基于小时降水资料的上海市降水精细特征分析

Fine-scale Characteristics of Rainfall in Shanghai Based on a High-Density AWS Dataset

应用2007-2017年上海地区49个质控后的自动气象站逐时降水数据,揭示了上海地区降水的时空精细特征,结果表明:(1)加密观测资料可捕捉上海地区降水的精细特征,降水分布以东北-西南走向为主,雨带上出现多中心的特征,即中心城区、松江南部和浦东沿海三个高值中心和其他小中心的特征.(2)春夏季降水日变化位相的空间一致性强,均为单峰型变化,春季日降水峰值出现在凌晨,夏季日降水峰值在傍晚.(3)夏季受西南风和热岛效应的共同影响,中心城区下游水陆交界地区(宝山、浦东西部)为短历时降水贡献的高值区.(4)市区站的短历时降水量以下降趋势为主,郊区站的短历时降水量以上升趋势为主,其中城区及其下风向的嘉定区、浦东西部是降水量增加趋势最快的地区,这是由短历时降水频次的增多引起.

The hourly precipitation data of 49 automatic weather stations from 2007 to 2017 in Shanghai isanalyzed.Quality control of automatic weather station data is implemented.The fine-scaled temporal and spatial characteristics of precipitation is revealed in Shanghai.The result shows that,firstly,data of encrypted observed automatic weather stations can capture the finer characteristics of precipitation,and the precipitation distribution is mainly northeast-southwest.There are multi-centers in the rain area,namely high-value center of central city,southern Songjiang,and the coast of Pudong.Secondly,the spatial consistency of the diurnal changes of precipitation in spring and summer is strong,and it’s single-peak changes.The peak of daily precipitation in spring appears in the early morning,and the peak of in summer is in the evening.In summer,under the combined influence of the southwest wind and heat island effect,the sea-land boundary areaand the lower reachof the central urban area(Baoshan and Western Pudong)are high-value areas.Most of them are short-duration precipitation.Thirdly,the trend of short-duration precipitation in urban stations is mainly downward,while the trend in suburban stations is mainly upward.Among them,the downwind direction of urban area are the areas with the fastest increase in precipitation,such as Jiading District and the west of Pudong District.Maybe,it’s caused by the increase of frequency of precipitation.The article further reveals the mechanism of early morning precipitation and the impact of urbanization on the distribution of seasonal precipitation.