1960—2013年洞庭湖区夏季高温的变化特征

Characteristics of the Variation of Summertime High Temperatures in the Area of Lake Dongting,Hunan Province from 1960 to 2013

根据洞庭湖区24个气象站1960—2013年夏季逐日气温资料,采用线性趋势分析及滑动平均等方法研究了洞庭湖区近54年夏季高温的变化特征。结果表明:洞庭湖区夏季高温日数和高温日平均最高气温分别以0.142 d/年、0.006℃/年的变化速率递增,尤其是进入21世纪后,高温日数和高温日平均最高气温变化都明显加快。洞庭湖区夏季高温日数多年平均为18 d,2013年最多为47d,1987年最少为8 d。高温日平均最高气温多年平均为36.1℃,2013年最高,为37.0℃,1965年最低,为35.5℃。洞庭湖区各单站的夏季平均高温日数和高温日平均最高气温变化并不一致,有9个站夏季平均高温日呈显著增加趋势,有12个站夏季高温日平均最高气温呈显著增强趋势,其余站点增加趋势并不显著。单站夏季平均高温日变化速率最大的是华容,以0.425 d/年的变化速率递增。单站夏季高温日平均最高气温变化速率最大的是安乡,以0.020℃/年的变化速率递增。洞庭湖区夏季高温日数和高温日平均最高气温均呈现出由北部的湖区向环洞庭湖山区呈辐射状递增的分布趋势。高温日数安化最多,为28 d,荆州、公安、石首、岳阳最少,均为12 d。高温日平均最高气温安化最高,为36.6℃,石首最低,为35.6℃。洞庭湖区夏季年最多高温日数出现在安乡和益阳,为55 d。极端最高气温出现在益阳,为43.6℃。

Based on the daily summertime temperature observations of 1960 to 2013 from 24 observation stations in the area of Lake Dongting, the variation characteristics of high temperatures are studied using the methods of linear trend and running mean. The results are shown as follows. The number of high - tempera- ture days （HTD） and daily mean maximum temperature in these days （MMT） are increasing by rates of 0. 142 d/year and 0. 006 ℃/year, respectively, and they both accelerate since the beginning of the 21st centu- ry. The multi -year mean is 18 d for HTD, with 2013 being the year with the largest number （47 d） and 1987 the year with the smallest number （8 d）. The multi -year mean is 36.1 ℃ for MMT, with 2013 being the year of the highest （37 % ） and 1965 the year of the lowest （35.5 ℃ ）. For individual stations in the ar- ea, the HTD does not change consistently with the MMT; the former shows an obviously increasing tendency in 9 stations while the latter presents such a trend in 12 stations, with no significant trends identified in the rest of the stations. For the rate of change, Huarong is the station with the maximum in HTD （0. 425 d/ year） and Anxiang is the station with the maximum in MMT （0. 020 ℃/year）. Both the HTD and MMT tend to be increasing in radial manner from the northern part of the lake to the mountainous areas around it, with Anhua at the top of HTD variation （28 d） and Jingzhou, Gong＇an, Shishou and Yueyang at the bottom （ all 12 d）, and Anhua, again, is the station that leads in the list of MMT change rate （36.6 ℃ ） and Sh- ishou is the one that most lags behind （35.6 ℃ ）. The yearly maximum HTD occurs in Anxiang and Yiyang （both 55 d） and extreme maximum temperature is with the station of Yiyang （43.6 ℃ ）