Relative Merits of the 1.6 and 3.75 μm channels of the AVHRR/3 for cloud detection
نویسندگان
چکیده
A study was performed to investigate the potential impacts in the cloud masking capability of the AVHRR on NOAA polar orbiting satellites due to the addition of the of 1.6 μm channel (ch3a) and the removal of the 3.75 μm channel (ch3b) during daylight operation. Both channels are measured by the AVHRR but only one of them are available in the data-stream. Because the AVHRR presents the longest time series of global imager data, this change could potentially impact a critical source of climate data. Specifically, changes in its cloud masking capability may introduce a discontinuity in its derived clear-sky data-records. To study the relative cloud detection capabilities of the AVHRR with ch3a or ch3b, data from MODIS/TERRA was used because it offers both ch3a, ch3b and the other AVHRR channels simultaneously. The MODIS data analysis indicated that ch3b offered more capability in separating cloud from snow. Cloud masking results with ch3a and ch3b performed comparably in separating cloud from aerosol and in detecting cloud over a desert scene.
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