A note on boundary-layer friction in baroclinic cyclones

Dissipative-centrifugal instability of the Burgers vortex core and cyclone-anticyclone vortex asymmetry

A new exact solution of the hydrodynamic equations is obtained in the form of the Burgers vortex generalization (BVG)accounting for the medium rotation as a whole and linear uniform friction. The nonlinear dissipative-centrifugal instability(DCI)condition, associated with some superthreshold rotation angular velocity and nonzero friction, for solid-body rotating core of BVG is obtained. The new effect of cyclone-anticyclone vortex asymmetry, arising during DCI of BVG vortex core, is shown to be similar to that observed for the atmospheres of high speed rotating planets and laboratory experimen…

Acceleration of Tropical Cyclones As a Proxy For Extratropical Interactions: Synoptic-Scale Patterns and Long-Term Trends

It is well known that rapid changes in tropical cyclone motion occur during interaction with extratropical waves. While the translation speed has received much attention in the published literature, acceleration has not. Using a large data sample of Atlantic tropical cyclones, we formally examine the composite synoptic-scale patterns associated with tangential and \curvature components of their acceleration. During periods of rapid tangential acceleration, the composite tropical cyclone moves poleward between an upstream trough and downstream ridge of a developing extratropical wavepacket. The…

东亚气旋活动春季峰值的机制

Mechanisms for a Spring Peak in East Asian Cyclone Activity

本研究基于大气再分析和线性斜压模型实验，揭示了东亚气旋活动春季峰值机制，发现东海气旋生成增强、低空急流及非绝热加热是关键因素。

Baroclinic Instability and Transitions in a Two-Layer Quasigeostrophic Channel Model

The main objective of this article is to derive a mathematical theory associated with the nonlinear stability and dynamic transitions of the basic shear flows associated with baroclinic instability, which plays a fundamental role in the dominant mechanism shaping the cyclones and anticyclones that dominate weather in mid-latitudes, as well as the mesoscale eddies that play various roles in oceanic dynamics and the transport of tracers. This article provides a general transition and stability theory for the two-layer quasi-geostrophic model originally derived by Pedlosky \cite{ped1970}. We show…

Basic Concepts Involved in Tropical Cyclone Boundary Layer Shocks

This paper discusses some basic concepts that arise in the study of the tropical cyclone frictional boundary layer. Part I discusses the concepts of asymptotic triangular waves and asymptotic N-waves in the context of the nonlinear advection equation and Burgers' equation. Connections are made between triangular waves and single eyewalls, and between N-waves and double eyewalls. In Part II, analytical solutions of a line-symmetric, $f$-plane, slab model of the atmospheric boundary layer are presented. The boundary layer flow is forced by a specified pressure field and initialized with $u$ and …

Ribbon Turbulence

We investigate the non-linear equilibration of a two-layer quasi-geostrophic flow in a channel forced by an imposed unstable zonal mean flow, paying particular attention to the role of bottom friction. In the limit of low bottom friction, classical theory of geostrophic turbulence predicts an inverse cascade of kinetic energy in the horizontal with condensation at the domain scale and barotropization on the vertical. By contrast, in the limit of large bottom friction, the flow is dominated by ribbons of high kinetic energy in the upper layer. These ribbons correspond to meandering jets separat…