Joint Seminar: New Frontiers: Tropical Cyclone Modeling with NCAR's Variable-Resolution General Circulation Model CAM-SE

Modeling of tropical cyclones in General Circulation Models (GCMs) has traditionally proved 
challenging. Tropical cyclones are significantly under-resolved, if not completely
unresolved, at traditional GCM grid resolutions of 50-300 km. However, recent gains in
computational resources and advances in GCM model design now allow for GCM simulations with
grid spacings as small as 12-30 km. At these resolutions, models are able to more effectively
capture key features of tropical cyclones.


This talk surveys a novel variable-resolution mesh approach that allows for high spatial 
resolutions in areas of interest. The statically-nested, variable-mesh option has recently
been introduced into the Spectral Element (SE) dynamical core of the Community Atmosphere
Model (CAM) which is under development at various U.S. Department of Energy laboratories and
the National Center for Atmospheric Research (NCAR). The talk gives an overview of the
variable-resolution mesh approach, and evaluates its scientific properties. In particular, we
will discuss the characteristics of tropical cyclone simulations in a hierarchy of test
scenarios with increasing complexity. They include the movement of tropical cyclones in a dry
environment, address the representation of idealized cyclones in aqua-planet experiments, and
showcase short-term and long-term tropical cyclone simulations in CAM when driven with
prescribed sea surface temperatures. Special attention is paid to the characteristics of
tropical cyclones in the grid transition regions, and the comparison of variable- and uniform-
resolution experiments. It is shown that the variable-resolution CAM-SE model has the
potential to become a future tool for regional climate assessments.




15:15 Uhr


Bundesstr. 53, room 022/023
Seminar Room 022/023, Ground Floor, Bundesstrasse 53, 20146 Hamburg, Hamburg


Christiane Jablonowski, University of Michigan


Jörn Behrens

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