Report of Solar Geophysical Activity (RSGA)Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 266 Issued at 2200Z on 23 Sep 2013 IA. Analysis of Solar Active Regions and Activity from 22/2100Z to 23/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 5 numbered sunspot regions on the disk. IB. Solar Activity Forecast: Solar activity is likely to be low on days one, two, and three (24 Sep, 25 Sep, 26 Sep). IIA. Geophysical Activity Summary 22/2100Z to 23/2100Z: 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 425 km/s at 23/0304Z. Total IMF reached 5 nT at 23/0844Z. The maximum southward component of Bz reached -4 nT at 23/1643Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1893 pfu. IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet to unsettled levels on day one (24 Sep) and quiet levels on days two and three (25 Sep, 26 Sep). III. Event probabilities 24 Sep-26 Sep Class M 05/05/05 Class X 01/01/01 Proton 01/01/01 PCAF green IV. Penticton 10.7 cm Flux Observed 23 Sep 108 Predicted 24 Sep-26 Sep 108/108/108 90 Day Mean 23 Sep 111 V. Geomagnetic A Indices Observed Afr/Ap 22 Sep 006/007 Estimated Afr/Ap 23 Sep 005/005 Predicted Afr/Ap 24 Sep-26 Sep 008/008-004/005-004/005 VI. Geomagnetic Activity Probabilities 24 Sep-26 Sep A. Middle Latitudes Active 10/05/05 Minor Storm 01/01/01 Major-severe storm 01/01/01 B. High Latitudes Active 15/15/15 Minor Storm 25/15/15 Major-severe storm 10/05/05 Radio Events Observed 23 Sep 2013 A. 245 MHz Bursts Start End Peak Flux Time of Peak Duration 0007 0008 110 0007 0001 0024 0024 140 0024 0000 0136 0136 120 0136 0000 0141 0141 170 0141 0000 0143 0143 200 0143 0000 0145 0145 110 0145 0000 0203 0203 130 0203 0000 0227 0227 120 0227 0000 0247 0247 100 0247 0000 0255 0255 160 0255 0000 0310 0310 130 0310 0000 0323 0323 100 0323 0000 0547 0547 140 0547 0000 0759 0759 110 0759 0000 0805 0805 120 0805 0000 B. 245 MHz Noise Storms Start End Peak Flux Time of Peak 0549 0622 140 0603
For current space weather conditions please refer to:
http://www.swpc.noaa.gov/NOAAscales/index.html#SolarRadiationStorms NOAA Space Weather Scale descriptions can be found at www.sec.noaa.gov/NOAAscalesSolar Radio DataBackground 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. |