Major Flare Watch Evaluation

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(Statistics for Daily Major Flare Watch Messages)
(Statistics for Daily Major Flare Watch Messages)
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[[Image:MFW_Stats.jpg|frameless|center|thumb|500px|'''Table 1:''' Number of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, MFWs below) during the period 26-Mar-2001 to 17-May-2010 ]]
[[Image:MFW_Stats.jpg|frameless|center|thumb|500px|'''Table 1:''' Number of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, MFWs below) during the period 26-Mar-2001 to 17-May-2010 ]]
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It helps to look at these results in graphical form:
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In graphical form, these results show that the percentage of all flares caught by the MM_COs saturates at about 75% in the X-class range.
[[Image:mmco_percent.jpeg|frameless|center|thumb|500px|'''Figure 1:''' Percentage of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, aka MFWs) for 26-Mar-2001 to 17-May-2010 ]]
[[Image:mmco_percent.jpeg|frameless|center|thumb|500px|'''Figure 1:''' Percentage of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, aka MFWs) for 26-Mar-2001 to 17-May-2010 ]]
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== Summary ==
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Gamma-ray flares are a high-value target.  
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For reasons evident in Figure 1, let's identify them with GOES class > X1 (~ Shih 2009).   
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The data show that 220 MFW days were called over 9-plus years.  
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About 75% of all > X1 flares were caught at the cost of < 7% of all available observing days.  

Revision as of 18:47, 9 November 2010

Contents

Introduction

Flares that produce gamma-ray lines are the highest priority target of the RHESSI Mission. Multi-wavelength imaging and spectroscopic observations from other spacecraft and ground-based observatories before, during and after such flares are crucial to the interpretation or the RHESSI data. To optimize such observations, the Max Millennium Chief Observers (MM_COs) [1] announce a Major Flare Watch when the probability of gamma-ray-producing flares is high. Such announcements [2] appear in the Max Millennium Messages of the Day [3], distributed worldwide to over 200 solar observers and mission operations planners through the self-subscribing MMmmotd mailing list and archive [4]. How well has this system worked? That's the subject of this Nugget.

Major Flare Watch Criteria

Throughout the RHESSI mission, the MM_COs have used a set of Major Flare Watch criteria that are an outgrowth of the classic "BEARALERTS - A Successful Flare Prediction System" [5] paper by Zirin and Marquette (1991):

Statistics for Daily Major Flare Watch Messages

We've had a look at all GOES X-ray flares recorded in the daily NOAA/NWS Space Weather Prediction Center events files from 26-Mar-2001 to 17-May-2010, inclusive. We then extracted the number of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times. The total number of flares at or above the same GOES class is extracted from the complete time range under consideration (26-Mar-2001 to 17-May-2010) allowing the percentage to be calculated. We also extract the number of flares found within each of the 220 MFW 24 hour periods, so the number of MFW messages that both successfully and unsuccessfully catch flares is extracted and the percentage of MFW messages which are successful is calculated.

Table 1: Number of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, MFWs below) during the period 26-Mar-2001 to 17-May-2010

In graphical form, these results show that the percentage of all flares caught by the MM_COs saturates at about 75% in the X-class range.

Figure 1: Percentage of flares at or above a chosen GOES class within 24 hours of the Major Flare Watch UTC message issue times (24-hour MFW periods, aka MFWs) for 26-Mar-2001 to 17-May-2010

Summary

Gamma-ray flares are a high-value target.   For reasons evident in Figure 1, let's identify them with GOES class > X1 (~ Shih 2009).    The data show that 220 MFW days were called over 9-plus years.   About 75% of all > X1 flares were caught at the cost of < 7% of all available observing days.  

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