Intercalibration and Validation of Observations From ATMS and SAPHIR Microwave Sounders
Journal article, 2015
This paper evaluates the radiometric accuracy of observations from the Advanced Technology Microwave Sounder (ATMS) onboard Suomi National Polar-orbiting Partnership and Sondeur Atmospherique du Profil d' Humidite Intropicale par Radiometrie (SAPHIR) onboard Megha-Tropiques through intercalibration and validation versus in situ radiosonde and Global Positioning System Radio Occultation (GPS-RO) observations. SAPHIR and ATMS water vapor channels operate at slightly different frequencies. We calculated the bias due to radiometric errors as the difference between the observed and simulated differences between the two instruments. This difference, which is often referred to as double difference, ranges between 0.3 and 0.7 K, which shows good consistency between the instruments. We used a radiative transfer model to simulate the satellite brightness temperatures (Tbs) using radiosonde and GPS-RO profiles and then compared simulated and observed Tbs. The difference between radiosonde and ATMS Tbs for the middle and upper tropospheric temperature sounding channels was less than 0.5 K at most stations, but the difference between radiosonde and ATMS/SAPHIR Tbs for water vapor channels was between 0.5 and 2.0 K. The larger bias for the water vapor channels is mainly due to several errors in radiosonde humidity observations. The mean differences between the ATMS observations and the Tbs simulated using GPS-RO profiles were 0.2, 0.3, 0.4, 0.2, and -0.2 K for channels 10-14, respectively; and the uncertainty increases from 0.02 K for channel 10 to 0.07 K for channel 14.
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1991
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satellite
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& Photographic Technology
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Climate change
cloud ice
Imaging Science
Geochemistry & Geophysics
p63
data record
radiosonde
Joint Polar Satellite System (JPSS)
water vapor
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microwave
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Author
I. Moradi
University of Maryland
National Oceanic and Atmospheric Administration
R. R. Ferraro
National Oceanic and Atmospheric Administration
Patrick Eriksson
Chalmers, Earth and Space Sciences, Global Environmental Measurements and Modelling
F. Z. Weng
National Oceanic and Atmospheric Administration
IEEE Transactions on Geoscience and Remote Sensing
0196-2892 (ISSN) 15580644 (eISSN)
Vol. 53 11 5915-5925 7122324Subject Categories
Climate Research
DOI
10.1109/tgrs.2015.2427165