NRL-Developed NEPTUNE Advances Navy Weather Prediction from Global to Tactical Scales

NRL-Developed NEPTUNE Advances Navy Weather Prediction from Global to Tactical Scales

By Jameson Crabtree, U.S. Naval Research Laboratory

Washington D.C. - The U.S. Naval Research Laboratory-developed Navy Environmental Prediction sysTem Utilizing a Nonhydrostatic Engine, known as NEPTUNE, is poised to become an operational Navy weather prediction capability, providing improved environmental forecasts to support naval operations around the globe.

Developed for over a decade, NEPTUNE is designed to modernize and ultimately unify the Navy's atmospheric modeling capabilities, providing a common prediction system capable of representing weather phenomena from the global scale down to high-resolution tactical environments.

"NEPTUNE provides improved global and tactical-scale environmental characterization for the warfighter over the existing systems," said Alex Reinecke, Ph.D., NRL meteorologist and NEPTUNE project lead.

The Navy currently relies on separate atmospheric models for different forecasting requirements. The Navy Global Environmental Model, or NAVGEM, provides global atmospheric prediction, while the Coupled Ocean/Atmosphere Mesoscale Prediction System, or COAMPS, provides higher-resolution regional forecasts. A specialized version, COAMPS-TC, supports tropical cyclone prediction.

NEPTUNE establishes a common modeling framework capable of addressing those different scales while improving computational efficiency. The architecture allows the model to take advantage of increasingly powerful high-performance computing systems, enabling higher-fidelity predictions to be produced more efficiently.

The first operational implementation of NEPTUNE will replace the Navy's existing global atmospheric prediction system. Transition of regional and tactical-scale capabilities is planned separately as the Navy moves toward the broader unified modeling framework.

For Sailors and Navy forecasters, the transition brings improvements in several areas of atmospheric prediction. Extended testing and validation demonstrated improvements in low-level temperature, moisture and wind forecasts, particularly over the open ocean, along with improved tropical precipitation and cloud prediction.

NEPTUNE also provides the capability to resolve atmospheric phenomena at higher spatial resolutions than the Navy's existing global model, opening the door to representing smaller-scale weather features such as thunderstorms.

The capability is transitioning to the Fleet Numerical Meteorology and Oceanography Center, or FNMOC, in Monterey, California, which provides worldwide meteorological and oceanographic products to Navy operational forces.

NRL transitioned NEPTUNE to FNMOC in January 2025 and has worked closely with the center as the system progressed toward full operational implementation. Once operational, NEPTUNE-generated global products will be made available to Navy forecasters and distributed to the fleet as part of a phased implementation.

"This was a tremendous team effort that brought together scientists, developers and operational partners over many years," Reinecke said. "Taking NEPTUNE from an emerging research capability to a system ready to support Navy operations has been an incredibly rewarding experience, and it demonstrates what sustained collaboration can accomplish."

Reinecke began working on NEPTUNE around 2015 and eventually led a multidisciplinary team of a dozen federal scientists and a similar number of contractors responsible for designing, testing and implementing the system.

The effort advanced through multiple stages of basic and applied research before receiving additional support from the Oceanography and Navigation branch within the United States Navy's Chief of Naval Operations staff and the Office of Naval Research for accelerated development and transition. That progression represents a central NRL mission: moving scientific research from the laboratory into operational capabilities for the Navy and Marine Corps.

Beyond the initial global implementation, NEPTUNE's architecture creates opportunities for capabilities that extend far above conventional weather forecasting.
Current atmospheric prediction systems typically extend 70 to 100 kilometers above Earth, depending on the configuration. A deep-atmosphere version of NEPTUNE is being developed to extend the model to 500 kilometers, enabling the neutral atmosphere to be coupled with ionospheric prediction.

The planned capability would couple NEPTUNE with the Navy's ionospheric modeling capability, creating what Reinecke described as the first coupled neutral-atmosphere and ionosphere prediction system of its kind.

The broader vision is a Navy environmental prediction architecture that can follow atmospheric processes across scales rather than relying on separate modeling systems for individual forecasting requirements.

For NRL, NEPTUNE also represents the culmination of years of research, software development, validation and collaboration required to move a scientific concept toward operational use.

"NEPTUNE is more than the transition of a new weather model," Reinecke said. "It establishes a foundation we can continue to build on, from improving global and tactical-scale forecasts today to expanding environmental prediction farther into the upper atmosphere in the future. That gives the Navy a path toward a more integrated understanding of the environment in which it operates."

As NEPTUNE moves into operations, that work will provide Navy forecasters with a new generation of global atmospheric prediction while establishing the foundation for future tactical and upper-atmospheric capabilities.

About the U.S. Naval Research Laboratory

NRL is a scientific and engineering command dedicated to research that drives innovative advances for the U.S. Navy and Marine Corps from the seafloor to space and in the information domain. NRL is located in Washington, D.C. with major field sites in Stennis Space Center, Mississippi; Key West, Florida; Monterey, California.

NRL offers several mechanisms for collaborating with the broader scientific community, within and outside of the Federal government. These include Cooperative Research and Development Agreements (CRADAs), LP-CRADAs, Educational Partnership Agreements, agreements under the authority of 10 USC 4892, licensing agreements, FAR contracts, and other applicable agreements.

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