Large inland lake and wetland water level inversion method based on satellite altimetry data

Abstract

The invention relates to a large inland lake and wetland water level inversion method based on satellite altimetry data. The method comprises the steps that echo data is preprocessed, a dominant riseleading edge in an echo waveform obtained after preprocessing is extracted, and echo waveform resetting is performed; continuous echo data in multiple trajectories are arbitrarily selected in a research region, different thresholds are used to perform echo resetting, and improved values corresponding to reset echoes are calculated; the maximum improved value is found out, and the threshold corresponding to the maximum improved value is used as an optimal threshold; the optimal threshold is used to perform echo waveform resetting, and water levels are calculated; all the water levels in the research region are post-processed; and last, data verification is performed on time-sequence water levels, whether precision obtained after data verification is within an allowed range or not is judged,and if yes, the time-sequence water levels are output; or otherwise echo resetting is continued. The water level inversion method is simple in calculation, high in speed and high in precision.

Description

technical field [0001] The invention relates to the field of data measurement, in particular to a large-scale inland lake and wetland water level inversion method based on satellite altimetry data. Background technique [0002] Large inland lakes and wetlands provide important habitats for wild animals and plants and have irreplaceable ecological functions. However, due to their large area, complex geographical environment, and large seasonal changes in water levels, it has brought great difficulties to water level research. . Traditional water level measurement is mainly done by hydrological stations, which have the advantages of high measurement accuracy and continuous access to water level information, but the disadvantages are also obvious. Hydrological stations are expensive to maintain and can only be measured from point to area, and large inland lakes and wetlands are generally located in remote locations. In underdeveloped areas, due to the constraints of economic f...

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Problems solved by technology

[0005] However, in the above-mentioned patent, since the satellite altimetry data is directly substituted into the lake altimetry formula for calculation of the lake water level, the echo data in the satellite altimetry data is not processed, and the method does not take into account the water level in the offshore area. , Due to the impact of coastal land terrain, islands, tides, geophysical factors and instrument hardware, the reflected waveform of the satellite altimetry pulse is irregular

[0006] At present, in the existing technology, satellite altimetry waveform resetting methods include OCOG algorithm, Ice2 algorithm, Threshold algorithm and improved Threshold algorithm. The OCOG algorithm first finds the center of gravity of each returned waveform, and calculates the waveform amplitude and width numerically. The calculation method is simple and convenient, but because the OCOG algorithm uses all the waveform data, and when the waveform is affected by coastal terrain, geophysical factors, hardware, and deviation from the sub-satellite point, the waveform contains large Noise, so the algorithm is greatly affected by noise, and the calculated sea surface has low precision; the Ice2 algorithm resets the echo waveform of the ice sheet, and is mainly used in the ice sheet area; the Threshold algorithm gives the threshold value based on the amplitude and maximum waveform sampling, etc. , linear interpolation is performed between several adjacent sampling values ​​intersecting the threshold with the steep part of the leading edge to determine the relocation point, but the threshold value determination in this algorithm is inaccurate and has a large error; in the improved Threshold algorithm First conduct waveform analysis to find all the sub-waveforms contained in the waveform, and then use the improved waveform formula for resetting. In this algorithm, one waveform may determine multiple leading edges, and calculate the distance correction after multiple resetting, but for multiple Auxiliary data is still needed for how to choose after the leading edge rescheduling, so the algorithm needs to use different sub-waveform judgment standards for different altimetry satellites, and cannot directly determine the optimal result, and the calculation is complicated, which needs further improvement

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