Winter 2000

Today within Environment Canada, research and computer matters such as software, hardware and person resources are strongly connected with the centre located in Dorval which houses a Meteorological Research Branch (MRB) division named Recherche en Privision Numirique (RPN), as well as the Canadian Meteorological Centre (CMC). Over recent decades, computer scientists working there have developed software and tools to facilitate both operational and research communities.

Since AEPRI is a kind of an extension of RPN in the eastern part of the country (RPNEast), it also brings with it an unavoidable entity used at RPN/CMC -- the STANDARD FILE, which is a kind of gribbed data format. Many tools have been developed around these standard files that tremendously facilitate life once one knows how to use them. From edition, modification, calculation and the display of them, there is a variety of tools and the ARMNLIB library, full of subroutines already existing and very useful. In fact, the ARMNLIB environment has already penetrated your walls and is slowly evolving to be used by various groups at Dalhousie and BIO.

With the growing collaboration and interaction between RPN/CMC and Dalhousie University, we feel that it is a good idea to present you an overview of these tools and the COUPLER used at RPN. Without covering all of them, this will first reveal to you the existence of such tools. This presentation will also give you a rough idea of how they work and their functionality, and one hopes that you will find them very useful to be extended to your own projects.

Abstract: We investigate some of the claims concerning new eddy parameterization schemes for coarse resolution ocean models by analyzing the role of eddies in eddy-resolving 1-1/2 and 2-1/2 layer models with double-gyre wind forcing. We find that the divergent part of the eddy flux of potential vorticity is directed down the mean potential vorticity gradient. The relationship between the eddy flux of thickness and either the mean thickness or potential vorticity gradients is less clear.

Also:
Poster Display: Chris Braun
Title: Tropical transition zone and the upper tropical tropospheric ozone budget

Chris will be displaying his EGS poster and will gladly entertain any questions and comments with regards to it.

We first ran the model in prognostic mode with temperature and salinity evolving freely with the flow. The model results during the first-year simulation reproduced many well-known circulation features in the study region, including the Labrador Current and North Atlantic Current and their interaction over the Newfoundland basin. The model also reproduced reasonably well the seasonal cycle of the mixed layer depth and temperature over the most areas of the study region. The model results however deteriorated gradually with model simulation, due mainly to a crude and unphysical representation of internal mixing and a relatively coarse model resolution.

To improve the model skill we developed a novel data assimilation technique. The main idea is to adjust the flow field towards climatology, while still permitting a mesoscale eddy field and still allowing the temperature and salinity fields to evolve freely with the flow. The model results produced using this technique will be presented and show a significant improvement over those produced without data assimilation.