HAMNET Report 1st November 2020

There has been a string of Typhoons in the area of the Philippines and bearing down on the East coast of Vietnam. Last weekend, news started to arrive of Typhoon Molave approaching Vietnam, with the potential to cross into Laos and Cambodia. A day or two later, Typhoon Goni, with maximum expected wind-speeds of 278 km/h, whipped across the Northern tip of the Philippines and headed off towards Vietnam as well. And on Friday, Dani, YB2TJV, reported that the Philippines EmComm organization was standing by for Typhoon Rolly, with expected wind-speeds of 200 km/h. Their EmComm coordinator, Mr Jojo DU1VHY is requesting all operators to avoid 7.095 MHz and 7.110 MHz, the IARU Region 3 EmComm frequencies.

On the other side of the globe, Hurricane Zeta has spent time in the Bay of Mexico this week, potentially coming ashore on the coastline of Louisiana, expected to affect about 850000 people living there with wind-speeds up to 176 km/h. The
ARRL reported that WX4NHC at the National Hurricane Centre in Miami was activated at Midnight UTC on Tuesday to monitor 14.325 and 7.268 MHz as well as the VoIP Hurricane net and other resources from there on.

Not to be outdone by violent windstorms, Turkey and Greece were struck by a magnitude 7 earthquake at a depth of 10km, just offshore in the Mediterranean at about midday UTC on Friday. Sotirios, the Amateur Radio Head of Greece’s EmComm Agency, reported to Greg, G0DUB, that there were some injured people being transported to Samos Hospital, and there were damaged houses in the Karlovassi area. Sotirios said his operators were online with Greek Civil Protection, and also had ham operators in their Operation Centre.

Greg G0DUB has also announced that IARU Region Two (the Americas) has appointed a new Emergency Communications Coordinator in the person of Dr Carlos A Santamaria CO2JC. He succeeds Dr Cesar Pio Santos HR2P, who recently retired after 12 years of service.

Dr Santamaria has extensive experience serving as Federacion de Radioaficionados de Cuba coordinator of the National Emergency Network (REN) both in exercises and communications during activations in the event of hurricanes and even earthquakes, maintaining contact with the coordinators of other Caribbean countries to protect emergency frequencies.  He also advises the Cuban headquarters of the United Nations Organization on Emergency communications during disasters, so is an ideal candidate for the post. I am sure we join all countries in wishing Dr Santamaria well in his new post.

HAMNET in the Western Cape will be assisting next Sunday the 8th of November in the running of the Jonkershoek Mountain Challenge cross-country race. Eight operators have been asked for, and Michael, ZS1MJT, our Regional Director tells me all posts have been filled. I hope to have a report of the race in the bulletin two weeks from now.

It seems strange to be discussing these effects only in 2020, but Brett Carter, writing in MENAFN on 27th October, talks about the effects of atomic bomb tests on our upper atmosphere, and the potential to damage the ionosphere. He says:

“Indeed, surface and atmospheric (high-altitude) detonations of nuclear weapons can have short-term and long-term effects.

“One short-term effect was a temporary blackout of long-distance high-frequency (HF) radio communication over the surrounding area. But this radio communication blackout was not a result of the nuclear explosions destroying the ionosphere.

“On the contrary, the nuclear detonations temporarily increased the natural level of ionisation in the upper atmosphere.

“In long-distance HF radio communications, the radio waves are bounced back and forth between the ionosphere and the Earth’s surface. This means you don’t need to establish a line of sight for HF radio communication.

“Many applications, such as emergency services and aircraft/maritime surveillance, rely on this mode of HF radio propagation.

“But this radio communication scheme only works well when there is a reflective E or F layer, and when the absorbing D layer is not dominant.

“During regular daytime hours, the D layer often becomes a nuisance because it weakens radio wave intensity in the lower HF spectrum. However, by changing to higher frequencies you can regain broken communication links.

“The D layer may become even more dominant when intense X-ray emissions from solar flares or energetic particles are impacting the atmosphere. The absorbing D layer then breaks any HF communication links that traverse it.

“Nuclear detonations also produce X-ray radiation, which leads to additional ionisation in all layers of the ionosphere. This makes the F layer more reflective to HF radio waves, but, alas, the D layer also becomes more absorptive.

“This makes it difficult to bounce radio waves off the ionosphere for long-distance communication soon after a nuclear explosion, even though the ionosphere stays intact.

“Beyond additional ionisation, shock waves from nuclear detonations produce waves and ripples in the upper atmosphere called ‘atmospheric gravity waves’ (AGWs).

“These waves travel in all directions, even reaching the ionosphere where they cause what are known as ‘travelling ionospheric disturbances’ (TIDs), which can be observed for thousands of kilometres.

“Bomb blasts are not the only things that cause disturbances in the atmosphere.

“In September 1979, there were reports of bright flashes of light off the South African coast, igniting theories South Africa had nuclear weapon capabilities.

“Analysis of ionospheric data from the Arecibo Observatory, in Puerto Rico, confirmed the presence of waves in the ionosphere that corroborated the theory of an atmospheric detonation. But whether the detonation was artificial or natural could not be determined.

“The reason for the ambiguity is that meteor explosions and nuclear detonations in the atmosphere both generate AGWs with similar characteristics.

“The 2013 Chelyabinsk meteor explosion in Russia generated waves in the ionosphere that were detected all across Europe, and as far away as the United Kingdom.

“Volcanic eruptions, such at the 1980 Mount St Helens eruption in the US, and large earthquakes, such as the 2011 Tohoku earthquake in Japan, are other examples of energetic processes at the ground impacting the upper atmosphere.

“Another well-known source of ionospheric disturbances is a geomagnetic storm, typically caused by coronal mass ejections from the Sun or solar wind disturbances impacting Earth’s magnetosphere.

“In summary, nuclear detonations can impact the upper atmosphere in many ways, as do many other non-nuclear terrestrial and solar events that carry enormous energy. Fortunately, the interference isn’t permanent.”

Well, after all these years, this news is certainly reassuring!

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