Terms of Reference

The role of the Committee on Mesoscale Processes is to provide a forum to promote the basic scientific understanding of mesoscale events and phenomena occurring in the earth’s atmosphere and oceans, and to promote their accurate representation in conceptual and numerical models. From a dynamical point of view, "mesoscale" refers to circulations that are sufficiently large to be hydrostatic, yet too small in scale to be quasigeostrophic. Thus, the study of the mesoscale spans the traditional separation between the synoptic and planetary scales and the microscale. Examples of the former include baroclinic instability, planetary waves, blocking, and the general circulation, whereas examples of the latter include convection, cloud dynamics and microphysics, and small-scale gravity waves. Phenomena and processes that may be characterized as mesoscale include fronts and frontogenesis, inertia–gravity waves, ageostrophic and hydrostatic flows that are thermally or mechanically forces, mesoscale waves and instabilities, cloud systems resulting from the growth and interaction of convective elements and thus organized on scales significantly larger than individual convective plumes, waves and turbulence acting to transfer energy between the synoptic- and microscales, and the atmosphere’s dynamical response to cloud microphysics, radiation, and other processes rooted at small scales.