摘要
运用多种方法,对中国西南地区110个气象站1961—2009年日照时数变化的研究发现,该区年均日照时数为1 894 h,日照时数的较大值主要分布存海拔较高的西藏高原、横断山区和云南高原,而贵州高原和四川盆地日照时数相对较少.研究区年和季节日照时数在1990年之前降低,此后明显增加.日照时数降低的台站主要分布在低海拔区,特别是四川盆地和贵州高原,位于高海拔区的大多数台站降低幅度较小或呈增加趋势.风速是影响研究区日照时数变化的主要原冈,1969—2009年除秋季外风速与日照时数变化呈显著正相关,而且展现出相同的变化趋势.1969—2000年日照时数降低幅度明显大于2001—2009年,两个时段日照时数变化幅度的空间分布格局与同时段风速变化相似.除春、秋季外,1969—2009年风速小于1.5 m/s的台站日照时数的降低幅度明显高于风速大于1.5 m/s的台站,而且年和季节日照时数表现降低趋势的台站百分率也是前者大于后者.湿度是影响日照时数变化的又一因素,1961—2009年湿度与日照时数变化呈明显反向趋势,而且年和季节日照时数变化都与湿度变化显著负相关.此外,地表接收的太阳辐射通量、云覆盖面积、云中含水量和降水也对日照时数变化有显著影响,特别是引起了1970年和1990年前后日照时数的明显变化.
With various methods, the temporal and spatial vaiation of sunshine hours over southwestern China during 1961-2009 were analyzed based on data collected from 110 standard meteorological stations. The results showed that annual mean sunshine hours was 1 894 h, and the higher values were distributed in the Tibetan plateau, Hengduan mountains and Yunnan plateau, whereas the lower values were located at Guizhou plateau and Sichuan basin. Annual and seasonal sunshine hours decreased before 1990 and increased after that. Spatially, statistically significant decreases of sunshine hours mainly occurred in lower altitude regions, especially in the Sichuan basin and Guizhou plateau, whiles there were increases or smaller decreases at higher altitudes regions. Wind speed was the main reason for the changed sunshine hours. It showed a closely temporal and spatial correlation between wind speed and sunshine hours in 1969-2009, and the decreasing magnitudes was larger in 1969-2000 than in 2001-2009 with the same spatial pattern~ and a larger decreasing trend displayed a declining trend in non-windy days than in windy days with the exception of spring and autumn. The relative humidity was the secondary influencing factor for the changed sunshine hours, and this could be reflected by a significantnegative correlation and a reverse trend between the two variables. In addition, the surface downward solar radiation flux, cloud cover, cloud water content and precipitation also made some contribution to a rise of sunshine hours during 1991-2009, which especially caused an obvious variation in the 1970s and 1990s.
出处
《兰州大学学报（自然科学版）》
CAS
CSCD
北大核心
2012年第5期52-60,共9页
Journal of Lanzhou University(Natural Sciences)
基金
国家自然科学基金项目(11J0930003
91025002
40725001
30970492)
关键词
气候变化
日照时数
西南地区
climate change
sunshine hours
southwestern China
