| Global precipitation is very important for global climate and environment change research, sustainable development, production activities and ordinary life of human being. Spaceborne precipitation radar is a powerful tool for global precipitation measurement. It not only has the capability of directly measurementing three dimensional structure of precipitation, but also provides reference for wide swath precipitation retrieval by passive microwave readimetry.In this dissertation, key issues of the precipitation radar techniques appropriate to spaceborne application are studied, including pulse waveform design, pulse compression and range sidelobe suppression, signal processing, special resolution enhancement, attenna selection, adaptive scanning, etc.The model of surface clutter interference with spaceborne pulse-compression precipitation radar is built for the first time. Sea clutter modle with considering the effect of range weighting function is formulated.A novel technique for pulse compression with emphasis on the suppression of range sidelobes is proposed, with which the achieved peak range sidelobe level can be less then -110 dB. With this new technique, it is avoided that the high power amplifier can only operate in nonsaturated status which leads to the degradation of efficiency when compressing chirp signal. According to the results of analysis, the achieved range sidelobe is insensitive to Doppler shifts.Signal processing methods to obtain precipitation parameters including rain rate, rainfall velocity and polarimetric information are analyzed in detail. A new method—supper resolution reconstruction with BG inversion method is proposed to release the non-uniform beam-filling effects on rain rate estimations.Finally, performance parameters for future spaceborne precipitation radar are discussed.
|
PDF Full Text Request