Interactive Line Thermals in a Convective Layer: A Numerical Simulation

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  • 1 National Center for Atmospheric Research Boulder, Colo. 80303
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Abstract

This paper is concerned with the time evolution of interactive dry line thermals in a convective layer. The temperature perturbations which produce these line thermals are randomly chosen. Since the domain of computation is the x-z plane, the evolving flow field is described by the streamfunction, vorticity, and the potential temperature. The nonlinear acceleration terms were differenced by an Arakawa scheme and the time differencing was the second-order, explicit, two-step Adams-Bashforth scheme. The turbulent transfer terms were given by a nonlinear formulation based on the work of Lilly and Smagorinsky. The convective layers in our numerical experiments were simulated by releasing a single set of thermals and by successive releases of thermals. Even though our work is a two-dimensional simulation, our results were consistent with the gross properties of real convective fields reported by several investigators. Hence, our system is a relatively inexpensive model that can be used to study convective layers over irregular surfaces and terrain.

Abstract

This paper is concerned with the time evolution of interactive dry line thermals in a convective layer. The temperature perturbations which produce these line thermals are randomly chosen. Since the domain of computation is the x-z plane, the evolving flow field is described by the streamfunction, vorticity, and the potential temperature. The nonlinear acceleration terms were differenced by an Arakawa scheme and the time differencing was the second-order, explicit, two-step Adams-Bashforth scheme. The turbulent transfer terms were given by a nonlinear formulation based on the work of Lilly and Smagorinsky. The convective layers in our numerical experiments were simulated by releasing a single set of thermals and by successive releases of thermals. Even though our work is a two-dimensional simulation, our results were consistent with the gross properties of real convective fields reported by several investigators. Hence, our system is a relatively inexpensive model that can be used to study convective layers over irregular surfaces and terrain.

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