MODIS VALIDATION/CALIBRATION
We are calibrating the MODIS
on-orbit spatial response to an accuracy that will commensurate with calibration
of the MODIS radiometric response. The spatial response will be determined
in terms of the Point Spread Function (PSF)
and Modulation Transfer Function (MTF),
and will be used to develop correction algorithms for MODIS Level 1 data
products. The proposed research program consists of three components:
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Modeling of the MODIS pre-flight spatial response Design specifications
and laboratory measurements are being used to develop a comprehensive,
detailed MODIS PSF model based on its optical,
detector and electronic
components.
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Measurement of the MODIS on-orbit spatial response Simultaneous ASTER
imagery will be used to calibrate the spatial content of the corresponding
portion of MODIS imagery. The MODIS MTF
will be determined from a Fourier analysis of the two imagery sets. ASTER
bands in the VNIR, SWIR, and TIR
will be paired as closely as possible to MODIS bands in each of its four
focal plane subsystems. If available, Landsat-7
imagery may also be used as calibration data. The MODIS on-orbit spatial
response will be compared to the pre-flight model and measurements for
determination of any systematic degradation. Our results will also be compared
to those from experiments planned by NASA for the SpectroRadiometric
Calibration Assembly (SRCA) on MODIS, including scans of the Moon's
limb and of an internal reticle.
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Development and evaluation of spatial response correction for MODIS data
products
-
MODIS spatial response correction functions will be derived and applied
to sample Level 1 radiance data. Experiments will be designed in collaboration
with the MODIS atmosphere, land and ocean science teams to compare the
accuracy of Level 2 geophysical products derived from Level 1 data, with
and without correction for spatial response.
