Satellite radar altimetric waveform resetting method based on waveform derivatives

Abstract

The invention discloses a satellite radar altimetric waveform resetting method based on waveform derivatives. The method comprises the steps that a first-order derivative and a second-order derivativeof an echo waveform are deduced based on a theoretical echo model; a computational formula of a leading edge midpoint is obtained by use of a waveform leading edge slope maximum value obtained when the second-order derivative is equal to zero; a fitting mode is utilized to solve unknown parameters in the computational formula of the leading edge midpoint, and the position of the leading edge midpoint is determined; a reset distance corrected value is determined according to a preset tracking gate; and sea surface height reset through the resetting method is further calculated according to thereset distance corrected value and an altimetric error corrected value. Through the method, the quality of satellite altimetric data can be improved, the precision of the reset sea surface height ishigher than that obtained through a conventional resetting method, and the correlation between the reset sea surface height and geoidal surface height is obviously improved.

Description

technical field [0001] The invention belongs to the technical field of satellite altimetry, and relates to a method for resetting satellite radar altimetry waveforms based on waveform derivatives. Background technique [0002] The satellite altimetry technology developed since the 1970s uses the microwave radar altimeter on the satellite to measure the distance from the satellite to the sea surface, the effective wave height and the backscatter coefficient in real time, and obtain a large amount of ocean data. Oceanography, oceanography, geophysics, etc. provided basic data. [0003] In order to obtain high-quality altimetry data, geophysical and propagation medium corrections and echo signal processing are required. In the past ten years, although geophysics and propagation medium correction have made great progress, it is still a challenge to obtain a high-precision sea surface height, especially for the processing of echo signals (waveform re-tracking). Because the echo...

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Problems solved by technology

[0005] The resetting algorithm based on empirical statistics is an algorithm that relies on observation and actual experience. For example, the Threshold algorithm determines the threshold coefficient based on empirical formulas. It has strong adaptability and stable results, but the selection of the threshold coefficient has no clear physical meaning and lacks principle. Detailed analysis of interpretation and performance; resetting algorithms based on function fitting, such as the β parameter algorithm, which takes into account the physical mechanism of the waveform and selects parameters with a certain physical meaning to fit the waveform. This algorithm has high calculation accuracy, but parameter calculation requires iteration , the termination condition of the iteration will affect the final parameter estimation, and the calculated parameters will deviate from the actual meaning. These factors may make it impossible to solve the relevant parameters; the resetting algorithm based on waveform wavelet analysis is to deal with the waveform of multiple leading edges, and determine through data comparison The most accurate re-distance, but it is very difficult to judge and select the wavelet

[0006] Due to the complexity of the echo waveform, the current rescheduling method cannot satisfy various echo waveforms, and the rescheduling accuracy of different rescheduling methods is also different. Therefore, the existing waveform rescheduling method needs to be further improved

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