The relationship between intra-annual density fluctuations of latewood and tropical cyclone precipitation in humid subtropical China

ABSTRACT: Tropical cyclones (TCs), the most destructive natural disasters of this century, have significantly impacted climate change in humid subtropical China. Utilizing high-resolution climate proxy indicators to study the historical activity of TCs can enhance our understanding of climate changes caused by TCs and aid in risk management. Intra-annual density fluctuations (IADFs), reflecting short-term climate events in tree rings, can capture extreme climate data related to the variability of TCs. In this study, we established a chronology of intra-annual density fluctuations of latewood (L-IADFs) frequency of Pinus massoniana Lamb. in humid subtropical China. The frequency of L-IADFs was positively related to the sea surface temperature (SST) in the regions surrounding the South China Sea and the western Pacific from July to September (p < 0.01), August precipitation (r = 0.29, p < 0.05) and Standardized Precipitation Evapotranspiration Index (SPEI) (r = 0.27, p < 0.05) in 1956-2015. By combining the daily growth rates simulated by the Vaganov-Shahikin (V-S) model with the measured positions of L-IADFs (54%-71%) in the tree-ring, it was calculated that L-IADFs occurred mainly from June to September. Linear regression of Tropical Cyclone Precipitation/Total Precipitation (TCP/TP) from July to September explained approximately 30% of the variance in the stable frequency of L-IADFs. Consequently, IADFs can serve as an effective climate proxy to study the impact of TCP in humid subtropical China. Future research can further expand the sample area and tree species, using L-IADFs to reconstruct the history of TCs over a longer timescale, providing a scientific basis for predicting and responding to climate change.