Simulation of Typhoon Rammasun using COAMPS-TC

Actual vs Predicted Storm Path

Principle Investigator: Dr. James D. Doyle (NRL-Monterey), Dr. Richard Hodur (SAIC), Dr. Jon Moskaitis (NRL-Monterey)
HPC System: Navy DSRC IBM iDataPlex (Haise)
Sponsor: Navy Research Laboratory (NRL)


Typhoon Rammasun Path Prediction

Background Details:

The demand for more accurate forecasts of tropical cyclone track and intensity with longer lead times is greater than ever due to the enormous economic and societal impact. A dramatic example occurred during October 2012 as Hurricane Sandy threatened many communities along the U.S. Eastern Seaboard. Basic questions such as where Sandy would track and how strong it would become had profound implications for the millions of people in its path and billions of dollars of vulnerable assets. The decision to sortie Navy assets from Norfolk, VA and other ports along the eastern seaboard days in advance of the storm was critically dependent on forecasts of Sandy's track, intensity (maximum sustained wind speed at the surface), and storm structure (such as the size of the storm or radius of key wind speed thresholds). In the Western North Pacific basin, which is an area of strategic importance for the U.S. Navy, the Navy Pacific Fleet is often impacted by significant and sometimes unpredictable typhoons. Tropical cyclones remain the most disruptive and devastating environmental threat impacting Fleet operations.

There has been remarkable improvement of tropical cyclone (TC) track prediction through the use of global prediction models. However, intensity prediction remains a significant challenge and progress has been considerably slower. The slow improvement in TC intensity and structure forecasts has been attributed to a variety of reasons ranging from a lack of critical observations in the TC inner core and the surrounding environment to inaccurate representations of physical processes in numerical weather prediction (NWP) models. Advances in high-resolution TC modeling and data assimilation are thought to be necessary in order to significantly improve the intensity and structure prediction. To this end, the Naval Research Laboratory (NRL) in Monterey, CA, has developed the Coupled Ocean/Atmosphere Mesoscale Prediction System for Tropical Cyclones (COAMPS-TC), a new version of COAMPS designed specifically for high-resolution tropical cyclone prediction.

Simulation Details:

The COAMPS-TC model builds on the existing infrastructure of COAMPS and provides the framework to add new capabilities and advancements in the data assimilation, vortex initialization, physical parameterization, and air-sea coupling appropriate for high-resolution tropical cyclone prediction. The atmospheric module within COAMPS-TC is coupled to the Navy Coastal Ocean Model (NCOM) to represent air-ocean interaction processes. Simulations of Typhoon Rammasun have been conducted using a 45 km, 15 km and 5 km nested version of COAMPS-TC, with the inner two meshes following the storm. Typhoon Rammasun was one of only two Category 5 super typhoons on record in the South China Sea, with the other, Pamela, occurring in 1954. Rammasun had destructive impacts across the Philippines, South China, and Vietnam in July 2014. Here we simulate Rammasun using COAMPS-TC initialized at 0000 UTC 14 July 2014. COAMPS-TC was run for a 5 day forecast using global model forecast lateral boundary conditions for the outer grid mesh. COAMPS-TC was run on the Navy DSRC IBM iDataPlex (Haise) using 240 processors.

Visualization Details:

To achieve the animation, a sphere object is created in 3D Studio Max and textured with the topography of Earth. The coordinates of the COAMPS-TC predicted storm location and actual storm location at each data point are imported into 3D Studio Max, as latitude and longitude, and mapped to the sphere. Synchronization of time, text, and other enhancements are handled through Adobe After Effects after the individual image sequences are rendered from 3D Studio Max.

The first scene depicts the actual path of the storm accompanied by satellite imagery of the cloud cover at each data point; the cloud data is publicly available from NASA. The second scene shows a direct comparison between the COAMPS-TC prediction and the actual path taken by the storm.

A second movie, with many more details, was also produced; however the data contained within is not available for public release so it cannot be posted here.