Genesis of an East Pacific Easterly Wave from a Panama Bight MCS: A Case Study Analysis from June 2012
Genesis of an East Pacific Easterly Wave from a Panama Bight MCS: A Case Study Analysis from June 2012
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DOI：
10.1175/jas-d-20-0032.1
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发表时间：
2020-10
影响因子：
3.1
通讯作者：
J. Whitaker;E. Maloney
中科院分区：
文献类型：
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作者：
J. Whitaker;E. Maloney
本研究研究了巴拿马湾中尺度对流系统（MCS）向成为飓风Carlotta（2012）的东风波（EW）的转变。再分析、观测和允许对流的天气研究和预报（WRF）模式模拟用于分析有助于EW形成的过程。涡度预算分析表明，对流耦合和涡旋拉伸对系统的过渡起重要作用，而水平平流对系统的传播起主要作用。模型中扰动以层状垂直运动廓线和中层涡为主，系统头重气轻，在再分析后的过渡阶段以较突出的低层涡度为特征。发展中的扰动在巴拿马湾以中尺度对流系统的形式开始演变。在MCS形成之前，Chocó急流增强，而在MCS向ew过渡期间，Papagayo急流增强。再分析系统垂直结构与模型的差异表明，再分析中相对较重的底部扰动可能与Papagayo射流的相互作用较强。在热带东太平洋对流组织（OTREC）运动期间收集的野外观测资料需要进一步了解东太平洋EW的形成途径及其影响因素，包括涡度收支背景下发展中的扰动的垂直结构的重要作用。
This study investigates the transition of a Panama Bight mesoscale convective system (MCS) into the easterly wave (EW) that became Hurricane Carlotta (2012). Reanalysis, observations, and a convective-permitting Weather Research and Forecasting (WRF) Model simulation are used to analyze the processes contributing to EW genesis. A vorticity budget analysis shows that convective coupling and vortex stretching are very important to the transition in this case, while horizontal advection is mostly responsible for the propagation of the system. In the model, the disturbance is dominated by stratiform vertical motion profiles and a midlevel vortex, while the system is less top-heavy and is characterized by more prominent low-level vorticity later in the transition in reanalysis. The developing disturbance starts its evolution as a mesoscale convective system in the Bight of Panama. Leading up to MCS formation the Chocó jet intensifies, and during the MCS-to-EW transition the Papagayo jet strengthens. Differences in the vertical structure of the system between reanalysis and the model suggest that the relatively more bottom-heavy disturbance in reanalysis may have stronger interactions with the Papagayo jet. Field observations like those collected during the Organization of Tropical East Pacific Convection (OTREC) campaign are needed to further our understanding of this east Pacific EW genesis pathway and the factors that influence it, including the important role for the vertical structure of the developing disturbances in the context of the vorticity budget.