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An Airborne Multi-angle Imaging SpectroRadiometer (AirMISR) instrument has been developed to assist in validation of the Earth Observing System (EOS) MISR experiment.
The Multi-angle Imaging SpectroRadiometer (MISR) is currently under development for NASA's Earth Observing System (EOS). The instrument consists of nine pushbroom cameras, each with four spectral bands in the visible and near-infrared. Detailed are the MISR preflight characteristics, design of the On-Board Calibrator, and the radiance product processing. Detailed specifications and test plans are given.
The Multi-Angle Imaging SpectroRadiometer (MISR) is being developed at JPL for the AM1 spacecraft in the Earth Observing System (EOS) series. This paper reports on the progress of instrument fabrication and testing, and it discusses the strategy to use the instrument for studying tropospheric aerosols.
Multi-angle, multi-spectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multi-angle Imaging SpectroRadiometer (MISR), can distinguish spherical from non-spherical particles over calm ocean for mineral-dust-like particles with the range of sizes and column amounts expected under natural conditions. The ability to make such distinctions is critical if remote sensing of atmospheric aerosol properties is to provide significant new contributions to our understanding of the global-scale, clear-sky solar radiation balance.
The Multi-angle Imaging SpectroRadiometer (MISR) plans to use deployable diffuse reflectance panels to provide periodic radiometric calibrations of its nine cameras while in-flight. Near-Lambertian reflectance characteristics are desirable to facilitate flat-field camera intercomparisons. Also required is panel spatial and spectral uniformity, and stability with time. Spectralon, a commercially available polytetrafluoroethylene (PTFE) compound, has been baselined in the MISR design. To assess the suitability of this material, a series of degradation tests were planned and implemented. These included UV vacuum exposure and proton bombardment tests which simulated the exposure levels to be encountered during the mission life. Proton levels are now considered too low to be of concern, but UV vacuum tests demonstrate sensitivity to material contamination. Material investigations have concluded that hydrocarbons are present in the bulk of the material, and that plastic packaging materials can introduce additional surface-layer contamination. It is found however, that these unwanted elements can be eliminated through vacuum pumping at elevated temperatures. Exposure to a UV source, while in vacuum, is again planned for a set of targets which have been vacuum baked. This will assess the stability of the pure PTFE form.
The in-flight calibration of the EOS Multi-angle Imaging SpectroRadiometer (MISR) will be achieved, in part, by observing deployable Spectralon panels. This material reflects light diffusely, and allows all cameras to view a near constant radiance field. This is particularly true when a panel is illuminated near the surface normal. To meet the challenging MISR calibration requirements, however, very accurate knowledge of the panel reflectance must be known for all utilized angles of illumination, and for all camera and monitoring photodiode view angles. It is believed that model predictions of the panels Bidirectional Reflectance Distribution Function (BRDF) can be used in conjunction with a measurements program to provide the required characterization. This paper describes the results of a model inversion which was conducted using measured Spectralon BRDF data at several illumination angles. Four physical parameters of the material were retrieved, and are available for use with the model to predict reflectance for any arbitrary illumination or view angle. With these data the root mean square difference between the model and the observations is currently of the order of the noise in the data, at about +/- l%. With this success the model will now be used in a variety of future studies, including the development of a measurements test plan, the validation of these data, and the prediction of a new BRDF profile, should the material degrade in space.
Partnered with Goddard Space Flight Center, Sensit Technologies Inc. developed a third-generation Portable Apparatus for Rapid Acquisitions of Bidirectional Observations of Land and Atmosphere, or PARABOLA III for short. Now commercially available, PARABOLA III is designed to measure the reflected signature of a variety of Earth surface types, from rangeland vegetation to ice and snow. It can rapidly acquire data for almost the complete sky and ground-looking hemispheres, with no missing data and sufficient dynamic range to measure direct solar radiance. The instrument was actively used in the Boreal Ecosystem- Atmosphere Study which provided useful information in designing a Multi-angle Imaging SpectroRadiometer, a small satellite being built by the Jet Propulsion Laboratory that will measure sunlight reflected by the Earth into space.
This Algorithm Theoretical Basis (ATB) document describes the algorithms used to generate the parameters of certain ancillary products and datasets used during Level 2 processing of Multi-angle Imaging SpectroRadiometer (MIST) data.
This paper will describe the production of the Ancillary Geographic Product (AGP) in support of the Earth Observing System (EOS) Multi-angle Imaging SpectroRadiometer (MISR) instrument data processing. The AGP is essentially a global database of geographic properties, tailored to the needs of the MISR mission.
Light reflected from Spectralon, the material chosen for on-board radiometric calibration of the Multi-angle Imaging SpectroRadiometer (MISR) is quantified in terms of the fraction of the reflected intensity that has the same polarization as the incident light.
The design of an Earth Remote Sensing Sensor, such as the Multi-angle Imaging SpectroRadiometer (MISR), begins with a set of science requirements and is quickly followed by a set of instrument specifications.
Multiangle, multispectral remote sensing observations, such as those anticipated from the Earth Observing System (EOS) Multi-angle Imaging SpectroRadiometer (MISR), can significantly improve our ability to constrain aerosol properties from space.
An Airborne Multi-angle Imaging SpectroRadiometer (AirMISR) instrument has been developed to assist in validation of the Earth Observing System (EOS) MISR experiment.
Clouds and aerosols are fundamental regulators of Earth’s radiation budget and climate system, influencing both solar and terrestrial radiation through scattering, absorption, and emission processes. Accurate characterization of their physical and radiative properties from space requires a rigorous understanding of particle single-scattering, gaseous absorption, and radiative transfer in the atmosphere, as well as reliable inversion methods. This review synthesizes the physical foundations and algorithmic implementations of satellite-based passive optical remote sensing of clouds and aerosols, spanning the ultraviolet to thermal infrared spectral range. Beginning with electromagnetic scattering theory and state-of-the-art methods for computing single-scattering by nonspherical particles and computationally efficient methods for accounting for atmospheric absorption, we discuss the radiative transfer framework underpinning cloud and aerosol retrievals. The connection between single-scattering and multiple-scattering is rigorously formulated. We then summarize operational and research-grade retrieval techniques, including cloud masking and thermodynamic phase determination, CO₂ slicing for cloud-top pressure, the Nakajima-King shortwave bi-spectral, and infrared split-window approaches for cloud optical thickness and effective particle size, inversion algorithms for determining aerosol properties from multi-spectral and/or multi-angle radiometric and polarimetric measurements, and active-passive sensing synergy. Examples of the global cloud and aerosol climatologies are illustrated using observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Multi-angle Imaging SpectroRadiometer (MISR). Furthermore, the unique strengths of active remote sensing techniques based on spaceborne lidar observations are briefly elaborated in the context of studying ice clouds composed of randomly and horizontally oriented ice crystals, which is a significant challenge for conventional passive remote sensing techniques. By connecting physical theory to practical retrievals, this review highlights both the maturity of current methodologies and the remaining challenges in reducing uncertainties in particle morphology, vertical structure, absorption, and aerosol-cloud interactions. Furthermore, the impact of artificial intelligence (AI) on atmospheric remote sensing is briefly addressed.
Spectral aerosol optical depths and surface hemispherical directional reflectance factors and bihemispherical reflectances are retrieved using multi-angle imagery taken by the airborne Advanced Solid-State Array Spectroradiometer.
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Each of the nine cameras which compose the Multi-angle Imaging SpectoRadiometer (MISR) has been regorously tested, characterized, and Calibrated.
This paper describes the results of a model inversion which was conducted using measured Spectralon BRDF data at several illumination angles. We can describe the bidirectional reflectance of the Spectralon and in paticular its slight anisotrophy with a physically-based model. The root mean square difference between the model and the observations is currently of the order of the noise in the data (+/-1%). It is expected that meaningful corrections to account for the anisotrophy of the Spectralon panels will be achieved in the next few years and will improve the calibration of the MISR instrument.