1960-2017年渭河流域极端气温变化及其对区域增暖的响应

基于逐日最高和最低气温,计算1960-2017年渭河流域16项极端气温指数,发现近58 a 渭河流域极端冷指数（冰冻日数、霜冻日数、冷夜日数、冷昼日数和冷持续指数）呈下降趋势,极端暖指数（夏日日数、热夜日数、暖昼日数、暖夜日数、作物生长期和热持续指数）呈上升趋势,特别是20世纪80年代后上升速率明显加快。流域半干旱区对气候变暖的响应更敏感,主要体现在白天温度增高以及冰冻和霜冻日数减少,而半湿润区主要为夜间增暖。相比1960-2003年,2004-2017年流域平均温度升高1.75℃,暖夜/暖昼日数增加10.99/6.79 d,而霜冻/冷夜日数减少8.71/2.35 d。分析发现地形条件是影响流域极端气温空间差异的重要因素。在流域半干旱区,冷夜和冷昼日数的快速减少,有利于农作物的生长。而在相对湿度较大的半湿润区,随着夏季连续高温天气增多,高温热浪事件的危害更大。

Variations of Extreme Temperature and Its Response on Regional Warming in the Weihe River Basin During 1960-2017

Extreme temperature is an important indicator of climate change and an important reference for rational arrangement of agricultural production. Based on the daily maximum and minimum temperature of the Weihe River Basin during 1960-2017, and 16 indices of extreme temperature were computed to reveal the trend of extreme temperature in weihe river basin and its response to global warming. This article analyzed the variation trends of extreme temperature and its response on regional warming in different climate zones of basin. The results are as follows: The extreme cold index (ice days, frost days, cool nights, cool days and cold speel duration index) showed a downward trend of the Weihe River Basin during 1960-2017, while the extreme hot index (summer days, tropical nights, warm days, warm nights and warm speel duration index) had an upward trend, especially after the 1980s, the upward trend accelerated. The response of the extreme temperature index on regional warming in semi-arid regions was more sensitive and the response was mainly reflected in the increase of daytime temperature and the significant reduction of freezing and frosting days, while in semi-humid regions, the warming was obvious at night and in the extension of crop growth. Comparing with 1960-2004, the average temperature of basin increased by 1.62℃ during 2005-2017, warm nights and summer days increased by 8.33 and 7.28 days, and ice and frost days decreased by 8.68 and 2.58 days. Topographic condition was the important influencing factor of spatial variations of extreme temperature in this basin. In semi-arid regions of basin, the rapid reduction of ice and frost days are conducive to the growth of crops. However, in the semi-humid area with relatively high humidity, high-temperature heat wave events are more harmful with the increase of continuous hot weather in summer.