High-Resolution Space-Weather Model, 15-9146Printer Friendly Version
Inclusive Dates: 07/01/99 - Current
Background - The term 'space-weather' refers to conditions on the sun, in the solar wind, magnetosphere, ionosphere, thermosphere, and mesosphere, that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health. A goal of the National Space Weather Program is to produce weather forecasts for the entire region of space ranging from the sun to the Earth's middle atmosphere. Currently simpler models exist that can simulate individual parts of the system; however, the goal of forecasting the entire system is still several years away. Analogous with meteorology, various advances are needed, including: speeding up of the models, models with higher resolution, data assimilation, and the ability to forecast the inputs that drive the models. The Institute has developed a parallelized model of the 30- to 500-km altitude region including the mesosphere, thermosphere, and ionosphere. In this internal research project, the research team seeks to improve the performance and accuracy of the existing model.
Approach - The new model is based on the experience gained in development of the SwRI parallelized thermosphere-ionosphere-mesosphere-electrodynamics (TIMEGCM) model and will also span the mesosphere, ionosphere, and thermosphere. The goal here is to address performance issues and model accuracy by implementing a patched-overset grid capability that is different from the structure of the existing model. The model will contain the same physics and chemistry as the earlier model. In this approach, a base grid is constructed using patched grid blocks, in which the grid resolution in each block is uniform but potentially different than that in adjacent blocks. Interpolation functions then define the relationship of flow parameters across the patched interface of adjoining grid blocks. The dynamic variation of this approach is called overset grids. A hierarchy of overlying grid systems dynamically moves through the base grid and may have significantly finer grid resolutions than the base grid system. A secondary goal of the proposed work is to improve the input specification to the model by using the assimilative mapping of ionospheric electrodynamics technique to provide realistic high latitude inputs.
Accomplishments - The new model is called ASPEN-2001 (for Advanced SPace Environment Model). A strategy has been devised for developing the new model, and coding has begun. A flow diagram of the new model has been constructed, breaking it into three major areas: input, dynamics/chemistry, and output. Coding has started on the input section. The goal is to establish three-dimensional structures instead of the two-dimensional structures used in the former model. The new model does not use restrictive structures such as common blocks and EQUIVALENCE statements, and all information needed by subroutines is passed by calling arguments. This methodology is convenient because each time the arguments are passed they result in a "message" in the context of parallelization. A test and validation procedure has been developed, and documentation of the physics and chemistry for the code has been initiated.