HAMNET Report 27th May 2018

HAMNET is very encouraged by the news in this morning’s SARL bulletin that a 100kHz portion of the 5Mhz band will be opened on a shared basis to radio amateurs. For a long time, emergency communicators have needed a gap-filler between 80 metres and 40 metres, to transmit messages when conditions are poor, and now we have one. Once the band-plan has been published, HAMNET Directors must get together and specify an emergency frequency for future use. However, we must note the restriction of 15 watts e.i.r.p. on our signals, because the band is shared.

From the NASA Disaster Response blog, comes news of the work done by them to catalogue what is happening in Hawai, as the volcano continues to erupt.

NASA is tracking lava flows from Hawaii Island’s Kilauea volcano as fissures erupt and lava makes its way to the ocean.

Using data from the Visible Infrared Imaging Radiometer, or VIIRS instrument, aboard the NASA-NOAA Suomi NPP satellite, NASA’s Disaster Program has been tracking thermal anomalies, or hot spots, indicative of lava flow. VIIRS is the only instrument from space that can track lava flows through hot spots, making it an important additional source of information for the U.S. Geological Survey as it monitors and informs the public of the ongoing volcanic activity, which has produced everything from earthquakes and giant rock projectiles from eruptions, to blankets of ash clouds and volcanic smog, or vog.

In addition to VIIRS, NASA provides other information on volcanic activity, including aerosol and sulphur dioxide measurements derived from the Ozone Monitoring Instrument (OMI) aboard NASA’s Aura satellite as well as the Ozone Mapping Profiler Suite aboard NASA-NOAA Suomi NPP satellite, and ground deformation and movement with synthetic aperture radar data.

NASA also organized a field mission with airborne radar to provide accurate digital elevation maps that USGS can use to predict lava path flows. Flown on the G-III research aircraft, the Jet Propulsion Laboratory’s Glacier and Ice Surface Topography Interferometer (GLISTIN) instrument is detecting changes in Kilauea’s topography associated with the new lava flows, with the goal of measuring the erupted volume as a function of time and ultimately the total volume of the event.

I doubt whether any other volcano has had the benefit of observations from space like this one. And the volcano hasn’t settled down yet.

It would seem that the Dayton Hamvention was a resounding success. Writing in the Xenia Daily Gazette, Anna Bolton noted that Michael Kalter, official spokesperson for Dayton Hamvention, said he thinks the numbers were higher than last year’s 29,296. Kalter said the weekend went smoothly, thanks in part due to the effectiveness of the county, city, township, fair board and all parties working together.

Kathleen Wright, executive director of Greene County Convention & Visitors Bureau, agreed that the travellers seemed to enjoy their time in Greene County.

“So many are already beginning the countdown for next year’s event. I simply cannot say enough nice things about the people from all over the world who participate in this world class event. With over 600 volunteers led by Dayton Amateur Radio Association members, this event proves to be highly organized. We look forward to hosting this event for many years to come,” she said.

It is a pity that events like this are so inaccessible to us, isn’t it? New equipment, masses of accessories, and lots of lectures inside the venue, as well as an enormous fleamarket outside to curb everybody’s appetite. Sounds too good to be true!

On the 17th of May, the ARRL News reported on findings during the Solar Eclipse QSO Party last year in August.

The first science results from the Solar Eclipse QSO Party last August 21 have been published in the American Geophysical Union journal Geophysical Research Letters. In the paper, “Modelling Amateur Radio Soundings of the Ionospheric Response to the 2017 Great American Eclipse,” Nathaniel Frissell, W2NAF, and team, present Reverse Beacon Network (RBN) observations of the SEQP and compare them with ray tracings through an eclipsed version of the physics-based ionospheric model SAMI3. Frissell, a New Jersey Institute of Technology (NJIT) research professor, explains that ray tracing is a method of calculating where a radio wave will go based on electron density — essentially the same as calculating how a light ray passes through a lens. HamSCI, the Ham Radio Science Citizen Investigation organization, sponsored the event.

“From a ham radio perspective, this paper very clearly shows the effect of the eclipse on not just a few, but a very large number of contacts,” Frissell told ARRL. “You can see from the charts that activity drops off steeply on 20 meters during eclipse totality, while 80 and 160 meters open up. On 40 meters, you can see how the contact distance increases in step with the eclipse.”

Frissell said another key aspect of the paper is that the researchers were able to use ray tracing to compare the observations to a physics-based numerical model of the eclipsed ionosphere. “We did this by ray tracing hundreds of thousands of ray paths on the NJIT supercomputer,” Frissell explained. “The development of this method of comparison also gives us a new tool for comparing datasets like the RBN, to actual models.”

On 14 MHz (20 metres), eclipse effects were observed as a drop off in communications for an hour before and an hour after eclipse maximum. On 7 MHz (40 metres), typical path lengths extended from about 500 km to 1,000 km for 45 minutes before and after eclipse maximum. On 1.8 MHz (160 metres) and 3.5 MHz (80 metres), eclipse effects were observed as band openings 20 to 45 minutes around eclipse maximum.

By using ray tracing to compare these observations with the SAMI3 model, it was found that the majority of 14 MHz signals refracted off the ionosphere at heights less than 125 km in the E region. On the lower bands, 1.8, 3.5, and 7 MHz, it was found that signals likely refracted off heights greater than 125 km in the F region.

These observations suggest an eclipse-induced weakening of the ionosphere, and are consistent with numerous prior HF radio eclipse ionospheric studies. Congratulations to Nathaniel and his team on this ground-breaking research.

This is Dave Reece ZS1DFR reporting for HAMNET in South Africa.