Relationship of extreme precipitation, surface air temperature, and dew point temperature across the Tibetan Plateau

Global warming is expected to have profound socio-economic and environmental consequences, and one of the key concerns is extreme precipitation. The classic theory indicates that the variation of extreme precipitation will follow the thermodynamically based Clausius-Clapeyron relation (increasing at a rate of approximately 7%/°C). However, the interaction and the seasonal variation of the relationship between extreme precipitation and temperature has not been thoroughly integrated. Here, we use quantile regression and the binning method to process meteorological station data and the reanalysis data from 78 stations on the Tibetan Plateau (TP), and estimate the sensitivity and dependency of extreme precipitation to both surface air temperature and dew point temperature. The results indicate that the majority of the meteorological stations experience a positive scaling between extreme precipitation and surface air temperature, with the median of surface air temperature scaling close to 2.5%/°C. With regard to scaling during individual seasons, 80% of stations possess negative scaling of the 99th percentile of extreme precipitation with temperature in summer, while 63 stations (81% of the total) display positive trends in winter, and the other 19% have negative scaling. A stronger scaling (3.5%/°C) occurs between dewpoint temperature and extreme precipitation. For surface air temperature < −3 °C and > 8 °C, relative humidity decreases with increasing temperature and dewpoint depression increases, so dewpoint temperature increases more slowly than temperature, resulting in the stronger scaling relationship with dewpoint temperature. The depression of dewpoint temperature presents a slight decrease in −3–8 °C interval, but dewpoint temperature increases faster than other intervals, and the scaling relationship of dewpoint temperature is consistently larger than with surface air temperature due to the small increasing rate with dewpoint temperature and increasing extreme precipitation intensity. Our results emphasize that the increasing temperature has clear scaling and seasonal relationship with extreme precipitation on the TP, and the atmospheric humidity variation has an effect on the overall difference in the scaling relationships of extreme precipitation with surface air temperature and dewpoint temperature. The variations of seasonality and the effects of atmospheric humidity for extreme precipitation should also be carefully considered in future research.