June 1996 Solar-Minimum VLF Expedition to Alberta, Tracks 1 - 5

1) Beautiful sounding wavering tones and risers mimicking whale song and tropical birds. I consider this one of my finest recordings ever made of a truly gorgeous mixture of VLF phenomena. This track was recorded 02 June 1996, in the Whitemud River area, northwestern Alberta, at 4:15 a.m. MDT (1015 UT). This particular trip to northern Alberta and the Northwest Territories was undertaken during the solar-minimum period when sunspots and associated magnetic-field disturbances are at a minimum. I was intensely curious as to what VLF phenomena could be recorded in the auroral-zone region, and secondly, I really wanted to experience some bright midnight twilight in the Far North. The morning of June 2nd and following day turned out to be the most spectacular day of the entire 15 day trip to and from Marin County, California . A beautiful red sunrise was about to happen shortly after this recording was made. McGreevy WR-4 receiver with 10-ft. vertical antenna . Duration 11:12

2) Nose whistlers mixed in with slowly rising and falling emissions occurring in ping-pong fashion taped almost 4 hours after track 1 above. There is also weak medium-pitched hissband in the background and an overall low level of lightning static (lightning would move into the local area later in the day threatening me with nearby ground strikes!...) At 4 minutes, 37 seconds into this track there is a weak lightning static burst, followed about three seconds later by one of the loudest nose-whistlers recorded on this track and during in this time period of the morning. An echo of this nose-whistler also follows from three to five seconds after. Why are they called "nose-whistlers?" Nose whistlers, heard mainly at higher geo-magnetic latitudes such as in central and northern Canada, contain both rising and falling components occurring simultaneously, and spectrograms of them look like an image of a person's nose. Recorded on 02 June 1996 at 8:00 a.m. MDT (1400 UT): Duration 5:49 Spectrogram of a Nose Whistler - S.P. McGreevy (nosewhi.jpg) 3-5) Lightning is moving into the area and building up intensity! It is by now generating some quite spectacular sounding nose whistlers preceded by strong lightning static. Note that the lightning static is most strongest in track 5 when lightning was within 10 km of my monitoring and recording location. These three tracks were recorded on 02 June 1996 between about 11:45 and 13:00 Mountain time (1745 - 1900 UT) Track Durations: Track 3 is 1:30, Track 4 is brief, only 20 seconds, Track 5 is 4:02.

Four Tracks of recordings made during my Summer '96 Solar-Minimum VLF Expedition to Manitoba, Canada (Grass River Provincial Park), 22 August to 05 September 1996, Tracks 6 - 9

These two weeks right in the auroral-zone were awesome! When I arrived on 22 August 1996 to this central Manitoba location deep within the Canadian boreal forest, there was a moderate magnetic-storm in progress and the Aurora Borealis (Northern Lights) appeared over the entire sky the first and second nights of my stay. Despite declining magnetic disturbances until the 29th of August and a waxing moon - soon to be full on the night of the 28th, the aurora never failed to dazzle me with hours of truly beautiful sights in the nighttime skies, sometimes just a faint arch to the north but often breaking out into lovely forms: swirls, pillars, and so on. So determined was I to remain as long as I could that I ran low on food the last couple of days (September 3 - 5) and I had to resort to boiling and filtering pond water nearby, as my fresh water supply nearly ran out. But, those extra few days up there were truly worth it. The next five tracks are a few of my favorite segments, but only a tiny bit of the 20 hours of recordings made those two weeks.

6) Another Auroral-zone recording: A mixture of generally low and medium-pitched chorus of moderate intensity. Interesting sounding bursts of low squawks and then higher pitched chirps in response. Recorded 28 August 1996 at 8:50 a.m. Central Daylight Time (1350 UT). Duration 3:00

7) Low-pitched hissband of quite loud intensity (sounding like a jet plane in flight) and a couple of weak fast pure-tone whistlers toward the beginning of this track. There are also numerous risers (the opposite of whistlers). Recorded 24 August 1996 at 11:00 a.m. CDT (1600 UT) Duration 1:10

8) Very interesting low-pitched activity strictly limited to near and in-auroral zone locations. Extended-duration risers and low-pitched wavering tones and low-pitched hissband - all sounding like a Halloween/ghost sound-effect tape! Recorded 24 August 96 at 10:00 a.m. CDT (1500 UT) Duration 3:01

9) In this track, the chorus is higher-pitched. It is occurring in "trains" that intermingle in varying pitches that subtly rise in pitch over their few-second durations. Characteristic of early-morning/early-post-sunrise chorus in start-up phase. Very pretty, albeit a short track on this CD of duration 1:10. recorded 28 August 96 at 7:12 a.m. CDT (1211 UT).

Stereo Recording VLF Expedition to Waterton Peace Park, southern Alberta Canada, 20 June 1998, Tracks 10 - 18

Three night's stay in Belly River Campground resulted in some wonderful stereo recordings - the first ones on CD that I know of. I took my father on a retirement celebration trip to Glacier National Parks and Canada's Waterton Peace Park, and also prepared for the first time to record natural VLF radio phenomena in stereo using two large loops oriented cross-azimuth. These loop antennae, both about 400 feet of wire wound and bound together into a 6-turn configuration, where hung in a couple of Aspen trees in triangular form. The recording equipment and filter/amplifier portions of the two loop receivers were located in my van parked in Campsite #20, far from electric powerlines, the nearest being in Waterton Park Townsite 30 km to the north. Even so, weak hum from them was picked up in the loop antenna oriented north/south.

In Tracks 10 and 11, the RIGHT-channel loop was oriented to be most sensitive to VLF signals coming along the magnetic longitude (also has some powerline hum) and the LEFT channel loop oriented to null signals coming from the magnetic longitude (i.e. oriented 90 degrees in azimuth away from the left channel loop along an east/west orientation). The receiver connected to the east/west loop antenna was a bit more sensitive to the higher audio frequencies and less sensitive to the lower audio frequencies, and also, this receiver has a bit more internal noise. Alas, due to time constraints before the trip was undertaken, I was not able to build two identical VLF loop-receivers.

In Tracks 13 through 18, the opposite is true - the LEFT channel loop is most sensitive to the north/south magnetic longitude direction (due to a switch in recording equipment used to make this CD and I not getting the patch-cord connections the same as in tracks 11 and 12. In any case, the results were interesting: the ever present late spring lightning static, sometimes strong in intensity from afternoon thundershowers plaguing the region, are very noticeably directional - the snapping and crackling sounds of the static are clearly different in both channels, but not so obvious in direction are whistlers and the majority of the chorus components, though SOME directionality to the whistlers and chorus is obvious. This indicated to me that the whistler and most chorus signals were coming from the more vertical plane, whereby both loops, being that they were hung vertically in trees, were directional in the horizontal plane but not the vertical plane. As such, most of the whistlers and chorus were arriving along magnetic lines-of force from a more vertical direction- as it could be said - from above!

These are the first known stereo natural VLF radio recordings released on CD. Portions of these recordings were aired on National Public Radio in the U.S. and also the Canadian Broadcasting Corporation.

10) This track was the first stereo natural VLF radio recording of dawn chorus I uploaded to the Internet for all to hear - it is of very strong dawn chorus of moderate density. The chorus in the left channel is lower pitched that the right channel - directionality of chorus is quite noticeable in this track. Recorded 20 June 1998 at 8 a.m. MDT (1400 UT). Duration: 1:22

11) STEREO:This brief segment was the first stereo natural VLF radio recording of whistlers I put on the Internet in early 1999. It is of beautiful near-pure-tone whistlers streaming down at a high rate, recorded 19 June 1998 at about 8:00 p.m. MDT (20 June 98 - 0010 UT) Duration 0:34

12 and 13) STEREO: These two brief tracks are more stereo whistler recordings I had placed on the Internet - essentially the same activity as the track above. Track 12 duration is 0:19 and track 13 is 0:38 -

14) STEREO: A long, recording of whistlers taped around 7:45 p.m. 0145 UT. Note the triggered emissions (diffuse sounding risers that occasionally show up in the LEFT track from about 15 seconds into this track!) Also, many of the whistlers vary in their loudness either in the left channel or the right channel, and even though the whistler rate is a bit lower in this track 14 than in the two tracks above (12 and 13), there is other VLF phenomena activity to hear., making for an overall fascinating recording! In this long track, the LEFT channel (with more powerline hum) is the loop antenna facing north/south as described earlier. Duration 4:33

15) STEREO: Made using the identical receiver settings and loop connections as Track 14, this , long, lovely stereo recording of chorus was made about 13 hours later than Track 14's recording, at about 8:15 a.m. MDT (1415 UT), 20 June 1998. There is noticeable directional effects in the chorus elements, and at 2 minutes 55 seconds into this track, there is a lightning static burst generating a diffuse, hissy whistler 3 seconds later, most noticeable in the right channel. Duration: 5:03

16) STEREO: The chorus is much more dense in this track than the previous track (15). Recorded a bit later on in the morning, at about 9 a.m. MDT (1500 UT) 20 June 1998. Duration 2:33

17) STEREO: The chorus is past peak density and beginning to wane in density, but is quite loud anyway, and the individual components are more readily audible. Recorded about 9:30 a.m. MDT (1530 UT). Duration: 2:57

18) STEREO: This track contains two segments: The first is from 0 seconds to 45 seconds into the track, the second segment is from 46 seconds to the end. Both segments were taped during the waning phase of that morning's chorus event. Recorded 20 June 1998, approx. 9:00 a.m. to 9:15 a.m. MDT (1600 - 1615 UT). Duration: 2:43

Produced and mastered by Stephen P. McGreevy, Stereo Natural VLF Radio Phenomena Recordist, Autumn 1999