Abstract:

Based on the estimated data of the Sixth Coupled Model Intercomparison Project (CMIP6) conducted by the median resolution model BCC-CSM2-MR from the National Climate Center, methods including bilinear interpolation, trend analysis, anomaly analysis, etc. are used to analyze the changes of extreme precipitation over the Liaohe River Basin under the global warming of 1.5 ℃ and 2.0 ℃. The results show that the anomalous percentage increase of the annual average precipitation over the Liaohe River Basin at the global warming of 1.5 ℃ rises with the increase of emission scenarios, reaching 5.82% under the SSP5-8.5 emission scenario. Under the global warming of 2.0 ℃, the annual and seasonal precipitations over the Liaohe River Basin all show increasing trends, especially for summer precipitation; under the SSP2-4.5 and SSP5-8.5 scenarios, the precipitation decreases from southwest to northeast, with a remarkable increase of over 15% in western Liaoning. Under different emission scenarios, the extreme precipitation indices over the Liaohe River Basin all show increasing trends, with significant growths in daily precipitation intensity, the number of heavy precipitation days, and the proportion of heavy precipitation. With the increase of emission scenarios, the growth rate of extreme precipitation indices rises and is two times more than under the SSP5-8.5 scenario compared to that under the SSP2-4.5 scenario. Under the SSP5-8.5 scenario, the precipitation intensity, the number of heavy precipitation days, the proportion of heavy precipitation, the threshold of heavy precipitation, the maximum number of consecutive wet days, and the maximum 10-day precipitation amount will reach 11.66 mm/d, 15.15 d, 59.08%, 32.94 mm, 9.69 d, 201.29 mm by the end of 21st century, increased by 5.58 mm/d, 5.15 d, 37.08%, 10.15 mm, 5.55 d, 102.86 mm compared to those in the baseline period. Under the global warming of 2.0 ℃, the increases of six extreme precipitation indices are more significant than those under 1.5 ℃ warming, and the extreme precipitation over the Liaohe River Basin shows a consistent increasing trend under the SSP3-7.0 and SSP5-8.5 scenarios.

Key words: BCC-CSM-MR, Global warming, Extreme precipitation index