Two‐dimensional coupled dynamical/chemical/microphysical simulation of global distribution of El Chichón volcanic aerosols
Two‐dimensional coupled dynamical/chemical/microphysical simulation of global distribution of El Chichón volcanic aerosols
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El Chichón 火山气溶胶全球分布的二维耦合动力学/化学/微物理模拟
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
G. Brasseur
中科院分区：
文献类型：
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作者：
X. Tie;X. Lin;G. Brasseur
我们已经开发了一个耦合的二维动力/化学/微物理模式来研究平流层硫酸盐气溶胶的全球分布。特别是，我们用这个模型来模拟1982年4月在墨西哥的El Chichon火山爆发后的火山气溶胶的全球分布。模拟的背景气溶胶分布是高度分散的，但也注意到一个轻微的纬度梯度。在北方半球的中纬度地区，计算的背景气溶胶表面积和质量分别约为0.7 - 1.0 μm2/cm 3和0.3 - 0.5 ppm，与现有的观测结果相当一致。1982年4月El Chichon火山爆发后，热带20 - 25公里高度的平流层气溶胶负荷迅速增加。热带地区的气溶胶面积在平流层下部达到最大值50 μm2/cm 3，约为背景气溶胶面积的70-100倍。火山爆发六个月后，火山气溶胶扩散到全球，但仍集中在热带地区。喷发后一年，增强的气溶胶开始减少，并趋于均匀分布在平流层下部。爆发后两年，全球气溶胶约为平流层下部背景气溶胶负荷的5倍。在后火山时期，热带地区气溶胶的e-折叠时间约为10个月。与观测结果（在空间、时间和尺寸分布方面）相比，该模型定量地模拟了火山气溶胶云的演变。因此，这一模式可以成为研究火山爆发对平流层臭氧和气候影响的有用工具。此外，我们发现，对于一个模型模拟，其中气相SO2是唯一的物质喷出的喷发，该模型大大低估了火山气溶胶负荷。因此，我们预期硫酸盐气溶胶粒子的直接喷射可能是一个非常重要的过程。
We have developed a coupled two-dimensional dynamical/chemical/microphysical model to study the global distribution of stratospheric sulfate aerosols. In particular, we use this model to simulate the global distribution of volcanic aerosols after the eruption of El Chichon in Mexico in April 1982. The simulated background aerosol distributions are highly dispersed, while a slight latitudinal gradient is also noticed. The calculated background aerosol surface area and mass are about 0.7 to 1.0 μm2/cm3 and 0.3 to 0.5 parts per billion by mass, respectively, at midlatitude in the northern hemisphere, in fair agreement with available observations. After the eruption of El Chichon in April 1982, the stratospheric aerosol load rapidly increases in the tropics at an altitude of 20 to 25 km. The aerosol area in the tropics reaches a maximum 50 μm2/cm3 in the lower stratosphere, which is about 70–100 times the background aerosol area. Six months after the eruption, volcanic aerosols spread out globally but are still centered in the tropics. One year after the eruption the enhanced aerosol begins to decrease and tends to become uniformly distributed in the lower stratosphere. Two years after the eruption the global aerosol is about 5 times the background aerosol load in the lower stratosphere. The e-folding time of the aerosol load is about 10 months in the tropics during the postvolcanic period. Compared to observations (in terms of spatial, temporal, and size distributions), the model quantitatively simulates the evolution of volcanic aerosol clouds. Thus this model could be a useful tool for studying the impacts of volcanic eruptions on stratospheric ozone and climate. Moreover, we find that for a model simulation in which the gas phase SO2 is the only material ejected by the eruption, the model substantially underestimates the volcanic aerosol load. Thus we expect that the direct ejection of sulfate aerosol particles may be a very important process.