Using Potential Vorticity to Characterize the Forcing of a Coastally Trapped Wind Reversal Along the California Coast
Abstract
Using the Climate Forecast System Reanalysis (CFSR) dataset, the synoptic environment of six historical coastally trapped wind reversals (CTWR) along the California coast is examined. Building on the Mass and Bond climatology of 1996, the study uses potential vorticity (PV) as a proxy for the coastal jet and seeks to characterize the forcing of the CTWRs by analyzing their 950-mb potential vorticity plumes. The study also pursues the ability to separate geostrophically-balanced wind reversals synonymous with synoptic systems from unbalanced wind reversals (CTWRs) by taking advantage of the invertibility of PV and using the inversion technique outlined in the August 1991 issue of Monthly Weather Review by Christopher Davis and Kerry Emanuel. The study then applied the methodology to data from July/August 2012/2013 in order to uncover possible CTWRs. The primary findings of this study are as follows: 1) the potential vorticity maximum generated through the offshore flow of the coastal jet is required to move off shore and establish an across-coast PV gradient in order for a CTWR to form/propagate northward of Point Conception and 2) the Davis Emanuel PV inversion technique yielded mixed results, heavily influenced by diurnal effects and subjected to instability due to topographical interactions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 2015
- Accession Number
- ADA620674
Entities
People
- Christopher M. Morris
Organizations
- Naval Postgraduate School