On Taking into Consideration the Upper Layers of the Atmosphere to Simulate Orographic Disturbances in the Troposphere

Abstract

This study considers the problem of upper boundary conditions with regard to simulating the phenomenon of airflow over mountains. A two-dimensional stationary nonlinear analytical model is used. In a three-layer upstream flow, the velocity does not depend on the height, and the vertical temperature gradients change from layer to layer. The lower layer is the troposphere, the middle layer is the lower stratosphere, and the upper layer is the whole upper atmosphere unlimited in height. The impact of changes in stability of the middle layer on the wave energy reflection from the upper layers and, finally, on tropospheric disturbances is examined. It is confirmed that the energy reflection especially grows when the middle-layer temperature gradient approaches the dry-adiabatic value, because the environmental resilience to vertical displacements in air particles disappears. It is shown that, even in such a case, energy reflection is not full and, consequently, the Long resonance is not possible in the atmosphere.