Numerical simulation studies of two-Dimensional turbulence: I. Models of statistically steady turbulence

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Abstract
It is demonstrated by numerical simulation that the addition of a linear drag term on the forced viscous vorticity equation allows the development of statistically steady-state two-dimensional turbulence, which then can be considered an analog of the large scale atmosphere. Two different types and two scales of forcing are applied, and the results are interpreted in terms of a Kovasznay-type closure theory. The energy spectrum is similar to that predicted by Kraichnan for forced two-dimensional turbulence but the drag term produces some significant modifications. Certain results are extrapolated to make predictions of the energy distribution in the large scale atmosphere. The predicted scale of maximum atmospheric energy is not easily tested, but seems somewhat too small. The relationships between two-dimensional turbulence and Charney's model of geostrophic turbulence are discussed.