曲线拟合扰动场对提取的大气重力波参数影响

Effects of curve fitting method for perturbation fields in atmospheric gravity wave parameters estimation

重力波是大气中最基本的动力过程,估算大气重力波参数是大气动力学理论研究的重要内容之一.本文利用一次东亚副热带高空急流演变过程的高分辨率数值模拟结果,采用Morlet小波分析方法,针对常用的二阶、三阶和四阶曲线拟合得到的扰动场进行分析;并通过建立数学模型,分析含不同强弱背景场信号时的扰动场对大气重力波参数的影响,结果表明:(1)曲线拟合方法得到的扰动场中含较强背景场信号;(2)扰动场中背景场信号强弱对大气重力波参数有很大的影响;(3)要想提取准确的大气重力波参数,必须确保多种扰动场中同时含很弱或不含背景场信号,因此在提取大气重力波参数时,采用曲线拟合方法获取扰动场存在缺陷,需要设计更合理的背景场获取方法.

The gravity wave is the fundamental dynamic process in the atmosphere,and one of the important theoretical studies of atmosphere dynamics is to estimate the gravity wave parameters.Based on the numerical simulation results for the case of subtropical upper level jet over east Asia in the paper,Using Morlet wavelet transform technique to analyze perturbation field from curve fitting method; And establishing a mathematical model to research atmospheric gravity wave parameters（ AGWPs） results obtained by the perturbation fields,which include the background field signal with different intensity. The results showed that：（ 1） The perturbation fields from the curve fitting method contain the intensity background field signal;（ 2） The perturbation fields have a great impact on the results of AGWPs,when it include the background fields signal with different intensity.（ 3） In order to obtain the more accurate AGWPs,Then the perturbation fields must contain week or little background field signals. Therefore,it is necessary to develop a suitable method in obtaining the perturbation fields of the wind and temperature profiles in AGWPs estimation.