image: The graph displays the tropical cyclone (TC) track error comparison in nautical miles (nmi) for summer/fall 2012. The NAVGEM TC track error is 30 nmi less than NOGAPS, approximately a 12-hour improvement. Synoptic evaluations of daily weather maps show reduced surface pressure errors with NAVGEM, particularly for maritime lows that impact the safety of ships at sea. view more
Credit: US Naval Research Laboratory
WASHINGTON--The U.S. Naval Research Laboratory (NRL) Marine Meteorology Division and Space Science Division have been awarded the Department of the Navy Acquisition Excellence Technology Transition Award presented by Assistant Secretary of the Navy for Research, Development and Acquisition, Sean J. Stackley, May 14, 2013.
Recognizing individuals and teams for outstanding contributions in promoting competition and innovation in the Navy and Marine Corps acquisition process, the NRL team receives the award for a new generation atmospheric global prediction system.
The Navy Global Environmental Model (NAVGEM) is a high-resolution global weather prediction system representing a significant milestone in Numerical Weather Prediction (NWP) system development introducing a semi-Lagrangian/semi-implicit (SL/SI) dynamical core with advanced moisture and ozone physical parameterization schemes.
"The greatest improvement is in the use of this new SL/SI method that enables the high-resolution needed for modern NWP systems while it still meets the operational scheduling requirement '" said Dr. Melinda Peng, head, Atmospheric Dynamics and Prediction Branch and NAVGEM team lead. "This results in the most significant Navy global numerical weather prediction advancement over the past 20 years."
The SL method is to find the trajectory of the fluid motion that starts at the previous time step and ends up at the NAVGEM grid point location. The SL integration removes the Courant-Friedrichs-Lewy (CFL) limitation, required in the Navy Operational Global Atmospheric Prediction System (NOGAPS), using the conventional Eulerian integration of the dynamical equations. The remaining issue of high-speed gravity waves in the wind divergence is mitigated by incorporating a SI method into the SL integration, where the terms responsible for the gravity waves are identified and treated in an implicit manner and rendering small time steps unnecessary.
Replacing the existing NOGAPS, introduced in 1982, NAVGEM allows for much higher model resolutions and excludes the need for small time steps (Currently, NAVGEM allows for 50 vertical levels in place of the 42 levels in NOGAPS and an increase of horizontal resolution from 42 kilometers to 37 kilometers.) to include cloud liquid water, cloud ice water, and ozone as fully predicted constituents.
NAVGEM contains new moisture, solar radiation and longwave-radiation parameterizations and upgrad1es to the data assimilation component to complete the 180-hour forecast in the allotted operation window.
NAVGEM was delivered to the Fleet Numerical Meteorology and Oceanography Center (FNMOC) on September 30, 2012, and entered official operation in March 2013. NAVGEM is part of the global modeling 'bridging strategy' where the Navy and the National Weather Service (NWS) jointly develop a national global forecasting system named Earth System Prediction Capability (ESPC) that will be fielded in the 2020 timeframe.
The Office of Naval Research (ONR), Oceanographer of the Navy (OPNAV N2N6E) and Department of the Navy for Research, Development and Acquisition Program Executive Officer (PEO-C4I/PMW-120) provided funding for NAVGEM development.