Airborne microwave radiometer for AMSR and AMSR-E project

ABSTRACT The Airborne Microwave Radiometer (AMR) is a multifrequency, passive microwave radiometer to be installed on anaircraft. From 1996, the AMR has been used in two spaceborne instrument projects: the Advanced Microwave ScanningRadiometer (AMSR) on the Advanced Earth Observing Satellite-II (ADEOS -II) and the AMSR-E on the EOS Aqua satel lite.The major objectives of AMR are to develop retrieval algorithms and to calibrate and validate AMSR and AMSR-E. Werecently modified the instrument to improve its stability and usability. The results of a set of test flights show an improvedin-flight and interflight stability. We will conduct several AMR underflights to confirm AMSR and AMSR-E on-orbitcalibration.Keywords: Microwave radiometer, aircraft, calibration and validation 1. INTRODUCTION The National Space Development Agency of Japan (NASDA) is developing two space-borne microwave radiometers: theAdvanced Microwave Scanning Radiometer (AMSR) on the Advanced Earth Observing Satellite-II (ADEOS-II) andAMSR-E on EOS Aqua platform. These are new generation passive microwave radiometers with high spa tial resolution andnew frequency channels for global observation of various geophysical parameters related to water and energy circulation.The Airborne Microwave Radiometer (AMR) was designed for developing prelaunch retrieval algorithms and forcalibrating and validating of AMSR and AMSR-E after launch. Flight campaigns using the AMR were conducted fordiverse geophysical parameters such as sea surface temperature, sea surface wind direction (anisotropy of microwaveemission due to wind direction), soil moisture content, sea ice concentration, and snow clouds. We recently modified theinstrument to improve its stability and usability. In this paper, we will describe the characteristics and performance of theAMR, then present the results of a set of test flights conducted to confirm the improvements after the modification.