|PENG, J. - Goddard Space Flight Center|
|MISRA, S. - Jet Propulsion Laboratory|
|PIEPMEIER, J. - Goddard Space Flight Center|
|DINNAT, E. - Goddard Space Flight Center|
|HUDSON, D. - Goddard Space Flight Center|
|LEVINE, D. - Goddard Space Flight Center|
|DE AMICI, G. - Goddard Space Flight Center|
|MOHAMMAD, P. - Goddard Space Flight Center|
|BINDLISH, R. - Goddard Space Flight Center|
|YUEH, S. - Jet Propulsion Laboratory|
|MEISSNER, T. - Santa Rosa Junior College|
Submitted to: IEEE Transactions on Geoscience and Remote Sensing
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2017
Publication Date: 9/1/2017
Citation: Peng, J., Misra, S., Piepmeier, J., Dinnat, E., Hudson, D., Levine, D., De Amici, G., Mohammad, P., Bindlish, R., Yueh, S., Meissner, T., Jackson, T.J. 2017. Soil Moisture Active/Passive (SMAP) L-band microwave radiometer post-launch calibration. IEEE Transactions on Geoscience and Remote Sensing. 55:1897-1914.
Interpretive Summary: The calibration methods of Soil Moisture Active Passive (SMAP) satellite radiometer brightness temperatures were assessed to determine if they provide data of sufficient accuracy and quality. Calibration methods include Cold Sky and vicarious ocean calibration with effective antenna pattern considered. Calibration quality including stability was assessed using global ocean and Cold Sky targets, and intercompared with the brightness temperature of the Soil Moisture Ocean Salinity (SMOS) satellite. Assessment results show that radiometric uncertainty in the radiometer data product meets the SMAP project requirements (uncertainty < 1.3 K and calibration drift < 0.4 K/months), and geo-location uncertainty is within 2.7 km which meets its requirement with ample margin. The assessment results suggest that further refinement would be beneficial. The verification of the instrument performance provides the developers of geophysical products with greater confidence in applying the brightness temperature and the end users in hydrologic and agricultural management with more accurate and reliable soil moisture information.
Technical Abstract: The SMAP microwave radiometer is a fully-polarimetric L-band radiometer flown on the SMAP satellite in a 6 AM / 6 PM sun-synchronous orbit at 685-km altitude. Since April 2015, the radiometer has been under calibration and validation to assess the quality of the radiometer L1B data product. Calibration methods including the SMAP L1B TA2TB (from Antenna Temperature (TA) to the Earth’s surface Brightness Temperature (TB)) algorithm and TA forward models are outlined, and validation approaches for calibration stability/quality are described in this paper including future work. Results show that the current radiometer L1B data product (version 3) satisfies its requirements (uncertainty < 1.3 K and calibration drift < 0.4 K/months, and geolocation uncertainty < 4 km) although there are biases in TA over Cold Sky (CS) and in TB comparing to the Soil Moisture and Ocean Salinity (SMOS) TB v620 data products.