Climate Change Research ›› 2022, Vol. 18 ›› Issue (3): 319-327.doi: 10.12006/j.issn.1673-1719.2021.212

• Changes in Climate System • Previous Articles     Next Articles

Comparison in developing process between extreme regional flash drought and traditional drought events

YE Tian1,2, YU Jin-Hua1(), SHI Xin-Chi1   

  1. 1 Key Laboratory of Meteorological Disasters, Ministry of Education/ Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science and Technology, Nanjing 210044, China
    2 Ningbo Yinzhou Meteorological Bureau, Ningbo 315194, China
  • Received:2021-09-16 Revised:2021-11-17 Online:2022-05-30 Published:2022-03-01
  • Contact: YU Jin-Hua


The unprecedented drought on record occurred in the Yunnan-Guizhou region of China (YGR) during 2009/2010 and the central-south region of China (CSC) during the summer of 2013 in recent decades. The developing speed of the two drought events was analyzed. Based on the principle of water budget, the physical process that affects the development of drought was diagnosed. The results showed that before the development of CSC drought, temperature increased, evapotranspiration enhanced, soil moisture decreased, and high temperature and precipitation decrease had a triggering effect on the drought; while the decrease of precipitation in YGR caused the drought to develop. The CSC drought event developed rapidly, while the YGR drought event developed slowly. At the same time, the maintenance and recovery time of drought in the former is shorter than that in the latter. These differences are related to the strength of the evapotranspiration process. During the developing stage of the CSC drought event, the evapotranspiration process was strong, with an average of 4.7 mm/d and within 8 days, the soil moisture decreased from 45% to 20%, prompting the rapid formation of drought (flash drought). During the YGR drought developing stage, the evapotranspiration process was weak, with an average of 1.7 mm/d, and the reduction of soil moisture from 45% to 20% lasted more than 2 months (traditional drought). The strength of evapotranspiration is mainly related to the net divergence of water vapor in the regional atmospheric column. During the drought developing stage of CSC, its water vapor net divergence in the atmospheric column reached 3.1 kg/m2 per day, which enhanced the land-atmosphere water exchange, making the evapotranspiration much greater than precipitation, and the rapid decline of soil moisture, accelerating the development of drought. The net divergence of water vapor in the regional atmospheric column of YGR was 1.1 kg/m2 per day, which was only 1/3 of that of CSC, which slowed the development of drought. The net divergence of atmospheric column water vapor of the two drought events mainly occurred in the meridional direction, that is, caused by the relatively strong meridional water vapor outflow at the northern boundary of the region.

Key words: Flash drought, Traditional drought, Soil moisture, Evapotranspiration, Net divergence of atmospheric column water vapor

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