2022汤加火山灰羽流的气溶胶光学、微物理和辐射特性

Columnar optical,microphysical and radiative properties of the 2022 Hunga Tonga volcanic ash plumes

作为21世纪乃至近30年最强的火山喷发之一,2022年汤加火山喷发事件已经引起了广泛关注.研究表明,汤加火山喷发所产生的大量火山灰气溶胶突破对流层进入平流层,形成了一个顶部高度约为25~30 km的火山灰羽流.在喷发后的4天内,火山灰羽流在平流层环流的驱动下迅速向西移动了近10000 km.侵入平流层的火山灰气溶胶导致整个澳大利亚北部的大气气溶胶负荷显著增加,气溶胶光学厚度(AOD)在澳大利亚东北部海岸达到1.5,约为侵入前一日的15倍.此次汤加火山灰羽流主要以半径集中在~0.26μm处的细模态颗粒物为主,同时其体积峰值达到0.25μm^(3)μm^(-2).汤加火山喷发对平流层AOD和辐射平衡的影响显著,卫星观测到的平流层AOD的扰动高达0.6.这种扰动在很大程度上解释了区域性地表(大气层顶)的瞬时短波辐射强迫可达-105.0 W m^(-2)(-65.0 W m^(-2)).

The Hunga Tonga-Hunga Ha’apai eruption on January 15,2022 was one of the most explosive volcanic eruptions of the 21st century and has attracted global attention.Here we show that large numbers of the volcanic aerosols from the eruption broke through the tropopause into the lower stratosphere,forming an ash plume with an overshooting top at 25-30 km altitude.In the four days following the eruption,the ash plume moved rapidly westward for nearly 10,000 km under stable stratospheric conditions characterized by strong tropical easterlies,weak meridional winds and weak vertical motion.The intrusion of the ash plume into the stratosphere resulted in a marked increase in atmospheric aerosol loading across northern Australia,with the aerosol optical depth(AOD)observed by satellites and sun-photometers peaking at 1.5 off the coast of northeastern Australia;these effects lasted for nearly three days.The ash plume was characterized by fine-mode particles clustered at a radius of about 0.26μm,with an observed peak volume of 0.25μm^(3)μm^(-2).The impact of the ash plume associated with the Hunga Tonga eruption on the stratospheric AOD and radiative balance in the tropical southern hemisphere is remarkable,with an observed volcanic-induced perturbation of the regional stratospheric AOD of up to 0.6.This perturbation largely explains an instantaneous bottom(top)of the atmosphere radiative forcing of-105.0(-65.0)W m^(-2)on a regional scale.