March 2, 2010 Geomagnetic Disturbances

by Jim Kearman, KR1S

Updated March 3, 2010 reported a Coronal Mass Ejection (CME) event occurring on March 1. According to the site, "The eruption hurled a billion-ton CME away from the sun, but not toward Earth." Perhaps, but some of it hit Earth, as these images captured at about 1700 UTC on March 2 indicate.

Northern Hemisphere Aurora

This image is from the NOAA POES satellite. A red auroral oval doesn't necessarily mean terrible MW propagation, but signals traveling near or through the oval -- especially on E-W paths -- are usually attenuated. You can see the current northern oval at NOAA's POES Website.

Canada has established several geomagnetic-field monitoring stations in the high Arctic. Their measurements are more informative and useful than the mid-latitude summaries provided by the US NIST or WWV. The charts are displayed in decreasing latitudes. Yellow bars are not so good; orange bars usually mean the geogmagnetic field will be disturbed for a few days. You can see the current plots at Natural Resources Canada's Website.

High Latitude Geomagnetic Field

What's this mean for MW DXing? Signals that must cross geomagnetic lines will be attenuated, whereas signals traveling parallel to magnetic lines will be less attenuated. Signals traveling through or near the polar regions will be greatly attenuated. If you live near the extended auroral oval you might find it harder to hear signals outside the oval. If you live outside the oval, signals to the south (for Northern Hemisphere DXers) may be weaker, but the disturbance can be an advantage. Signals to your north will be weaker, as will signals to your east and west. Signals to your south that you can't normally hear because of interference may now be audible.

Conditions will remain like this for 3-4 days, then slowly improve. Solar events often repeat once or twice at 28-day intervals, so expect disturbed conditions again at the end of the month.

Links to the NOAA and NRC sites, as well as other propagation-information sites are available on the KR1S Home Page.

March 3, 2010

Some observations on pre-dawn propagation to South Florida this morning. Several stations that are normally very strong here showed effects of some propagation disturbance. I recorded a series of 10-second clips made between about 1000Z-1100Z (0500 EST-0600 EST). Sunrise here today was at 1143Z (0643 EST). For each recording I peaked the antenna on the station in question. Each file is only 80 kB so they should play on any connection. In order of recording:

WSM 650 kHz, Nashville, 1005Z. Normally dominates this frequency. Note rapid flutter.

TWR Bonaire 800 kHz, 1007Z (40 minutes before their sunrise). Also usually strong at this hour.

This should be WWL 870 kHz, New Orleans, as R Reloj is in the antenna null. Where's WWL?! And note rapid flutter on R Reloj, well before sunrise there. (1011Z)

WSB 750 kHz, Atlanta, 1015Z. Another dominant pest. In the background is either Cuba or Venezuela, both of which are normally very hard to hear under WSB.

WBT 1110 kHz, Charlotte, NC, 1017Z. Yet another dominant pest. Clearly heard under WBT is CMKO (R Angulo) in Holguin Province, Cuba.

WCKY 1530, Cincinnati, 1054Z. Cincinnati sunrise was 1208Z, and this station is also normally dominant. The only other station I've ever logged on 1530 is WYMM in Jacksonville, Fl. Note the very rapid flutter, which sounds auroral.

This should be WBBR 1130, New York City, with KWKH Shreveport underneath, as the antenna is favoring NYC/Boston. I believe the dominant station in this clip is CMKA, also in Holguin Province, Cuba. KWKH, like WWL in New Orleans, is to my west, and was inaudible even when the antenna favored that direction. (1102Z -- NYC sunrise 1127Z. WBBR is usually still strong 30 minutes after their sunrise.)

KMOX 1120, St. Louis, 1105Z. Normally much stronger. Again, note rapid flutter.