中国东部地区冬季低温季节内变化特征初步分析

A Preliminary Analysis of Intraseasonal Variation of Winter Low Temperature in Eastern China

本文基于中国气象数据网提供的1979~2013年共192站逐日最低温度观测资料及NCEP/NCAR、NCEP/DOE、JRA-55、ERA-Interim四套再分析资料,利用功率谱、Butterworth带通滤波等方法分析探讨了近35年来华东地区冬季12~2月多年平均低温阈值与低温日数及,并初步分析了季节内变化特征。结论如下:1) 华东地区阈值由北到南递增,高值区在浙江、江西、福建,低值区在山东、安徽、江苏,有南暖北冷的空间分布特征。JRA资料的低温阈值空间分布与观测资料更为接近,适用性更好。该地区低温日数和高低值区与阈值空间分布正好相反,有南低北高形势,NC1、NC2资料低温日数空间分布能重现观测结果。2) 华东地区低温事件有明显的季节内变化,其中1月低温日数最多,说明持续性低温事件最有可能出现在1月。华东地区冬季12~2月最低温度存在较强的10~20 d低频振荡周期。

In this paper, based on the daily minimum temperature observation data of 192 stations from 1979 to 2013 provided by China Meteorological Data Network and four sets of reanalysis data from NCEP/NCAR, NCEP/DOE, JRA-55 and ERA-Interim, the multi-year mean low-temperature threshold and the low-temperature days in winter from December to February in East China in recent 35 years were analyzed by means of power spectrum and Butterworth band pass filtering, and the characteristics of intraseasonal variation were preliminarily analyzed. The conclusions are as follows: 1) The threshold value increases from north to south in East China, with the high-value area in Zhejiang, Jiangxi and Fujian, and the low-value area in Shandong, Anhui and Jiangsu, showing the spatial distribution characteristics of warm in the south and cold in the north. The spatial distribution of low-temperature threshold of JRA data is closer to that of observation data and has better applicability. The spatial distribution of low-temperature days and high- and low-value areas in this region is the opposite of the threshold value, with a situation of low-temperature days in the south and high in the north. The spatial distribution of low-temperature days in NC1 and NC2 data can reproduce the observed results. 2) The low-temperature events in East China have obvious intraseasonal variation, and the low-temperature days in January are the highest, indicating that the sustained low-temperature events are most likely to occur in January. The minimum temperature in winter from December to February in East China has a strong low-frequency oscillation period of 10~20 d.