Impact Of Track And Environmental Fields On Climate Variability Of Tropical Cyclone Intensity In The Western Pacifi

Tropical cyclones(TCs)are one of the most destructive natural phenomena on Earth,often causing severe impacts on coastal areas.The predictive skills of TC track forecasting have improved greatly over the past few decades,but little progress has been made in TC strength prediction,and the ability to predict rapid intensification(RI)remains problematic.The TC RI process has also long been one of the biggest forecasting challenges in the business.Further study on the influence of track and different factors on TC intensity and simulation of the contribution of RITC environmental factors can effectively improve the accuracy of TC prediction.In this study,we use a TC intensity model to fully capture the observed climate variability of TC intensity at the western North Pacific basin scale,focusing on the contributions of different factors to climate variability of tropical cyclone intensity in the Western Pacific basin.At the same time,the relevant characteristics of RITC are well reproduced,the contribution and influence of different factors to RITC are investigated,and the main factors affecting the RITC prediction ability are revealed.The main results are as follows:(1)The climate variability of basin-wide TC intensity is largely dependent on the synergistic changes in large-scale environment and TC tracks.Changes in TC tracks generally appear to be the most important factor affecting basin-wide TC intensity on the inter-annual and interdecadal timescales.(2)Different intensities of TC are affected differently by tracks and large-scale environment.Changes in large-scale environment play a limited role especially for weak-to-moderate TCs(i.e.,tropical storms and Cat.1-3 TCs),while comparable impacts of change in TC tracks and large-scale environment are found for intense TCs(i.e.,Cat.4-5 TCs).(3)Given that TC tracks remain unchanged,sensitivity simulations further show that TC duration plays a more crucial role in controlling basin-wide TC intensity than the environmental fields.Moreover,weak-to-moderate TCs appear to be more sensitive to duration than intense TCs,in consistent with the dramatic changes in basin-wide TC intensity for westward TCs that form in the South China Sea and the Philippine Sea with short TC duration.(4)The use of higher-resolution four-dimensional large-scale environment data can well reproduce the inter-annual and interdecadal variation of RITC,thus significantly improving the accuracy of RITC prediction.The track plays a dominant role in its covariation with the SST,and thus is the most important factor to further control the interdecadal variation of the RITC ratio.