Connections between potential vorticity intrusions and convection in the eastern tropical pacific
Connections between potential vorticity intrusions and convection in the eastern tropical pacific
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DOI：
10.1175/2007jas2248.1
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发表时间：
2008-03-01
影响因子：
3.1
通讯作者：
Waugh, Darryn W.
中科院分区：
文献类型：
--
作者：
Funatsu, Beatriz M.;Waugh, Darryn W.
本文采用数据分析、位涡（PV）反演和数值模拟相结合的方法，研究了平流层空气进入对流层上层与热带东太平洋深层对流之间的联系。NCEP-NCAR再分析和入侵事件期间发射长波辐射的卫星测量结果表明，高PV入侵舌前缘的云量增加、静态稳定性降低、向上运动和对流有效势能（CAPE）的积累。势反演计算表明，上层PV对表征对流的量的变化做出了主要贡献。这支持了这样一种假设，即高层PV异常通过破坏对流层下层的稳定并导致PV舌区前方的上升运动来启动和支持对流。利用第五代宾夕法尼亚州立大学- ncar中尺度模式（MM5）进行的模拟证实了高空PV的主导作用。在模拟中，只有当上层PV异常存在时，对流才会发生，并且上层PV对表征对流的量变化的相对贡献与从PV反演计算中推断出的相似。
The connections between intrusions of stratospheric air into the upper troposphere and deep convection in the tropical eastern Pacific are examined using a combination of data analysis, potential vorticity (PV) inversion, and numerical simulations. Analysis of NCEP-NCAR reanalyses and satellite measurements of outgoing longwave radiation during intrusion events shows increased cloudiness, lower static stability, upward motion, and a buildup of convective available potential energy (CAPE) at the leading edge of the intruding tongue of high PV. Potential inversion inversion calculations show that the upper-level PV makes the dominant contribution to the changes in the quantities that characterize convection. This supports the hypothesis that upper-level PV anomalies initiate and support convection by destabilizing the lower troposphere and causing upward motion ahead on the PV tongue. The dominant role of the upper-level PV is confirmed by simulations using the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5). Convection only occurs when the upper-level PV anomaly is present in the simulations, and the relative contribution of the upper-level PV to changes in the quantities that characterize convection is similar to that inferred from the PV inversion calculations.