Roles of Cloud Microphysics on Cloud Responses to Sea Surface Temperatures in Radiative‐Convective Equilibrium Experiments Using a High‐Resolution Global Nonhydrostatic Model
Roles of Cloud Microphysics on Cloud Responses to Sea Surface Temperatures in Radiative‐Convective Equilibrium Experiments Using a High‐Resolution Global Nonhydrostatic Model
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使用高分辨率全球非静水力模型的辐射对流平衡实验中云微物理对海面温度云响应的作用
DOI：
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发表时间：
2018
影响因子：
6.8
通讯作者：
M. Satoh
中科院分区：
文献类型：
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作者：
Tomoki Ohno;M. Satoh
利用一个高分辨率非静力二十面体大气模式，在辐射对流平衡位形下模拟了高云量对海表温度变化的响应。辐射-对流平衡是使用一个以地球为半径的非旋转球体和一个14 km的水平网格计算的，统一的SST为300和304 K。两种类型的云微物理方案（单和双矩体方案）和两种类型的垂直层配置（38和78层）进行了测试。在所有的模拟对中，由于静态稳定度的增加，辐射驱动的环流随着SST的增加而减弱，正如以前的研究所建议的那样。相比之下，高云量在三个模拟对中增加，在一个模拟对中减少。这表明，随着SST的增加，辐射驱动环流的减弱并不总是伴随着高云量的减少。我们确定，对流层顶层是湿（干）的模拟，显示积极的（消极的）高云量响应。在高云量响应为正的模拟对中，湿对流层顶正下方的辐射驱动的向上水汽输送随着SST的增加而增加，这导致了冰凝结物通过沉降过程向低层的供应，而在负响应的模拟对中没有观察到这种反馈。这表明高云量响应取决于反馈的发生，并且在各种模拟中存在反馈阈值。进而推测反馈机制的有效与否对真实的大气中的高云响应有很大的影响。
The high‐cloud amount responses to sea surface temperature (SST) changes were investigated based on simulations with radiative‐convective equilibrium configuration using a high‐resolution nonhydrostatic icosahedral atmospheric model. The radiative‐convective equilibrium was calculated using a nonrotating sphere with Earth radius and a 14‐km horizontal mesh with uniform SSTs of 300 and 304 K. Two types of cloud microphysics schemes (single‐ and double‐moment bulk schemes) and two types of vertical layer configurations (38 and 78 layers) were tested. The radiatively driven circulation weakens with increasing SST in all simulation pairs due to the increase in the static stability, as suggested in previous studies. In contrast, the high‐cloud amount increases in three simulation pairs and decreases in one pair. These indicate that the weakening of radiatively driven circulation with increasing SST does not always accompany the high‐cloud amount decrease. We determined that the tropopause layer was wet (dry) in simulations that showed positive (negative) high‐cloud cover responses. The radiatively driven upward moisture transport just below the wet tropopause layer increases with increasing SST in the simulation pairs with positive high‐cloud amount responses, and this causes the supply of ice condensate to the lower layer through the sedimentation process, while this feedback was not observed in the simulation pair with the negative response. These indicate that the high‐cloud cover response depends on the occurrence of the feedback and there is a feedback threshold among the variety of simulations. And furthermore, these speculate that whether the feedback mechanism is effective or not has the large impact on high‐cloud responses in the real atmosphere.