Operational Evaluation of a Turbulence Closure Model Forecast System

Abstract

A one-dimensional turbulence model has been coupled with the large-scale fields of a hemispheric model so as to produce a high-resolution marine boundary layer forecast system. Model initialization is performed either by use of individual ship soundings or from standard fields of the hemispheric model. Detailed boundary layer forecasts in specified oceanic regions are desirable for many purposes, but large-scale model forecasts with such high resolution are computationally impractical. This paper presents results from approximately 90 different 24 h forecasts at the location of four different ocean station vessels. We statistically compare model forecast profiles of temperature and moisture with verifying soundings, and also evaluate persistence as a forecast. Results consistently show a significant improvement of the model forecasts relative to persistence. The one-way influence driving force provided by large-scale time derivative terms derived from the hemispheric model is found to be very important to this coupled forecast system.