南京城市森林的大气水分特征

Characteristics of Air Moisture in Urban Forest in Nanjing

通过同期(1998～2002年)南京市远郊林区空旷地与市内气象站的日蒸发、降水记录,从两气候要素的多年平均、月变幅、月际差、月极值等方面研究了南京城市林区的大气水分特征,并与市内常年值(1960～1990年)作比较.结果表明,同期年均蒸发量林区比市区低19%,其中差值以秋季最大(25%),春季最小(16%);年均降水量则林区略多4%,又以冬季为最多(10%).同时证实城市森林对近地层大气有补湿功能.

Based on climatological standard normals of evaporation and precipitation at an urban area,Nanjing(1960～1990),the variation of two climatic elements in urban forest in Nanjing were analyzed using daily data measured at two meteorological observing stations(an urban site and an open site of the ecological station) from 1988 to 2002.The characteristics of the air moisture were also described by the normals,annual range,month-to-month difference,amplitude of monthly variation and extremum etc.During the past 15 years,the normals of annual evaporation in the urban forest site were 19% less than that in the urban site,mean differences of seasons at two sites were a maximum(25%) in autumn and a minimum(16%) in spring.The normals of annual precipitation in the urban forest site was 4% more than that in the urban site.The mean difference of seasons at two sites was the most(10%) in winter.The result indicated that the urban forest plays an important role in maintaining air moisture near the surface atmospheric layer.