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CN-122019968-A - Microwave radiometer fringe elimination pretreatment method based on moving median smoothing

CN122019968ACN 122019968 ACN122019968 ACN 122019968ACN-122019968-A

Abstract

The invention discloses a moving median smoothing-based microwave radiometer streak elimination pretreatment method which comprises the following steps of 1, adopting a microwave radiometer to carry out circular scanning, respectively obtaining a heat source count value C w , a cold source count value C c , an observation target count value C e , a heat source bright temperature T w and a cold source bright temperature T c , 2, respectively carrying out moving median noise smoothing on a heat source observation count value C w and a cold source count value C c between scanning lines to obtain a smoothed heat source observation count value and a cold source count value, and 3, carrying out two-point calibration by utilizing the heat source bright temperature T w obtained in the step 1, the cold source bright temperature T c and the smoothed heat source observation count value and the cold source count value obtained in the step 2 to obtain an observation target bright temperature T e after streak elimination. The method can effectively solve the problem of influence of stripe noise on the data quality of the microwave radiometer in the existing stripe elimination method.

Inventors

  • REN HE
  • LI YINAN
  • JIN XU
  • WANG CONGCONG
  • GAO WENYU
  • CHEN WENXIN
  • LI HAO

Assignees

  • 西安空间无线电技术研究所

Dates

Publication Date
20260512
Application Date
20251231

Claims (5)

  1. 1. A microwave radiometer fringe elimination pretreatment method based on moving median smoothing is characterized by comprising the following steps: Step 1, performing circumferential scanning by adopting a microwave radiometer to respectively obtain a heat source count value C w , a cold source count value C c , an observation target count value C e , a heat source bright temperature T w and a cold source bright temperature T c ; Step 2, smoothing moving median noise between scanning lines is respectively carried out on the heat source observation count value C w and the cold source count value C c , and a smoothed heat source observation count value and a smoothed cold source count value are obtained; And 3, performing two-point calibration by using the heat source bright temperature T w and the cold source bright temperature T c obtained in the step 1 and the smoothed heat source observation count value and the cold source count value obtained in the step 2 to obtain the observation target bright temperature T e after eliminating stripes.
  2. 2. The pretreatment method for eliminating streaks by microwave radiometer based on moving median smoothing as claimed in claim 1, wherein in step 1, for the mth scanning line, the obtained 4 heat source count values are C wm,1 ,C wm,2 ,C wm,3 ,C wm,4 , the 4 heat source bright temperatures are T wm,1 ,T wm,2 ,T wm,3 ,T wm,4 , the 4 cold source count values are C cm,1 ,C cm,2 ,C cm,3 ,C cm,4 , the 4 cold source bright temperatures are T cm,1 ,T cm,2 ,T cm,3 ,T cm,4 , wherein 1≤m, M is the total number of scanning lines, the obtained N-th observation target count value is C em,n , wherein 1≤n, N is the total number of observation targets.
  3. 3. The method for preprocessing a moving median smoothing-based microwave radiometer fringe as recited in claim 2, wherein step 2 comprises the sub-steps of: Step 21, smoothing the 1 st heat source count value of all scan lines, and smoothing the 1 st heat source count value C wm,1 of the m-th scan line to obtain a smoothed heat source count value of The size of the movable median sliding window is k, and k is an odd number; The heat source count value obtained by smoothing the 1 st heat source count value of the mth scanning line is obtained by the following flow Step 211, defining the original data points covered by the moving median sliding window as: Wherein, the left boundary L m and the right boundary R m of the window need to satisfy: (1) When m is far from the edge, i.e. when And is also provided with In the time-course of which the first and second contact surfaces, (2) When m is close to the edge, i.e. when And is also provided with In the time-course of which the first and second contact surfaces, Defining the window to automatically shrink to avoid out-of-bounds, i.e.: Step 212, sorting the data C wj,1 in the window in ascending order, to obtain: Z wj,1 ＝[Z wj,1-1 ,Z wj,1-2 ,…,Z wj,1-p ]; wherein, Z wj,1-1 ≤Z wj,1-2 ≤…≤Z wj,1-p ,p＝R m -L m +1 is the actual data point number of the current window, and p is less than or equal to k; Step 213, calculating a smoothed heat source count value If p is an odd number of times, Wherein t is a positive integer; If p is an even number, Step 22, obtaining smoothed heat source count values of the 2 nd, 3 rd and 4 th heat source count values C wm,2 ,C wm,3 ,C wm,4 of the m-th scanning line according to the same process as step 21 For the 1 st, 2 nd, 3 rd and 4 th cold source count values C cm,1 ,C cm,2 ,C cm,3 ,C cm,4 of the mth scanning line, the smooth cold source count values of the mth scanning line are respectively obtained according to the same treatment of the step 21 and are
  4. 4. A method for pretreatment of moving median smoothing based microwave radiometer fringes elimination as defined in claim 3, wherein in step 21, k has a value of 9.
  5. 5. A moving median smoothing based microwave radiometric streak pretreatment method as in claim 3 wherein step 3 includes the sub-steps of: step 31, calculating the average value of the cold source count values of the mth scanning line Step 32, calculating the mean value of the heat source count values of the mth scanning line Step 33, calculating a scaling coefficient k m ,b m of the mth scan line: Step 34, calculating the observed target bright temperature by using the scaling coefficient of the mth scanning line obtained in step 33, namely the observed target bright temperature after eliminating the stripes corresponding to the mth scanning line: T em,n ＝k m ×C em,n +b m wherein, C em,n is the n-th observation target count value; and 35, traversing all the scanning lines to obtain the bright temperature of the observation target after eliminating the stripes corresponding to all the scanning lines.

Description

Microwave radiometer fringe elimination pretreatment method based on moving median smoothing Technical Field The invention belongs to the technical field of space microwave remote sensing, and particularly relates to a microwave radiometer fringe elimination pretreatment method based on moving median smoothing. Background The microwave radiometer is used for receiving microwave radiation heat of targets such as atmosphere, ocean and the like, realizing the observation of parameters such as atmospheric temperature and humidity profile, ocean salinity and the like, and is core equipment in the fields of weather, agriculture, environment, remote sensing and the like. The pretreatment technology is used as a bridge for connecting the original observed data with the subsequent application, and directly determines the quality of the microwave radiation data and the value of the final application. In microwave radiometer pretreatment studies, streak interference is prevalent. Which appears as a signal deviation along the track direction, forming a visually striped pattern. The influence of stripe noise on the microwave radiometer penetrates through the core links of data quality control, calibration and the like, directly restricts the precision of the subsequent quantitative inversion, and needs to pay important attention. The existing method for eliminating the stripes can be divided into two types, one type is used for processing the brightness temperature after calibration, the stripes are extracted through principal component analysis and set empirical mode decomposition, the other type is used for processing the original count value before calibration, and the count value is processed through rectangular window and triangular window smoothing or spline fitting. The rectangular window and the triangular window are essentially weighted average, the result is obviously pulled by extreme abnormal values in the window, spline fitting is to fit data through polynomial curves, and the abnormal values can lead the curves to deviate from real trends. While the moving median is based on the ordering result of the data within the window, the extreme outliers have little effect on the result. Disclosure of Invention The invention aims to provide a microwave radiometer fringe elimination pretreatment method based on moving median smoothing, which aims to solve the problem of influence of fringe noise on the data quality of a microwave radiometer in the existing fringe elimination method. In order to achieve the above purpose, the present invention adopts the following technical solutions: a microwave radiometer fringe elimination pretreatment method based on moving median smoothing comprises the following steps: Step 1, performing circumferential scanning by adopting a microwave radiometer to respectively obtain a heat source count value C w, a cold source count value C c, an observation target count value C e, a heat source bright temperature T w and a cold source bright temperature T c; Step 2, smoothing moving median noise between scanning lines is respectively carried out on the heat source observation count value C w and the cold source count value C c, and a smoothed heat source observation count value and a smoothed cold source count value are obtained; And 3, performing two-point calibration by using the heat source bright temperature T w and the cold source bright temperature T c obtained in the step 1 and the smoothed heat source observation count value and the cold source count value obtained in the step 2 to obtain the observation target bright temperature T e after eliminating stripes. Further, in step 1, for the mth scan line, the obtained 4 heat source count values are respectively C wm,1,Cwm,2,Cwm,3,Cwm,4, the 4 heat source bright temperatures are respectively T wm,1,Twm,2,Twm,3,Twm,4, the 4 cold source count values are respectively C cm,1,Ccm,2,Ccm,3,Ccm,4, the 4 cold source bright temperatures are respectively T cm,1,Tcm,2,Tcm,3,Tcm,4, wherein M is greater than or equal to 1 and less than or equal to M, M is the total number of scan lines, the obtained nth observation target count value is C em,n, wherein N is greater than or equal to 1 and less than or equal to N, and N is the total number of observation targets. Further, step 2 comprises the following sub-steps: Step 21, smoothing the 1 st heat source count value of all scan lines, and smoothing the 1 st heat source count value C wm,1 of the m-th scan line to obtain a smoothed heat source count value of The size of the movable median sliding window is k, and k is an odd number; The heat source count value obtained by smoothing the 1 st heat source count value of the mth scanning line is obtained by the following flow Step 211, defining the original data points covered by the moving median sliding window as: Wherein, the left boundary L m and the right boundary R m of the window need to satisfy: (1) When m is far from the edge, i.e. when And is also pr