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Performance of Major Flare Watches from the Max Millennium Program (2001-2010)  

D. Shaun Bloomfield   Submitted: 2015-12-15 00:57

The physical processes that trigger solar flares are not well understood and significant debate remains around processes governing particle acceleration, energy partition, and particle and energy transport. Observations at high resolution in energy, time, and space are required in multiple energy ranges over the whole course of many flares in order to build an understanding of these processes. Obtaining high-quality, co-temporal data from ground- and space- based instruments is crucial to achieving this goal and was the primary motivation for starting the Max Millennium program and Major Flare Watch (MFW) alerts, aimed at coordinating observations of all flares >X1 GOES X-ray classification (including those partially occulted by the limb). We present a review of the performance of MFWs from 1 February 2001 to 31 May 2010, inclusive, that finds: (1) 220 MFWs were issued in 3,407 days considered (6.5% duty cycle), with these occurring in 32 uninterrupted periods that typically last 2-8 days; (2) 56% of flares >X1 were caught, occurring in 19% of MFW days; (3) MFW periods ended at suitable times, but substantial gain could have been achieved in percentage of flares caught if periods had started 24 h earlier; (4) MFWs successfully forecast X-class flares with a true skill statistic (TSS) verification metric score of 0.500, that is comparable to a categorical flare/no-flare interpretation of the NOAA Space Weather Prediction Centre probabilistic forecasts (TSS = 0.488).

Authors: D. Shaun Bloomfield, Peter T. Gallagher, William H. Marquette, Ryan O. Milligan, Richard C. Canfield
Projects: GOES X-rays

Publication Status: Solar Physics (in press)
Last Modified: 2015-12-15 09:30
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Toward Reliable Benchmarking of Solar Flare Forecasting Methods  

D. Shaun Bloomfield   Submitted: 2012-02-27 09:04

Solar flares occur in complex sunspot groups, but it remains unclearhow the probability of producing a flare of a given magnitude relatesto the characteristics of the sunspot group. Here, we useGeostationary Operational Environmental Satellite X-ray flares andMcIntosh group classifications from solar cycles 21 and 22 tocalculate average flare rates for each McIntosh class and use these todetermine Poisson probabilities for different flare magnitudes.Forecast verification measures are studied to find optimum thresholdsto convert Poisson flare probabilities into yes/no predictions ofcycle 23 flares. A case is presented to adopt the true skill statistic(TSS) as a standard for forecast comparison over the commonly usedHeidke skill score (HSS). In predicting flares over 24 hr, the maximumvalues of TSS achieved are 0.44 (C-class), 0.53 (M-class), 0.74(X-class), 0.54 (>=M1.0), and 0.46 (>=C1.0). The maximum values of HSSare 0.38 (C-class), 0.27 (M-class), 0.14 (X-class), 0.28 (>=M1.0), and0.41 (>=C1.0). These show that Poisson probabilities performcomparably to some more complex prediction systems, but the overallinaccuracy highlights the problem with using average values torepresent flaring rate distributions.

Authors: D. Shaun Bloomfield, Paul A. Higgins, R. T. James McAteer, and Peter T. Gallagher
Projects: None

Publication Status: Published in ApJL
Last Modified: 2012-02-29 08:25
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Performance of Major Flare Watches from the Max Millennium Program (2001-2010)
Toward Reliable Benchmarking of Solar Flare Forecasting Methods

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Max Millennium Flare Catalog

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