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May 8, 2009
Solar Cycle 24 Prediction Update
May 8, 2009 -- The Solar Cycle 24 Prediction Panel has reached a consensus
decision on the prediction of the next solar cycle (Cycle 24). First, the panel
has agreed that solar minimum occurred in December, 2008. This still qualifies
as a prediction since the smoothed sunspot number is only valid through
September, 2008. The panel has decided that the next solar cycle will be below
average in intensity, with a maximum sunspot number of 90. Given the predicted
date of solar minimum and the predicted maximum intensity, solar maximum is now
expected to occur in May, 2013. Note, this is a consensus opinion, not a
unanimous decision. A supermajority of the panel did agree to this prediction.
==============================================================================
==============================================================================
Recent Changes to Solar Cycle Values and Plots
March 2, 2009 -- The Solar Cycle 24 Prediction Panel has not issued any updates
to their prediction. However, the Space Weather Prediction Center, and the
Chair of the Prediction Panel decided to implement what they believe to be an
obvious change to the plotted data. The two predictions, of maximum being
either a SSN of 90 or a SSN of 140 remain intact. Once the date of solar
minimum is known, that is all the information needed to arrive at a prediction
curve. The panel prediction of solar minimum in March, 2008 has been eclipsed.
Minimum will now occur no earlier than August, 2008. For every month beyond
March 2008 that minimum slips, it is necessary to shift the prediction curves
by the same amount. SWPC commenced doing so in mid-February and will continue
to do so, unless or until the prediction panel sets a new predicted date for
the time of solar minimum.
==============================================================================
==============================================================================
ISES Solar Cycle Progression and Prediction Displays
An initial ISES Solar Cycle 24 Prediction was released in April, 2007.
At that time, the panel charged with determining the prediction was unable
to agree on a single solution and provided two predictions. As of May, 2009
the panel has reached consensus on a single prediction for Solar Cycle 24.
It is the lower of the two predictions previously issued. The prediction
can be accessed from the file Predict.txt, described below.
The solar cycle text and graphic files track the Solar Cycle
progression. The same data and plots appear in SWPC's "Weekly"
publication in Adobe format at URL:
http://www.swpc.noaa.gov/weekly/
UPDATE SCHEDULE:
The Solar Cycle products are updated once a month and are
put on-line the first Tuesday after the new values are available.
The latest values are usually available on the 3rd of every month.
TERMS AND DEFINITIONS:
Observed numbers are simple averages of the daily values for the month.
SWO Sunspot Numbers are issued by the NOAA Space Weather Prediction
Center (SWPC) in Boulder Colorado, USA.
The official International Sunspot Number (RI) is issued by the Sunspot
Index Data Center (SIDC) in Brussels, Belgium. Data and plots are available
from the SIDC web site at http://sidc.oma.be
10.7cm Radio Flux is the preliminary observed value measured in
Penticton, B.C. Canada. The values are displayed in solar flux units
(1 sfu = 10^-22 W/m^2/Hz).
The Ap Geomagnetic Index is the preliminary estimate calculated
by the United States Air Force (USAF).
For daily values, see http://www.swpc.noaa.gov/ftpmenu/indices.html
Daily Solar Data -- last 30 days
Daily Solar Data -- current quarter
Solar, Particle, and Geomag. Indices beginning Jan. 1994
Smooth values are an average of 13 monthly observed values centered on
the month of concern (the 1st and 13th months are given a weight of 0.5).
Ap(avg)=(0.5*Ap(1) +1.0*Ap(2) +1.0*Ap(3)+ ... +1.0*Ap(12) +0.5*Ap(13))/12.0
SWPC products use preliminary values. Final values are available through
the National Geophysical Data Center (NGDC) at http://www.ngdc.noaa.gov/
normally one to two months later.
CONTENTS:
This directory contains the following tabular lists:
a) Predict.txt - Predictions of SIDC sunspot number and 10.7cm
radio flux. This table contains the prediction issued by the ISES prediction
panel for solar cycle 24. Also given are error bars indicating the uncertainty
in the prediction. The table runs from the most current prediction through
January 2016. Because the predictions are for 13-month running smoothed
values, the first entry is always six months behind the issue date. High
and low bounds to the forecast are also provided.
b) RecentIndices.txt -
Recent Solar Indices (Preliminary)
of Observed Monthly Mean Values
The table includes the monthly averages and 13-month running smoothed values
from January 1991 to the present for:
SWO and SIDC sunspot numbers, and the ratio between the two,
10.7cm radio flux, and Estimated Planetary Ap.
Note: The August 2008 Sunspot number ratio (RI/SW) was minus 1 (-1).
The observed RI number was 0.5 and the SWO number was 0.0 which made
the RI/SW ratio a divide by 0. RI and SWO numbers are not calculated in
the same way. SWO has a non-zero sunspot number only if there was a
numbered active region on the disk. SIDC, the official home for RI sunspot
numbers, does not have this same requirement.
c) Predict_low.txt - This file still exists, but there is no longer a
link provided from a web page. It now contains fill data indicating invalid
data. Previously, it contained the lower than average prediction for Solar
Cycle 24 that was released in April, 2007.
d) Predict_high.txt - This file still exists, but there is no longer a
link provided from a web page. It now contains fill data indicating invalid
data. Previously, it contained the higher than average prediction for Solar
Cycle 24 that was released in April, 2007.
The following plots are available:
a) sunspot.gif - ISES Solar Cycle Sunspot Number Progression. This
plot displays SIDC monthly sunspot numbers, SIDC 13-month running smoothed
sunpot numbers, and the most recent forecasts for the low and high predictions.
b) f10.gif - ISES Solar Cycle F10.7cm Radio Flux Progression. This
plot displays monthly Penticton 10.7 cm Radio Flux values, 13-month
running smoothed values, and the most recent forecasts for the low and
high predictions.
c) Ap.gif - ISES Solar Cycle Ap Progression. This plot displays
monthly average Ap values and 13-month running smoothed Ap values. The most
recent data are always USAF estimates; offical values are included as they
become available.
Alternative Solar Cycle Plots are available at:
http://solarscience.msfc.nasa.gov/predict.shtml and
http://sidc.oma.be/sunspot-index-graphics/sidc_graphics.php
http://www.ips.gov.au/Solar/1/6
Please send questions and comments to SWPC.Webmaster@noaa.gov
.