Title: On a 3D Model with Anisotropic Rotating Convection and Phase Changes for DA

Author: Onno Bokhove (University of Leeds)
Steve Tobias (University of Leeds)
Tom Kent (University of Leeds)

We will explore the formulation of a 3D model with strong rotation and convection of Julian et al. (J. Fluid. Mech. 555, 2006), for use as an idealized model in data assimilation. This model can be derived from the strongly rotating, incompressible Boussinesq, parent equations. The main simplification is that the horizontal velocity is replaced by the geostrophic velocity, based on the assumption that the Rossby number is small. Hydrostatic balance is, however, not required. Key ingredients making the model of interest to data assimilation studies are the presence of rotating convection columns and gravity waves, while the strong rotation nonetheless simplifies the dynamics. Stratified quasi-geostrophic dynamics is a subset of this system. We will highlight and discuss these aspects in the model derivation.

To facilitate a compatible numerical discretization with its associated conservation properties, we will explore the Hamiltonian formulation of the model in the inviscid limit, as such a formulation concerns an integral or weak formulation. Finally, to introduce some of the complexity of precipitation modeling in Numerical Weather Prediction, we aim to introduce effects of phase changes by considering a fluid with two constituents: one with only vapor and solid phases and one inert carrier gas. Conceptually, instead of a water cycle, this introduces a two-phase cycle for the active constituent, such as is the case on Mars for CO2 or for iodine in a rotating laboratory Rayleigh-Benard experiment. In the latter case, a rotating cylindrical tank is heated from below, leading to sublimation into a visible violet iodine vapor, and cooled from the top, leading to crystallization.

GMAO Head: Steven Pawson Global Modeling and Assimilation Office NASA Goddard Space Flight Center

Curator: Nikki Privé Last Updated: Feb 9 2015