What is CGEM? Coronal Global Evolutionary Model or CGEM is a NASA/NSF funded Project between UC Berkeley, Stanford University and Lockheed Martin Space and Astrophysics Laboratory.
What is CGEM’s Goal? CGEM’s goal is to improve our understanding of the corona of the Sun — to develop and evaluate a model for the evolution of its magnetic field.
Why do CGEM? The most violent space weather events such as eruptive solar flares and coronal mass ejections are driven by the release of free magnetic energy stored in the solar corona. Once released this energy propagates through interplanetary space, frequently impacting the Earth’s space environment. How this energy is stored? This is a fundamental question to predict space weather. Yet current data-driven space-weather models have been unable to realistically answer that.
- Recent launch of SDO/HMI makes the data necessary to construct better coronal models regularly available
- Recent theoretical developments make it possible to derive electric fields from HMI data sequences using Faraday’s law and Doppler data
- Recent computational methods for evolving the coronal magnetic field using a magneto-frictional model make it practical to evolve the coronal magnetic field on spatial and temporal scales that are useful
- Develop enhanced processing and analysis of vector magnetic field and Doppler velocity data taken with the HMI instrument on NASA’s SDO Mission
- Use these processed data to derive the electric field in the solar photosphere (NOAA 11158 dataset)
- Using the photospheric magnetic and electric field vectors, evolve the overlying coronal magnetic field, using a ‘magnetofrictional’ model for its quasi-static evolution as energy builds up
- For magnetic field configurations that become unstable, use MHD models to evolve the solar corona, using output from the magnetofrictional model as an initial condition. For parts of the Sun for which no magnetic field data are available, a flux transport model will be developed and used to estimate the evolution of the magnetic and electric fields for the global version of the magnetic field model discussed below.