Structures of Equatorial Envelope Rossby Wave Under a Generalized External Forcing

The cubic nonlinear Schrodinger (NLS for short) equation with a generalized external heating source is derived for large amplitude equatorial envelope Rossby wave in a shear flow. And then various periodic structures for these equatorial envelope Rossby waves are obtained with the help of a new transformation, Jacobi elliptic functions,and elliptic equation. It is shown that different types of resonant phase-locked diabatic heating play different roles in structures of equatorial envelope Rossby wave.

Periodic Structures of Rossby Wave under Influence of Dissipation

A simple barotropic potential vorticity equation with the influence of dissipation is applied to investigate the nonlinear Rossby wave in a shear flow in the tropical atmophere. By the reduetive perturbation method, we derive the rotational KdV （rKdV for short） equation. And then, with the help of Jaeobi elliptie functions, we obtain various periodic structures for these Rossby waves. It is shown that dissipation is very important for these periodic structures of rational form.

Two-Dimensional Rossby Waves： Exact Solutions to Petviashvili Equation

The two-dimensional （2D） nonlinear Rossby waves described by the Petviashvili equation, which has been invoked as an ageostrophic extension of the barotropic quasi-geostrophic potential vorticity equation, can be investigated through the exact periodic-wave solutions for the Petviashvili equation, while the exact analytical periodic-wave solutions to the Petviashvili equation are obtained by using the Jacobi elliptic function expansion method. It is shown that periodicwave 2D Rossby solutions can be obtained by this method, and in the limit cases, the 213 Rossby soliton solutions are also obtained.

THE TOPOGRAPHIC PARAMETER SENSITIVITY TO VORTICITY PROPAGATION AND TYPHOON TANGENTIAL VELOCITY CHANGES

A high resolution shallow-water model is designed to study the roles which the topographical parameter and latitudinal basic flow play in the propagation of vortex Rossby waves and typhoon tangential velocity changes. With no latitudinal flow, the horizontal scale effects of island terrain on the vortex Rossby waves propagation show that the disturbance vorticity follows a clockwise island-circulating path more significantly, the local maximum wind speed amplitude reduces more sharply, the maximum mean azimuthally tangential wind spins down more substantially, when the topographic horizontal scale augments. With the latitudinal basic flow, the evolution of local wind and mean velocity are affected by the distance changes between TC and the terrain and the time length of topographic action: the local wind amplitude intensifies and the mean velocity diminishes while the distance is shortening; the opposite is true while TC is away from the terrain gradually.

Features of the EAP events on the medium-range evolution process and the mid-and high-latitude Rossby wave activities during the Meiyu period

In this paper,features for the evolution of the East Asia/Pacific(EAP) events and their association with high-and mid-latitude Rossby waves during the Meiyu period are analyzed on the medium-range time scale.It is shown that life cycles of the positive and negative EAP events cannot be simply regarded as "mirror" each other.In the upper troposphere,downward propagations of Rossby wave packets both over high-and mid-latitude regions of Eurasian continent and over the Asian jet region are responsible for generating basic patterns of high-and mid-latitude anomaly centers of the events.In this layer,Rossby wave packets also propagate from the mid-latitude anomaly center to the high-latitude one.In the middle and lower troposphere,the formation of the subtropical anomaly center of the event is mainly attributed to the anomalous convective activity in the tropical Pacific warm pool.The northward Rossby wave energy dispersion from this center is favorable to the enhancement and maintenance of the mid-latitude anomaly center in the same layer.Finally,it might be hypothesized that typical features of the positive and negative EAP events in their mature phase result from the interaction between(or phase-locking of) respective anomalous circulations induced both by quasi-zonal Rossby wave packets embedded in upper troposphere westerly and by quasi-meridional Rossby wave packets in the background flow of the East Asian summer monsoon in the middle and lower troposphere.

Spiral rainband in a numeri-cally simulated tropical cyclone

Spiral rainband is a prominent structure of tropical cyclone. Though its forming mechanism, vortex Rossby wave theory, has been widely accepted in recent years, its internal structural features are still not well known. The spiral rainband in the severe tropical storm Kammuri (2002), which caused heavy rainfall in southeast China, is simulated using the mesoscale model MM5 (V3). Results show that the simulated spiral rainband propagates azimuthally at a speed close to that of vortex Rossby wave in theory, and is accom- panied with energy dispersion in the radial direction. The structural features of simulated spiral rainband are analyzed with the high-resolution model output including the full physical process. Positive vorticity, ascending motion, hori- zontal momentum and so on are highly concentrated in the spiral rainband. The convergent moisture of spiral rainband comes mostly from the planetary boundary layer under 1 km. Airflow from the outside of spiral rainband is convective instability, which can provide instability energy for convec- tion development. However, the atmospheric stratification in the inside of spiral rainband is neutral, implying that the instability energy has been released. There is a mesoscale strong wind band just near the spiral rainband in the outer side with a maximum wind speed exceeding 30 m/s, which results from the pressure force acceleration when the air flows into the spiral rainband along the gradient of pressure.