基于CALIPSO星載激光雷達的邊界層高度探測研究
發(fā)布時間：2019-06-12 12:27
【摘要】：氣溶膠對人體健康、環(huán)境污染以及交通運輸?shù)犬a生著重要的影響。近年來大氣污染問題比較突出。大氣邊界層作為與地表交互最為密切的大氣,它與污染物進行著交互作用。因此,針對邊界層的研究一直是國內外研究的一個熱點問題,而邊界層其中一個重要的特征即是邊界層高度,也稱為混合層高度,它是大氣探測中的一個重要內容。但是傳統(tǒng)的邊界層高度測量方式空間覆蓋度低,重復頻率低或者精度低,針對這個不足,激光雷達作為主動的探測技術由于其全天時,高時間和垂直分辨率、能夠連續(xù)探測大氣等特點,發(fā)展成為一種有效的PBLH(Planetary boundary layer height)探測手段。除此之外,近十一年來,基于CALIPSO(Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations)星載激光雷達的PBLH探測也在逐漸的發(fā)展起來。相比于地基激光雷達,CALIPSO在空間覆蓋上具有獨特的優(yōu)勢。由于CALIPSO獲取的信號信噪比低,本研究通過星載激光雷達的回波信號仿真分析,討論了星載激光雷達系統(tǒng)參數(shù)對回波信號信噪比的影響,并通過改變累加脈沖,進行平滑效果分析。對CALIPSO的PBLH反演方法進行了探討。目前,利用CALIPSO進行PBLH的反演時,主要采用的是最大方差法,但該方法本身存在PBLH誤判的情況。此外,在面對不同的大氣污染條件時,該方法還存在限制。最大方差法適用于清潔天氣和部分卷云對流的情況,在邊界層內有著高后向散射的混濁大氣的情況,小波協(xié)方差方法則更為適用。本文對最大方差法通過增加判別條件的方式進行了改進,同時通過小波分析方法和最大方差法兩者相結合的方式,發(fā)展了適用于不同大氣氣溶膠條件的綜合PBLH探測算法,基于CALIPSO的觀測,利用該算法反演得到中國區(qū)域的PBLH結果。選取六個典型地點,對中國典型區(qū)域的PBLH時序變化進行分析。通過中國區(qū)域的季節(jié)和年際變化分析,結果表明了PBLH在時間和空間上的分布特點。之后,利用ECMWF(European Center for Medium range Weather Forecasting)的再分析產品,對中國區(qū)域的PBLH進行了季節(jié)和年際變化分析,并與CALIPSO的相應結果進行了對比分析。論文主要的研究結論有:(1)利用地基激光雷達對北京站點上空的PBLH進行了探測,并進行不同污染狀況下、多年日變化和多年季節(jié)變化的PBLH分析,結果顯示PBLH在不同時間和大氣污染狀況下,呈現(xiàn)出一定的分布特點。(2)星載激光雷達的仿真分析表明,激光發(fā)射能量,接收口徑大小,累加脈沖與信噪比成正相關,而濾波寬度,接收視場角大小和采樣頻率與信噪比成反相關。通過累加脈沖的平滑結果,表明回波信號的信噪比與平滑尺度成正相關,但隨著平滑尺度的增大,回波信號的水平分辨率也在逐漸的降低。(3)利用地基激光雷達站點的觀測,對CALIPSO獲取的PBLH進行了驗證。結果顯示,對于Lille地基激光雷達站點,在無云的大氣條件下,PBLH的平均絕對誤差為206米,在懸浮層去掉后,平均誤差為106米。對于Beijing地基激光雷達站點,它與CALIPSO的地面軌跡之間的平均距離超過40 km,PBLH的平均絕對誤差為0.5 km。(4)基于CALIPSO的觀測,利用綜合的PBLH反演算法,獲取了中國區(qū)域的PBLH。通過6個典型地點的PBLH的時序變化分析,反映了中國典型區(qū)域的大氣污染狀況。而中國區(qū)域的年變化和季節(jié)變化結果表明,PBLH具有明顯的季節(jié)變化特征,春、夏季PBLH數(shù)值高,而秋、冬季數(shù)值低,PBLH的年際變化則不明顯。通過對比ECMWF再分析資料獲取的PBLH結果,發(fā)現(xiàn)兩者之間差異較大。最后,利用由CALIPSO獲取的PBLH對ECMWF的相應結果進行訂正。
[Abstract]:The aerosol has an important influence on human health, environmental pollution and transportation. In recent year, that problem of air pollution is relatively prominent. The atmospheric boundary layer is the most closely related to the surface, and it interacts with the pollutants. Therefore, the study of the boundary layer has been a hot issue at home and abroad, and one of the most important features of the boundary layer is the height of the boundary layer, also known as the height of the mixed layer, which is an important part of the atmospheric sounding. but the traditional boundary layer height measuring method has the advantages of low space coverage, low repetition frequency or low precision, and aiming at the defect, the laser radar can continuously detect the atmosphere and the like due to the high time and the vertical resolution of the laser radar as the active detection technology, The development is an effective means of detection of the PBLH. In addition, the PBLH detection of the on-board laser radar based on the CALIPSO (Cloud-Aerosol Lidar and red Pathfinder Satellite Observation) has also been gradually developed for nearly a year. Compared with the ground lidar, the CALIPSO has a unique advantage over the space coverage. Since the signal-to-noise ratio of the signal obtained by CALIPSO is low, the influence of the parameters of the spaceborne laser radar system on the signal-to-noise ratio of the echo signal is discussed through the simulation and analysis of the echo signal of the satellite-borne laser radar, and the smoothing effect analysis is performed by changing the accumulated pulse. The PBLH inversion method for CALIPSO is discussed. At present, when using CALIPSO to carry out the inversion of the PBLH, the maximum variance method is mainly used, but the method itself is the case of the PBLH misjudgment. In addition, the method also has limitations in the face of different atmospheric conditions. The maximum variance method is suitable for the case of clean weather and partial volume cloud convection, and the wavelet covariance method is more applicable to the case of high-backward scattering of the turbid atmosphere in the boundary layer. In this paper, the method of maximum variance is improved by increasing the discrimination condition, and a comprehensive PBLH detection algorithm for different atmospheric aerosol conditions is developed by combining the wavelet analysis method and the maximum variance method, and based on the observation of CALIPSO, The result of PBLH in the Chinese region is obtained by using the algorithm. Six typical locations are selected for analysis of the PBLH timing changes in the typical region of China. Through the analysis of the seasonal and interannual variation of China's region, the distribution of PBLH in time and space is shown. Then, using the re-analysis of ECMWF (European Center for Medium range Weather Forecast), the seasonal and interannual change of PBLH in China's region was analyzed and compared with the corresponding results of CALIPSO. The main conclusions of this paper are as follows: (1) Using the ground lidar to detect the PBLH over the Beijing site, and to carry on the analysis of the PBLH with different pollution, for many years and for many years, the results show that the PBLH is under different time and air pollution. And has a certain distribution characteristic. (2) The simulation analysis of the satellite-borne laser radar shows that the laser emission energy, the size of the receiving aperture, the accumulation pulse and the signal-to-noise ratio are positively correlated, and the filter width, the receiving field angle size and the sampling frequency are inversely related to the signal-to-noise ratio. The result of the smoothing of the accumulated pulse indicates that the signal-to-noise ratio of the echo signal is positively correlated with the smoothing scale, but with the increase of the smooth scale, the horizontal resolution of the echo signal is gradually reduced. (3) The PBLH acquired by CALIPSO was verified by the observation of the ground laser radar site. The results show that for the Lille foundation laser radar site, the mean absolute error of PBLH is 206 m, and the average error is 106 m after the suspension layer is removed. For the Bejing foundation laser radar station, the average distance between it and the ground track of CALIPSO exceeds 40 km and the mean absolute error of PBLH is 0.5 km. (4) Based on the observation of CALIPSO, the PBLH in China is obtained by using the comprehensive PBLH inversion algorithm. The situation of atmospheric pollution in the typical region of China is reflected by the analysis of the time-series of the PBLH in six typical locations. The annual change and the seasonal change of the Chinese region show that the PBLH has obvious seasonal change characteristics, and the PBLH value in the spring and summer is high, and in autumn and winter, the interannual variation of the PBLH is not obvious. The results of the PBLH obtained by comparing the ECMWF re-analysis data revealed a large difference between the two. Finally, the corresponding results of ECMWF were revised using the PBLH obtained by CALIPSO.
【學位授予單位】：中國科學院大學(中國科學院遙感與數(shù)字地球研究所)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X831
本文編號：2498019
[Abstract]:The aerosol has an important influence on human health, environmental pollution and transportation. In recent year, that problem of air pollution is relatively prominent. The atmospheric boundary layer is the most closely related to the surface, and it interacts with the pollutants. Therefore, the study of the boundary layer has been a hot issue at home and abroad, and one of the most important features of the boundary layer is the height of the boundary layer, also known as the height of the mixed layer, which is an important part of the atmospheric sounding. but the traditional boundary layer height measuring method has the advantages of low space coverage, low repetition frequency or low precision, and aiming at the defect, the laser radar can continuously detect the atmosphere and the like due to the high time and the vertical resolution of the laser radar as the active detection technology, The development is an effective means of detection of the PBLH. In addition, the PBLH detection of the on-board laser radar based on the CALIPSO (Cloud-Aerosol Lidar and red Pathfinder Satellite Observation) has also been gradually developed for nearly a year. Compared with the ground lidar, the CALIPSO has a unique advantage over the space coverage. Since the signal-to-noise ratio of the signal obtained by CALIPSO is low, the influence of the parameters of the spaceborne laser radar system on the signal-to-noise ratio of the echo signal is discussed through the simulation and analysis of the echo signal of the satellite-borne laser radar, and the smoothing effect analysis is performed by changing the accumulated pulse. The PBLH inversion method for CALIPSO is discussed. At present, when using CALIPSO to carry out the inversion of the PBLH, the maximum variance method is mainly used, but the method itself is the case of the PBLH misjudgment. In addition, the method also has limitations in the face of different atmospheric conditions. The maximum variance method is suitable for the case of clean weather and partial volume cloud convection, and the wavelet covariance method is more applicable to the case of high-backward scattering of the turbid atmosphere in the boundary layer. In this paper, the method of maximum variance is improved by increasing the discrimination condition, and a comprehensive PBLH detection algorithm for different atmospheric aerosol conditions is developed by combining the wavelet analysis method and the maximum variance method, and based on the observation of CALIPSO, The result of PBLH in the Chinese region is obtained by using the algorithm. Six typical locations are selected for analysis of the PBLH timing changes in the typical region of China. Through the analysis of the seasonal and interannual variation of China's region, the distribution of PBLH in time and space is shown. Then, using the re-analysis of ECMWF (European Center for Medium range Weather Forecast), the seasonal and interannual change of PBLH in China's region was analyzed and compared with the corresponding results of CALIPSO. The main conclusions of this paper are as follows: (1) Using the ground lidar to detect the PBLH over the Beijing site, and to carry on the analysis of the PBLH with different pollution, for many years and for many years, the results show that the PBLH is under different time and air pollution. And has a certain distribution characteristic. (2) The simulation analysis of the satellite-borne laser radar shows that the laser emission energy, the size of the receiving aperture, the accumulation pulse and the signal-to-noise ratio are positively correlated, and the filter width, the receiving field angle size and the sampling frequency are inversely related to the signal-to-noise ratio. The result of the smoothing of the accumulated pulse indicates that the signal-to-noise ratio of the echo signal is positively correlated with the smoothing scale, but with the increase of the smooth scale, the horizontal resolution of the echo signal is gradually reduced. (3) The PBLH acquired by CALIPSO was verified by the observation of the ground laser radar site. The results show that for the Lille foundation laser radar site, the mean absolute error of PBLH is 206 m, and the average error is 106 m after the suspension layer is removed. For the Bejing foundation laser radar station, the average distance between it and the ground track of CALIPSO exceeds 40 km and the mean absolute error of PBLH is 0.5 km. (4) Based on the observation of CALIPSO, the PBLH in China is obtained by using the comprehensive PBLH inversion algorithm. The situation of atmospheric pollution in the typical region of China is reflected by the analysis of the time-series of the PBLH in six typical locations. The annual change and the seasonal change of the Chinese region show that the PBLH has obvious seasonal change characteristics, and the PBLH value in the spring and summer is high, and in autumn and winter, the interannual variation of the PBLH is not obvious. The results of the PBLH obtained by comparing the ECMWF re-analysis data revealed a large difference between the two. Finally, the corresponding results of ECMWF were revised using the PBLH obtained by CALIPSO.
【學位授予單位】：中國科學院大學(中國科學院遙感與數(shù)字地球研究所)
【學位級別】：博士
【學位授予年份】：2017
【分類號】：X831
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