近30 a辽宁省夏季降水的时空变化特征分析

基于欧洲中期天气预报中心(ECMWF)提供的ERA5再分析资料,通过线性趋势分析、经验正交函数分解(EOF)等方法,研究了近30 a辽宁省夏季降水的时空变化特征,得出以下结论:辽宁省的年降水量具有雨热同期、分布不均的特点。1992—2021年1月平均年降水量最少,7月最多,7月年降水量可达164.1 mm。分季节来看,辽宁省夏季降水量占全年总降水量的60%,远高于其他季节。辽宁省夏季降水表现出显著的东多西少的特征,大值区位于辽宁省东部山地丘陵区,年降水量可达600 mm以上,小值区位于西部与内蒙古高原相连的山地丘陵区,部分区域年降水量不足300 mm。辽宁省近30 a区域平均夏季降水表现为减少的趋势,变化率为-31 mm/10 a。分区域来看,辽宁省东部地区夏季降水量表现为显著减少的趋势,西部地区次之。中东部地区夏季降水的减少趋势最为明显。EOF分解表明,辽宁省夏季降水距平场的第一模态表现为全域的一致性特征,其对应的时间系数有明显的年代际变化特征;第二模态表现为东西向的经向变化差异,表明降水在经向的对比加大,表现出辽宁省东西部地区对气候变化相反的响应性。

Based on the ERA5 reanalysis data provided by the European Centre for Medium-Range Weather Forecasts(ECMWF),through linear trend analysis,empirical orthogonal function decomposition(EOF)and other methods,the temporal and spatial variation characteristics of summer precipitation in Liaoning Province in the past 30 years were studied,and the following conclusions were drawn:(1)The annual precipitation in Liaoning Province has the characteristics of uneven distribution of rain and heat in the same period.In the past 30 years from 1992 to 2021,the average annual precipitation was the least in January and the largest in July,with an annual precipitation of 164.1 mm.In terms of seasons,the summer precipitation in Liaoning Province accounts for 60%of the total annual precipitation,much higher than other seasons.(2)The summer precipitation in Liaoning Province shows a significant feature of“more in the east and less in the west”.The large-value area is located in the mountainous and hilly area in the east of Liaoning Province,with an annual precipitation of more than 600 mm.The small-value area is located in the mountainous area connected to the Inner Mongolia Plateau in the west.In hilly areas,the annual precipitation in some areas is less than 300 mm.The average summer precipitation in Liaoning Province in the past 30 years showed a decreasing trend,with a change rate of-31mm/10a.In terms of sub-regions,the summer precipitation in the eastern part of Liaoning Province showed a significant decreasing trend,followed by the western part.The decreasing trend of summer precipitation in the central and eastern regions is the most obvious.(3)The EOF decomposition shows that the first mode of the summer precipitation anomaly field in Liaoning Province is consistent with the whole field,and its corresponding time coefficient has obvious interdecadal variation characteristics.The second mode shows the difference in meridional variation in the east-west direction,indicating that the contrast of precipitation in the meridian direction increases,showing the opposite responsiveness of the eastern and western regions of Liaoning Province to climate change.