中国东部地区冬季和夏季地面湿度空间分布特征的对比分析

利用中国东部地区315个台站1963~2012年月平均地面观测资料,揭示了东部地区冬季和夏季地面比湿(SH)和相对湿度(RH)多年平均值及其变率的空间分布特征,并分析和比较了地理因素(经度、纬度和海拔高度)对其空间分布的影响。结果表明:1)在冬季,SH(0.4~7 g kg-1)以秦岭-淮河线为界,呈现出"北低南高"的分布特征;RH(41%~82%)则呈现出"南北高、中间低"的分布特征;一般冬季地面湿度相对较低的地区其变化幅度相对较大。2)在夏季,SH(7~20 g kg-1)整体上明显大于冬季,RH(44%~89%)则与冬季差异不大,均呈现由东南部沿海向西北内陆递减的分布特征;同样夏季地面湿度较低的地区通常其变化幅度也相对较大。3)东部地区冬季地面湿度空间分布受地理因素影响,其中纬度是最主要的影响因素,经度次之,海拔高度对其整体分布影响不明显,且地理因素对冬季SH的回归效果明显好于对冬季RH的回归效果。4)东部地区夏季地面湿度空间分布受地理因素影响较冬季显著,纬度同样是影响夏季地面湿度最主要的因素,但海拔高度对夏季SH、经度对夏季RH的影响程度较冬季增大,且地理因素对夏季SH的回归效果同样好于对RH的回归效果。

Comparison between the Spatial Distribution of Surface Humidity in Winter and Summer over East China

Based on the monthly mean surface dataset from 315 weather stations during 1963-2012, the spatial distribution characteristics of specific humidity (SH) and relative humidity (RH) over East China are analyzed. The results are as follows: 1) In winter months, the mean values of SH (0.4-7 g kg^-1) show zonal spatial distribution decreasing with latitude, while the mean values of RH (41%-82%) present the feature of a lower value in the central than in the northern and southern sides of the region. The relative variability of SH and RH are also discussed, revealing higher values of relative variability in areas with a lower value of SH and RH during the winter months. 2) In summer months, the values of SH (7-20 g kg^-1) are generally higher than in winter months, but the RH values (44%-89%) have little changes. Both SH and RH decrease from the southeast coast to northwest inland over East China. The spatial distribution of relative variability in summer months shows the lower mean values of surface humidity denoting lower mean values of SH or RH denoting higher values of SH or RH relative variability. 3) The spatial distribution of surface humidity in winter is deeply affected by the geographical location over East China. Specifically, surface humidity in winter is mainly dependent on latitude, but longitude also plays a role. However, surface humidity is not sensitive to elevation. Moreover, the distribution characteristics of SH are more dependent on the geography than RH in winter. 4) In contrast, the influence of geographical factors on the surface humidity distribution is more obvious in summer than in winter. In summer, surface humidity is also largely dependent on latitude, but the influence of elevation on SH and longitude on RH becomes more significant in summer than in winter. The geographical characteristics of the SH distribution are also stronger than for RH in summer.