Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming
Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming
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DOI：
10.1175/jcli-d-12-00655.1
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发表时间：
2013-07-01
影响因子：
4.9
通讯作者：
Muller, Caroline
中科院分区：
文献类型：
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作者：
Muller, Caroline
在这项研究中，热带降水极端有组织的对流变暖的反应进行了检查，使用云解析模式。垂直切变的作用使对流组织成飑线。早期的研究表明，在无组织对流中，降水极端值的增加比例与地面水汽的增加比例相似，远小于柱水汽的增加。有人建议，有组织的对流可能会导致更强的amplification.No的强度的剪切，放大的降水极端云解析模拟是可比的地面水蒸气和大大低于柱水汽的增加。结果无切变和临界切变，其中的飑线是垂直于切变，是令人惊讶的相似，降水极值的增长率比地面水蒸气的增长率稍小。有趣的是，切变对降水的影响是非单调的，且超临界切变越强，降水的变化率越大，接近或略大于地面湿度。到一阶，它们是由热力学分量，它具有相同的幅度为所有剪切，接近地表水蒸气的变化占主导地位。动态贡献起次要作用，并倾向于削弱极端没有剪切和临界剪切，而它加强极端与超临界剪切。这些不同的动力学贡献不同的切变是由于不同的响应的对流质量通量在个别上升气流变暖。
In this study the response of tropical precipitation extremes to warming in organized convection is examined using a cloud-resolving model. Vertical shear is imposed to organize the convection into squall lines. Earlier studies show that in disorganized convection, the fractional increase of precipitation extremes is similar to that of surface water vapor, which is substantially smaller than the increase in column water vapor. It has been suggested that organized convection could lead to stronger amplifications.Regardless of the strength of the shear, amplifications of precipitation extremes in the cloud-resolving simulations are comparable to those of surface water vapor and are substantially less than increases in column water vapor. The results without shear and with critical shear, for which the squall lines are perpendicular to the shear, are surprisingly similar with a fractional rate of increase of precipitation extremes slightly smaller than that of surface water vapor. Interestingly, the dependence on shear is nonmonotonic, and stronger supercritical shear yields larger rates, close to or slightly larger than surface humidity.A scaling is used to evaluate the thermodynamic and dynamic contributions to precipitation extreme changes. To first order, they are dominated by the thermodynamic component, which has the same magnitude for all shears, close to the change in surface water vapor. The dynamic contribution plays a secondary role and tends to weaken extremes without shear and with critical shear, while it strengthens extremes with supercritical shear. These different dynamic contributions for different shears are due to different responses of convective mass fluxes in individual updrafts to warming.