Academic Lecture: Towards a New Space Weather Modeling Suite

Topic : Towards a New Space Weather Modeling Suite
Speaker : ZHANG, Binzheng   Assistant Professor of Earth Sciences, University of Hong Kong
Time : 2:30pm-4:30pm   Tuesday, October 9, 2018
Place : 303 Conference Room in Electronic and Information School

Abstract : 
       It is now over three decades since the first paper was published using the code that has come to be known as LFM (Lyon-Fedder-Mobarry). The code, used since then extensively in heliophysics research, had a number of novel features: eighth-order centered spatial differencing, the Partial Donor Cell Method limiter for shock capturing, a non-orthogonal staggered spherical mesh with constrained transport, conservative averaging-reconstruction for axis singularities and the capability to handle multiple ion species. However the computational kernel of the LFM code, designed and optimized for architectures long retired, has aged and is difficult to adapt to the modern multicore era of supercomputing. To carry its legacy forward, we re-envisage the LFM as GAMERA, Grid Agnostic MHD for Extended Research Applications, which pre- serves the core numerical philosophy of LFM while also incorporating numerous algorithmic and computational improvements. The upgrades in the numerical schemes include accurate grid metric calculations using high-order Gaussian quadrature techniques, high-order upwind reconstruction, non-clipping options for interface values. The improvements in the code implementation includes the use of data structures and memory access patterns conducive to aligned, vector operations and the implementation of hybrid parallelism, using MPI and OMP. Thus, while keeping the best elements of LFM, GAMERA is designed to be a portable and easy-to-use code that provides multi-dimensional MHD simulations in non-orthogonal curvilinear geometries on modern super- computer architectures. The new, efficient and high-quality numerical kernel is currently serving as a backbone of a whole geospace model. Extended applications include magnetospheres of Jupiter/Saturn and Mercury/Venus, inner heliosphere, solar corona and a basic plasma physics simulation box.

About the speaker : 
     Within the broader field of geospace science, my main research focuses on system-level studies of the interaction between the solar wind, magnetosphere, ionosphere and upper atmosphere, including neutral dynamics, plasma electrodynamics, magnetohydrodynamics (MHD), and collisionless transport processes, with applications to space weather forecasting. I am also interested in the development of high-performance computing based, general purposed multi-dimensional models of solving the MHD equations for extended research applications, including but not limited to, geospace, planetary magnetospheres, inner heliosphere, solar corona and basic plasma simulations. 
     With my research collaborators, I am currently working on the development of a coupled whole geospace model for space weather research, simulation models for ionospheric outflows into the magnetosphere; the effects of magnetosphere-ionosphere coupling on the global geospace dynamics; the dynamics of co-rotation dominated magnetospheres such as Jupiter and Saturn; and high-order numerical schemes for solving the MHD equations.