Published 2022-01-01
“…Under the background of global warming,extreme climate events occur frequently.Understanding the change in precipitation from multiple perspectives is of great significance to the utilization of water resources.Specifically,the daily precipitation data at 24 stations along the
Tropic of Cancer in the Longitudinal Range-Gorge Region (LRGR) from 1961 to 2019 are used to calculate 14 wet/dry spell indices.Methods including the revised Mann-Kendall test,Pettitt,and wavelet coherence are adopted to reveal the spatiotemporal variation characteristics of the dry/wet spell indices and their correlation with the large-scale circulation index.The results indicate that:① the wet and dry spells in LRGR of the
Tropic of Cancer show a significant decreasing and increasing trend,respectively,especially in the area west of Yuanjiang River and south of the
Tropic of Cancer.The change in the wet and dry spell indices of most stations is mainly concentrated in 2002.② The frequency of short-duration wet spells and the contribution rate to annual precipitation demonstrate an increasing trend,and those of the medium-long-duration wet spells demonstrate a decreasing trend;the short-duration dry spells are in decline while medium-long-duration dry spells are rising,and the entire region tends to aridification.③ The extreme dry spell index is closely related to ENSO,and it has a negatively correlated co-occurrence cycle of about six years;the extreme wet spell index is closely related to the summer monsoon of the South China Sea,and it has a positively correlated co-occurrence cycle of about eight years.To sum up,the above analysis shows that dry and wet spell indices in LRGR of the
Tropic of Cancer demonstrate an overall trend of aridification,which means that the drought risks are increasing.Their spatiotemporal variation characteristics and local differences may be closely related to the joint influence of the large-scale circulation index,monsoon,and channel-blocking in LRGR.…”
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