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最近几年华南地区干旱频发,为探讨该地区的干旱趋势,用标准化降水蒸散指数(SPEI)和1961-2010年华南地区具有代表性的50个站点的月降水及月平均气温资料,分析了该地区近50年来的干旱趋势、干旱空间分布、极端干旱事件发生频次和干旱持续时间。结果表明,华南地区普遍存在干旱事实,最近10年是干旱最严重的10年,Mann-Kendall检验表明该地区平均SPEI指数从1998年开始突变;干旱化最严重的区域是海南岛、广西南部和西部地区,广东的干旱化趋势最轻。20世纪70年代干旱和极端干旱事件较少,其后明显增多,干旱持续时间也有所延长。由于该地区降水呈现弱增加趋势而温度升高显著,因此推测温度升高导致蒸散增加可能是华南地区干旱化的主要原因。另外,降水频次的减少和集中也是导致近来极端干旱事件增多的原因之一。SPEI指数较好地体现了气候变暖导致的干旱化趋势。
In recent years, the drought in south China has been frequent. In order to discuss the trend of drought in this area, the monthly precipitation and monthly mean temperature data of 50 stations in South China from 1961 to 2010 were analyzed by using standardized precipitation evapotranspiration index (SPEI) Drought trends in the region over the past 50 years, spatial distribution of aridity, frequency of extreme drought events and duration of drought. The results show that there is a widespread drought in South China and the worst 10 years of drought in the last 10 years. The test by Mann-Kendall shows that the average SPEI index of this area has mutated since 1998; the most arid regions are Hainan Island, southern Guangxi and In western China, the drought in Guangdong is the lightest. In the 1970s there were fewer droughts and extreme droughts, followed by a marked increase in the duration of droughts. Because of the weak increasing trend of precipitation in this area, the temperature increase is significant. Therefore, it is speculated that the increase of evapotranspiration caused by the increase of temperature may be the main reason of drought in southern China. In addition, the reduction and concentration of precipitation have also contributed to the recent increase in extreme droughts. SPEI index better reflects the trend of drought caused by climate warming.