[Grad-postdoc-assn] Next ASP seminar by Mitch Moncrieff
Yumin Moon
ymoon at ucar.edu
Fri Feb 21 11:14:50 MST 2014
Hi all,
The next ASP seminar is going to be "Organized Convection in Global
Context" by Mitch Moncrieff (NCAR/CGD) at FL2 Large Auditorium, March
5 2014 11:00 a.m.
Satellite observations show that precipitating convective cloud
systems in Earth's atmosphere tend to organize into spatially coherent
structures embedded in fields of cumulus notably, but not only, in the
Tropics. At a fundamental level this property is analogous to
coherent structures in turbulent fluids. Although organization can
occur in traditional climate models with 100s-km computational meshes,
its morphology is usually not realistic. The reason for this
misbehavior is two-pronged. Firstly, convective parameterizations were
designed with turbulent mixing by transient cumulus in mind, and
regardless of coherent convective systems. Secondly, the model
resolution is too coarse to permit explicit systems. Organization
involves interaction between diabatic heating, momentum transport,
vertical shear and wave dynamics across a range of scales. We have
excellent knowledge of the O(1km - 1000km) meso-synoptic range from
field campaigns, cloud-system resolving models and dynamical analogs.
Now that operational global weather models and experimental climate
models both have O(10km) mesoscale-permitting meshes, we need to
seriously consider the representation of organized convection in these
models. Computational and theoretical insights are in place, and
high-resolution global weather analyses in the form of a 'virtual
global field campaign' provide useful information. The categories of
organization featured in this talk are propagating convective systems
over the continental United States and multiscale convective systems
associated with the Madden-Julian oscillation, the leading mode of
intraseasonal tropical variability.
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