Precipitable water and CAPE dependence of rainfall intensities in China
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The influence of temperature on precipitation in China is investigated from two aspects of the atmospheric water cycle: available water vapor and atmospheric instability. Daily observations are used to analyze how rainfall intensities and its spatial distribution in mainland China depend on these two aspects. The results show that rainfall intensities, and especially rainfall extremes, increase exponentially with available water vapor. The efficiency of water vapor conversion to rainfall is higher in northwestern China where water vapor is scarce than in southeastern China where water vapor is plentiful. The results also reveal a power law relationship between rainfall intensity and convective instability. The fraction of convective available potential energy (CAPE) converted to upward velocity is much larger over southeastern China than over the arid northwest. The sensitivities of precipitation to temperature-induced changes in available water vapor and atmospheric convection are thus geographically reciprocal. Specifically, while conversion of water vapor to rainfall is relatively less efficient in southeastern China, conversion of CAPE to upward kinetic energy is more efficient. By contrast, in northwestern China, water vapor is efficiently converted to rainfall but only a small fraction of CAPE is converted to upward motion. The detailed features of these relationships vary by location and season; however, the influences of atmospheric temperature on rainfall intensities and rainfall extremes are predominantly expressed through changes in available water vapor, with changes in convective instability playing a secondary role.
KeywordsConvective instability Available water vapor Rainfall intensity China
We gratefully acknowledge NOAA National Centers for Environment Information for providing public access to the IGRA radiosonde data ( https://doi.org/10.7289/V5X63K0Q), which are available at https://www.ncdc.noaa.gov/data-access/weather-balloon/integrated-global-radiosonde-archive. We would like to thank National Meteorological Information Center of Chinese Meteorological Administration for providing daily gauge-based precipitation data (http://data.cma.cn/en). This work was supported by the Ministry of Science and Technology of China (2014CB441303).
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