The EPIC atmospheric model with an isentropic/terrain-following hybrid vertical coordinate

Dowling, T. E.; Bradley, M. E.; Colon, Edward; Kramer, J. W. J. L.; LeBeau, Raymond P.; Lee, Grace C.H.; Mattox, Timothy I.; Morales-Juberías, R.; Palotai, Csaba; Parimi, Vimal K.; Showman, Adam P.

doi:10.1016/j.icarus.2006.01.003

Cited by 51 publications

(33 citation statements)

References 23 publications

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“…The simulations used the Explicit Planetary Isentropic Coordinate General Circulation Model (EPIC GCM version 4.03; Dowling et al, 2006), which had already been used to conduct simulations of vortices on Neptune (LeBeau and , along with a few early simulations of vortices on Uranus (Deng and LeBeau, 2007). Those early UDS simulations suggested the possibility of month-long vortices comparable to the observed feature.…”

Section: Numerical Simulations Of the Dark Spot Of Uranusmentioning

confidence: 99%

The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations

Hammel

Sromovsky

Fry

et al. 2009

Icarus

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Section: Numerical Simulations Of the Dark Spot Of Uranusmentioning

confidence: 99%

The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations

Hammel

Sromovsky

Fry

et al. 2009

Icarus

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“…T. This is largely different from Herrnstein and Dowling (2007), in which the superrotation with topography is 50% weaker than that without topography. The lowermost-level flow has a maximum velocity of ∼27 m s −1 in Herrnstein and Dowling's model with low vertical resolution, to which the sophisticated Planetary Boundary Layer (PBL) model using a Spalart-Allmaras scheme (Dowling et al, 2006) is applied. On the other hand, the lowermost-level flow is sufficiently decelerated by the surface drag in the thin layer between σ = 1 and 0.99 (∼100 m) in the present study.…”

Section: Summary and Discussionmentioning

confidence: 99%

Influences of Venus’ topography on fully developed superrotation and near-surface flow

Yamamoto

Takahashi

2009

Earth Planet Sp

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We investigate the influence of topography on Venus' atmospheric general circulation. Based on comparative simulations with and without the Venusian topography, we elucidate the role of the topography in the fully developed superrotation. Orographically forced stationary waves are predominant over Mt. Maxwell: slightly weakening the superrotation near the cloud top. Differently from previous GCM results, the orographically forced waves do not produce significant asymmetry between the northern and southern hemispheric superrotations in the present model. Weak surface flows from mountains to lowlands are caused by the pressure dependence of the Newtonian cooling. The pattern and magnitude of the near-surface flow are largely different from those simulated in the Herrnstein and Dowling (2007) model. This implies that the parameterizations of physical processes (such as Newtonian cooling, turbulence, diffusion, and surface drag) and the model resolution could significantly influence the pattern and magnitude of the near-surface flow and the orographical forcing of planetary-scale stationary waves.

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“…The algorithm presented here is robust in practice-variations of it have been used extensively in the EPIC model (Dowling et al, 2006) over the past three years, and it is now the model's default ‡ . In addition to gaining significantly on accuracy, we prefer the Green-Gauss formulation because we do not have to modify the algorithm when switching from terrestrial planets to gas-giant planets (for which the ortho-/parahydrogen mix splits the pressure gradient in PDE form), or from the terrain-following to the isentropiccoordinate regions in our hybrid-coordinate model.…”

Section: Discussionmentioning

confidence: 99%

“…truncation error over traditional, PDE formulations of the horizontal PGF. Here, we examine the additional reduction provided by the 3D formulation, and its computational cost, by testing it in the EPIC atmospheric model (Dowling et al, 2006), which uses a longitude-latitude grid.…”

Section: Accuracy and Performancementioning

confidence: 99%

Using 3D finite volume for the pressure‐gradient force in atmospheric models

Bradley

Dowling

2012

Quart J Royal Meteoro Soc

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The horizontal pressure-gradient force is traditionally discretized in partialdifferential equation (PDE) form in atmospheric models, but may alternatively be discretized as the net normal surface force divided by the mass, which is referred to as the Green-Gauss method in computational fluid dynamics (CFD). The latter approach is ubiquitous in engineering because of the utility of unstructured grids; in the meteorological context Lin derived in 1997 a two-dimensional (2D), planeparallel, Green-Gauss algorithm and showed that it eliminated inaccuracies related to using terrain-following (sigma) coordinates in steep terrain. Although a hierarchy of three-dimensional (3D) algorithms have been developed by the CFD community, with varying cost-to-benefit trade-offs, work remains to be done to take full advantage of the 3D approach in atmospheric models. Here, we move in this direction by extending Lin's 2D algorithm to 3D. As is true of all Green-Gauss implementations, our algorithm is the same regardless of choice of vertical coordinate or number of fluid constituents. We show that the modifications to the 2D algorithm may be written in the form of additive terms composed of differences of the squares of the top and bottom tilts of the finite-volume faces; the cases for which the 2D and 3D algorithms are identical are then straightforward to discern. For plane-parallel geometry, we include explicit finite-volume formulae for the longitude-latitude and general convex quadrilateral planforms, which includes the cubed-sphere grid, with arbitrary geopotentials on the eight corners. Compared with the 2D version, the 3D algorithm yields approximately a 10% reduction in truncation error and, in the context of a general circulation model, it requires only about a 1% increase in run time.

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The EPIC atmospheric model with an isentropic/terrain-following hybrid vertical coordinate

Cited by 51 publications

References 23 publications

The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations

The Dark Spot in the atmosphere of Uranus in 2006: Discovery, description, and dynamical simulations

Influences of Venus’ topography on fully developed superrotation and near-surface flow

Using 3D finite volume for the pressure‐gradient force in atmospheric models

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