盆地城市下垫面相对湿度变化特征及数值模拟研究——以成都为例

Characteristics and Numerical Simulation of Relative Humidity in Underlying Surface of Basin Cities-Taking Chengdu as an Example

为研究成都地区相对湿度的变化特征及中尺度数值模式不同陆面过程方案对该地区相对湿度的模拟能力,利用成都市2014年地面观测资料和NCEP再分析资料,通过不同时间尺度统计分析和数值模拟试验的方法,对比分析成都相对湿度特征及不同陆面过程方案模拟效果.结论表明:成都市平均相对湿度较高,主要集中在85%~100%;相对湿度季节变化中,秋季相对湿度最大,夏、冬季次之,春季最小;日变化中白天相对湿度较小,夜间较大;四季中相对湿度日变化大致相似,但幅度不同,春季日变化最为显著,冬、夏次之,秋季最小;3种常用的陆面过程参数化方案对成都城市下垫面相对湿度的变化趋势模拟较好,但在极值模拟上有所差异,通过参数评估,5Layer方案对城市下垫面相对湿度模拟效果的最好.

To study the variation characteristics of relative humidity and the simulating capability of relative humidity of process schemes in different land surface while in the mesoscale numerical mode in this field.We took advantage of the ground observation data and reanalysis data and used methods of statistical analysis and numerical simulation experiment in varieties temporal scale to compare and analyze the relative humidity features and simulation effects in different surface process schemes in Chengdu.The results show that:the average relative humidity in Chengdu is comparatively high and is mainly concentrated between 85%and 100%.Relative humidity in autumn is the largest,followed by summer,winter,spring,and in the diurnal variation,relative humidity in daytime is higher than night.Three frequently-used land process parameterization schemes simulated the variation trend of relative humidity of underlying surface excellently in Chengdu,but there are differences in extreme value simulation.Through parameter evaluation,the best simulation effects of relative humidity of city underlying surface is performed by 5Layer scheme.