摘要
The thermodynamic state of the tropical atmosphere plays an important role in the development of tropical cyclone(TC)intensity.This study reports new results that demonstrate a negative association between eastern Pacific TC intensity in offshore regions and dust aerosol optical depth(AOD)for the years 1980–2019.At the same time,a negative response of cloud water in the lower troposphere to dust AOD is reported by analyzing MERRA-2 reanalysis data and GCM simulations from CMIP6.This response can be explained by the dust semi-direct effect,in which dust aerosols absorb solar radiation,promoting the evaporation of clouds.In principle,this aerosol-driven vaporization modification could affect the enthalpy of the air surrounding a TC.Using potential intensity theory,the authors demonstrate that change in TC intensity related to dust AOD conditions is a consequence of the anomalous enthalpy of the air surrounding a TC caused by the dust semi-direct effect.
热带地区大气的热力学状态对台风的发展起着重要作用.本项研究结果表明,东太平洋台风强度与沙尘AOD之间存在一定的负相关.同时,MERRA-2再分析数据和CMIP6的GCM模拟的分析结果,都表明了低层大气中云对沙尘AOD的负响应.沙尘颗粒物的准直接辐射效应可以解释上述响应:沙尘颗粒物吸收太阳辐射,并用此热量促进云层蒸发.理论上,这种气溶胶驱动的汽化作用会影响台风周围空气的焓.根据台风的潜在强度理论,与沙尘相关的台风强度变化,实则是沙尘的准直接辐射效应引起的台风周围空气焓值变化的结果.
基金
This work was supported by National Natural Science Foundation of China[grant numbers 41675062 and 41375096]
the Research Grants Council of the Hong Kong Special Administrative Region,China[project numbers CityU 11306417 and 11335316].
