The large-scale environments of the global populations of mesoscale convective complexes

The mean genesis environment was constructed for each of five mesoscale con vective complex (MCC) population centers around the world: Africa, Australi a, China, South America, and the United States. It is found that the enviro nments are very similar and exhibit many of the same dynamic and thermodyna mic structures that are present with systems in the United States. In parti cular, MCCs initiate within prominent baroclinic zones characterized by loc ally large values of lower-tropospheric vertical wind shear and convective available potential energy (CAPE). Typically, a low-level jet of air with l ow static stability, high equivalent potential temperature, oriented nearly perpendicular to the baroclinic zone, intrudes into the genesis region and is forced to ascend over a relatively shallow, surface-based layer of rela tively cool air. Pronounced warm advection accompanied by strong lower-trop ospheric veering overlays the surface-based cool layer. A local maximum in absolute humidity and a local minimum in static stability mark the favored region fur formation of the convective system. Low-level convergence, upper -level divergence, and an approaching midlevel vorticity maximum associated with a weak short-wave trough are also typical of the mean genesis environ ment.