Researchers predict global warming may intensify Mei-yu weather

Chinese researchers have predicted that the growing global temperature would cause more intense Mei-yu in China's Yangtze River valley region, according to China Science Daily on Monday.

Mei-yu is an important wet weather phenomenon in the middle-lower Yangtze River valley region of China, generally lasting from June 15 to July 10 each year. It has a wide impact on agriculture, the economy, and people's lives.

The researchers from Nanjing University of Information Science and Technology investigated the changes in the characteristics of Mei-yu under global warming and the potential reasons based on observation and reanalysis of data between 1961 and 2022.

According to their recent research article published in the journal National Science Review, notable increasing long-term trends are detected in the number of days without rainfall, the intensity of rainfall events, and the frequency and intensity of extreme precipitation events in the Yangtze River valley region during the Mei-yu period over past decades.

The increasing trend in the number of days without rainfall is attributed to decreased relative humidity over the land surface and a longer time for the air to be replenished with moisture after rainfall events in a warming climate, noted the article.

The increasing trends in the intensity of rainfall events and both frequency and intensity of extreme precipitation events are attributed to the strengthened transient water vapor convergence and convection in the atmosphere under global warming.

The researchers found that the number of days without rainfall, intensity of rainfall events, and frequency of extreme precipitation events will increase in the Yangtze River valley region during the Mei-yu period under the two degrees Celsius warming scenario.

Overall, the intensity of rainfall events during the Mei-yu period has the most significant response to climate change in observations and projections.

The researchers acknowledged the relatively large uncertainty of their study since the research model had limited ability to simulate the change of Mei-yu.