连山县近50年低温、霜冻的变化特征及防御措施

Fifty-year Variation Characteristics of Low Temperature and Frost in Lianshan County and Measures Against Them

利用1962—2010年广东清远连山气象站低温、霜冻资料,通过数理统计、Mann-Kendall和Morlet小波分析、滑动t检验、Yamamoto等方法,对连山低温、霜冻日数的年、月变化以及初、终日进行分析。结果表明:连山年平均低温、霜冻日数分别为43.6和12.3 d。低温、霜冻日数每10年减少2.4和1.7 d左右;总体上低温、霜冻都呈现减少趋势。低温、霜冻主要集中在12月至翌年2月。低温日数在1月出现最多,平均为15.5 d;霜冻,出现最多月份为12月,平均为5.2 d。初霜冻总体呈现推迟趋势,初霜冻日主要出现在11月下旬和12月上旬;终霜冻总体呈现提早趋势,终霜冻日主要出现在2、3月上旬和1月下旬。无霜期呈显著的延长趋势。低温,霜冻,存在多重时间周期尺度上的嵌套结构现象,低温、霜冻没有发生突变。

Using the data of low temperature and frost from a meteorological station in Lianshan,Qingyuan,Guangdong province from 1962 to 2010,this work analyzes the annual and monthly variations of the numbers of low-temperature and frost days and their relative first and last day of occurrence in the course of a year employing the methods of mathematical statistics,Mann-Kendall test,Morlet wavelet analysis,moving t-test and Yamamoto approach.The result is shown as follows.In Lianshan,annual mean numbers of low-temperature and frost days are 43.6 and 12.3 d respectively,which are decreasing by about 2.4 and 1.7 d respectively every 10 years.Generally,there is a trend of decreasing incidence of low temperature and frost.They are mostly seen from December to the following February.For low temperature,its number of days is the most in January,15.5 d on average.For frost,it is the most in December,5.2 d on average.The first day of frost appearance tends to delay generally,mainly in late November and early December while the last day of frost appearance tends to advance,mainly in early February and early March and late January.Frost-free periods tend to prolong significantly.Free of any abrupt change,low temperature and frost are structurally nested with multiple scales of temporal period.