Browsing Mathematics by Author "Thuburn, John"
Now showing items 113 of 13

Effective diffusion of scalar fields in a chaotic flow
Turner, M. R.; Gilbert, Andrew D.; Thuburn, John (American Institute of Physics, 2008)The advection of a tracer field in a fluid flow can create complex scalar structures and increase the effect of weak diffusion by orders of magnitude. One tool to quantify this is to measure the flux of scalar across contour ... 
An Energy Conserving Restoration Scheme for the Shallow Water Equations.
Kent, James; Jablonowski, C; Thuburn, John; Wood, Nigel (Wiley, 20151120)The numericalmethods that solve the governing equations in an atmospheric dynamical core are designed to dissipate potential enstrophy and prevent the buildup of kinetic energy at the grid scale. A side effect of this is ... 
A framework for mimetic discretization of the rotating shallowwater equations on arbitrary polygonal grids
Thuburn, John; Cotter, C.J. (Society for Industrial and Applied Mathematics, 2012)Accurate simulation of atmospheric flow in weather and climate prediction models requires the discretization of the governing equations to have a number of desirable properties. Although these properties can be achieved ... 
The influence of periodic islands in the flow on a scalar tracer in the presence of a steady source
Turner, M. R.; Thuburn, John; Gilbert, Andrew D. (American Institute of Physics, 2009)In this paper we examine the influence of periodic islands within a time periodic chaotic flow on the evolution of a scalar tracer. The passive scalar tracer is injected into the flow field by means of a steady source term. ... 
An inherently massconserving semiimplicit semiLagrangian discretisation of the shallowwater equations on the sphere
Zerroukat, M.; Wood, Nigel; Staniforth, A.; White, A.A.; Thuburn, John (Royal Meteorological Society, 2009)For the shallowwater equations on the sphere, an inherently massconserving semiLagrangian discretisation (SLICE) of the continuity equation is coupled with a semiimplicit semiLagrangian discretisation of the momentum ... 
Numerical representation of geostrophic modes on arbitrarily structured Cgrids
Thuburn, John; Ringler, T.D.; Skamarock, W.C.; Klemp, J.B. (Elsevier, 2009)A Cgrid staggering, in which the mass variable is stored at cell centers and the normal velocity component is stored at cell faces (or edges in two dimensions) is attractive for atmospheric modeling since it enables a ... 
Numerical wave propagation on the hexagonal Cgrid
Thuburn, John (Elsevier, 2008)Inertiogravity mode and Rossby mode dispersion properties are examined for discretizations of the linearized rotating shallow water equations on a regular hexagonal Cgrid in planar geometry. It is shown that spurious ... 
On the form of the viscous term for two dimensional NavierStokes flows
Gilbert, Andrew D.; Riedinger, X; Thuburn, John (Oxford University Press, 20140227)The form of the viscous term is discussed for incompressible flow on a twodimensional curved surface S and for the shallow water equations. In the case of flow on a surface three versions are considered. These correspond ... 
A primaldual mimetic finite element scheme for the rotating shallow water equations on polygonal spherical meshes
Thuburn, John; Cotter, C.J. (Elsevier, 20150601)A new numerical method is presented for solving the shallow water equations on a rotating sphere using quasiuniform polygonal meshes. The method uses special families of finite element function spaces to mimic key ... 
Processes controlling tropical tropopause temperature and stratospheric water vapor in climate models
Hardiman, SC; Boutle, IA; Bushell, AC; Butchart, N; Cullen, MJP; Field, Paul R.; Furtado, K; Manners, James; Milton, Sean; Morcrette, C; O'Connor, FM; Shipway, BJ; Smith, Chris; Walters, DN; Willett, MR; Williams, Keith D.; Wood, Nigel; Lukeabraham, N; Keeble, J; Maycock, AC; Thuburn, John; Woodhouse, MT (American Meteorological Society, 20150519)A warm bias in tropical tropopause temperature is found in the Met Office Unified Model (MetUM), in common with most models from phase 5 of CMIP (CMIP5). Key dynamical, microphysical, and radiative processes influencing ... 
A semiimplicit version of the MPASatmosphere dynamical core
Sandbach, SD; Thuburn, John; Vassilev, D; Duda, MG (American Meteorological Society, 20150529)An important question for atmospheric modeling is the viability of semiimplicit time integration schemes on massively parallel computing architectures. Semiimplicit schemes can provide increased stability and accuracy. ... 
A unified approach to energy conservation and potential vorticity dynamics for arbitrarilystructured Cgrids
Ringler, T.D.; Thuburn, John; Klemp, J.B.; Skamarock, W.C. (Elsevier, 2010)A numerical scheme applicable to arbitrarilystructured Cgrids is presented for the nonlinear shallowwater equations. By discretizing the vectorinvariant form of the momentum equation, the relationship between the ... 
The unified model, a fullycompressible, nonhydrostatic, deep atmosphere global circulation model, applied to hot Jupiters
Mayne, Nathan J.; Baraffe, I.; Acreman, David M.; Smith, Chris; Browning, Matthew K.; Amundsen, David S.; Wood, Nigel; Thuburn, John; Jackson, David R. (EDP Sciences for European Southern Observatory (ESO), 2013)We are adapting the global circulation model (GCM) of the UK Met Office, the socalled unified model (UM), for the study of hot Jupiters. In this work we demonstrate the successful adaptation of the most sophisticated ...