饶平低温气候特征及预报系统建立

The Climatic Characteristics of Low Temperature in Raoping and Establishing of Forecast System

利用饶平气象站1956—2012年的气象观测资料以及国家气候中心提供的大气环流指数资料,分析饶平县低温气候特征,并分为低温寒冷型和低温阴雨型建立低温预报系统,结果发现:饶平县历年≤5℃低温日年平均日数4.0 d,主要出现在12月—次年2月,1月占48%,57年气候变化呈下降趋势,倾向为-0.089 d/年。饶平县历年低温阴雨年平均日数为5.9 d,近57年出现轻度低温阴雨年和重度低温阴雨年各占4成左右,中度低温阴雨年占2成,57年下降趋势不显著。对两种低温类型进行Mann-Kendall检验发现低温寒冷型突变点为1976年,下降倾向趋于明显为1987年开始;低温阴雨型突变点为1970年,下降倾向趋于明显为1999年开始。应用Morlet小波分析发现低温寒冷型存在5~7 a、10~12 a、准20 a周期;低温阴雨型存在5~6 a,10~12 a、准14 a、准20 a周期。使用主成份回归分析方法建立两种低温天气预报方程,低温寒冷型预报日最低气温预报拟合方程预测试验绝对残差平均为0.8℃;低温阴雨型预报低温阴雨年日数预报拟合方程预测试验绝对残差平均为2.1 d。基于Visual Basic语言开发饶平县低温天气预报系统,低温寒冷型预报次日最低温度并与寒冷预警信号关联,低温阴雨型预报次年低温阴雨日数并与低温阴雨年景强度关联,目前该系统已投入使用且效果良好。

Using the meteorological observation data from 1956 to 2012 in Raoping meteorological station and atmospheric circulation indices from Chinese National Climate Center, the climatic characteristics of low temperature in Raoping county were analyzed, and the forecast system were established for two low temperature types： the low temperature and cold weather （LTACW） , the low temperature and overcast weather （LTAOW）. The results show that： the annual average cold days（with temperature ≤5 ℃ ） in Raoping county are 4.0 d. The cold days appear in Dee to next Feb （ account for 48% in Jan） and the climate change of the annual average cold days in 57 years is a downward trend （ - 0. 089 d per year）. The annual average cold and overcast days in Raoping County are 5.9 d. In nearly 57 years, the mild and severe yearly prospect of LTAOW each account for about 40% and the moderate yearly prospect accounted for about 20%. The downward trend of LTAOW is insignificant in nearly 57 years. With analyzing two low temperature types by Mann- Kendall method, it is found that the LTACW type is changed suddenly in 1976 and the downward trend is significant since 1987. The LTAOW type is changed suddenly in 1970 and the downward trend is significant since 1999. The LTACW type has 5 ～ 7 a, 10 ～ 12 a and 20 a period oscillations and the LTAOW type has 5 ～6 a, 10 ～ 12 a, 14 a and 20 a period oscillations by wavelet analysis. Using the principle component regression method, the forecast equation of LTACW type is established to daily minimum tempera-ture forecast and the forecast equation of LTAOW type is established to annual cold and overcast days forecast. The average absolute residual value in the fitting equation of LTACW type is 0.8 ℃ in prediction test and it is 2.1 d in the fitting equation of LTAOW type. Based on Visual Basic, the cold weather forecast system is developed. The LTACW forecast system forecast the minimum temperature in next day and relate to the cold warning signal. The LTAOW forecast system forecast the cold and overcast days in next year and relate to the year strength of LTAOW. At present, the system has been put into use and the effect is good.