Ag. Laing et Jm. Fritsch, The large-scale environments of the global populations of mesoscale convective complexes, M WEATH REV, 128(8), 2000, pp. 2756-2776
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.