Abstract
Using the ERA5 (the fifth major global reanalysis produced by the European Centre for Medium-Range Weather Forecasts) data and the T-PCA (Principal Component Analysis in T-mode) objective classification method to classify the 850-hPa geopotential height, we summarize four conceptual models of large-scale synoptic weather types over East Asia. By combining this with the daily precipitation observation data of 36 meteorological stations in Guangdong, South China, during summer (June to August) of 2014–2018, we found that summer precipitation in Guangdong Province is closely related to the position of the northwestern Pacific subtropical high and the strong upward motion of the warm airflow over the Pearl River Delta. It is further revealed the regulation effect of different weather patterns on summer precipitation in Guangdong Province and their urban–rural differences. More specifically, both urban and rural areas have a decreasing proportion of light rainfall and an increasing proportion of heavy and torrential rainfall, which are mainly regulated by the trend of frequency changes of four different weather types: Type 1 (47.39%) and Type 2 (32.39%) days are decreasing year by year, modulating the trend of light rainfall, while Type 3 (13.26%) and Type 4 (6.96%) days are steadily increasing, dominating the trend of heavy rainfall. In addition, it was further found that the frequency of light rainfall is decreasing more significantly in cities compared to that in rural areas, while the proportion of heavy and stormy rainfall is increasing more significantly, which is closely related to the effects of rapid urbanization.
Highlights
Precipitation is an important factor reflecting the atmospheric circulation characteristics and climate change
The 850-hPa geopotential height were classified by using the T-PCA objective classification method based on the ERA5 reanalysis data
This study revealed the urban–rural differences in summer precipitation in Guangdong and the modulating effects of the different weather types on precipitation and their urban–rural differences, with the following main conclusions: Guangdong, South China, is mainly controlled by four weather types at the 850-hPa geopotential height
Summary
Precipitation is an important factor reflecting the atmospheric circulation characteristics and climate change. Uneven spatial distribution and temporal variability of extreme precipitation can directly or indirectly cause serious losses to agricultural production and adverse impacts on human society. On 21 July 2012, Beijing and its surrounding areas were hit by extreme heavy rainfall, resulting in flooding, and traffic congestion, with direct and indirect economic losses. The level of damage caused by heavy rainfall is increasing. Improving our understanding of precipitation—especially its characteristics in mega-city clusters—can help us to develop more advanced early warning and emergency response initiatives in the face of large-scale disasters, as well as better post-disaster recovery actions
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