黑龙江省夏季低温指数变化特征分析

Characteristic of the Lowest Temperature Index Changes in Summer of Heilongjiang Province

为了解近44年来黑龙江省夏季低温指数的分布规律和变化趋势。利用1971-2014年黑龙江省80个气象台站夏季日最低气温和平均气温观测资料,结合低温指数模型,通过趋势变化、小波分析和Mann-Kendall检测等方法,分析黑龙江省夏季低温指数的变化特征。结果表明:黑龙江省夏季平均低温指数呈减少趋势,夏季低温指数在20世纪80、90年代和21世纪初变化不明显,而2010s以来明显减少,夏季平均低温指数较春季小。气温从1980s升温以来,低温指数明显减少,夏季低温指数自1970s中期以来明显减少,低温指数序列突变开始于1983年前后,夏季低温指数变化与气温呈负相关。夏季低温指数存在18～32 a,6～14 a和4～8 a三个尺度的周期变化,其中18～32 a尺度非常稳定且具全域性,在1980s中期以前6～14 a尺度较为稳定,在1980s中期以后4～8 a尺度较为稳定,7～12 a尺度年周期变化最明显但有局域性(1980s中期以前),24～31 a尺度能量虽弱且具有全域性。夏季低温指数有26、8、和5 a的主周期,其中第一主周期为8 a,平均周期为5.5 a;第二主周期为26 a,平均周期为14.5 a。

The paper aims to understand the distribution rule and trend of the lowest temperature index in summer of Heilongjiang Province over the past 44 years.The authors used the lowest temperature index model,trend of change,the wavelet analysis and Mann-Kendall test to analyze the variation characteristics of the lowest temperature index in summer,based on the daily data of the lowest temperature,average temperature from 80 meteorological stations in Heilongjiang from 1971 to 2014.The results showed that,it was a downtrend to the lowest temperature index in summer in Heilongjiang Province,the lowest temperature index changed little in 1980s,1990s and 2000s,and had decreased significantly since 2010s.In summer,the mean value of the lowest temperature index was smaller than that in spring.The lowest temperature index had obviously decreased as the temperature rose from 1980s,and the lowest temperature index in summer had decreased significantly since the mid-1970s,the sequence mutation of the lowest temperature index in summer began from 1983,the change of lowest temperature index in summer was negatively correlated with temperature.There were 3 periodic changes of scales in the lowest temperature of summer,which were 18-32 years,6-14 years and 4-8 years.The scales of 18-32 years was very stable in the whole duration.The scale of 6-14 years was more stable in the former of 1980s.The scale of 4-8 years was more stable in the later of 1980s.The scale of 7-12 years was the most obvious but locality before the middle of 1980s.The scale of 24-31 years was less energy and full domain.The main cycle of the lowest temperature index of summer had 26 years,8 years and 5 years,the scales of 8 years was the first main cycle,and the average cycle was about 5.5 years,the scales of 26 years was the second main cycle and the average cycle was about 14.5 years.