Abstract:

The heterogeneity of precipitation in space and time can easily lead to the formation of drought and flood disasters. Under the background of global warming, there are significant regional differences in spatio-temporal distribution patterns of precipitation. It is of great significance for food security, flood control and drought relief to explore the heterogeneity characteristics of regional precipitation. Based on the daily precipitation observation data of Heilongjiang Province in summer from 1951 to 2020, the common calculation methods of precipitation concentration period (PCP) and precipitation concentration degree (PCD) are contrastively screened, firstly. Then, combined with correlation analysis, trend analysis and wavelet analysis, the characteristics of summer precipitation non-uniformity and its influencing factors are explored in Heilongjiang Province. The results show that the Heilongjiang summer PCP is earlier in the southwest and later in the northeast, and the earliest PCP is in the hinterland of the Songnen Plain (July 6 to 20), the latest PCP is in the hinterland of the Sanjiang Plain (August 10 to 25). The summer PCD is larger in the west and smaller in the north-central, northwest and southeast edge, the smallest PCD is in the transition zone between the Lesser Khingan Mountains and the Sanjiang Plain, and the largest PCD is in the hinterland of the Songnen Plain. When the summer PCP is early, the summer PCD tends to be large, which indicates that the summer precipitation in the areas with early heavy precipitation tends to be more in the early stage and less in the late stage. The inter-annual scale oscillation with a period of 2.0-4.0 a of summer PCP and PCD in Heilongjiang Province is obvious, and there is non-significant change trend on the whole. The summer PCP and PCD are significantly affected by the atmospheric circulation and sea temperature in the early period and the same period. On the whole, the summer PCP is significantly positively correlated with the North American polar vortex area index in May, while it is significantly negatively correlated with the western Pacific 850 hPa trade wind index in May and the Scandinavia teleconnection pattern index in August. The summer PCD is significantly positively correlated with the central Pacific 850 hPa trade wind index in summer, while it is significantly negatively with the North African-North Atlantic-North American subtropical high ridge position index in June and the eastern Pacific ENSO index in July, but the significant correlation regions for different climate indexes were different.

Key words: summer precipitation, heterogenity, PCP, PCD, influencing factors

摘要：

降水时空分布的非均匀性，易导致旱涝灾害的形成。全球变暖背景下降水时空分布格局变化有显著的区域性差异，探讨区域降水的非均匀性特征，对粮食安全、防汛抗旱有重要意义。本文基于1951—2020年黑龙江夏季逐日降水量观测资料，对比筛选常用的降水集中期和集中度计算方法，结合相关分析、趋势分析、小波分析等方法，探究黑龙江夏季降水非均匀性特征及其影响因素。结果表明：气候态上，黑龙江夏季降水集中期西南部偏早、东北部偏晚，最早在松嫩平原腹地（7月6—20日），最晚在三江平原腹地（8月10—25日）；夏季降水集中度西部大而中北部、西北部和东南缘小，最小在小兴安岭与三江平原过渡地带，最大在松嫩平原腹地。集中期偏早，集中度易偏大，在强降水早发区夏季降水易前期偏多、后期偏少。黑龙江夏季降水集中期和集中度年际尺度振荡明显，以2.0~4.0 a周期为主，整体无显著变化趋势。夏季降水集中期和集中度受前期、同期大气环流和海温影响明显，整体上夏季降水集中期与5月北美区极涡面积指数显著正相关，而与5月850 hPa西太平洋信风指数和8月斯堪的纳维亚遥相关型指数显著负相关；夏季降水集中度与夏季850 hPa中太平洋信风指数显著正相关，而与6月北非—北大西洋—北美副高脊线位置指数、7月东部型ENSO指数显著负相关，但不同气候指数显著相关区域存在差异。

关键词: 夏季降水, 非均匀性, 降水集中期, 降水集中度, 影响因素