Non-uniform phase filter for Tiangong-2 Interferometric Imaging Radar Altimeter

Abstract

The interferometric imaging radar altimeter (InIRA) on-board Chinese Tiangong-2 space laboratory is a Ku-band interferometric radar whose major aim is to measure the wide-swath ocean topography. Unlike traditional interferometric synthetic aperture radar (InSAR) aiming at measuring digital elevation model of land surface, Tiangong-2 InIRA adopts small incidence angles and short baseline to get strong and high coherency reflections from ocean surface. The interferometric phase noise is a notable source of errors which limits the accuracy of the ocean height measurements. Compared with traditional InSAR, the height error of Tiangong-2 InIRA shows different distribution pattern due to the absolutely small but relatively large variation incidence angles. This study gives a filtering method for interferometric phase generated with small incidence angles and short baseline. Non-uniform windows are selected according to the relation between the coherence, imaging geometry, and the height variation. Results on Tiangong-2 InIRA data are analysed by comparing the non-uniform filtering method with traditional multi-looking method.

Keywords

• radar interferometry
• radar altimetry
• radar imaging
• topography (Earth)
• digital elevation models
• oceanographic techniques
• remote sensing by radar
• synthetic aperture radar
• nonuniform windows
• Tiangong-2 InIRA data
• nonuniform filtering method
• nonuniform phase filter
• Tiangong-2 interferometric imaging radar altimeter
• Chinese Tiangong-2 space laboratory
• wide-swath ocean topography
• traditional interferometric synthetic aperture radar
• digital elevation model
• land surface
• ocean surface
• interferometric phase noise
• ocean height measurements
• traditional InSAR
• height error
• interferometric imaging radar altimeter
• Ku-band interferometric radar