A preview of AMSR: Airborne C-band Microwave Radiometer (ACMR) observations from SGP99

Although the L-band (1.4 GHz) is generally considered ideal for passive microwave sensing of soil moisture, near-future satellite instruments such as the Advanced Microwave Scanning Radiometer (AMSR) will provide C-band (~7 GHz) observations, not L-band observations. Prior to 1999, adequate field testing of soil moisture retrieval algorithms using C-band observations had been hampered due to a lack of suitable data, particularly aircraft datasets over regions at satellite pixel scales (>1000 km2). The Southern Great Plains 99 (SGP99) Experiment was designed to fill this gap with aircraft flights featuring five low-frequency passive microwave instruments. The C-band observations described in this paper were collected using one of the two new C-band instruments deployed during SGP99: the Airborne C-band Microwave Radiometer (ACMR)