青海高原1960—2019年冬半年降水变化特征及重心迁移研究

Research on the characteristics of precipitation change and center of gravity migration in winter half year of 1960-2019 in the Qinghai Plateau

冬半年降水对农业、交通、生态安全等方面都有很大影响。青海高原是我国冬半年强降水量、降水日数最多的地方之一。利用重心模型来分析青海高原42个气象站1961—2019年不同等级冬半年降水的空间分布和变化迁移,旨在揭示青海高原多年的冬半年降水的时空分配格局。结果显示:(1)空间上青海高原冬半年平均降水量呈现出由西北向东南递增的趋势,且东部地区冬半年降水量呈现明显的下降趋势;时间上整体呈增加趋势,年代周期内呈现“少-多-少-多-少-多”的趋势。(2)不同等级冬半年降水量的气候倾向率的空间分布整体呈现南高北低,西高东低的趋势。青海高原冬半年降水量的变化整体以大量级的增加为主,尤其在中南部地区,增加速率更大。(3)青海省的冬半年降水量重心的纬度和经度均呈现降低的趋势,重心点坐标呈现向西南方向逐渐移动的趋势。青海高原冬半年降水量重心的空间位置集中分布于兴海县附近,最北边可到达共和县,最南边可迁移至玛沁县,青海高原多年降水重心的标准差椭圆的方位角度数为55.8°,冬半年降水量重心主要分布于东北至西南的方向上。(4)青海高原各等级冬半年降水量的经、纬度时间变化上均呈现下降趋势,且经度的变化速率较纬度的高。各降水量级的标准差椭圆的方位角大小相差十几度,但均为东北至西南方向分布,且主要分布在兴海县附近,轴长和椭圆圆心坐标存在较大差异。冬半年降水重心量级越小离散性越小,且平均降水量的重心离散程度和分布也是小量级降水量的贡献较大。可以利用冬半年降水重心的南北移动方向来判断青海高原大量级降雪范围的变化。

Winter precipitation has a great impact on agriculture,transportation,ecological security,etc.The Qinghai Plateau is one of the places with the most heavy rainfall and the most rainfall days in winter half year in China.In this paper,the center of gravity model is used to analyze the spatial distribution and change migration of winter half year precipitation of different grades in 42 meteorological stations in Qinghai Plateau from 1961 to 2019.Aiming to reveal the spatiotemporal distribution pattern of precipitation in winter half year over the Qinghai Plateau for many years.The results show that:1)Spatially,the average precipitation in winter half year in the Qinghai Plateau shows an increasing trend from northwest to southeast.In addition,the precipitation in winter half year in the eastern region showed a significant downward trend.In terms of time,the overall trend is increasing,and the trend of"less-more-less-more-less-more"appears in the decadal cycle.2)The spatial distribution of the climatic inclination rates of different grades of winter half year precipitation showed a trend of high in the south and low in the north,high in the west and low in the east.The change of winter half year precipitation in the Qinghai Plateau is dominated by the increase of a large number of levels,especially in the central and southern regions,with a greater increase rate.3)The latitude and longitude of the winter half year precipitation center in Qinghai Province showed a decreasing trend,and the coordinates of the center of gravity showed a trend of gradually moving to the southwest.The spatial location of the center of gravity of winter half year precipitation in the Qinghai Plateau is concentrated near Xinghai County,the northernmost can reach Gonghe County,and the southernmost can migrate to Maqin County.The center of gravity of winter half year precipitation is mainly distributed in the direction from northeast to southwest.The azimuth angle of the standard deviation ellipse of the multi-year precipitation gravity center of the Qinghai Plateau is 55.8°,and the gravity center of winter half year precipitation is mainly distributed in the direction from northeast to southwest.4)The latitude and longitude temporal changes of winter half year precipitation of all grades in the Qinghai Plateau show a downward trend,and the change rate of longitude is higher than that of latitude.The azimuth angles of the standard deviation ellipses of each precipitation level differ by more than ten degrees,but they are distributed in the northeast to southwest direction,and are mainly distributed in the vicinity of Xinghai County.The smaller the magnitude of the gravity center of winter half year precipitation,the smaller the dispersion,and the dispersion degree and distribution of the center of gravity of the average precipitation is also a larger contribution to the small-scale precipitation.The north-south moving direction of the precipitation center in the winter half year can be used to judge the change of the range of large-scale snowfall on the Qinghai Plateau.