The Experts below are selected from a list of 12474 Experts worldwide ranked by ideXlab platform
Catherine Moroney - One of the best experts on this subject based on the ideXlab platform.
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cloud heights measured by misr from 2000 to 2015
Journal of Geophysical Research, 2017Co-Authors: Roger Davies, Veljko M. Jovanovic, Catherine MoroneyAbstract:Davies and Molloy (2012) reported a decrease in the global effective cloud height over the first 10 years of Multiangle Imaging Spectroradiometer (MISR) measurements on the Terra Satellite. We have reexamined their time series for possible artefacts that might especially affect the initial portion of the record when the heights appeared anomalously high. While variations in sampling were shown to be inconsequential, an artefact due to the change in equator crossing time that affected the first 2 years was discovered, and this has now been corrected. That correction, together with the extension of the time series by five more years, yields no significant overall trend in global heights during the first 15 years of Terra operation. The time series is dominated by large interannual fluctuations associated with La Nina events that mask any overall trend on a global scale. On a regional basis, the cloud heights showed significant interannual variations of much larger amplitude, sometimes with fairly direct cancellation between regions. There were unexplained differences between the two hemispheres in the timing of height anomalies. These differences persisted over a large range of extratropical latitudes, suggestive of teleconnections. Within the tropics, there were very strong changes associated with the Central Pacific and Indonesian Maritime Continent regions that oscillated out of phase with each other, with interannual amplitudes that exceeded 1 km.
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assessment of misr cloud motion vectors cmvs relative to goes and modis atmospheric motion vectors amvs
Journal of Applied Meteorology and Climatology, 2017Co-Authors: Kevin J. Mueller, Janpeter Muller, Veljko M. Jovanovic, Michael J. Garay, Dong L Wu, Ákos Horváth, Larry Di Girolamo, Catherine Moroney, Steve WanzongAbstract:AbstractCloud motion vector (CMV) winds retrieved from the Multiangle Imaging SpectroRadiometer (MISR) instrument on the polar-orbiting Terra Satellite from 2003 to 2008 are compared with collocated atmospheric motion vectors (AMVs) retrieved from Geostationary Operational Environmental Satellite (GOES) imagery over the tropics and midlatitudes and from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery near the poles. MISR imagery from multiple view angles is exploited to jointly retrieve stereoscopic cloud heights and motions, showing advantages over the AMV heights assigned by radiometric means, particularly at low heights (<3 km) that account for over 95% of MISR CMV sampling. MISR–GOES wind differences exhibit a standard deviation ranging with increasing height from 3.3 to 4.5 m s−1 for a high-quality [quality indicator (QI) ≥ 80] subset where height differences are <1.5 km. Much of the observed difference can be attributed to the less accurately retrieved component of CMV motion along the...
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comparison of marine stratocumulus cloud top heights in the southeastern pacific retrieved from Satellites with coincident ship based observations
Journal of Geophysical Research, 2008Co-Authors: Mj Garay, Simon P De Szoeke, Catherine MoroneyAbstract:[1] In order to better understand the general problem of Satellite cloud top height retrievals for low clouds, observations made by NOAA research vessels in the stratocumulus region in the southeastern Pacific during cruises in 2001 and 2003 to 2006 were matched with near-coincident retrievals from the Moderate Resolution Imaging Spectroradiometer (MODIS) and Multiangle Imaging SpectroRadiometer (MISR) instruments on the Terra Satellite, along with a limited set of ISCCP 30-km (DX) retrievals. The ISCCP cloud top heights, determined from the cloud top pressures, were found to be biased high by between 1400 and 2000 m within the limited comparison data set. Like the International Satellite Cloud Climatology Project (ISCCP) results, the MODIS retrievals were biased high by more than 2000 m, while the MISR retrievals had errors on the order of 230 to 420 m, with the wind corrected heights having almost no bias. The extremely large bias in the ISCCP and MODIS retrievals was traced to their reliance on low-resolution observations or models of the atmospheric temperature structure. Cloud top height retrievals based on Satellite cloud top temperatures and a constant atmospheric lapse rate agreed substantially better with the ship-based measurements.
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an assessment of multiangle imaging spectroradiometer misr stereo derived cloud top heights and cloud top winds using ground based radar lidar and microwave radiometers
Journal of Geophysical Research, 2007Co-Authors: Roger Marchand, Thomas P Ackerman, Catherine MoroneyAbstract:[1] In this article stereoscopically derived cloud top heights and cloud winds estimated from the Multiangle Imaging Spectroradiometer (MISR) are assessed. MISR is one of five instruments on board the NASA Terra Satellite. The cloud top height assessment is based on a comparison of more than 4 years of MISR retrievals with that derived from ground-based radar and lidar systems operated by the U.S. Department of Energy Atmospheric Radiation Measurement program. The assessment includes a comparison of the MISR cloud top heights and ground-based data sets as a function of cloud optical depth and a simple cloud classification. Overall, we find that the MISR retrieval is working well with little bias for most cloud types, when the cloud is sufficiently optically thick to be detected. The detection limit is found to be around optical depth 0.3 to 0.5, except over snow and ice surfaces where it is larger. The standard deviation across all clouds is less than about 1000 m for the MISR best winds retrievals at all ARM sites, and the standard deviation for the MISR without winds retrieval varied between about 1000 to 1300 m, depending on the site. The performance for various cloud types is explored.
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cloud motion vectors from misr using sub pixel enhancements
Remote Sensing of Environment, 2007Co-Authors: Roger Davies, Ákos Horváth, Catherine Moroney, Banglin ZhangAbstract:The operational retrieval of height-resolved cloud motion vectors by the Multiangle Imaging SpectroRadiometer on the Terra Satellite has been significantly improved by using sub-pixel approaches to co-registration and disparity assessment, and by imposing stronger quality control based on the agreement between independent forward and aft triplet retrievals. Analysis of the fore-aft differences indicates that CMVs pass the basic operational quality control 67% of the time, with rms differences — in speed of 2.4 m/s, in direction of 17°, and in height assignment of 290 m. The use of enhanced quality control thresholds reduces these rms values to 1.5 m/s, 14° and 165 m, respectively, at the cost of reduced coverage to 45%. Use of the enhanced thresholds also eliminates a tendency for the rms differences to increase with height. Comparison of CMVs from an earlier operational version that had slightly weaker quality control, with 6-hour forecast winds from the Global Modeling and Assimilation Office yielded very low bias values and an rms vector difference that ranged from 5 m/s for low clouds to 10 m/s for high clouds.
Roger Davies - One of the best experts on this subject based on the ideXlab platform.
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cloud heights measured by misr from 2000 to 2015
Journal of Geophysical Research, 2017Co-Authors: Roger Davies, Veljko M. Jovanovic, Catherine MoroneyAbstract:Davies and Molloy (2012) reported a decrease in the global effective cloud height over the first 10 years of Multiangle Imaging Spectroradiometer (MISR) measurements on the Terra Satellite. We have reexamined their time series for possible artefacts that might especially affect the initial portion of the record when the heights appeared anomalously high. While variations in sampling were shown to be inconsequential, an artefact due to the change in equator crossing time that affected the first 2 years was discovered, and this has now been corrected. That correction, together with the extension of the time series by five more years, yields no significant overall trend in global heights during the first 15 years of Terra operation. The time series is dominated by large interannual fluctuations associated with La Nina events that mask any overall trend on a global scale. On a regional basis, the cloud heights showed significant interannual variations of much larger amplitude, sometimes with fairly direct cancellation between regions. There were unexplained differences between the two hemispheres in the timing of height anomalies. These differences persisted over a large range of extratropical latitudes, suggestive of teleconnections. Within the tropics, there were very strong changes associated with the Central Pacific and Indonesian Maritime Continent regions that oscillated out of phase with each other, with interannual amplitudes that exceeded 1 km.
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Intercalibration of CERES, MODIS, and MISR reflected solar radiation and its application to albedo trends
Journal of Geophysical Research: Atmospheres, 2016Co-Authors: Yizhe Zhan, Roger DaviesAbstract:Measurements on the Terra Satellite by the Cloud and the Earth's Radiant Energy System (CERES), the Moderate Resolution Imaging Spectroradiometer (MODIS), and the Multiangle Imaging Spectroradiometer (MISR), between 2001 and 2015 over the polar regions, are analyzed in order to investigate the intercalibration differences between these instruments. Direct comparisons of colocated near-nadir radiances from CERES, MODIS, and MISR show relative agreement within 2.4% decade−1. By comparison with the CERES shortwave broadband, MODIS Collection 6 is getting brighter, by 1.0 ± 0.7% decade−1 in the red band and 1.4 ± 0.7% decade−1 in the near infrared. MISR's red and near-infrared bands, however, show darkening trends of −1.0 ± 0.6% decade−1 and −1.1 ± 0.6% decade−1, respectively. The CERES/MODIS or CERES/MISR visible and near IR radiance ratio is shown to have a significant negative correlation with precipitable water content over the Antarctic Plateau. The intercalibration results successfully correct the differential top-of-atmosphere trends in zonal albedos between CERES and MISR.
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global cloud height fluctuations measured by misr on Terra from 2000 to 2010
Geophysical Research Letters, 2012Co-Authors: Roger Davies, Matthew MolloyAbstract:[1] Self-consistent stereo measurements by the Multiangle Imaging SpectroRadiometer (MISR) on the Terra Satellite yield a decrease in global effective cloud height over the decade from March 2000 to February 2010. The linear trend is −44 ± 22 m/decade and the interannual annual difference is −31 ± 11 m between the first and last years of the decade. The annual mean height is measured with a sampling error of 8 m, which is less than the observed interannual fluctuation in global cloud height for most years. A maximum departure from the 10-year mean, of −80 ± 8 m, is observed towards the end of 2007. These height anomalies correlate well with the changes in the Southern Oscillation Index, with the effective height increasing over Indonesia and decreasing over the Central Pacific during the La Nina phase of the oscillation. After examining the net influence of Central Pacific/Indonesia heights on the global mean anomaly, we conclude that the integrated effects from outside these regions dominate the global mean height anomalies, confirming the existence of significant teleconnections.
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cloud motion vectors from misr using sub pixel enhancements
Remote Sensing of Environment, 2007Co-Authors: Roger Davies, Ákos Horváth, Catherine Moroney, Banglin ZhangAbstract:The operational retrieval of height-resolved cloud motion vectors by the Multiangle Imaging SpectroRadiometer on the Terra Satellite has been significantly improved by using sub-pixel approaches to co-registration and disparity assessment, and by imposing stronger quality control based on the agreement between independent forward and aft triplet retrievals. Analysis of the fore-aft differences indicates that CMVs pass the basic operational quality control 67% of the time, with rms differences — in speed of 2.4 m/s, in direction of 17°, and in height assignment of 290 m. The use of enhanced quality control thresholds reduces these rms values to 1.5 m/s, 14° and 165 m, respectively, at the cost of reduced coverage to 45%. Use of the enhanced thresholds also eliminates a tendency for the rms differences to increase with height. Comparison of CMVs from an earlier operational version that had slightly weaker quality control, with 6-hour forecast winds from the Global Modeling and Assimilation Office yielded very low bias values and an rms vector difference that ranged from 5 m/s for low clouds to 10 m/s for high clouds.
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multi instrument comparison of top of atmosphere reflected solar radiation
Journal of Climate, 2007Co-Authors: Norman G Loeb, Bruce A Wielicki, Takmeng Wong, Konstantin Loukachine, Walter F. Miller, Wenbo Sun, Kory J Priestley, Grant Matthews, Roger DaviesAbstract:Abstract Observations from the Clouds and the Earth’s Radiant Energy System (CERES), Moderate Resolution Imaging Spectroradiometer (MODIS), Multiangle Imaging Spectroradiometer (MISR), and Sea-Viewing Wide-Field-of-View Sensor (SeaWiFS) between 2000 and 2005 are analyzed in order to determine if these data are meeting climate accuracy goals recently established by the climate community. The focus is primarily on top-of-atmosphere (TOA) reflected solar radiances and radiative fluxes. Direct comparisons of nadir radiances from CERES, MODIS, and MISR aboard the Terra Satellite reveal that the measurements from these instruments exhibit a year-to-year relative stability of better than 1%, with no systematic change with time. By comparison, the climate requirement for the stability of visible radiometer measurements is 1% decade−1. When tropical ocean monthly anomalies in shortwave (SW) TOA radiative fluxes from CERES on Terra are compared with anomalies in Photosynthetically Active Radiation (PAR) from SeaWiF...
Michael J. Garay - One of the best experts on this subject based on the ideXlab platform.
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advances in multiangle Satellite remote sensing of speciated airborne particulate matter and association with adverse health effects from misr to maia
Journal of Applied Remote Sensing, 2018Co-Authors: David J Diner, Michael J. Garay, Carol J Bruegge, Larry Di Girolamo, Stacey W Boland, Michael Brauer, Kevin Burke, Russell A Chipman, Sina Hasheminassab, E J HyerAbstract:Inhalation of airborne particulate matter (PM) is associated with a variety of adverse health outcomes. However, the relative toxicity of specific PM types—mixtures of particles of varying sizes, shapes, and chemical compositions—is not well understood. A major impediment has been the sparse distribution of surface sensors, especially those measuring speciated PM. Aerosol remote sensing from Earth orbit offers the opportunity to improve our understanding of the health risks associated with different particle types and sources. The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA’s Terra Satellite has demonstrated the value of near-simultaneous observations of backscattered sunlight from multiple view angles for remote sensing of aerosol abundances and particle properties over land. The Multi-Angle Imager for Aerosols (MAIA) instrument, currently in development, improves on MISR’s sensitivity to airborne particle composition by incorporating polarimetry and expanded spectral range. Spatiotemporal regression relationships generated using collocated surface monitor and chemical transport model data will be used to convert fractional aerosol optical depths retrieved from MAIA observations to near-surface PM10, PM2.5, and speciated PM2.5. Health scientists on the MAIA team will use the resulting exposure estimates over globally distributed target areas to investigate the association of particle species with population health effects.
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development and assessment of a higher spatial resolution 4 4 km misr aerosol optical depth product using aeronet dragon data
Atmospheric Chemistry and Physics, 2017Co-Authors: Michael J. Garay, Olga V. Kalashnikova, Michael A BullAbstract:Abstract. Since early 2000, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra Satellite has been acquiring data that have been used to produce aerosol optical depth (AOD) and particle property retrievals at 17.6 km spatial resolution. Capitalizing on the capabilities provided by multi-angle viewing, the current operational (Version 22) MISR algorithm performs well, with about 75 % of MISR AOD retrievals globally falling within 0.05 or 20 % × AOD of paired validation data from the ground-based Aerosol Robotic Network (AERONET). This paper describes the development and assessment of a prototype version of a higher-spatial-resolution 4.4 km MISR aerosol optical depth product compared against multiple AERONET Distributed Regional Aerosol Gridded Observations Network (DRAGON) deployments around the globe. In comparisons with AERONET-DRAGON AODs, the 4.4 km resolution retrievals show improved correlation (r = 0. 9595), smaller RMSE (0.0768), reduced bias (−0.0208), and a larger fraction within the expected error envelope (80.92 %) relative to the Version 22 MISR retrievals.
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assessment of misr cloud motion vectors cmvs relative to goes and modis atmospheric motion vectors amvs
Journal of Applied Meteorology and Climatology, 2017Co-Authors: Kevin J. Mueller, Janpeter Muller, Veljko M. Jovanovic, Michael J. Garay, Dong L Wu, Ákos Horváth, Larry Di Girolamo, Catherine Moroney, Steve WanzongAbstract:AbstractCloud motion vector (CMV) winds retrieved from the Multiangle Imaging SpectroRadiometer (MISR) instrument on the polar-orbiting Terra Satellite from 2003 to 2008 are compared with collocated atmospheric motion vectors (AMVs) retrieved from Geostationary Operational Environmental Satellite (GOES) imagery over the tropics and midlatitudes and from Moderate Resolution Imaging Spectroradiometer (MODIS) imagery near the poles. MISR imagery from multiple view angles is exploited to jointly retrieve stereoscopic cloud heights and motions, showing advantages over the AMV heights assigned by radiometric means, particularly at low heights (<3 km) that account for over 95% of MISR CMV sampling. MISR–GOES wind differences exhibit a standard deviation ranging with increasing height from 3.3 to 4.5 m s−1 for a high-quality [quality indicator (QI) ≥ 80] subset where height differences are <1.5 km. Much of the observed difference can be attributed to the less accurately retrieved component of CMV motion along the...
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tomographic reconstruction of an aerosol plume using passive multiangle observations from the misr Satellite instrument
Geophysical Research Letters, 2016Co-Authors: Michael J. Garay, Anthony B. Davis, David J DinerAbstract:We present initial results using computed tomography (CT) to reconstruct the three-dimensional structure of an aerosol plume from passive observations made by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra Satellite. MISR views the Earth from nine different angles at four visible and near-infrared wavelengths. Adopting the 672 nm channel, we treat each view as an independent measure of aerosol optical thickness along the line of sight at 1.1 km resolution. A smoke plume over dark water is selected as it provides a more tractable lower boundary condition for the retrieval. A tomographic algorithm is used to reconstruct the horizontal and vertical aerosol extinction field for one along-track slice from the path of all camera rays passing through a regular grid. The results compare well with ground-based lidar observations from a nearby Micropulse Lidar Network (MPLNET) site.
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stereoscopic height and wind retrievals for aerosol plumes with the misr interactive explorer minx
Remote Sensing, 2013Co-Authors: David L Nelson, Michael J. Garay, Ralph A Kahn, Ben A DunstAbstract:The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the Terra Satellite acquires imagery at 275-m resolution at nine angles ranging from 0° (nadir) to 70° off-nadir. This multi-angle capability facilitates the stereoscopic retrieval of heights and motion vectors for clouds and aerosol plumes. MISR's operational stereo product uses this capability to retrieve cloud heights and winds for every Satellite orbit, yielding global coverage every nine days. The MISR INteractive eXplorer (MINX) visualization and analysis tool complements the operational stereo product by providing users the ability to retrieve heights and winds locally for detailed studies of smoke, dust and volcanic ash plumes, as well as clouds, at higher spatial resolution and with greater precision than is possible with the operational product or with other space-based, passive, remote sensing instruments. This ability to investigate plume geometry and dynamics is becoming increasingly important as climate and air quality studies require greater knowledge about the injection of aerosols and the location of clouds within the atmosphere. MINX incorporates features that allow users to customize their stereo retrievals for optimum results under varying aerosol and underlying surface conditions. This paper discusses the stereo retrieval algorithms and retrieval options in MINX, and provides appropriate examples to explain how the program can be used to achieve the best results.
Ralph A Kahn - One of the best experts on this subject based on the ideXlab platform.
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stereoscopic height and wind retrievals for aerosol plumes with the misr interactive explorer minx
Remote Sensing, 2013Co-Authors: David L Nelson, Michael J. Garay, Ralph A Kahn, Ben A DunstAbstract:The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard the Terra Satellite acquires imagery at 275-m resolution at nine angles ranging from 0° (nadir) to 70° off-nadir. This multi-angle capability facilitates the stereoscopic retrieval of heights and motion vectors for clouds and aerosol plumes. MISR's operational stereo product uses this capability to retrieve cloud heights and winds for every Satellite orbit, yielding global coverage every nine days. The MISR INteractive eXplorer (MINX) visualization and analysis tool complements the operational stereo product by providing users the ability to retrieve heights and winds locally for detailed studies of smoke, dust and volcanic ash plumes, as well as clouds, at higher spatial resolution and with greater precision than is possible with the operational product or with other space-based, passive, remote sensing instruments. This ability to investigate plume geometry and dynamics is becoming increasingly important as climate and air quality studies require greater knowledge about the injection of aerosols and the location of clouds within the atmosphere. MINX incorporates features that allow users to customize their stereo retrievals for optimum results under varying aerosol and underlying surface conditions. This paper discusses the stereo retrieval algorithms and retrieval options in MINX, and provides appropriate examples to explain how the program can be used to achieve the best results.
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a geostatistical data fusion technique for merging remote sensing and ground based observations of aerosol optical thickness
Journal of Geophysical Research, 2010Co-Authors: Abhishek Chatterjee, Ralph A Kahn, Anna M Michalak, Susan R Paradise, Amy Braverman, Charles E MillerAbstract:[1] The Multiangle Imaging Spectroradiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Earth Observation System's Terra Satellite have been measuring aerosol optical thickness (AOT) since early 2000. These remote-sensing platforms complement the ground-based Aerosol Robotic Network (AERONET) in better understanding the role of aerosols in climate and atmospheric chemistry. To date, however, there have been only limited attempts to exploit the complementary multiangle (MISR) and multispectral (MODIS) capabilities of these sensors along with the ground-based observations in an integrated analysis. This paper describes a geostatistical data fusion technique that can take advantage of the spatial autocorrelation of the AOT distribution, while making optimal use of all available data sets. Using Level 2.0 AERONET, MISR, and MODIS AOT data for the contiguous United States, we demonstrate that this approach can successfully incorporate information from multiple sensors and provide accurate estimates of AOT with rigorous uncertainty bounds. Cross-validation results show that the resulting AOT product is closer to the ground-based AOT observations than either of the individual Satellite measurements.
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quantifying aerosol direct radiative effect with multiangle imaging spectroradiometer observations top of atmosphere albedo change by aerosols based on land surface types
Journal of Geophysical Research, 2009Co-Authors: Yang Chen, Ralph A Kahn, J T Randerson, David J DinerAbstract:Using internally consistent albedo, aerosol, cloud, and surface data from the Multiangle Imaging Spectroradiometer (MISR) instrument onboard the Terra Satellite, top-of-atmosphere (TOA) spectral albedo change (dα) in the presence of aerosols over land is estimated and its dependence on aerosol and surface properties is analyzed. Linear regressions between spectral TOA albedo and aerosol optical depth (AOD) for different surface types are examined to derive the aerosol-free TOA albedo. MISR surface BiHemispherical Reflectance (BHR) values are used to differentiate surface types. We find relatively high correlations between spectral TOA albedo and AOD for BHR-stratified data in 2° × 2° grid cells. The global mean values of cloud-free dα over land for June–September 2007 are estimated to be 0.018 ± 0.003 (blue), 0.010 ± 0.003 (green), 0.007 ± 0.003 (red), and 0.008 ± 0.006 (near-infrared). Individual regions show large variations from these values. Global patterns of dα are determined mainly by AOD and aerosol radiative efficiency. Large positive values of dα are observed over regions with high aerosol loading and large single-scattering albedo, where the aerosol scattering effect is dominant. The presence of light-absorbing aerosols reduces aerosol radiative efficiency and dα. Surface reflectance influences both aerosol scattering and absorbing effects. Generally, the aerosol radiative efficiency decreases with increasing BHR. We also examined dα-AOD correlations over different vegetation types. We find the smallest dα values are over needleleaf forests and shrublands, whereas the largest values are over cropland and barren regions. The aerosol radiative efficiencies are lowest over needleleaf forests and barren regions and highest over grasslands and croplands.
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analysis of modis misr calibration differences using surface albedo around aeronet sites and cloud reflectance
Remote Sensing of Environment, 2007Co-Authors: Alexei Lyapustin, Alexander Ignatov, A Wu, Brent N. Holben, Ralph A Kahn, Robert E Wolfe, Yujie Wang, Carol J BrueggeAbstract:Abstract MODIS and MISR are two Earth Observing System instruments flown onboard the Terra Satellite. Their synergistic use could greatly benefit the broad user community by ensuring a global view of the Earth with high-quality products. A necessary condition for data fusion is radiometric calibration agreement between the two instruments. Earlier studies showed about 3% absolute radiometric difference between MISR and respective MODIS land bands in the visible and near-IR spectrum, which are also used in aerosol and cloud research. This study compared two surface albedo products derived from MODIS and MISR L1B data using the AERONET-based Surface Reflectance Validation Network (ASRVN). The ASRVN shows a positive MISR–MODIS albedo bias of + (0.01–0.03). Cross-sensor calibration inconsistencies were identified as a primary cause of the albedo biases. To establish an independent MODIS–MISR calibration link, top-of-atmosphere MODIS and MISR reflectances were regressed against each other over liquid water clouds. The empirical regression results have been adjusted for the differences in the respective MISR and MODIS spectral responses using radiative transfer simulations. The MISR–MODIS band gain differences for the top-of-atmosphere reflectance estimated with this technique are + 6.0% in the Blue, + 3.3% in the Green, + 2.7% in the Red, and + 0.8% in the NIR band. Applying the derived values to rescale the MODIS or MISR L1B data is shown to significantly reduce the cross-sensor ASRVN surface albedo biases. An absolute calibration scale for both sensors could be established based on independent ground-based measurements of the surface albedo at selected AERONET sites.
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using angular and spectral shape similarity constraints to improve misr aerosol and surface retrievals over land
Remote Sensing of Environment, 2005Co-Authors: John V Martonchik, Ralph A Kahn, Bernard Pinty, Nadine Gobron, David L NelsonAbstract:Abstract The Multi-angle Imaging SpectroRadiometer (MISR) instrument on the Terra Satellite has demonstrated the capability to retrieve aerosol optical depths, surface bidirectional reflectance factors, and hemispherical reflectances over a wide variety of land surface types. In particular, its multiangular imaging design has enabled the application of algorithms that minimize sensitivity of the aerosol retrievals to the brightness of the underlying surface. The novel aerosol algorithm that was developed prior to launch has had notable quantitative success. Over certain scene types, however, the approach contained obvious spatial artifacts, so a postlaunch refinement to the algorithm was implemented. It constrains the retrieved aerosol models and optical depths such that the implied angular shape of the surface hemispherical–directional reflectance factor (HDRF) is similar among all of the MISR wavelengths. This upgrade has resulted in three tangible benefits: (1) the occurrence of outliers has been dramatically reduced, (2) correlations with AERosol RObotic NETwork (AERONET) aerosol sunphotometer data are quantitatively improved, and (3) the quality of surface products is markedly enhanced. MISR Level 2 aerosol and surface products are archived at the NASA Langley Atmospheric Sciences Data Center. Those having version numbers v0012 and higher incorporate this upgrade in the data processing software.
David J Diner - One of the best experts on this subject based on the ideXlab platform.
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advances in multiangle Satellite remote sensing of speciated airborne particulate matter and association with adverse health effects from misr to maia
Journal of Applied Remote Sensing, 2018Co-Authors: David J Diner, Michael J. Garay, Carol J Bruegge, Larry Di Girolamo, Stacey W Boland, Michael Brauer, Kevin Burke, Russell A Chipman, Sina Hasheminassab, E J HyerAbstract:Inhalation of airborne particulate matter (PM) is associated with a variety of adverse health outcomes. However, the relative toxicity of specific PM types—mixtures of particles of varying sizes, shapes, and chemical compositions—is not well understood. A major impediment has been the sparse distribution of surface sensors, especially those measuring speciated PM. Aerosol remote sensing from Earth orbit offers the opportunity to improve our understanding of the health risks associated with different particle types and sources. The Multi-angle Imaging SpectroRadiometer (MISR) instrument aboard NASA’s Terra Satellite has demonstrated the value of near-simultaneous observations of backscattered sunlight from multiple view angles for remote sensing of aerosol abundances and particle properties over land. The Multi-Angle Imager for Aerosols (MAIA) instrument, currently in development, improves on MISR’s sensitivity to airborne particle composition by incorporating polarimetry and expanded spectral range. Spatiotemporal regression relationships generated using collocated surface monitor and chemical transport model data will be used to convert fractional aerosol optical depths retrieved from MAIA observations to near-surface PM10, PM2.5, and speciated PM2.5. Health scientists on the MAIA team will use the resulting exposure estimates over globally distributed target areas to investigate the association of particle species with population health effects.
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tomographic reconstruction of an aerosol plume using passive multiangle observations from the misr Satellite instrument
Geophysical Research Letters, 2016Co-Authors: Michael J. Garay, Anthony B. Davis, David J DinerAbstract:We present initial results using computed tomography (CT) to reconstruct the three-dimensional structure of an aerosol plume from passive observations made by the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra Satellite. MISR views the Earth from nine different angles at four visible and near-infrared wavelengths. Adopting the 672 nm channel, we treat each view as an independent measure of aerosol optical thickness along the line of sight at 1.1 km resolution. A smoke plume over dark water is selected as it provides a more tractable lower boundary condition for the retrieval. A tomographic algorithm is used to reconstruct the horizontal and vertical aerosol extinction field for one along-track slice from the path of all camera rays passing through a regular grid. The results compare well with ground-based lidar observations from a nearby Micropulse Lidar Network (MPLNET) site.
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quantifying aerosol direct radiative effect with multiangle imaging spectroradiometer observations top of atmosphere albedo change by aerosols based on land surface types
Journal of Geophysical Research, 2009Co-Authors: Yang Chen, Ralph A Kahn, J T Randerson, David J DinerAbstract:Using internally consistent albedo, aerosol, cloud, and surface data from the Multiangle Imaging Spectroradiometer (MISR) instrument onboard the Terra Satellite, top-of-atmosphere (TOA) spectral albedo change (dα) in the presence of aerosols over land is estimated and its dependence on aerosol and surface properties is analyzed. Linear regressions between spectral TOA albedo and aerosol optical depth (AOD) for different surface types are examined to derive the aerosol-free TOA albedo. MISR surface BiHemispherical Reflectance (BHR) values are used to differentiate surface types. We find relatively high correlations between spectral TOA albedo and AOD for BHR-stratified data in 2° × 2° grid cells. The global mean values of cloud-free dα over land for June–September 2007 are estimated to be 0.018 ± 0.003 (blue), 0.010 ± 0.003 (green), 0.007 ± 0.003 (red), and 0.008 ± 0.006 (near-infrared). Individual regions show large variations from these values. Global patterns of dα are determined mainly by AOD and aerosol radiative efficiency. Large positive values of dα are observed over regions with high aerosol loading and large single-scattering albedo, where the aerosol scattering effect is dominant. The presence of light-absorbing aerosols reduces aerosol radiative efficiency and dα. Surface reflectance influences both aerosol scattering and absorbing effects. Generally, the aerosol radiative efficiency decreases with increasing BHR. We also examined dα-AOD correlations over different vegetation types. We find the smallest dα values are over needleleaf forests and shrublands, whereas the largest values are over cropland and barren regions. The aerosol radiative efficiencies are lowest over needleleaf forests and barren regions and highest over grasslands and croplands.
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multi angle imaging spectroradiometer misr time lapse imagery of tsunami waves from the 26 december 2004 sumatra andaman earthquake
Remote Sensing of Environment, 2007Co-Authors: Michael J. Garay, David J DinerAbstract:On 26 December 2004, a few hours after a massive earthquake occurred off the western coast of Sumatra in the Indian Ocean generating a major tsunami, the Multi-angle Imaging SpectroRadiometer (MISR) instrument on NASA's Terra Satellite captured unique, time-lapse evidence of extremely large waves occurring along the eastern coast of India. The MISR imagery provides information on the location and characteristics of tsunami waves in near-shore waters, along with estimates of the wave speed.
