Multi-angle Imaging SpectroRadiometer Instrument Description and Experiment Overview
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...
Available from: Charles Gatebe
- "Moderate Resolution Imaging Spectroradiometer- MODIS (Xiong et al., 2011), now retired Polarization and Directionality of the Earth's Reflectances-POLDER (Deschamps et al., 1994), Clouds and Earth's Radiant Energy System-CERES (Wielicki et al., 1996), multiple forward and aft sensors (e.g. Multiangle Imaging SpectroRadiometer-MISR (Diner et al., 1998), Along Track Scanning Radiometer-ATSR (Godsalve, 1995), Advanced Spaceborne Thermal Emission and Reflection Radiometer-ASTER (Abrams, 2000), or autonomous maneuverability to point at pre-programmed ground targets (e.g. Compact High Resolution Imaging Spectrometer -CHRIS (Barducci et al., 2005). "
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ABSTRACT: The bidirectional reflectance distribution function (BRDF) gives the reflectance of a target as a function of illumination geometry and viewing geometry, hence carries information about the anisotropy of the surface. BRDF is needed in remote sensing for the correction of view and illumination angle effects (for example in image standardization and mosaicing), for deriving albedo, for land cover classification, for cloud detection, for atmospheric correction, and other applications. However, current spaceborne instruments provide sparse angular sampling of BRDF and airborne instruments are limited in the spatial and temporal coverage. To fill the gaps in angular coverage within spatial, spectral and temporal requirements, we propose a new measurement technique: Use of small satellites in formation flight, each satellite with a VNIR (visible and near infrared) imaging spectrometer, to make multi-spectral, near-simultaneous measurements of every ground spot in the swath at multiple angles. This paper describes an observing system simulation experiment (OSSE) to evaluate the proposed concept and select the optimal formation architecture that minimizes BRDF uncertainties. The variables of the OSSE are identified; number of satellites, measurement spread in the view zenith and relative azimuth with respect to solar plane, solar zenith angle, BRDF models and wavelength of reflection. Analyzing the sensitivity of BRDF estimation errors to the variables allow simplification of the OSSE, to enable its use to rapidly evaluate formation architectures. A 6-satellite formation is shown to produce lower BRDF estimation errors, purely in terms of angular sampling as evaluated by the OSSE, than a single spacecraft with 9 forward-aft sensors. We demonstrate the ability to use OSSEs to design small satellite formations as complements to flagship mission data. The formations can fill angular sampling gaps and enable better BRDF products than currently possible.
International Journal of Applied Earth Observation and Geoinformation 09/2015; 43:102. DOI:10.1016/j.jag.2015.04.022 · 3.47 Impact Factor
Available from: Jochem Verrelst
- "In the global data acquisition mode, eight oblique cameras observe the Earth's surface at a resolution of 1100 m in blue, green, and near-infrared (NIR) bands and at a resolution of 275 m in the red domain. In addition, all four bands of the nadir-observing camera have a spatial resolution of 275 m (Diner et al., 1998). Pinty et al. (2002) reported that the availability of sufficient brightness contrast between overstory and background in conjunction with a relatively high sun position (sun zenith ,60u) is instrumental to correctly exploit the Minnaert-k parameter in the interpretation of the anisotropy of the reflectance. "
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ABSTRACT: We report on a detailed analysis of hyperspectral and multidirectional remote sensing data acquired using the Compact High Resolution Imaging Spectrometer (CHRIS) mounted onboard the Project for On-Board Autonomy (PROBA) spacecraft. This instrument is capable of sampling reflected radiation over the visible and near-infrared (NIR) region of the solar spectrum at a spatial resolution (approx. 17 m) intermediary between sensors traditionally used in land applications (such as Landsat and Satellite Pour l’Observation de la Terre (SPOT), 30 m–50 m) and the latest instruments delivering a nominal resolution of 1 m or less. The spectral anisotropic signature of an Alpine coniferous forest during winter in relation to canopy cover was investigated using the Minnaert-k parameter obtained by inverting the Rahman–Pinty–Verstraete (RPV) model against CHRIS data. Although earlier studies have demonstrated that Minnaert- k can be used to characterize surface heterogeneity at subpixel scale, its spectral dependency has not yet been fully assessed in an imaging spectrometry context. Minnaert-k parameter retrievals across CHRIS bands revealed that a switch from bell-shaped to bowl-shaped anisotropic reflectance patterns occurs when comparing visible to NIR responses. Specifically, the degree of canopy cover and background brightness determine where in the spectral domain this switch in reflectance anisotropy occurs. For a bright snow cover background Minnaert-k values correlated best with canopy cover at the end of the red edge (e.g., around 735 nm). In this spectral region, pixels with medium canopy cover (40%–70%) typically produced bell-shaped anisotropy patterns, while pixels with sparse (,30%) or dense (.70%) canopy covers typically produced bowl-shaped reflectance anisotropy patterns.
Canadian Journal of Remote Sensing 12/2010; 36(6):631-644. DOI:10.5589/m11-012 · 1.73 Impact Factor
Available from: Michael D. King
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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.
01/2003; 108(13). DOI:10.1029/2002JD003207
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