Observational Constraints on the Cloud Thermodynamic Phase in Midlatitude Storms
Observational Constraints on the Cloud Thermodynamic Phase in Midlatitude Storms
复制标题
中纬度风暴云热力学阶段的观测约束
DOI：
10.1175/jcli3919.1
复制
发表时间：
2006
影响因子：
4.9
通讯作者：
M. Bauer
中科院分区：
文献类型：
--
作者：
C. Naud;A. Genio;M. Bauer
在云的混合相区域中，过冷液态水逐渐让位于冰的条件仍然知之甚少，可能是大气环流模式预测长期气候变化时云反馈不确定性的一个重要来源。两个冬天的云相歧视，云顶温度，海面温度，降水从几个卫星数据集（美国宇航局的Terra和Aqua中分辨率成像光谱仪，和热带降雨测量任务使命）为北大西洋和太平洋盆地进行了分析，以更好地了解这些过程。再分析表面压力和垂直速度与天气风暴跟踪算法相结合，以定义风暴轨迹，创建复合风暴动力学和云模式，并检查风暴特征在其生命周期中的变化。在大西洋和太平洋以及每个海洋盆地的东西两侧存在着不同的风暴云模式。这似乎与这两个洋盆海表温度的不同空间模式有关。冰川作用发生在非常温暖的温度下，在锋面上升区典型的高，厚，降水量大的云层中，除了垂直速度最强的地方，类似于以前的实地实验。然而，在锋面区域之外，云层较浅，过冷水存在于较低的云顶温度。这项分析是第一次大规模评估云相及其与气候代表性时间尺度动力学的关系。它提供了一个潜在的强有力的基准的设计和评估的混合相过程参数化的大气环流模式，并表明，在一些现有的模型中所作的假设可能会产生负面影响的云反馈估计。
The conditions under which supercooled liquid water gradually gives way to ice in the mixed-phase regions of clouds are still poorly understood and may be an important source of cloud feedback uncertainty in general circulation model projections of long-term climate change. Two winters of cloud phase discrimination, cloud-top temperature, sea surface temperature, and precipitation from several satellite datasets (the NASA Terra and Aqua Moderate Resolution Imaging Spectroradiometer, and the Tropical Rainfall Measuring Mission) for the North Atlantic and Pacific Ocean basins are analyzed to better understand these processes. Reanalysis surface pressures and vertical velocities are used in combination with a synoptic storm-tracking algorithm to define storm tracks, create composite storm dynamical and cloud patterns, and examine changes in storm characteristics over their life cycles. Characteristically different storm cloud patterns exist in the Atlantic and Pacific and on the west and east sides of each ocean basin. This appears to be related to the different spatial patterns of sea surface temperature in the two ocean basins. Glaciation occurs at very warm temperatures in the high, thick, heavily precipitating clouds typical of frontal ascent regions, except where vertical velocities are strongest, similar to previous field experiments. Outside frontal regions, however, where clouds are shallower, supercooled water exists at lower cloud-top temperatures. This analysis is the first large-scale assessment of cloud phase and its relation to dynamics on climatologically representative time scales. It provides a potentially powerful benchmark for the design and evaluation of mixed-phase process parameterizations in general circulation models and suggests that assumptions made in some existing models may negatively bias their cloud feedback estimates.