ABSTRACT--TheMODIS radiometric calibration product (Level 1B) is described for the thermal emissive and the reflective solar bands. Specific sensor design characteristics are identified to assist in understanding how the calibration algorithm software product is designed. The reflected solar band software products of radiance and reflectance factor both are described. The product file format is summarized and the MCST Homepage location for the current file format is provided.
A general modelling formalism is used to extend near-field point spread function (PSF) measurements over a wide-field off-axis angular range, covering a dynamic range of 5 to 6 orders of magnitude, using bidirectional reflectance distribution function (BRDF) measurements of the scan mirror and other key optical elements. Line spread function (LSF) model results were compared with measured near-field LSF measurements for the Moderate Resolution Imaging Spectroradiometer (MODIS) of the Earth Observing System (EOS), demonstrating excellent agreement between model and measurements. When realistic effects of sensor scattered light are taken into account, significant radiometric bias errors are produced near high-contrast structured scenes (e.g. bright clouds over dark oceans and land; broken snow and ice scenes). Image restoration using an asymptotically exact PSF is shown to produce results significantly different from those produced by traditional near-field 5 5, 7 7, , PSF kernel matrix inversion techniques. The results reported have implications for future remote-sensor specifications and testing, in-flight and surface-based calibration comparisons, and the assessment of radiometric bias errors in the presence of moderate-to high-contrast Earth scenes.
A grazing incidence spectrograph launched in a Black Brant rocket August 30, 1973, at White Sands Missile Range obtained high spectral resolution data of the solar radiation between 200 and 700 A. Absolute intensities and profiles of the brighter lines in this spectral region were measured. Results for the He I 584-A and He II 304-A lines are presented. For the He I 584-A line the full width at half intensity is 0.08 A, and the intensity for the solar disk is 1.3 X 109 photons cm -•' s -•. For the 304-A He II line these values are 0.12 A and 6.3 X 109 photons cm -2 s -•, respectively.
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