Changes in urban-related precipitation in the summer over three city clusters in China
Changes in urban-related precipitation in the summer over three city clusters in China
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DOI：
10.1007/s00704-017-2256-9
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发表时间：
2018-10
影响因子：
3.4
通讯作者：
Deming Zhao;Jian Wu
中科院分区：
文献类型：
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作者：
Deming Zhao;Jian Wu
利用嵌套的第五代Penn State/NCAR中尺度模式3.7版（MM 5 V3.7）研究了不同季风环流背景下，城市地面扩展对中国东部3个城市群（京津冀、长三角和珠三角）夏季降水的影响。利用2000年和2010年的卫星影像数据进行10年的积分，以代表中国城市的表面分布和扩展。降水的变化具有明显的分区域特征，这可以用垂直风速和水汽通量的影响来解释。随着与城市相关的变暖，垂直风运动普遍加强了城市表面扩大的地区。与此同时，不透水表面面积的增加导致雨水快速流入排水沟，Bowen比在城市地区增加，这进一步导致了这些地区局部水分通量的变化。虽然垂直运动和局地蒸发量的变化趋势相似，但降水变化的强度在三个城市群中并不一致，这表明降水的变化不能仅仅由局地蒸发相关的水汽通量的变化来解释。东亚夏季风环流和水汽通量的变化也影响着降水的变化，并表现出明显的次区域特征。因此，城市相关降水对中国3个城市群的影响，应同时考虑局地蒸发和东亚夏季风环流对水汽通量的影响，并根据单个城市的降水变化而变化。
The impacts of urban surface expansion on the summer precipitations over three city clusters [Beijing-Tianjin-Hebei (BTH), the Yangtze River Delta (YRD), and the Pearl River Delta (PRD)] in eastern China under different monsoonal circulation backgrounds were explored using the nested fifth-generation Penn State/NCAR Mesoscale Model version 3.7 (MM5 V3.7), including the urban-related thermal and dynamical parameters. Ten-year integrations were performed using satellite image data from 2000 and 2010 to represent the urban surface distributions and expansions in China. Changes in the precipitation revealed obvious subregional characteristics, which could be explained by the influences of the vertical wind velocity and moisture flux. With urban-related warming, vertical wind motion generally intensified over urban surface-expanded areas. Meanwhile, the increase in impervious surface areas induced rapid rainwater runoff into drains, and the Bowen ratio increased over urban areas, which further contributed to changes in the local moisture fluxes in these regions. The intensities of the changes in precipitation were inconsistent over the three city clusters, although the changes in vertical motion and local evaporation were similar, which indicates that the changes in precipitation cannot be solely explained by the changes in the local evaporation-related moisture flux. The changes in precipitation were also influenced by the changes in the East Asian summer monsoon (EASM) circulation and the corresponding moisture flux, which are expressed in marked subregional characteristics. Therefore, the influence of urban-related precipitation over the three city clusters in China, for which changes in moisture flux from both the impacted local evaporation and EASM circulation should be considered, varied based on the precipitation changes of only a single city.