Characterisation of a stratospheric sulfate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry
Characterisation of a stratospheric sulfate plume from the Nabro volcano using a combination of passive satellite measurements in nadir and limb geometry
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DOI：
10.5194/acp-14-8149-2014
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发表时间：
2014-08
影响因子：
6.3
通讯作者：
M. P. D. Vries;S. Dörner;J. Puķı̄te;C. Hörmann;M. Fromm;T. Wagner
中科院分区：
文献类型：
--
作者：
M. P. D. Vries;S. Dörner;J. Puķı̄te;C. Hörmann;M. Fromm;T. Wagner
抽象的。2011年6月12日开始的纳布罗火山（厄立特里亚）喷发导致大量二氧化硫进入平流层下部。随后形成的硫酸盐气溶胶可以在喷发后的几个月内检测到。一般认为，平流层中硫酸盐气溶胶的形成是一个相对缓慢的过程，但在爆炸性喷发的羽流中，已经看到大量的气溶胶在几个小时内形成。我们表明，硫酸盐气溶胶存在于平流层下部的纳布罗火山爆发的发病数小时内。证据来自SCIAMACHY、GOME-2和OMI的最低紫外线气溶胶指数（UVAI）和二氧化硫测量，以及SCIAMACHY的临边气溶胶测量。硫酸盐羽流在大洋米氏带的西部显示出负的紫外线吸收指数，而在东部显示出正的紫外线吸收指数-这种效应是由于紫外线吸收指数对视角的强烈依赖性造成的，而且只能由高海拔（>11公里）、非吸收性（单次散射系数>0.97）气溶胶羽流造成。对于检索的气溶胶廓线从临边测量，气溶胶羽流的水平尺寸和位置需要考虑，否则消光和层高度可能会被低估。通过将最低点SO2柱密度和紫外可见光指数与临边气溶胶廓线相结合，可以在6月13日至17日期间跟踪纳布罗平流层羽流，之后较低高度爆炸产生的羽流开始干扰信号。我们的研究结果是一致的地面激光雷达和太阳光度计数据从MPLNET/AERONET站在以色列和卫星载的CALIOP激光雷达的数据。
Abstract. The eruption of the Nabro volcano (Eritrea), which started on 12 June 2011, caused the introduction of large quantities of SO2 into the lower stratosphere. The subsequently formed sulfate aerosols could be detected for several months following the eruption. It is generally assumed that the formation of sulfate aerosols in the stratosphere is a relatively slow process, but in plumes from explosive eruptions significant amounts of aerosols have been seen to form within a few hours. We show that sulfate aerosols were present in the lower stratosphere within hours of the onset of the eruption of Nabro. Evidence comes from nadir UV Aerosol Index (UVAI) and SO2 measurements by SCIAMACHY, GOME-2 and OMI, and limb aerosol measurements by SCIAMACHY. The sulfate plume displays negative UVAI in the western part of OMI's swath and positive UVAI in the eastern part – an effect that is due to the strong viewing angle dependence of UVAI and can only be caused by a high-altitude (>11 km), non-absorbing (single-scattering albedo >0.97) aerosol plume. For the retrieval of the aerosol profile from limb measurements, the horizontal dimensions and the position of the aerosol plume need to be taken into account, otherwise both extinction and layer height may be underestimated appreciably. By combining nadir SO2 column density and UVAI with limb aerosol profiles, a stratospheric plume from Nabro could be tracked from 13 to 17 June, before the plumes from later, lower-altitude explosions started interfering with the signal. Our findings are in agreement with ground-based lidar and sun-photometer data from an MPLNET/AERONET station in Israel and with data from the satellite-borne CALIOP lidar.