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The Divergence-free Net Coriolis Force creates Vertical Geostrophic Balance and Westward tilted Atmospheric Convection
  • Joseph Biello,
  • Matthew Igel
Joseph Biello
University of California Davis, University of California Davis

Corresponding Author:[email protected]

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Matthew Igel
University of California Davis, University of California Davis
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Abstract

There has been increasing realization that the non-traditional Coriolis force terms may have a significant effect on convective circulation and organization in the tropics. In this talk, we introduce the concept of the net Coriolis force of a fluid dynamical flow. In order to compute the net Coriolis force, we assume incompressible flow - and therefore incompressible net Corolis force. Through the Leray projection we are able to construct, both, the pressure needed to maintain an incompressible force, and the net Coriolis force, itself. We explore the effects of the net Coriolis force on basic flows by decomposing the velocity field using the Helmholtz decomposition, and we describe poloidal and horizontal flows separately. We then compute the net Coriolis force associated with the Traditional Corolis terms (proportional to the sine of latitude) and, separately, the net Non-Traditional Coriolis terms (proportional to the cosine of latitude). We show that all poloidal circulations - which are flows which lack a vertical component of vorticity - are in vertical gesotrophic balance. Therefore, the pressure induced by such flows is simply computed without the need to invert a Laplacian. Using the Dynamics of Non-rotating Updraft Tori (DoNUT), which is a polodial circulation framework introduced by Igel & Biello (2020) to describe the full kinematic circulation of atmospheric convection, we show that the net non-traditional Coriolis force has zero component in the vertical direction, is westward in the regions of upward flow, and recirculates eastward poleward of the upward flow. The resulting circulations lead to vertical/westward oriented momentum flux from the resulting Reynold’s stress terms. We will conclude by discussing implications of these circulations for tropical convective organization.