The Multi-angle Imaging SpectroRadiometer instrument is scheduled for launch aboard the first of the Earth Observing System spacecraft, EOS-AM1. MISR will provide global, calibrated, and co-registered imagery at nine discrete viewing angles and four spectral bands. Algorithms developed specifically to capitalize on this measurement strategy will be used to retrieve geophysical products for studies of clouds, aerosols, and surface radiation. This paper provides an overview of the as-built instrument characteristics and the application of MISR to remote sensing of the Earth. I. INTRODUCTION The MISR instrument was delivered by the Jet Propulsion Laboratory to the space- craft contractor, Lockheed Martin Missiles and Space Valley Forge, Pennsylvania, on May 26, 1997. This delivery marked one of many major milestones in preparation for launch, currently scheduled for late-June 1998 from Vandenberg Air Force Base in California. MISR measurements are designed to improve our understanding o...
[Show abstract][Hide abstract] ABSTRACT: The NASA ER-2 aircraft was deployed to southern Africa between 13 August and 25 September 2000 as part of the Southern African Regional Science Initiative (SAFARI) 2000. This aircraft carried a sophisticated array of multispectral scanners, multiangle spectroradiometers, a monostatic lidar, a gas correlation radiometer, upward and downward spectral flux radiometers, and two metric mapping cameras. These observations were obtained over a 3200 × 2800 km region of savanna, woody savanna, open shrubland, and grassland ecosystems throughout southern Africa and were quite often coordinated with overflights by NASA's Terra and Landsat 7 satellites. The primary purpose of this high-altitude observing platform was to obtain independent observations of smoke, clouds, and land surfaces that could be used to check the validity of various remote sensing measurements derived by Earth-orbiting satellites. These include such things as the accuracy of the Moderate Resolution Imaging Spectroradiometer (MODIS) cloud mask for distinguishing clouds and heavy aerosol from land and ocean surfaces and Terra analyses of cloud optical and microphysical properties, aerosol properties, leaf area index, vegetation index, fire occurrence, carbon monoxide, and surface radiation budget. In addition to coordination with Terra and Landsat 7 satellites, numerous flights were conducted over surface AERONET sites, flux towers in South Africa, Botswana, and Zambia, and in situ aircraft from the University of Washington, South Africa, and the United Kingdom. As a result of this experiment, the MODIS cloud mask was shown to distinguish clouds, cloud shadows, and fires over land ecosystems of southern Africa with a high degree of accuracy. In addition, data acquired from the ER-2 show the vertical distribution and stratification of aerosol layers over the subcontinent and make the first observations of a ``blue spike'' spectral emission signature associated with air heated by fire advecting over a cooler land surface.
[Show abstract][Hide abstract] ABSTRACT: Red (672 nm) band reflectance estimates from the NASA multi-angle imaging spectro-radiometer (MISR) on the earth observing system Terra satellite were used to obtain maps of woody plant fractional crown cover, mean canopy height, and biomass for large parts of south-eastern Arizona and southern New Mexico (>200,000 km<sup>2</sup>). MISR red band bidirectional reflectance estimates in nine views mapped to a 250 m grid were used to adjust the simple geometric-optical model (SGM) that is based on the principles of Boolean geometry first exploited in Li-Strahler geometric-optical (GO) models. The soil-understory background signal was decoupled a priori by exploiting relationships with the nadir camera reflectance data and the kernel weights of the LiSparse-RossThin kernel-driven bidirectional reflectance distribution function (BRDF) model. Maps of fractional crown cover, mean canopy height, and biomass were produced via retrievals of the mean crown radius and shape parameters from inversion of the SGM using the Praxis algorithm. The mean absolute error in randomly sampled and filtered estimates of fractional crown cover, mean canopy height, and woody biomass was 0.10, 2.2 meters, and 4.5 tons acre<sup>-1</sup> (10.1 Mg ha<sup>-1</sup>), with RMS errors of 0.12, 3.3 and 6.2 (14.0), and coefficients of determination (R<sup>2</sup>) of 0.78, 0.69, and 0.81, respectively, significant at the 0.01 level (N=576).
[Show abstract][Hide abstract] ABSTRACT: During the dry season, anthropogenic fires in tropical forests and peatlands of equatorial Asia produce regionally expansive smoke clouds that have important effects on atmospheric radiation and air quality. Here we estimated the height of smoke on Borneo and Sumatra and characterized its sensitivity to El Niño and regional drought. We used Multiangle Imaging Spectroradiometer (MISR) satellite data and the MISR Interactive Explorer (MINX) software to estimate the heights of 317 smoke plumes on Borneo and 139 plumes on Sumatra during 2001-2009. In addition, we estimated the altitudes of larger smoke regions (smoke clouds) over Borneo using data from MISR and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) products. Most smoke plumes on Borneo (83%) were observed during El Nio years. Annually averaged plume heights on Borneo were significantly higher during El Niño events. Mean MISR-derived plume heights were 709 ± 14 m on Borneo and 749 ± 24 m on Sumatra during 2001-2009, with 96% of all plumes confined to within 500 m of the atmospheric boundary layer. Smoke clouds on Borneo were observed at altitudes between 1000 and 2000 m as measured by both MISR and CALIPSO. The difference in height between individual plumes and longer-lived regional smoke clouds may be related to deeper planetary boundary layers and higher-intensity fires later in the afternoon or other atmospheric mixing processes that occur on synoptic time scales. Our measurements and analyses suggested that direct injection of smoke into the free troposphere within fire plumes was not an important mechanism for vertical mixing of aerosols in equatorial Asia.
Journal of Geophysical Research Atmospheres 04/2011; 116(D8). DOI:10.1029/2010JD015148 · 3.43 Impact Factor
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