A Theoretical Investigation of Convective Patterns in the Lee of the Colorado Rockies

摘要

The western Great Plains are observed to be the formation region for many of the summer convective systems in the central United States. Convective activity is greatly reduced in the immediate lee of the Colorado and New Mexico Rockies while it is intensified about a hundred kilometers eastward. An explanation of these observed convective patterns is proposed on the basis of a regional scale Rocky Mountains-Great Plains circulation system. A two-dimensional numerical model of a large scale mountain-plain circulation is presented which includes the effect of a slightly sloping plain. The equations are integrated over periods of two to eight hours for various initial conditions of thermal stability and ambient wind. An increase in thermal stability is found to suppress the developing circulation while the circulation is enhanced by an ambient shearing wind. Typical observed stability and ambient wind fields yield an interacting two cell circulation with a strong cell over the mountain slope and a weaker cell over the plain. (Author)