Numerical weather prediction (NWP) systems issue forecasts with finite spatial resolution and limited vertical range. For example, the Navy Global Environmental Model (NAVGEM) provides global forecasts with a horizontal resolution of ~50-100 km, whereas the Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS®) provides nested regional forecasts of much higher spatial resolution. Both NWP systems currently extend to ~40 km altitude, operationally forecasting only the troposphere and the lower part of the stratosphere. NRL is developing high-altitude prototypes of both systems that extend the vertical range to ~100 km altitude to encompass the “near-space” environment (stratosphere and mesosphere). The 4DVAR-based data assimilation capabilities of both NWP systems facilitate new adjoint- and ensemble-based predictability tools that permit state-of-the-art quantitative examination of the fundamental predictability of near-space dynamics at small and large scales, and their specific sensitivities to features in the flow or to perturbations and uncertainties in atmospheric initial conditions. We seek applicants to collaborate with us in applying these high-altitude NWP systems and their associated predictability tools to research the multiscale predictability of the near-space environment and the coupling between altitudes and spatial scales. Since the global climate and meteorology of the near space are so strongly driven by breaking upward-propagating small-scale gravity waves generated in the troposphere, a major focus of this work will be gravity-wave predictability. We will use high-resolution COAMPS ensemble and adjoint simulations to study the predictability of gravity waves forced by flow over mountain ranges and from jet streams, both near the tropospheric source and at stratospheric and mesospheric altitudes where these waves subsequently propagate and dissipate. For example, we will investigate recent suggestions that certain flow regimes, such as low Froude number flow over extended high ridge-like mountains, can exhibit appreciable ensemble spread. This research will in turn inform development of better subgrid-scale parameterizations of near-space gravity wave drag for NAVGEM, such as nonlocal stochastic schemes with explicit inbuilt variability, and is also finding applications in planetary atmospheric research on Mars. It will also improve new global forecasting algorithms of wave-induced stratospheric clear-air turbulence due to gravity wave breaking, such as COAMPS and NRL’s Mountain Wave Forecast Model (MWFM), which are needed as decision aids for near-space DoD assets such as U-2s, high-altitude airships, theater high-altitude area defense, and the Global Hawk fleets performing the Navy’s Broad Area Maritime Surveillance (BAMS). For more information, go to our web site at http://uap-www.nrl.navy.mil/uap/?content=section;code=7646.

 

key words

Weather forecast; Stratosphere; Mesosphere; Near space; Adjoint; Ensembles; Predictability; Singular vectors; Middle atmosphere; High-performance computing; Gravity waves; Turbulence;

Citizenship:  Open to U.S. citizens and permanent residents

Level:  Open to Postdoctoral applicants