Spatiotemporal variation of impervious surface and abnormal climate phenomenon in central Yunnan Urban Agglomeration

Research on the impact of human activities on global climate change is not only the frontier of the discipline, but also the hotspot and difficulty. At present, the research focuses on the climate phenomena of urban impervious surface (IS), such as heat island and rain island effects, while the research on other climate factors has not yet to be carried out. Based on the Global IS Data Set (GAIA) and the China Region High-resolution Surface Meteorological Element Data Set, though the Mann-Kendall (M-K) mutation test and Bayesian model, this paper studied the spatiotemporal variation of IS, the relationship between meteorological elements and IS, and abnormal climatic phenomena for the 34 lakeside urban agglomerations in the Central Yunnan Plateau controlled by the subtropical high from 1985 to 2018. The results showed that the IS area increased by 227.56% compared with that in 1985, with the highest growth rate (89.85 km2/a) in the past 10 years (2007-2018), mainly expanding in S, NE, SE and W directions. During the past 34 years, the climate of the Central Yunnan urban agglomeration experienced three rapid transformation stages: cold and humid (1985-1995), warm and humid (1996-2006), and warm and dry (2007-2018). Compared with the permeable surface, IS had some significant climatic phenomena, including heat island (air temperature increases by 0.63 ℃, long wave increases by 4.49 W m2), rain island (precipitation increased by 38.27 mm), wet island (specific humidity increases by 0.51 g/kg), wind speed low island (wind speed decreased by 0.025 m/s) and air pressure high island (air pressure increased by 602.64 Pa). The spatial distribution of IS has a significant relationship with meteorological elements in a specific interval, such as long wave of 313~329 W m2, specific humidity of 8.9~9.9 g/kg, air pressure of 76235~79946 Pa, short wave of 186~194 W m2, precipitation of 840~876 mm and 876~998 mm, wind speed of 2.08~2.38 m/s and air temperature of 13.85~15.85 ℃. In that interval, meteorological elements respond significantly with the increase of the proportion of IS distribution. The impact of IS on air pressure and humidity has the abnormal characteristics of air pressure-temperature and humidity, which may be caused by subtropical high, elevation and large lakes (lake-land breeze). © 2022, Science Press. All right reserved.