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#1442273 - 24/11/2017 21:49 Re: Atmospheric Rivers [Re: Seira]
Kino Offline
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Registered: 10/08/2017
Posts: 1617
Loc: Wollongong, NSW, Aus
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 Online   content
Weather Freak

Registered: 22/10/2017
Posts: 78
Loc: Voyager Point (South West Sydn...
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weatherzone Addict

Registered: 10/08/2017
Posts: 1617
Loc: Wollongong, NSW, Aus
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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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Models are for estimating and gauges are for knowledge.

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#1442510 - 27/11/2017 21:43 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
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Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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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Models are for estimating and gauges are for knowledge.

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#1443322 - 02/12/2017 15:09 Re: Atmospheric Rivers [Re: Flowin]
Flowin Offline
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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 😀
_________________________
Models are for estimating and gauges are for knowledge.

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#1444687 - 12/12/2017 22:15 Re: Atmospheric Rivers [Re: Flowin]
Seira Offline
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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
Weather Freak

Registered: 15/10/2017
Posts: 222
Loc: Pinjarra Hills, Qld
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
Meteorological Motor Mouth

Registered: 27/08/2003
Posts: 7278
Loc: Adelaide Hills.
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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