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HomeHF SystemsGlobal HFPolar Cap Absorption Sunday, Sep 25 2022 23:37 UT
Global HF

Polar Cap Absorption

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.

See 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 25 Sep 2022 23:30 UT)

10MeV (S1) Proton/PCA Event Began 28 10 2021 1730UT and is in progress 10MeV (S1) Proton/PCA Event Ended 30 10 2021 1335UT 10MeV Maximum proton flux of 2.90E+01 PFU (S1) observed at 29 10 2021 0250UT 10MeV (S1) Proton/PCA Event Began 30 10 2021 1435UT and is in progress 10MeV (S1) Proton/PCA Event Ended 30 10 2021 1505UT 10MeV Maximum proton flux of 1.05E+01 PFU (S1) observed at 30 10 2021 1435UT 10MeV (S1) Proton/PCA Event Began 30 10 2021 2050UT and is in progress 10MeV (S1) Proton/PCA Event Ended 30 10 2021 2120UT 10MeV Maximum proton flux of 1.12E+01 PFU (S1) observed at 30 10 2021 2105UT 10MeV (S1) Proton/PCA Event Began 20 01 2022 0755UT and is in progress 10MeV (S1) Proton/PCA Event Ended 20 01 2022 1515UT 10MeV Maximum proton flux of 2.27E+01 PFU (S1) observed at 20 01 2022 1015UT 10MeV (S1) Proton/PCA Event Began 28 03 2022 1315UT and is in progress 10MeV (S1) Proton/PCA Event Ended 28 03 2022 2030UT 10MeV Maximum proton flux of 1.87E+01 PFU (S1) observed at 28 03 2022 1450UT 10MeV (S1) Proton/PCA Event Began 02 04 2022 1425UT and is in progress 10MeV (S1) Proton/PCA Event Ended 02 04 2022 2235UT 10MeV Maximum proton flux of 3.22E+01 PFU (S1) observed at 02 04 2022 1600UT 10MeV (S1) Proton/PCA Event Began 27 08 2022 1150UT and is in progress 10MeV (S1) Proton/PCA Event Ended 27 08 2022 1830UT 10MeV Maximum proton flux of 2.75E+01 PFU (S1) observed at 27 08 2022 1220UT 10MeV (S1) Proton/PCA Event Began 27 08 2022 1915UT and is in progress 10MeV (S1) Proton/PCA Event Ended 27 08 2022 2125UT 10MeV Maximum proton flux of 1.44E+01 PFU (S1) observed at 27 08 2022 2045UT

/Images/HF%20Systems/Global%20HF/Polar%20Cap%20Absorption/ico_PolarCapAbsorption.gif

(last updated 25 Sep 2022 23:30 UT)

No proton event in progress

Note: Proton event descriptive text will lag realtime due to data smoothing.

Current proton fluxes are as follows:

(last updated 25 Sep 2022 23:30 UT)

GOES (Gp16) satellite energetic Proton Flux (Courtesy of SWPC, Boulder Colorado, USA) Data Date/Time: 25 09 2022 2320 UT Proton Energy Current Proton Level Flux Event Status 10MeV 6.12e-01PFU No proton event in progress 100MeV 2.76e-01PFU No proton event in progress 500MeV 2.69e-01PFU No proton event in progress Units: PFU = protons/cm2/sec/ster MeV = million electron volts Proton energy levels and PFU event thresholds: Proton Energy Proton Flux Level Threshold 10MeV 10PFU 100MeV 1PFU 500MeV 1PFU Gp: GOES primary Gs: GOES secondary Solar proton events can impact satellite operations and transpolar HF communications.

GOES satellite proton flux data for this page are provided by US Space Weather Prediction Center in Boulder.

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