An Energetic View on the Geographical Dependence of the Fast Aerosol Radiative Effects on Precipitation
An Energetic View on the Geographical Dependence of the Fast Aerosol Radiative Effects on Precipitation
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关于快速气溶胶辐射对降水影响的地理依赖性的能量观点
DOI：
10.1029/2020jd033045
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
G. Dagan;P. Stier;D. Watson‐Parris
中科院分区：
文献类型：
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作者：
G. Dagan;P. Stier;D. Watson‐Parris
通过与辐射相互作用，气溶胶扰乱了地球的能量收支，从而影响了全球降水量。以前的研究表明，气溶胶-辐射相互作用导致全球平均降水量减少。我们在水行星模拟中进一步证明了热带和热带以外地区对吸收气溶胶的局部反应不同。在这项研究中，我们纳入了能量收支的观点，以进一步研究理想化的全球模拟中气溶胶辐射相互作用对降水影响的纬度依赖性。我们证明了热带地区正的局部降水响应和热带以外地区负的局部降水响应之间的过渡发生在相对低的纬度（10°），表明深热带地区之间的过渡（其中科里奥利力低，因此直接热驱动循环，以及能量/水分的相关发散/会聚，可以作为非绝热加热的结果形成）及其周围环境。此外，我们逐渐增加模拟的复杂程度，并证明，在吸收气溶胶的情况下，由于表面潜热通量的减少，陆地的影响是抵消深热带内外的一些响应，这与非绝热加热相反。散射气溶胶的影响也进行了检查，并证明在热带和热带以外的陆地上的降水减少，而在海洋上没有影响。最后，我们在一个更现实的设置中检查这些结果，并证明，尽管物理机制仍然起作用，但它们不足以从模型的自然变异性中辨别出来。
By interacting with radiation, aerosols perturb the Earth’s energy budget and thus the global precipitation amount. It was previously shown that aerosol‐radiation interactions lead to a reduction in the global‐mean precipitation amount. We have further demonstrated in aqua‐planet simulations that the local response to absorbing aerosols differs between the tropics and the extra‐tropics. In this study we incorporate an energy budget perspective to further examine the latitudinal‐dependence of the effect of aerosol‐radiation interaction on precipitation in idealized global simulations. We demonstrate that the transition between a positive local precipitation response in the tropics and a negative local precipitation response in the extra‐tropics occurs at relatively low latitudes (∼10°), indicating a transition between the deep‐tropics (in which the Coriolis force is low, hence direct thermally driven circulation, and associated divergence/convergence of energy/moisture, can form as a result of the diabatic‐heating) and their surroundings. In addition, we gradually increase the level of complexity of the simulations and demonstrate that, in the case of absorbing aerosols, the effect of land is to counteract some of the response both inside and outside the deep‐tropics due to the reduction in surface latent‐heat flux that opposes the diabatic‐heating. The effect of scattering aerosols is also examined and demonstrates a decrease in precipitation over land in both the tropics and extra‐tropics and no effect over the ocean. Finally, we examine these results in a more realistic set‐up and demonstrate that, although the physical mechanisms still operate, they are not significant enough to be discerned from the model’s natural‐variability.