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HomeHF SystemsGlobal HFPolar Cap Absorption Saturday, Dec 07 2019 08:49 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 07 Dec 2019 08:40 UT)

10MeV Proton/PCA Event Began 14 07 2017 0850UT and is in progress 10MeV Proton/PCA Event Ended 14 07 2017 1135UT 10MeV Proton/PCA Event Began 14 07 2017 1235UT and is in progress 10MeV Proton/PCA Event Ended 14 07 2017 1340UT 10MeV Proton/PCA Event Began 14 07 2017 1430UT and is in progress 10MeV Proton/PCA Event Ended 14 07 2017 1510UT 10MeV Proton/PCA Event Began 14 07 2017 1800UT and is in progress 10MeV Proton/PCA Event Ended 14 07 2017 1835UT 10MeV Proton/PCA Event Began 14 07 2017 1940UT and is in progress 10MeV Proton/PCA Event Ended 15 07 2017 1105UT 10MeV Proton/PCA Event Began 05 09 2017 0020UT and is in progress 10MeV Proton/PCA Event Ended 08 09 2017 1455UT 10MeV Proton/PCA Event Began 08 09 2017 1645UT and is in progress 10MeV Proton/PCA Event Ended 08 09 2017 2255UT 10MeV Proton/PCA Event Began 10 09 2017 1635UT and is in progress 10MeV Proton/PCA Event Ended 14 09 2017 1720UT

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

(last updated 07 Dec 2019 08:40 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 07 Dec 2019 08:40 UT)

GOES (Gp14) satellite energetic Proton Flux (Courtesy of SWPC, Boulder Colorado, USA) Data Date/Time: 07 12 2019 0830 UT Proton Energy Current Proton Level Flux Event Status 10MeV 4.12e-01PFU No proton event in progress 100MeV 6.06e-02PFU 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 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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