On March 17, 2015, which also happens to be St. Patrick's Day, the strongest geomagnetic storm of Solar Cycle 24 occurred following a coronal mass ejection (CME) impact. This page provides data and imagery regarding the event as it unfolded.

On March 15th, 2015, A sunspot numbered 2297 which had been responsible for a number of moderate M-Class solar flares and one X-Class event, produced a long duration C9 solar flare at 02:13 UTC. While a C-Flare might not typically grab much in the way of attention, the magnetic characteristics of the eruption caused a partial halo coronal mass ejection (CME) to be flung into space and appeared to have somewhat of an Earth directed component. A minor impact past our planet was predicted for late on Tuesday, March 17, 2015.

On March 16th, 2015, Energetic proton levels streaming past our planet were on a gradual rise, an early indication that an interplanetary shock wave was on course with our planet.

At 04:05 UTC on March 17th, 2015, an earlier than expected shock passage was detected by the ACE spacecraft. Solar wind speeds as measured by ACE increased to above 500 km/s, while the Bz component of the interplanetary magnetic field (IMF) was initially pointing north, a condition known to suppress geomagnetic activity.

Half an hour later at 04:35 UTC, a geomagnetic sudden impulse measuring 54nT was recorded by the USGS ground based magnetometer in Boulder, Colorado. This signaled the moment the interplanetary shock wave (coronal mass ejection) swept past our planet. Initially conditions did not look favorable, however the Bz/IMF component soon began to point sharply south for long periods (-23nT peak). This allowed an energetic solar wind to interact with our geomagnetic field, thus leading to what I am calling the St. Patrick's Day Storm of 2015. Over 24 hours of storming, a majority of which was above moderate levels, led to incredible aurora displays at middle to high latitudes. Ham Radio Operators located across northern tier sections of Europe and North America utilized geomagnetic activity enhancements which is known to reflect signals in the very high frequency (VHF) radio spectrum. Because of the long duration of the event, sky watchers from Europe, Canada, northern tier sections of the USA, New Zealand and even Australia were able to witness some of the best aurora displays in years.

Below is detailed imagery data regarding the event.

C9 Solar Flare Observed @ 02:13 UTC (March 15).
Image by SDO @ 094 angstroms channel.

Halo Coronal Mass Ejection Observed.
Image by LASCO C2.

Low Energy Proton Enhancement following flare.
Data by GOES-15.

Energatic Protons on the rise in advance of impact.
Data by ACE.

Incoming CME initially detected by ACE
@ 04:05 UTC (March 17).

Geomagnetic Sudden Impulse detected
@ 04:35 UTC (March 17).

Active Aurora Oval following impact.
Data by OVATION.

GOES Magnetometer Data During Storm

Kp Index (KP=8) G4 Storm

Wing Kp Data during storm.

ACE 3-Day Data.
Captures periods of southward Bz following impact.

Aurora Photography Captured During the Storm.

By Zoltan Kenwell
Alberta, Canada

By Zoltan Kenwell
Alberta, Canada

By Brian Drourr
Vermont, USA

By Marketa Murray

By Andrew Lunt
Alberta, Canada

By Gilles Boutin
Quebec, Canada

By Monika Deviat
Alberta, Canada

By Dominic Cantin
Quebec, Canada

By Ruth Berggren

By Henry Jun Wah Lee

By Paul Zizka
British Columbia, Canada

By Carl Johnson

By Robert Kucirek

By Sylvain Wallart

By Mike Isaak
Alberta, Canada

By Daniel Thomas
Quebec, Canada

By Julian Filipowicz

By Jonny Cooper
Lapland, Sweden

By Paul Brooks
Iowa, USA

By Jake Stehli
Wisconsin, USA

By Jasper Meddock
Wisconsin, USA

By Mike Taylor
Maine, USA

By Jay Reau

By Ron Prchal
Minnesota, USA

By Linda Richmond
Melbourne, Australia

By Tony Travaglia
New Zealand

By Marketa Murray

By Eduardo Feldman
Yukon, Canada

By Vaughn Johnson

By Joe Lagos
Alberta, Canada

By Chris Ratzlaff
Alberta, Canada

By Theresa Tanner
Alberta, Canada

By Leonard Bevaart
Alberta, Canada

By Kirsten Buckle

By Ron Horn

By Zoltan Kenwell
Alberta, Canada

Thanks for reading and I hope you enjoyed this presentation regarding the St. Patrick's Day 2015 Geomagnetic Storm.