Joint USAF/NOAA Solar Geophysical Activity Report and Forecast
SDF Number 238 Issued at 2200Z on 26 Aug 2013
IA. Analysis of Solar Active Regions and Activity from 25/2100Z to
26/2100Z: Solar activity has been at very low levels for the past 24
hours. There are currently 3 numbered sunspot regions on the disk.
IB. Solar Activity Forecast: Solar activity is expected to be very low
with a chance for a C-class flares on days one, two, and three (27 Aug,
28 Aug, 29 Aug).
IIA. Geophysical Activity Summary 25/2100Z to 26/2100Z: The geomagnetic
field has been at quiet levels for the past 24 hours. Solar wind speed,
as measured by the ACE spacecraft, reached a peak speed of 399 km/s at
25/2104Z. Total IMF reached 5 nT at 26/1810Z. The maximum southward
component of Bz reached -3 nT at 26/2047Z. Electrons greater than 2 MeV
at geosynchronous orbit reached a peak level of 1951 pfu.
IIB. Geophysical Activity Forecast: The geomagnetic field is expected
to be at quiet levels on days one, two, and three (27 Aug, 28 Aug, 29
Aug).
III. Event probabilities 27 Aug-29 Aug
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 26 Aug 111
Predicted 27 Aug-29 Aug 105/100/100
90 Day Mean 26 Aug 114
V. Geomagnetic A Indices
Observed Afr/Ap 25 Aug 007/007
Estimated Afr/Ap 26 Aug 006/006
Predicted Afr/Ap 27 Aug-29 Aug 006/005-006/005-006/005
VI. Geomagnetic Activity Probabilities 27 Aug-29 Aug
A. Middle Latitudes
Active 10/10/10
Minor Storm 01/01/01
Major-severe storm 01/01/01
B. High Latitudes
Active 15/15/15
Minor Storm 15/15/15
Major-severe storm 10/10/10
CONTINUED ALERT: Electron 2MeV Integral Flux exceeded 1000pfu
Continuation of Serial Number: 2076
Begin Time: 2013 Aug 23 1500 UTC
Yesterday Maximum 2MeV Flux: 1952 pfu
NOAA Space Weather Scale descriptions can be found at
www.swpc.noaa.gov/NOAAscales
Potential Impacts: Satellite systems may experience significant charging resulting in increased risk to satellite systems.
Summary For August 19-25
No space weather storms were observed.
Outlook For August 26-September 1
No space weather storms are expected.
Radio Events Observed 26 Aug 2013
A. 245 MHz Bursts
No 245 MHz Burst Observed.
B. 245 MHz Noise Storms
No 245 MHz Noise Storms Observed.
NOAA Space Weather Scale descriptions can be found at
www.sec.noaa.gov/NOAAscales
Solar Radio Data
Background
Scientists monitor the structure of the solar corona, the outer
most regions of the Sun's atmosphere, using radio waves -- the surface
of the Sun is 6,000 degrees Kelvin, while the high corona can reach
several million degrees Kelvin. Solar radio emissions at different
frequencies allow us to observe radiation from different heights in
the atmosphere. The lower the frequency, the higher the height of
origin. The frequency, like the electron density, decreases uniformly
outwards: 245 MHz originates high in the corona, while 15,400 MHz
originates in the low corona. The 5 MHz emission corresponds to about
10 solar radii height. For a detailed review, see McLean and Labrum
(1985)SOLAR RADIOPHYSICS.
Radio bursts are associated with solar flares. The delay at Earth
of the different radio frequencies during burst events is due to the
outward movement of the source. Bursts can have temperatures of 10xE12
degrees Kelvin. Large bursts last 10 to 20 minutes on average. Longer
radio noise storms of persistent and variable high levels of radiation
originate in sunspot groups, areas of large, intense magnetic fields.
These storms are strongly circularly polarized due to the intense
magnetic fields.
http://www.ngdc.noaa.gov/stp/solar/solarradio.html
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