Imaging Analysis and First Results of the Geostationary Interferometric Microwave Sounder Demonstrator

The Geostationary Interferometric Microwave Sounder (GIMS) is a new concept of atmospheric microwave sounder for China´s future geostationary Earth orbit meteorological satellite (FY-4). It is a microwave interferometric radiometer (MIR) using aperture synthesis and working in rotating time-sharing mode with a circular antenna array. A GIMS proof-of-concept demonstrator operating in the temperature sounding bands of 50-56 GHz has been successfully developed. The instrument uses a circular array with 28 elements (including one in the center of the array). It is capable of imaging a scene with an angular resolution of about 0.08° and a radiometric resolution of less than 1 K with 5-m integration time within a 5° field of view (FOV). Some theoretical aspects of the imaging characteristics of GIMS are discussed, such as the alias-free FOV, angular resolution, radiometric resolution, and imaging algorithm. Some early tests and preliminary imaging experiments of the GIMS demonstrator are also presented.