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Xiaoxiong Xiong - One of the best experts on this subject based on the ideXlab platform.
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Using Dome C for moderate resolution imaging spectroradiometer calibration stability and consistency
2016Co-Authors: Xiaoxiong Xiong, Brian B N. WennybAbstract:Abstract. Currently, there are two nearly identical moderate resolution imaging spectroradiometer (MODIS) instruments operated in space: one on the Terra Spacecraft launched in December 1999 and another on the Aqua Spacecraft launched in May 2002. MODIS has 36 spectral bands with wavelengths covering from visible (VIS) to long-wave infrared (LWIR). Since launch, MODIS observations and data products have significantly enabled studies of changes in the Earth system of land, oceans, and atmosphere. In order to maintain its on-orbit calibration and data product quality, MODIS was built with a comprehensive set of on-board calibrators. MODIS reflective solar bands (RSB) are calibrated on-orbit by a system that consists of a solar diffuser (SD) and a solar diffuser stability monitor (SDSM) on a regular basis. Its thermal emissive bands (TEB) calibration is executed on a scan-by-scan basis using an on-board blackbody (BB). The MODIS Characterization Support Team (MCST) at NASA/GSFC has been responsible for supporting sensor calibration and characterization tasks from pre-launch to post launch. In this paper, we describe current MCST efforts and progress made to examine sensor stability and inter-calibration consistency using observations over Dome Concordia, Antarctica. Results show that this site can provide useful calibration reference for Earth-observing sensors
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characterization of Terra and aqua modis vis nir and swir spectral bands calibration stability
IEEE Transactions on Geoscience and Remote Sensing, 2013Co-Authors: Xiaoxiong Xiong, Amit Angal, David R Doelling, D Morstad, Rajendra BhattAbstract:The Moderate Resolution Imaging Spectroradiometer (MODIS) has successfully operated onboard the Terra Spacecraft for more than 12 years and the Aqua Spacecraft for more than ten years. It has 20 reflective solar bands covering the visible (VIS), near infrared (NIR), and short-wave infrared (SWIR) spectral regions. They are calibrated on orbit using regularly scheduled solar diffuser measurements and lunar observations. In recent years, observations over selected ground targets are also used to monitor detector responses at different angles of incidence. This paper provides a brief description of MODIS on-orbit calibration and characterization methodologies and examines the calibration stability of the VIS, NIR, and SWIR spectral bands over the entire missions of both instruments. Results obtained from four different vicarious approaches (deserts, Dome Concordia, deep convective cloud, and simultaneous nadir overpass) show that Terra MODIS VIS and NIR spectral bands have a wavelength-dependent drift in reflectance with a drop up to 8% in the shortest wavelength region. All four approaches have a relative agreement to within 2.0% with an uncertainty of less than 1.5% for most bands. It is anticipated that the improvements made in the MODIS Collection 6, with additional corrections based on the desert reflectance trending results, will significantly reduce, if not completely remove, some of the trending drifts identified in the Collection-5 data product.
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Terra and aqua moderate resolution imaging spectroradiometer collection 6 level 1b algorithm
Journal of Applied Remote Sensing, 2013Co-Authors: Gary Toller, James Kuyper, Xiaoxiong Xiong, Junqiang Sun, Brian N Wenny, Xu Geng, Amit Angal, Hongda Chen, Sriharsha MadhavanAbstract:The moderate-resolution imaging spectroradiometer (MODIS) was launched on the Terra Spacecraft on Dec.18, 1999 and on Aquaon May 4, 2002. The data acquired by these instruments have contributed to the long-term climate data record for more than a decade and represent a key component of NASA’s Earth observing system. Each MODIS instrument observes nearly the whole Earth each day, enabling the scientific characterization of the land, ocean, and atmosphere. The MODIS Level 1B (L1B) algorithms input uncalibrated geo-located observations and convert instrument response into calibrated reflectance and radiance, which are used to generate science data products. The instrument characterization needed to run the L1B code is currently implemented using time-dependent lookup tables. The MODIS characterization support team, working closely with the MODIS Science Team, has improved the product quality with each data reprocessing. We provide an overview of the new L1B algorithm release, designated collection 6. Recent improvements made as a consequence of on-orbit calibration, on-orbit analyses, and operational considerations are described. Instrument performance and the expected impact of L1B changes on the collection 6 L1B products are discussed.
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status of earth observing system Terra and aqua moderate resolution imaging spectroradiometer level 1b algorithm
Journal of Applied Remote Sensing, 2008Co-Authors: Gary Toller, James Kuyper, Xiaoxiong Xiong, Vincent Chiang, Junqiang Sun, Liqin Tan, William L BarnesAbstract:The first MODerate-resolution Imaging Spectroradiometer (MODIS) was launched on the Terra Spacecraft on December 18, 1999. The second MODIS was launched on the Aqua Spacecraft on May 4, 2002. As an integral part of NASA's Earth Observing System (EOS), these instruments provide daily observations of nearly the whole Earth with the goal of enhancing scientific characterization of land, ocean, atmosphere, climate change, and natural hazards. MODIS uses a scanning mirror, 490 detectors distributed among 36 spectral bands, and on-board calibrators (a solar diffuser, solar diffuser stability monitor, a blackbody, and a spectro-radiometric calibration assembly) to meet these objectives. The MODIS Level 1B (L1B) algorithms, written in C, input uncalibrated, geo-located observations, convert the instrument response into calibrated data, and generate science data sets. This calibration is performed on a pixel-by-pixel basis for each detector. The instrument characterization needed to run the L1B code is implemented using 96 Terra and 99 Aqua Look-up Tables. This paper describes the current L1B algorithm and discusses the changes made as a consequence of on-orbit analyses and operational considerations.
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modis reflective solar bands on orbit lunar calibration
IEEE Transactions on Geoscience and Remote Sensing, 2007Co-Authors: Junqiang Sun, Xiaoxiong Xiong, W Barnes, B GuentherAbstract:The moderate resolution imaging spectroradiometer (MODIS) protoflight model on-board the Terra Spacecraft and the MODIS flight model 1 on-board the Aqua Spacecraft were launched on December 18, 1999 and May 4, 2002, respectively. They view the moon through the space view (SV) port approximately once a month to monitor the long-term radiometric stability of their reflective solar bands (RSBs). The lunar irradiance observed by MODIS depends on the viewing geometry. Algorithms were developed to select lunar views such that these geometric effects are minimized. In each MODIS lunar observation, the moon can be viewed in multiple scans. The lunar irradiance of a MODIS RSB can be derived from the response of all detectors of a spectral band in one scan which fully covers the moon, from that of one detector in multiple scans or from the response of all detectors in multiple scans. Based on lunar observations, a set of coefficients is defined and derived to trend MODIS system response degradation at the angle of incidence (AOI) of its SV port. It is shown that the degradation is both wavelength and mirror side dependent. Since launch, Terra and Aqua MODIS band 8 (412 nm) mirror side one have degraded 36% and 17%, respectively, at the AOI of the SV. A comparison between the lunar coefficients and those derived from the MODIS on-board solar diffuser (SD) calibrations shows that the response change of the MODIS RSB is both AOI and time dependent. Time-dependent response versus scan angle (RVS) lookup tables derived from lunar views, SD calibration, and Earth-view observations have been used to maintain the quality of the L1B data for both the Terra and Aqua MODIS RSB. The corrections provided by the RVS in the Terra and Aqua MODIS data from the 412-nm band are as large as 14% and 6.2%, respectively.
Vincent J. Realmuto - One of the best experts on this subject based on the ideXlab platform.
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misr observations of etna volcanic plumes
Journal of Geophysical Research, 2012Co-Authors: Simona Scollo, Michael J. Garay, Mauro Coltelli, David J Diner, Ralph A Kahn, David L. Nelson, Vincent J. RealmutoAbstract:[1] In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. Volcanic plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of volcanic plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA's Terra Spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the volcanic aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty volcanic plumes produced during the 2000, 2001, 2002–03, 2006 and 2008 Etna eruptions, finding that volcanic aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish volcanic plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of volcanic ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important volcanic plume characteristics that can be used to constrain the eruption source parameters in volcanic ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes.
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three dimensional volcanic aerosol dispersal a comparison between multiangle imaging spectroradiometer misr data and numerical simulations
Journal of Geophysical Research, 2010Co-Authors: Simona Scollo, Mauro Coltelli, Arnau Folch, Vincent J. RealmutoAbstract:[1] The three-dimensional reconstruction of volcanic plumes is a central goal to enhance our understanding on dispersal processes. In this paper we use data from the Multiangle Imaging Spectroradiometer (MISR) on board NASA's Terra Spacecraft combined with a stereo matching retrieval procedure. We show the potential of MISR in capturing important features of volcanic plumes like column height, optical depth, type, and shape of the finest particles of two highly explosive eruptions occurring on Mount Etna in 2001 and 2002. This work tests how tephra dispersal models reconstruct the 3-D shape of volcanic clouds. We compare MISR data with FALL3D, an Eulerian model for the transport and deposition of volcanic ash and aerosols coupled with the Weather Research and Forecasting mesoscale meteorological model. Agreement between simulations and MISR data is good regarding both events, although it could be improved by increasing the accuracy of the meteorological data, a better constraint on volcanological input parameters like the height of the eruptive column and improving our understanding of processes such as aggregation phenomena and volcanic cloud microphysics.
Shunlin Liang - One of the best experts on this subject based on the ideXlab platform.
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distribution function and albedo retrievals: 1. Algorithm performance
2013Co-Authors: Yufang Jin, Crystal B Schaaf, Feng Gao, A H Strahler, Wolfgang Lucht, Shunlin LiangAbstract:was produced at 1-km resolution every 16 days from the observations of the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra Spacecraft. We evaluated the quality of the operational albedo retrievals in two ways: (1) by examining the algorithm performance using the product quality assurance (QA) fields (this paper) and (2) by comparing retrieved albedos with those observed at ground stations and by other satellite instruments (in a companion paper). The internal diagnostics of the retrieval algorithm adequately reflect the goodness of the model fit and the random noise amplification in the retrieved albedo. Global QA statistics show that the RossThick-LiSparse-Reciprocal model fits the atmospherically corrected surface reflectances very well, and the random noise amplification factors for white sky albedo and reflectance are generally less than 1.0. Cloud obscuration is the main reason for the activation of the backup magnitude retrieval algorithm. Over the 60°S to60°Nlatitude band, 50 % of the land pixels acquire more than six clear looks during 14–29 September 2001, and only 5% of these pixels are inverted with the backup algorithm. The latitude dependence and temporal distribution of the QA fields further demonstrate that the retrieval status mainl
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consistency of modis surface bidirectional reflectance distribution function and albedo retrievals 1 algorithm performance
Journal of Geophysical Research, 2003Co-Authors: Yufang Jin, Crystal B Schaaf, Feng Gao, A H Strahler, Wolfgang Lucht, Shunlin LiangAbstract:[1] The first consistent year (November 2000 to November 2001) of global albedo product was produced at 1-km resolution every 16 days from the observations of the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra Spacecraft. We evaluated the quality of the operational albedo retrievals in two ways: (1) by examining the algorithm performance using the product quality assurance (QA) fields (this paper) and (2) by comparing retrieved albedos with those observed at ground stations and by other satellite instruments (in a companion paper). The internal diagnostics of the retrieval algorithm adequately reflect the goodness of the model fit and the random noise amplification in the retrieved albedo. Global QA statistics show that the RossThick-LiSparse-Reciprocal model fits the atmospherically corrected surface reflectances very well, and the random noise amplification factors for white sky albedo and reflectance are generally less than 1.0. Cloud obscuration is the main reason for the activation of the backup magnitude retrieval algorithm. Over the 60°S to 60°N latitude band, 50% of the land pixels acquire more than six clear looks during 14–29 September 2001, and only 5% of these pixels are inverted with the backup algorithm. The latitude dependence and temporal distribution of the QA fields further demonstrate that the retrieval status mainly follows the pattern of angular sampling determined by cloud climatology and the instrument/orbit characteristics. A case study over the west coast of the United States shows that white sky shortwave albedos retrieved from magnitude inversions agree on average with those from full inversions to within 0.033 in reflectance units and have a slightly lower bias ranging from 0.014 to 0.023. We also explored the effect of residual cloud and aerosol contamination in the atmospherically corrected surface reflectance inputs in another case study over southern Africa. The quality assurance procedure of the operational MODIS bidirectional reflectance distribution function and albedo algorithm compensates for some of these residual effects and improves the albedo retrieval results by an order of 0.005 (10%) in the visible for more than 12% of pixels.
David J Diner - One of the best experts on this subject based on the ideXlab platform.
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radiometric stability of the multi angle imaging spectroradiometer misr following 15 years on orbit
Proceedings of SPIE, 2014Co-Authors: Carol J Bruegge, David J Diner, Larry Di Girolamo, Veljko M Jovanovic, E Gray, Guangyu ZhaoAbstract:The Multi-angle Imaging SpectroRadiometer (MISR) has successfully operated on the EOS/ Terra Spacecraft since 1999. It consists of nine cameras pointing from nadir to 70.5° view angle with four spectral channels per camera. Specifications call for a radiometric uncertainty of 3% absolute and 1% relative to the other cameras. To accomplish this, MISR utilizes an on-board calibrator (OBC) to measure camera response changes. Once every two months the two Spectralon panels are deployed to direct solar-light into the cameras. Six photodiode sets measure the illumination level that are compared to MISR raw digital numbers, thus determining the radiometric gain coefficients used in Level 1 data processing. Although panel stability is not required, there has been little detectable change in panel reflectance, attributed to careful preflight handling techniques. The cameras themselves have degraded in radiometric response by 10% since launch, but calibration updates using the detector-based scheme has compensated for these drifts and allowed the radiance products to meet accuracy requirements. Validation using Sahara desert observations show that there has been a drift of ~1% in the reported nadir-view radiance over a decade, common to all spectral bands.
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misr observations of etna volcanic plumes
Journal of Geophysical Research, 2012Co-Authors: Simona Scollo, Michael J. Garay, Mauro Coltelli, David J Diner, Ralph A Kahn, David L. Nelson, Vincent J. RealmutoAbstract:[1] In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. Volcanic plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of volcanic plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA's Terra Spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the volcanic aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty volcanic plumes produced during the 2000, 2001, 2002–03, 2006 and 2008 Etna eruptions, finding that volcanic aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish volcanic plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of volcanic ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important volcanic plume characteristics that can be used to constrain the eruption source parameters in volcanic ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes.
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comparison of coincident multiangle imaging spectroradiometer and moderate resolution imaging spectroradiometer aerosol optical depths over land and ocean scenes containing aerosol robotic network sites
Journal of Geophysical Research, 2005Co-Authors: W A Abdou, David J Diner, Ralph A Kahn, Barbara J Gaitley, John V Martonchik, Lorraine A Remer, Carol J Bruegge, K Crean, Brent N. HolbenAbstract:[1] The Multiangle Imaging Spectroradiometer (MISR) and the Moderate Resolution Imaging Spectroradiometer (MODIS), launched on 18 December 1999 aboard the Terra Spacecraft, are making global observations of top-of-atmosphere (TOA) radiances. Aerosol optical depths and particle properties are independently retrieved from these radiances using methodologies and algorithms that make use of the instruments' corresponding designs. This paper compares instantaneous optical depths retrieved from simultaneous and collocated radiances measured by the two instruments at locations containing sites within the Aerosol Robotic Network (AERONET). A set of 318 MISR and MODIS images, obtained during the months of March, June, and September 2002 at 62 AERONET sites, were used in this study. The results show that over land, MODIS aerosol optical depths at 470 and 660 nm are larger than those retrieved from MISR by about 35% and 10% on average, respectively, when all land surface types are included in the regression. The differences decrease when coastal and desert areas are excluded. For optical depths retrieved over ocean, MISR is on average about 0.1 and 0.05 higher than MODIS in the 470 and 660 nm bands, respectively. Part of this difference is due to radiometric calibration and is reduced to about 0.01 and 0.03 when recently derived band-to-band adjustments in the MISR radiometry are incorporated. Comparisons with AERONET data show similar patterns.
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performance of the misr instrument during its first 20 months in earth orbit
IEEE Transactions on Geoscience and Remote Sensing, 2002Co-Authors: David J Diner, G W Bothwell, J.c. Beckert, J I RodriguezAbstract:The Multi-angle Imaging SpectroRadiometer, one of five science instruments aboard NASA's Terra Spacecraft, was launched into Earth orbit in December 1999. Acquisition of Earth imagery began in February 2000, and the quality of the data is excellent. Overall, MISR has been performing superbly, though the instrument exhibits several idiosyncrasies, some of which were anticipated prior to launch. Details regarding the in-flight performance of the instrument system are presented.
Feng Gao - One of the best experts on this subject based on the ideXlab platform.
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distribution function and albedo retrievals: 1. Algorithm performance
2013Co-Authors: Yufang Jin, Crystal B Schaaf, Feng Gao, A H Strahler, Wolfgang Lucht, Shunlin LiangAbstract:was produced at 1-km resolution every 16 days from the observations of the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA’s Terra Spacecraft. We evaluated the quality of the operational albedo retrievals in two ways: (1) by examining the algorithm performance using the product quality assurance (QA) fields (this paper) and (2) by comparing retrieved albedos with those observed at ground stations and by other satellite instruments (in a companion paper). The internal diagnostics of the retrieval algorithm adequately reflect the goodness of the model fit and the random noise amplification in the retrieved albedo. Global QA statistics show that the RossThick-LiSparse-Reciprocal model fits the atmospherically corrected surface reflectances very well, and the random noise amplification factors for white sky albedo and reflectance are generally less than 1.0. Cloud obscuration is the main reason for the activation of the backup magnitude retrieval algorithm. Over the 60°S to60°Nlatitude band, 50 % of the land pixels acquire more than six clear looks during 14–29 September 2001, and only 5% of these pixels are inverted with the backup algorithm. The latitude dependence and temporal distribution of the QA fields further demonstrate that the retrieval status mainl
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consistency of modis surface bidirectional reflectance distribution function and albedo retrievals 1 algorithm performance
Journal of Geophysical Research, 2003Co-Authors: Yufang Jin, Crystal B Schaaf, Feng Gao, A H Strahler, Wolfgang Lucht, Shunlin LiangAbstract:[1] The first consistent year (November 2000 to November 2001) of global albedo product was produced at 1-km resolution every 16 days from the observations of the Moderate-Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Terra Spacecraft. We evaluated the quality of the operational albedo retrievals in two ways: (1) by examining the algorithm performance using the product quality assurance (QA) fields (this paper) and (2) by comparing retrieved albedos with those observed at ground stations and by other satellite instruments (in a companion paper). The internal diagnostics of the retrieval algorithm adequately reflect the goodness of the model fit and the random noise amplification in the retrieved albedo. Global QA statistics show that the RossThick-LiSparse-Reciprocal model fits the atmospherically corrected surface reflectances very well, and the random noise amplification factors for white sky albedo and reflectance are generally less than 1.0. Cloud obscuration is the main reason for the activation of the backup magnitude retrieval algorithm. Over the 60°S to 60°N latitude band, 50% of the land pixels acquire more than six clear looks during 14–29 September 2001, and only 5% of these pixels are inverted with the backup algorithm. The latitude dependence and temporal distribution of the QA fields further demonstrate that the retrieval status mainly follows the pattern of angular sampling determined by cloud climatology and the instrument/orbit characteristics. A case study over the west coast of the United States shows that white sky shortwave albedos retrieved from magnitude inversions agree on average with those from full inversions to within 0.033 in reflectance units and have a slightly lower bias ranging from 0.014 to 0.023. We also explored the effect of residual cloud and aerosol contamination in the atmospherically corrected surface reflectance inputs in another case study over southern Africa. The quality assurance procedure of the operational MODIS bidirectional reflectance distribution function and albedo algorithm compensates for some of these residual effects and improves the albedo retrieval results by an order of 0.005 (10%) in the visible for more than 12% of pixels.
