Abstract：
Evaluating the differences in evapotranspiration between urban and surrounding non-urban areas (i.e., ∆ET) has critical implications for urban ecological planning and water resources management. However, it is unclear how the magnitude of changes in ∆ET caused by urbanization varies under different climatic conditions in China. Here, using the remotely ET estimates at 1 km spatial resolution, we firstly estimated the magnitude of changes in ∆ET and then quantified the main driving factors influencing variations in ∆ET of 7 national-level urban agglomerations (UAs) across China during 2003-2020. Results showed that all annual ETurban values were smaller than ETnon-urban of 7 UAs, and the absolute ∆ET values of cities in South China were generally higher than those in North China. There is an apparent effect of urbanization on ∆ET increase in Guanzhong Plain City Group, Central Plain UA and Guangdong-Hong Kong-Macao Greater Bay Area (GHKMGBA), while ∆ET decrease in Chengdu-Chongqing City Group and Yangtze River Delta (YRDUA) were primarily due to the climate change. The suppressing effects of temperature and NDVI on ∆ET decrease in YRDUA were enhanced, and the promoting effect of GDP on ∆ET increase in GHKMGBA was weakened. Considering nonstationary features, urbanization appears to heighten extreme ∆ET by 0.83 %, 4.83 % and 10.39 % under 5-year, 20-year, and 50-year return periods over all the 7 UAs, respectively. Collectively, our findings confirm that urbanization is a significant factor that leads to ∆ET increase, and the factors affecting the response of urban water circulation system need to be deeply decomposed.
摘要：
评估城市和周围非城市地区的蒸散量差异(即，ΔET）对城市生态规划和水资源管理具有至关重要的意义。然而,目前尚不清楚在中国不同的气候条件下，城市化引起的ΔET变化的幅度如何变化。这里,使用1公里空间分辨率的远程ET估计，我们首先估计了ΔET的变化幅度，然后量化了2003-2020年中国7个国家级城市群（UAs）影响ΔET变化的主要驱动因素。结果表明，所有年度ETnurban值均小于ETnon-urban的7个UA，华南地区城市的ΔET绝对值普遍高于华北地区。城市化对关中平原城市群ET增长有明显影响，中原UA和粤港澳大湾区（GHKMGBA），而成渝城市群和长江三角洲(YRDUA)的ET下降主要是由于气候变化。温度和NDVI对YRDUAET降低的抑制作用增强，GDP对GHKMGBAΔET增长的促进作用减弱。考虑到非平稳特征，城市化似乎使极端ΔET提高了0.83%，5年期以下4.83%和10.39%，20年,以及所有7个UA的50年回报期，分别。总的来说，我们的研究结果证实，城市化是导致ΔET增加的重要因素，影响城市水循环系统响应的因素需要深入分解。
