A polar cap absorption event results from the ionisation of the D-layer of the polar
ionosphere by high energy protons. A PCA causes a HF radio blackout for trans polar
circuits and can last several days. PCAs are almost always preceded by a major solar
flare with the time between the flare event and the onset of the PCA ranging from few
minutes to several hours.
Real Time Riometer Data from Antarctic Stations
The icon below indicates the estimated absorption in db of a 30 MHz riometer from Casey
station in Antarctica. These figures give an indication of the severity of the PCA.
The background colour of the icon is red when absorption exceeds 1db and green otherwise.
Details of any current proton event are given below:
Last updated 02 Sep 2010 22:20 UT
| 10Mev Proton/PCA Event Began 22 08 2005 2100UT and is in progress
10Mev Proton/PCA Event Ended 25 08 2005 0140UT
10Mev Proton/PCA Event Began 08 09 2005 0235UT and is in progress
10Mev Proton/PCA Event Ended 13 09 2005 0025UT
10Mev Proton/PCA Event Began 14 09 2005 0100UT and is in progress
10Mev Proton/PCA Event Ended 16 09 2005 0025UT
10Mev Proton/PCA Event Began 06 12 2006 1625UT and is in progress
10Mev Proton/PCA Event Ended 12 12 2006 1135UT
10Mev Proton/PCA Event Began 13 12 2006 0305UT and is in progress
10Mev Proton/PCA Event Ended 15 12 2006 1645UT
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 | Last updated 02 Sep 2010 22:20 UT | No proton event in progress
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Current proton fluxes are as follows:
Last updated 02 Sep 2010 22:20 UT
| GOES Gp satellite Energetic Proton Flux (Courtesy of SWPC, Boulder Colorado, USA)
Units: Protons/cm2-s-sr
10MeV and 100MeV threshold proton flux level is 10 proton flux units (PFU)
Date: 02 09 2010 2210 UT
1MeV Proton flux: 1.09e+00
5MeV Proton flux: 1.68e-01
10MeV Proton flux: 1.34e-01
100MeV Proton flux: 2.83e-02
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Proton flux data for this page are provided by the US Space Environment Service (SEC).
For more details see Today's Space Weather from Space Weather Prediction Center in Boulder.
HF Systems