HAMNET Report 14th May 2023

Tropical Cyclone Mocha-23 has arisen in the Bay of Bengal, and has been monitored since this Thursday. It originally travelled due North in the direction of Bangladesh, but by Friday was swinging north-east, aimed at the coast of Myanmar, and the Eastern-most edge of Bangladesh, due to cross the coast at about midday their time today (Sunday).

Maximum wind-speeds of 170km/h are currently forecast, and the cyclone will have a high humanitarian impact as it hits a densely populated area, with 3 million people directly in its expected path. From 12-14th May, heavy rainfall, strong winds and storm surges are forecast for western and south-western Myanmar. The Alert Level is already set at RED.

This weekend sees the first of South Africa’s real winter cold fronts crossing the country. A prominent bank of cloud was visible on the Eumetsat weather picture on Wednesday, which the concurrent synoptic chart showed was stretching all the way from the West coast of the Cape, right down through Marion Island and virtually to Antarctica.

The Western Cape had good rain on Friday, but the huge high pressure cell behind the front pushed our barometric pressure up from 1010 millibars on Wednesday evening, to 1027 millibars by Friday night.

As a result the Southern Cape coastal areas have suffered a strong south-easterly wind, bringing icy polar air up from Antarctica, and resulting in a snow forecast, stretching from the Matroosberg here in the Cape, along the mountains through the Eastern Cape, to the Drakensberg in KZN. Up to 10cm of snow has been forecast here and there, and I’m sure the Southern half of the country has felt the cold.

So stay indoors, and protect your animals and yourselves from exposure hazards.

From the New Zealand Herald’s website comes a thoughtful dissertation on how to avoid “Disaster Fatigue”.

Massey University emergency management lecturer Dr Lauren Vinnell described disaster fatigue as a “specific type of exhaustion” when events of the same nature repeated or multiple different events happened all at the same time.

“It’s a general term. It’s not a specific disorder that you might get diagnosed with so it can look different for different people in a different context.”

Symptoms include tiredness, lack of sleep, difficulty making decisions and unusually strong emotions.

Vinnell, of the Joint Centre for Disaster Research, said these impacts were not uncommon following an event like this week’s major flooding in New Zealand.

It is when these symptoms persist and have a negative impact on people day-to-day that it becomes a problem.

Vinnell said it was important [that] people kept track of how they’re feeling and “if it’s not getting any easier over time” to start seeking help by talking to friends and family or [gaining] professional help.

“There are things that people can do just generally to help themselves feel better when they’re moving on from these sorts of events.

“Things like practising self-care, which I know is a bit of a buzzword that basically just means [that], if you can find time to do things that make you happy and refresh you, do so, whatever they may look like.

“It’s really important that people don’t overload themselves with negative information. You need to know enough to know what’s going on but spending too much time scrolling social media or whatever can be harmful.”

It was worth thinking about what steps people could take so that if it happened again they were more prepared to deal psychologically “with these quite daunting problems”.

Vinnell said people should prioritise making a plan with their family or household so everyone knows what to do during a traumatic event.

Thank you to the website nzherald.co.nz and Dr Vinnell for this summary.

In our country we don’t have that many natural disasters, but there are countless mini-disasters happening, like bus or taxi accidents, gender-based violence, mass shootings, or even informal settlement fires, all of which can increase the post-traumatic stress. And as the article says, it’s often the consecutive nature of the disasters, big or small, that lead to the fatigue.

One can easily see, for example, how countless sessions of load-shedding in any given week can add up, to cause complaints of tiredness, lack of sleep, difficulty making decisions, and unusually strong emotions.

So heed Dr Vinnell’s advice and so something that makes you feel happy, and refreshes you, like playing radio, and serving your community under HAMNET’s banner!

Writing in last month’s QST, Terry White, VE5TLW, says that a new antenna technology for VHF/UHF, developed by Upside Down Antenna Company promises to provide a breakthrough in RF communications. It effectively doubles the capacity of any VHF or UHF repeater.

The UpSide Down Antenna (USDA) replaces the existing antenna at a repeater site. It utilizes a special network (and there is a visual representation in QST) that combines the upright and inverted RF signal arriving at the repeater, and uses the existing transmission line. The USDA only responds to an upright or inverted signal and rejects the opposite signal. The manufacturer states that the isolation or rejection between the two signals is in excess of 60 dB.

To use the USDA system, you only need to hold your handheld radio in an upright or inverted position. Put out your call for your intended recipient in the upright position, and if there is no response, invert the radio and try again. While allowing for a bit of circular rotation of your signal, you must nevertheless hold the radio within an arc of 45 degrees of the upright or inverted position.

Two simultaneous conversations can then be held on the same repeater. So far the technology only works with handhelds, since the whole radio can be inverted. A USDA for mobile or base radio applications is in the pipeline.

Thank you to the much respected ARRL journal QST for these excerpts from their article.

Terry White doesn’t actually say as much, but I think the world famous Swedish Electronics Engineer, Prof Loof Lirpa, was involved in the development of the technology.

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