R. C. Oehmke

Space Weather Modeling Framework: A new tool for the space science community

[1] The Space Weather Modeling Framework (SWMF) provides a high-performance flexible framework for physics-based space weather simulations, as well as for various space physics applications. The SWMF integrates numerical models of the Solar Corona, Eruptive Event Generator, Inner Heliosphere, Solar Energetic Particles, Global Magnetosphere, Inner Magnetosphere, Radiation Belt, Ionosphere Electrodynamics, and Upper Atmosphere into a high-performance coupled model. The components can be represented with alternative physics models, and any physically meaningful subset of the components can be used. The components are coupled to the control module via standardized interfaces, and an efficient parallel coupling toolkit is used for the pairwise coupling of the components. The execution and parallel layout of the components is controlled by the SWMF. Both sequential and concurrent execution models are supported. The SWMF enables simulations that were not possible with the individual physics models. Using reasonably high spatial and temporal resolutions in all of the coupled components, the SWMF runs significantly faster than real time on massively parallel supercomputers. This paper presents the design and implementation of the SWMF and some demonstrative tests. Future papers will describe validation (comparison of model results with measurements) and applications to challenging space weather events. The SWMF is publicly available to the scientific community for doing geophysical research. We also intend to expand the SWMF in collaboration with other model developers.

Block-Structured Adaptive Grids on the Sphere: Advection Experiments

Abstract A spherical 2D adaptive mesh refinement (AMR) technique is applied to the so-called Lin–Rood advection algorithm, which is built upon a conservative and oscillation-free finite-volume discretization in flux form. The AMR design is based on two modules: a block-structured data layout and a spherical AMR grid library for parallel computer architectures. The latter defines and manages the adaptive blocks in spherical geometry, provides user interfaces for interpolation routines, and supports the communication and load-balancing aspects for parallel applications. The adaptive grid simulations are guided by user-defined adaptation criteria. Both statically and dynamically adaptive setups that start from a regular block-structured latitude–longitude grid are supported. All blocks are logically rectangular, self-similar, and independent data units that are split into four in the event of refinement requests, thereby doubling the horizontal resolution. Grid coarsenings reverse this refinement principle. ...

Block-structured adaptive meshes and reduced grids for atmospheric general circulation models

Adaptive mesh refinement techniques offer a flexible framework for future variable-resolution climate and weather models since they can focus their computational mesh on certain geographical areas or atmospheric events. Adaptive meshes can also be used to coarsen a latitude–longitude grid in polar regions. This allows for the so-called reduced grid setups. A spherical, block-structured adaptive grid technique is applied to the Lin–Rood finite-volume dynamical core for weather and climate research. This hydrostatic dynamics package is based on a conservative and monotonic finite-volume discretization in flux form with vertically floating Lagrangian layers. The adaptive dynamical core is built upon a flexible latitude–longitude computational grid and tested in two- and three-dimensional model configurations. The discussion is focused on static mesh adaptations and reduced grids. The two-dimensional shallow water setup serves as an ideal testbed and allows the use of shallow water test cases like the advection of a cosine bell, moving vortices, a steady-state flow, the Rossby–Haurwitz wave or cross-polar flows. It is shown that reduced grid configurations are viable candidates for pure advection applications but should be used moderately in nonlinear simulations. In addition, static grid adaptations can be successfully used to resolve three-dimensional baroclinic waves in the storm-track region.

A PHYSICS-BASED SOFTWARE FRAMEWORK FOR SUN-EARTH CONNECTION MODELING

Abstract The Space Weather Modeling Framework (SWMF) has been developed to provide NASA and the modeling community with a high-performance computational tool with “plug-and-play” capabilities to model the physics from the surface of the Sun to the upper atmosphere of the Earth. Its recently released working prototype includes five components for the following physics domains: Inner Heliosphere, Global Magnetosphere, Inner Magnetosphere, Ionosphere Electrodynamics and Upper Atmosphere. The SWMF is a structured collection of software building blocks to develop components for Sun-Earth system modeling, to couple them, and to assemble them into applications. A component is created from the user-supplied physics module by adding a wrapper, which provides the control functions, and coupling interface to perform the data exchange with other components. In its fully developed form, the SWMF will incorporate several more components (for example Solar Energetic Particles and Radiation Belt). It can also incorporate different versions – developed by the Sun-Earth modeling community – for each of the components. The SWMF Control Module is responsible for component registration, processor layout for each component, execution, and coupling schedules. We discuss the SWMF architecture, physics and implementation of component coupling, and results of some preliminary simulations that involve all five components.

Optimal Adaptive Designs for Delayed Response Models: Exponential Case

We propose a delayed response model for a Bernoulli 2-armed bandit. Patients arrive according to a Poisson process and their response times are exponential. We develop optimal solutions, and compare to previously suggested designs.

Development of an atmospheric climate model with self-adapting grid and physics

An adaptive grid dynamical core for a global atmospheric climate model has been developed. Adaptations allow a smooth transition from hydrostatic to non-hydrostatic physics at small resolution. The adaptations use a parallel program library for block-wise adaptive grids on the sphere. This library also supports the use of a reduced grid with coarser resolution in the longitudinal direction as the poles are approached. This permits the use of a longer time step since the CFL number restriction (CFL < 1) in a regular longitude-latitude grid is most severe in the zonal direction at high latitudes. Several tests show that our modelling procedures are stable and accurate.