塔中涡动资料不同坐标旋转方法比较分析

Comparative Analysis of Different Coordinate Rotation Methods for Eddy Fluxes in Tazhong Station

坐标旋转是涡动协方差(EC)通量观测数据后处理当中必须进行的步骤,本文利用塔克拉玛干沙漠腹地塔中西面标校站自然沙丘上3m高度和塔中本站32m高度2009年4—10月湍流通量数据,对比分析了不同坐标旋转方法在塔中通量观测数据中的应用。结果表明,塔克拉玛干沙漠腹地塔中湍流各通量在旋转订正前后差别不显著,不订正造成的通量计算误差<1%。塔中32m和塔中西站3m通量计算误差,与两个站点的采集仪器架设高度差别较大有关。即使对于相对平坦的下垫面,也必须要进行倾斜校正,以修正地势、仪器振动、安装倾斜等产生的虚假信息。本研究对塔中涡动资料进行旋转时采用了二次坐标旋转方法。此结果为塔克拉玛干沙漠腹地EC通量观测的风速仪倾斜校正提供参考。

Coordinate rotation is an essential step for eddy covariance(EC)flux measurements in data post-processing.Based on the turbulence flux data in 3-m height in the west weather station of Tazhong and 32-m height in Tazhong weather station during April and October in 2009,we compared and analyzed the application of different coordinate rotation methods for eddy flux observation data in Tazhong.We found that the turbulent fluxes in Tazhong station which in the hinterland of the Taklamakan Desert do not have significant difference between before and after the rotation correction,and the error of flux calculation is less than 1%before the rotation correction.The error in flux calculation of 32-m height in Tazhong station and 3-m height tower in the west weather staion of Tazhong is related to the height of acquisition instrument erection between the two stations.Even for relatively flat underlying surfaces,tilt correction must be carried out to correct false information generated by terrain,instrument vibration,installation tilt,etc.In this study,we adopted the double coordinate rotation method to process EC flux data in Tazhong station.The results are useful for the tilt correction of anemometer in EC flux observations in the hinterland of the Taklimakan Desert.