scholarly journals Steady Large-Scale Ocean Flows in Spherical Coordinates

Oceanography ◽  
2018 ◽  
Vol 31 (3) ◽  
pp. 42-50 ◽  
Author(s):  
Adrian Constantin ◽  
◽  
Robin Johnson
Keyword(s):  
Large Scale ◽  
Spherical Coordinates ◽  
Ocean Flows

scholarly journals Coronal ejections from convective spherical shell dynamos

2011 ◽  
Vol 7 (S286) ◽  
pp. 154-158 ◽  
Author(s):  
J. Warnecke ◽  
P. J. Käpylä ◽  
M. J. Mantere ◽  
A. Brandenburg
Keyword(s):  
Magnetic Field ◽  
Spherical Shell ◽  
Large Scale ◽  
Convection Zone ◽  
Three Dimensional ◽  
Simplified Model ◽  
Spherical Coordinates ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Large Scale Magnetic Field

AbstractWe present a three-dimensional model of rotating convection combined with a simplified model of a corona in spherical coordinates. The motions in the convection zone generate a large-scale magnetic field which is sporadically ejected into the outer layers above. Our model corona is approximately isothermal, but it includes density stratification due to gravity.

scholarly journals From convection rolls to finger convection in double-diffusive turbulence

2015 ◽  
Vol 113 (1) ◽  
pp. 69-73 ◽  
Author(s):  
Yantao Yang ◽  
Roberto Verzicco ◽  
Detlef Lohse
Keyword(s):  
Temperature Gradient ◽  
Large Scale ◽  
Salinity Gradient ◽  
Density Ratio ◽  
Lewis Number ◽  
Salt Fingers ◽  
Wide Range ◽  
Ocean Flows ◽  
Convection Rolls ◽  
Double Diffusive

Double-diffusive convection (DDC), which is the buoyancy-driven flow with fluid density depending on two scalar components, is ubiquitous in many natural and engineering environments. Of great interests are scalars' transfer rate and flow structures. Here we systematically investigate DDC flow between two horizontal plates, driven by an unstable salinity gradient and stabilized by a temperature gradient. Counterintuitively, when increasing the stabilizing temperature gradient, the salinity flux first increases, even though the velocity monotonically decreases, before it finally breaks down to the purely diffusive value. The enhanced salinity transport is traced back to a transition in the overall flow pattern, namely from large-scale convection rolls to well-organized vertically oriented salt fingers. We also show and explain that the unifying theory of thermal convection originally developed by Grossmann and Lohse for Rayleigh–Bénard convection can be directly applied to DDC flow for a wide range of control parameters (Lewis number and density ratio), including those which cover the common values relevant for ocean flows.

scholarly journals Efficient 3‐D Large‐Scale Forward Modeling and Inversion of Gravitational Fields in Spherical Coordinates With Application to Lunar Mascons

2019 ◽  
Vol 124 (4) ◽  
pp. 4157-4173 ◽  
Author(s):  
Guangdong Zhao ◽  
Bo Chen ◽  
Leonardo Uieda ◽  
Jianxin Liu ◽  
Mikhail K. Kaban ◽  
...  
Keyword(s):  
Large Scale ◽  
Forward Modeling ◽  
Spherical Coordinates ◽  
Gravitational Fields ◽  
And Inversion

Sparse magnetic vector inversion in spherical coordinates

Geophysics ◽  
2020 ◽  
Vol 85 (3) ◽  
pp. J33-J49 ◽  
Author(s):  
Dominique Fournier ◽  
Lindsey J. Heagy ◽  
Douglas W. Oldenburg
Keyword(s):  
Large Scale ◽  
Tectonic Deformation ◽  
Magnetic Survey ◽  
Spherical Coordinates ◽  
Magnetic Vector ◽  
Magnetization Direction ◽  
Spherical Coordinate ◽  
Magnetic Field Data ◽  
Ultramafic Intrusion ◽  
Vector Inversion

Magnetic vector inversion (MVI) has received considerable attention over recent years for processing magnetic field data that are affected by remanent magnetization. However, the magnetization models obtained with current inversion algorithms are generally too smooth to be easily interpreted geologically. To address this, we have reviewed the MVI formulated in a spherical coordinate system. We tackle convergence issues posed by the nonlinear transformation from Cartesian to spherical coordinates by using an iterative sensitivity weighting approach and a scaling of the spherical parameters. The spherical formulation allows us to impose sparsity assumptions on the magnitude and direction of magnetization independently and, as a result, the inversion recovers simpler and more coherent magnetization orientations. The numerical implementation of our algorithm on large-scale problems is facilitated by discretizing the forward problem using tiled octree meshes. All of our results are generated using the open-source SimPEG software. We determine the enhanced capabilities of our algorithm on a large airborne magnetic survey collected over the Kevitsa Ni-Cu-platinum group elements (PGE) deposit. The recovered magnetization direction inside the ultramafic intrusion and in the host stratigraphy is consistent with laboratory measurements and provides evidence for tectonic deformation.

scholarly journals Rigid Sets and Coherent Sets in Realistic Ocean Flows

2022 ◽  
Author(s):  
Florian Feppon ◽  
Pierre Lermusiaux
Keyword(s):  
Large Scale ◽  
Ocean Current ◽  
Island Region ◽  
New Methods ◽  
Ocean Flows ◽  
Flow Map ◽  
Matrix Free ◽  
The Western Pacific ◽  
Volume Preserving ◽  
Simulated Flow

Abstract. This paper focuses on the extractions of Lagrangian Coherent Sets from realistic velocity fields obtained from ocean data and simulations, each of which can be highly resolved and non volume-preserving. We introduce two novel methods for computing two formulations of such sets. First, we propose a new “diffeomorphism-based” criterion to extract “rigid sets”, defined as sets over which the flow map acts approximately as a rigid transformation. Second, we develop a matrix-free methodology that provides a simple and efficient framework to compute “coherent sets” with operator methods. Both new methods and their resulting rigid sets and coherent sets are illustrated and compared using three numerically simulated flow examples, including a high-resolution realistic, submesoscale to large-scale dynamic ocean current field in the Palau Island region of the western Pacific Ocean.

Some comments about observations and image processing of comet 29P/Schwassmann-Wachmann 1

1999 ◽  
Vol 173 ◽  
pp. 243-248
Author(s):  
D. Kubáček ◽  
A. Galád ◽  
A. Pravda
Keyword(s):  
Image Processing ◽  
Large Scale ◽  
Harvard College ◽  
Oak Ridge ◽  
Large Scale Structures ◽  
Short Period Comet ◽  
Short Period ◽  
Scale Structures ◽  
Harvard College Observatory ◽  
Period Comet

AbstractUnusual short-period comet 29P/Schwassmann-Wachmann 1 inspired many observers to explain its unpredictable outbursts. In this paper large scale structures and features from the inner part of the coma in time periods around outbursts are studied. CCD images were taken at Whipple Observatory, Mt. Hopkins, in 1989 and at Astronomical Observatory, Modra, from 1995 to 1998. Photographic plates of the comet were taken at Harvard College Observatory, Oak Ridge, from 1974 to 1982. The latter were digitized at first to apply the same techniques of image processing for optimizing the visibility of features in the coma during outbursts. Outbursts and coma structures show various shapes.

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