[Grad-postdoc-assn] ASP seminar by Joe Klemp tomorrow

[Yumin Moon]

Hello all,

The next ASP seminar will be tomorrow (Feb/20) 03:30pm at FL2
Large Auditorium, by Joe Klemp (NCAR/MMM). This is a joint MMM/ASP
seminar.

The title of his talk is "The Evolution of Nonhydrostatic
Meteorological Modeling: from Cloud to Global Scales."

Nonhydrostatic processes in the atmosphere are characterized by
features in which the horizontal and vertical length scales are
comparable. Because the fully compressible equations of motion admit
acoustic modes as well as gravity-wave and rotational modes, much
early modeling emphasis focused on developing efficient numerical
techniques to accommodate these fast moving sound waves, which are
typically not of meteorological interest. Several approaches have
evolved over the years to mitigate these acoustic constraints,
employing either semi-implicit or split-explicit time integration
techniques, filtered (anelastic) equation sets, or artificial
compressibility approximations. Early 3-D nonhydrostatic modeling in
the 1970’s-80’s focused heavily on idealized simulations of moist
convective storms. Due to the significant limitations in computing
power, strong emphasis was placed on developing upper and lateral
boundary conditions for relatively small model domains that allow the
outward propagation of gravity-wave energy with minimal reflection. By
the 1990’s, nonhydrostatic research models with full physics were
being successfully employed to forecast the evolution of convection in
real weather systems, and by the next decade the use of nonhydrostatic
numerical weather prediction (NWP) models for operational
regional/mesoscale forecasting became routine.  With the continuing
advances in computing power, it is now becoming feasible to consider
running global atmospheric models at high resolutions O(km) that
require the inclusion of nonhydrostatic processes. In designing the
numerical techniques for global nonhydrostatic models, strong emphasis
is placed on conservation properties and on scalability to large
numbers of processors. After considering alternative approaches, we
are developing a global nonhydrostatic Model for Prediction Across
Scales (MPAS) using finite-volume numerics with C-grid staggering on a
variable resolution unstructured Voronoi (nominally hexagonal) mesh
for the horizontal discretization on the sphere. These numerics are
intended to provide a unified modeling system that is well suited for
future NWP, regional-climate, and climate applications.