# Presentation: 660292

## The Solar Cycle 24 Consensus Prediction

- Douglas Biesecker (NOAA/SEC)
- and the Solar Cycle 24 Panel

## WHAT IS A SOLAR CYCLE?

- Solar activity rises and falls over an 11 year cycle
- Can be shorter/longer
- Activity correlates with
- Sunspot Number

## The Solar Cycle 24 Panel

- Charged with determining the official prediction for Solar Cycle 24 for NOAA, NASA, and the International Space Environment Service (ISES)
- Time and intensity of solar cycle 24
- Sunspot number
- F10.7
- Panel chaired by NOAA, funded by NASA
- Previous panels met in 1989 and 1996
- International membership
- The panel has 12 voting members
- Only 11 voted on these predictions

## The Panel

| Panelist | Affiliation | Panelist | Affiliation |
| --- | --- | --- | --- |
| D. Biesecker | NOAA, Chair | D. Pesnell | NASA |
| M. Dikpati | NCAR | M. Rast | U. Colorado |
| K. Dowdy | USAF | L. Svalgaard | ETK Inc. |
| D. Hathaway | NASA | R. Thompson | IPS Australia |
| T. Hoeksema | Stanford U. | R. Van der Linden | Royal Obs. Of Belgium |
| E. Kihn | NOAA | J. Kunches | NOAA,
ex-officio |
| H. Lundstedt | Swedish Inst. of Space Sci. | O.C. St. Cyr | NASA,
ex-officio |

## The Consultants

| Consultant | Affiliation | Consultant | Affiliation |
| --- | --- | --- | --- |
| P. Charbonneau | U. Montreal | K. Strong | Lockheed Martin |
| P. McIntosh | HelioSynoptics | A. Tlatov | Kislovodsk Solar Station, Russia
 |
| M. Penn | National Solar Observatory | S. Tobias | Leeds Univ., UK
 |
| J. Sanders | USAF | R. Ulrich | UCLA |

## The Panel is today releasing predictions for

- The impending solar minimum
- Marking onset of Cycle 24
- Provided basis for the other predictions
- The peak sunspot number expected for Cycle 24
- The time of the peak sunspot number
- What follows is the consensus of the panel

## Solar Minimum Prediction

**March, 2008** (±6 months)
- Marks the end of Cycle 23 and start of Cycle 24
- The length of Cycle 23 will then be 11.75 years
- due to the absence of expected signatures of minimum-like conditions in March, 2007
- no high-latitude sunspots yet observed with the Cycle 24 polarity
- the large scale corona has not yet relaxed to a simple dipole
- the heliospheric current sheet has not yet flattened
- activity measures, *e.g.* cosmic ray flux, radio flux, and sunspot number, have not yet reached typical solar minimum values

## Cycle 24 Maximum Prediction

- Will peak at a sunspot number of **140(****±20)** in **October, 2011  **(F10.7 = 187 sfu)
- Or
- Will peak at a sunspot number of **90(****±10)** in **August, 2012 **(F10.7 = 141 sfu)
**The panel is split!**
- The next cycle will be neither extreme, nor average

## The April 25 Prediction

## How split is the panel?

- Voting came out 6-5
- Favoring small
- Allowing voters to express their confidence in each prediction resulted in an even closer result
- 	5.8 to 5.2

## A few comments...

- Why the panel still disagrees...
- We’re still a long way from solar minimum
- 5-17 months based on panel prediction
- What’s the main difference between the big (140) and small (90) predictions?
- Big – assume solar memory lasts 20-30 years
- Small – assume solar memory lasts 11 years
- This is the view of the panel chair

## What to watch for...

- What would cause the big predictors to think small
- If solar minimum drags out beyond March, 2008
- What would cause the small predictors to think big
- If either the magnetic field at the sun’s poles increases in strength or geomagnetic activity increases before March, 2008

## There is still work to do...

- The panel will re-evaluate conditions on the sun every 3 months
- The panel will update this prediction annually, or as things change.

- The Panel chair wishes to thank, Susan Baltuch, Ellen Martinez, and Eron Brennan for their support of the panel workshops held at UCAR in Boulder
- NASA for providing the funding of this effort
- The panel members, for working hard and with a very good spirit