采用1960-2007年上海地区11个站的逐日降水资料,基于空间标准化相对降水量,研究上海城市化进程不同阶段的降水空间分布变化。结果表明,伴随城郊城市化进程差异的显著加快,上海年降水量的空间差异增大。城市化进程的快速增长期,年降水量和暴雨以上的强降水日数呈现出明显的城市雨岛分布特征;在城市化进程的缓慢增长期,该特征则不明显。年降水量变化趋势的空间分布格局在城市化进程的不同阶段也发生了变化。上海地区年降水总量从城市化进程缓慢增长期的城郊空间一致性变化趋势转变为快速增长期的不一致变化趋势,且后一阶段的中心城区(郊区)年降水量呈增多(减少)趋势。此外,城市化进程的快慢对于冬、春季节降水量的空间分布没有明显的影响;但在城市化进程的快速增长期,夏、秋两季(特别是夏季)降水量的空间差异呈现明显的城市雨岛特征。
Using daily rainfall data of 11 observatory stations over Shanghai for the period of 1960-2007, spatial differences of rainfall over Shanghai region during periods with slow and rapid acceleration urbanization respectively are investigated basing on spatial standard deviation of rainfall and its relative variables. Results show that spatial difference increases with rapidly accelerating of urbanization. Spatial distributions of annual rainfall and rainstorm frequency exhibit distinct urban "rain-island" feature during rapid acceleration period of urbanization while the case is opposite during slow acceleration period. Change of spatial distribution for trend of annual rainfall also takes place during different periods. Specifically, variation of annual rainfall exhibits symmetric trend over Shanghai region for the slow urbanization period. But inconsistent spatial distribution of variation trend has taken placed over central city and suburbs of Shanghai during the latter stage. Since the speeding up of urbanization, annual rainfall amount over central city of Shanghai has increasing trend while those in suburbs show decreasing trend. In addition, as far as different seasons concerned, speed of urbanization exerts insignificant influences on spatial distribution of rainfall during winter and spring. On the contrary, rainfall during summer and autumn (especially summer) shows clear character of urban rainfall island during rapid urbanization period.