Interaction of Large Scale Zonal Flow Anomalies and Topography
Abstract
Relatively long-term fluctuations are evident in the low level circulations surrounding the Andes and the Rocky Mountains. Some of these fluctuations are commonly explained by local, thermal influences that characterize monsoons as well as by regional responses to remote, tropical forcings. This study - first explores the seasonal cycle of low level circulations in the vicinity of the Andes and compares it to other mountainous regions such as the Rockies and the Tibetan plateau. Pronounced mechanical flow modifications appear to be associated with orographic deflection over both the Andes and the Rockies. Reanalysis diagnostics, and medium range and month-long integrations of the Utah Global Model (UGM) are presented. Analyses of orographically forced, stationary Rossby waves suggest that climatological, annual and interannual variations observed around the largest mountain ranges may be explained in terms of mechanical, orographic flow deflection. Over South America, this effect tends to produce an orographic ally bound cyclone in all seasons, with a poleward low-level jet (LLJ) east of the Andes.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 2004
- Accession Number
- ADA425035
Entities
People
- Lee A. Byerle
Organizations
- Air Force Institute of Technology