陕北地区1960—2013年极端气温指数

Extreme Temperatures Indexes in North Shaanxi during 1960-2013

以陕北地区1960—2013年的逐日气温数据为基础,运用Mann-Kendall非参数检验法,分析了该区极端气温指数及其变化趋势。结果表明:(1)陕北地区年平均气温、最高和最低气温分别以0.27、0.24、0.28℃/10a的速率显著增加(P<0.05),各站点气温指标均上升,且冬季变暖幅度最大,春季次之。(2)最低气温极高值、暖夜、暖日分别以0.054℃/10a、1.83d/10a、1.4d/10a显著增大;年日最高气温极高值与生长日长度增幅分别为0.092℃/10a、2.4d/10a;暖日、暖夜各季节亦显著上升;气温日较差以-0.036℃/10a的速率减小。除气温日较差外,其余指数均有50%以上的站点呈上升趋势。(3)最高气温极低值增幅为0.217℃/10a;最低气温极低值、冷日减幅分别为-0.015℃/10a、-0.48d/10a;冷夜以-0.98d/10a的速率显著减小;霜日及冰日分别以2.2/10a、2.4d/10a的速率显著减小。除最低气温极低值及最高气温极低值外,其余指数均有100%的站点呈下降趋势。4)暖指数的增大幅度大于冷指数的减小幅度,夜指数的减小幅度大于昼指数增大幅度。极端气温的两极化分布趋势导致研究区域高温、旱灾及冰冻等灾害的频发。

Based on daily temperatures data in 6 weather stations, this study applied Mann-Kendall nonpara- metric tests to analyze the variation of extreme temperatures indexes from 1960 to 2013 in north Shaanxi. The results showed that： （1）Annual mean, maximum and minimum temperatures were significant rising （P〈0.05） with rates of 0.27℃/10a, 0.24 ℃/10a, 0. 28 ℃/10a respectively in north Shaanxi during 1960-- 2013, and winter temperatures warms up biggest and spring next. （2） The yearly maximum value of daily minimum temperature, warm night, and warm day were significantly increased （ P%0.05 ） with rates of 0. 054 ℃/10a, 1.83 d/10a, 1.4 d/10a respectively; the yearly maximum value of daily maximum tempera- ture increased at a rate of 0.0 92 ℃/10a; warm night, and warm day showed a significant increasing trend in each season; the daily temperature range decreased at a rate of 0. 036 ℃/10a; the length of growth increased at a rate of 2.4 d/10a. And 50% of stations increased in each indexes, except the length of growth. （3） The yearly minimum value of daily maximum temperature weak increased and the growth rate was 0. 217 ℃/10a; the yearly minimum value of daily minimum temperature decreased at a rate of 0. 015 ℃/ 10a; cold day performance a significant decreasing trend （P〈0. 05）, the change amplitude of 0. 48 d/10a; cold day were decreased in each season, except the summer; cold night significant decreased （P%0.05）at a trend of 0. 98 d/10a; frost day and ice day reduced at rates of 2.2/10a, 2.4 d/10a respectively. And 100% of stations increased in each indexes, except the yearly minimum value of daily maximum temperature, the yearly minimum value of daily minimum temperature. （4） Warm indexes increased more than coldness indexes decreasing, and night indexes were greater decreased than the day indexes increasing. Polarization distribution trend of extreme temperature result in frequently high temperature, drought, and freezing disasters in the study area.