基于质心分析的淮河流域降水时空分布特征

为定量表征淮河流域降水量非均匀性特征,建立年降水质心时间指标,以概化年内降水过程时间分布,从时域、空域、频域3个维度解析流域近55 a降水质心时间的总体格局与演变规律。结果表明:各典型站点近55a降水质心时间序列中全部存在28a的第一主周期;年降水质心时间序列突变年份多发生于1975—1989年,突变主要集中于淮河上中游地区;年降水质心时间序列多呈现不显著的增加趋势,说明流域大部分地区年降水集中期有微弱的后移倾向;年降水质心时间随纬度增加而呈现明显的后推趋势,流域南北地区年降水质心时间可相差20 d左右,经度变化对年降水质心时间没有明显影响;淮河流域暴雨与大雨质心时间普遍迟于其他等级年降水质心时间,流域年降水质心时间对暴雨、大雨较为敏感。

Spatial and temporal distribution characteristic of precipitation in the Huaihe River Basin based on centroid analysis

In order to quantitatively characterize the non-uniformity of precipitation in the Huaihe River Basin, the centroid time of annual precipitation was established to generalize the time distribution of precipitation process. The overall pattern and evolution characteristics of precipitation concentration period in the past 55 years was analyzed from three aspects: time domain, space domain and frequency domain. The results show that: (a)the first main period of the centroid time of annual precipitation is 28 years in all selected stations, the mutation mostly happened in the southern area of the upper reaches of Huaihe River around from the late 1970s to the mid or late 1980s, and the time series of centroid time of annual precipitation has an increasing trend but not significant, which indicates that there was a slight backward in most areas of the watershed. (b)The centroid time of annual precipitation has a significant backward trend with the increase of the latitude, and the difference is about 20 days from the south to the north. The change of centroid time of annual precipitation has no correlation with the longitude, which explains that no obvious difference exists between the east and the west. (c)The centroid time of storm and heavy rain is generally later than the other grade of annual precipitation, to which the centroid time of annual precipitation is sensible.