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#1439433 - 28/10/2017 10:21 Atmospheric Rivers
Flowin Offline
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I am not sure if this has been discussed before, but will ask anyway.
Has anybody heard of "atmospheric rivers" in the Australian context?
There is a body of science developing in the US about these, apparently channels of water vapour flow, and of interest to heavy rain events in California.
More info is here: https://www.esrl.noaa.gov/psd/atmrivers/
Noted in the US that they occur outside the tropics.
If it has been discussed before a link to post would help me.
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#1439434 - 28/10/2017 10:28 Re: Atmospheric Rivers [Re: Flowin]
Chris Stumer Offline
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It would be interesting to see if Australia gets them and what would happen if an atmospheric river did occur in South east Queensland.

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#1439435 - 28/10/2017 10:35 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Chris, I think SEQ is probably unlikely due to sub tropical climate and perhaps coast orientation. But perhaps somewhere like west coast Tas?
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#1439437 - 28/10/2017 10:42 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
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Originally Posted By: Flowin
I am not sure if this has been discussed before, but will ask anyway.
Has anybody heard of "atmospheric rivers" in the Australian context?
There is a body of science developing in the US about these, apparently channels of water vapour flow, and of interest to heavy rain events in California.
More info is here: https://www.esrl.noaa.gov/psd/atmrivers/
Noted in the US that they occur outside the tropics.
If it has been discussed before a link to post would help me.


Very interesting....you could argue NW Cloud bands are similar?

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#1439445 - 28/10/2017 12:11 Re: Atmospheric Rivers [Re: Flowin]
KevD Offline
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Loc: Bellingen NSW 2454
Originally Posted By: Flowin
I am not sure if this has been discussed before, but will ask anyway.
Has anybody heard of "atmospheric rivers" in the Australian context?
There is a body of science developing in the US about these, apparently channels of water vapour flow, and of interest to heavy rain events in California.
More info is here: https://www.esrl.noaa.gov/psd/atmrivers/
Noted in the US that they occur outside the tropics.
If it has been discussed before a link to post would help me.

You see them in the UK as well (as I suspect Aus as well) - there have been some huge floods in the mountains in the west of the UK as a result of a river lining up and not moving for some time. When I've seen it happen the moisture originates way down south and moves in a narrow corridor into the UK...
EDIT: I did a quick search and saw this: https://www.newscientist.com/article/mg21228384-300-atmospheric-rivers-caused-the-uks-worst-floods/


Edited by KevD (28/10/2017 12:12)
Edit Reason: searched and found a link...

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#1439498 - 28/10/2017 17:14 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Thanks KevD
That UK example seems to align with what Wiki says as well

"They also are the major cause of extreme precipitation events that cause severe flooding in many mid-latitude, westerly coastal regions of the world, including the West Coast of North America, Western Europe, and the west coast of North Africa."

NOOA page also has an example from Norway.
I get the impression maybe not relevant, or at least not strong for Australia, perhaps because we don't have high mountains in a west coast region. But maybe relevant for NZ?

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#1439507 - 28/10/2017 19:42 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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This paper is something that maybe of interest for this topic. http://web.maths.unsw.edu.au/~andrea/papers/Gimeno_etal_2016.pdf
Note that it is only a draft and still subject to review. It is too technical for my knowledge but some of the Weatherzone community may understand it.
Seems to say that AR are infrequent in Australia, see page 15, and not consistent location.
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#1440917 - 10/11/2017 08:23 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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The MIMIC TPW version 2 which is an experimental global product of total precipitable water is useful to see ESTIMATES of the concentration of atmospheric water movements. This link presents a global scale image, and the site also allows a view of Australia region. I emphasise ESTIMATES water movement because it is a hybrid of Satellite post processed data and model data.
http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5
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#1440922 - 10/11/2017 09:28 Re: Atmospheric Rivers [Re: Flowin]
Blair Trewin Offline
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A northwest cloud band is indeed the approximate Australian equivalent - what you're looking for is a mechanism to transport large quantities of moisture from the tropics/subtropics to higher latitudes. The parts of the world where they're most prominent tend to be ones where there's significant topography on or near the west coast.

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#1440924 - 10/11/2017 09:47 Re: Atmospheric Rivers [Re: Blair Trewin]
Kino Offline
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Originally Posted By: Blair Trewin
A northwest cloud band is indeed the approximate Australian equivalent - what you're looking for is a mechanism to transport large quantities of moisture from the tropics/subtropics to higher latitudes. The parts of the world where they're most prominent tend to be ones where there's significant topography on or near the west coast.


Cheers Blair! grin

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#1441368 - 16/11/2017 22:03 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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I agree water movement in vapour transport is an influence.
So would the upcoming wet period forecast for Qld be an AR event or something similar?
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#1441374 - 16/11/2017 22:33 Re: Atmospheric Rivers [Re: Flowin]
Greenyellow dawn Offline
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Originally Posted By: Flowin
NOOA page also has an example from Norway.
I get the impression maybe not relevant, or at least not strong for Australia, perhaps because we don't have high mountains in a west coast region. But maybe relevant for NZ?


Yep, indeed, remembered a few years ago for the pure curiosity of it, I typed into google the wettest places in the world, after learning that death valley in the states was the hottest and driest. Apparently this Milford Sound on New Zealand's south island is the wettest place on earth. Seemed to be located in mountains on the west coast of their south island.

https://en.wikipedia.org/wiki/Milford_Sound#Climate

Man oh hell, they get almost half of Sydney's yearly rainfall every month.

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#1441379 - 16/11/2017 22:50 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Beautiful area in south NZ. I went to Doughtful sound nearby to Milford sound about ten years ago. Found it amazing the environment that develops that far south with high rainfall
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#1441381 - 16/11/2017 23:00 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Atmospheric Rivers would imply the convergence of airstreams.

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#1441383 - 16/11/2017 23:04 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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The recent ECMWF rain forecasts for 6-10 day period from now look like offering a moisture feed from tropics for western Qld
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#1441385 - 16/11/2017 23:05 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
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Originally Posted By: Seira
Atmospheric Rivers would imply the convergence of airstreams.


Agree with that
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#1441532 - 17/11/2017 21:41 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Latest water vapour images suggesting increasing moisture feed from tropics
http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5
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#1441535 - 17/11/2017 22:06 Re: Atmospheric Rivers [Re: Greenyellow dawn]
Kino Offline
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Originally Posted By: Greenyellow dawn
Originally Posted By: Flowin
NOOA page also has an example from Norway.
I get the impression maybe not relevant, or at least not strong for Australia, perhaps because we don't have high mountains in a west coast region. But maybe relevant for NZ?


Yep, indeed, remembered a few years ago for the pure curiosity of it, I typed into google the wettest places in the world, after learning that death valley in the states was the hottest and driest. Apparently this Milford Sound on New Zealand's south island is the wettest place on earth. Seemed to be located in mountains on the west coast of their south island.

https://en.wikipedia.org/wiki/Milford_Sound#Climate

Man oh hell, they get almost half of Sydney's yearly rainfall every month.


Wettest on earth? Cherapunji in India gets 10000mm a year as can Bellenden Kerr in QLD.

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#1441537 - 17/11/2017 22:09 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
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Originally Posted By: Flowin
Originally Posted By: Seira
Atmospheric Rivers would imply the convergence of airstreams.


Agree with that


They refer to the mass transport of moisture in the atmosphere leading to major rainfall events.

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#1441540 - 17/11/2017 22:29 Re: Atmospheric Rivers [Re: Kino]
Flowin Offline
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Originally Posted By: Kino
Originally Posted By: Flowin
Originally Posted By: Seira
Atmospheric Rivers would imply the convergence of airstreams.


Agree with that


They refer to the mass transport of moisture in the atmosphere leading to major rainfall events.


Agree with that too

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#1441543 - 18/11/2017 00:25 Re: Atmospheric Rivers [Re: Kino]
Greenyellow dawn Offline
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Originally Posted By: Kino
Wettest on earth? Cherapunji in India gets 10000mm a year as can Bellenden Kerr in QLD.


10,000 mm? Wow, simply amazing... to have that amount of rain per year, absolutely amazing that not everything in such a place would have washed away from such a huge amount of water. ;P

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#1441549 - 18/11/2017 06:25 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
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Originally Posted By: Wikipedia
Rainfall
The rain gauge at its summit records an annual average rainfall of 8,312 mm (327.2 in), making it the wettest meteorological station in Australia. It also holds the record for the highest rainfall in a calendar year of 12,461 mm (490.6 in) in 2000 and the highest rainfall in Australia for a calendar month of 5,387 mm (212.1 in) in January 1979.[4]

In 2006, the mountain received more rainfall – 9,800 mm (390 in) – than any other part of Australia.[5] This was primarily due to two severe tropical cyclones passing close to the mountain. In 2010, Queensland's wettest year on record, the top station on the mountain recorded 12,438.4 mm (489.70 in), just under the 2000 record.


Quote:
The city's yearly rainfall average stands at 11,777 millimetres (463.7 in). This figure places it behind only nearby Mawsynram, Meghalaya, whose average is 11,873 millimetres (467.4 in). Cherrapunji receives both the southwest and northeast monsoonal winds, giving it a single monsoon season.

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#1441550 - 18/11/2017 07:13 Re: Atmospheric Rivers [Re: Flowin]
Wave Rider Offline
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I reckon there would definitely be places in the world that exceed 10,000mm and they just aren't recorded. Places that get constant westerly trades come to mind such as near in the west of NZ as mentioned. Milford Sound gets over 6000mm per year and it's at sea level so I reckon some of the mountains above that area could get double that rainfall.

Another place that comes to mind is the west coast of Chile below say 45°S. The west coast of Chile also happens to be the driest place in the world..
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#1441650 - 19/11/2017 00:35 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Originally Posted By: Kino
Originally Posted By: Flowin
Originally Posted By: Seira
Atmospheric Rivers would imply the convergence of airstreams.


Agree with that


They refer to the mass transport of moisture in the atmosphere leading to major rainfall events.


Agree with that too

There are a number of ways it can be expressed. In any case, a wind and temperature gradient is likely needed, otherwise there would be no movement at all.

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#1441719 - 19/11/2017 21:59 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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I think atmospheric rivers are a bit more specific than difference between no movement or some movement whether that be wind and temp gradient or other movement driver. My reading is that AR is a concentrated air transport of water vapour....vis vis 'flow' for long distance. And seems to be for tropics source to destination at mid latitudes or further from equator?
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#1441721 - 19/11/2017 22:13 Re: Atmospheric Rivers [Re: Flowin]
Blair Trewin Offline
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There are four parts of the world where average annual rainfalls above 10000mm have been sustained over reasonable periods of time - the region around Cherrapunji in northeast India, the windward side of a mountain in Hawaii, the west side of the Southern Alps in New Zealand (there's a gauge at about 1000m out the back of Hokitika which averages in the 11000s), and the mountains along the Pacific coast of Colombia. Which one actually comes out on top depends on which averaging period you use.

New Zealand have done some field studies with short-term gauges which suggest that rainfall in the mountains around Milford Sound reaches over 13000mm in places.

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#1441722 - 19/11/2017 22:20 Re: Atmospheric Rivers [Re: Flowin]
Homer Offline
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Fascinating stuff Blair, and incredible averages.

I was thinking....... aren't there places in Japan that can get over 10 metres of snow during winter? Would this not equate to 10 000 mm's of rain re the 1mm rain = 1 cm snow calc? Maybe these are rarer occurrences and the averages are therefore lower.
This is not a question to you Blair, but one to anyone in general.


Edited by Homer (19/11/2017 22:25)

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#1441724 - 19/11/2017 22:33 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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For atmospheric rivers it seems that the ultimate water that is at the receiving end is high, whether that be rain or snow.
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#1441727 - 19/11/2017 22:47 Re: Atmospheric Rivers [Re: Homer]
scott12 Offline
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Originally Posted By: Homer
Fascinating stuff Blair, and incredible averages.

I was thinking....... aren't there places in Japan that can get over 10 metres of snow during winter? Would this not equate to 10 000 mm's of rain re the 1mm rain = 1 cm snow calc? Maybe these are rarer occurrences and the averages are therefore lower.
This is not a question to you Blair, but one to anyone in general.


Homer ..If you were to melt a metre thick layer of snow,you could end up with as little as 10cm of water if it were fresh powder though more water ,of course, if it were older more compacted snow..a snow drift will be mostly made up of air..

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#1441729 - 19/11/2017 22:49 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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No doubt fluid dynamics at play. Air and water movement are both fluids dynamics topics. But when it involves both air and water, or 'coupling' it is significantly more complex


Edited by Flowin (19/11/2017 22:49)
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#1441734 - 19/11/2017 23:19 Re: Atmospheric Rivers [Re: Wave Rider]
Flowin Offline
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Originally Posted By: Wave Rider
I reckon there would definitely be places in the world that exceed 10,000mm and they just aren't recorded. Places that get constant westerly trades come to mind such as near in the west of NZ as mentioned. Milford Sound gets over 6000mm per year and it's at sea level so I reckon some of the mountains above that area could get double that rainfall.

Another place that comes to mind is the west coast of Chile below say 45°S. The west coast of Chile also happens to be the driest place in the world..


Aligns to my thinking that AR are what can deliver water to well south of Tropic of Capricorn or north of Tropic of Cancer.
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#1441794 - 20/11/2017 21:12 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Originally Posted By: Flowin
The MIMIC TPW version 2 which is an experimental global product of total precipitable water is useful to see ESTIMATES of the concentration of atmospheric water movements. This link presents a global scale image, and the site also allows a view of Australia region. I emphasise ESTIMATES water movement because it is a hybrid of Satellite post processed data and model data.
http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5

As a 'gauge' of current situation, the moisture north to south in latest water vapour products suggests a tropics to sub tropics attraction
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#1441796 - 20/11/2017 21:19 Re: Atmospheric Rivers [Re: Flowin]
Blair Trewin Offline
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One 'advantage' that NZ has relative to Chile (or Tasmania) is that it's upstream of an area of relatively warm ocean (the Tasman) so the westerly flow can draw on more moisture.

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#1441798 - 20/11/2017 21:20 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
No doubt fluid dynamics at play. Air and water movement are both fluids dynamics topics. But when it involves both air and water, or 'coupling' it is significantly more complex

It might be more complex (re: coupling), however it is still there to be understood. And just because something is known does not necessarily mean it is understood well.

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#1441799 - 20/11/2017 21:24 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Agree with coupling complexity.
And that South Island NZ seems to be well placed to get what is shed from Australia, like remnants of TC Debbie earlier this year
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#1441804 - 20/11/2017 22:06 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
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Originally Posted By: Seira
Originally Posted By: Flowin
No doubt fluid dynamics at play. Air and water movement are both fluids dynamics topics. But when it involves both air and water, or 'coupling' it is significantly more complex

It might be more complex (re: coupling), however it is still there to be understood. And just because something is known does not necessarily mean it is understood well.

I also agree that what known vs what is understood are two different levels of wisdom about influences on what the sky delivers.
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#1441900 - 21/11/2017 17:05 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Originally Posted By: Seira
Originally Posted By: Flowin
No doubt fluid dynamics at play. Air and water movement are both fluids dynamics topics. But when it involves both air and water, or 'coupling' it is significantly more complex

It might be more complex (re: coupling), however it is still there to be understood. And just because something is known does not necessarily mean it is understood well.

I also agree that what known vs what is understood are two different levels of wisdom about influences on what the sky delivers.

I think an important question to ask (for those interested in whatever this phenomenon entails) is:

What is it about "Atmospheric Rivers" that makes them unique and different from other known and/or understood features...? What makes them stand out in their own way?


Edited by Seira (21/11/2017 17:06)

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#1441919 - 21/11/2017 20:18 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Depends on their significance for Australia which is where I started with this.
Elsewhere where AR is recognised as significant flow of water onto land AR events have directed focus to way we measure, and forecast. This is an interesting read.

http://journals.ametsoc.org/doi/pdf/10.1175/BAMS-D-15-00245.1?download=true

My perspective is for the hydrology. I learned that water in the sky evaporates from land or water. I know the land to ocean movement of water, and am keen to better know the ocean to land movement


Edited by Flowin (21/11/2017 20:19)

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#1441941 - 22/11/2017 00:39 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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I can understand why ARs might not be so well-recognised in Australia - less high terrain in comparison to some other countries.

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#1442260 - 24/11/2017 19:49 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Yes lack of high terrain could be a likely reason for not much recognition in Oz.
Possibly also erratic frequency and location or more widely dispersed landfall rain masking their influence?
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#1442273 - 24/11/2017 21:49 Re: Atmospheric Rivers [Re: Seira]
Kino Offline
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Originally Posted By: Seira
I can understand why ARs might not be so well-recognised in Australia - less high terrain in comparison to some other countries.


They are well recognised? NW Cloud bands and their impacts on rainfall are well known.

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#1442274 - 24/11/2017 21:58 Re: Atmospheric Rivers [Re: Flowin]
ashestoashes Offline
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http://forum.weatherzone.com.au/ubbthreads.php/topics/5592/2
An old link to a discussion on north west cloud bands.

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#1442276 - 24/11/2017 22:07 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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North west moisture feed recognised as AR in this paper.

http://web.maths.unsw.edu.au/~andrea/papers/Gimeno_etal_2016.pdf

I had posted this earlier on page 1 of this topic but link was not live.

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#1442277 - 24/11/2017 22:12 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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And still not live. Copy to your browser.
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#1442281 - 24/11/2017 23:15 Re: Atmospheric Rivers [Re: Kino]
Seira Offline
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Originally Posted By: Kino
Originally Posted By: Seira
I can understand why ARs might not be so well-recognised in Australia - less high terrain in comparison to some other countries.


They are well recognised? NW Cloud bands and their impacts on rainfall are well known.


...I understand North-West Cloud-Bands are well recognised. If people wish to think of them as a version of ARs, then fine smile .


Edited by Seira (24/11/2017 23:19)

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#1442283 - 25/11/2017 05:56 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
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It’s not “people wishing to think that” at all; they’re scientifically recognised as being so?

Did you miss this quote from Blair?

Originally Posted By: Blair Trewin
A northwest cloud band is indeed the approximate Australian equivalent - what you're looking for is a mechanism to transport large quantities of moisture from the tropics/subtropics to higher latitudes. The parts of the world where they're most prominent tend to be ones where there's significant topography on or near the west coast.

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#1442305 - 25/11/2017 13:48 Re: Atmospheric Rivers [Re: Kino]
Seira Offline
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Originally Posted By: Kino
It’s not “people wishing to think that” at all; they’re scientifically recognised as being so?

Did you miss this quote from Blair?

Originally Posted By: Blair Trewin
A northwest cloud band is indeed the approximate Australian equivalent - what you're looking for is a mechanism to transport large quantities of moisture from the tropics/subtropics to higher latitudes. The parts of the world where they're most prominent tend to be ones where there's significant topography on or near the west coast.

No, I didn’t miss what was said – I said “if people wish” because if an Integrated Water-Vapour Transport can be called either a NWCB or an AR, then we have an option. Call it either or, in a given context.

No longer interested in this line of discussion. Thanks.


Edited by Seira (25/11/2017 13:58)

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#1442502 - 27/11/2017 21:14 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Does not matter what phenomenon labelling is preferred. North west cloud bands was a previous topic circa 2007? recognised on Weatherzone forums and BoM have a Webpage on it. Much of that predates more recent literature on atmospheric rivers, and you will find more literature internationally on ARs than NWCBs. BoM also have a page on ARs.
So I am not interested in the labels, but rather the concept of integrated water vapour transport from ocean onto land. My impression is IVWT in concentrated streams onto Australia is more complex than other classic AR situations around the world. Perhaps somewhat dispersed in location and time. Nonetheless probably not absent. So whatever influence AR or AR-"like" events have it is possibly more than north west cloud bands and would include some other recurrences of moisture feed onto land as well.
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#1442510 - 27/11/2017 21:43 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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And I would add to what I said above, the lack of high mountains on west coast potential AR "landfall" areas seems to be factor (real or not) in why "big" precipitation is not an obvious sign seen here in Oz.
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#1443322 - 02/12/2017 15:09 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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The last 24 hrs on mimic-TPT v2 shows interesting concentration of atmospheric precipitable water vapour movements.

http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5

TC Dahlia in north west doing her dance, and trough through Eastern Australia being fed by gulf of Carpentaria maybe? And certainly coral sea feed. Perhaps an AR like moisture flow south of about Brisbane latitude?

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#1444421 - 09/12/2017 12:47 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
So I am not interested in the labels, but rather the concept of integrated water vapour transport from ocean onto land. My impression is IVWT in concentrated streams onto Australia is more complex than other classic AR situations around the world. Perhaps somewhat dispersed in location and time. Nonetheless probably not absent. So whatever influence AR or AR-"like" events have it is possibly more than north west cloud bands and would include some other recurrences of moisture feed onto land as well.

Just take all this in smile

Some information that might be sought (regarding the Water Cycle and water-to-land movement of humidity and rain) is that the specific heat of land is very different from that of air, and more so liquid water. Liquid water has the highest specific heat (at a constant volume) followed by air and/or land/soil. Thus, when humid airstreams (or ARs) meet land, regardless of the direction in which they are travelling, they will encounter a change in the specific heat. There are other factors as well, however the reason I’m focussing on specific heat is because it is significant in determining how much heat is transported between regions (in this case, water-to-land). Land cannot retain as much heat as water, so it tends to heat up quicker, and lose it quicker.

Integrated Water-Vapour (if an internet search is done) will come up as Precipitable-Water. It is dependent on:

=> Actual Water-Vapour Pressure.
=> The Scale-Height of Water-Vapour in the Atmosphere.
=> The Air Temperature.
=> The Atomic-Mass of Water.
=> The Saturation Vapour-Pressure.

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#1444523 - 09/12/2017 20:52 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Seira, your comments on specific heat make sense to me.
I don't know enough about those vapour parameters to comment on them.
I would though further interpret that relevant parameters would then vary depending on combinations of air and water flux and heat flux (absorb, store and release) in land, water, and air, while water and air move and land stays still.
A diagram of fluxes here is forming in my mind but not sure how to lay it out


Edited by Flowin (09/12/2017 20:59)
Edit Reason: Added last bit

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#1444576 - 10/12/2017 21:29 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Seira, your comments on specific heat make sense to me.
I don't know enough about those vapour parameters to comment on them.
I would though further interpret that relevant parameters would then vary depending on combinations of air and water flux and heat flux (absorb, store and release) in land, water, and air, while water and air move and land stays still.
A diagram of fluxes here is forming in my mind but not sure how to lay it out

If I get a better idea of what you do understand, I'll know what I don't necessarily need to post smile .

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#1444676 - 12/12/2017 20:17 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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What I understand goes along the lines the following:

Heat flux, that being absorb store release, is an influence in driving movements of air and water and exchanging heat between air, water and land.

In liquid phase Rain onto land has a long and slow path back to ocean if that water gets to ocean at all, or is otherwise lost to other pathways. Such diversions can be as water back to air as Evap directly or transpired through vegetation, other take losses consumed or displaced, or down into even slower groundwater systems.

It is rare to find fast water flows on land. Most water flows on land in the hydrological cycle (rare to find > 4m/s mean velocity) are slower than speed at which air can bring water from the ocean. The pathways of water on land can also be a lot longer in distance back to the ocean, compared to the pathway of ocean bringing water onto land in fast moving concentrated humid airstreams.
Summarise this as air flow is more agile to move quickly than water flow on land.

Advection (how mass/energy is carried) and dispersion (complex exchanges of same mass/energy) between air and water are to me a factor at play. Gets beyond my understanding in deep levels of this topic.

In a fluid dynamics perspective I liken (speculate / offer as an unfounded opinion) that an atmospheric river, or AR like feature is strong in advection to carry humid air, and whether rain occurs somewhere along it has dispersion at play in very complex ways. Dispersion is very complex in high turbulence environments.

I've a lot never-ending to learn on the air drivers.... And ocean drivers..
And I look forward to learning along the way... Including any credible research or opinion that changes what I do understand 😀
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#1444687 - 12/12/2017 22:15 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Hi Flowin,

That is a very pertinent and eloquent passage you have written, in your own way smile .

Originally Posted By: Flowin
Gets beyond my understanding in deep levels of this topic.

I understand/acknowledge that.


Edited by Seira (12/12/2017 22:23)

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#1444778 - 13/12/2017 22:00 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Seira, your comments on specific heat make sense to me.

Specific heat is defined as the energy required to heat one-unit mass of substance by 1 degree Celsius.

Originally Posted By: Flowin
Heat flux, that being absorb store release, is an influence in driving movements of air and water and exchanging heat between air, water and land.

Heat flux comes from the 1st Law of Thermodynamics.

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#1444779 - 13/12/2017 22:32 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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And first law of thermodynamics being conservation of energy is similar to continuity principles in water flows used in hydrology.

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#1444892 - 14/12/2017 21:51 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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It would be interesting to see another NWCB (i.e. Australian AR) traverse the continental interior in the not-to-distant future smile .


Edited by Seira (14/12/2017 21:51)

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#1444895 - 14/12/2017 22:17 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Agree. Some transfer of energy / rain from tropics to south seems imminent.
Whether that be North West Cloud Bands or other AR like feature. Time will reveal something.

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#1444897 - 14/12/2017 22:29 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Agree. Some transfer of energy / rain from tropics to south seems imminent.
Whether that be North West Cloud Bands or other AR like feature. Time will reveal something.

I wasn't thinking imminent, but anyway smile . When the longer-wave upper-trough to the SW of the sub-tropical ridge in the Bight has no where to go but north and east, then, maybe, we'll get an AR feature.

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#1444899 - 14/12/2017 22:35 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Yeah imminent probably is wrong word, inevitable some time away or maybe sooner is more what I was thinking. For ARs or AR like features i am looking for precipitable water movement tropics south to mid latitudes. Recent times have appeared to me be weak possibilities.

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#1444933 - 15/12/2017 23:58 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
For ARs or AR like features i am looking for precipitable water movement tropics south to mid latitudes.

My understanding is it is more complicated that just looking for precipitable water. I think what might be sought is large areas of higher water-vapour concentration. It is also worth noting NWCBs, are cloud bands. Atmospheric Rivers (Integrated Water-Vapour Transport) are not necessarily cloud bands. This why I conveyed I thought the Australian NWCB is a version of an AR.

Also, if one wishes to get their ideas together, a reasonable suggestion would be to write them down smile .


Edited by Seira (16/12/2017 00:03)

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#1445152 - 19/12/2017 09:09 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
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[/quote=Siera]
My understanding is it is more complicated that just looking for precipitable water. I think what might be sought is large areas of higher water-vapour concentration. It is also worth noting NWCBs, are cloud bands. Atmospheric Rivers (Integrated Water-Vapour Transport) are not necessarily cloud bands. This why I conveyed I thought the Australian NWCB is a version of an AR.

[/quote]

I agree with all of that. I would also add that generally ARs seem to be described as a tropics/sub-tropics source towards the mid-latitudes (25 deg to 45/50 deg).


Edited by Flowin (19/12/2017 09:10)
Edit Reason: tried to fix quote:(

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#1445511 - 21/12/2017 22:20 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Current total precipitable water experimental product at link below (aka quasi integrated water vapour) suggests an AR like system at play between northern NSW and NZ across the Tasman.

http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5

Moisture feed and longitude seems to be a similar mechanism as north west cloud band but a bit further east. Also concentrated water advection perhaps a bit further south?

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#1445619 - 23/12/2017 23:27 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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And another AR-like feature - of sorts - across WA-SE Australia now smile .

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#1446090 - 27/12/2017 21:05 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Anything remotely AR like appears absent at this moment.
But the satellite images of low in NW WA for visible clouds and water vapour do appear impressive. And next week ahead on synoptic charts looks like an interesting dynamic.

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#1446284 - 29/12/2017 18:58 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
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Defin looks like an AR on the backend of the ex-TC to me.

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#1447007 - 03/01/2018 00:13 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Thanks for the original MIMIC-TPW2 link Flowin smile .

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#1447346 - 05/01/2018 07:12 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Cheers Seira - good to share links to resources.
Looks like Coral sea gave NZ a dose of AR moisture feed in weather they experienced on north island in the last day or so.

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11969352

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#1449201 - 18/01/2018 13:50 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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And another AR like event for NZ at the moment.
Shows up well on MIMIC-TPW
http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5

And media reporting it as "a river of sub-tropical air"
http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=11976862

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#1452224 - 11/02/2018 19:57 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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New Zealand looks to have been getting a fair dose of atmospheric precipitable water from the tropics. Appears broad, and mass to that region it is impressive.
http://tropic.ssec.wisc.edu/real-time/mt...4hrs&anim=html5

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#1452225 - 11/02/2018 19:59 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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#1452411 - 12/02/2018 22:36 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Around mid-Jan bbowen posted about the next gen GFS model....link here.. http://forum.weatherzone.com.au/ubbthrea...he_#Post1449204


Here is an example "experimental" (not operational) output of total water, which will be of interest for AR like events...

http://data1.gfdl.noaa.gov/fvGFS/fvGFS_products.php?YMDH=2018021118&Region=global&field=tq



Edited by Flowin (12/02/2018 22:39)

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#1453993 - 23/02/2018 08:35 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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The next generation FV GFS suggesting Aus is going to pass an AR does of moisture to NZ again in about 3 to 4 days.

http://data1.gfdl.noaa.gov/fvGFS/fvGFS_products.php?YMDH=2018022206&Region=global&field=tq

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#1454008 - 23/02/2018 09:43 Re: Atmospheric Rivers [Re: Flowin]
ozone doug Offline
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Thanks for that link Flowin ,It was interesting.Have saved it .
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#1454992 - 27/02/2018 22:31 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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new GOES satellite anticipated to improve AR forecasting for USA (among a range of other expectations)

http://www.weathernationtv.com/news/five...ts-western-u-s/

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#1456739 - 12/03/2018 10:45 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Hi Flowin smile ,

After doing some more research and investigation, I believe it may be easier and more pertinent to think of ARs as "large regions and/or bodies" of higher-concentrated water-vapour, traversing a given area before some mechanism leads to rainfall...Integrated Water-Vapour Transport (IWVT) is not a realistic nor adequate representation of what ARs are if it is area-averaged (along the transit path), because it does not account for changes in tropospheric height, latitude, or changes in air pressure with distance and the like.

This is more-or-less food for thought smile , however it may help with interpretation of future AR features affecting the Australian Region.

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#1456859 - 12/03/2018 22:13 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Thanks for your post Seira. Interesting.
I understand difference between integrated water vapour transport and concentrated water stream. Eg a slow moving wide stream with good height giving large sectional area could produce high total water movement (volume/time). Whereas a concentrated stream is high water content on a particular path.
I am not sure what you mean about troposheric height, latitude, or air pressure changes. Can you elaborate on those points? Are they factors in relation to whether water vapour eventuates to rain?
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#1457041 - 13/03/2018 20:36 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Read up a bit on troposphere. Deeper at tropics becoming shallower towards poles if I understand it correctly, so that factor and latitude related?


Edited by Flowin (13/03/2018 20:36)

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#1457051 - 13/03/2018 20:53 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Read up a bit on troposphere. Deeper at tropics becoming shallower towards poles if I understand it correctly, so that factor and latitude related?

Yes. Latitude relates to the distance of weather features from the ITCZ. The higher the latitude, the greater the Coriolis Force influence.


Edited by Seira (13/03/2018 20:55)

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#1457142 - 14/03/2018 13:01 Re: Atmospheric Rivers [Re: Flowin]
Locke Offline
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What the hell just happened with the tdepth animation at CPC.

Must be a glitch.

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#1457148 - 14/03/2018 14:04 Re: Atmospheric Rivers [Re: Flowin]
Locke Offline
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Ooops posted in the wrong area. Meant to post this in the climate driver discussion.
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#1457457 - 16/03/2018 22:09 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Thanks for your post Seira. Interesting.
I understand difference between integrated water vapour transport and concentrated water stream. Eg a slow moving wide stream with good height giving large sectional area could produce high total water movement (volume/time). Whereas a concentrated stream is high water content on a particular path.

I will acknowledge language or grammatical errors/typos, but I'm finding it difficult interpreting the above.

There is potentially rather a lot of messy theoretical stuff/or novel ideas in this dialogue which may also need clarification.

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#1457459 - 16/03/2018 22:34 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Ok Seira. Take#2
I was attempting to describe the difference between flux and concentration.
I guess I did not explain it well🙃

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#1457818 - 18/03/2018 20:35 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Ok Seira. Take#2
I was attempting to describe the difference between flux and concentration.
I guess I did not explain it well🙃


Ok smile .

My understanding is flux is usually from one region (in space and time) to another, involving a reason to transport energy from one to the other. Concentration would be density (units of some substance per a given volume).

I see no issue with using Atmospheric Rivers as a descriptive idea smile ...however beyond that (into theoretical realms) it can become tedious/messy. My impression anyway.


Edited by Seira (18/03/2018 20:42)

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#1458264 - 21/03/2018 14:03 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
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regarding your comment Seira "I see no issue with using Atmospheric Rivers as a descriptive idea smile "

I agree if you're seeking a clear definition. Similar to East Coast Lows many people want to label any low off the east coast as an ECL, but I understand that BoM do have some criteria for ECLs.

Back to ARs. The American Meteorological Society have put some definition on AR extents "Average width is based on atmospheric river boundaries defined by vertically integrated water vapor transport (IVT; from surface to 300 hPa) lateral boundary threshold of 250 kg m−1 s−1. Depth corresponds to the altitude below which 75% of IVT occurs. The total water vapor transport (a.k.a. flux) corresponds to the transport along an atmospheric river, bounded laterally by the positions of IVT = 250 kg m−1 s−1 and vertically by the surface and 300 hPa.".
Link: http://glossary.ametsoc.org/wiki/Atmospheric_river
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#1458617 - 23/03/2018 21:09 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
The American Meteorological Society have put some definition on AR extents "Average width is based on atmospheric river boundaries defined by vertically integrated water vapor transport (IVT; from surface to 300 hPa) lateral boundary threshold of 250 kg m−1 s−1. Depth corresponds to the altitude below which 75% of IVT occurs. The total water vapor transport (a.k.a. flux) corresponds to the transport along an atmospheric river, bounded laterally by the positions of IVT = 250 kg m−1 s−1 and vertically by the surface and 300 hPa.".
Link: http://glossary.ametsoc.org/wiki/Atmospheric_river

Hi Flowin smile ,

Do you understand the glossary's description? Also, bear in mind it’s for the northern hemisphere.

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#1458708 - 24/03/2018 12:34 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
regarding your comment Seira "I see no issue with using Atmospheric Rivers as a descriptive idea smile "

I agree if you're seeking a clear definition. Similar to East Coast Lows many people want to label any low off the east coast as an ECL, but I understand that BoM do have some criteria for ECLs.

My understanding is that without clear definitions, there is no science!


Edited by Seira (24/03/2018 12:38)

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#1459299 - 27/03/2018 00:53 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Seira, agree science needs clear definitions. And along the way to getting to those clear definitions some vague and evolving definitions from early work of scientists with an idea informed with observational experience of "weather" makes it all the more interesting smile

Regarding my understanding of the "North American" AMS glossary it is something like,
A width and depth is needed to define spatial "extent" (cross section of the "weather system")
Width is defined by contours of the product of concentration kg/m3 and speed m/s. Something similar to flux per unit width and unit depth of a cross section.
Depth is defined by height that is below approx 75% of total depth-integrated precipitable water vapour up to 300 hPa
If my understanding is incorrect then I am happy to be corrected.:)👍


Edited by Flowin (27/03/2018 00:58)
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#1459597 - 28/03/2018 19:33 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
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Originally Posted By: Flowin
Seira, agree science needs clear definitions. And along the way to getting to those clear definitions some vague and evolving definitions from early work of scientists with an idea informed with observational experience of "weather" makes it all the more interesting smile

Regarding my understanding of the "North American" AMS glossary it is something like,
A width and depth is needed to define spatial "extent" (cross section of the "weather system")
Width is defined by contours of the product of concentration kg/m3 and speed m/s. Something similar to flux per unit width and unit depth of a cross section.
Depth is defined by height that is below approx 75% of total depth-integrated precipitable water vapour up to 300 hPa
If my understanding is incorrect then I am happy to be corrected.:)👍

I have little issue with what you have conveyed as your understanding....however that is not the reason I asked. The point I have been trying to get at is, as far as I can tell, water vapour does not have a depth in the atmosphere -- it has a concentration, which can be measured in kilograms per unit volume (e.g. cubic metre)....precipitable water is a theoretically derived equation, which is not the same as integrated water-vapour transport [IWVT],....and I find it difficult reconciling IWVT with the idea of integration itself.

My understanding is integration requires:
=> A equation that can be integrated (with some variable).
=> Taking the integral of that equation (over a definite range, e.g. X=1 to X=0).
=> Plugging figures into the integrated equation (variable X) over that definite range to get an outcome.

That is my insight smile .


Edited by Seira (28/03/2018 19:43)

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#1459641 - 29/03/2018 08:55 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Seira, thanks. I think I now understand the point you were raising smile , and yes water vapour does not have a depth in the atmosphere.

I agree an equation that can be integrated with respect to a variable and over a defined range is needed for mathematical completeness.
I simply think of integration when in relation to matters such as concentration or water flow as "aggregate", "total", or "sum".
E.g. concentration in kg/m3 multiplied by a defined volume m3 yields kg. Similarly flow in m3/s multiplied by a defined time period yields m3. In that way of describing it you can replace words "multiplied by" with "integrated over".

Water vapour as a concentration kg/m3 integrated with the depth of the atmosphere (assuming some upper level can be defined above which there is minimal water vapour) yields kg/m2 which I understand to be total precipitable water. It appears commonly expressed as depth in mm assuming density of water as 1000 kg/m3 (but more strictly TPW should be said as units of kg/m2).

If that "total depth" of precipitable water is moving (assuming laterally), it is a transport of TPW in kg/m2 multiplied by speed in m/s which yields kg/m/s (or kg m-1 s-1).

So yes TPW is not the same as IWVT as TPW does not have the movement component, whereas IWVT does have the movement component.

I hope that makes sense, does not contain errors, and is relevant to your point.

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#1459776 - 30/03/2018 13:55 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7447
Loc: Central Adelaide Hills
I can understand where you're going, smile .... perhaps this will help as well:

Depending on where you are....water-vapour makes up between 1 and 4% of the mass of air by volume, at sea-level. In that sense you are accurate in saying, more-or-less, there would have to be a cut-off minimum concentration at which this gas determines the total integration [with altitude] of IWV. However, because water-vapour can be so variable in the troposphere, it is difficult, unless direct measurements are made, to say whether there will be just one cut-off in the vertical [and horizontal], or more than one. If there is more than one, the integral would become fragmented and incomplete....without such measurements [in space and time] this, realistically, cannot be ruled out.

So, in a nutshell, IWVT has to take into account variations in the integral with space and time, which, I'd think, would make it far more complex.

The other thing one would have to be careful about is calling every little "feature" on a weather map an Atmospheric River, because its water-vapour concentration exceeds -- however confined or narrow -- that of the minimum cut-off.


Edited by Seira (30/03/2018 13:59)

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#1460575 - 03/04/2018 07:51 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 439
Loc: Pinjarra Hills, Qld
I agree the vertical integration of water vapour is not straight forward, nonetheless some attempt to estimate total precipitable water helps to get a feel for water in the atmosphere, better than say water vapour loop from Satellite image.

Originally Posted By: Seira

The other thing one would have to be careful about is calling every little "feature" on a weather map an Atmospheric River, because its water-vapour concentration exceeds -- however confined or narrow -- that of the minimum cut-off.


I agree also an AR is not just any feature showing "higher" water vapour concentration.
I think the American Meteorological Society definition part way helps to clarify some definition for an Atmospheric River - which I might simplify to "sufficient total depth of water content in the atmosphere, combined with movement, and spatial extent such that the feature can transport a lot of water"


Edited by Flowin (03/04/2018 07:52)

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#1460761 - 03/04/2018 19:58 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7447
Loc: Central Adelaide Hills
I find your resilience with regard to this discussion quite admirable Flowin smile . Despite discrepancies there might be in our perspectives smile .

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#1460767 - 03/04/2018 20:12 Re: Atmospheric Rivers [Re: Seira]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 439
Loc: Pinjarra Hills, Qld
Originally Posted By: Seira
I find your resilience with regard to this discussion quite admirable Flowin smile . Despite discrepancies there might be in our perspectives smile .

Fair comment Seira. Going back to where I started from
Originally Posted By: Flowin

Has anybody heard of "atmospheric rivers" in the Australian context?

Definition of the feature, or say AR event criteria clarification is important.
I have appreciated your questioning, and have learnt along the way😀

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#1461481 - 11/04/2018 20:16 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7447
Loc: Central Adelaide Hills
Originally Posted By: Flowin
I have appreciated your questioning, and have learnt along the way😀

And it's reciprocated smile !

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#1461696 - 13/04/2018 21:23 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 439
Loc: Pinjarra Hills, Qld
Another observation I have from literature on ARs in research effort from California seems to me to identify more occurrences of ARs in winter.
I am yet to explore whether that means anything for AR like weather events for Australia.

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#1461721 - 14/04/2018 10:09 Re: Atmospheric Rivers [Re: Flowin]
retired weather man Offline
Weatherzone Addict

Registered: 01/07/2007
Posts: 4532
Loc: Wynnum
My guess is our version would be Autumn to late Winter NW cloud bands, many of which used to spawn ECL's and don't seem to be as frequent these days.
_________________________
Wyn Nth 2018-Jan12.2(158),Feb264.4(146),Mar217.0(126),Apr65.8(96),May46.0(100),Jun30.0(74),YTD634.4(701.1),

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#1462062 - 19/04/2018 06:30 Re: Atmospheric Rivers [Re: Flowin]
wilyms Offline
Weather Freak

Registered: 06/03/2013
Posts: 145
Loc: Roma, Qld
News.com just published something useful and relevant to this thread!

http://www.news.com.au/technology/enviro...e33525623c9302f

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#1465237 - 08/06/2018 13:45 Re: Atmospheric Rivers [Re: Flowin]
Kino Offline
Weatherzone Addict

Registered: 10/08/2017
Posts: 2173
Loc: Wollongong, NSW, Aus
First atmospheric river for the Winter Season already dumping across the country!

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