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SPACE WEATHER PREDICTION:

Research and Development


``Space weather'' refers to the state of the magnetosphere and ionosphere which is determined by the solar wind. Under disturbed conditions, satellite- and ground-based technological systems, e.g., communications networks, electric power grids, and satellites, can suffer deleterious effects. Such systems are particularly vulnerable during severe geomagnetic storms. Large storms are relatively infrequent, but when they occur, they can stress the susceptible systems for prolonged periods of time over large geographic areas. Secure operation of systems can still be maintained and hazards can be minimized if the occurrence, duration, and severity of impending storms can be accurately predicted in a timely manner. Thus, space weather forecasting is important for protecting national assets in both the commercial and military sectors. This task is being carried out by the Space Environment Center (SEC) of the National Oceanic and Atmospheric Administration (NOAA) and the U. S. Air Force.

Accurate forecasts of large storms are difficult to achieve because the propagation of solar disturbances to the Earth is difficult to predict with high accuracy. A method of real-time prediction of large nonrecurrent geomagnetic storms is under development at the Plasma Physics Division, Naval Research Laboratory. Using the solar wind quantities measured upstream from the Earth as input, the algorithm recognizes the impending arrival of geoeffective solar wind structures and predicts their geoeffectiveness. The initial tests using historical solar wind data show that the current implementation of the method can accurately identify and predict the occurrence of large storms, with accuracy in the range of 70-80%. Warning time of several hours to more than 10-20 hours may be achieved, depending on the solar cycle.


Real-Time Prediction of Large Geomagnetic Storms


A joint product of the Plasma Physics Division, Naval Research Laboratory, the WIND MFI team of the NASA Goddard Space Flight Center, and the World Data Center C2 (WDC-C2) for Geomagnetism, Kyoto University, Japan.

Testing the Method

The real-time prediction method is currently undergoing testing. The algorithm requires solar wind data as input and calculates the probability that the solar wind being encountered presages the imminent arrival of a geoeffective structure resulting in a storm exceeding a specified threshold. The prediction output also includes the estimated duration (tau') and the maximum value (Bzm') of the Bz component of the geoeffective solar wind event.

In a real-time mode, a continuous stream of real-time solar wind data is required. At this time, such data are not available. We are conducting a comprehensive test of this method in its present form (as of March 1997) using the magnetic field data of the WIND MFI experiment according to a set of quantitative test criteria. The severity of storms is expressed in terms of the hourly Dst. The prediction results are compared with the Dst index published by the WDC, Kyoto University. Currently, it is anticipated that the results will be updated weekly. For the most recent results, Dst values may not be available. As soon as the provisional Dst becomes available, the prediction results and the provisional Dst values are compared. The latest results are shown below.


ACE Data

The algorithm to make predictions on a daily basis using the ACE data is being tested. The real-time ACE data are made available by the Space Environment Center (SEC). Some results of interest will be posted here from time to time. Click here.

Latest Prediction Results

INPUT: By and Bz of the solar wind (panels a and b) (WIND MFI data) ,(ACE SEC).
PREDICTION OUTPUT: tau', Bzm', and P1 (panels c, d, and e)
COMPARISON: Dst index (panel f) (WDC data)

Latest ACE Prediction

==== 25 Mar 2010 ====

New prediction including solar wind speed:

25 Mar

Latest WIND Prediction

==== 14 Mar - 20 Mar 2010 (DOY 073 - 079) ====

Weekly ACE Prediction

==== 14 Mar - 20 Mar 2010 (DOY 073 - 079) ====

What the Figure Shows

The magnetic field vector components are given in the GSM (Geocentric Solar Magnetosphere) coordinate system, with x pointing toward the Sun from the Earth, y in the east-west direction, and z pointing north. The solar wind (SW) is thought of as consisting of a series of events. Each event is defined to be the SW between successive times when Bz changes sign. Each event is characterized by two quantities: (1) tau=duration of the event and (2) Bzm=maximum Bz value (positive or negative) during the event. In the present version of the algorithm, we use only Bz (panel b) as the primary input supplemented by By (panel a). The input is the 5-minute average of the WIND MFI data. For each event being encountered, the duration and maximum Bz value are predicted at each time step. These are given in panels (c) and (d), where the primed symbols (tau' and Bzm') are quantities estimated by using the SW data available up to the time of prediction. tau' is measured from the beginning of the event (Tz), i.e., the last time when Bz = 0. The output of the pediction algorithm at each time step is the probability P1, given in panel (e), that a the event being encountered is geoeffective (threshold: Dst < -80 nT for two hours or longer) with the estimated duration (tau') and maximum Bz (Bzm'). For the purpose of the test, if P1 (solid line) exceeds 0.5 for 2 hours or more, it is regarded as a positive prediction. If a storm with Dst below the -80 nT threshold occurs, the prediction is correct. Presently, the duration of the storm is not predicted. Even if no geoeffective SW event is encountered, P1 can exhibit spikes but should not exceed 0.5 for 2 hours or more. The prediction output (P1) is compared with the actual, provisional, or quick-look Dst index provided by the WDC-C2 (Kyoto University). In addition, the predicted tau' (panel c) and Bzm' (panel d) can be compared with the actual SW input data (panels a and b). Hits, misses, and false alarms are tabulated below.

NOTE: Occasionally, the WIND spacecraft is moved out of the solar wind into the magnetosphere. When they occur, such periods are designated "Non-IMF" and are bracketed by vertical lines (and shaded in panels a and b). The prediction results during such periods are not meaningful.

DISCUSSION OF THE LATEST RESULTS

.
HOW TO INTERPRET PANEL (e) -- In showing the results (P1) of the Bayesian classification algorithm, several different situations are distinguished by line style.
Solid line:
  Probability that the event being encountered is geoeffective 
  (Dst < -80 nT) with the estimated values of tau' and Bzm'.  
  (Typically, P1 = 0 unless Bzm' < 0.)

Dashed line:
  Probability that the event, having Bzm' > 0, is not geoeffective but 
  will be immediately followed by a geoeffective event of comparable tau' 
  and Bzm' < 0. The time until the predicted southward turning of Bz is 
  equal to [tau' - (present time - Tz)], where Tz is the beginning of the 
  event.  Dashed lines occur only when Bzm' > 0 with long predicted 
  duration and may be interpreted as "storm watches."  
  See DOY 185 below for an example.

Dotted line:
  Probability that the current event is a long-duration nongeoeffective 
  (Bzm' > 0) event and will not be immediately followed by a geoeffective 
  event of comparable tau' and Bzm' < 0.

Previous Results

Earlier results are archived and can be accessed by clicking on the desired time periods listed below.

Last 5 Days (ACE):

24 Mar

23 Mar

22 Mar

21 Mar

20 Mar

Last 5 Weeks:

07 Mar - 13 Mar 2010 (DOY 066 - 072)

28 Feb - 06 Mar 2010 (DOY 059 - 065)

21 Feb - 27 Feb 2010 (DOY 052 - 058)

14 Feb - 20 Feb 2010 (DOY 045 - 051)

07 Feb - 13 Feb 2010 (DOY 038 - 044)

Monthly (WIND):

2010

1 Feb - 28 Feb 2010 (DOY 032 - 059)

1 Jan - 31 Jan 2010 (DOY 001 - 031)

2009

1 Dec - 31 Dec 2009 (DOY 335 - 365)

1 Nov - 30 Nov 2009 (DOY 305 - 334)

1 Oct - 31 Oct 2009 (DOY 274 - 304)

1 Sep - 30 Sep 2009 (DOY 244 - 273)

1 Aug - 31 Aug 2009 (DOY 213 - 243)

1 Jul - 31 Jul 2009 (DOY 182 - 212)

1 Jun - 30 Jun 2009 (DOY 152 - 181)

1 May - 31 May 2009 (DOY 121 - 151)

1 Apr - 30 Apr 2009 (DOY 091 - 120)

1 Mar - 31 Mar 2009 (DOY 060 - 090)

1 Feb - 28 Feb 2009 (DOY 032 - 059)

2008

1 Dec - 31 Dec 2008 (DOY 336 - 366)

1 Nov - 30 Nov 2008 (DOY 306 - 335)

1 Oct - 31 Oct 2008 (DOY 275 - 305)

1 Sep - 30 Sep 2008 (DOY 245 - 274)

1 Aug - 31 Aug 2008 (DOY 214 - 244)

1 Jul - 31 Jul 2008 (DOY 183 - 213)

1 Jun - 30 Jun 2008 (DOY 153 - 182)

1 May - 31 May 2008 (DOY 122 - 152)

1 Apr - 30 Apr 2008 (DOY 092 - 121)

1 Mar - 31 Mar 2008 (DOY 061 - 091)

1 Feb - 29 Feb 2008 (DOY 032 - 060)

1 Jan - 31 Jan 2008 (DOY 001 - 031)

2007

1 Dec - 31 Dec 2007 (DOY 335 - 365)

1 Nov - 30 Nov 2007 (DOY 305 - 334)

1 Oct - 31 Oct 2007 (DOY 274 - 304)

1 Sep - 30 Sep 2007 (DOY 244 - 273)

1 Aug - 31 Aug 2007 (DOY 213 - 243)

1 Jul - 31 Jul 2007 (DOY 182 - 212)

1 Jun - 30 Jun 2007 (DOY 152 - 181)

1 May - 31 May 2007 (DOY 121 - 151)

1 Apr - 30 Apr 2007 (DOY 091 - 120)

1 Mar - 31 Mar 2007 (DOY 060 - 090)

1 Feb - 28 Feb 2007 (DOY 032 - 059)

1 Jan - 31 Jan 2007 (DOY 001 - 031)

2006

1 Dec - 31 Dec 2006 (DOY 335 - 365)

1 Nov - 30 Nov 2006 (DOY 305 - 334)

1 Oct - 31 Oct 2006 (DOY 274 - 304)

1 Sep - 30 Sep 2006 (DOY 244 - 273)

1 Aug - 31 Aug 2006 (DOY 213 - 243)

1 Jul - 31 Jul 2006 (DOY 182 - 212)

1 Jun - 30 Jun 2006 (DOY 152 - 181)

1 May - 31 May 2006 (DOY 121 - 151)

1 Apr - 30 Apr 2006 (DOY 091 - 120)

1 Mar - 31 Mar 2006 (DOY 060 - 090)

1 Feb - 28 Feb 2006 (DOY 032 - 059)

1 Jan - 31 Jan 2006 (DOY 001 - 031)

2005

1 Dec - 31 Dec 2005 (DOY 335 - 365)

1 Nov - 30 Nov 2005 (DOY 305 - 334)

1 Oct - 31 Oct 2005 (DOY 274 - 304)

1 Sep - 30 Sep 2005 (DOY 244 - 273)

1 Aug - 31 Aug 2005 (DOY 213 - 243)

1 Jul - 31 Jul 2005 (DOY 182 - 212)

1 Jun - 30 Jun 2005 (DOY 152 - 181)

1 May - 31 May 2005 (DOY 121 - 151)

1 Apr - 30 Apr 2005 (DOY 091 - 120)

1 Mar - 31 Mar 2005 (DOY 060 - 090)

1 Feb - 28 Feb 2005 (DOY 032 - 059)

1 Jan - 31 Jan 2005 (DOY 001 - 031)

2004

1 Dec - 31 Dec 2004 (DOY 336 - 366)

1 Nov - 30 Nov 2004 (DOY 306 - 335)

1 Oct - 31 Oct 2004 (DOY 275 - 305)

1 Sep - 30 Sep 2004 (DOY 245 - 274)

1 Aug - 31 Aug 2004 (DOY 214 - 244)

1 Jul - 31 Jul 2004 (DOY 183 - 213)

1 Jun - 30 Jun 2004 (DOY 153 - 182)

1 May - 31 May 2004 (DOY 122 - 152)

1 Apr - 30 Apr 2004 (DOY 092 - 121)

1 Mar - 31 Mar 2004 (DOY 061 - 091)

1 Feb - 29 Feb 2004 (DOY 032 - 060)

1 Jan - 31 Jan 2004 (DOY 001 - 031)

2003

1 Dec - 31 Dec 2003 (DOY 335 - 365)

1 Nov - 30 Nov 2003 (DOY 305 - 334)

1 Oct - 31 Oct 2003 (DOY 274 - 304)

1 Sep - 30 Sep 2003 (DOY 244 - 273)

1 Aug - 31 Aug 2003 (DOY 213 - 243)

1 Jul - 31 Jul 2003 (DOY 182 - 212)

1 Jun - 30 Jun 2003 (DOY 152 - 181)

1 May - 31 May 2003 (DOY 121 - 151)

1 Apr - 30 Apr 2003 (DOY 091 - 120)

1 Mar - 31 Mar 2003 (DOY 060 - 090)

1 Feb - 28 Feb 2003 (DOY 032 - 059)

1 Jan - 31 Jan 2003 (DOY 001 - 031)

2002

1 Dec - 31 Dec 2002 (DOY 335 - 365)

1 Nov - 30 Nov 2002 (DOY 305 - 334)

1 Oct - 31 Oct 2002 (DOY 274 - 304)

1 Sep - 30 Sep 2002 (DOY 244 - 273)

1 Aug - 31 Aug 2002 (DOY 213 - 243)

1 Jul - 31 Jul 2002 (DOY 182 - 212)

1 Jun - 30 Jun 2002 (DOY 152 - 181)

1 May - 31 May 2002 (DOY 121 - 151)

1 Apr - 30 Apr 2002 (DOY 091 - 120)

1 Mar - 31 Mar 2002 (DOY 060 - 090)

1 Feb - 28 Feb 2002 (DOY 032 - 059)

1 Jan - 31 Jan 2002 (DOY 001 - 031)

2001

1 Dec - 31 Dec 2001 (DOY 335 - 365)

1 Nov - 30 Nov 2001 (DOY 305 - 334)

1 Oct - 31 Oct 2001 (DOY 274 - 304)

1 Sep - 30 Sep 2001 (DOY 244 - 273)

1 Aug - 31 Aug 2001 (DOY 213 - 243)

1 Jul - 31 Jul 2001 (DOY 182 - 212)

1 Jun - 30 Jun 2001 (DOY 152 - 181)

1 May - 31 May 2001 (DOY 121 - 151)

1 Apr - 30 Apr 2001 (DOY 091 - 120)

1 Mar - 31 Mar 2001 (DOY 060 - 090)

1 Feb - 28 Feb 2001 (DOY 032 - 059)

1 Jan - 31 Jan 2001 (DOY 001 - 031)

2000

1 Dec - 31 Dec 2000 (DOY 336 - 366)

1 Nov - 30 Nov 2000 (DOY 306 - 335)

1 Oct - 31 Oct 2000 (DOY 275 - 305)

1 Sep - 30 Sep 2000 (DOY 245 - 274)

1 Aug - 31 Aug 2000 (DOY 214 - 244)

1 Jul - 31 Jul 2000 (DOY 183 - 213)

1 Jun - 30 Jun 2000 (DOY 153 - 182)

1 May - 31 May 2000 (DOY 122 - 152)

1 Apr - 30 Apr 2000 (DOY 092 - 121)

1 Mar - 31 Mar 2000 (DOY 061 - 091)

1 Feb - 29 Feb 2000 (DOY 032 - 060)

1 Jan - 31 Jan 2000 (DOY 001 - 031)

1999

1 Dec - 31 Dec 1999 (DOY 335 - 365)

1 Nov - 30 Nov 1999 (DOY 305 - 334)

1 Oct - 31 Oct 1999 (DOY 274 - 304)

1 Sep - 30 Sep 1999 (DOY 244 - 273)

1 Aug - 31 Aug 1999 (DOY 213 - 243)

1 Jul - 31 Jul 1999 (DOY 182 - 212)

1 Jun - 30 Jun 1999 (DOY 152 - 181)

1 May - 31 May 1999 (DOY 121 - 151)

1 Apr - 30 Apr 1999 (DOY 91 - 120)

1 Mar - 31 Mar 1999 (DOY 60 - 90)

1 Feb - 28 Feb 1999 (DOY 32 - 59)

1 Jan - 31 Jan 1999 (DOY 1 - 31)

1998

1 Dec - 31 Dec 1998 (DOY 335 - 365)

1 Nov - 30 Nov 1998 (DOY 305 - 334)

1 Oct - 31 Oct 1998 (DOY 274 - 304)

1 Sep - 30 Sep 1998 (DOY 244 - 273)

1 Aug - 31 Aug 1998 (DOY 213 - 243)

1 Jul - 31 Jul 1998 (DOY 182 - 212)

1 Jun - 30 Jun 1998 (DOY 152 - 181)

1 May - 31 May 1998 (DOY 121 - 151)

1 Apr - 30 Apr 1998 (DOY 91 - 120)

1 Mar - 31 Mar 1998 (DOY 60 - 90)

1 Feb - 28 Feb 1998 (DOY 32 - 59)

1 Jan - 31 Jan 1998 (DOY 1 - 31)

1997

1 Dec - 31 Dec 1997 (DOY 335 - 365)

1 Nov - 30 Nov 1997 (DOY 305 - 334)

1 Oct - 31 Oct 1997 (DOY 274 - 304)

1 Sep - 30 Sep 1997 (DOY 244 - 273)

1 Aug - 31 Aug 1997 (DOY 213 - 243)

1 Jul - 31 Jul 1997 (DOY 182 - 212)

1 Jun - 30 Jun 1997 (DOY 152 - 181)

1 May - 31 May 1997 (DOY 121 - 151)

1 Apr - 30 Apr 1997 (DOY 91 - 120)

1 Mar - 31 Mar 1997 (DOY 60 - 90)

1 Feb - 28 Feb 1997 (DOY 32 - 59)

1 Jan - 31 Jan 1997 (DOY 1 - 31)

1996

1 Dec - 31 Dec 1996 (DOY 336 - 366)

1 Nov - 3O Nov 1996 (DOY 306 - 335)

1 Oct - 31 Oct 1996 (DOY 275 - 305)

1 Sep - 30 Sep 1996 (DOY 245 - 274)

1 Aug - 31 Aug 1996 (DOY 214 - 244)

1 Jul - 31 Jul 1996 (DOY 183 - 213)

1 Jun - 30 Jun 1996 (DOY 153 - 182)

1 May - 31 May 1996 (DOY 122 - 152)

1 Apr - 30 Apr 1996 (DOY 92 - 121)

1 Mar - 31 Mar 1996 (DOY 61 - 91)

1 Feb - 29 Feb 1996 (DOY 32 - 60)

1 Jan - 31 Jan 1996 (DOY 1 - 31)

1978

1978 Data

Performance Characteristics

The performance characteristics of the current version (March 1997) are tabulated below.

  1. The probability distribution functions (PDFs) are constructed using the OMNI data set from 1973 to 1981. The storms in the last 5 months of 1978 are excluded because they were used to test the algorithm [Chen et al., 1997].

  2. The input: By and Bz components of the interplanetary magnetic field (IMF).

  3. The algorithm seeks to identify long-duration southward Bz structures but does not look for high-speed solar wind streams. It is expected that there will be more misses near solar minimum.

  4. Test criteria :
    Geoeffective: produces storm with Dst < -80 nT for 2 hours or longer
    Positive prediction: P1 > 0.5 for 2 hours or longer

  5. HITS, MISSES, STORM WATCHES, AND FALSE ALARMS
     
       1 January 1998 - 31 Mar 1998 
           Hits:          2 (DOY: 48, 69) 
           Misses:        0
           Storm Watches: 0
           False Alarms:  0
     
       1 January 1997 - 31 December 1997
           Hits:          6 (DOY: 10, 135, 159, 246, 327, 364)
           Misses:        3 (DOY: 111,284,311)
           Storm Watches: 2 (DOY: 185, 265)
           False Alarms:  1 (DOY: 344/345)
          *Storm on DOY 274 occurred while WIND was out of the IMF
    
       1 January 1996 - 31 December 1996
           Hits*:         0
           Misses:        1 (DOY: 297)
           Storm Watches: 0
           False Alarms:  0
          *Storm on DOY 13 occurred while WIND was out of the IMF
    
       1 January 1995 - 31 December 1995 -- coming soon
    
       1978 DOY 225-365 (Click here to see the 1978 results.)
           Hits:          5  (DOY: 240, 272, 300, 303, 329)
           Misses:        1  (DOY: 316)
           Storm Watches: 0
           False Alarms:  1  (DOY: 268)
    
       Cumulative:
           Hits:          13
           Misses:         5
           Storm Watches:  2
           False Alarms:   2
           No. Large Storms (hits + misses) = 18
    
    Note: A storm watch, shown by dashed lines for P1 [panel (e) above], 
          is included only if no storm follows - a misclassification 
          that does not lead to an "alarm" (solid lines).
    
  6. FAILURE MODES - Several failure modes have been identified to date. The following situations tend to cause misses: (1) long-duration southward Bz periods interrupted by short Bz > 0 periods; (2) large storms caused by weak magnetic clouds following periods of moderate (e.g., -80 nT < Dst < -40 nT); (3) storms primarily caused by high-speed solar wind. So far, during this solar cycle minimum period, incorrect predictions have been mainly for "marginal" storms, those with minimum Dst values in the vicinity of the threshold of Dst = -80 nT.

  7. EXAMPLES - Some examples of hits, misses, and false alarms are given and discussed. Click here .

  8. For a list of periods since 1995 when the Dst was less than -80 nT for at list 2 hours, click here .

Future Work

We expect to analyze misses and false alarms in detail to better understand the performance characteristics of the methods. A number of improvements are being developed to deal with the known failure modes, and as they are incorporated, we will update this web page to include descriptions and discussions. We expect to extend the method to analyze solar wind particle data in the near future. A real-time version of the algorithm is under development. When it is completed, it will be tested using the real-time solar wind data obtained by the Advanced Composition Explorer (ACE) satellite.


Please Note ...

The content of this web site is the product of the combined work of the three groups. The use of the WIND MFI data and the Dst index is for demonstration. The results of the prediction algorithm have not been generated as predictions in real-time. We welcome comments, suggestions, and criticisms. If you are interested in publishing any part of this web page, please contact the appropriate team.