Yep Gavin, a big number weather stations up and down eastern Australia have recorded pronounced oscillations in pressure as the gravity waves arrived (I haven’t had time to check any further west though).
Here’s just a few of the ones I saved (a huge number of PWS’s recorded them as well), and a satellite loop:
https://live.staticflickr.com/65535/51820475272_8d62448af9_o.gif

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Hi all,See Ken's post on the Report I posted.I was correct. Certainly the best example I have ever seen. The famous Krakatoa between Java and Samartra ( Indonesia ) caused a similar effect around the world in August 1883 when it staged its huge eruption. It will be interesting to see the impacts ., particularly if the Volcano puts a huge amount of Sulphur Dioxide into the upper atmosphere as being located in the tropics it can have quite a marked impact on global temperatures as Pinatubo did in 1991/92 and unusual; fiery sun rises/sets. too. again Pinatubo (Philippines) /Cerro Hudson ( Chile) did .CheersGavin----- Forwarded message ---------
From: Ken Kato <kka...@hotmail.com>
Date: Sun, Jan 16, 2022 at 1:02 AM
Subject: RE: [austpacwx] Unusual Barograph recording noted this evening;Could it be a gravity wave from the eruption at Hunga Tonga-Hunga Ha'apai Volcano near Tonga?
To: aust...@googlegroups.com <aust...@googlegroups.com>
Yep Gavin, a big number weather stations up and down eastern Australia have recorded pronounced oscillations in pressure as the gravity waves arrived (I haven’t had time to check any further west though).
Here’s just a few of the ones I saved (a huge number of PWS’s recorded them as well), and a satellite loop:
https://live.staticflickr.com/65535/51820475272_8d62448af9_o.gif
Hi from Australia,
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From: Gavin O'Brien
Sent: Saturday, 15 January 2022 11:36 PM
To: aust...@googlegroups.com; Jeff and Marcia Kingwell; John O'Brien; Chris Rule; Don White; Michael O'Brien; Rachel Riches; Thomas Riches; Vivienne.Micheline.Thurgar; Shaun Cuskelly; Marjie Aguilana; Tim Morrow
Subject: [austpacwx] Unusual Barograph recording noted this evening;Could it be a gravity wave from the eruption at Hunga Tonga-Hunga Ha'apai Volcano near Tonga?
Hi everyone,
You will have seen on the TV news, video of the Tsunami impacting the Tonga Islands from the eruption on Hunga -Tonga-Hunga Ha'apai Volcano in the Tongan Island group located well out in the South Pacific northeast of the Queensland coast .The eruption occurred at 3.10 pm Eastern Australian Summer Time this afternoon, sending ash up to 10 kilometers altitude and generating Tsunamis onto surrounding island shorelines . For the first time in ages, the Australian East Coast has a Tsunami Watch current, as does most South Pacific Islands including the northern coasts of New Zealand .
I happened to look at my trusty Aneroid Barograph about half an hour ago and I was startled to see the sudden pronounced 'blip' in the trace around 1500 to 1600
hours, Eastern Australian Summer Time .Note the Barograph Clock time is slow as the real time was from 1945 hours , not 1415 hours (EST) .
Thinking to double check, I have downloaded the Barograph Data from the Davis Vantage Pro 2 PWS and plotted the Barometer Reading data with a second Chart showing the 5 minute variation in pressure variation. The PWS Data Logger is set to 5 minute intervals.
The weather here from this afternoon was quite settled, a few scattered small to medium Cumulus and some Cirrostratus at upper levels. Nearest storms were in the Goulburn area .
Please find attached the two sets of data and graphs. Any suggestions?
Cheers,
Gavin
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I actually did a rough calculation of this yesterday as follows:
Given the big eruption occurred at about 2pm, the first spike in pressure at Brisbane was at about 5pm, and the great circle distance between the eruption and Brisbane is ~3266km, that equates to an average speed of the gravity waves of 1088km/hr (still under the speed of sound which is ~1225km/hr at sea level at a standard 15C temp).
That 1088km/hr is an average as well as an estimate though. For example, it's quite possible that it was faster (as a true shockwave) much closer to the eruption when it first fired up.
Ken.
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I don’t know too much about it but I think it was due to the eruption itself (including the magma surging up through the water) which was near the side of the caldera and the cone formed in 2014/2015. It looked too close to the water level to form a big pyroclastic flow. But I stand to be corrected.
Incidentally, here are some gifs which illustrate the sheer power of it. And also the volcanic ash which reached QLD this morning:
https://twitter.com/burgwx/status/1482732634077732868
https://twitter.com/wni_jp/status/1482350492282134530
These pressure oscillations were also recorded as far away as Europe.
Photo from Kyra Fleet:

Photo from Dave Brown in Kawana Waters:

Suzette Reid from Kurrimine Beach:


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