Cold pools observed during EUREC4A: detection and characterization from atmospheric soundings
Cold pools observed during EUREC4A: detection and characterization from atmospheric soundings
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EUREC4A 期间观测到的冷池：大气探测的检测和表征
DOI：
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发表时间：
2022
影响因子：
3
通讯作者：
N. Rochetin
中科院分区：
文献类型：
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作者：
L. Touzé‐Peiffer;R. Vogel;N. Rochetin
开发了一种新方法来检测热带海洋上空大气探测的冷池，并将其应用于2020年1月至2月在巴巴多斯南部和东部进行的EUREC4A实地活动的探测数据。所提出的方法使用测深区分冷池从他们的周围环境：冷池被定义为混合层高度小于400米的区域。该方法首先测试对二维表面温度和降水场在一个现实的高分辨率模拟在热带大西洋西部。然后，该方法被应用到1068大气剖面的数据集从投下式探空仪（从两架飞机发射）和1105从无线电探空仪（从一个阵列的四艘船和巴巴多斯云天文台发射）。我们发现，7%的EUREC4A探测落入冷池。冷池探测结果与i）中尺度云弧，ii）与环境相比温度下降了101 K，湿度增加了101 g kg−1相吻合。此外，冷池水分廓线表现出一个“湿层”接近地面，由“干层”，直到云底水平，其次是另一个潮湿的云层。在存在风切变的情况下，冷池的扩展有利于下切，这表明不饱和下沉气流的向下动量输送。结果支持我们的检测方法在不同的环境条件下的鲁棒性，其简单性使该方法成为表征冷池（包括其垂直结构）的有前途的工具。讨论了该方法对其它地区和对流系统的适用性
A new method is developed to detect cold pools from atmospheric soundings over tropical oceans and applied to sounding data from the EUREC4A field campaign, which took place south and east of Barbados in January-February 2020. The proposed method uses soundings to discriminate cold pools from their surroundings: cold pools are defined as regions where the mixed-layer height is smaller than 400 m. The method is first tested against 2D surface temperature and precipitation fields in a realistic high-resolution simulation over the western tropical Atlantic. Then, the method is applied to a data set of 1068 atmospheric profiles from dropsondes (launched from two aircrafts) and 1105 from radiosondes (launched from an array of four ships and the Barbados Cloud Observatory). We show that 7 % of the EUREC4A soundings fell into cold pools. Cold pools soundings coincide with i) mesoscale cloud arcs, ii) temperature drops of ∼ 1 K compared to the environment and moisture increases of ∼ 1 g kg−1. Furthermore, cold pool moisture profiles exhibit a “moist layer” close to the surface, topped by a “dry layer” until the cloud base level, and followed by another moist layer in the cloud layer. In the presence of wind shear, the spreading of cold pools is favored downshear, suggesting downward momentum transport by unsaturated downdrafts. The results support the robustness of our detection method in diverse environmental conditions and its simplicity makes the method a promising tool for the characterization of cold pools, including their vertical structure. The applicability of the method to other regions and convective regimes is discussed