CN-122017775-A - Method and system for accurately estimating interference baseline inclination angle of wide swath altimeter

CN122017775ACN 122017775 ACN122017775 ACN 122017775ACN-122017775-A

Abstract

The invention discloses a method and a system for accurately estimating interference baseline inclination angles of a wide swath altimeter, wherein the method comprises the steps of setting a search range based on the fact that a satellite rolling angle is an initial value of the interference baseline inclination angle, selecting N inclination angles in the search range, respectively carrying out sea surface altitude inversion on right side view and left side view observation data of the altimeter, carrying out averaging along azimuth directions to obtain right side view and left side view one-dimensional altitude vectors, each vector comprises altitude values corresponding to M distance doors, further obtaining right side view and left side view matrixes, carrying out differential operation along column directions to obtain right side view differential matrixes and left side view differential matrixes, calculating absolute values of sum of the two differential matrixes to obtain absolute value matrixes, searching each column minimum value, taking the inclination angles corresponding to the minimum value as preliminary estimation values of each distance door, carrying out error correction to obtain corrected inclination angle estimation values, and carrying out averaging on the inclination angle estimation values after all the distance doors to obtain a final interference baseline inclination angle estimation value.

Inventors

ZHAI WENSHUAI
ZHANG YUNHUA
DONG XIAO
Kang Xueyan

Assignees

中国科学院国家空间科学中心

Dates

Publication Date: 20260512
Application Date: 20260114

Claims (7)

1. A method of accurately estimating a wide swath altimeter interference baseline tilt angle, comprising: Step 1, setting a search range by taking an initial value of an interference baseline inclination angle as the initial value based on a satellite rolling angle measured by a satellite attitude measuring instrument, and selecting N inclination angles in the search range; Step 2, sea surface height inversion is carried out on the right side view observation data and the left side view observation data of the altimeter respectively, and two-dimensional sea surface heights obtained by inversion are averaged along azimuth directions to obtain right side view one-dimensional height vectors and left side view one-dimensional height vectors, wherein each vector comprises height values corresponding to M distance doors; Step 3, respectively carrying out differential operation on the right side view matrix and the left side view matrix along the column direction to obtain a right side view differential matrix and a left side view differential matrix; searching the minimum value of each column of the absolute value matrix, and taking the corresponding inclination angle value as the preliminary estimated value of each distance gate; Step 5, performing error correction on the preliminary estimated value of each range gate to obtain a corrected inclination angle estimated value; And 6, averaging the corrected inclination angle estimated values of all the range gates to obtain a final interference baseline inclination angle estimated value.
2. The method for precisely estimating the interference baseline tilt of a wide swath altimeter according to claim 1, wherein the initial value of step 1 is The search range is Selecting N dip angle values in the search range ,i=1,2,...N, 。
3. The method for precisely estimating the interference baseline tilt of a wide swath altimeter according to claim 2, wherein the right side view matrix obtained in the step 2 is recorded as The left side view matrix is denoted as , wherein, Represents the j-th range gate, j=1, 2.
4. A method of accurately estimating interference baseline tilt of a wide swath altimeter according to claim 3, the right side view differential matrix of step 3 And left side view differential matrix The method comprises the following steps of: ; ; Wherein, the For the i+1th row, the j-th column element, The (i+1) th row and the (j) th column of the left side view differential matrix.
5. The method for accurately estimating interference baseline tilt of wide swath altimeter according to claim 1, said step 5 obtaining corrected tilt estimate The method comprises the following steps: ; Wherein, the For the preliminary estimate of the j-th range gate obtained in step 4, For the difference in average sea level model height at the jth range gate, For the j-th range gate, As a satellite orbit height, the satellite orbit height, For the radius of the earth, The altimeter view angle corresponding to the jth range gate.
6. The method for precisely estimating interference baseline tilt of wide swath altimeter according to claim 5, said step 6 obtaining a final interference baseline tilt estimate The method comprises the following steps: 。
7. a system for accurately estimating interference baseline tilt of a wide swath altimeter, comprising: the initial module is used for setting a search range by taking the initial value as the center and selecting N dip angles in the search range based on the initial value of the interference baseline dip angle of the satellite rolling angle measured by the satellite attitude measuring instrument; The system comprises an altimeter right side view observation data and left side view observation data, an inversion and averaging module, a left side view matrix, a right side view matrix, a left side view matrix and a left side view matrix, wherein the altimeter right side view observation data and the left side view observation data are respectively subjected to sea surface altitude inversion, the two-dimensional sea surface altitudes obtained by inversion are averaged along azimuth directions to obtain right side view one-dimensional altitude vectors and left side view one-dimensional altitude vectors, each vector comprises height values corresponding to M distance gates; the differential and calculation module is used for carrying out differential operation on the right side view matrix and the left side view matrix along the column direction to obtain a right side view differential matrix and a left side view differential matrix; The estimating module is used for searching the minimum value of each column of the absolute value matrix and taking the corresponding inclination angle value as the preliminary estimated value of each distance gate; a correction module for performing error correction on the preliminary estimated value of each range gate to obtain corrected inclination angle estimated value, and And the output module is used for averaging the corrected inclination angle estimated values of all the range gates to obtain a final interference baseline inclination angle estimated value.

Description

Method and system for accurately estimating interference baseline inclination angle of wide swath altimeter Technical Field The invention belongs to the technical field of satellite-borne microwave remote sensing, and particularly relates to a method and a system for accurately estimating interference baseline dip angle of a wide swath altimeter. Background The satellite-borne radar altimeter is a very important ocean microwave remote sensor, is mounted on a satellite, and can accurately measure global sea level height, and the measurement accuracy reaches the centimeter level. The wide swath altimeter is a novel satellite-borne radar altimeter developed in recent years, is represented by a Tiangong No. two three-dimensional imaging altimeter and an SWOT satellite Ka wave band radar interferometer, adopts a small-incidence angle short baseline interferometry technology, realizes sea surface measurement of high resolution and wide swath, observes the swath to reach tens of kilometers to hundreds of kilometers, greatly improves the observation efficiency of the altimeter, and can also meet the observation requirement of sub-mid-scale ocean phenomena. To realize high-precision measurement of sea surface height, the wide swath altimeter must accurately know the value of the interference baseline inclination angle, and the error needs to be smaller than the magnitude of an angle second, and some of the errors even need to reach the magnitude of 10 -2 angle seconds. In general, the tilt angle of the interference baseline of the wide swath altimeter is equal to the roll angle of the satellite attitude, and the measurement can be performed in real time by the satellite attitude measuring instrument, but the measurement accuracy hardly meets the requirement of the altimeter on the tilt angle error, and the calibration or estimation needs to be performed by combining other methods. For example, the external calibration method has high requirements on ground control points, is difficult to realize and can not be frequently revisited, and can also utilize altimeter observation data to carry out multi-parameter joint estimation including interference baseline inclination angle, but the method has large complex operation amount and is easily influenced by other parameters. The wide swath altimeter has a single-side view system and a double-side view system, and the development trend of the wide swath altimeter is that the wide swath altimeter is developed from the single-side view to the double-side view. Both of the above methods are applicable to both single-sided and double-sided wide swath altimeters. The method is applicable to the double-side view wide swath altimeter, the inclination angle estimation is carried out based on the characteristic that the inclination angle error of an interference base line is just the opposite quantity in the left side view and the right side view, but the method is only applicable to ideal situations, namely, the sea surface to be observed is in a windless and wave-free state, the sea surface height trends on the two sides are consistent, in practice, the ideal situation is rarely existed, the estimation method can generate non-negligible error, and for the new generation wide swath altimeter, the precision of the method can not meet the requirement and can not be applied in practice. Thus, there is an urgent need for a method of accurately estimating the interference baseline tilt of a wide swath altimeter. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a method for accurately estimating the interference baseline inclination angle of a wide swath altimeter, which is easy to realize and has high precision in practical application. In view of this, the present invention proposes a method for accurately estimating the interference baseline inclination of a wide swath altimeter, comprising: Step 1, setting a search range by taking an initial value of an interference baseline inclination angle as the initial value based on a satellite rolling angle measured by a satellite attitude measuring instrument, and selecting N inclination angles in the search range; Step 2, sea surface height inversion is carried out on the right side view observation data and the left side view observation data of the altimeter respectively, and two-dimensional sea surface heights obtained by inversion are averaged along azimuth directions to obtain right side view one-dimensional height vectors and left side view one-dimensional height vectors, wherein each vector comprises height values corresponding to M distance doors; Step 3, respectively carrying out differential operation on the right side view matrix and the left side view matrix along the column direction to obtain a right side view differential matrix and a left side view differential matrix; searching the minimum value of each column of the absolute value matrix, and taking the corresponding inclinat