Validation Test Report: Coupled Ocean/Atmosphere Mesoscale Prediction System - Tropical Cyclone Ensemble (COAMPS-TC Ensemble) v2023
Abstract
Here, we describe the v2023 COAMPS-TC ensemble, which has transitioned to Fleet Numerical Meteorology and Oceanography Center and has replaced the v2021 COAMPS-TC ensemble in operations as of 5 July 2023. The v2023 COAMPS-TC ensemble is a relatively minor upgrade encompassing one important change to the model code that improves forecast performance, as well as an expanded graphics suite used to display ensemble forecasts. The change to the model consists of increasing the storm-following inner nest blend zone width (for both the 12-km grid spacing nest 2 and the 4-km grid spacing nest 3) to 18 points. Here, we show, using the ensemble control member tested over 399 retrospective forecast cases, that this inner nest blend zone expansion improves wind radii prediction and forecasts of rapid intensification (RI) without meaningful degradation to track or intensity forecasts. The larger grid 3 blend zone serves both to inhibit convection on the outskirts of the storm and to import relatively dry air from grid 2, causing tropical cyclones to be smaller and seemingly more amenable to RI. The updated graphical forecast product suite includes a new plot for minimum sea-level pressure (MSLP) and two new types of plots for the radius of 34-kt winds (R34), radius of 50-kt winds (R50), and radius of 64-kt winds (R64).
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 04, 2024
- Accession Number
- AD1223133
Entities
People
- Carey Dickerman
- James D. Doyle
- Jeremy Sousa
- Jonathan Moskaitis
- Roger Stocker
- William A. Komaromi
Organizations
- United States Naval Research Laboratory