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Attributing extreme precipitation in South China Pearl River Delta region to anthropogenic influences based on pseudo global warming method
  • Francis Tam,
  • Sai Ming LEE
Chinese University of Hong Kong

Corresponding Author:[email protected]

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Francis Tam
Chinese University of Hong Kong
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Sai Ming LEE
Hong Kong Observatory
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In the context of the human-induced warming climate, a greater amount of water vapor will be hold in the atmosphere, leading to more-intense precipitation extremes on global scale. However, there is no consensus yet on how much changes in those extremes are attributable to human influences on a regional basis. In this study, human-influenced variations in frequency and intensification of precipitation extremes over the South China (SC) Pearl River Delta (PRD) region are quantitatively assessed using the cloud-resolving Weather Research and Forecasting (WRF) model based on the reversed pseudo global warming (PGW) method. Forty extreme precipitation (95th percentile) events that occurred in different seasons for 1998-2018 over the PRD region are identified and dynamically downscaled by the WRF. The model was forced with present and counterfactual initial and boundary conditions, with the latter being derived by subtracting the CMIP5 7-model ensemble mean changes from ERA-Interim reanalysis. As inferred from these global models, the 1000-500 hPa tropospheric temperature has warmed by ~0.9 (0.8) ℃ over PRD (SC) due to human influences. Preliminary results show that such human-induced warming can lead to about 20% or more increase in the frequency of daily rainfall in PRD, with the greater enhancement in non-rainy season events. Human impacts also intensify the 95th percentile of PRD daily rainfall by around 12% (8%) in the non-rainy (rainy) season. This super-CC increase of non-rainy season cases probably implies the possible dynamic feedbacks, in addition to moisture-related thermodynamic effect in human-influenced extreme precipitation variations.