Analysis Of Influencing Factors On The Parameters Of The Satellite Radar Altimeter In High Sea Condition

Hurricanes and typhoons rainstorm extreme atmospheric and sea state(or high sea states) leads to the sea wave breaking, thus in the sea formed a large number of whitecaps and bubble(referred to as foam). In usually sea conditions and radar altimeter will rule of sea echo waveform is received, according to the ocean model(brown) model can more accurate inversion of sea surface parameters, and can meet the requirement of engineering practice. However, when a high state of the sea, due to the foam and rainfall of microwave signal attenuation and scattering, resulting in the altimeter received microwave signal is very weak, even loss of lock, which greatly affect the altimeter sea surface parameters inversion and its accuracy.This paper mainly studied the effects of high sea foam and rainfall on inversion of ocean parameters altimeter. First analysis of the satellite radar altimeter measurement model and basic principle. Secondly, detailed analysis and study the influence of rainfall on altimeter parameter inversion. Research on Rainfall on microwave attenuation and Mie scattering theory, radiation measuring rainfall, liquid water principle, based on discussed the rainfall on the altimeter to the influence of scattering coefficient inversion,to analyze the effect of foam on the sea surface wind speed retrieval. Then, a detailed study of the effects of foaming parameters inversion of altimeter:(1) based on air-Foam- water three layers medium model, using the theory of electromagnetic field calculation and analysis of the model of the electromagnetic wave reflection characteristics, so as to obtain the foam in the presence of sea surface reflectance characteristics, and foam on the sea to the scattering coefficient and the effect of error correction value.(2) on the basis of this, according to the empirical relation of foam coverage and wind speed, wind speed and to the relationship between the scattering coefficient, discussed the effect of foam on the altimeter sea surface wind speed retrieval.(3) foam height to the effects of inversion analysis is starting from the height of echo waveform, discuss the influence the effect of foam on the sea surface height probability density function, the echo waveform, by the method of least squares fitting inversion height, to get the foam height to the inversion of the influencing characteristics and error correction value. Finally, through the iterative algorithm on scattering coefficient measurement of rainfall and the existing foam after correction.The results of this research has a good reference value and application significance in altimeter high sea parameter inversion and correction work.