During SOLVE2,
Code 7646 at
NRL is issuing forecasts of mountain wave temperature amplitudes in the
stratosphere, as well as turbulence at flight altitudes due to mountain wave
breaking (see here). These forecasts are
provided by NRL's Mountain Wave Forecast Model (MWFM),
and forecasts are being issued using both the original hydrostatic MWFM 1
model and the newer ray-based nonhydrostatic rotational MWFM 2 model.
We are currently involved in work to test a new method of
forecasting mountain wave properties using the so-called "Maslov" method. If
successful, we hope these algorithms will form the basis for a "next
generation" MWFM 3 model. This work, led by Dr. Dave Broutman, involves
numerical mountain wave solutions that combine aspects of the gravity wave
ray-tracing formalism used in MWFM 2 model with a Fourier transform solution
method for arbitrary topography commonly used in analytical solutions of
mountain wave flow problems. The method potentially offers a nice compromise
between the numerical speed and generality to arbitrary flow regimes of
numerical ray solutions and the greater realism and accuracy of wave
patterns generated by normal mode Fourier transform solutions. For more
information and background, consult the references listed below.
The forecasts issued here are sporadic and experimental. Our goal
here is to compare the output from early versions of the Maslov code during
SOLVE 2 with more operational forecast products provided by the
MWFM, 3DLOM, and
ECMWF model. Such forecast-mode comparisons,
it is hoped, will aid initial assessments of the feasibility of using a
version of the Maslov code as a new dynamical kernel for the next generation
MWFM.
REFERENCES:
Broutman, D., J. W. Rottman and S. D. Eckermann, A hybrid method for
analyzing wave propagation from a localized source, with application to
mountain waves,
Q. J.
R. Meteorol. Soc., 127, 129-146, 2001.
Broutman, D., J. W. Rottman and S. D. Eckermann, Maslov's method for
stationary hydrostatic mountain waves,
Q. J.
R. Meteorol. Soc., 128, 1159-1172, 2002.
Broutman, D., J. W. Rottman and S. D. Eckermann, A simplified Fourier method
for nonhydrostatic mountain waves, J. Atmos. Sci.,
(submitted), 2003. |
