[Grad-postdoc-assn] Next ASP seminar by Mitch Moncrieff

[Yumin Moon]

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.