A Locally One-Dimensional Semi-Implicit Scheme for Global Gridpoint Shallow-Water Models

Kar, Sajal K.; Turco, R. P.; Mechoso, Carlos R.; Arakawa, Akio

doi:10.1175/1520-0493(1994)122<0205:alodsi>2.0.co;2

Cited by 10 publications

(4 citation statements)

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“…The single-layer shallow-water model used in this study is that described by Kar et al (1994). It is a global grid-point model which has been demonstrated to produce stable and accurate solutions at considerable computational economy.…”

Section: (B) the Shallow-water Modelmentioning

confidence: 99%

Upper‐tropospheric flow transitions during rapid tropical cyclone intensification

Davidson

Kar

2002

Quart J Royal Meteoro Soc

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SUMMARYEvidence is presented of upper-tropospheric ow transitions during rapid tropical cyclone (TC) intensication. Transitions occur when a mid-latitude upper trough, with a wind maximum on its eastern ank, located well to the west of a storm, relaxes as anticyclogenesis occurs near to, and east of, its equatorward extremity. During these episodes, the ow is characterized by weak inertial stability. It is proposed that this allows extremely rapid and large-scale changes to occur in the upper-level environment of the storm. The new environment provides seemingly favourable conditions of reduced wind shear, development of a downstream trough very near the storm, and access for the storm out ow to the tropical easterlies and mid-latitude westerlies.A global shallow-water model, initialized with objective analyses at the 200 hPa level, is used to study the phenomenon, and the interaction between the environmental ow and local sources of mass and momentum. The sources are used to represent the effects of inner-core deep convection in the out ow layer. Using the technique it seems possible, as a rst approximation, to isolate the environment from the vortex development. It is shown that ow transitions are mostly independent of the presence of the TC. Short term, local enhancement of divergence over the TC occurs during superposition of environmentally-induced divergence with the mass source. However, formation of the upper-level vortex is the distinguishing feature of the intensi cation, and this occurs during an upper-tropospheric ow transition. It is shown: (i) that the reduction in ventilation is associated with ow transitions, (ii) that these transitions directly in uence the development of the upper vortex of the TC via downstream development of a weak environmental trough, and (iii) that the transitions indirectly in uence the vortex development by allowing the momentum and mass sources to operate more ef ciently to assist in both the development of the vortex and the out ow channels at small radii.Several examples of ow transitions during intensi cation are presented to support the proposed hypothesis.

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Section: (B) the Shallow-water Modelmentioning

confidence: 99%

Upper‐tropospheric flow transitions during rapid tropical cyclone intensification

Davidson

Kar

2002

Quart J Royal Meteoro Soc

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“…For the momentum equations, it is preferable to apply the filter under the gradient operator of the pressure-gradient terms because this avoids spurious generation of vorticity. We were aware of this issue when designing the original model and tried the method of Kar et al (1994) but had trouble with it, especially for Neptune's strong winds at high latitudes, so we ended up filtering the wind tendencies themselves, which means the old model has the spurious vorticity generation problem. Fortunately, the trouble we experienced before has since been cleared up by the move to an implicit operator for high-order dissipation in the zonal direction, as described above.…”

Section: High-latitude Zonal Filtermentioning

confidence: 99%

“…The strategy we now employ is to filter the kinetic energy term under the gradient operator, plus the hybrid density, h, and the potential temperature, θ , which are the prognostic variables that generate the Montgomery potential and geopotential that appear under gradient operators in the pressure-gradient terms, but we no longer filter the winds themselves. In (56) of Dowling et al (1998) we now use α 1 = α 2 = 2, meaning we now follow Kar et al (1994).…”

Section: High-latitude Zonal Filtermentioning

confidence: 99%

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

Dowling

Bradley

Colon

et al. 2006

Icarus

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“…To circumvent this problem, some time splitting techniques have been applied to atmospheric models [2,3,5,10,12,18]. Splitting methods allow to decouple multi-dimensional elliptic equations into a set of 1D problems, which are solved very efficiently by direct Gelfand-Thomas algorithm.…”

Section: Introductionmentioning

confidence: 99%

Improved Semi-Lagrangian Stabilizing Correction Scheme for Shallow Water Equations

Bourchtein

2004

Computational Science - ICCS 2004

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Abstract. Improved splitting method based on stabilizing correction scheme is used for solving shallow water equations. Recently introduced by Douglas et al. technique is applied to reduce splitting errors. Accuracy and stability analysis showed that the developed scheme allows to chose extended time steps and is more accurate as compared with standard splitting method. The results of numerical experiments confirmed that presented scheme has almost the same computational efficiency as primitive stabilizing correction method and it continues to be accurate and stable for extended time steps up to 1 hour when primitive method fails.

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A Locally One-Dimensional Semi-Implicit Scheme for Global Gridpoint Shallow-Water Models

Cited by 10 publications

References 0 publications

Upper‐tropospheric flow transitions during rapid tropical cyclone intensification

Upper‐tropospheric flow transitions during rapid tropical cyclone intensification

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

Improved Semi-Lagrangian Stabilizing Correction Scheme for Shallow Water Equations

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