Role of Vertical Resolution in Numerical Models Towards the Intensification, Structure and Track of Tropical Cyclones

2010 ◽  
Vol 33 (4) ◽  
pp. 338-355 ◽  
Author(s):  
D. V. Bhaskar Rao ◽  
D. Hari Prasad ◽  
D. Srinivas ◽  
Y. Anjaneyulu
Keyword(s):  
Tropical Cyclones ◽  
Numerical Models ◽  
Vertical Resolution

scholarly journals A Note on the Numerical Representation of Surface Dynamics in Quasigeostrophic Turbulence: Application to the Nonlinear Eady Model

2009 ◽  
Vol 66 (4) ◽  
pp. 1063-1068 ◽  
Author(s):  
Ross Tulloch ◽  
K. Shafer Smith
Keyword(s):  
Numerical Models ◽  
Buoyancy Frequency ◽  
Complete Suppression ◽  
Numerical Representation ◽  
Vertical Resolution ◽  
Surface Dynamics ◽  
Coriolis Parameter ◽  
Theoretical Predictions ◽  
Vertical Grid ◽  
Similar Restriction

Abstract The quasigeostrophic equations consist of the advection of linearized potential vorticity coupled with advection of temperature at the bounding upper and lower surfaces. Numerical models of quasigeostrophic flow often employ greater (scaled) resolution in the horizontal than in the vertical (the two-layer model is an extreme example). In the interior, this has the effect of suppressing interactions between layers at horizontal scales that are small compared to Nδz/f (where δz is the vertical resolution, N the buoyancy frequency, and f the Coriolis parameter). The nature of the turbulent cascade in the interior is, however, not fundamentally altered because the downscale cascade of potential enstrophy in quasigeostrophic turbulence and the downscale cascade of enstrophy in two-dimensional turbulence (occurring layerwise) both yield energy spectra with slopes of −3. It is shown here that a similar restriction on the vertical resolution applies to the representation of horizontal motions at the surfaces, but the penalty for underresolving in the vertical is complete suppression of the surface temperature cascade at small scales and a corresponding artificial steepening of the surface energy spectrum. This effect is demonstrated in the nonlinear Eady model, using a finite-difference representation in comparison with a model that explicitly advects temperature at the upper and lower surfaces. Theoretical predictions for the spectrum of turbulence in the nonlinear Eady model are reviewed and compared to the simulated flows, showing that the latter model yields an accurate representation of the cascade dynamics. To accurately represent dynamics at horizontal wavenumber K in the vertically finite-differenced model, it is found that the vertical grid spacing must satisfy δz ≲ 0.3f/(NK); at wavenumbers K > 0.3f/(Nδz), the spectrum of temperature variance rolls off rapidly.

On the role of vertical and horizontal model resolution for the simulation of stratospheric transport

2021 ◽  
Author(s):  
Hella Garny ◽  
Simone Dietmüller ◽  
Roland Eichinger ◽  
Aman Gupta ◽  
Marianna Linz
Keyword(s):  
Climate Models ◽  
Horizontal Resolution ◽  
Climate Forcing ◽  
Numerical Dispersion ◽  
Mixing Efficiency ◽  
Vertical Resolution ◽  
Model Resolution ◽  
Residual Circulation ◽  
Year 2000

<p>The stratospheric transport circulation, or Brewer-Dobson Circulation (BDC), is often conceptually seperated into advection along the residual circulation and two-way mixing. In particular the latter part has recently been found to exert a strong influence on inter-model differences of mean age of Air (AoA), a common measure of the BDC. However, the precise reason for model differences in two-way mixing remains unknown, as many model<br>components in multi-model projects differ. One component that likely plays an important role is model resolution, both vertically and horizontally. To analyse this aspect, we carried out a set of simulations with identical and constant year 2000 climate forcing varying the spectral horizontal<br>resolution (T31,T42,T63,T85) and the number of vertical levels (L31,L47,L90). We find that increasing the vertical resolution leads to an increase in mean AoA. Most of this change can be attributed to aging by mixing. The mixing efficiency, defined as the ratio of isentropic mixing strength and the diabatic circulation, shows the same dependency on vertical resolution. While horizontal resolution changes do not systematically change mean AoA, we do<br>find a systematic decrease in the mixing efficiency with increasing horizontal resolution. Non-systematic changes in the residual circulation partly compensate the mixing efficiency changes, leading to the non-systematic mean AoA changes. The mixing efficiency changes with vertical and horizontal resolution are consistent with expectations on the effects of numerical dispersion on mean AoA. To further investigate the most relevant regions of mixing differences, we analyse height-resolved mixing efficiency differences. Overall, this work will help to shed light on the underlying reasons for the large biases of climate models in simulating stratospheric transport.</p>

scholarly journals The Role of Lower Crustal Rheology in Lithospheric Delamination During Orogeny

2021 ◽  
Vol 9 ◽  
Author(s):  
Lin Chen
Keyword(s):  
Lower Crust ◽  
Numerical Models ◽  
The Tibetan Plateau ◽  
Mantle Lithosphere ◽  
Laboratory Studies ◽  
Surface Uplift ◽  
Continental Lower Crust ◽  
Lower Crustal ◽  
Flow Laws

The continental lower crust is an important composition- and strength-jump layer in the lithosphere. Laboratory studies show its strength varies greatly due to a wide variety of composition. How the lower crust rheology influences the collisional orogeny remains poorly understood. Here I investigate the role of the lower crust rheology in the evolution of an orogen subject to horizontal shortening using 2D numerical models. A range of lower crustal flow laws from laboratory studies are tested to examine their effects on the styles of the accommodation of convergence. Three distinct styles are observed: 1) downwelling and subsequent delamination of orogen lithosphere mantle as a coherent slab; 2) localized thickening of orogen lithosphere; and 3) underthrusting of peripheral strong lithospheres below the orogen. Delamination occurs only if the orogen lower crust rheology is represented by the weak end-member of flow laws. The delamination is followed by partial melting of the lower crust and punctuated surface uplift confined to the orogen central region. For a moderately or extremely strong orogen lower crust, topography highs only develop on both sides of the orogen. In the Tibetan plateau, the crust has been doubly thickened but the underlying mantle lithosphere is highly heterogeneous. I suggest that the subvertical high-velocity mantle structures, as observed in southern and western Tibet, may exemplify localized delamination of the mantle lithosphere due to rheological weakening of the Tibetan lower crust.

scholarly journals The Role of Eyewall Turbulent Transport in the Pathway to Intensification of Tropical Cyclones

2021 ◽  
Author(s):  
Ping Zhu ◽  
Andrew Hazelton ◽  
Zhan Zhang ◽  
Frank Marks ◽  
Vijay Tallapragada
Keyword(s):  
Tropical Cyclones ◽  
Turbulent Transport

scholarly journals The role of Edge-Driven Convection in the generation of volcanism I: a 2D systematic study

2020 ◽  
Author(s):  
Antonio Manjón-Cabeza Córdoba ◽  
Maxim Ballmer
Keyword(s):  
Numerical Models ◽  
High Volume ◽  
Oceanic Lithosphere ◽  
Companion Paper ◽  
Small Scale ◽  
Continental Lithosphere ◽  
Transient Phenomenon ◽  
Mantle Viscosity ◽  
Wide Range

Abstract. The origin of intraplate volcanism is not explained by the plate tectonic theory, and several models have been put forward for explanation. One of these models involves Edge-Driven Convection (EDC), in which cold and thick continental lithosphere is juxtaposed to warm and thin oceanic lithosphere to trigger convective instability. To test whether EDC can produce long-lived high-volume magmatism, we run numerical models of EDC for a wide range of mantle properties and edge (i.e., the oceanic-continental transition) geometries. We find that the most important parameters that govern EDC are the rheological paramaters mantle viscosity η0 and activation energy Ea. However, even the maximum melting volumes found in our models are insufficient to account for island-building volcanism on old seafloor, such as at the Canary Islands and Cape Verde. Also, beneath old seafloor, localized EDC-related melting commonly transitions into widespread melting due to small-scale sublithospheric convection, inconsistent with the distribution of volcanism at these volcanic chains. In turn, EDC is a good candidate to sustain the formation of small seamounts on young seafloor, as it is a highly transient phenomenon that occurs in all our models soon after initiation. In a companion paper, we investigate the implications of interaction of EDC with mantle-plume activity.

scholarly journals The role of edge-driven convection in the generation of volcanism – Part 1: A 2D systematic study

Solid Earth ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 613-632
Author(s):  
Antonio Manjón-Cabeza Córdoba ◽  
Maxim D. Ballmer
Keyword(s):  
Numerical Models ◽  
High Volume ◽  
Oceanic Lithosphere ◽  
Companion Paper ◽  
Rheological Parameters ◽  
Small Scale ◽  
Transient Phenomenon ◽  
Mantle Viscosity ◽  
Wide Range

Abstract. The origin of intraplate volcanism is not explained by plate tectonic theory, and several models have been put forward for explanation. One of these models involves edge-driven convection (EDC), in which cold and thick continental lithosphere is juxtaposed with warm and thin oceanic lithosphere to trigger convective instability. To test whether EDC can produce long-lived high-volume magmatism, we run numerical models of EDC for a wide range of mantle properties and edge (i.e., the oceanic–continental transition) geometries. We find that the most important parameters that govern EDC are the rheological parameters mantle viscosity η0 and activation energy Ea. However, even the maximum melting volumes predicted by our most extreme cases are insufficient to account for island-building volcanism on old seafloor, such as at the Canary Islands and Cabo Verde. Also, beneath old seafloor, localized EDC-related melting commonly transitions into widespread melting due to small-scale sublithospheric convection, inconsistent with the distribution of volcanism at these volcano chains. In turn, EDC is a good candidate to sustain the formation of small seamounts on young seafloor, as it is a highly transient phenomenon that occurs in all our models soon after initiation. In a companion paper, we investigate the implications of interaction of EDC with mantle plume activity (Manjón-Cabeza Córdoba and Ballmer, 2021).

Rapidly rotating relativistic stars

1992 ◽  
Vol 340 (1658) ◽  
pp. 391-422 ◽  
Keyword(s):  
Neutron Stars ◽  
Numerical Models ◽  
Normal Modes ◽  
Rotating Stars ◽  
Relativistic Stars ◽  
Small Oscillations ◽  
Perfect Fluids ◽  
Upper Limits ◽  
Viscosity Limit

Within the last decade, significant progress has been made in modelling rotating stars in general relativity and in relating observable properties to the equation of state of matter at high density. A formalism describing rotating perfect fluids is presented and numerical models of neutron stars are briefly discussed, with emphasis on upper limits on mass and rotation. The equations governing small oscillations are reviewed, and a variational principle appropriate both to eulerian and lagrangian perturbations is obtained. This extends to relativity an eulerian principle used to find non-axisymmetric stability points for perfect fluids. A related eulerian approach has been recently used to obtain normal modes of rotating newtonian stars. The review concludes with an outline of this work and of the two types of instability that can restrict the range of neutron stars. In particular, current work shows that several kinds of effective viscosity limit the possible role of a non-axisymmetric instability driven by gravitational waves.

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