The representation of gravity waves in atmospheric general circulation models (GCMs)

A potential long-term application of infrasound detection is related to the fact that nonlinear mountain flow dynamics and breaking gravity waves (GWs) in the high atmosphere produce infrasounds and/or affect the propagation of the infrasounds. In the future, we can imagine that the compressible models developed in meteorology will permit to link these mesoscale meteorological events to the infrasounds they produce. Nowadays, the parameterization of GWs in numerical weather prediction models (NWP) and general circulation models (GCM) could also be used to predict the places where the infrasounds are produced. The paper here does not address these issues specifically, but recall that nonlinear mountain flow dynamics and breaking GWs are very significant for the Atmospheric Climate. To establish this, we discuss how these effects are represented in GCMs, and which impacts they have on the climate of these models. First, a subgrid-scale orographic drag scheme is presented that includes both GWs drag and low-level drag that are based on well-understood mesoscale mountain flow dynamics. Second, the nonorographic GWs drag schemes used in most GCMs is presented that include a middle atmosphere. The impacts of these different schemes on the LMDz-GCM extended to the middle atmosphere are detailed.