Server (NTRS)

    Weisenstein, Debra K.; Ko, Malcolm K. W.

    2001-01-01

    The goal of this project is to develop an aerosol module to be used within the framework of the Global Modeling Initiative (GMI). The model development work will be preformed jointly by the University of Michigan and AER, using existing aerosol models at the two institutions as starting points. The GMI aerosol model will be tested, evaluated against observations, and then applied to assessment of the effects of aircraft sulfur emissions as needed by the NASA Subsonic Assessment in 2001. The work includes the following tasks: 1. Implementation of the sulfur cycle within GMI, including sources, sinks, and aqueous conversion of sulfur. Aerosol modules will be added as they are developed and the GMI schedule permits. 2. Addition of aerosol types other than sulfate particles, including dust, soot, organic carbon, and black carbon. 3. Development of new and more efficient parameterizations for treating sulfate aerosol nucleation, condensation, and coagulation among different particle sizes and types.

  13. Aerosol volatility in a boreal forest environment

    NASA Astrophysics Data System (ADS)

    Häkkinen, S. A. K.; ńijälä, M.; Lehtipalo, K.; Junninen, H.; Virkkula, A.; Worsnop, D. R.; Kulmala, M.; Petäjä, T.; Riipinen, I.

    2012-04-01

    Climate and health effects of atmospheric aerosols are determined by their properties such as their chemical composition. Aerosol chemical composition can be studied indirectly by measuring volatility of aerosol particles. The volatility of submicron aerosol particles (20-500 nm) was studied in a boreal forest site at SMEAR II (Station for Measuring Ecosystem-Atmosphere Relations II) station (Vesala et al., 1998) in Hyytiälä, Finland, during 01/2008-05/2010. The instrument used for the measurements was VDMPS (Volatility Differential Mobility Particle Sizer), which consists of two separate instruments: DMPS (Differential Mobility Particle Sizer, Aalto et al., 2001) and TD (Thermodenuder, Wehner et al., 2002). Aerosol evaporation was examined by heating the aerosol and comparing the total aerosol mass before and after heating. In the VDMPS system ambient aerosol sample was heated up to temperatures ranging from 80 °C to 280 °C. The higher the heating temperature was the more aerosol material was evaporated. There was a non-volatile residual present in aerosol particles when heated up to 280 °C. This residual explained (20±8)% of the total aerosol mass. Aerosol non-volatile mass fraction was highest during winter and smallest during summer months. The role of black carbon in the observed non-volatile residual was determined. Black carbon explained 40 to 90% of the non-volatile mass. Especially during colder seasons noticeable amount of non-volatile material, something else than black carbon, was observed. According to Kalberer et al. (2004) some atmospheric organic species can form polymers that have high evaporation temperatures. Also low-volatile organic salts may contribute to the non-volatile aerosol (Smith et al., 2010). Aerosol mass composition measured directly with AMS (Aerosol Mass Spectrometer, Jayne et al., 2000) was analyzed in order to examine the properties of the non-volatile material (other than black carbon). The AMS measurements were performed

  14. The Dry Aerosol Deposition Device (DADD): An Instrument for Depositing Microbial Aerosols onto Surfaces

    DTIC Science & Technology

    2008-12-01

    AFRL-RX-TY-TR-2008-4592 THE DRY AEROSOL DEPOSITION DEVICE (DADD): AN INSTRUMENT FOR DEPOSITING MICROBIAL AEROSOLS ONTO SURFACES...RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (Include area code) 30-NOV-2008 Final Technical Report 01-OCT-2004 -- 02-OCT-2008 The Dry Aerosol Deposition ...Device (DADD): An Instrument for Depositing Microbial Aerosols Onto Surfaces FA4819-07-D-0001 99999F DODT 00 DODT0056 Heimbuch, Brian K.; Kinney

  15. The Dry Aerosol Deposition Device (DADD): An Instrument for Depositing Microbial Aerosols onto Surfaces (PREPRINT)

    DTIC Science & Technology

    2008-12-01

    AFRL-RX-TY-TP-2008-4617 PREPRINT THE DRY AEROSOL DEPOSITION DEVICE (DADD): AN INSTRUMENT FOR DEPOSITING MICROBIAL AEROSOLS ONTO SURFACES... Deposition Device (DADD): 3  An Instrument for Depositing Microbial Aerosols onto Surfaces 4  5  Authors and affiliation 6  7  Heimbuch, B.K., Kinney...footprint, variable loading, etc.). We developed a Dry Aerosol 33  Deposition Device (DADD) that uses impaction rather than settling for loading surfaces

  16. Aerosol Microphysics and Radiation Integration

    DTIC Science & Technology

    2005-09-30

    from the massive dust storm that occurred at the start of Operation Iraqi Freedom in late March 2003, may have been sampled during ADAM. COAMPS ...Along coastal and even some deep ocean regions, dust , pollution and smoke are often present and can dominate Electro-Optical (EO) effects over... COAMPS ®1) and the NRL Aerosol Analysis and Prediction System (NAAPS) require precise source and sink functions, as well as parameterizations for particle

  17. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2012-09-30

    prediction is now integrated, for example, with the COAMPS two- moment cloud microphysics scheme where it serves as a source of cloud droplet nuclei. The dust ...behavior. To evaluate the new handling of aerosol dust and its interaction with COAMPS microphysics, an operational test case has been developed...Sahara Air Layer (SAL) and Hurricane Nadine off of West Africa. Dust is seen wrapping around the north side of the storm on Sep 11 in Figure 2. We

  18. Nozzles for Focusing Aerosol Particles

    DTIC Science & Technology

    2009-10-01

    control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 1. REPORT DATE ( DD -MM-YYYY) October 2009 2. REPORT TYPE Final 3. DATES...Figures Figure 1. The design of the first-generation aerodynamic focusing nozzle for aerosol particles used for SPFS and TAOS instrument prototypes...Some nozzles were fabricated in aluminum and some in steel. It has been used for SPFS and TAOS measurement technologies both in the laboratory and

  19. Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements

    NASA Astrophysics Data System (ADS)

    Reed Espinosa, W.; Remer, Lorraine A.; Dubovik, Oleg; Ziemba, Luke; Beyersdorf, Andreas; Orozco, Daniel; Schuster, Gregory; Lapyonok, Tatyana; Fuertes, David; Vanderlei Martins, J.

    2017-03-01

    A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory measurements made by a novel polar nephelometer. This instrument, the Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy field measurements of phase function and degree of linear polarization, at three visible wavelengths, over a wide angular range of 3 to 177°. The resulting retrieval produces particle size distributions (PSDs) that agree, within experimental error, with measurements made by commercial optical particle counters (OPCs). Additionally, the retrieved real part of the refractive index is generally found to be within the predicted error of 0.02 from the expected values for three species of humidified salt particles, with a refractive index that is well established. The airborne measurements used in this work were made aboard the NASA DC-8 aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign, and the inversion of this data represents the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the real refractive index product, as well as in the retrieval's ability to accurately determine PSD, without assumptions about refractive index that are required by the majority of OPCs.

  20. Sensitivity metric approach for retrieval of aerosol properties from multiangular and multispectral polarized radiances.

    PubMed

    Miecznik, Grzegorz; Illing, Rainer; Petroy, Shelley; Sokolik, Irina N

    2005-07-10

    Linearly polarized radiation is sensitive to the microphysical properties of aerosols, namely, to the particle-size distribution and refractive index. The discriminating power of polarized radiation increases strongly with the increasing range of scattering angles and the addition of multiple wavelengths. The polarization and directionality of the Earth's reflectances (POLDER) missions demonstrate that some aerosol properties can be successfully derived from spaceborne polarimetric, multiangular measurements at two visible wavelengths. We extend the concept to analyze the retrieval capabilities of a spaceborne instrument with six polarimetric channels at 412, 445, 555, 865, 1250, and 2250 nm, measuring approximately 100 scattering angles covering a range between 50 and 150 deg. Our focus is development of an analysis methodology that can help quantify the benefits of such multiangular and multispectral polarimetric measurements. To that goal we employ a sensitivity metric approach in a framework of the principal-component analysis. The radiances and noise used to construct the sensitivity metric are calculated with the realistic solar flux for representative orbital viewing geometries, accounting for surface reflection from the ground, and statistical and calibration errors of a notional instrument. Spherical aerosol particles covering a range of representative microphysical properties (effective radius, effective variance, real and imaginary parts of the refractive index, single-scattering albedo) are considered in the calculations. We find that there is a limiting threshold for the effective size (approximately 0.7 microm), below which the weak scattering intensity results in a decreased signal-to-noise ratio and minimal polarization sensitivity, precluding reliable aerosol retrievals. For such small particles, close to the Rayleigh scattering limit, the total intensity provides a much stronger aerosol signature than the linear polarization, inspiring retrieval

  1. NASA GES DISC Level 2 Aerosol Analysis and Visualization Services

    NASA Technical Reports Server (NTRS)

    Wei, Jennifer; Petrenko, Maksym; Ichoku, Charles; Yang, Wenli; Johnson, James; Zhao, Peisheng; Kempler, Steve

    2015-01-01

    Overview of NASA GES DISC Level 2 aerosol analysis and visualization services: DQViz (Data Quality Visualization)MAPSS (Multi-sensor Aerosol Products Sampling System), and MAPSS_Explorer (Multi-sensor Aerosol Products Sampling System Explorer).

  2. AEROSOL INDUSTRY SUCCESS IN REDUCING CFC PROPELLANT USAGE

    EPA Science Inventory

    Part I of this report discusses the U.S. aerosol industry's experience in converting from chlorofluorocarbon (CFC) propellants to alternative aerosol formulations. Detailed examples of non-CFC formulations are provided for 28 categories of aerosol products. ydrocarbon propellants...

  3. Physical and Chemical Properties of Anthropogenic Aerosols: An Overview

    EPA Science Inventory

    Aerosol chemical composition is complex. Combustion aerosols can comprise tens of thousands of organic compounds, refractory brown and black carbon, heavy metals, cations, anions, salts, and other inorganic phases. Aerosol organic matter normally contains semivolatile material th...

  4. Aerosol from Organic Nitrogen in the Southeast United States

    EPA Science Inventory

    Biogenic volatile organic compounds (BVOCs) contribute significantly to organic aerosol in the southeastern United States. During the Southern Oxidant and Aerosol Study (SOAS), a portion of ambient organic aerosol was attributed to isoprene oxidation and organic nitrogen from BVO...

  5. Retrieval of Aerosol Microphysical Properties from AERONET Photo-Polarimetric Measurements. 2: A New Research Algorithm and Case Demonstration

    NASA Technical Reports Server (NTRS)

    Xu, Xiaoguang; Wang, Jun; Zeng, Jing; Spurr, Robert; Liu, Xiong; Dubovik, Oleg; Li, Li; Li, Zhengqiang; Mishchenko, Michael I.; Siniuk, Aliaksandr; Holben, Brent N.

    2015-01-01

    A new research algorithm is presented here as the second part of a two-part study to retrieve aerosol microphysical properties from the multispectral and multiangular photopolarimetric measurements taken by Aerosol Robotic Network's (AERONET's) new-generation Sun photometer. The algorithm uses an advanced UNified and Linearized Vector Radiative Transfer Model and incorporates a statistical optimization approach.While the new algorithmhas heritage from AERONET operational inversion algorithm in constraining a priori and retrieval smoothness, it has two new features. First, the new algorithmretrieves the effective radius, effective variance, and total volume of aerosols associated with a continuous bimodal particle size distribution (PSD) function, while the AERONET operational algorithm retrieves aerosol volume over 22 size bins. Second, our algorithm retrieves complex refractive indices for both fine and coarsemodes,while the AERONET operational algorithm assumes a size-independent aerosol refractive index. Mode-resolved refractive indices can improve the estimate of the single-scattering albedo (SSA) for each aerosol mode and thus facilitate the validation of satellite products and chemistry transport models. We applied the algorithm to a suite of real cases over Beijing_RADI site and found that our retrievals are overall consistent with AERONET operational inversions but can offer mode-resolved refractive index and SSA with acceptable accuracy for the aerosol composed by spherical particles. Along with the retrieval using both radiance and polarization, we also performed radiance-only retrieval to demonstrate the improvements by adding polarization in the inversion. Contrast analysis indicates that with polarization, retrieval error can be reduced by over 50% in PSD parameters, 10-30% in the refractive index, and 10-40% in SSA, which is consistent with theoretical analysis presented in the companion paper of this two-part study.

  6. Total ozone column, aerosol optical depth and precipitable water effects on solar erythemal ultraviolet radiation recorded in Malta.

    NASA Astrophysics Data System (ADS)

    Bilbao, Julia; Román, Roberto; Yousif, Charles; Mateos, David; Miguel, Argimiro

    2013-04-01

    The Universities of Malta and Valladolid (Spain) developed a measurement campaign, which took place in the Institute for Energy Technology in Marsaxlokk (Southern Malta) between May and October 2012, and it was supported by the Spanish government through the Project titled "Measurement campaign about Solar Radiation, Ozone, and Aerosol in the Mediterranean area" (with reference CGL2010-12140-E). This campaign provided the first ground-based measurements in Malta of erythemal radiation and UV index, which indicate the effectiveness of the sun exposure to produce sunburn on human skin. A wide variety of instruments was involved in the campaign, providing a complete atmospheric characterization. Data of erythemal radiation and UV index (from UVB-1 pyranometer), total shortwave radiaton (global and diffuse components from CM-6B pyranometers), and total ozone column, aerosol optical thickness, and precitable water column (from a Microtops-II sunphotometer) were available in the campaign. Ground-based and satellite instruments were used in the analysis, and several intercomparisons were carried out to validate remote sensing data. OMI, GOME, GOME-2, and MODIS instruments, which provide data of ozone, aerosol load and optical properties, were used to this end. The effects on solar radiation, ultraviolet and total shortwave ranges, of total ozone column, aerosol optical thickness and precipitable water column were obtained using radiation measurements at different fixed solar zenith angles. The empirical results shown a determinant role of the solar position, a negligible effect of ozone on total shortwave radiation, and a stronger attenuation provided by aerosol particles in the erythemal radiation. A variety of aerosol types from different sources (desert dust, biomass burning, continental, and maritime) reach Malta, in this campaign several dust events from the Sahara desert occurred and were analyzed establishing the air mass back-trajectories ending at Malta at

  7. SAGE II aerosol correlative observations - Profile measurements

    NASA Technical Reports Server (NTRS)

    Osborn, M. T.; Rosen, J. M.; Mccormick, M. P.; Wang, Pi-Huan; Livinfston, J. M.

    1989-01-01

    Profiles of the aerosol extinction measurements from the Stratospheric Aerosol and Gas Experiment (SAGE) II are compared with profiles from five correlative experiments between November 1984 and July 1986. The correlative profiles were derived from six-channel dustsonde measurements and two-wavelength lidar backscatter data. The correlation between the dustsonde- and lidar-derived measurements and the SAGE II data is good, validating the SAGE II lower stratospheric aerosol extinction measurements.

  8. Amino acids in Arctic aerosols

    NASA Astrophysics Data System (ADS)

    Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

    2012-11-01

    Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids and quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (< 0.49 μm) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanic emissions.

  9. Amino acids in Arctic aerosols

    NASA Astrophysics Data System (ADS)

    Scalabrin, E.; Zangrando, R.; Barbaro, E.; Kehrwald, N. M.; Gabrieli, J.; Barbante, C.; Gambaro, A.

    2012-07-01

    Amino acids are significant components of atmospheric aerosols, affecting organic nitrogen input to marine ecosystems, atmospheric radiation balance, and the global water cycle. The wide range of amino acid reactivities suggest that amino acids may serve as markers of atmospheric transport and deposition of particles. Despite this potential, few measurements have been conducted in remote areas to assess amino acid concentrations and potential sources. Polar regions offer a unique opportunity to investigate atmospheric processes and to conduct source apportionment studies of such compounds. In order to better understand the importance of amino acid compounds in the global atmosphere, we determined free amino acids (FAAs) in seventeen size-segregated aerosol samples collected in a polar station in the Svalbard Islands from 19 April until 14 September 2010. We used an HPLC coupled with a tandem mass spectrometer (ESI-MS/MS) to analyze 20 amino acids to quantify compounds at fmol m-3 levels. Mean total FAA concentration was 1070 fmol m-3 where serine and glycine were the most abundant compounds in almost all samples and accounted for 45-60% of the total amino acid relative abundance. The other eighteen compounds had average concentrations between 0.3 and 98 fmol m-3. The higher amino acid concentrations were present in the ultrafine aerosol fraction (<0.49 μm) and accounted for the majority of the total amino acid content. Local marine sources dominate the boreal summer amino acid concentrations, with the exception of the regional input from Icelandic volcanics.

  10. Ice-condenser aerosol tests

    SciTech Connect

    Ligotke, M.W.; Eschbach, E.J.; Winegardner, W.K. )

    1991-09-01

    This report presents the results of an experimental investigation of aerosol particle transport and capture using a full-scale height and reduced-scale cross section test facility based on the design of the ice compartment of a pressurized water reactor (PWR) ice-condenser containment system. Results of 38 tests included thermal-hydraulic as well as aerosol particle data. Particle retention in the test section was greatly influenced by thermal-hydraulic and aerosol test parameters. Test-average decontamination factor (DF) ranged between 1.0 and 36 (retentions between {approximately}0 and 97.2%). The measured test-average particle retentions for tests without and with ice and steam ranged between DF = 1.0 and 2.2 and DF = 2.4 and 36, respectively. In order to apparent importance, parameters that caused particle retention in the test section in the presence of ice were steam mole fraction (SMF), noncondensible gas flow rate (residence time), particle solubility, and inlet particle size. Ice-basket section noncondensible flows greater than 0.1 m{sup 3}/s resulted in stable thermal stratification whereas flows less than 0.1 m{sup 3}/s resulted in thermal behavior termed meandering with frequent temperature crossovers between flow channels. 10 refs., 66 figs., 16 tabs.

  11. Quantification of aerosol type, and sources of aerosols over the Indo-Gangetic Plain

    NASA Astrophysics Data System (ADS)

    Kedia, Sumita; Ramachandran, S.; Holben, B. N.; Tripathi, S. N.

    2014-12-01

    Differences and similarities in aerosol characteristics, for the first time, over two environmentally distinct locations in Indo-Gangetic plain (IGP) - Kanpur (KPR) (urban location) and Gandhi College (GC) (rural site) are examined. Aerosol optical depths (AODs) exhibit pronounced seasonal variability with higher values during winter and premonsoon. Aerosol fine mode fraction (FMF) and Ångström exponent (α) are higher over GC than KPR indicating relatively higher fine mode aerosol concentration over GC. Higher FMF over GC is attributed to local biomass burning activities. Analysis of AOD spectra revealed that aerosol size distribution is dominated by wide range of fine mode fractions or mixture of modes during winter and postmonsoon, while during premonsoon and monsoon coarse mode aerosols are more abundant. Single scattering albedo (SSA) is lower over GC than KPR. SSA spectra reveals the abundance of fine mode (coarse mode) absorbing (scattering) aerosols during winter and postmonsoon (premonsoon and monsoon). Spectral SSA features reveal that OC contribution to enhanced absorption is negligible. Analysis shows that absorbing aerosols can be classified as Mostly Black Carbon (BC), and Mixed BC and Dust over IGP. Mixed BC and dust is always higher over KPR, while Mostly BC is higher over GC throughout the year. The amount of long range transported dust exhibits a gradient between KPR (higher) and GC (lower). Results on seasonally varying aerosol types, and absorbing aerosol types and their gradients over an aerosol hotspot are important to tune models and to reduce the uncertainty in radiative and climate impact of aerosols.

  12. Aerosol Lidar and MODIS Satellite Comparisons for Future Aerosol Loading Forecast

    NASA Technical Reports Server (NTRS)

    DeYoung, Russell; Szykman, James; Severance, Kurt; Chu, D. Allen; Rosen, Rebecca; Al-Saadi, Jassim

    2006-01-01

    Knowledge of the concentration and distribution of atmospheric aerosols using both airborne lidar and satellite instruments is a field of active research. An aircraft based aerosol lidar has been used to study the distribution of atmospheric aerosols in the California Central Valley and eastern US coast. Concurrently, satellite aerosol retrievals, from the MODIS (Moderate Resolution Imaging Spectroradiometer) instrument aboard the Terra and Aqua satellites, were take over the Central Valley. The MODIS Level 2 aerosol data product provides retrieved ambient aerosol optical properties (e.g., optical depth (AOD) and size distribution) globally over ocean and land at a spatial resolution of 10 km. The Central Valley topography was overlaid with MODIS AOD (5x5 sq km resolution) and the aerosol scattering vertical profiles from a lidar flight. Backward air parcel trajectories for the lidar data show that air from the Pacific and northern part of the Central Valley converge confining the aerosols to the lower valley region and below the mixed layer. Below an altitude of 1 km, the lidar aerosol and MODIS AOD exhibit good agreement. Both data sets indicate a high presence of aerosols near Bakersfield and the Tehachapi Mountains. These and other results to be presented indicate that the majority of the aerosols are below the mixed layer such that the MODIS AOD should correspond well with surface measurements. Lidar measurements will help interpret satellite AOD retrievals so that one day they can be used on a routine basis for prediction of boundary layer aerosol pollution events.

  13. A Multiple Regression Analysis Between UV Radiation Measurements at Badajoz and Ozone, Reflectivity and Aerosols Estimated by TOMS

    NASA Astrophysics Data System (ADS)

    Antón, M.; Cancillo, M. L.; Serrano, A.; García, J. A.

    2005-01-01

    This paper analyzes the relationship between ultraviolet erythemal radiation (UVER) measured in Badajoz (Spain) and ozone, cloudiness and aerosols. Initially, the values of transmissivity of UVER are related with three parameters (ozone amount, reflectivity and aerosol index) estimated by the satellite instrument TOMS. The relative importance and dependence of each variable is analyzed by means of a multiple regression analysis with an expression derived from the Lambert-Bouger-Beer law. The results indicate that the aerosol index is not a statistically significant factor for the initial expression. Then, a partial model with only ozone and reflectivity as regressors is proposed and coefficients are obtained using UVER measurements of year 2001. Finally the model is validated comparing its prediction for 2002 with UVER measurements at ground. The agreement between both data sets is reasonably good, suggesting that UVER estimations can be successfully derived from observations of other atmospheric variables, thus providing the basis to obtain spatial distributed maps of UV variations.

  14. Effects of Microbial Aerosol in Poultry House on Meat Ducks' Immune Function.

    PubMed

    Yu, Guanliu; Wang, Yao; Wang, Shouguo; Duan, Changmin; Wei, Liangmeng; Gao, Jing; Chai, Tongjie; Cai, Yumei

    2016-01-01

    The aim of this study was to evaluate effects of microbial aerosols on immune function of ducks and shed light on the establishment of microbial aerosol concentration standards for poultry. A total of 1800 1-d-old cherry valley ducks were randomly divided into five groups (A, B, C, D, and E) with 360 ducks in each. To obtain objective data, each group had three replications. Concentrations of airborne bacteria, fungi, endotoxin in different groups were created by controlling ventilation and bedding cleaning frequency. Group A was the control group and hygienic conditions deteriorated progressively from group B to E. A 6-stage Andersen impactor was used to detect the aerosol concentration of aerobes, gram-negative bacteria, fungi, and AGI-30 microbial air sampler detect the endotoxin, and Composite Gas Detector detect the noxious gas. In order to assess the immune function of meat ducks, immune indicators including H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme and immune organ indexes were evaluated. Correlation coefficients were also calculated to evaluate the relationships among airborne bacteria, fungi, endotoxin, and immune indicators. The results showed that the concentration of airborne aerobe, gram-negative bacteria, fungi, endotoxin have a strong correlation to H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme, and immune organ indexes, respectively. In addition, when the concentration of microbial aerosol reach the level of group D, serum IgG (6-8 weeks), lysozyme (4 week) were significantly higher than in group A (P < 0.05); serum IL-2 (7 and 8 weeks), T-lymphocyte transformation rate, lysozyme (7 and 8 weeks), spleen index (6 and 8 weeks), and bursa index (8 week) were significantly lower than in group A (P < 0.05 or P < 0.01). The results indicated that a high level of microbial aerosol adversely affected the immune level of meat ducks. The microbial aerosol values in group D provide a basis for

  15. Effects of Microbial Aerosol in Poultry House on Meat Ducks' Immune Function

    PubMed Central

    Yu, Guanliu; Wang, Yao; Wang, Shouguo; Duan, Changmin; Wei, Liangmeng; Gao, Jing; Chai, Tongjie; Cai, Yumei

    2016-01-01

    The aim of this study was to evaluate effects of microbial aerosols on immune function of ducks and shed light on the establishment of microbial aerosol concentration standards for poultry. A total of 1800 1-d-old cherry valley ducks were randomly divided into five groups (A, B, C, D, and E) with 360 ducks in each. To obtain objective data, each group had three replications. Concentrations of airborne bacteria, fungi, endotoxin in different groups were created by controlling ventilation and bedding cleaning frequency. Group A was the control group and hygienic conditions deteriorated progressively from group B to E. A 6-stage Andersen impactor was used to detect the aerosol concentration of aerobes, gram-negative bacteria, fungi, and AGI-30 microbial air sampler detect the endotoxin, and Composite Gas Detector detect the noxious gas. In order to assess the immune function of meat ducks, immune indicators including H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme and immune organ indexes were evaluated. Correlation coefficients were also calculated to evaluate the relationships among airborne bacteria, fungi, endotoxin, and immune indicators. The results showed that the concentration of airborne aerobe, gram-negative bacteria, fungi, endotoxin have a strong correlation to H5 AIV antibody titer, IgG, IL-2, T-lymphocyte transformation rate, lysozyme, and immune organ indexes, respectively. In addition, when the concentration of microbial aerosol reach the level of group D, serum IgG (6–8 weeks), lysozyme (4 week) were significantly higher than in group A (P < 0.05); serum IL-2 (7 and 8 weeks), T-lymphocyte transformation rate, lysozyme (7 and 8 weeks), spleen index (6 and 8 weeks), and bursa index (8 week) were significantly lower than in group A (P < 0.05 or P < 0.01). The results indicated that a high level of microbial aerosol adversely affected the immune level of meat ducks. The microbial aerosol values in group D provide a basis for

  16. Multi-Sensor Aerosol Products Sampling System

    NASA Technical Reports Server (NTRS)

    Petrenko, M.; Ichoku, C.; Leptoukh, G.

    2011-01-01

    Global and local properties of atmospheric aerosols have been extensively observed and measured using both spaceborne and ground-based instruments, especially during the last decade. Unique properties retrieved by the different instruments contribute to an unprecedented availability of the most complete set of complimentary aerosol measurements ever acquired. However, some of these measurements remain underutilized, largely due to the complexities involved in analyzing them synergistically. To characterize the inconsistencies and bridge the gap that exists between the sensors, we have established a Multi-sensor Aerosol Products Sampling System (MAPSS), which consistently samples and generates the spatial statistics (mean, standard deviation, direction and rate of spatial variation, and spatial correlation coefficient) of aerosol products from multiple spacebome sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS. Samples of satellite aerosol products are extracted over Aerosol Robotic Network (AERONET) locations as well as over other locations of interest such as those with available ground-based aerosol observations. In this way, MAPSS enables a direct cross-characterization and data integration between Level-2 aerosol observations from multiple sensors. In addition, the available well-characterized co-located ground-based data provides the basis for the integrated validation of these products. This paper explains the sampling methodology and concepts used in MAPSS, and demonstrates specific examples of using MAPSS for an integrated analysis of multiple aerosol products.

  17. Sodium cromoglycate: spincaps or metered dose aerosol.

    PubMed Central

    Robson, R A; Taylor, B J; Taylor, B

    1981-01-01

    1 Sodium cromoglycate administered as a dry powder inhalation (20 mg/dose) via the Spinhaler was compared with a metered dose aerosol (2 mg/dose) in an eight week double dummy double blind crossover trial in 29 asthmatic children. 2 The powder formulation was associated with significantly less symptoms (night wheeze, night cough, day wheeze, day cough, activity) and bronchodilator intake; and significantly greater weight gain than aerosol therapy. There were no significant differences in morning or evening peak flow measurements on the two treatments. 3 The powder may be more effectively inhaled than the aerosol or the dose of the aerosol may not be large enough. PMID:6789851

  18. Separating Cloud Forming Nuclei from Interstitial Aerosol

    SciTech Connect

    Kulkarni, Gourihar R.

    2012-09-12

    It has become important to characterize the physicochemical properties of aerosol that have initiated the warm and ice clouds. The data is urgently needed to better represent the aerosol-cloud interaction mechanisms in the climate models. The laboratory and in-situ techniques to separate precisely the aerosol particles that act as cloud condensation nuclei (CCN) and ice nuclei (IN), termed as cloud nuclei (CN) henceforth, have become imperative in studying aerosol effects on clouds and the environment. This review summarizes these techniques, design considerations, associated artifacts and challenges, and briefly discusses the need for improved designs to expand the CN measurement database.

  19. The boiling point of stratospheric aerosols.

    NASA Technical Reports Server (NTRS)

    Rosen, J. M.

    1971-01-01

    A photoelectric particle counter was used for the measurement of aerosol boiling points. The operational principle involves raising the temperature of the aerosol by vigorously heating a portion of the intake tube. At or above the boiling point, the particles disintegrate rather quickly, and a noticeable effect on the size distribution and concentration is observed. Stratospheric aerosols appear to have the same volatility as a solution of 75% sulfuric acid. Chemical analysis of the aerosols indicates that there are other substances present, but that the sulfate radical is apparently the major constituent.

  20. The Aerosol/Cloud/Ecosystems Mission (ACE)

    NASA Technical Reports Server (NTRS)

    Schoeberl, Mark

    2008-01-01

    The goals and measurement strategy of the Aerosol/Cloud/Ecosystems Mission (ACE) are described. ACE will help to answer fundamental science questions associated with aerosols, clouds, air quality and global ocean ecosystems. Specifically, the goals of ACE are: 1) to quantify aerosol-cloud interactions and to assess the impact of aerosols on the hydrological cycle and 2) determine Ocean Carbon Cycling and other ocean biological processes. It is expected that ACE will: narrow the uncertainty in aerosol-cloud-precipitation interaction and quantify the role of aerosols in climate change; measure the ocean ecosystem changes and precisely quantify ocean carbon uptake; and, improve air quality forecasting by determining the height and type of aerosols being transported long distances. Overviews are provided of the aerosol-cloud community measurement strategy, aerosol and cloud observations over South Asia, and ocean biology research goals. Instruments used in the measurement strategy of the ACE mission are also highlighted, including: multi-beam lidar, multiwavelength high spectra resolution lidar, the ocean color instrument (ORCA)--a spectroradiometer for ocean remote sensing, dual frequency cloud radar and high- and low-frequency micron-wave radiometer. Future steps for the ACE mission include refining measurement requirements and carrying out additional instrument and payload studies.

  1. Electronic cigarette solutions and resultant aerosol profiles.

    PubMed

    Herrington, Jason S; Myers, Colton

    2015-10-30

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

  2. In Situ Measurements of Aerosol Mass Concentration and Spectral Absorption in Xianghe, SE of Beijing, China

    NASA Astrophysics Data System (ADS)

    Chaudhry, Z.; Martins, V.; Li, Z.

    2005-12-01

    China's rapid industrialization over the last few decades has affected air quality in many regions of China, and even the regional climate. As a part of the EAST-AIRE (East Asian Study of Tropospheric Aerosols: an International Regional Experiment) study, Nuclepore filters were collected in two size ranges (PM10 and PM2.5) at 12 hour intervals since January 2005 at Xianghe, about 70 km southeast of Beijing. Each filter was analyzed for mass concentration, aerosol scattering and absorption efficiencies. Mass concentrations during the winter months (January-March) ranged from 9 to 459 μg/m3 in the coarse mode with an average concentration of 122 μg/m3, and from 11 to 203 μg/m3 in the fine mode with an average concentration of 45 μg/m3. While some of the extreme values are likely linked to local emissions, regional air pollution episodes also played important roles. Absorption efficiency measurements at 550 nm show very high values compared to measurements performed in the United States during the CLAMS experiment. The spectral mass absorption efficiency was measured from 350 to 2500 nm and shows large differences between the absorption properties of soil dust, black carbon, and organic aerosols. The strong spectral differences observed can be related to differences in refractive indices from the several collected species and particle size effects. The absorption properties from aerosols measured in China show large absorption efficiencies, compared to aerosols measured in the US, possibly linked to different technology practices used in these countries. For organic plus black carbon aerosols, where the refractive index seems to be relatively constant, the absorption efficiency spectral dependence for fine mode aerosols falls between 1/λ and 1/λ2. The coarse mode absorption shows much less spectral dependence.

  3. The single scattering properties of the aerosol particles as aggregated spheres

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Gu, X.; Cheng, T.; Xie, D.; Yu, T.; Chen, H.; Guo, J.

    2012-08-01

    The light scattering and absorption properties of anthropogenic aerosol particles such as soot aggregates are complicated in the temporal and spatial distribution, which introduce uncertainty of radiative forcing on global climate change. In order to study the single scattering properties of anthorpogenic aerosol particles, the structures of these aerosols such as soot paticles and soot-containing mixtures with the sulfate or organic matter, are simulated using the parallel diffusion limited aggregation algorithm (DLA) based on the transmission electron microscope images (TEM). Then, the single scattering properties of randomly oriented aerosols, such as scattering matrix, single scattering albedo (SSA), and asymmetry parameter (AP), are computed using the superposition T-matrix method. The comparisons of the single scattering properties of these specific types of clusters with different morphological and chemical factors such as fractal parameters, aspect ratio, monomer radius, mixture mode and refractive index, indicate that these different impact factors can respectively generate the significant influences on the single scattering properties of these aerosols. The results show that aspect ratio of circumscribed shape has relatively small effect on single scattering properties, for both differences of SSA and AP are less than 0.1. However, mixture modes of soot clusters with larger sulfate particles have remarkably important effects on the scattering and absorption properties of aggregated spheres, and SSA of those soot-containing mixtures are increased in proportion to the ratio of larger weakly absorbing attachments. Therefore, these complex aerosols come from man made pollution cannot be neglected in the aerosol retrievals. The study of the single scattering properties on these kinds of aggregated spheres is important and helpful in remote sensing observations and atmospheric radiation balance computations.

  4. An algorithm for hyperspectral remote sensing of aerosols: 1. Development of theoretical framework

    NASA Astrophysics Data System (ADS)

    Hou, Weizhen; Wang, Jun; Xu, Xiaoguang; Reid, Jeffrey S.; Han, Dong

    2016-07-01

    This paper describes the first part of a series of investigations to develop algorithms for simultaneous retrieval of aerosol parameters and surface reflectance from a newly developed hyperspectral instrument, the GEOstationary Trace gas and Aerosol Sensor Optimization (GEO-TASO), by taking full advantage of available hyperspectral measurement information in the visible bands. We describe the theoretical framework of an inversion algorithm for the hyperspectral remote sensing of the aerosol optical properties, in which major principal components (PCs) for surface reflectance is assumed known, and the spectrally dependent aerosol refractive indices are assumed to follow a power-law approximation with four unknown parameters (two for real and two for imaginary part of refractive index). New capabilities for computing the Jacobians of four Stokes parameters of reflected solar radiation at the top of the atmosphere with respect to these unknown aerosol parameters and the weighting coefficients for each PC of surface reflectance are added into the UNified Linearized Vector Radiative Transfer Model (UNL-VRTM), which in turn facilitates the optimization in the inversion process. Theoretical derivations of the formulas for these new capabilities are provided, and the analytical solutions of Jacobians are validated against the finite-difference calculations with relative error less than 0.2%. Finally, self-consistency check of the inversion algorithm is conducted for the idealized green-vegetation and rangeland surfaces that were spectrally characterized by the U.S. Geological Survey digital spectral library. It shows that the first six PCs can yield the reconstruction of spectral surface reflectance with errors less than 1%. Assuming that aerosol properties can be accurately characterized, the inversion yields a retrieval of hyperspectral surface reflectance with an uncertainty of 2% (and root-mean-square error of less than 0.003), which suggests self-consistency in the

  5. Vegetation fires, absorbing aerosols and smoke plume characteristics in diverse biomass burning regions of Asia

    NASA Astrophysics Data System (ADS)

    Prasad Vadrevu, Krishna; Lasko, Kristofer; Giglio, Louis; Justice, Chris

    2015-10-01

    In this study, we explored the relationships between the satellite-retrieved fire counts (FC), fire radiative power (FRP) and aerosol indices using multi-satellite datasets at a daily time-step covering ten different biomass burning regions in Asia. We first assessed the variations in MODIS-retrieved aerosol optical depths (AOD’s) in agriculture, forests, plantation and peat land burning regions and then used MODIS FC and FRP (hereafter FC/FRP) to explain the variations in AOD characteristics. Results suggest that tropical broadleaf forests in Laos burn more intensively than the other vegetation fires. FC/FRP-AOD correlations in different agricultural residue burning regions did not exceed 20% whereas in forest regions they reached 40%. To specifically account for absorbing aerosols, we used Ozone Monitoring Instrument-derived aerosol absorption optical depth (AAOD) and UV aerosol index (UVAI). Results suggest relatively high AAOD and UVAI values in forest fires compared with peat and agriculture fires. Further, FC/FRP could explain a maximum of 29% and 53% of AAOD variations, whereas FC/FRP could explain at most 33% and 51% of the variation in agricultural and forest biomass burning regions, respectively. Relatively, UVAI was found to be a better indicator than AOD and AAOD in both agriculture and forest biomass burning plumes. Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations data showed vertically elevated aerosol profiles greater than 3.2-5.3 km altitude in the forest fire plumes compared to 2.2-3.9 km and less than 1 km in agriculture and peat-land fires, respectively. We infer the need to assimilate smoke plume height information for effective characterization of pollutants from different sources.

  6. Potential vorticity index

    NASA Technical Reports Server (NTRS)

    Barcilon, Albert; Weng, Hengyi

    1990-01-01

    Using standard data analysis techniques, researchers explore the links between disturbance growth and quasi-geostrophic potential vorticity (PV) gradients; appearance and disappearance of cutoff lows and blocking highs and their relation to a zonal index (properly defined in terms of PV); and teleconnections between different flow patterns and their relation to the zonal index. It was found that the PV index and the eddy index correlate better than a zonal index (defined by zonal wind) and the eddy index. In the frequency domain there are three frequencies (.03, .07 and .17 cpd (cycle per day) corresponding to periods of 33, 14 and 6 days) at which PV index and the eddy index exhibit local maxima. The high correlation found at periods of 33 days is mainly due to eddy activity at high latitudes while the local correlation maxima found at the shorter periods are mainly due mid-latitude eddy activity. The correlation between the PV index and the geopotential height anomaly at 500 mb, at each grid point in the Northern Hemisphere, shows the existence of most of the teleconnection patterns summarized by Wallace and Gutzler (1981): the North Atlantic Oscillation, the North Pacific Oscillation, and the Pacific/North American patterns. Results show that the Isentropic Potential Vorticity (IPV) analysis can be a very useful and powerful tool when used to understand the dynamics of several large scale atmospheric systems. Although the data are limited to only one winter, and it is difficult to assess the statistical significance of the correlation coefficients presented here, the results are encouraging from physical viewpoint.

  7. Effects of crop residue burning on aerosol properties, plume characteristics, and long-range transport over northern India

    NASA Astrophysics Data System (ADS)

    Kaskaoutis, D. G.; Kumar, S.; Sharma, D.; Singh, R. P.; Kharol, S. K.; Sharma, M.; Singh, A. K.; Singh, S.; Singh, Atinderpal; Singh, D.

    2014-05-01

    Aerosol emissions from biomass burning are of specific interest over the globe due to their strong radiative impacts and climate implications. The present study examines the impact of paddy crop residue burning over northern India during the postmonsoon (October-November) season of 2012 on modification of aerosol properties, as well as the long-range transport of smoke plumes, altitude characteristics, and affected areas via the synergy of ground-based measurements and satellite observations. During this period, Moderate Resolution Imaging Spectroradiometer (MODIS) images show a thick smoke/hazy aerosol layer below 2-2.5 km in the atmosphere covering nearly the whole Indo-Gangetic Plains (IGP). The air mass trajectories originating from the biomass-burning source region over Punjab at 500 m reveal a potential aerosol transport pathway along the Ganges valley from west to east, resulting in a strong aerosol optical depth (AOD) gradient. Sometimes, depending upon the wind direction and meteorological conditions, the plumes also influence central India, the Arabian Sea, and the Bay of Bengal, thus contributing to Asian pollution outflow. The increased number of fire counts (Terra and Aqua MODIS data) is associated with severe aerosol-laden atmospheres (AOD500 nm > 1.0) over six IGP locations, high values of Ångström exponent (>1.2), high particulate mass 2.5 (PM2.5) concentrations (>100-150 µgm-3), and enhanced Ozone Monitoring Instrument Aerosol Index gradient (~2.5) and NO2 concentrations (~6 × 1015 mol/cm2), indicating the dominance of smoke aerosols from agricultural crop residue burning. The aerosol size distribution is shifted toward the fine-mode fraction, also exhibiting an increase in the radius of fine aerosols due to coagulation processes in a highly turbid environment. The spectral variation of the single-scattering albedo reveals enhanced dominance of moderately absorbing aerosols, while the aerosol properties, modification, and mixing atmospheric

  8. Index Construction, A Bibliography.

    DTIC Science & Technology

    1984-09-01

    Application in Science, S5G37 Technology , and Humanities, N.Y., N.Y: John Wiley & Sons, C 1969. Z695.9 Harrod, Leonard Montague, ed. Indexers on... Indexing Terminology, Posting Terms and KWOC, DESK Alexandria, VA: DDC, May, 1979. Z1035.1 Library of Congress. Main Reading Room, Reference Collection...A1544 750 INDEX CONSTRUCTON AR BI OGRAPHYU ARMY FIEL ARTILERY SHOOL FORT SIL OR MILE R SEP 84 USA FASM -DSB- A0 VNtASIIEFG 5/2 NI MONSOONSfl 0841

  9. Glycemic index and disease.

    PubMed

    Pi-Sunyer, F Xavier

    2002-07-01

    It has been suggested that foods with a high glycemic index are detrimental to health and that healthy people should be told to avoid these foods. This paper takes the position that not enough valid scientific data are available to launch a public health campaign to disseminate such a recommendation. This paper explores the glycemic index and its validity and discusses the effect of postprandial glucose and insulin responses on food intake, obesity, type 1 diabetes, and cardiovascular disease. Presented herein are the reasons why it is premature to recommend that the general population avoid foods with a high glycemic index.

  10. Aerosol Seasonal Variations over Urban-Industrial Regions in Ukraine According to AERONET and POLDER Measurements

    NASA Technical Reports Server (NTRS)

    Milinevsky, G.; Danylevsky, V.; Bovchaliuk, V.; Bovchaliuk, A.; Goloub, Ph.; Dubovik, O.; Kabashnikov, V.; Chaikovsky, A.; Miatselskaya, N.; Mishchenko, M.; Sosonkin, M.

    2014-01-01

    The paper presents an investigation of aerosol seasonal variations in several urban-industrial regions in Ukraine. Our analysis of seasonal variations of optical and physical aerosol parameters is based on the sun-photometer 2008-2013 data from two urban ground-based AERONET (AErosol RObotic NETwork) sites in Ukraine (Kyiv, Lugansk) as well as on satellite POLDER instrument data for urban-industrial areas in Ukraine. We also analyzed the data from one AERONET site in Belarus (Minsk) in order to compare with the Ukrainian sites. Aerosol amount and optical depth (AOD) values in the atmosphere columns over the large urbanized areas like Kyiv and Minsk have maximum values in the spring (April-May) and late summer (August), whereas minimum values are observed in late autumn. The results show that fine-mode particles are most frequently detected during the spring and late summer seasons. The analysis of the seasonal AOD variations over the urban-industrial areas in the eastern and central parts of Ukraine according to both ground-based and POLDER data exhibits the similar traits. The seasonal variation similarity in the regions denotes the resemblance in basic aerosol sources that are closely related to properties of aerosol particles. The behavior of basic aerosol parameters in the western part of Ukraine is different from eastern and central regions and shows an earlier appearance of the spring and summer AOD maxima. Spectral single-scattering albedo, complex refractive index and size distribution of aerosol particles in the atmosphere column over Kyiv have different behavior for warm (April-October) and cold seasons. The seasonal features of fine and coarse aerosol particle behavior over the Kyiv site were analyzed. A prevailing influence of the fine-mode particles on the optical properties of the aerosol layer over the region has been established. The back-trajectory and cluster analysis techniques were applied to study the seasonal back trajectories and prevailing

  11. A Comprehensive Archive of Aerosol and Trace Gas Spatial Distributions for Model and Satellite Validation

    NASA Astrophysics Data System (ADS)

    Wilson, J. C.; Meland, B. S.; Axisa, D.

    2015-12-01

    The University of Denver Aerosol Group has assembled measured aerosol size distributions, gaseous concentrations, and atmospheric state variables covering a 30 year time period into one comprehensive archive. Measurements were made during the period 1987-2013 and include data from a total of 21 NASA field campaigns. Measurements were taken from the ground to over 21 km in altitude, from 72 S Latitude to 90 N latitude on over 300 individual flights on NASA Research Aircraft. Aerosol measurements were made with the University of Denver's Nucleation-Mode Aerosol Size Spectrometer (NMASS), Focused Cavity Aerosol Spectrometer, and/or a low-pressure Condensation Particle Counter (CPC) depending on the specific campaign. The science payloads varied with the campaign objectives, but the aerosol data were invariably acquired in conjunction with measurements by other investigators placing them in the context of atmospheric composition. The archive includes location and time of the measurements along with the tropopause heights and selected atmospheric composition and state data such as ambient temperatures and pressures, abundances of ozone, N2O, oxides of nitrogen, water vapor, CO2 etc. The data archive is stored in NetCDF format and includes all relevant metadata for measured quantities. This archive will be hosted by NASA and will be available to the public for model validation. The data includes indexing by scientific campaign, date, and spatial coordinates. This will facilitate comparisons across the available range of times, locations and related measurements. This data set has been used for validation of satellite remote sensing data. Coincident measurements of aerosol size distributions were used to calculate extinction profiles which were compared to those retrieved with the SAGE II satellite. Agreement between extinctions derived from the in situ size measurements and those provided by SAGE II was good for the 452, 525, and 1020 nm wavelength channels, but poor for

  12. Aerosol seasonal variations over urban sites in Ukraine and Belarus according to AERONET and POLDER measurements

    NASA Astrophysics Data System (ADS)

    Milinevsky, G.; Danylevsky, V.; Bovchaliuk, V.; Bovchaliuk, A.; Goloub, Ph.; Dubovik, O.; Kabashnikov, V.; Chaikovsky, A.; Mishchenko, M.; Sosonkin, M.

    2013-12-01

    The paper presents an investigation of aerosol seasonal variations in several urban sites in the East European region. Our analysis of seasonal variations of optical and physical aerosol parameters is based on the sun-photometer 2008-2012 data from three urban ground-based AERONET sites in Ukraine (Kyiv, Kyiv-AO, and Lugansk) and one site in Belarus (Minsk), as well as on satellite POLDER instrument data for urban areas in Ukraine. Aerosol amount and optical thickness values exhibit peaks in the spring (April-May) and late summer (August), whereas minimum values are seen in late autumn over the Kyiv and Minsk sites. The results show that aerosol fine mode particles are most frequently detected during the spring and late summer seasons. The seasonal variation similarity in the two regions points to the resemblance in basic aerosol sources which are closely related to properties of aerosol particles. However the aerosol amount and properties change noticeably from year to year and from region to region. The analysis of seasonal aerosol optical thickness variations over the urban sites in the eastern and western parts of Ukraine according to both ground-based and POLDER data exhibits the same traits. In particular, over Kyiv, the values of the Angstrom exponent are lower in April of 2011 than in 2009 and 2010, while aerosol optical thickness values are almost the same, which can be explained by an increase in the amount of coarse mode particles in the atmosphere, such as Saharan dust. Moreover, the coarse mode particles prevailed over suburbs and the center of Kyiv during a third of all available days of observation in 2012. In general, the fine and coarse mode particles' modal radii averaged over 2008-2012 range from 0.1 to 0.2 μm and 2 to 5 μm, respectively, during the period from April to September. The single scattering albedo and refractive index values of these particles correspond to a mix of urban-industrial, biomass burning, and dust aerosols. In addition

  13. Aerosol seasonal variations over urban-industrial regions in Ukraine according to AERONET and POLDER measurements

    NASA Astrophysics Data System (ADS)

    Milinevsky, G.; Danylevsky, V.; Bovchaliuk, V.; Bovchaliuk, A.; Goloub, Ph.; Dubovik, O.; Kabashnikov, V.; Chaikovsky, A.; Miatselskaya, N.; Mishchenko, M.; Sosonkin, M.

    2014-05-01

    The paper presents an investigation of aerosol seasonal variations in several urban-industrial regions in Ukraine. Our analysis of seasonal variations of optical and physical aerosol parameters is based on the sun-photometer 2008-2013 data from two urban ground-based AERONET (AErosol RObotic NETwork) sites in Ukraine (Kyiv, Lugansk) as well as on satellite POLDER instrument data for urban-industrial areas in Ukraine. We also analyzed the data from one AERONET site in Belarus (Minsk) in order to compare with the Ukrainian sites. Aerosol amount and optical depth (AOD) values in the atmosphere columns over the large urbanized areas like Kyiv and Minsk have maximum values in the spring (April-May) and late summer (August), whereas minimum values are observed in late autumn. The results show that fine-mode particles are most frequently detected during the spring and late summer seasons. The analysis of the seasonal AOD variations over the urban-industrial areas in the eastern and central parts of Ukraine according to both ground-based and POLDER data exhibits the similar traits. The seasonal variation similarity in the regions denotes the resemblance in basic aerosol sources that are closely related to properties of aerosol particles. The behavior of basic aerosol parameters in the western part of Ukraine is different from eastern and central regions and shows an earlier appearance of the spring and summer AOD maxima. Spectral single-scattering albedo, complex refractive index and size distribution of aerosol particles in the atmosphere column over Kyiv have different behavior for warm (April-October) and cold seasons. The seasonal features of fine and coarse aerosol particle behavior over the Kyiv site were analyzed. A prevailing influence of the fine-mode particles on the optical properties of the aerosol layer over the region has been established. The back-trajectory and cluster analysis techniques were applied to study the seasonal back trajectories and prevailing

  14. The Influence of Atmospheric Aerosols on Air Quality Status of the Egyptian Nile Delta

    NASA Astrophysics Data System (ADS)

    El-Askary, H. M.; Zakey, A.

    2014-12-01

    Due to the combination of natural and anthropogenic sources of emission over the Nile Delta region, the air quality status is very poor and has a significant health hazards impacts on the population. Here we focused on the optical and chemical characterizations of atmospheric aerosols in the Nile Delta using the online integrated Environmental-Climate Aerosols model (EnvClimA) during a 10 year period 2000-2010. Observations from MODIS and SeaWiFS measurements supplemented by CALIPSO and some ground-based data from AERONET, are used to validate the EnvClimA model and to illustrate the aerosol characteristics and their sources. CALIPSO measurements were used to characterize the vertical structure of aerosols and their shapes (spherical and non-spherical) for major dust storms and biomass burning events. In this study we discussed the synoptic patterns and features, which are associated with either the dust storm or high pollution events. We used MODIS derived aerosol parameters to study seasonal changes in aerosol parameters due to the influence of dust storms, anthropogenic pollution and biomass (crop residue) burning. MODIS derived deep blue AOD provided better representation of aerosol loading over north Africa (Sahara region) along with dark-target AOD and related parameters. AERONET data provided aerosol optical depth, angstrom, fine mode fraction, size fraction, volume, effective radius, refractive index, single scattering albedo, and radiative forcing during different seasons dominated by dust storms, anthropogenic pollution and biomass burning (black cloud phenomena). The results indicated that the observed AOD decreases in the summer and increases again in the fall due to agricultural burning events. Ground-based AERONET data support the "Dark Product" MODIS retrievals, as they typically show a fall peak in the 500 nm region. The number of dust distribution frequencies over Egypt has more frequency in the southeast and northwest of Egypt (5-7.5 days

  15. Classification of Aerosol Retrievals from Spaceborne Polarimetry Using a Multi-Parameter Algorithm

    NASA Astrophysics Data System (ADS)

    Russell, P. B.; Kacenelenbogen, M. S.; Livingston, J. M.; Hasekamp, O.; Burton, S. P.; Schuster, G. L.; Redemann, J.; Ramachandran, S.; Holben, B. N.

    2013-12-01

    In this presentation we demonstrate application of a new aerosol classification algorithm to retrievals from the POLDER-3 polarimeter on the PARASOL spacecraft. Motivation and method: Since the development of global aerosol measurements by satellites and AERONET, classification of observed aerosols into several types (e,g., urban-industrial, biomass burning, mineral dust, maritime, and various subtypes or mixtures of these) has proven useful to: understanding aerosol sources, transformations, effects, and feedback mechanisms; improving accuracy of satellite retrievals; and quantifying assessments of aerosol radiative impacts on climate. With ongoing improvements in satellite measurement capability, the number of aerosol parameters retrieved from spaceborne sensors has been growing, from the initial aerosol optical depth at one or a few wavelengths to a list that now includes complex refractive index, single scattering albedo (SSA), and depolarization of backscatter, each at several wavelengths; wavelength dependences of extinction, scattering, absorption, SSA, and backscatter; and several particle size and shape parameters. Making optimal use of these varied data products requires objective, multi-dimensional analysis methods. We describe such a method, which uses a modified Mahalanobis distance to quantify how far a data point described by N aerosol parameters is from each of several prespecified classes. The method makes explicit use of uncertainties in input parameters, treating a point and its N-dimensional uncertainty as an extended data point or pseudo-cluster E. It then uses a modified Mahalanobis distance, DEC, to assign that observation to the class (cluster) C that has minimum DEC from the point (equivalently, the class to which the point has maximum probability of belonging). The method also uses Wilks' overall lambda to indicate how well the input data lend themselves to separation into classes and Wilks' partial lambda to indicate the relative

  16. Estimation of aerosol optical depth at different wavelengths by multiple regression method.

    PubMed

    Tan, Fuyi; Lim, Hwee San; Abdullah, Khiruddin; Holben, Brent

    2016-02-01

    This study aims to investigate and establish a suitable model that can help to estimate aerosol optical depth (AOD) in order to monitor aerosol variations especially during non-retrieval time. The relationship between actual ground measurements (such as air pollution index, visibility, relative humidity, temperature, and pressure) and AOD obtained with a CIMEL sun photometer was determined through a series of statistical procedures to produce an AOD prediction model with reasonable accuracy. The AOD prediction model calibrated for each wavelength has a set of coefficients. The model was validated using a set of statistical tests. The validated model was then employed to calculate AOD at different wavelengths. The results show that the proposed model successfully predicted AOD at each studied wavelength ranging from 340 nm to 1020 nm. To illustrate the application of the model, the aerosol size determined using measure AOD data for Penang was compared with that determined using the model. This was done by examining the curvature in the ln [AOD]-ln [wavelength] plot. Consistency was obtained when it was concluded that Penang was dominated by fine mode aerosol in 2012 and 2013 using both measured and predicted AOD data. These results indicate that the proposed AOD prediction model using routine measurements as input is a promising tool for the regular monitoring of aerosol variation during non-retrieval time.

  17. Atmospheric aerosol characterization with a ground-based SPEX spectropolarimetric instrument

    NASA Astrophysics Data System (ADS)

    van Harten, G.; de Boer, J.; Rietjens, J. H. H.; Di Noia, A.; Snik, F.; Volten, H.; Smit, J. M.; Hasekamp, O. P.; Henzing, J. S.; Keller, C. U.

    2014-06-01

    Characterization of atmospheric aerosols is important for understanding their impact on health and climate. A wealth of aerosol parameters can be retrieved from multi-angle, multi-wavelength radiance and polarization measurements of the clear sky. We developed a ground-based SPEX instrument (groundSPEX) for accurate spectropolarimetry, based on the passive, robust, athermal and snapshot spectral polarization modulation technique, and hence ideal for field deployment. It samples the scattering phase function in the principal plane in an automated fashion, using a motorized pan/tilt unit and automatic exposure time detection. Extensive radiometric and polarimetric calibrations were performed, yielding values for both random noise and systematic uncertainties. The absolute polarimetric accuracy at low degrees of polarization is established to be ~ 5 × 10-3. About 70 measurement sequences have been performed throughout four clear-sky days at Cabauw, the Netherlands. Several aerosol parameters were retrieved: aerosol optical thickness, effective radius, and complex refractive index for fine and coarse mode. The results are in good agreement with the co-located AERONET products, with a correlation coefficient of ρ = 0.932 for the total aerosol optical thickness at 550 nm.

  18. Atmospheric aerosol characterization with a ground-based SPEX spectropolarimetric instrument

    NASA Astrophysics Data System (ADS)

    van Harten, G.; de Boer, J.; Rietjens, J. H. H.; Di Noia, A.; Snik, F.; Volten, H.; Smit, J. M.; Hasekamp, O. P.; Henzing, J. S.; Keller, C. U.

    2014-12-01

    Characterization of atmospheric aerosols is important for understanding their impact on health and climate. A wealth of aerosol parameters can be retrieved from multi-angle, multi-wavelength radiance and polarization measurements of the clear sky. We developed a ground-based SPEX instrument (groundSPEX) for accurate spectropolarimetry, based on the passive, robust, athermal, and snapshot spectral polarization modulation technique, and is hence ideal for field deployment. It samples the scattering phase function in the principal plane in an automated fashion, using a motorized pan/tilt unit and automatic exposure time detection. Extensive radiometric and polarimetric calibrations were performed, yielding values for both random noise and systematic uncertainties. The absolute polarimetric accuracy at low degrees of polarization is established to be ~5 × 10-3. About 70 measurement sequences have been performed throughout four clear-sky days at Cabauw, the Netherlands. Several aerosol parameters were retrieved: aerosol optical thickness, effective radius, and complex refractive index for fine and coarse mode. The results are in good agreement with the colocated AERONET products, with a correlation coefficient of ρ = 0.932 for the total aerosol optical thickness at 550 nm.

  19. Investigation of aerosol radiative forcing and atmosphere-ocean remote sensing in Northern Norway

    NASA Astrophysics Data System (ADS)

    Chen, Yi-Chun; Hamre, Børge; Stamnes, Snorre; Frette, Øyvind; Stamnes, Kunt; Stamnes, Jakob J.

    2013-04-01

    We examine aerosol optical properties and radiative forcing at Andenes, Northern Norway (69N, 16E, 379 m altitude) during a two-year period (2008-2010) using AERONET data, radiative transfer modelling (C-DISORT), and Mie-scattering computations. We show that the mean value of the aerosol optical thickness at 500 nm derived from AERONET measurements is close to that obtained from Mie-scattering computations with input of aerosol size distribution and refractive index as derived from AERONET measurements. Also, different models for the ground reflectance used as input to the radiative transfer computations are shown to have little impact on the aerosol radiative forcing both at the top and bottom of the atmosphere. The coupled atmosphere-surface system accounted for by C-DISORT is suitable for radiative transfer calculations over open ocean and coastal water areas, and we discuss how it can be used to make simultaneous retrieval of aerosol and marine parameters from ocean colour data.

  20. Systematic Relationships Between Lidar Observables and Sizes And Mineral Composition Of Dust Aerosols

    NASA Technical Reports Server (NTRS)

    Van Diedenhoven, Bastiaan; Stangl, Alexander; Perlwitz, Jan; Fridlind, Ann M.; Chowdhary, Jacek; Cairns, Brian

    2015-01-01

    The physical and chemical properties of soil dust aerosol particles fundamentally affect their interaction with climate, including shortwave absorption and radiative forcing, nucleation of cloud droplets and ice crystals, heterogeneous formation of sulfates and nitrates on the surface of dust particles, and atmospheric processing of iron into bioavailable forms that increase the productivity of marine phytoplankton. Lidar measurements, such as extinction-to-backscatter, color and depolarization ratios, are frequently used to distinguish between aerosol types with different physical and chemical properties. The chemical composition of aerosol particles determines their complex refractive index, hence affecting their backscattering properties. Here we present a study on how dust aerosol backscattering and depolarization properties at wavelengths of 355, 532 and 1064 nm are related to size and complex refractive index, which varies with the mineral composition of the dust. Dust aerosols are represented by collections of spheroids with a range of prolate and oblate aspect ratios and their optical properties are obtained using T-matrix calculations. We find simple, systematic relationships between lidar observables and the dust size and complex refractive index that may aid the use of space-based or airborne lidars for direct retrieval of dust properties or for the evaluation of chemical transport models using forward simulated lidar variables. In addition, we present first results on the spatial variation of forward-simulated lidar variables based on a dust model that accounts for the atmospheric cycle of eight different mineral types plus internal mixtures of seven mineral types with iron oxides, which was recently implemented in the NASA GISS Earth System ModelE2.

  1. Utilization of AERONET polarimetric measurements for improving retrieval of aerosol microphysics: GSFC, Beijing and Dakar data analysis

    NASA Astrophysics Data System (ADS)

    Fedarenka, Anton; Dubovik, Oleg; Goloub, Philippe; Li, Zhengqiang; Lapyonok, Tatyana; Litvinov, Pavel; Barel, Luc; Gonzalez, Louis; Podvin, Thierry; Crozel, Didier

    2016-08-01

    The study presents the efforts on including the polarimetric data to the routine inversion of the radiometric ground-based measurements for characterization of the atmospheric aerosols and analysis of the obtained advantages in retrieval results. First, to operationally process the large amount of polarimetric data the data preparation tool was developed. The AERONET inversion code adapted for inversion of both intensity and polarization measurements was used for processing. Second, in order to estimate the effect from utilization of polarimetric information on aerosol retrieval results, both synthetic data and the real measurements were processed using developed routine and analyzed. The sensitivity study has been carried out using simulated data based on three main aerosol models: desert dust, urban industrial and urban clean aerosols. The test investigated the effects of utilization of polarization data in the presence of random noise, bias in measurements of optical thickness and angular pointing shift. The results demonstrate the advantage of polarization data utilization in the cases of aerosols with pronounced concentration of fine particles. Further, the extended set of AERONET observations was processed. The data for three sites have been used: GSFC, USA (clean urban aerosol dominated by fine particles), Beijing, China (polluted industrial aerosol characterized by pronounced mixture of both fine and coarse modes) and Dakar, Senegal (desert dust dominated by coarse particles). The results revealed considerable advantage of polarimetric data applying for characterizing fine mode dominated aerosols including industrial pollution (Beijing). The use of polarization corrects particle size distribution by decreasing overestimated fine mode and increasing the coarse mode. It also increases underestimated real part of the refractive index and improves the retrieval of the fraction of spherical particles due to high sensitivity of polarization to particle shape

  2. Characterization of aerosol episodes in the greater Mediterranean Sea area from satellite observations (2000-2007)

    NASA Astrophysics Data System (ADS)

    Gkikas, A.; Hatzianastassiou, N.; Mihalopoulos, N.; Torres, O.

    2016-03-01

    An algorithm able to identify and characterize episodes of different aerosol types above sea surfaces of the greater Mediterranean basin (GMB), including the Black Sea and the Atlantic Ocean off the coasts of Iberia and northwest Africa, is presented in this study. Based on this algorithm, five types of intense (strong and extreme) aerosol episodes in the GMB are identified and characterized using daily aerosol optical properties from satellite measurements, namely MODIS-Terra, Earth Probe (EP)-TOMS and OMI-Aura. These aerosol episodes are: (i) biomass-burning/urban-industrial (BU), (ii) desert dust (DD), (iii) dust/sea-salt (DSS), (iv) mixed (MX) and (v) undetermined (UN). The identification and characterization is made with our algorithm using a variety of aerosol properties, namely aerosol optical depth (AOD), Ångström exponent (α), fine fraction (FF), effective radius (reff) and Aerosol Index (AI). During the study period (2000-2007), the most frequent aerosol episodes are DD, observed primarily in the western and central Mediterranean Sea, and off the northern African coasts, 7 times/year for strong episodes and 4 times/year for extreme ones, on average. The DD episodes yield 40% of all types of strong aerosol episodes in the study region, while they account for 71.5% of all extreme episodes. The frequency of occurrence of strong episodes exhibits specific geographical patterns, for example the BU are mostly observed along the coasts of southern Europe and off the Atlantic coasts of Portugal, the MX episodes off the Spanish Mediterranean coast and over the Adriatic and northern Aegean Sea, while the DSS ones over the western and central Mediterranean Sea. On the other hand, the extreme episodes for all but DD aerosol display more patchy spatial patterns. The strong episodes exhibit AOD at 550 nm as high as 1.6 in the southernmost parts of central and eastern Mediterranean Sea, which rise up to 5 for the extreme, mainly DD and DSS, episodes. Although more

  3. NASA 1981 photography index

    NASA Technical Reports Server (NTRS)

    1982-01-01

    An index of representative photographs is presented. Color transparencies and black and white glossies of major launches, Mariner spacecraft, Pioneer spacecraft, planets and other space phenomena, Skylab, space shuttle, Viking spacecraft, and Voyager spacecraft are included.

  4. Pesticide Use Site Index

    EPA Pesticide Factsheets

    The Pesticide Use Site Index will help a company (or other applicant) identify which data requirements are needed to register a pesticide product. It provides information on pesticide use sites and pesticide major use patterns.

  5. Aerosol Blanket Likely Thinned During 1990s

    NASA Technical Reports Server (NTRS)

    2007-01-01

    Each day, a blanket of tiny particles drifting through the Earth's atmosphere filters out some of the sunlight headed for the planet's surface. These aerosols, including dust, smoke, and human-produced pollution, can reflect incoming light or absorb it, directly affecting the Earth's energy balance and climate. Aerosols also influence the climate indirectly, by affecting the brightness and amount of clouds. Research by NASA scientists on global aerosol patterns since the 1990s indicate the global aerosol blanket has likely thinned, allowing more sunlight to reach the Earth's surface over the past decade. The thinning of the blanket is shown by this trio of images based on satellite observations of aerosol optical thickness, a measurement that scientists use to describe how much the aerosols filter the incoming sunlight. Higher optical thickness (orange and red) means more sunlight blocking. The globes show average aerosol optical thickness for 1988-1991 (top), 2002-2005 (middle), and the change between the two time periods (bottom). Overall, the 1988-1991 image appears redder, a sign that aerosols were blocking more incoming sunlight; the 2002-2005 image has more light yellow areas. In the bottom image, small pockets of red (increased aerosol optical thickness), mostly near land masses in the Northern Hemisphere, are far outnumbered by blue areas (decreased aerosol optical thickness). Because they block incoming sunlight from reaching Earth's surface, aerosols may counterbalance greenhouse gas warming. The decline in the dimming power of aerosols over the past decade may have made the greenhouse warming trend more evident in the past decade than in previous decades. The scientists describe their results as a 'likely' trend because the National Oceanic and Atmospheric Administration satellite sensors they used in their analysis were not specifically designed to observe aerosols, and may contain some errors. However, specific, major aerosol events, such as large

  6. Heterogeneous Chemistry: Understanding Aerosol/Oxidant Interactions

    SciTech Connect

    Joyce E. Penner

    2005-03-14

    Global radiative forcing of nitrate and ammonium aerosols has mostly been estimated from aerosol concentrations calculated at thermodynamic equilibrium or using approximate treatments for their uptake by aerosols. In this study, a more accurate hybrid dynamical approach (DYN) was used to simulate the uptake of nitrate and ammonium by aerosols and the interaction with tropospheric reactive nitrogen chemistry in a three-dimensional global aerosol and chemistry model, IMPACT, which also treats sulfate, sea salt and mineral dust aerosol. 43% of the global annual average nitrate aerosol burden, 0.16 TgN, and 92% of the global annual average ammonium aerosol burden, 0.29 TgN, exist in the fine mode (D<1.25 {micro}m) that scatters most efficiently. Results from an equilibrium calculation differ significantly from those of DYN since the fraction of fine-mode nitrate to total nitrate (gas plus aerosol) is 9.8%, compared to 13% in DYN. Our results suggest that the estimates of aerosol forcing from equilibrium concentrations will be underestimated. We also show that two common approaches used to treat nitrate and ammonium in aerosol in global models, including the first-order gas-to-particle approximation based on uptake coefficients (UPTAKE) and a hybrid method that combines the former with an equilibrium model (HYB), significantly overpredict the nitrate uptake by aerosols especially that by coarse particles, resulting in total nitrate aerosol burdens higher than that in DYN by +106% and +47%, respectively. Thus, nitrate aerosol in the coarse mode calculated by HYB is 0.18 Tg N, a factor of 2 more than that in DYN (0.086 Tg N). Excessive formation of the coarse-mode nitrate in HYB leads to near surface nitrate concentrations in the fine mode lower than that in DYN by up to 50% over continents. In addition, near-surface HNO{sub 3} and NO{sub x} concentrations are underpredicted by HYB by up to 90% and 5%, respectively. UPTAKE overpredicts the NO{sub x} burden by 56% and near

  7. Gradient Index Lens Research.

    DTIC Science & Technology

    1982-11-25

    over six to nine readings at two to three input polarizations each. The first set of index values is calculated assuming ei = 450 These values are...TECHNICAL REPORT RG-CR-84-2 Sli GRADIENT INDEX LENS RESEARCH Prepared by: Duncan T. Moore The Institute of Optics University of Rochester Rochester...CLASSIFICATION OF THIS PAGE (Miten Data Fntered) READ INSTRUCTIONSREPORT DOCUMENTATION PAGE BEFORE COMPLETING FORM 1. REPORT NU14MU R GOVT ACCESSION No. 3

  8. JSC document index

    NASA Technical Reports Server (NTRS)

    1988-01-01

    The Johnson Space Center (JSC) document index is intended to provide a single source listing of all published JSC-numbered documents their authors, and the designated offices of prime responsibility (OPR's) by mail code at the time of publication. The index contains documents which have been received and processed by the JSC Technical Library as of January 13, 1988. Other JSC-numbered documents which are controlled but not available through the JSC Library are also listed.

  9. Seasonality of Aerosols the Southeastern United States

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  10. Characterization of aerosols produced by surgical procedures

    SciTech Connect

    Yeh, H.C.; Muggenburg, B.A.; Lundgren, D.L.; Guilmette, R.A.; Snipes, M.B.; Jones, R.K.; Turner, R.S.

    1994-07-01

    In many surgeries, especially orthopedic procedures, power tools such as saws and drills are used. These tools may produce aerosolized blood and other biological material from bone and soft tissues. Surgical lasers and electrocautery tools can also produce aerosols when tissues are vaporized and condensed. Studies have been reported in the literature concerning production of aerosols during surgery, and some of these aerosols may contain infectious material. Garden et al. (1988) reported the presence of papilloma virus DNA in the fumes produced from laser surgery, but the infectivity of the aerosol was not assessed. Moon and Nininger (1989) measured the size distribution and production rate of emissions from laser surgery and found that particles were generally less than 0.5 {mu}m diameter. More recently there has been concern expressed over the production of aerosolized blood during surgical procedures that require power tools. In an in vitro study, the production of an aerosol containing the human immunodeficiency virus (HIV) was reported when power tools were used to cut tissues with blood infected with HIV. Another study measured the size distribution of blood aerosols produced by surgical power tools and found blood-containing particles in a number of size ranges. Health care workers are anxious and concerned about whether surgically produced aerosols are inspirable and can contain viable pathogens such as HIV. Other pathogens such as hepatitis B virus (HBV) are also of concern. The Occupational Safety and Health funded a project at the National Institute for Inhalation Toxicology Research Institute to assess the extent of aerosolization of blood and other tissues during surgical procedures. This document reports details of the experimental and sampling approach, methods, analyses, and results on potential production of blood-associated aerosols from surgical procedures in the laboratory and in the hospital surgical suite.

  11. New generic indexing technology

    NASA Technical Reports Server (NTRS)

    Freeston, Michael

    1996-01-01

    There has been no fundamental change in the dynamic indexing methods supporting database systems since the invention of the B-tree twenty-five years ago. And yet the whole classical approach to dynamic database indexing has long since become inappropriate and increasingly inadequate. We are moving rapidly from the conventional one-dimensional world of fixed-structure text and numbers to a multi-dimensional world of variable structures, objects and images, in space and time. But, even before leaving the confines of conventional database indexing, the situation is highly unsatisfactory. In fact, our research has led us to question the basic assumptions of conventional database indexing. We have spent the past ten years studying the properties of multi-dimensional indexing methods, and in this paper we draw the strands of a number of developments together - some quite old, some very new, to show how we now have the basis for a new generic indexing technology for the next generation of database systems.

  12. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass Aerosol Extinction Differential Optical Absorption Spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2012-04-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  13. Initial investigation of the wavelength dependence of optical properties measured with a new multi-pass aerosol extinction differential optical absorption spectrometer (AE-DOAS)

    NASA Astrophysics Data System (ADS)

    Chartier, R. T.; Greenslade, M. E.

    2011-10-01

    Atmospheric aerosols directly affect climate by scattering and absorbing radiation. The magnitude of the impact is dependent upon the wavelength of light, but is often estimated near 550 nm. When light scattering and absorption by aerosols is approximated, the wavelength dependence of the refractive index for specific components is lost. As a result, climate models would have inherent uncertainties for aerosol contributions to radiative forcing when considering the entire solar spectrum. An aerosol extinction differential optical absorption spectrometer has been developed to directly measure aerosol extinction at mid-ultraviolet to near infrared wavelengths. The instrument consists of a spectrometer coupled to a closed White-type multi-pass gas cell with an adjustable path length of up to approximately 20 m. Laboratory measurements of various gases are compared with known absorption cross sections. Additionally, the extinction of monodisperse samples of polystyrene latex spheres are measured and compared to Mie theory generated with refractive index values from the literature to validate the new instrument. The polystyrene experiments also emphasize the ability of the new instrument to retrieve the wavelength dependent refractive index, especially in the ultraviolet wavelength regions where variability is expected. The spectrometer will be a significant advancement for determining wavelength dependent complex refractive indices in future laboratory studies as well as provide the ability to monitor ambient aerosol light extinction.

  14. Aerosol retrieval algorithm for the characterization of local aerosol using MODIS L1B data

    NASA Astrophysics Data System (ADS)

    Wahab, A. M.; Sarker, M. L. R.

    2014-02-01

    Atmospheric aerosol plays an important role in radiation budget, climate change, hydrology and visibility. However, it has immense effect on the air quality, especially in densely populated areas where high concentration of aerosol is associated with premature death and the decrease of life expectancy. Therefore, an accurate estimation of aerosol with spatial distribution is essential, and satellite data has increasingly been used to estimate aerosol optical depth (AOD). Aerosol product (AOD) from Moderate Resolution Imaging Spectroradiometer (MODIS) data is available at global scale but problems arise due to low spatial resolution, time-lag availability of AOD product as well as the use of generalized aerosol models in retrieval algorithm instead of local aerosol models. This study focuses on the aerosol retrieval algorithm for the characterization of local aerosol in Hong Kong for a long period of time (2006-2011) using high spatial resolution MODIS level 1B data (500 m resolution) and taking into account the local aerosol models. Two methods (dark dense vegetation and MODIS land surface reflectance product) were used for the estimation of the surface reflectance over land and Santa Barbara DISORT Radiative Transfer (SBDART) code was used to construct LUTs for calculating the aerosol reflectance as a function of AOD. Results indicate that AOD can be estimated at the local scale from high resolution MODIS data, and the obtained accuracy (ca. 87%) is very much comparable with the accuracy obtained from other studies (80%-95%) for AOD estimation.

  15. Water absorption by secondary organic aerosol and its effect on inorganic aerosol behavior

    SciTech Connect

    Ansari, A.S.; Pandis, S.N.

    2000-01-01

    The hygroscopic nature of atmospheric aerosol has generally been associated with its inorganic fraction. In this study, a group contribution method is used to predict the water absorption of secondary organic aerosol (SOA). Compared against growth measurements of mixed inorganic-organic particles, this method appears to provide a first-order approximation in predicting SOA water absorption. The growth of common SOA species is predicted to be significantly less than common atmospheric inorganic salts such as (NH{sub 4}){sub 2}SO{sub 4} and NaCl. Using this group contribution method as a tool in predicting SOA water absorption, an integrated modeling approach is developed combining available SOA and inorganic aerosol models to predict overall aerosol behavior. The effect of SOA on water absorption and nitrate partitioning between the gas and aerosol phases is determined. On average, it appears that SOA accounts for approximately 7% of total aerosol water and increases aerosol nitrate concentrations by approximately 10%. At high relative humidity and low SOA mass fractions, the role of SOA in nitrate partitioning and its contribution to total aerosol water is negligible. However, the water absorption of SOA appears to be less sensitive to changes in relative humidity than that of inorganic species, and thus at low relative humidity and high SOA mass fraction concentrations, SOA is predicted to account for approximately 20% of total aerosol water and a 50% increase in aerosol nitrate concentrations. These findings could improve the results of modeling studies where aerosol nitrate has often been underpredicted.

  16. Aerosol polarization effects on atmospheric correction and aerosol retrievals in ocean color remote sensing.

    PubMed

    Wang, Menghua

    2006-12-10

    The current ocean color data processing system for the Sea-viewing Wide Field-of-View Sensor (SeaWiFS) and the moderate resolution imaging spectroradiometer (MODIS) uses the Rayleigh lookup tables that were generated using the vector radiative transfer theory with inclusion of the polarization effects. The polarization effects, however, are not accounted for in the aerosol lookup tables for the ocean color data processing. I describe a study of the aerosol polarization effects on the atmospheric correction and aerosol retrieval algorithms in the ocean color remote sensing. Using an efficient method for the multiple vector radiative transfer computations, aerosol lookup tables that include polarization effects are generated. Simulations have been carried out to evaluate the aerosol polarization effects on the derived ocean color and aerosol products for all possible solar-sensor geometries and the various aerosol optical properties. Furthermore, the new aerosol lookup tables have been implemented in the SeaWiFS data processing system and extensively tested and evaluated with SeaWiFS regional and global measurements. Results show that in open oceans (maritime environment), the aerosol polarization effects on the ocean color and aerosol products are usually negligible, while there are some noticeable effects on the derived products in the coastal regions with nonmaritime aerosols.

  17. Remote sensing of aerosol in the terrestrial atmosphere from space: "AEROSOL-UA" mission

    NASA Astrophysics Data System (ADS)

    Yatskiv, Yaroslav; Milinevsky, Gennadi; Degtyarev, Alexander

    2016-07-01

    The distribution and properties of atmospheric aerosols on a global scale are not well known in terms of determination of their effects on climate. This mostly is due to extreme variability of aerosol concentrations, properties, sources, and types. Aerosol climate impact is comparable to the effect of greenhouse gases, but its influence is more difficult to measure, especially with respect to aerosol microphysical properties and the evaluation of anthropogenic aerosol effect. There are many satellite missions studying aerosol distribution in the terrestrial atmosphere, such as MISR/Terra, OMI/Aura, AVHHR, MODIS/Terra and Aqua, CALIOP/CALIPSO. To improve the quality of data and climate models, and to reduce aerosol climate forcing uncertainties, several new missions are planned. The gap in orbital instruments for studying aerosol microphysics has arisen after the Glory mission failed during launch in 2011. In this review paper, we describe several planned aerosol space missions, including the Ukrainian project AEROSOL-UA that will obtain the data using a multi-channel scanning polarimeter and wide-angle polarimetric camera. The mission is designed for remote sensing of the aerosol microphysics and cloud properties on a global scale.

  18. Aerosol and cloud relations and weekly cycles over Central Europe

    NASA Astrophysics Data System (ADS)

    Kourtidis, K.; Georgoulias, A.; Alexandri, G.

    2012-04-01

    In this work, the aerosol and cloud relationships and weekly cycle patterns over Central Europe are examined using level-2 aerosol data from the TERRA MODIS satellite instrument to compile a decadal (2000-2010) 0.1 x 0.1 degree resolution gridded dataset as well as and total cloud cover (TCC) TERRA MODIS data and coarser resolution ISCCP TCC data. Aerosols and TCC were found to be positively correlated for all seasons, the slope of the correlation being slightly higher for low AOD values. A co-examination of AOD, TCC and NCAR/NCEP sea level pressure shows that the positive AOD-TCC correlation holds separately in all pressure bins, thus indicating that the correlation is not a synoptic artefact. A study of the weekly cycle of AOD shows that the main part of the positive (i.e. with midweek peak) weekly cycle plume extends over the central part of Central Europe, with the weekly cycle index (WCI) levels gradually decreasing until the weekly cycle becomes negative (i.e. with weekend peak) when moving away. No clear connection between the WCI patterns and topography was found while there is an apparent correlation between positive weekly cycles in summer and population density. A clear Monday minimum appears over regions with high positive WCI. Monday shifts to Tuesday when moving to the East, indicating aerosol transport from the dominating westerly wind flow. The WCI values and the average percent departures (APDs) for the day of weekly maximum and minimum were examined for 22 selected stations from previous ground-based weekly cycle studies. The weekly cycle is positive and statistically significant for only a few stations situated in France, Germany, Czech Republic and Belgium. A comparison with 1 x 1 degree level-3 MODIS TERRA data shows that in most cases level-3 data can give an indication of the local aerosol weekly cycle strength and phase. The satellite derived day of the weekly maximum and minimum is, generally, in line with results from ground-based studies

  19. Thermal Infrared Radiative Forcing By Atmospheric Aerosol

    NASA Astrophysics Data System (ADS)

    Adhikari, Narayan

    The work mainly focuses on the study of thermal infrared (IR) properties of atmospheric greenhouse gases and aerosols, and the estimation of the aerosol-induced direct longwave (LW) radiative forcing in the spectral region 5-20 mum at the Earth's surface (BOA; bottom of the atmosphere) and the top of the atmosphere (TOA) in cloud-free atmospheric conditions. These objectives were accomplished by conducting case studies on clear sky, smoky, and dusty conditions that took place in the Great Basin of the USA in 2013. Both the solar and thermal IR measurements and a state-of-the-science radiative transfer model, the LBLDIS, a combination of the Line-By-Line Radiative Transfer Model and the Discrete Ordinate Radiative Transfer (DISORT) solver were employed for the study. The LW aerosol forcing is often not included in climate models because the aerosol effect on the LW is often assumed to be negligible. We lack knowledge of aerosol characteristics in the LW region, and aerosol properties exhibit high variability. We have found that the LW TOA radiative forcing due to fine mode aerosols, mainly associated with small biomass burning smoke particles, is + 0.4 W/m2 which seems to be small, but it is similar to the LW radiative forcing due to increase in CO2 concentration in the Earth's atmosphere since the preindustrial era of 1750 (+ 1.6 W/m 2). The LW radiative forcing due to coarse mode aerosols, associated with large airborne mineral dust particles, was found to be as much as + 5.02 W/m2 at the surface and + 1.71 W/m2 at the TOA. All of these significant positive values of the aerosol radiative forcing both at the BOA and TOA indicate that the aerosols have a heating effect in the LW range, which contributes to counterbalancing the cooling effect associated with the aerosol radiative forcing in the shortwave (SW) spectral region. In the meantime, we have found that LW radiative forcing by aerosols is highly sensitive to particle size and complex refractive indices of

  20. Remote Sensing of Aerosol and Aerosol Radiative Forcing of Climate from EOS Terra MODIS Instrument

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram; Tanre, Didier; Remer, Lorraine; Einaudi, Franco (Technical Monitor)

    2000-01-01

    The recent launch of EOS-Terra into polar orbit has begun to revolutionize remote sensing of aerosol and their effect on climate. Terra has five instruments, two of them,Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging Spectro-Radiometer (MISR) are designed to monitor global aerosol in two different complementary ways. Here we shall discuss the use of the multispectral measurements of MODIS to derive: (1) the global distribution of aerosol load (and optical thickness) over ocean and land; (2) to measure the impact of aerosol on reflection of sunlight to space; and (3) to measure the ability of aerosol to absorb solar radiation. These measurements have direct applications on the understanding of the effect of aerosol on climate, the ability to predict climate change, and on the monitoring of dust episodes and man-made pollution. Principles of remote sensing of aerosol from MODIS will be discussed and first examples of measurements from MODIS will be provided.

  1. Effects of aerosol organics on cloud condensation nucleus (CCN) concentration and first indirect aerosol effect

    SciTech Connect

    Wang, J. X.; Lee, Y.- N.; Daum, Peter H.; Jayne, John T.; Alexander, M. L.

    2008-11-03

    Abstract. Aerosol microphysics, chemical composition, and CCN properties were measured on the Department of Energy Gulfstream-1 aircraft during the Marine Stratus/ Stratocumulus Experiment (MASE) conducted over the coastal waters between Point Reyes National Seashore and Monterey Bay, California, in July 2005. Aerosols measured during MASE included free tropospheric aerosols, marine boundary layer aerosols, and aerosols with high organic concentration within a thin layer above the cloud. Closure analysis was carried out for all three types of aerosols by comparing the measured CCN concentrations at 0.2% supersaturation to those predicted based on size distribution and chemical composition using K¨ohler theory. The effect of aerosol organic species on predicted CCN concentration was examined using a single hygroscopicity parameterization.

  2. Retrievals of Aerosol and Cloud Particle Microphysics Using Polarization and Depolarization Techniques

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael; Hansen, James E. (Technical Monitor)

    2001-01-01

    The recent availability of theoretical techniques for computing single and multiple scattering of light by realistic polydispersions of spherical a