1961—2010年云南干湿气候变化

Dry-Wet Climate Change in Yunnan During 1961-2010

利用15个站点1961—2010年日照时数、降水量和平均温度等气候资料,计算云南5个区域各季节相对湿润度指数,分析云南干湿气候变化特征。结果表明,相对湿润度指数可定量、准确地表达云南各区域自然气候干湿程度,能客观反映云南干湿气候的波动变化和区域性差别。20世纪90年代中期以来,云南干季、雨季潜在蒸散量呈增大变化趋势,同期降水量有减小的趋势变化,从而在气候变暖背景下引发云南气候的干旱化趋势。干季各地相对湿润度指数年际波动变化大,年代际差异明显;雨季各地干湿状况年际波动相对较小,且呈现明显的周期性波动变化趋势。云南5个区域的干湿气候变化既有一致性也有差异性:滇中和滇西南比较一致,滇西北与滇东南差异明显,滇西北与滇东北雨季差异突出、干季较为相似。

Based on the climate data of sunshine duration, precipitation, average temperature, and so on from 15 representative meteorological stations in Yunnan Province from 1961 to 2010, the natural dry wet climate change and its regional differences in different seasons are analyzed. The results show that the relative moisture index can quantitatively and accurately express the natural climate wet dry status, and objectively reflect the variation over the years and the regional differences for dry wet climate in Yunnan. In the respect of variation trends, potential evapotranspiration was increasing and precipitation was decreasing during both dry and wet seasons since the mid 1990s, which led to obvious aridification trend jointly in Yunnan under the background of climate warming. Meanwhile, the relative moisture index of Yunnan had the bigger inter annual fluctuations in dry season （compared to rainy season） and obvious inter decadal differences. The wet dry climate status of rainy season showed evident periodic variation trends in all regions. Flood drought climate changes of five regions in Yunnan had both consistencies and differences. Especially, the central Yunnan was obviously consistent with the southwestern part, while the northwest was distinctly different from the southeast. The northeast had distinction during rainy season but claimed similarity in dry season with northwest Yunnan.