摘要
高光谱分辨率激光雷达(HSRL)具有无需雷达比先验假设、探测信噪比高的优势,但由于其对出射激光频率及鉴频器稳定性要求严格,目前还未获得广泛应用。基于误差传递方法分析了HSRL频率波动引起的探测误差,提出了一种基于层次识别的分子透过率定标方法,通过实时定标校正HSRL系统鉴频性能波动引起的探测误差,提高探测精度。使用该方法对北京地区的观测数据进行了校正,该方法得到的数据与被动遥感仪器得到的数据的拟合相关度为0.94,证明了该方法有效提高了探测精度。
Objective Among the myriad factors influencing climate change,the interaction between clouds and aerosols is the most uncertain element in global climate dynamics,and is widely acknowledged as a formidable challenge in atmospheric science.Highspectralresolution lidar(HSRL)observations of vertical distribution characteristics of clouds and aerosols,independent of assumptions about cloud vertical structure and lidar ratio,hold immense scientific potential for future research on cloudaerosol interactions.In HSRL systems,active frequency locking technology is typically employed to match the emitted laser wavelength with the etalon,thus ensuring system parameter stability.However,changes in the working environment or hardware failures can reduce the locking precision to significantly degrade the highspectralresolution detection performance.Therefore,realtime calibration of molecular transmittance,correction of detection results,and enhancement of detection accuracy are of paramount significance.Methods In the HSRL system,the molecular transmittance is determined by the collaboration of multiple components such as the emitted laser and the etalon.Groundbased lidar observations are susceptible to environmental changes,which require timely calibration for accurate inversion.The atmosphere is replete with a multitude of components such as clouds and aerosols,necessitating stratified identification.Distinguishing between clouds,aerosols,and clean areas in the atmosphere lays the foundation for calibrating molecular transmittance.We introduce an online method for calibrating molecular transmittance,which avoids interference from clouds and aerosols by stratified identification to achieve online calibration of molecular transmittance.Since the proposed HSRL can directly invert atmospheric optical property parameters without assuming a lidar ratio,the utilization of a scattering ratio threshold method for classification provides unique advantages.Results and Discussions The experiment selects calibration cases in three distinct atmospheric conditions in Beijing,including clear,dusty,and cloudy conditions.Under these different atmospheric states,molecular transmittance calibration can be performed by following atmospheric stratified identification,which demonstrates that this method can calibrate molecular transmittance in various weather conditions.To verify the accuracy of the HSRL detection results,we compare the HSRL with the widely employed sun photometer.The observation results in Beijing are inverted by adopting both fixed molecular transmittance and online calibration parameters.When fixed parameters are leveraged for inversion,the correlation coefficient of the detection results of the two instruments is 0.92,and the root mean square error is 0.136.After conducting correction with this method,some inversion errors are effectively corrected,the correlation coefficient reaches 0.94,and the root mean square error decreases to 0.078.The detection results obtained from the inversion show higher consistency with that of the sun photometer.Conclusions We initially analyze the molecular transmittance error based on the fundamental principles and detection methods of HSRL.In the HSRL system,where an iodine molecule absorption cell serves as a spectral etalon,the systematic error in molecular transmittance primarily results from the frequency fluctuation of the emitted laser and temperature instability in the molecular absorption cell.Meanwhile,an online calibration method for molecular transmittance is proposed to rectify the influence caused by system instability.Unlike the calibration method that fixes clean atmospheric areas,this method exploits the HSRL characteristics that can simply and accurately invert the backscatter ratio,and employs the backscatter ratio as the basis for stratified identification.Additionally,after selecting clean areas in the atmosphere,the molecular transmittance is calibrated by adopting these clean areas.This leads to the result that transmittance calibration cannot be limited to clear weather,thus supplementing the calibration method in nonclear weather conditions.Finally,based on the observation results of the HSRL system in Beijing,an analysis of its observation results is conducted to demonstrate the effectiveness of this method in enhancing detection accuracy.
作者
吴凌云
梁宇辰
陈非同
蒋铖冲
陈楚霄
刘崇
孙文波
万学平
邓志吉
刘明
程淼
符哲蔚
吴兰
项震
刘东
Wu Lingyun;Liang Yuchen;Chen Feitong;Jiang Chengchong;Chen Chuxiao;Liu Chong;Sun Wenbo;Wan Xueping;Deng Zhiji;Liu Ming;Cheng Miao;Fu Zhewei;Wu Lan;Xiang Zhen;Liu Dong(College of Optical Science and Engineering,Zhejiang University,Hangzhou 310027,Zhejiang,China;Donghai Laboratory,Zhoushan 316021,Zhejiang,China;Wuxi Zhongke Optoelectronic Technology Corporation,Wuxi 214111,Jiangsu,China;Zhejiang Dahua Technology Co.,Ltd.,Hangzhou 310057,Zhejiang,China;ZJUHangzhou Global Scientific and Technological Innovation Center,Hangzhou 311200,Zhejiang,China)
出处
《光学学报》
CSCD
北大核心
2024年第24期23-30,共8页
Acta Optica Sinica
基金
国家重点研发计划(2022YFB3901704)
中央高校基本科研业务费专项资金(226-2023-00138)
中央引导地方科技发展资金(2023ZY1004)
东海实验室预研项目(DH2022ZY0003)。
