The Io B Storm of  Nov 27 2001

At least from Hawaii, the current Jupiter observing season had been a bit disappointing up until this Io B session.  This was to be one of the most exciting Jupiter sessions I had ever experienced. Some of the excitement was from Jupiter, some from much closer.

A tremendous rain front had moved over the Hawaiian Islands on the previous day. The downpour was continuous and hard.  I live in an Ohia forest on the Big Island of Hawaii.  Around my house are many Ohia trees which stand over 100 feet (33m) in height. Many trees had been damaged by the unusually dry conditions experienced on this part of the Island over the lhast several years.  These trees stand in just a few inches of soil, beneath which lies an impenetrable layer of lava.  All of these conditions combined, led to a large number of these giants toppling to the ground during the rain storm.  On the day prior to the Jupiter session, I watched helplessly as an 80 foot tree fell on a dipole antenna that I had placed in the woods near the house. This was the setting in which I would observe Jupiter; rain roaring on the tin roof of my observatory and the occasional crash of a large limb or tree as it fell in the dark nearby.  Fortunately, lightning was not a concern. Lightning is a very rare occurrence here, so even though there was much rain there was no lightning danger to the antenna, or interference from nearby lightning to the observation.

Our power had been out for part of the day when a limb took out the high voltage line in my area. Luckily, a utility crew repaired this in just a few hours, however, we were not so lucky as far as the Windward Community College Radio Observatory on the Island of Oahu was concerned. The power there failed repeatedly and it was impossible to keep the observatory functioning.  This is a shame, for no doubt, the WCCRO is much better equipped and would have produced some fine records of the Jupiter storm.


My main antenna is a  "wire and stick"  log periodic antenna which I hang via a rope from one of those tall unstable Ohia trees. I can aim the antenna about 30 degrees either side of the zenith by raising the bottom of the antenna or propping up the bottom and lowering the top.  The log period does not provide much gain but it does provide fairly good coverage from 18 to 30 MHz. The line from the antenna passes though a 18 to 30 Mhz band pass filter, a 12 dB MMIC preamp, and finally a splitter so that more than one radio can be fed from the same antenna. An RF Associates calibrator can also be switched into the line.

"Wire and stick" log periodic antenna suspended from a tall Ohia tree.

The receivers were a Radio-Shack DX-392 on 20.09 Mhz and a Kenwood TS530s on 18.3 MHz.  Product detection was used in both receivers and AGC was defeated to best of my ability.  

Radio-SkyPipe was used on a 577 Mhz PC to collect and stream data. Wav files were recorded on the same PC using the Radio-SkyPipe WAV Recorder (Pro Edition only). I do not have broadband access here in my rather remote location. A single Dial-Up connection to the internet is used by all of the PCs in my home via an Ethernet network and Microsoft Internet Connection Sharing software on the PC in my office.  Even though I had four or five users connected to my Radio-SkyPipe server, there was plenty of bandwidth to work with.


Attended observations began 14:00 UT (4:00 AM HST) and continued until a power outage at 16:50 UT brought things to a halt.  Luckily, I was able to retrieve data files from two people who were observing my server stream via Radio-SkyPipe.  Radio-SkyPipe has a feature which allows real-time backups, but I had neglected to turn the feature on in this installation!

Conditions were excellent, at least as far as interference and ionospheric transparity was concerned.  

There was sporadic activity throughout the observed period, beginning with S-Bursts and during the peak of the storm primarily turning to L-Bursts activity.  This was followed by a period where L and S-Bursts began to merge into some intermediate form. Three charts are shown below with sound clips in wav format. I recorded the sound files at much too low a level and so lost much of the dynamic range that evident at the sound was heard on the computer speakers. These sound files were amplified using Goldwave software in a post collection process. The 18 MHz channel is particularly weak, but is preserved in all but the first sound file (the S-Burst File)


S-Bursts as recorded by Radio-SkyPipe. The upper trace (blue) is 18.3 MHz. The lower trace (red) is 20.09 MHz. 

Corresponding S-Burst Sound File.


The chart above shows the moderate level L Bursts. Bursts levels were about 6 dB above the galactic background.

Corresponding L-Burst Sound File.


Sometimes, it becomes hard to say whether or not a particular Jupiter bursts is of the S or L type. Perhaps these are just S-bursts superimposed upon L-Bursts or perhaps some intermediate mechanism is at work. There is much to learn about Jupiter. The above chart represents this type of activity.

Corresponding S and L-Burst Sound File.

Ocean Waves

The sound file below is from this same Io-B storm. It is included because I thought it was a particularly good example of the rapid ocean wave L-Burst sound that is often referred to in the literature. Listen closely to the second array of bursts at the end of the recording to hear this effect.

Ocean Wave L-Burst Sound File.