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NOGAPS-ALPHA: A prototype high-altitude version of the Navy’s global numerical weather prediction model
Stephen Eckermann, NRL, Washington, DC; and J. P. McCormack, L. Coy, D. Allen, T. F. Hogan, Y. J. Kim, and D. E. Siskind
It is well known that the dynamics of the upper atmosphere are driven in large part by both global-scale and small-scale wave disturbances that are generated in the lower atmosphere and propagate to high altitudes. Examples include migrating and nonmigrating solar tides, Rossby normal modes, ultrafast tropical Kelvin waves, and gravity waves. Thus, space weather forecasting ideally requires a ground-to-space (G2S) global numerical weather prediction (NWP) system that can forecast the generation of this global wave field in the lower atmosphere and its subsequent penetration to higher altitudes, as modulated by intervening wind patterns in the stratosphere, mesosphere and thermosphere.
As an essential first step towards this ambitious vision, in October 2000 the Naval Research Laboratory (NRL) sponsored a 3-4 year joint research and development (R&D) project among its Space Science, Marine Meteorology and Remote Sensing Divisions to extend the global spectral forecast model (GSFM) at the core of the Navy Operational Global Atmospheric Prediction System (NOGAPS) from its current upper forecast level of ~35 km to include a prognostic stratosphere and mesosphere extending to ~100 km. NOGAPS is the Department of Defense's (DoD's) high-resolution operational global NWP system, which currently issues 6-day weather forecasts every 6 hours at T239L30 (~0.5o resolution) from the Fleet Numerical Meteorology and Oceanography Center (FNMOC). These forecasts form the backbone of the Navy’s end-to-end weather prediction capabilities.
A prototype next-generation high-altitude NOGAPS GSFM has now been developed. We refer to it as NOGAPS-ALPHA (NOGAPS with Advanced Level Physics and High Altitude). We provide a brief overview of its many new features and prognostic physical formulations for the stratosphere and mesosphere. To illustrate some of these new capabilities in action, we show results of running NOGAPS-ALPHA at both a standard T239L54 (~0-85 km) and a developmental T239L68 (~0-102 km) configuration to hindcast global meteorology from the surface to the lower thermosphere during the disturbed Southern Hemisphere winter of 2002. This period culminated in the first ever splitting of the Antarctic ozone hole in late September. We illustrate some of the interesting transitions with altitude in the hemispheric meteorology predicted by NOGAPS-ALPHA in response to this enhanced planetary wave driving from the troposphere, and show some validation for these upper-atmosphere hindcasts based on temperature data acquired by the SABER instrument on NASA’s TIMED satellite. We conclude by discussing some future developments planned for NOGAPS-ALPHA, and point out some additional issues that need to be solved before next-generation high-altitude GSFMs like NOGAPS-ALPHA are transitioned to operations at weather centers such as FNMOC.
Session 1, Aspects of Space Weather that have an element of commonality with terrestrial weather applications.
Tuesday, 11 January 2005, 8:30 AM-5:30 PM
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