Radiative forcing in the ACCMIP historical and future climate simulations
Radiative forcing in the ACCMIP historical and future climate simulations
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DOI：
10.5194/acp-13-2939-2013
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发表时间：
2013-01-01
影响因子：
6.3
通讯作者：
Lo, F.
中科院分区：
文献类型：
--
作者：
Shindell, D. T.;Lamarque, J. -F.;Lo, F.
大气化学和气候模式相互比较项目（ACCMIP）研究了当前气候模式中气候变化的短期驱动因素。在这里，我们评估了10个ACCMIP模式，包括气溶胶，其中8个也参加了耦合模式相互比较项目第5阶段（CMIP 5）。这些模式再现了当今总气溶胶光学厚度（AOD）相对较好，虽然许多是偏低。然而，来自各个气溶胶组分的贡献是相当不同的，并且大多数模式低估了东亚气溶胶光学厚度。模型捕捉大多数1980-2000年的AOD趋势，但低估了增加在黄海/东海。我们研究了直接辐射强迫（RF）和包括快速调整的强迫（有效辐射强迫; ERF，包括直接和间接影响）。模式的全天1850 - 2000年全球平均年平均总气溶胶RF为（平均值;范围）-0.26 Wm（-2）; -0.06至-0.49 Wm（-2）。根据模式捕捉观测到的气溶胶光学厚度的技巧进行筛选，得到的最佳估计值为-0.42 Wm（-2）; -0.33至-0.50 Wm（-2），包括某些模式中缺失的气溶胶成分的调整。许多ACCMIP和CMIP 5模型似乎产生的气溶胶RF比这一最佳估计要小得多。气候反馈对模拟的历史气溶胶RF有很大贡献（35 - 58%）。1850年至2000年气溶胶ERF为-1.17 Wm（-2）; -0.71至-1.44 Wm（-2）。因此，调整，包括云，通常会导致更大的强迫比直接射频。尽管如此，在有大量强迫的地区，相对于平均值的多模式扩散对于ERF和RF通常是相同的，甚至更小。1850 - 2000年气溶胶RF和ERF最大负值出现在欧洲、南亚、东亚和北美上空和附近。然而，ERF是积极的撒哈拉，喀喇昆仑，高纬度南部，特别是北极。全球气溶胶RF峰值在1980年左右的大多数模式，此后下降，只有弱敏感性的代表浓度路径（RCP）。然而，一个模型预测近似稳定的RF水平，而两个模型由于硝酸盐（不包括在大多数模型中）而显示出越来越负的RF。相反，气溶胶ERF在1980年至2000年期间变得更负。在此期间，亚洲排放量的增加似乎对气溶胶ERF的影响大于欧洲和北美的减少，因为它们位于大型，相对原始的太平洋的上风。在ACCMIP模式的CMIP 5子集中，历史气溶胶ERF和气候敏感性之间没有明确的关系。在ACCMIP/CMIP 5模式中，历史气溶胶ERF约为-0.8至-1.5 Wm（-2），与观测到的历史变暖最为一致。气溶胶ERF掩盖了世纪末和21世纪初在全球范围内的温室效应。从区域来看，气溶胶ERF非常大，以至于到1980年，大多数工业化和生物质燃烧地区的净强迫都是负的，但到2000年，只有东亚和东南亚的净强迫仍然为负。到1980年，大多数沙漠、北极、澳大利亚和大多数热带海洋的净强迫都是强正的。此后，正强迫的大小和覆盖面积都稳步扩大。
The Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP) examined the short-lived drivers of climate change in current climate models. Here we evaluate the 10 ACCMIP models that included aerosols, 8 of which also participated in the Coupled Model Intercomparison Project phase 5 (CMIP5).The models reproduce present-day total aerosol optical depth (AOD) relatively well, though many are biased low. Contributions from individual aerosol components are quite different, however, and most models underestimate east Asian AOD. The models capture most 1980-2000 AOD trends well, but underpredict increases over the Yellow/Eastern Sea. They strongly underestimate absorbing AOD in many regions.We examine both the direct radiative forcing (RF) and the forcing including rapid adjustments (effective radiative forcing; ERF, including direct and indirect effects). The models' all-sky 1850 to 2000 global mean annual average total aerosol RF is (mean; range) -0.26 Wm(-2); -0.06 to -0.49 Wm(-2). Screening based on model skill in capturing observed AOD yields a best estimate of -0.42 Wm(-2); -0.33 to -0.50 Wm(-2), including adjustment for missing aerosol components in some models. Many ACCMIP and CMIP5 models appear to produce substantially smaller aerosol RF than this best estimate. Climate feedbacks contribute substantially (35 to -58%) to modeled historical aerosol RF. The 1850 to 2000 aerosol ERF is -1.17 Wm(-2); -0.71 to -1.44 Wm(-2). Thus adjustments, including clouds, typically cause greater forcing than direct RF. Despite this, the multi-model spread relative to the mean is typically the same for ERF as it is for RF, or even smaller, over areas with substantial forcing. The largest 1850 to 2000 negative aerosol RF and ERF values are over and near Europe, south and east Asia and North America. ERF, however, is positive over the Sahara, the Karakoram, high Southern latitudes and especially the Arctic.Global aerosol RF peaks in most models around 1980, declining thereafter with only weak sensitivity to the Representative Concentration Pathway (RCP). One model, however, projects approximately stable RF levels, while two show increasingly negative RF due to nitrate (not included in most models). Aerosol ERF, in contrast, becomes more negative during 1980 to 2000. During this period, increased Asian emissions appear to have a larger impact on aerosol ERF than European and North American decreases due to their being upwind of the large, relatively pristine Pacific Ocean. There is no clear relationship between historical aerosol ERF and climate sensitivity in the CMIP5 subset of ACCMIP models. In the ACCMIP/CMIP5 models, historical aerosol ERF of about -0.8 to -1.5 Wm(-2) is most consistent with observed historical warming. Aerosol ERF masks a large portion of greenhouse forcing during the late 20th and early 21st century at the global scale. Regionally, aerosol ERF is so large that net forcing is negative over most industrialized and biomass burning regions through 1980, but remains strongly negative only over east and southeast Asia by 2000. Net forcing is strongly positive by 1980 over most deserts, the Arctic, Australia, and most tropical oceans. Both the magnitude of and area covered by positive forcing expand steadily thereafter.