Model physics and chemistry causing intermodel disagreement within the VolMIP-Tambora Interactive Stratospheric Aerosol ensemble
Model physics and chemistry causing intermodel disagreement within the VolMIP-Tambora Interactive Stratospheric Aerosol ensemble
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DOI：
10.5194/acp-21-3317-2021
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发表时间：
2021-03-04
影响因子：
6.3
通讯作者：
Toon, Owen B.
中科院分区：
文献类型：
--
作者：
Clyne, Margot;Lamarque, Jean-Francois;Toon, Owen B.
作为火山强迫气候响应模式比对项目（VolMIP）的一部分，几个气候模拟中心使用互动式平流层气溶胶模式进行了协调的预研究实验，模拟了类似1815年坦博拉火山喷发的火山气溶胶云（VolMIP-Tambora ISA集合）。当火山气溶胶云被交互模拟时，预研究提供了辅助能力来评估一次向平流层注入的大型赤道喷发的辐射强迫模式间多样性。对VolMIP-Tambora ISA集合的初步分析表明，在平流层全球平均气溶胶光学深度（AOD）的模式之间存在很大差异。在这项研究中，我们现在表明，参与模式之间的平流层全球平均AOD差异主要是由于气溶胶大小的差异，我们在这里通过有效半径跟踪。我们确定了某些模型中缺失的特定物理和化学过程，或者模型之间参数化的差异，这些过程共同导致了有效半径的差异。特别是，我们的分析表明，在大量火山注入二氧化硫（SO2）之后，相互跟踪羟基自由基（OH）化学是允许适当模拟硫酸盐形成时间尺度的重要因素。此外，根据硫酸盐形成的时间尺度，SO2是在火山喷发位置附近的单个模型网格单元中注入，还是在地球周围的纵向平均带中注入，可能会导致有效半径和随后的AOD存在很大差异。
As part of the Model Intercomparison Project on the climatic response to Volcanic forcing (VolMIP), several climate modeling centers performed a coordinated pre-study experiment with interactive stratospheric aerosol models simulating the volcanic aerosol cloud from an eruption resembling the 1815 Mt. Tambora eruption (VolMIP-Tambora ISA ensemble). The pre-study provided the ancillary ability to assess intermodel diversity in the radiative forcing for a large stratospheric-injecting equatorial eruption when the volcanic aerosol cloud is simulated interactively. An initial analysis of the VolMIP-Tambora ISA ensemble showed large disparities between models in the stratospheric global mean aerosol optical depth (AOD). In this study, we now show that stratospheric global mean AOD differences among the participating models are primarily due to differences in aerosol size, which we track here by effective radius. We identify specific physical and chemical processes that are missing in some models and/or parameterized differently between models, which are together causing the differences in effective radius. In particular, our analysis indicates that interactively tracking hydroxyl radical (OH) chemistry following a large volcanic injection of sulfur dioxide (SO2) is an important factor in allowing for the timescale for sulfate formation to be properly simulated. In addition, depending on the timescale of sulfate formation, there can be a large difference in effective radius and subsequently AOD that results from whether the SO2 is injected in a single model grid cell near the location of the volcanic eruption, or whether it is injected as a longitudinally averaged band around the Earth.