不同阶曲线拟合扰动场对下平流层重力波气候特征影响研究

A study on the influence of disturbance fields from different-order curve fitting on climatic characteristics of gravity waves in the lower stratosphere

中文关键词:  曲线拟合  扰动场  重力波参数  气候特征

英文关键词:Curve fitting  Disturbance field  Gravity wave parameters  Climatic characteristics

中文摘要:

      重力波参数气候特征是确定大气模式中重力波参数化方案的重要条件之一，高垂直分辨率探空资料扰动场是获取重力波参数气候特征的基础数据；目前，获取扰动场的方法较多，但基于不同方法计算的扰动场对重力波参数气候特征影响的研究较少。基于2014—2017年山西太原气象台高垂直分辨率探空资料，利用2—4阶曲线拟合方法获取下平流层（17—24 km高度）温度扰动场、纬向风扰动场和经向风扰动场，经统计发现2阶与3阶曲线拟合方法的扰动场相似程度较高；在此选取相似度较高的2阶、3阶曲线拟合方法的扰动场分别计算大气重力波参数，并对大气重力波参数间的气候差异特征进行研究。结果表明：（1）不同阶曲线拟合方法扰动场的变化振幅及随高度变化趋势存在差异，且扰动场间的相关较弱；（2）2阶、3阶曲线拟合方法扰动场得到的重力波参数大小、年内变化趋势及在不同区间范围内占有率均存在差异，且相关较弱；（3）1—12月，相对3阶曲线拟合方法的扰动场，基于2阶曲线拟合方法的扰动场得到的重力波群速、水平波长、垂直波长、周期、固有相速均较大，而重力波能量上传百分比在某些月份较大。因此，不同阶曲线拟合方法扰动场间存在差异，会导致计算得到的大气重力波参数气候特征存在差异，最终对研制大气模式中的大气重力波参数化方案产生影响。

英文摘要:

      The climatic characteristics of gravity wave parameters is an important part of the parameterization of gravity waves in the development of global atmospheric model. High vertical resolution sounding data of disturbance fields are the basic data that can be used to obtain climate characteristics of gravity wave parameters. At present, there are many methods to obtain the disturbance field, but there are few studies on the influence of the disturbance field on the calculated climate characteristics of the gravity wave parameters. Based on the high vertical resolution sounding data collected at Taiyuan Meteorological Observatory in Shanxi from 2014 to 2017, the 2—4 order curve fitting methods are used to obtain vertical profiles of temperature disturbance field, zonal wind disturbance field, and meridional wind disturbance field in the lower stratosphere (17—24 km). Statistical analysis shows that the disturbance fields obtained by the second- and third-order curve fitting methods are more similar. Therefore, the second- and third-order curve fitting methods are selected to calculate the atmospheric gravity wave parameters, and the characteristics of differences in the atmospheric gravity wave parameters between results of the two methods are statistically analyzed. The results are as follows. (1) Disturbance fields obtained from different-order curve fitting methods show different amplitudes, different trends with height, and weak correlation; (2) gravity wave parameters obtained by the second-order and third-order curves fitted disturbance fields are different in the size, the annual variation trend and occupancy rate within different intervals, and the correlation is weak; (3) from January to December, compared with the third-order curve fitted disturbance field, the gravity wave group velocity, horizontal wavelength, vertical wavelength, period, and intrinsic phase velocity obtained by the disturbance field from the second-order curve fitting method are larger, and the fraction of upward propagating energy is also larger in some months. Therefore, it is concluded that the disturbance fields from different-order curve fitting methods are different, which can lead to differences in the climatic characteristics of the calculated atmospheric gravity wave parameters and eventually influence the effect of the parameterization scheme in the atmospheric model.