标题： 使用大涡模拟研究气候变化如何影响气溶胶-云相互作用 显示英文标题

标题： Using Large Eddy Simulations to Study How Climate Change Influences Aerosol-Cloud Interactions

摘要： 由于气溶胶-云相互作用是地球系统中最具不确定性的气候强迫因素，因此更好地理解气溶胶-云相互作用非常重要，尤其是它们将如何随着气候的变化而变化。本研究对东北太平洋海洋上沿气团轨迹进行的3天层积云到积云转变（SCT）进行了大涡模拟（LES）。通过在SCT模拟中的海洋边界层（MBL）内扰动气溶胶浓度，我们评估了当前气候以及双二氧化碳气候下的气溶胶-云相互作用。我们发现，气溶胶引起的云变化，包括云量和液态水路径（LWP）的第一（Twomey效应）和第二调整的间接效应，会在双二氧化碳气候下受到抑制。LWP调整比Twomey效应对全球变暖更敏感。通过对气溶胶引起的云辐射效应变化（$\Delta$CRE）进行分解，我们发现气溶胶引起的云量变化（$\Delta$CF）在我们的模拟中对$\Delta$CRE贡献最大。气溶胶引起的液滴数浓度变化（$\Delta$Nc）表现出冷却效应，而LWP变化则表现出与气溶胶引起的云变薄一致的升温效应。总体而言，在双二氧化碳气候下，与气溶胶浓度增加相关的冷却效应将减弱。我们的结果还可以帮助理解和预测在气候变化中海洋云增亮（MCB）的冷却潜力。 显示英文摘要

摘要： Because aerosol-cloud interactions are the most uncertain climate forcing in the Earth system, it is important to better understand the aerosol-cloud interactions, especially how they will change with climate. This study carries out large eddy simulations (LES) of a 3-day stratocumulus-to-cumulus transition (SCT) along an airmass-following trajectory in the Northeast Pacific Ocean. By perturbing aerosol concentrations within the marine boundary layer (MBL) in the SCT simulations, we evaluate aerosol-cloud interactions in both the present day as well as in a double-CO2 climate. We find that aerosol-induced cloud changes, including first (Twomey effect) and second adjustments of cloud fraction and liquid water path (LWP) indirect effects of aerosols, tend to be inhibited in a double-CO2 climate. The LWP adjustment is more sensitive to global warming than the Twomey effect. By decomposing the aerosol-induced cloud radiative effect change ($\Delta$CRE), we find that the aerosol-induced cloud fraction change ($\Delta$CF) shows the largest contribution to $\Delta$CRE in our simulations. Aerosol-induced droplet number concentration change ($\Delta$Nc) shows a cooling effect, while the LWP change shows a warming effect that is consistent with aerosol-induced cloud thinning. Overall, the cooling effect associated with increased aerosol concentrations will weaken in a double-CO2 climate. Our results can also help to understand and predict the cooling potential of marine cloud brightening (MCB) in a changing climate.