Stratosphere Temperature Watch 2012/2013

[Ice BIast]

Is it true (amazing to me if it is) that Mountain Torque effects (low pressure one side of a range, high on the other) actually slows the earths spin (albeit miniscule amounts)?

I'm genuinely impressed by that as a backyard astronomer.

Des.

I believe so, it surprised me too though! Although if I remember correctly, this applies to -ve mountain torque events, and +ve events speed up the earths rotation. Someone correct me if im wrong.

[Relativistic]

Just found this Skyraker, Chiono posted this a while back from a paper:

Mountain Torque is a function of pressure and orography and is the ‘turning force’ exerted

due to a difference in pressure across any raised surface on the earth, but most signiï¬cantly,

mountains or mountain massifs. Consider a mountain with a high pressure on the west side

of a mountain and low pressure on the east. The pressure system will exert an eastward

torque that causes the earth to increase it’s rate of rotation, imparting angular momentum

from the atmosphere to the solid earth. The opposite case, where there is higher pressure

on the east side of the mountain, will slow the earth’s rotation down, reducing the solid

earth’s angular momentum, and imparting it to the atmosphere.

Here is the paper:

http://www.reading.ac.uk/web/FILES/maths/Simon_Driscoll.pdf

Edited November 12, 2012 by 22nov10blast

[Alan Robinson]

Just found this Skyraker, Chiono posted this a while back from a paper:

Mountain Torque is a function of pressure and orography and is the ‘turning force’ exerted

due to a difference in pressure across any raised surface on the earth, but most signiï¬cantly,

mountains or mountain massifs. Consider a mountain with a high pressure on the west side

of a mountain and low pressure on the east. The pressure system will exert an eastward

torque that causes the earth to increase it’s rate of rotation, imparting angular momentum

from the atmosphere to the solid earth. The opposite case, where there is higher pressure

on the east side of the mountain, will slow the earth’s rotation down, reducing the solid

earth’s angular momentum, and imparting it to the atmosphere.

Here is the paper:

http://www.reading.a...on_Driscoll.pdf

That proposition seems to me most improbable. Considering the mass of the air in the high pressure system, the mass of Earth, and Newton's second law, I should have thought we could see "highs" bouncing off mountain ranges, but they don't seem to me affected by, say, the Ural Mountains, and neither have I observed that that the huge Asian winter high north of the Himalayas causes Earth to start rotating north - south in winter. Of course there is a reaction from Earth, but what form it takes is most complex, and in any case it is so insignificant we have always ignored it. If this is supposed to be accepted science, it ought to be possible to measure it going on.

When I think of Earth's surface, with the Andes, Rocky Mountains, Ghats, Atlas mountains etc each experiencing weather, and when I think of tectonic plates floating about like seperate islands, the plastic nature of Earth's crust and the molten core, the idea that high pressure pressing against a mountain range alters Earth's rate of rotation seems impossible to prove, for which reason I am inclined to dismiss the notion as metaphysics.

Wouldn't stong winds crossing a mountainous coast have the same effect if this is true? isn't it likely that high winds and high pressure to one side of mountain ranges would cause earthquakes? How can we compile excellent astronomical almanacs if Earth's rate of rotation is subject to the whim of weather? Does Earth's rate of rotation change when a storm surge presses masses of the Southern Ocean against the continental shelf off Chile?

Edited November 13, 2012 by Alan Robinson

[FrenchScotPilot1]

Looks like the latest run of ECMWF for 240 h is showing wave 2 backing down a bit from yesterday.

E.g. geopotential is only 500 where is was forecast to be 650 yesterday (http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/eczm.php?alert=1&forecast=f240&var=ha2&lng=eng)

[Relativistic]

That proposition seems to me most improbable. Considering the mass of the air in the high pressure system, the mass of Earth, and Newton's second law, I should have thought we could see "highs" bouncing off mountain ranges, but they don't seem to me affected by, say, the Ural Mountains, and neither have I observed that that the huge Asian winter high north of the Himalayas causes Earth to start rotating north - south in winter. Of course there is a reaction from Earth, but what form it takes is most complex, and in any case it is so insignificant we have always ignored it. If this is supposed to be accepted science, it ought to be possible to measure it going on.

When I think of Earth's surface, with the Andes, Rocky Mountains, Ghats, Atlas mountains etc each experiencing weather, and when I think of tectonic plates floating about like seperate islands, the plastic nature of Earth's crust and the molten core, the idea that high pressure pressing against a mountain range alters Earth's rate of rotation seems impossible to prove, for which reason I am inclined to dismiss the notion as metaphysics.

Wouldn't stong winds crossing a mountainous coast have the same effect if this is true? isn't it likely that high winds and high pressure to one side of mountain ranges would cause earthquakes? How can we compile excellent astronomical almanacs if Earth's rate of rotation is subject to the whim of weather? Does Earth's rate of rotation change when a storm surge presses masses of the Southern Ocean against the continental shelf off Chile?

That's just what I know. Earth's atmospheric angular momentum varies all the time and that momentum has to go somewhere, through events such as mountain torques.

I think what you described with wind over mountains is called frictional torque, someone correct me if I'm wrong.

[chionomaniac]

That proposition seems to me most improbable. Considering the mass of the air in the high pressure system, the mass of Earth, and Newton's second law, I should have thought we could see "highs" bouncing off mountain ranges, but they don't seem to me affected by, say, the Ural Mountains, and neither have I observed that that the huge Asian winter high north of the Himalayas causes Earth to start rotating north - south in winter. Of course there is a reaction from Earth, but what form it takes is most complex, and in any case it is so insignificant we have always ignored it. If this is supposed to be accepted science, it ought to be possible to measure it going on.

When I think of Earth's surface, with the Andes, Rocky Mountains, Ghats, Atlas mountains etc each experiencing weather, and when I think of tectonic plates floating about like seperate islands, the plastic nature of Earth's crust and the molten core, the idea that high pressure pressing against a mountain range alters Earth's rate of rotation seems impossible to prove, for which reason I am inclined to dismiss the notion as metaphysics.

Wouldn't stong winds crossing a mountainous coast have the same effect if this is true? isn't it likely that high winds and high pressure to one side of mountain ranges would cause earthquakes? How can we compile excellent astronomical almanacs if Earth's rate of rotation is subject to the whim of weather? Does Earth's rate of rotation change when a storm surge presses masses of the Southern Ocean against the continental shelf off Chile?

Alan the answers are yes - that all does occur - but the effect on the earths rotation is negligable - however it isn't negligable on the reverse- the global wind oscillation (GWO)

Edited November 13, 2012 by chionomaniac

[chionomaniac]

Looks like the latest run of ECMWF for 240 h is showing wave 2 backing down a bit from yesterday.

E.g. geopotential is only 500 where is was forecast to be 650 yesterday (http://wekuw.met.fu-...var=ha2&lng=eng)

Yes I agree, with that FSP - I suspect that we will need further wave activity further down the line.

One thing I noticed this morning is the slightest hint of an upper warming (1hPA) about to occur? Who knows?

[syed2878]

hi chio a qs. With the data we have available to us what is the lowest strat temp recorded and and highest recorded? Thx.

[Alan Robinson]

That's just what I know. Earth's atmospheric angular momentum varies all the time and that momentum has to go somewhere, through events such as mountain torques.

I think what you described with wind over mountains is called frictional torque, someone correct me if I'm wrong.

Yes there is friction because there is contact and movement. But think of the roof on your house, the timber structure is there to prevent the wind pressure distorting the roof. Pressure is force * area. It is exactly the same with mountains, and the wind causes pressure on the slopes. That pressure is resisted by stresses in the ground, which is why I mentioned earthquakes. If the wind force was sufficient to alter Earth's rotational velocity, I am convinced there would be earthquakes.

We have also to consider that strong winds probably exert a greater force on mountains than mere barometric pressure. The Trade Winds and monsoons most generally affect low-lying coastlines, while the westerlies hit the Andes and the Rockies. If the westerlies cause Earth's rotational velocity to increase, where then are the winds that slow it down again? Newton's First Law states earth will continue rotating at a constant velocity unless something happens to slow it down. Something has to counteract the westerlies hitting the Andes and Rockies. What exactly?

Moreover, as I put, people are able to calculate the positions of stars, planets, moon and sun in the sky with such considerable accuracy many years in advance, that we are able to navigate the oceans using a sextant and chronometer; and navigators have never in my knowledge reported in recent times that the almanac has been wrong, which it would be if Earth was speeding up and slowing down because there happens to be a big high off Chile.

I'd say that the kind of observations navigators carried out before GPS arrived amount to a huge scientific experiment. The calculations on which the almanac is based are the theory, and the theory is confirmed by practical observations that can be repeated by anyone, anywhere if they are taught and equipped. This means that scientifically speaking, Earth's rotational velocity is not subject to any significant random variation (highs off Chile or British Columbia), and that the variations that do occur are predictable. It follows that the notion of high pressure next to mountains altering Earth's rotational velocity is most unlikely.

Edited November 13, 2012 by Alan Robinson

[Typhoon John]

I don't think there is any suggestion that the earth itself slows or speeds up, the effect is so small as to make no difference.

However, when negative mountain torques occur the momentum is transferred to the atmosphere in the form of waves through the atmosphere that can have a measurable effect on the atmospheric circulation.

When these waves reach the stratosphere they can cause warming and reverse the polar flow. That is what is measurable and what we're looking for evidence of in this thread.

[chionomaniac]

I think that if anyone wishes to discuss the transfer of energy from the atmosphere to the earth that it is now done in a new topic so that we can keep this one relevent, interesting though that the discussion is.

Thanks.

[chionomaniac]

Back to the stratosphere. The latest forecasts are veering away from a lower strat split today. The increased wave activity is causing distortion of the stratospheric vortex - my thoughts are very much along the lines that this wave 2 activity will not be enough in itself to lead to prolonged blocking but will set off a number of trop/ strat feedback waves that eventually will lead to a warmer strat.

I think that it is very unlikely that we will see a Canadian Warming this month.

[chionomaniac]

hi chio a qs. With the data we have available to us what is the lowest strat temp recorded and and highest recorded? Thx.

That depends on what pressure level, latitude and time of year that you mean.

Data here to check http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/ - if you have difficulty viewing due to a VI, syed I will look later for you.

[syed2878]

thanks chio. Im talking during nh winter.

[Alan Robinson]

I don't think there is any suggestion that the earth itself slows or speeds up, the effect is so small as to make no difference.

I agree the effect - if there is one - is insignificant, however see #602 where it certainly is suggested Earth's rotation velocity is affected, which is why I saw fit to comment.

[chionomaniac]

I agree the effect - if there is one - is insignificant, however see #602 where it certainly is suggested Earth's rotation velocity is affected, which is why I saw fit to comment.

The way it is worded to the uninitiated, one would imagine that the earth's spin could almost grind to a halt if the MT is strong enough! - however in practical terms we know that the effect is negligable!

[CanadaAl]

Hey guys, I'm new to this Strat thread and I was just wondering if someone would be able to explain what MB is in terms of the strat, is it millibars like pressure? Also, which start catergory should i be looking at on this page: http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/?

Thanks a lot for the help

[chionomaniac]

Hey guys, I'm new to this Strat thread and I was just wondering if someone would be able to explain what MB is in terms of the strat, is it millibars like pressure? Also, which start catergory should i be looking at on this page: http://www.cpc.ncep....e/temperature/?

Thanks a lot for the help

You're right it is millibars in that context - effectively the same as hPa for the level that we look at.

[Relativistic]

Yes there is friction because there is contact and movement. But think of the roof on your house, the timber structure is there to prevent the wind pressure distorting the roof. Pressure is force * area. It is exactly the same with mountains, and the wind causes pressure on the slopes. That pressure is resisted by stresses in the ground, which is why I mentioned earthquakes. If the wind force was sufficient to alter Earth's rotational velocity, I am convinced there would be earthquakes.

We have also to consider that strong winds probably exert a greater force on mountains than mere barometric pressure. The Trade Winds and monsoons most generally affect low-lying coastlines, while the westerlies hit the Andes and the Rockies. If the westerlies cause Earth's rotational velocity to increase, where then are the winds that slow it down again? Newton's First Law states earth will continue rotating at a constant velocity unless something happens to slow it down. Something has to counteract the westerlies hitting the Andes and Rockies. What exactly?

Moreover, as I put, people are able to calculate the positions of stars, planets, moon and sun in the sky with such considerable accuracy many years in advance, that we are able to navigate the oceans using a sextant and chronometer; and navigators have never in my knowledge reported in recent times that the almanac has been wrong, which it would be if Earth was speeding up and slowing down because there happens to be a big high off Chile.

I'd say that the kind of observations navigators carried out before GPS arrived amount to a huge scientific experiment. The calculations on which the almanac is based are the theory, and the theory is confirmed by practical observations that can be repeated by anyone, anywhere if they are taught and equipped. This means that scientifically speaking, Earth's rotational velocity is not subject to any significant random variation (highs off Chile or British Columbia), and that the variations that do occur are predictable. It follows that the notion of high pressure next to mountains altering Earth's rotational velocity is most unlikely.

The effect is there, but it is tiny, which I think is what you are trying to get at. I never suggested that the effect was measurable, which is where I think the confusion has arisen!

Pressure is Force/ Area by the way.

I think that if anyone wishes to discuss the transfer of energy from the atmosphere to the earth that it is now done in a new topic so that we can keep this one relevent, interesting though that the discussion is.

Thanks.

Yes, either that or we draw a line under it.

Edited November 13, 2012 by 22nov10blast

[MattH]

With signs of the -80c isotherm appearing on the ECM charts out to day 10 near the 20hPa/30hPa mark, I can't help but wonder whether it is just a matter of time before the intense cold associated with the stratospheric vortex filters down and influences the troposphere;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_t_f240.gif

The wave 2 activity is still there and peaks now near day 7, but clearly the trend from a few days ago is for the intensity of this wave to be somewhat less than was original expected. Clearly Ed suggested 750(m') was of worth, it's falling at least 200m short of that right now...

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwfzm_ha2_f168.gif

There are still signs of the main vortex at 30hPa becoming more elongated with time and again the ECM out to day 10 continues that trend from previous days;

http://wekuw.met.fu-berlin.de/~Aktuell/strat-www/wdiag/figs/ecmwf1/ecmwf30f240.gif

As we have seen for the majority of this autumn despite quite potent conditions within the stratosphere the conditions within the troposphere have been far from responsive and as a result we have yet to experience a proper spell of zonal conditions with a major +AO and +NAO pattern sustained for a week or two. The persistence of the EC 32 Day in terms of developing northern blocking is impressive and my experience with this model is that it is more right than wrong and if this general pattern of higher pressure to the NE, N or NW of the UK in some shape or form develops by late November then hat's off to it. However, the continued conditions 'higher up' continue to leave me with a niggling concern in my side that it's going to take time before we see any persistent HLB's becoming established in the coming weeks.

Using a rather random analogy, but my thinking is sort of like that game you see at funfairs where there are 10 tin cans stood in a tower and you're given 3 balls to try and knock them all over. This current wave 2 activity is sort of your first ball, but clearly with that you may only knock one or two of the tins over. It may well take the 2nd or even 3rd ball to properly dismantle that tower and to me, I believe, that is what is required in the coming weeks/month. If we don't see an increase in wave activity and some gradual warming then I can't help but think that overall December will be lacking any significant HLB and thus a risk of proper sustained cold weather.

As we have found out in the past and last year being a perfect example, patience is a virtue when it comes to the stratosphere but I just hope, from a cold lovers point of view, that we don't have to wait until the end of January or early February to get a real risk of something of worth. Clearly there have and continue to be some well documented "variables" that point towards a colder than average winter, I just hope that the stratosphere is peaking early and will be 'knocked off its perch' within the next month or so, as it's going to take some major 'events' to reverse the conditions which are currently present at and above 30hPa in particular

Regards to all, Matt.

[chionomaniac]

Just quickly, Matt, as I am at work, but I agree with all of that and was going to post something similar today, so thanks for saving my slow typing fingers!

[bluearmy]

. Stewart seems to expect plenty wave 2 activity over the next few weeks. My understanding being that the activity we see now forecast is the consequence of trop waves a few weeks ago and the trop picture over the past couple weeks/currently will lead to more of this.

whilst I would tend to agree with you, I've rarely seen GP so bullish about the next month or so.

The current wave 2 forecast seems to prevent the zonal wind going above 30 m/s at 30 hpa.

Edited November 14, 2012 by bluearmy

[FrenchScotPilot1]

Thanks for a professional sum up Matt.

I guess most people follow the evolution on the Berlin site but is there a possibility to access the EC 32 Day or is it only available to professionals?

Thanks,

Stephane

Edited November 14, 2012 by FrenchScotPilot1

[MattH]

Thanks for a professional sum up Matt.

I guess most people follow the evolution on the Berlin site but is there a possibility to access the EC 32 Day or is it only available to professionals?

Thanks,

Stephane

Unfortunately not I'm afraid, it's only available to companies who have paid the ECMWF for it, these usually being WMO organisations. Obviously I can offer text updates and information and clearly the 15 to 30 day outlook on the UKMO website is based on the EC 32 day primarily, but as for graphics and info, that's not online to the public.

Cheers, Matt.

[lorenzo]

If I am going to a fun fair today, its going to be the MJO one in Kamchutka, think the balls (ridges) used there might help win the game.

Saying that some less positive signals defined by HM over on US Wx, solar activity cited as cranking the vortex up.

Finely balanced..