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BigDon
2008-Dec-31, 04:35 PM
I was informed once, way back in high school, that if Earth didn't have contenants we would be banded like a gas giant and that winds would likely pick up to the point that the interface between ocean and atmosphere would be "blurred" in a perpetual storm. (Though I imagine a small scale "Red Spot" somewhere would be more the case.)

Would this be an accurate assessment?

Durakken
2008-Dec-31, 04:48 PM
there is a simple problem with that statement... the thing that drives much of our weather system also creates the land masses so if there are no landmasses one should also assume that the processes involved in creating them have stopped thus it really wouldn't work the same way...

And any process that would be great enough to cause what you are describing would have taken effect by now... with or without the land there.

On thing is for certain though wind would be a lot faster so the storm systems we know have are reduced by quite a bit thanks to the land but I'm not sure to what extent

Chunky
2008-Dec-31, 04:52 PM
wind does blow faster over water. no obstructions to slow it down, no trees.

grant hutchison
2008-Dec-31, 05:08 PM
I haven't kept up with this recently, but the banded appearance of the gas giants has been attributed to their significant internal heat driving deep convection which keeps the poles as warm as the equator. Whereas the Earth, without continents, would still have a significant temperature gradient between pole and equator which should drive latitudinal winds, as it does now.
I've seen it said that landfall is what kills hurricanes: without warm surface water they lose their energy source. So absent continents might allow hurricanes to grow larger and stronger over time. However, Coriolis should still (eventually) divert them to higher latitudes, leading to their ultimate decay over colder surface water.

So I think I'm having trouble believing this one, at present.

Grant Hutchison

Gigabyte
2008-Dec-31, 07:53 PM
Looking at the atmosphere from space we are indeed banded, with constant wind currents and cyclones, over the oceans. Look at the Pacific ocean from the right point in space, and the earth is all water, with a few tiny islands.

cran
2008-Dec-31, 11:58 PM
I was informed once, way back in high school, that if Earth didn't have contenants we [the surface] would be [appear] banded like a gas giant and that winds would likely pick up to the point that the interface between ocean and atmosphere would be "blurred" in a perpetual storm. (Though I imagine a small scale "Red Spot" [more like blue/white] somewhere would be more the case.)

Would this be an accurate assessment?

yes.


there is a simple problem with that statement... the thing that drives much of our weather system also creates the land masses so if there are no landmasses one should also assume that the processes involved in creating them have stopped thus it really wouldn't work the same way...

rubbish - the thing that drives our weather is the Sun ...

cran
2009-Jan-01, 12:05 AM
I haven't kept up with this recently, but the banded appearance of the gas giants has been attributed to their significant internal heat driving deep convection which keeps the poles as warm as the equator. Whereas the Earth, without continents, would still have a significant temperature gradient between pole and equator which should drive latitudinal winds, as it does now.
I've seen it said that landfall is what kills hurricanes: without warm surface water they lose their energy source. So absent continents might allow hurricanes to grow larger and stronger over time. However, Coriolis should still (eventually) divert them to higher latitudes, leading to their ultimate decay over colder surface water.

So I think I'm having trouble believing this one, at present.

Grant Hutchison
you might want to recheck your sources on that ... latitudinal winds (banding or zonal masses) seem prevalent wherever atmospheres occur on rotating bodies ...

grant hutchison
2009-Jan-01, 12:53 AM
you might want to recheck your sources on that ... latitudinal winds (banding or zonal masses) seem prevalent wherever atmospheres occur on rotating bodies ...Zut. :)
I confused the names, there. What I was thinking of as "latitudinal" (changing latitude) is actually "meridional" (maintaining longitude). So "latitudinal" = "zonal": winds that blow around the globe parallel to the equator. Those are the winds that (last time I looked) dominate on planets with little or no temperature gradient from pole to equator.
With an Earth-like temperature gradient across latitudes (= along meridians), we necessarily get air moving north and south, too, along density gradients.
So on such (Earth-like) worlds there are zonal masses, as you say, but each represents a convective cell containing diagonal wind systems below and aloft, with a net heat transfer towards the poles.

Condensed version:
No trade winds on Jupiter.

Grant Hutchison

Romanus
2009-Jan-01, 02:13 AM
There is an old study I read (admittedly, it was summarized in Discover) that modeled what the very early Earth might have been like (rapid rotation and no real continents), that might have led to more zonal windflow.

And how about that--I found the article:
http://findarticles.com/p/articles/mi_m1511/is_n11_v14/ai_14515761/pg_1

cran
2009-Jan-01, 12:21 PM
Zut. :)
I confused the names, there. What I was thinking of as "latitudinal" (changing latitude) is actually "meridional" (maintaining longitude). So "latitudinal" = "zonal": winds that blow around the globe parallel to the equator. Those are the winds that (last time I looked) dominate on planets with little or no temperature gradient from pole to equator.
With an Earth-like temperature gradient across latitudes (= along meridians), we necessarily get air moving north and south, too, along density gradients.
So on such (Earth-like) worlds there are zonal masses, as you say, but each represents a convective cell containing diagonal wind systems below and aloft, with a net heat transfer towards the poles.

Condensed version:
No trade winds on Jupiter.

Grant Hutchison

Grant, you're not normally given to rash statements -
I put it down to the New Year celebrations ...


a simplified diagram (ie, the kind of thing BigDon was told/had in mind) can be found here:
Planetary scale tropospheric systems (http://www.auf.asn.au/meteorology/section4.html)

NB - without landmasses, the equator-pole thermal gradient at surface would not be as large ...
Trade winds are easterlies (like the Polar easterlies) - ie, the dominant motion is latitudinal ...

--------



From a distance Jupiter appears to have horizontal stripes, which result from winds that shear its cloud layers into sharply defined bands. These bands circle the planet, with winds along the edges of adjacent bands blowing in opposite directions. Earth’s trade winds form a similar pattern, but Jupiter’s winds are much stronger and more stable. The strongest winds, at low latitudes near Jupiter’s equator, drive individual cloud systems 11 eastward every 24 hours. At higher latitudes the clouds alternately shift westward and eastward corresponding to the banded structure of the atmosphere, which is sculpted by these wind jets. This cloud motion indicates winds of 600 km/h (370 mph) at low latitudes with winds decreasing to tens of kilometers per hour at high latitudes.- Encarta (http://encarta.msn.com/encyclopedia_761564261_2/jupiter.html)




Letters to Editor

nature 25, 360-361 (16 February 1882) | doi:10.1038/025360b0

The Movements of Jupiter's Atmosphere

G. H. DARWIN
Top of page
Abstract

The reference to the belts of Jupiter contained in my article on the geological activity of the tides (NATURE, vol. xxv. p. 213), was perhaps superfluous, for the subject is only collaterally connected with the points there under discussion; but as Mr. Mattieu Williams has commented on what I said, I should like to make a few remarks on his letter. Notwithstanding what he says I am still inclined to hold that the time-honoured explanation of the belts of Jupiter is the true one. In that explanation the terms trade and anti-trade winds are, I conceive, used in a somewhat extended sense as a consequence of thermal causes, and without reference to the existence of a solid nucleus, a current is supposed to set upwards in equatorial regions and then to spread out into higher latitudes; here the fluid has more moment of momentum than is adapted for the latitude in which it finds itself, and accordingly moves relatively to the subjacent matter in the direction of the planet's rotation, and forms an anti-trade wind. Conversely the trade winds arise from fluid moving into lower latitudes, when it has a deficiency of moment of momentum. Such an explanation seems to serve equally to explain the unequal rotation of the surface of the sun in different latitudes, and the Jovian belts.- Nature (http://www.nature.com/nature/journal/v25/n642/abs/025360b0.html)




Rising air masses in Jupiter’s atmosphere expand north and south. The air that moves toward the equator must travel around a longer path than it originally followed, while the air that moves toward the pole travels a shorter path. These deflections give rise to alternating winds that shear Jupiter’s cloud layers into sharply defined bands. Similar mechanisms cause the trade winds of Earth, but Jupiter’s winds are much stronger and form a more stable pattern than they form on Earth.
- beyondearth2001 (http://www.geocities.com/beyondearth2001/jupiter.htm)

Whether the thermal energy is external (as for Earth) or internal (as for Jupiter) seems to have little bearing on atmospheric zones or banding:


'Jet streams' and 'trade winds' found
below the sun's surface

BY DAVID F. SALISBURY

Stanford's Solar Oscillations Investigation (SOI) group has discovered the solar equivalents of jet streams and trade winds below the sun's fiery surface...

Nevertheless, the solar scientists have also found solar features comparable to trade winds. Because it consists entirely of gas, the sun rotates much faster at the equator than at the poles. However, hidden within this differential rotation, Schou and senior research associate Alexander G. Kosovichev have found, are belts in the northern and southern hemispheres where currents flow at different speeds relative to each other. Six of these gaseous bands move slightly faster than the material surrounding them. The solar belts are more than 40,000 miles across and they contain "winds" that move about 10 miles per hour relative to their surroundings... - Stanford University News (http://news-service.stanford.edu/news/1997/september10/solarjets.html)

grant hutchison
2009-Jan-01, 02:02 PM
Grant, you're not normally given to rash statements - Well, I did tag it all with a disclaimer about not having looked at this stuff recently. :)
I accept correction about trade winds, although your references emphasis their easterly component and seem to ignore their equatorwards movement on Earth, driven by vertical convective movement at the equator and the descent of cooler air over the subtropical deserts.

We'll need to hear from BigDon whether the plain old standard circulation with significant meridional movement of air (which exists on Earth at the moment) is what he has in mind when he wrote "banded like a gas giant". I thought he was envisaging a significant change in the behaviour of air masses, and I was suggesting that the old system (sketched in your first link (http://www.auf.asn.au/meteorology/section4.html)) would persist in the absence of oceans. I'm thinking you're saying the same thing.

Is there a jovian analogue to our temperate frontal system? The repeated folding together of cold and warm air masses at mid-latitudes is driven by meridional movement of air, with a net transfer of heat towards the poles, and it constantly prevents the establishment of neat zonal banding in a broad swathe of the temperate latitudes.

Grant Hutchison

cran
2009-Jan-02, 12:19 AM
Well, I did tag it all with a disclaimer about not having looked at this stuff recently. :)
I accept correction about trade winds, although your references emphasis their easterly component and seem to ignore their equatorwards movement on Earth, driven by vertical convective movement at the equator and the descent of cooler air over the subtropical deserts. but that's one of the points I interpreted in BigDon's OP -
without landmasses, would Hadley cells persist or weaken relative to latitudinal motion?
Without topography (ie, no mountains; a world ocean), what happens to the troposphere (where most of the interesting stuff happens)?


We'll need to hear from BigDon whether the plain old standard circulation with significant meridional movement of air (which exists on Earth at the moment) is what he has in mind when he wrote "banded like a gas giant". I thought he was envisaging a significant change in the behaviour of air masses, and I was suggesting that the old system (sketched in your first link (http://www.auf.asn.au/meteorology/section4.html)) would persist in the absence of oceans. I'm thinking you're saying the same thing.ahh, but the absence of oceans is not the question, is it?

but yes - without landmasses, the change would not be significant - merely simplified ... which from the outside would show more clearly defined zonal differences - add clouds, and you get banding and persistent circulatory cells (storms) ...


Is there a jovian analogue to our temperate frontal system? The repeated folding together of cold and warm air masses at mid-latitudes is driven by meridional movement of air, with a net transfer of heat towards the poles, and it constantly prevents the establishment of neat zonal banding in a broad swathe of the temperate latitudes.

Grant HutchisonI vaguely recall mention of an analog, but I don't think it was distinctly thermal (as on Earth) - perhaps chemical?
ie, some form of zonal mixing/overturning of relatively heavier molecules (which would tend poleward) and lighter molecules (which would tend equatorward)? I'd have to hunt around for refs ...

there's little chance that the Earth could show as many bands or zones compared to the outer planets - 5 or 6 would be about it (depending on whether or not you define the ITCZ as a boundary ...)

grant hutchison
2009-Jan-02, 12:59 AM
but that's one of the points I interpreted in BigDon's OP -
without landmasses, would Hadley cells persist or weaken relative to latitudinal motion? We're still going to have a temperature gradient from pole to equator. That will still drive meridional transport, so the cells seem to me to be a fixture. As you point out, they fall out of very simple modelling.


ahh, but the absence of oceans is not the question, is it?It's not. That was a typo on my part.


but yes - without landmasses, the change would not be significant - merely simplified ... which from the outside would show more clearly defined zonal differences - add clouds, and you get banding and persistent circulatory cells (storms) ... I'm unconvinced. The lolloping interchange of air masses along the polar front is a very visible feature which prevents the formation of a linear zone boundary, and it falls out of simple models (physical and numerical) with cool poles and warm equators (or so my meteorology textbooks tell me). You can produce the same behaviour in a rotating tank of water, cooled at the centre and warmed at the rim.


there's little chance that the Earth could show as many bands or zones compared to the outer planets - 5 or 6 would be about it (depending on whether or not you define the ITCZ as a boundary ...)When we look at Jupiter and Saturn, most of the cloud we see is participating in pretty pure zonal movement, with meridional transfer mediated by eddies at the zone boundaries.
When we look at the Earth, most of the cloud we see is participating in a mixture of zonal and meridional movement. Zonal jets are small, restricted to zone boundaries, and pretty much invisible.
We have big physical differences between Earth and the gas giants which have been deployed to explain these differences in atmospheric circulation: the gas giants have no surface, limited pole-equator temperature gradient, internal heat of the same order of magnitude as solar heating, and fast rotation. None of these differences goes away if we remove Earth's continents.

So I'm still having trouble believing that the simple removal of landmasses would all but abolish the current strong meridional movement.

Grant Hutchison

aurora
2009-Jan-02, 01:25 AM
In the southern hemisphere, sailors call the ocean between the other land masses and Antartica "the roaring 40's". For good reason.

However, I wouldn't call it a "band" in the sense that the gas giants have bands.

eburacum45
2009-Jan-02, 08:43 AM
When I made this model of a fictional waterworld
http://www.orionsarm.com/downloads/panthalassa.jpg
I assumed that the absense of landmasses would allow the winds to travel much faster, so a form of banding would occur. The image does broadly agree with the banding shown on this page;
http://www.auf.asn.au/meteorology/section4.html
you have coherent bands near the equator, and wavy and incoherent bands at 45 degrees, due to the undulations in the jet stream.

However now I come to look at it the equatorial region is in fact a region of doldrums- low winds and relatively calm conditions. On a planet with no continents this region could become very stable, I think. So perhaps this region on my model should be clear and calm; perhaps on Panthalassa the doldrums are covered by a high still layer of haze.

The atmosphere circulation of a waterworld would also be affected strongly by the tilt of the world, and by the speed of rotation- you might get a waterworld with a superotating atmosphere in certain conditions, which would be fun.

grant hutchison
2009-Jan-02, 04:23 PM
When I made this model of a fictional waterworld
http://www.orionsarm.com/downloads/panthalassa.jpg
I assumed that the absense of landmasses would allow the winds to travel much faster, so a form of banding would occur. The image does broadly agree with the banding shown on this page;
http://www.auf.asn.au/meteorology/section4.html
you have coherent bands near the equator, and wavy and incoherent bands at 45 degrees, due to the undulations in the jet stream.

However now I come to look at it the equatorial region is in fact a region of doldrums- low winds and relatively calm conditions. On a planet with no continents this region could become very stable, I think. So perhaps this region on my model should be clear and calm; perhaps on Panthalassa the doldrums are covered by a high still layer of haze.And the trade winds aren't particularly strong, on average; they just blow in the same direction for days on end.
The really strong winds are associated with the westerlies of mid-latitudes, which come and go with the weather systems spawned by the polar fronts. And, interestingly for me at least, they're not that much stronger in the unimpeded reaches of the Southern Ocean than they are at corresponding latitudes in the North Atlantic and North Pacific. The Southern Ocean generates big seas, dangerous to mariners, because of the uninterrupted fetch it affords the winds: but it seems we can have a band of open ocean encircling the world, at a maximally windy latitude, without it generating perpetually howling zonal winds.

So I do wonder if additional sea-room would make much difference to the gentle trade winds.

Grant Hutchison

cran
2009-Jan-03, 01:17 AM
...I'm unconvinced. The lolloping interchange of air masses along the polar front is a very visible feature which prevents the formation of a linear zone boundary, and it falls out of simple models (physical and numerical) with cool poles and warm equators (or so my meteorology textbooks tell me). You can produce the same behaviour in a rotating tank of water, cooled at the centre and warmed at the rim.

When we look at Jupiter and Saturn, most of the cloud we see is participating in pretty pure zonal movement, with meridional transfer mediated by eddies at the zone boundaries...

Grant Hutchison
you lost me there - can you explain "lolloping interchange", and how it differs from "eddies" ...
which we find emanating from fronts in the ocean/atmosphere coupled system?

I think you might be underestimating the effect of landmasses on global weather -
not just the more extreme thermal responses to seasonal changes,
but also their ability to steer, disrupt and otherwise alter storm cells and clouds generally -
and what more persistent (undisrupted) cloud bands, coupled with the absence of polar landmasses
(and their contribution to katabatic winds) would do to insolation and OLR
(and, therefore, to the thermal gradient) ...

I also wonder if there might generally (ie, not specifically aimed at Grant) be some confusion
between "analogue" and "scale model" or "copy"?
if so, then we are somewhat at cross-purposes ...

grant hutchison
2009-Jan-03, 01:39 AM
you lost me there - can you explain "lolloping interchange", and how it differs from "eddies" ...
which we find emanating from fronts in the ocean/atmosphere coupled system? It's a matter of relative scale, as I have been trying to make clear.
The zonal flow in gas giants is dominant, with small amounts of meridional transfer at the margins, in eddy structures that have quite limited extent in latitude. The zonal flow on Earth is not dominant, because there is a large amount of meridional exchange taking place in the form of large "structures" (such as temperate weather systems and trade winds) that span many degrees of latitude.
That difference in the relative scale of meridional exchange, to my mind at least, prevents the Earth from being "belted like a gas giant", and we'd need to suppress that meridional exchange for the Earth to become "belted like a gas giant".

(This is also why I object, albeit mildly, to the references you searched out in which zonal jets on Jupiter are referred to as "trade winds". I understand that the authors of these remarks are emphasizing similarities, but they do so at the expense of obscuring differences.)

Grant Hutchison

Ara Pacis
2009-Jan-03, 11:36 AM
WRT the OP, it would be interesting to determine if the lack of continents refers merely to a lack of dry land or to a "flat" lithosphere underlying the world ocean. After all, a significant amount of heat is moved by oceanic currents that move between warmer equatorial waters and the colder northern waters. Those currents are significantly affected by lithostructures, whether they are above mean sea level or beneath it.

eburacum45
2009-Jan-03, 12:05 PM
There is a significant difference between a world with shallow oceans and no land masses, and a waterworld with a layer of water hundreds of kilometers deep. For a start the world with shallow oceans might develop continents over time. I think that according to some models the Earth had only very small continents at one time, which have grown over the passing of eons to the size that we see today.
In this Wiki article they are called 'cratons', a term that sounds familiar from my long-ago student days.
http://en.wikipedia.org/wiki/Craton#Formation

This could mean that young, earth-like worlds with a few small, isolated continents and island arcs are possible, perhaps even common.

BigDon
2009-Jan-03, 04:05 PM
Okay, thanks for the replies everybody!

Now did somebody want me to clarify a point in my original question? I thought I read that but now can't find the sentence.

cran
2009-Jan-03, 04:17 PM
(This is also why I object, albeit mildly, to the references you searched out in which zonal jets on Jupiter are referred to as "trade winds". I understand that the authors of these remarks are emphasizing similarities, but they do so at the expense of obscuring differences.)
good, then you understand what an analogue is, having just defined it ...


It's a matter of relative scale, as I have been trying to make clear. OK - so you believe in the "scale model" misconception of analogue ("all scale models are analogues, therefore all analogues are scale models") ...


The zonal flow in gas giants is dominant, with small amounts of meridional transfer at the margins, in eddy structures that have quite limited extent in latitude. That reminds of the NASA scientist who described elements of Jupiter as "... calmly spinning, but when we got there, it was chaos!" ...
there are gyres (eddies/persistent cells/storms/spots/whatever...), Rossby-like wave motions, Hadley-like convections; various motions which include a meridional component within the overall zonal flow - the zonal boundaries are more apparent/clearly definable because (among other potential causes) Jupiter does not have a solid surface ... something you already pointed out, I believe ...


The zonal flow on Earth is not dominant, because there is a large amount of meridional exchange taking place in the form of large "structures" (such as temperate weather systems and trade winds) that span many degrees of latitude. oh?
what are the maximum number of degrees latitude that you would allow a zone to occupy?
What are the minimum number of zones required to achieve "a banded appearance"?
I would think 3 is the minimum; Earth has 5 ...

at 3 zones, the average span in latitude is 60 degrees ...
Earth's zones are roughly 25, 40, 50, 40, 25 degrees latitude...

If zonal flow on Earth were not dominant, there wouldn't be zones as such - only hemispheres, with direct exchange from polar-equatorial/equatorial-polar (as occurs in oceanic boundary currents and some deep ocean currents), rather than via intermediate/temperate zones ...

zones, belts, bands (whatever one chooses to call them) simply indicate a change across latitudes of the east-west motion of air masses - no matter how strong or clearly apparent a zone might be, the meridional component of motion continues ... and does so due to pressure gradients, whether they are thermally or chemically (or any other-ly) driven ...



That difference in the relative scale of meridional exchange, to my mind at least, prevents the Earth from being "belted like a gas giant", and we'd need to suppress that meridional exchange for the Earth to become "belted like a gas giant".


Grant HutchisonThat's OK - it's not my job to convince you ...
nor yours to convince me -
it's BigDon's job to decide which replies best fit his OP question ...

grant hutchison
2009-Jan-03, 04:26 PM
Now did somebody want me to clarify a point in my original question? I thought I read that but now can't find the sentence.I suspect that would be me, here:
We'll need to hear from BigDon whether the plain old standard circulation with significant meridional movement of air (which exists on Earth at the moment) is what he has in mind when he wrote "banded like a gas giant". I thought he was envisaging a significant change in the behaviour of air masses, and I was suggesting that the old system (sketched in your first link (http://www.auf.asn.au/meteorology/section4.html)) would persist in the absence of oceans.Grant Hutchison

cran
2009-Jan-03, 04:46 PM
yes ... the point I forgot to acknowledge in the swirl of debate details ...


We'll need to hear from BigDon whether the plain old standard circulation with significant meridional movement of air (which exists on Earth at the moment) is what he has in mind when he wrote "banded like a gas giant". I thought he was envisaging a significant change in the behaviour of air masses, and I was suggesting that the old system (sketched in your first link (http://www.auf.asn.au/meteorology/section4.html)) would persist in the absence of oceans. I'm thinking you're saying the same thing.

yes, I am saying the same thing - hence the included link - but not merely persist as before, but stronger; with more water vapour (clouds) it (the sketched pattern) would be more visually apparent from space ...

grant hutchison
2009-Jan-03, 04:49 PM
That's OK - it's not my job to convince you ...
nor yours to convince me -
it's BigDon's job to decide which replies best fit his OP question ...Which is just as well, it seems. :)

The term of art for global circulation models of Earth without continents seems to be "aquaplanet", and they've been carried out fairly frequently.

Here (http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2FJCLI3874.1) is Smith et al's work from 2006 (which is the paper I was recalling). Their Waterworld isn't entirely oceanic; it has a couple of polar islands for computational reasons. They found that:
Surface winds speeds are little reduced compared to
those simulated for modern climate, despite the much
reduced meridional temperature gradient (Fig. 5). This
is likely due to the reduced surface friction from the
removal of the land. Higher up, the jet streams (not
shown) are little changed in position or strength from
those found in the current climate simulation as the
shallow meridional temperature gradient at the surface
steepens at higher altitudes.Atmospheric energy transport from equator to pole remained about the same, despite the reduced gradient.

I also Googled up a more recent model by Marshall et al (http://paoc.mit.edu/paoc/papers/aqua.pdf) (2.3MB pdf), with different ocean parameters, which results in a much steeper pole-equator temperature gradient, but which nevertheless concludes:
The atmospheric
state is reminiscent of that of the present climate.
It comprises baroclinically unstable subtropical
jets, a Hadley circulation, midlatitude surface westerlies,
and trade winds in the Tropics.So Earth modelled without continents results in a very similar state to what we see today: there's no evidence of continuously roaring zonal storms in these models, or in others I recall dipping into in the past.

I think that provides a clear answer to BigDon's question.

Grant Hutchison

BigDon
2009-Jan-03, 05:38 PM
My question is answered.

Thank you, gentlemen.

cran
2009-Jan-03, 05:56 PM
I also Googled up a more recent model by Marshall et al (http://paoc.mit.edu/paoc/papers/aqua.pdf) (2.3MB pdf), with different ocean parameters, which results in a much steeper pole-equator temperature gradient, but which nevertheless concludes:So Earth modelled without continents results in a very similar state to what we see today: there's no evidence of continuously roaring zonal storms in these models, or in others I recall dipping into in the past.

I think that provides a clear answer to BigDon's question.

Grant Hutchison
on the contrary, from a quick reading the paper goes into some detail about the zonal flows, and the differences between them ...

it describes an ocean-atmosphere coupled system with 5 zones, but an isolated atmosphere with only 3 - the polar easterlies have gone ...

it describes the westerly mid-lats as dominated by evaporation (cloud formation), and Ferrel cells (though extending to higher latitudes) and mass transport as eddy-driven ...

the easterly tropics as dominated by precipitation and Hadley cells, and without an ENSO variation (therefore no weakening or reversals on decadal scales), and bounded by zonal jets ...

and the poles (without easterlies) dominated by precipitation and persistent ice caps reaching to 55 deg latitude ...

grant hutchison
2009-Jan-03, 06:06 PM
You'll note I said "similar", not "identical"; the authors list the points of similarity in my quotation. And I referred specifically to the absence of continuously roaring zonal storm winds when I suggested BigDon's question had been answered.

I'm sorry if you think I've misled BigDon with anything I've said. But having given the links to relevant papers, I believe I can probably bow out now and let him make up his own mind with your guidance.

Grant Hutchison

mugaliens
2009-Jan-03, 07:05 PM
On thing is for certain though wind would be a lot faster so the storm systems we know have are reduced by quite a bit thanks to the land but I'm not sure to what extent

That's not certain at all. In fact, observation shows quite the opposite. Not only is 75% of our planet's surface covered in water, but vast expanses, including areas reaching well over half way around the planet, do not give rise to banshee winds.

Furthermore, I doubt that the absense of land masses would give rise to increased winds at all. Look at Mars - it's winds are faster, on average, than Earth's. Of course many factors, including density, are going on, there, so it's not a fair comparison.

What's noteworthy, however, is the fact that the highest non-cyclonic winds, 231 mph worth, occur over land (http://www.mountwashington.org/about/visitor/recordwind.php). Sustained non-cyclonic wind speeds over land, even over wide areas, routinely outpace their ocean cousins.

Ara Pacis
2009-Jan-03, 08:46 PM
What's noteworthy, however, is the fact that the highest non-cyclonic winds, 231 mph worth, occur over land (http://www.mountwashington.org/about/visitor/recordwind.php). Sustained non-cyclonic wind speeds over land, even over wide areas, routinely outpace their ocean cousins.

Which makes sense. Water may seem flat, until you start blowing on it, then it gets really hilly, not to the mention phase change effects of water that alter the composition and energy of the air that blows over it.

cran
2009-Jan-09, 01:04 PM
You'll note I said "similar", not "identical"; the authors list the points of similarity in my quotation. And I referred specifically to the absence of continuously roaring zonal storm winds when I suggested BigDon's question had been answered.

I'm sorry if you think I've misled BigDon with anything I've said. But having given the links to relevant papers, I believe I can probably bow out now and let him make up his own mind with your guidance.

Grant Hutchison
apologies for the delay - the dreaded "real life" intervened*

interestingly, the Southern Ocean makes a strong case for persistent zonal winds ... but I think you already pointed that out ...

the persistence (longevity) of any given eddy/storm cell in the westerly mid lats, or easterly tropics, is purely down to the probability of cell mergers, and eddy tracks ... the number of eddy/cell generations per year might not be much different, but track lengths on average could be significantly longer ... compare the evolution of Atlantic hurricanes with Pacific cyclones or typhoons ...

it's already been noted that the ENSO cycle doesn't appear; neither does the annual monsoon fluctuation ... with both annual and decadal reversals removed, the persistence of the tropical easterlies seems more likely ...

without western boundary currents, thermal exchange seems dependent upon Ekman transport and eddy generation ... there were mentions of overturning and upwelling, but without basin topography, I'm not sure how this would work beyond the polar regions ...

you might note that I've made no reference to faster winds, merely to simplified and more persistent winds or wind patterns ... and from that, a more visible adherence to the zonal diagram (with some of those ocean-borne storms/circular cloud patterns viewed from space thrown in) ...


*if you can possibly avoid it, don't become an invalid ...