1960—2012年内蒙古降水集中度和降水集中期时空变化

利用内蒙古46个气象台站1960-2012年逐日降水数据,以表征降水年内分配非均匀特征的降水集中度(PCD)和降水集中期(PCP)指标,分析了内蒙古降水年内时间分配特征及变化趋势。结果表明:(1)近53 a内蒙古PCD平均值为0.70,呈显著减少趋势。PCP平均值为194.65°,呈不显著的提前趋势。(2)PCD高值区在阿拉善高原、锡林郭勒高原东部、呼伦贝尔高平原、大兴安岭以东地区,低值区在大兴安岭北部、乌兰察布高原、鄂尔多斯高原。全区PCP则以192°等值线为界,表现出西晚东早的空间分异格局。(3)PCD普遍呈下降趋势,以呼伦贝尔高平原、乌兰察布高原减小趋势最显著。PCP也以提前趋势为主,贺兰山、乌兰布和沙漠一线以东地区为主要的PCP提前区。(4)各站PCD与年降水量均为正相关,通过显著性检验的站点占到了60.8％。PCP与降水量的相关系数较小,显著相关的地区仅占到全区的34.7％。

Spatio-temporal Variations of Precipitation Concentration Degree and Precipitation Concentration Period in Inner Mongolia

Based on the daily precipitation data of the 46 meteorological stations in Inner Mongolia from 1960 to 2012, the inhomogeneity characteristics of annual precipitation and its trend during 1960-2012 in Inner Mongolia was analyzed by applying the Precipitation Concentration Degree (PCD) and Precipitation Concentration Period (PCP). The result showed that: (1)In recent 53 a, the mean PCD of Inner Mongolia was 0.7, with an apparent decreasing trend in Inner Mongolia; while the PCP in Inner Mongolia was 194.65°, showing an insignificant declined trend. (2) The area of high PCD value was mainly distributed in Alxa Plateau, the eastern part of XilinGol Plateau, Hulunbuir upland plain and the eastern areas of Greater Hinggan, while the low value centers lay in the northern areas of Greater Hinggan, Wulanchabu plateau and Ordos Plateau. Divided by the PCP contour line of 192°, the PCP in the whole area showed an obvious spatial difference, and the west is high while the east is low. (3) The PCD in Inner Mongolia showed a decreasing trend, especially in Hulunbuir upland plain and Ulanchap plateau. The PCP also showed a decreasing trend, indicating that the PCP appears earlier in the east of Helan Mountain and Ulan Buh Desert line.(4) PCD of all stations had a highly positive correlation with annual precipitation, and 60.8% of the stations passed statistically significant test, while PCP of all stations had low positive correlation with annual precipitation, merely with the area of 34.7% passed significant test.