Numerical prediction of marine fog using the coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS)

Abstract

The U.S. Navy's requirement for a computer prediction system for marine fog and stratus dates back to the 1970s when meteorological models were being introduced to the fleet. The Naval Research Laboratory's Coupled Ocean/ Atmosphere Mesoscale Prediction System (COAMPS) is a leap forward in the Navy's numerical modeling ability but it still does not show great skill in fog forecasting. COAMPS has been 'tuned', or adjusted for certain constants and parameterizations, so that it has the minimum error for the maximum area. This tuning is a common practice for all numerical models. The objective of this thesis is to determine if changes can be made to the existing COAMPS code based on reasonable physical experiments for a specific location to help solve the numerical fog forecasting problem. The effectiveness of these experiments was first measured by comparing a modeled cloud edge to satellite imagery of Monterey, California taken during a week in August 2000 under a variety of foggy conditions. Comparisons were also made with observations taken from an aircraft, land stations and a vertical profiler. The experiments, specifically those regarding changes to the autoconversion and turbulent kinetic energy schemes, showed that while a perfect solution has not been found, it is possible to modify the model physics codes and optimize its performance in a specific region.