A33C-1398
Local CO enhancements in the upper troposphere: examining data from TES, MLS and MOPITT
We focus on selected CO enhancement events observed in TES data and also examine MLS and MOPITT data in the upper and lower troposphere. The events of interest include: the Siberian fires in July-Aug 2006, Indonesian fires in Sept-Oct-Nov 2006, Australian fires in mid-end Dec 2006 and the transpacific transports of pollutants in winter-spring 2007. The CO distributions near the event regions observed by the three instruments provide good opportunities for cross-instrument and cross-platform validations of the datasets. We describe the advantages, the limitations and the influence of the a priori assumptions to the retrievals for the nadir and limb instruments. The combination of the nadir and limb observations of CO provides a powerful datasets for studying pollution transport in different regions of the globe. Trajectory models are used to track the origins of the enhanced CO at different levels of the troposphere.
A33C-1399
Particulate Matter Air Quality Assessment in EPA Region 4 Using Multi Year Satellite and Ground Based Measurements
Particulate matter air quality monitoring and forecasting using remote sensing observations has been a developing area of research over the last several years. Excessive air pollution due to small suspended particles is an environmental crisis of worldwide concern. Aerosol loading in an atmospheric column is estimated by retrieving aerosol optical thickness (AOT) from polar orbiting and geostationary satellites. These AOT values are inter-compared with coincident PM2.5 mass concentrations measured from surface stations. These AOT-PM2.5 relationships can then be used to obtain PM2.5 mass concentrations at those locations where surface measurements are not available. Hence, satellite data can be used to monitor global air pollution on an almost daily basis. In our current study we used seven years of surface and satellite data over several locations in EPA region 4 to derive these relationships. We also discuss the uncertainties associated with using satellite derived PM2.5 mass due to cloud and other sampling issues in satellite measurements. Specific case studies from the Georgia/Florida 2007 biomass burning and Spring biomass burning in Central America will also be presented.
A33C-1400
Validation of OMI Tropospheric Nitrogen Dioxide Column Data Using MAX-DOAS Measurements Deep Inside the North China Plain in June 2006
A challenge for the quantitative analysis of tropospheric nitrogen dioxide (NO2) column data from satellite observations is likely posed mainly by the lack of satellite-independent observations for validation. We performed such satellite-independent observations of the tropospheric NO2 column using the ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) technique in the North China Plain (NCP) from 29 May to 29 June, 2006. Comparisons between tropospheric NO2 columns measured by MAX-DOAS and the Ozone Monitoring Instrument (OMI) onboard the Aura satellite indicate that OMI data over NCP likely have a positive bias of 2×1015 molecules cm-2 (~30%), but it is within the estimated random error of 3×1015 molecules cm-2 (~40%). Considering the uncertainty estimated here will pave the way for quantitative studies using the OMI NO2 data over NCP.
A33C-1401
Aerosol and Plume Height Measurements from Satellites for Air Quality Studies
Satellite measurements of aerosols and aerosol characteristics from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and the Multi-angle Imaging SpectroRadiometer (MISR) instruments are available on global and regional scales. These measurements are essential for air quality research and applications. Example applications of CALIPSO and MISR data products for air quality studies will be presented. CALIPSO provides new insights into aerosol abundance, size and layers, including volcanic emissions, dust storms, clouds, and pollution events with measurements from three instruments, Cloud-Aerosol LIdar with Orthogonal Polarization, Imaging Infrared Radiometer, and Wide Field Camera. MISR collects multi-angle as well as multi-spectral data never before obtained by satellite instruments. The additional information contained in these data make it possible to obtain aerosol amount, particle size and composition, as well as plume heights. The Atmospheric Science Data Center (ASDC) in Langley's Science Directorate leads NASA's program for the processing, archival and distribution of Earth science data in the areas of radiation budget, clouds, aerosols, and tropospheric chemistry. The Data Center was established in 1991 to support NASA's Earth Observing System and the U.S. Global Change Research Program. It is unique among NASA data centers in the size of its archive, cutting edge computing technology, and full range of data services. Additional information about all ASDC data products, images and tools is available from the ASDC web site, http://eosweb.larc.nasa.gov. http://eosweb.larc.nasa.gov
A33C-1402
TES Observations of Enhanced Ammonia & Methanol Over Northeast Asia
The Tropospheric Emission Spectrometer (TES) on the EOS Aura satellite makes global measurements of infrared radiances that are used to derive profiles of species such as O3, CO, H2O and CH4 as routine standard products. In addition, TES has a variety of special modes that provide denser spatial mapping at the expense of reduced coverage. One of these modes (called "transect") has now been used to detect additional molecules indicative of regional air pollution. On July 10 2007 at about 05:37 UTC (13:24 LMST) TES conducted such a transect observation over northeast Asia between latitudes +37.988 & +41.998, east longitudes 117.014 & 115.746 (some 460 km long). Examination of the spectral residuals (observed – calculated) following the retrieval of the TES standard products revealed surprisingly strong features attributable to enhanced concentrations of ammonia (NH3) and methanol (CH3OH), well above the normal background levels. This is the first time that these molecules have been detected in nadir viewing measurements that penetrate into the lower atmosphere. The paper will discuss the concentration and distribution of these species over this area and offer suggestions as to their origin. This work was carried out, in part, at the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, under contract with the National Aeronautics and Space Administration.
A33C-1403
Optimally combining ozone from Tropospheric Emission Spectrometer (TES) and Ozone Monitoring Instrument (OMI) data
We show results from joint TES-OMI ozone retrievals for May, 2006. We combine TES and OMI data using both optimal averaging of the individual profile retrieval results from OMI and TES, and by linear updates from the spectral residuals. Combined retrievals from the UV and IR spectral ranges have previously been shown to result in increased tropospheric sensitivity and resolution, and of particular interest, increased sensitivity to the planetary boundary layer. Results are compared to the OMI and TES results, and to near by sondes.
A33C-1404
Regional Air Quality Studies Using MOPITT CO Data : A Case Study of Linfen City and the Wei River Valley in China
MOPITT measures atmospheric CO using thermal channel at 4.7 μm and as such is mostly sensitive to the middle and the upper troposphere. However a recent assessment of the MOPITT averaging kernels after normalizing for non-uniform grid effects indicates that over land areas with sparse vegetation during daytime, MOPITT may have sensitivity to CO in the boundary layer. Thus it may be possible to use the MOPITT data for regional air quality studies. In particular, China with its strong emission sources and varying topography makes for an interesting area to test this. We present a case study over the Wei river valley in northern China. Linfen, ranked consistently as one of the most polluted cities globally, is located on the east bank of Fen river north east of the Wei river valley. We find that a strong CO plume associated with Linfen is clearly delineated in monthly average maps of CO mixing ratio at 850 hPa for all months when data are available. High CO mixing ratios often exceeding 300 ppbv at 850 hPa are observed near Linfen and are likely resulting from the coal based industries in the city. Further, regionally enhanced CO aligned with the Wei river valley suggests topographic effects. These features seen in MOPITT CO data are correlated with corresponding signatures of Linfen city and the Wei river valley in SCIAMACHY NO2 tropospheric column data, which indicates that MOPITT low altitude retrievals are capturing the source regions. Seasonal variation of CO and NO2 around Linfen city, as seen in the satellite data will be discussed. The topographic signature along the Wei river valley can also be seen in other datasets like Aura OMI NO2 tropospheric column and MODIS aerosol optical depth.
A33C-1405
Estimation of ground-level PM2.5 and PM10 using MODIS aerosol optical observations over East Asia
Aerosols from both anthropogenic and natural sources play a significant role in the atmosphere because their variation influences radiation, atmospheric stability, cloud, and precipitation on a time scale of from few days to decades. Recent studies manifest their impact on the atmosphere in East Asia due to rapid growth in economy, however our understanding of aerosols including spatial and temporal variations, sources, and chemical compositions over East Asia remain unclear. Here we employ a method to estimate ground-level PM2.5 and PM10 over East Asia by applying local scaling factors from a global chemical transport model (GEOS-Chem) to a combination of aerosol optical thickness and fine mode fraction measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument for 2001. Aerosol concentrations for individual chemical species in the GEOS-Chem are validated with observations from the Transport and Chemical Evolution over the Pacific (TRACE- P) and the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) aircraft campaigns in spring 2001. Our analysis shows the reliable extent in the spatial and temporal patterns of the estimated PM2.5 and PM10 concentrations. Contributions of individual aerosol species to the estimated PM2.5 and PM10 mass concentrations on the basis of the GEOS-Chem simulation are consistent with a few chemical observations of PM2.5 in surface air over East Asia. Our estimates could be employed for future studies to investigate the role of aerosols in atmospheric processes such as the upper-layer cloud and raindrop formation, the atmospheric stability and circulation, and the regional climate in East Asia.
A33C-1406
Satellite retrieved aerosol extinction coefficients for sensor performance in the coastal zone
Littoral characterization and sensor performance assist in optimizing the efficiency and safety of operations in the area. The environmental conditions of the marine boundary layer (MBL) – due to weather and atmospheric effects – change continuously in space and time, which certainly holds for the aerosol make-up. Models have been developed to describe the electro-optical propagation in the boundary layer as a function of meteorological parameters. EOSTAR is such an end-to-end model suite for electro-optical sensor performance in which the Advanced Navy Aerosol Model (ANAM) is embedded for computing the aerosol extinction. While ANAM provides favourable results in open ocean conditions, in coastal zones the model lacks accuracy due to the presence of aerosols from a variety of sources that need to be assessed. In offshore wind conditions continental aerosols of anthropogenic and natural origin mix with marine aerosols produced in the surf zone and by wave breaking further offshore. Radiometers on satellites can be used to retrieve the spatial variation over an extended area determined by the swath width, with a resolution determined by the radiometer pixel size. More accurate information on the aerosol properties in larger coastal domains are required to correctly handle the aerosol influence on transmission characteristics in the coastal zone. Results from in situ measurements off the coast of Italy in April 2007 are presented in this analysis. For one particular day, the satellite retrieved aerosol optical thickness (AOT) is to be compared with hand-held sun photometer measurements for quality assessment. The AOT values are converted into aerosol extinction coefficients for a pre-defined path. For one visible wavelength channel the transmission loss is computed with these coefficients, which is compared with the computed transmission loss for the path in case of a) a single extinction coefficient obtained from measurements and b) a modeled extinction coefficient obtained from ANAM.
A33C-1407
Formaldehyde (HCHO) Satellite Measurements in Shipping Emissions.
We present a case study of the first satellite measurements of formaldehyde (HCHO) from shipping emissions, derived from observations made by the GOME instrument. Launched on the ERS-2 satellite in April 1995, GOME has performed continuous operations over 8 years providing global observations of different trace gases. In this way, satellite observations provide unique opportunities for the identifications of trace gas sources. Previous studies on NO2 emissions from shipping (Beirle et al., 2004; Richter et al., 2004) and model studies of emissions from international shipping (Eyring et al., 2007) have highlighted the importance of ship exhausts for the marine boundary layer. We analyzed enhanced HCHO tropospheric columns from shipping emissions over the Indian Ocean between Sri Lanka and Sumatra. This region offers good conditions for plume detection with the GOME instrument as all ship tracks follow a single narrow track in the same east-west direction than used for the GOME pixel scanning. From the observed HCHO column densities we estimate the direct and indirect HCHO emissions from shipping. The results obtained using GOME data are further confirmed by comparison with HCHO columns from SCIAMACHY, which has higher detection limits for formaldehyde but provides better spatial resolution.
A33C-1408
Observations of local and regional ozone and carbon monoxide over Asia from the Tropospheric Ozone Spectrometer
TES observations of carbon monoxide and ozone were taken over Asia from July-August 2007 at both local and regional scales. We show elevated ozone and carbon monoxide concentrations in the lower troposphere that exceed 150 ppb near pollution centers. We examine the circulation of the elevated quantities and its relationship to local-regional interaction.
A33C-1409
Assessing U.S Air Quality Using CALIPSO and MODIS Data via Giovanni
The NASA Goddard online system Giovanni (http://giovanni.gsfc.nasa.gov) provides the scientific community with web based visualization, exploration, and analysis tools relevant to air quality. Relevant data products include MODIS Aerosol Optical Depth (AOD), CALIOP aerosol information, and PM2.5 and ozone surface monitor data. Giovanni services include maps, time series, Hovmoller plots, statistical analysis of one or more data sets for a selected region, and image animations of satellite data. For A-Train sensors, Giovanni is capable of providing vertical profile information for various atmospheric components measured along the A-Train orbit tracks. Additionally, the capability to generate AOD/PM2.5 correlation maps, a research tool for understanding the utility of satellite data for monitoring U.S pollution at various temporal and spatial scales, has been added to the Giovanni system. We present several high pollution events in U.S based on these Giovanni analysis and visualization tools. On August 1-5, 2007 a combination of local pollution sources, long range transport of smoke from Canada and the U.S northwest, and hot and humid conditions lead to a high PM2.5 event over the eastern half of the continental U.S. CALIOP profile data from Giovanni are used here to analyze the vertical transport of the pollution plumes and to better understand the satellite observations and the relative contribution of the various pollution sources to surface PM2.5 concentrations. In the spring of 2007, large wildfires occurred in Georgia and Florida. During the active burning period, Atlanta experienced seven PM2.5 National Ambient Air Quality Standard (NAAQS) exceedances, most occurring during May. Correctly predicting air quality during a wildfire can be difficult, as shown by the missed Air Quality Index (AQI) forecasts for those exceedance days. We use ground- based and multi-satellite data to characterize the impact of these fires on air quality in the Atlanta metropolitan area. The AOD/PM2.5 correlations in conjunction with data on optical properties of urban aerosols and meteorological conditions are examined to determine satellite value-added information for improving air quality modeling in urban areas.
A33C-1410
Validation of OMI NO2 Data to Enhance EPA Ground Network Data: An RPC Experiment
We present an RPC validation study to determine the potential use of OMI tropospheric NO2 column data to enhance spatial surface predictions of NO2 as an augmentation to the continuous NO2 ground network data collected by the State and Local Air Monitoring Stations (SLAMS) and National Air Monitoring Stations (NAMS) for the continental United States. Using one year of OMI and SLAMS/NAMS ground based data from the EPA's Air Quality System (AQS), NO2 values are compared using a variety of statistical techniques including a time series analysis at each EPA ground station in the continental United States, a site-by- site correlation analysis, site-by-site comparison of mean and standard deviation values, and regional (defined by the ten EPA regions) spatial statistics. In addition, a multivariate statistical prediction model with significance testing is developed to determine within a 95% confidence level the impact of concentration, latitude, region, season, environment (urban vs. rural), and pixel size on the correlation of OMI to EPA NO2 data. The robustness of the statistical model is evaluated using statistical methods. Results of this experiment quantify the ability to use OMI-derived NO2 observations to provide predicted surface concentrations to augment the coverage of the existing NO2 ground networks in regions of sparse or non-existent ground monitors. This predictive capability could facilitate a more capable and integrated observing network for NO2 and lead to more informed air quality management decisions at the local, state, and national level.
A33C-1411
NO2 emissions from Western U.S. power plants observed from space
The high spatial resolution and daily coverage of OMI instrument on NASA's EOS Aura platform enables the monitoring of NO2 emissions from individual power plants. Power plants in the western United States provide ideal test cases for comparing emission inventory development methods. These plants are generally isolated from large metropolitan areas, providing relatively distinct signals which can be used to compare bottom-up emission inventory methods with top-down satellite inventory methods. Model NO2 columns simulations using the Weather Research and Forecasting-Chemistry model (WRF-Chem) for the western US domain during the summer of 2005 will be compared with OMI satellite observations.
A33C-1412
MODIS-derived aerosol height for air quality application
Aerosol height plays a critical role in air quality application when using satellite measurements. Up to date, no systematic methods are available to provide aerosol vertical profiles except lidar technology. However the current satellite-based lidar measurements are limited to a narrow line when satellite overpasses. It would need an ensemble of lidar measurements collected from a period of time or from multi-platforms to cover a region such as the United States. With one snapshot, the MODIS-estimated aerosol (top) layer height (hereinafter aerosol height) can provide the 1st order approximation of the vertical extent of aerosol loading derived from the visible spectrum, giving a virtual 3-D view of pollution transported from source to downwind regions. Aerosol height index is developed to show a relative measure between near-surface (aerosol index=0) and elevated aerosol layers (aerosol height index = 2). Aerosol height is estimated to intercompare with ground-based, air- and space-borne lidar measurements. In addition to INTEX-A field campaign period (July 1 – August 15, 2004), a suite of pollution events from 2000 to 2007 will be illustrated in detail along with meteorological fields and trajectory analyses. The immediate applications, in addition to air quality monitoring, include smoke injected height of forest fires (for modeling purpurse) and the conversion of aerosol optical depth to PM2.5 mass concentration.
A33C-1413
Reanalysis and Forecasts of Global Reactive Gases in the GEMS Project
The European GEMS project (Global Environmental Monitoring using Satellite and in-situ data) is setting up a comprehensive modeling system to monitor and predict concentrations of greenhouse gases, reactive gases and aerosols on the global and regional scale. The models are linked to ECMWF's integrated forecast system and include state-of-the-art 4D variational data assimilation of data from multiple satellite instruments. In the GEMS sub project on global reactive gases a focus is placed on monitoring tropospheric and stratospheric ozone and its precursor species (CO, NOx, CH2O) and to establish a system for monitoring the surface UV radiation. Three different chemistry transport models have been coupled to the ECMWF model exchanging trace gas fields and weather variables in one direction and chemical formation and loss rates in the other. The results from this coupled set-up are evaluated using independent data from ground-based networks, aircraft observations (e.g. MOZAIC) and independent satellite retrievals. Tools are being developed to automate the evaluation procedure in order to employ the model in an operational setting. At present, a first reanalysis simulation has been performed for the year 2003 and the coupled model has been tested in near-realtime mode. Two case studies were defined to analyze model performance during the northern hemisphere winter season (with a focus on Arctic ozone depletion) and during the European heat wave in early August 2003. The GEMS model results for these periods are compared to CTM simulations without data assimilation and specific attention is given to model transport characteristics. We will present the strategy and technical design of the GEMS-GRG modeling system, report on various results obtained and lay out the future development path towards a fully operational global atmospheric service. http://www.ecmwf.int/research/EU_projects/GEMS/
A33C-1414
Quantifying the lightning Nox emissions over the US using TES, NLDN, IONS data and the GEOS-Chem model
The Tropospheric Emission Spectrometer (TES) performed extensive observations of the North American and North Atlantic regions during summer 2006. In this study, we use the TES dataset in conjunction with the lightning flashes observed by the National Lightning Detection Network (NLDN) and the Long-Range Lightning Detection Network (LRLDN) to investigate the lightning influence on ozone over the US during July-August 2006. First, TES ozone profiles are compared to the ozonesonde measurements from the IONS (INTEX Ozonesonde Network Study) 2006 campaign to provide validation specific to the North American summer conditions. Then, the lightning influence on the air parcels sampled by TES is investigated by computing forward trajectories initialized at the times and locations of each cloud-to-ground flash observed by the lightning detection networks. Several cases are identified where distinct enhanced ozone layers observed by TES could be related back to lightning events. For these cases, we study the differences between the ozone observed by TES and simulated by GEOS-Chem to infer deficiencies in the lightning NOx parameterization in the model. A different parameterization using recently updated estimate of the NO production by flash is tested in the GEOS-Chem model and resulting predictions compared to the TES data.
A33C-1415
What You Need to Know About the OMI NO2 Data Product for Air Quality Studies
The standard nitrogen dioxide (NO2) data product, produced from measurements by the Ozone Monitoring Instrument (OMI), are publicly available online from the NASA GES-DISC facility. Important data fields include total and tropospheric column densities, as well as collocated data for cloud fraction and cloud top height, surface albedo and snow/ice coverage, at the resolution of the OMI instrument (12 km × 26 km, at nadir). The retrieved NO2 data have been validated, principally under clear-sky conditions. The first public-release version has been available since September 2006. An improved version of the data product, which includes a number of new data fields, and improved estimates of the retrieval uncertainties will be released by the end of 2007. This talk will describe the standard NO2 data product, including details that are essential for the use of the data for air quality studies. We will also describe the principal improvements with the new version of the data product.
A33C-1416
Robust Remote Sensing of Smog Ozone and Its Production
Boundary layer smog ozone and an important tracer of its production, formaldehyde, are indeed fully visible from space at ca. 3.57 microns using an conceptually simple, robust, inexpensive optical train. This is Tropospheric Infrared Mapping Spectrometry, TIMS. Lockheed Martin has demonstrated echelle technology and a low-noise IR detector in application to carbon monoxide, methane, and water using a grating mapping spectrometer in the lab and in the field. A key idea is focus on narrow, very informative spectral regions and a scanning technology; in low Earth orbit, the only moving part is calibration, or in GEO, a standard scanner. A change of echelle-grating order allows a focus on the 3.57 micron region, allowing determination of total ozone column, formaldehyde column with lower-troposphere vertical information, methane, and nitrous oxide (a useful atmospheric-column measurement). A variant of the design operating near 400 nm would provide extremely compact NO2 measurements, thus allowing compact (8 cm diameter) UV devices to be added as useful companions. Robust, inexpensive, rapidly deployable ozone monitoring is thus proposed going far beyond the expectations of the recent Earth Science Decadal Survey of remote sensing possibilities and needs. Our current research emphasizes the published utility of NO2 and HCHO sensing in defining ozone production and its complex emissions sensitivities. The form of the technology implies that variety of options exist, from a rapid-launch, inexpensive 3.57 micron O3-HCHO device to a very compact full-suite complement including more CO, CH4 and NO2 information suitable for geostationary orbit. We also mention that careful statistics using full-column measurements and atmospheric thermal structure information from sounders like AIRS or IASI allow a focus on lower tropospheric ozone with little need for a separate stratospheric-ozone device (SBUV, MLS, HIRDLS). Tropospheric chemistry missions can considerably cut in cost and development time; this is important given the EPA's recent emphasis on the human and economic toll of smog ozone, one justifying stricter standards and a broader regional and international focus. http://geo.arc.nasa.gov/sgg/chatfield/index.html
A33C-1417
Using dynamic aerosol optical properties from a chemical transport model (CTM) to retrieve aerosol optical depths from MODIS reflectances over land
Quantitative evaluation of modeled aerosol fields from global CTMs with aerosol optical depth (AOD) products retrieved from satellite backscattered reflectances can be compromised by inconsistent assumptions of aerosol optical properties and errors in isolating the atmospheric reflectance signal from the surface reflectance noise. We have developed a method for estimating local (1x1.25 degree) 0.47 μm / 2.13 μm and 0.65 μm / 2.13 μm surface reflectance ratios from MODIS top of the atmosphere (TOA) reflectances under conditions where we expect minimal aerosol reflectance. Using these surface reflectance estimates and dynamic aerosol optical properties from the global CTM GEOS-Chem, we model TOA reflectances at 0.47 μm and 0.65 μm for each MODIS scene in the sun / satellite geometry of the instrument using a radiative transfer model. The modeled reflectances are then fit to the MODIS reflectances by iteratively scaling modeled AODs, resulting in a best estimate of AODs for that scene. The MODIS derived AODs are compared with collocated AERONET AODs over the continental US during the summer of 2004. The AODs retrieved using this method show improved comparison with collocated AERONET AODs ( higher correlations, lower RMSE error and lower bias) than the collection 4 or collection 5 MODIS AOD products, particularly at stations located in the Western and Central US. In addition, the joint comparison of collocated AERONET AODs and MODIS reflectances with modeled AODs and reflectances provides insight on the optical properties (aerosol mixing states and hydroscopicity) of modeled aerosols.
A33C-1418
Using satellite remote-sensing data for improving the description of air quality model
Accurate representations of photolysis rates in the photochemical modeling are of utmost importance. In the Community Multiscale Air Quality Modeling System (CMAQ), the method used for photolysis rate calculations depend on the correct estimation of spatially and temporally resolved actinic flux. The current actinic flux in CMAQ is calculated by parameterized variables related to surface albedo, total column ozone, aerosol, clouds, etc., which affect the attenuation of near ultraviolet and visible light. Remotely sensed satellite data provide synoptic and geospatial information with high spatial and temporal resolution, many of which are instrumental for improving the calculation of actinic flux in air quality models. In this study, we compile satellite derived quantities, including the Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF)/Albedo product, the real-time total column ozone data from Total Ozone Mapping Spectrometer (TOMS), vertical ozone profiles retrieved from the recent version of Tropospheric Emission Spectrometer (TES), and TOMS aerosol optical depth data. These values are compared with the corresponding default parameters used in CMAQ for the central California region and the differences are documented. Sensitivity analysis is employed to further quantify the effects of changes in parameters of albedo, column ozone, and aerosol optical depths on photolysis rates and photochemical product concentrations.
A33C-1419
Increasing MODIS aerosol retrievals with image inpainting for 3D-AQS
The MODIS retrieval of aerosol optical depth (AOD) is an essential component of the 3D-AQS (3-Dimensional Air Quality System) collaborative project. In 3D-AQS, satellite, ground and lidar observations of aerosol are collected and displayed in real-time for state and local air quality applications. Although AOD is effective at displaying major aerosol events over the United States, large data gaps due to cloudiness, sun glint and high albedo can impede the interpretability of the AOD imagery. This research explores the application of "inpainting" techniques to fill in data gaps with interpolated values. Unlike conventional interpolation techniques, inpainting preserves edge boundaries in all directions, which minimizes the appearance of interpolation artifacts. Results will show the upper limits of the data gap size that can be effectively restored with inpainting, as well as the relative accuracy of inpainted values.
A33C-1420
Spatio-Temporal Associations of MISR and GOES AOD with Ground-Level PM2.5 Concentrations in Eastern US
As a geostationary satellite, GOES can provide half-hourly AOD measurements during daytime, making available much more dense observations than MISR which is aboard NASA's polar-orbiting satellite. However, limited by instrument design, GOES AOD data have significantly higher uncertainty as compared to MISR observations. We studied the association between aerosol optical depth (AOD) observations from GOES and MISR and daily concentrations of ground-level fine particulate matter (PM2.5) in the eastern United States. Our objective is to integrate GOES and MISR aerosol data into a Bayesian hierarchical modeling system in order to provide spatially and temporally resolved PM2.5 exposure estimates for an on-going large scale health effect study. Our preliminary results show that correlations between AOD and ground-level PM2.5 over time at fixed locations are reasonably high, except in the winter. Correlations over space at fixed times are lower and simple averaging over time actually reduces correlations dramatically. Instead, we propose a calibration approach based on a generalized additive model (GAM) that produces a calibrated AOD value much more highly correlated with PM2.5 and that allows averaging over time to produce stronger correlations. The strength of the association after calibration demonstrates the promise of GOES and MISR AOD for use in supplementing PM2.5 observations and filling in gaps in the sparse monitoring network.
A33C-1421
Global Monitoring of Atmospheric Pollutants from the Aura Satellite
Atmospheric measurements of O3, CO, NO2, SO2, HCHO, Aerosol and other pollutants are routinely made by the OMI, MLS, HIRDLS and TES instruments flown on the EOS Aura satellite since its launch in July 2004. These measurements provide information on the vertical and horizontal distribution of atmospheric pollutants. High concentrations of these pollutants come principally from motor vehicle exhaust, coal and oil combustion, refineries, and biomass burning. These gases play a major role in the formation of unhealthy ground level ozone (or smog) and can trigger serious respiratory problems. The convective transport of these gases, smoke and dust also pollute the upper troposphere and lower stratosphere where the residence time of these pollutants is relatively long and atmospheric winds transport these pollutants to far distances across the oceans and continents. This presentation provides some examples of how Aura data can be used in monitoring air quality by identifying sources of air pollution and understanding the distribution of these pollutants as they get transported extensive distances from their source. In this study we have also used the Aerosol Index data from TOMS, CO data from MOPITT and AIRS, Aerosol data from MODIS, Aerosol layer height information from CALIPSO, and wind information from the NCEP/NCAR reanalysis. This study uses the web based data exploration and analysis tool Giovanni developed at the NASA Goddard Earth Sciences Data Services and Information Center (GES DSIC). Giovanni provides easy access to satellite data, eliminating the need to download large data sets and thus saving the user time. Giovanni capabilities include on- line animations of 2D maps, time-series plots (including statistics), several combinations of 2D cross-section maps (latitude/longitude/height/time), scatter plots, correlation maps, and collocated subsets of the data along CALIPSO tracks. http://giovanni.gsfc.nasa.gov/
A33C-1422
Tropospheric and total NO2 column comparison between ground-based MFDOAS and Aura/OMI retrievals in rural and polluted airsheds.
NO2 total and tropospheric columns were measured by the Washington State University Multi-Function DOAS instrument in clean and polluted conditions at the NASA JPL Table Mountain Facility, CA, rural Pullman, WA and the NASA Goddard Space Flight Center, MD during summer and fall 2007. Vertical NO2 columns were derived from both direct sun and scattered sky observations using air mass factors (AMF) calculated geometrically for direct sun observations and the LIDORT v3.3 radiative transfer model for the sky-scattered radiances. The AIRPACT-3 Pacific Northwest regional air quality forecast system was used to predict a priori NO2 profiles for LIDORT interpretation of the Pullman data. NO2 total and tropospheric columns are compared to Aura/OMI NO2 retrievals as well as in-situ measurements.
A33C-1423
Relations between cloud condensation nuclei and aerosol optical properties: Their sensitivities to size, composition and hygroscopicity observed from aircraft for biomass burning, urban pollution, dust and sea-salt particles over North America
The aerosol distribution and the subset known as cloud condensation nuclei (CCN) is too heterogeneous in space and time to comprehensively measure from ground, ship or aircraft. Global assessment of aerosol effects must depend upon the extended and frequent coverage available from satellite. Satellites, however, do not directly measure the CCN concentration. Satellite radiances are received from particles larger than most CCN, and these are converted to aerosol size distributions based on predetermined aerosol models. We evaluate satellite capabilities to estimate the CCN concentrations given the properties of our observed size distributions and aerosol physico-chemistry. These aerosol properties are derived from aircraft measurements made over North America with NASA DC-8 and NCAR C-130 during INTEX-NA, INTEX-B and MILAGRO campaigns. The relations between the aerosol optical properties and CCN concentrations are examined for the various meteorological, geographical and anthropogenic conditions encountered during the experiments. When volatile organic concentration was high relative to ions, the OPC number tended to be greater than the CCN measured at about 0.2% supersaturation. The aerosol size distribution and composition, which are major factors in determining the CCN concentration, may be constrained with the extinction coefficient, the wavelength dependences of scattering and of absorption, and possibly the single scattering albedo. These revealed relations are being screened and stratified to assess whether the satellite CCN retrieval algorithm can be improved.
A33C-1424
Improved Surface albedo correlation models at high spatial resolution for urban areas using combined MODIS and sky radiometer measurements
Determination of aerosol optical depth from satellite remote sensing measurements is extremely complex due to the large variability of aerosol optical properties. Significant simplification occurs when measurements are taken over water since the ocean reflection signal can be taken as negligible in the NIR.. Unfortunately, over land, most of the signal can be attributed to ground reflectance. In previous work, it was shown that the Collection 4 algorithms severely underestimated urban ground albedo leading to a significant overestimate of aerosol optical depth. This effect was partially compensated in collect 5 who used a dynamic surface albedo model to distinguish surface types and enhance albedo. In this paper, we reassess the accuracy of collection 5 aerosol optical depth in comparison to CIMEL AOD at different spatial resolutions. To obtain these resolutions, the cloud mask must be slightly modified. We find that at 10km resolution, the Collection 5 retrieval has greatly improved retrieval accuracy over collection 4 although a significant overestimate bias is seen. However, when processed at 4km resolution, the vegetation pixels are dramatically reduced in proportion to the urban pixels and the aerosol optical depth from MODIS dramatically overestimates aerosol optical depth. To address this issue, simultaneous matchups from MODIS reflectance at 4km and 1.5km resolution are matched to CIMEL AOD retrievals allowing us to retune the surface albedo model at these higher resolution. Based on large statistical data sets, we find that the angular variation of the albedo is negligible relative to the mean albedo justifying the use of a lambertian model which is then used to develop surface correlation maps for the NYC Metropolitan area. To eliminate the contamination due to local rivers, an additional 2130 mask is used after our cloud clearing has been developed These maps clearly identify the changes of correlation coefficient due to different land surface types. Finally, we demonstrate that using this retuned algorithm results in a significantly improved AOD product at 4km. Finally, simultaneous measurements between neighboring sky radiometers at 2km separation are used to show that the horizontal correlation scale for urban environments are on the order of 4km showing that further improvement of spatial resolution of satellite products is not crucial.