Balanced, Potential Vorticity Dynamics in the Tropics
Abstract
A scheme for describing tropical atmospheric flow is analyzed. Based on the quasi-balanced approximation from Stevens et al. (1990), attempts are made to test the validity of the approximation. Isentropic potential vorticity, being a critical variable in the approximation, is calculated using data gathered during Phase II of the Australian Meteorological Experiment (AMEX). These isentropic potential vorticity fields are then examined in terms of the Charney-Stern theorem for instability. It is found that there is a consistent area of reversed equator-to-pole gradient of potential vorticity. This area is susceptible to combined barotropic-baroclinic instability. After reviewing several previous attempts to quantify tropical atmospheric flow, the quasi-balanced approximation from Stevens et al. (1990) is tested using archived data for several different time frames and levels in the atmosphere. It is found that the quasi-balanced approximation works very well for areas not dominated by convection. In these convective areas, however, there appears to be a weakness in the approximation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 16, 1991
- Accession Number
- ADA249981
Entities
People
- Kenneth W. Harding
Organizations
- Air Force Institute of Technology