西沙群岛和涠洲岛气候变化特征及其与近岸陆地的对比

Climate Change Characteristics of the Xisha Islands and Weizhou Island in China and the Comparison with the Coastal Land

采用1959―2014年中国西沙站和涠洲岛站及其临近陆地台站的基本气象观测资料,分析了2个海岛的气候变化特征及其与近岸陆地的差异。结果表明:1)近56年西沙和涠洲岛及近岸陆地气温变化均呈上升趋势,西沙增暖速率(0.19℃/10 a)大于涠洲岛(0.104℃/10 a)。显著的差异出现在近10年,西沙持续增暖(0.38℃/10 a),而涠洲岛气温却呈下降趋势(-0.48℃/10 a)。从季节变化上,2个海岛都有春季越来越暖、冬季越来越冷的趋势。与周围陆地的气温相比,2个海岛的气温均高于近海陆地,但增温速率却小于近岸陆地。2)分析近56年降水量的变化,发现海岛降水量、降水强度和降水天数均小于陆地。受冬、夏季风转换的控制,海岛及近岸陆地有旱季、雨季的划分,且近半个世纪以来降水量波动大、变化趋势不显著,但伴随降水天数的减少,降水强度呈显著增长趋势。对比2个海岛近10年的降水变化特征,发现西沙站的旱季有越来越旱的趋势,涠洲岛及近岸陆地无论旱季、雨季降水量都有增加的趋势,表现为湿润化的趋势。

In this paper, the features of climate change and the difference between the islands and the coastal land are analyzed based on the basic meteorological data from the Xisha station and Weizhou Island station and their adjacent land stations from 1959 to 2014. The results show that： 1） in recent 56 years, the temperature changes in the Xisha Islands and Weizhou Island have shown an upward trend, the heating rate in the Xisha（0.19℃/10 a） is greater than that in Weizhou Island（0.104℃/10 a）. Significant differences occurred in the last 10 years, the Xisha continued warming significantly（0.38 ℃/10 a）, while the temperature of Weizhou Island had a downward trend（-0.48℃/10 a）. As for the seasonal changes in the analysis, the spring of the islands was getting warmer while the winter getting colder. As compared with the surrounding land, the temperature of the islands was higher than that of the coastal land, but the warming rate less than that of the coastal land. 2） From analyzing the change of precipitation in recent 56 years, it is found that the precipitation, precipitation intensity and precipitation days of the islands were less than those of the coastal land. Controlled by the winter and summer monsoon conversion,Weizhou Island and the Xisha Islands showed a distinct dry season and a rainy season. Precipitation fluctuated greatly and its trend was insignificant in the last half century. With the decrease of precipitation days, precipitation intensity showed a significant growth trend. Contrasting the precipitation variation characteristics of the islands in nearly 10 years, we found that the Xisha station trended to be drier and drier in the dry season, and the precipitation in Weizhou Island and coastal land was increasing in both dry season and rainy season. 3） The average annual precipitation, the average precipitation in the rainy season and the average precipitation in the dry season in the islands were smaller than those in coastal land, but situation in the Xisha was opposite in November,December and January, that in Weizhou Island was opposite in January, July and August. The reason for this difference is that the land area in the Xisha is smaller and is more affected by oceanic air mass. Under the influence of South Asian monsoon, the seasonal characteristics were significant, it was humid and rainy in summer while dry and less rain in winter in Weizhou Island. The annual average precipitation and rainy season precipitation both in the Xisha and in coastal land were higher than those in Weizhou Island and its near shore area.During the dry season, the precipitation of the Xisha and the near shore area was lower than that of Weizhou Island and its near shore.