East Asia and Western Pacific METEOROLOGY AND CLIMATE

559
RECENT RESULTS IN LIMITED-AREA NUMERICAL WEATHER PREDICTION
Simon Wei-Jen Chang
Rangarao Venkata Madala
Keith Denis Sashegyi
Atmospheric Physics Branch, Space Science Division
U. S. Naval Research Laboratory, Washington, D. C. 20375
ABSTRACT
Several improvements to the Naval Research Laboratory (NRL)
limited area weather prediction system have recently been incorporated.
A multi-layer planetary boundary layer parameterization based on the
tubulent kinetic energy and dissipation rate has been tested and
implemented to the system. This results in an improvement in the
forecast of finer mesoscale sturctures. The tropical cyclone version of
the model is used to study the outflow layer structure of tropical
cyclones. It is found there exists secondary circulations around the
outflow jet which may play an important role in the interaction between
tropical cyclone and upper tropospheric large scale systems, A new
vertical mode initialization is incorporated to the prediction system,
which proves to be an effective way to suppress oscillations in the
early hours of model integration due to initial imbalance. And finally,
a nested grid version of the NRL weather prediction is being developed.
I. INTRODUCTION.
Simulation studies with the newly improved U. S. Naval Research
Laboratory (NRL) limited-area numerical weather prediction system have
been carried out recently at NRL. The NRL prediction system is
maintained on the CRAY X-MP/24 at NRL. Advancements and improvements
are continuously periodically incorporated into the system. Basic and
applied research and studies are conducted with the model at NRL and
other research institutes.