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New CCMC/SWRC Ensemble Modeling Improves Forecasts of CME Impacts throughout the Heliosphere


Mays, M. L., B. J. Thompson, L. K. Jian, R. C. Colaninno, D. Odstrcil, C. Möstl, M. Temmer, N. P. Savani, A. Taktakishvili, P. J. MacNeice, Y. Zheng (2015), Propagation of the 7 January 2014 CME and Resulting Geomagnetic Non-Event, Astrophysical Journal, 812, 145. doi:10.1088/0004-637X/812/2/145. [arXiv]

New Ensemble CME Modeling Products from the SWRC

Ensemble forecasting of coronal mass ejections (CMEs) provides significant information in that it provides an estimation of the spread or uncertainty in CME arrival time predictions due to uncertainties in determining CME input parameters. Ensemble modeling of CME propagation in the heliosphere is performed by forecasters at the Space Weather Research Center (SWRC) using the WSA-ENLIL cone model available at the Community Coordinated Modeling Center (CCMC). SWRC is an in-house research-based operations team at the CCMC which provides interplanetary space weather forecasting for NASA's robotic missions and performs real-time model validation. A distribution of n (routinely n=48) CME input parameters are generated using the CCMC Stereo CME Analysis Tool (StereoCAT) which employs geometrical triangulation techniques. These input parameters are used to perform n different simulations yielding an ensemble of solar wind parameters at various locations of interest (satellites or planets), including a probability distribution of CME shock arrival times (for hits), and geomagnetic storm strength (for Earth-directed hits). Ensemble simulations have been performed experimentally in real-time at the CCMC since January 2013. Some considerations for the accuracy of ensemble CME arrival time predictions include the importance of the initial distribution of CME input parameters, particularly the mean and spread. When the observed arrivals are not within the predicted range, this still allows the ruling out of prediction errors caused by tested CME input parameters. Prediction errors can also arise from ambient model parameters such as the accuracy of the solar wind background, and other limitations. Additionally the ensemble modeling setup was used to complete a parametric event case study of the sensitivity of the CME arrival time prediction to free parameters for ambient solar wind model and CME.

New beta ensemble products have been implemented starting Nov 20, 2013.

Click here for an example iSWA layout for a recent ensemble run. The first row of cygnets show the WSA-ENLIL+Cone model animation for the median ensemble member, the second row shows a histogram of arrival times at Earth, and the remaining cygnets show the WSA-ENLIL+Cone modeled density, velocity, magnetic field, and temperature at Earth.

Click here for an article about how the SWRC is providing the world's first ensemble space weather forecasting.

Mays, M. L., B. J. Thompson, L. K. Jian, R. C. Colaninno, D. Odstrcil, C. Möstl, M. Temmer, N. P. Savani, A. Taktakishvili, P. J. MacNeice, Y. Zheng (2015), Propagation of the 7 January 2014 CME and Resulting Geomagnetic Non-Event, Astrophysical Journal, 812, 145. doi:10.1088/0004-637X/812/2/145. [arXiv]