Breakthrough achieved in imaging tests of geostationary interferometric millimeter-wave sounder
Significant progress has been made in a serial of field imaging tests on the GIMS (Geostationary Interferometric Millimeter-wave Sounder) demonstrator, in early July, 2011. The first retrieved brightness temperature images taken on some neighborhood buildings around CSSAR registered good image quality. This work is carried out by the Key Laboratory of Microwave Remote Sensing Technology(MiRS Lab/CSSAR/CAS), and supported by the project of “Earth Observation and Navigation Technology” in the National High-tech R&D Program (863 program) as a key research project during the “Eleventh Five Year Plan” (2006~2010).
GIMS is a novel sensor concept proposed by CSSAR for next-generation geostationary meterological satellite, which can provide continuous, large area and all-weather atmospheric observations for short-term weather forecasting or nowcasting. The demonstrator operates at 50~60GHz band with 8 sounding channels and consists of 28 antenna/receiver elements, performing aperture synthesis with a rotating circular thinned array. With the 3-meter diameter array, the demonstrator can synthesize a 6-meter equivalent observation aperture, which makes it capable to realize atmospheric temperature profiling with 50-km spatial resolution from the 36,000km orbit, and get full-coverage imaging on China within 5 minutes.
GIMS demonstrator is the first full-scale prototype which can realized such high spatial resolution. By utilizing rotating interferometric synthetic aperture technology, the required number of antenna/receiver elements has been markedly reduced. The pseudo-polar Fourier transformation has also been introduced to facilitate the image reconstruction. The retrieved millimeter-wave images reveal a lot of features and details of the buildings, and show good consistency with the optical photos taken by a digital camera. These imaging tests successfully demonstrate the instrument concept and also the technology readiness, laying a good foundation for the real implementation of GIMS instrument in space in the future.
