In situ and space-based observations of the Kelud volcanic plume: The persistence of ash in the lower stratosphere.
In situ and space-based observations of the Kelud volcanic plume: The persistence of ash in the lower stratosphere.
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DOI：
10.1002/2016jd025344
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发表时间：
2016-09-27
期刊：
影响因子：
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通讯作者：
Trepte C
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文献类型：
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作者：
Vernier JP;Fairlie TD;Deshler T;Natarajan M;Knepp T;Foster K;Wienhold FG;Bedka KM;Thomason L;Trepte C
火山喷发是所有时间尺度气候系统自然变化的重要原因。通过气候模型对火山喷发对气候影响的评估几乎普遍认为硫酸盐气溶胶是唯一具有辐射活性的火山物质。我们报告了 2014 年 2 月 13 日克卢德山（印度尼西亚）低层平流层火山物质喷发后，云气溶胶激光雷达和红外探路者卫星观测 (CALIPSO) 卫星上正交偏振云气溶胶激光雷达 (CALIOP) 的卫星观测结果。利用这些观测结果以及在澳大利亚北部的气球现场活动期间使用紧凑型光学背向散射气溶胶探测器 (COBALD) 背向散射探空仪和光学粒子计数器 (OPC) 进行的现场测量，我们发现，半径低于 0.3 µm 的细小火山灰颗粒可能占火山喷发 3 个月后总火山云气溶胶光学深度的 20% 至 28%。在 CALIOP 消光剖面以及 3 个月后 OPC 的气溶胶数浓度测量中观察到灰烬和硫酸盐羽流之间有 1.5-2 公里的分离。由于布鲁尔-多布森环流的向上运动，热带低平流层中半径为 0.3μm 的细灰的沉降速度降低了 50%，导致其寿命加倍。喷发三个月后，我们发现克卢德羽流在大气层顶部存在平均热带晴空辐射强迫，在考虑到火山灰的存在后，接近-0.08 W/m2；比单独考虑硫酸盐时的值高约 20%。因此，火山喷发后的地表冷却可能会受到火山灰持续存在的影响，在气候模拟中应予以考虑。克卢德羽流的现场和星载观测 平流层下部火山灰的持久性 火山灰对气候的影响时间尺度比之前认为的要长
Volcanic eruptions are important causes of natural variability in the climate system at all time scales. Assessments of the climate impact of volcanic eruptions by climate models almost universally assume that sulfate aerosol is the only radiatively active volcanic material. We report satellite observations from the Cloud‐Aerosol Lidar with Orthogonal Polarization (CALIOP) on board the Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite after the eruption of Mount Kelud (Indonesia) on 13 February 2014 of volcanic materials in the lower stratosphere. Using these observations along with in situ measurements with the Compact Optical Backscatter AerosoL Detector (COBALD) backscatter sondes and optical particle counters (OPCs) made during a balloon field campaign in northern Australia, we find that fine ash particles with a radius below 0.3 µm likely represented between 20 and 28% of the total volcanic cloud aerosol optical depth 3 months after the eruption. A separation of 1.5–2 km between the ash and sulfate plumes is observed in the CALIOP extinction profiles as well as in the aerosol number concentration measurements of the OPC after 3 months. The settling velocity of fine ash with a radius of 0.3 µm in the tropical lower stratosphere is reduced by 50% due to the upward motion of the Brewer‐Dobson circulation resulting a doubling of its lifetime. Three months after the eruption, we find a mean tropical clear‐sky radiative forcing at the top of the atmosphere from the Kelud plume near −0.08 W/m2 after including the presence of ash; a value ~20% higher than if sulfate alone is considered. Thus, surface cooling following volcanic eruptions could be affected by the persistence of ash and should be considered in climate simulations. In situ and spaceborne observations of the Kelud plume Persistence of ash in the lower stratosphere Ash can impact climate on longer time scale than previously thought