1949-2000年山西高原低温冷害特征及小波分析

低温冷害在山西高原四季均可发生，给工农业生产、交通运输和人们的生活带来很大影响，甚至造成严重损失。为了科学有效地预防和减轻此类灾害，需要深入研究其特征和规律，通过对山西1949-2000年资料的搜集、整理和数学分析，对该地区低温冷害的等级、阶段、周期及成因进行了研究。结果表明，52年来山西共发生低温冷害374次，轻度占16.8%；中度占61.0%；重度占22.2%。灾害变化可分为4个阶段，1949-1956年为第1阶段，1957-1975年为第2阶段，1976-1995年为第3阶段，1996-2000年为第4阶段。第1、3阶段距平值主要为正值，灾害频次较高，以中、重度灾害为主。第2、4阶段距平值主要为负值，灾害发生频次低，以轻、中度灾害为主。小波分析表明，灾害存在为2~3年、5~8年和15~20年的周期。降霜、降雪或寒流引起的气温骤降至0℃以下是造成山西低温冷害的主要原因，气温变化幅度为-25.6℃~-0.8℃。

The Characteristics of Frost, Snow and Low-temperature Disasters and Wavelet Analysis of Shanxi Plateau from 1949 to 2000

Frost, snow and low-temperature disasters may occur throughout the year in Shanxi plateau, they have significant impacts on industrial and agricultural production, transportation and people’s lives, and even cause serious losses. In order to prevent and mitigate such disasters, it was needed to in-depth study their characteristics and regularity. Through collecting, reorganizing and analyzing the data about Shanxi from 1949 to 2000, the article studies the grade series, stage changes, different grades’ periodicity and reason of the frost, snow and low-temperature disasters. The statistical results showed that the disasters had 374 times, they might be divided into mild，moderate and severe disaster, and their occurrence probabilities were 16.8%, 61.0% and 22.2%. The disasters could be divided into 4 stages. The first stage was from 1949 to 1956, the second stage was from 1957 to 1975, the third stage was from 1976 to 1995 and the forth stage was from 1996 to 2000. The first and third stages were that the disasters happen frequently, and most of them were moderate and severe disasters. The second and forth stages were that the disasters happen occasionally, and most of them were mild and moderate disasters. According to wavelets analysis, it was known that there were mainly periods of 2-3 a, 5-8 a and 15-20 a. The main reason causing the disasters was that the temperature suddenly decreased below 0℃, the temperature changes ranges were -25.6℃--0.8℃.