| Tropical cyclone(TC)often causes severe impacts on coastal areas,and the accuracy of TC activity forecasts is crucial for disaster prevention.As the research on how aerosols affect the weather and climate system is further developed,the influence of aerosols on TC activity has also received more and more attention.An in-depth study of the statistical relationship between aerosols and TC activity and the physical link between them,and an enhanced understanding of the key physical processes,will help clarify the understanding of how aerosols affect TC activity,as well as deepen the study of TC activity and help improve TC forecasting capability.This study focuses on eastern China,a region with large aerosol load,and presents the specific influence of aerosols in this region on TC activities in the northern hemisphere,and through the comprehensive analysis of environmental impact factors and dynamic latent genesis indices,elucidates the physical processes of aerosol-influenced TC genesis,emphasizes the potential influence of aerosol in eastern China on TC activities in the northern hemisphere,and thus improves the understanding of the changes in TC activities in the northern hemisphere.The potential influence of aerosol on TC activity in the northern hemisphere is emphasized,thus improving the understanding of TC activity changes in the northern hemisphere.Several conclusions present as follows:(1)The aerosol in eastern China dominates the Northern Hemisphere aerosol cooling climate effect.The significant aerosol cooling of the Northern Hemisphere summer surface results in significant interhemispheric temperature differences(ITD).As a result of the ITD,the trans-equatorial airflow with high and low level heterogeneity suppresses the upward motion of the NH TC formation zone in the Northern Hemisphere summer and enhances the vertical shear of the NH TC formation zone.(2)A significant negative correlation between the aerosol and the frequency of Western North Pacific(WNP)TC genesis in eastern China from 2003 to 2020 is revealed.Anomalous WNP TC tripolar modes exist in years with higher aerosol in eastern China,with decreasing TCs in the South China Sea/Philippines and the southeastern Northwest Pacific and increasing TCs in the central Northwest Pacific.Changes in large-scale environmental field conditions associated with aerosol changes in eastern China are the main reason for the changes in the frequency distribution of WNP TC production,and the changes in the large-scale environmental field are found to be closely related to the aerosol-driven negative-phase Pacific meridional mode(PMM).the effect of aerosol on the temperature difference between hemispheres can also affect the WNP local environmental field.(3)A potential link between aerosol in eastern China and the frequency of Eastern North Pacific(ENP)TC production during 2003-2020 is identified.There is a significant decrease in TC generation frequency in the offshore sea of southeastern America(region between110-120°W,10-20°N)in years when the aerosol in eastern China is large.A significant correlation was found between the frequency of TC generation and local SST in this region.Aerosols in eastern China affect the development of PMM negative phase,thus reducing local SST in the eastern Pacific Ocean and creating thermal conditions unfavorable to TC genesis in ENP.(4)A significant negative correlation was found between aerosol loading in eastern China and the frequency of TC generation in the basin of the Gulf of Mexico and nearshore basin to the southeastern United States from 2003 to 2020.Vertical motion and vertical wind shear changes associated with aerosol anomalies in eastern China are important dynamic factors affecting TC generation.The climatic effects of aerosols in eastern China weaken the Hadley circulation in the North Atlantic region,weaken the upward motion,strengthen the vertical wind shear and reduce the humidity in the middle and lower troposphere,forming environmental conditions unfavorable to TC generation. |
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