[A-AS05] Large-scale moisture and organized cloud systems

[AAS05-01] Coupling Momentum and Variance in a MMF with a 2D CRM

★Invited Papers

*Walter Michael Hannah¹, Kyle Pressel², Mikhail Ovchinnikov², Qiu Yang², Ruby Leung², Gregory Elsaesser³, Matthew Norman⁴, Ben Hillman⁵ (1.Lawrence Livermore National Laboratory, 2.Pacific Northwest National Laboratory, 3.NASA, 4.Oak Ridge Leadership Computing Facility, 5.SNL)

Keywords:atmospheric modelling, multiscale modelling framework, convective momentum transport, GPU acceleration, tropical variability

An atmospheric multiscale modeling framework (MMF) allows an explicit representation of convection by coupling a cloud resolving model (CRM) with a general circulation model (GCM). This avoids the need for conventional parameterizations of clouds and turbulence. Traditional MMF implementations often use a 2D CRM with periodic boundary conditions to constrain the computational cost, but some consequences of this approach are that convective momentum transport cannot be explicitly represented and small-scale fluctuations within the CRM cannot be transported by the large-scale flow. These limitations can be problematic because they force the model to ignore key atmospheric processes. Two enhancements have been implemented in the E3SM-MMF to address these deficiencies. The first is the momentum transport scheme of Tulich (2015) in which the large-scale momentum field is represented in the CRM by two scalars, which allows the 3D momentum transport to be approximated by a 2D CRM. The second feature is a scheme that allows small scale fluctuations within the CRM to be transported between CRM instances on the global grid.