Guest Post by Willis Eschenbach
I got to thinking about the idea of a temperature field. By that I mean nothing more than an estimation of theoretical temperatures given some variables like say latitude and elevation. We all know that as we go poleward it gets colder, and the same is true when we go upwards into the mountains. So we can make a formula that can estimate the temperature at any spot on the Earth if we know its latitude and elevation. It’s an excellent estimation, with an R^2 of 0.94.
In the CERES satellite data, the relationship works out like this. Start at minus thirty-one degrees. Add sixty times the cosine of the latitude. Then subtract six degrees for every thousand metres of elevation. That gives you the estimated temperature for any given location. I note that the decrease in temperature at higher altitudes, about six degrees C per thousand metres of elevation, agrees well with the generally estimated figure for the “environmental lapse rate”, which is the average rate at which the atmosphere cools with increasing elevation.
However, of course in the real world temperatures are never that simple. But what is of interest is not the estimated temperature of the temperature field. It is the real world observed temperature minus the estimated temperature. This shows us the locations where reality departs from the model, which is always the informative part of any model. Figure 1 shows two views of the observations minus estimation results, one centered on the Atlantic and one on the Pacific.
Figure 1. Atlantic- and Pacific-centered views of the observed temperatures minus the estimated temperatures based solely on latitude and elevation.
I certainly did not expect the planetary hot-spot, where it is the warmest compared to the temperature field, to be up north of the horizontal dotted line marking the Arctic Circle. (Note that this has nothing to do with whether the globe is warming or cooling. It’s just average temperature observations minus an estimate based solely on latitude and elevation.)
Looking at these figures, I finally understood the difference between temperatures in the Atlantic and the Pacific. It has to do with the different shapes of the western shorelines of those oceans.
In the Pacific (lower figure), you can see the effect of the El Nino/La Nina pumping action. As I detailed in The Tao of El Nino, http://wattsupwiththat.com/2013/01/28/the-tao-of-el-nino/ the action of the combined Nino/Nina periodically pumps warm surface water westward across the Pacific. When it hits the cup-shaped shoreline of Australasia, the warm water splits into two parts, one moving to the north and one south. This results in the two lobes of warmer-than-estimated water in the northward and southward branches of the Pacific poleward ocean heat transport. It is also responsible for the warm spot in the Gulf of Alaska, and the anomalous warmth of the entire west coast of North America.
In the Atlantic (upper figure), on the other hand, the western shoreline is not cup-shaped as in the Pacific. Instead, well below the Equator the nose of South America sticks out to the east. The ocean naturally flows westward around the Equator, driven by the trade winds (shown below). South America unevenly splits this western flow of warm surface water, with most of it moving northwards as the Gulf Stream, and only a small amount moving southwards. The Gulf Stream in turn has no place to disperse as exists in the Pacific, because the Atlantic is wedge-shaped and the heat is trapped in the upper corner. This uneven split leads to the red-colored hotspot in the North Atlantic, as well as the corresponding cool spot in the South Atlantic/Southern Ocean.
In both the north Atlantic and north Pacific, this has lead to excess warmth on the western shores of the continents (Europe and Alaska/Canada/NW USA). And this in turn seems related to the excess cold on the eastern shores of the continents, although the mechanism is obscure. And this cool air on the eastern shores of the continents seems to spill out over the ocean, leaving it cooler offshore than we’d expect.
These figures also highlight the difference between the Antarctic, which is mostly kilometre-thick ice underlain by solid rock and cold to the bone, and the Arctic, which is mostly a few metres of ice underlain by warmer liquid water.
Next, I learned that looking at observations minus the temperature field highlights the great desert belts at about thirty degrees north and south of the Equator. I’ve been thinking about these lately. The deserts form as a result of the tropical evaporation and the resulting deep tropical convection that drives the “Hadley cells” on each side of the Equator.
Figure 2. Global atmospheric circulation showing surface winds and the atmospheric cells.
Warm moist air moves aloft in the deep tropics. The water is stripped out by condensation and high-altitude freezing and returned to the surface. The air aloft moves polewards north and south, and descends at around 30° N/S, warming as it loses altitude. This descending dry air doesn’t contain enough moisture to form clouds, which in turn leads to a dry, hot surface.
To see this more clearly here is a look at the land-only temperature-estimates data with the ocean clutter removed:
Figure 3. As in Figure 1, but with the ocean data removed.
The horizontal dotted lines mark the furthest north and south that the sun is directly overhead at least one day a year. These are the tropics of Cancer and Capricorn, in the old terminology (23.5° North & South). You can see that the warm descending air from the Hadley cells makes those two areas warmer than is estimated from just their location and elevation.
Anyhow, that’s what I see in the variations from the temperature field. As always, YMMV.
Best to all,
w.
My Usual Request: If you disagree with me or anyone, please quote the exact words you disagree with. I can defend my own words. I cannot defend someone’s interpretation of my words.
My Other Request: If you think that e.g. I’m using the wrong method on the wrong dataset, please educate me and others by demonstrating the proper use of the right method on the right dataset. Simply claiming I’m wrong doesn’t advance the discussion.
Willis
For what its worth I live at sea level. I frequently travel to our nearest upland area-Dartmoor-where there is a notable 1000 and 1500 foot contour.
Consequently, when I set off I invariably make an estimate of the expected temperatures of the above heights.
Around 25% of the time the estimate is pretty close. Around 25% of the time the estimate is notably too warm and 25% of the time notably too cold. The other 25% represents where there has been a temperature inversion.
This all varies somewhat winter to summer but within those categories. Whether that all ‘averages’ out to match the official ‘estimated’ temperatures I don’t know.
tonyb
Tony, I did a small sample study to show that this type of generality (a Statement by S Mosher saying the same thing) does not work for coastal areas.
Just compare the UK with Canada at the same latitude and sea level, you can get temperature differences of 10 degrees C at any time.
You also have a Major East to West difference for most coast as well, just look at temps on either side of any Continent to see what I mean. This is especially obvious for Australia.
I think the flow of water over the Pacific is more a result of Ekman pumping/transport. To say that the warm water is pushed west and then splits either side of Australia is way too simple IMO. The combination of trade wind friction on the surface induces an Ekman flow at right angles to the right in the N Hemisphere and to the left in the S Hemisphere. Sure right on the equator this is not true but the trade winds extend far enough either side to induce Ekman flow. This continues and is reinforced by the semi permanent location of the S and N Pacific Anticyclonic Gyres. So the predominant wind in the E Pacific has a more N (N hemisphere) S (S Hemisphere) whilst the western side of the Pacific there is an opposite wind bias on the western side of both subtropical anticyclones. The net result is the cool water is pooled over the eastern boundary currents e.g. Humbolt and California currents. Meanwhile warm water is pooled N and S of the ITCZ and equator where it is also enhanced by calm mostly sunny anticyclonic weather within the subtropical highs.
Here is a link showing the flow.
http://www.thisisyourbrainonawesome.com/2012/07/why-is-californias-coast-so-cold-anyway/
and also here
http://www-das.uwyo.edu/~geerts/cwx/notes/chap11/equat_upwel.html
So the idea that land mass shape determines where the equatorial warm water flow goes is in my opinion not quite correct. It is however, correct that the land mass shape or location does alter wind flow directions which in turn can alter sea current direction. It may be pedantic but the idea of warm surface water just being pushed across the Pacific is way to simplified.
Hats off to you WIllis! Someone actually testing a model (no matter how basic) to real-world measured average temperatures and seeing where there model does well and where it doesn’t do so well. We never really get that from the alarmist.
Actually that is exactly what we do in Berkeley earth.
Question: see Willis’s other post on Ceres.. do you see whose name he mentions?
excess cold on the eastern shores of the continents, although the mechanism is obscure
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prevailing winds. the eastern shore is not cold in southern hemisphere, or in lower latitudes.
“(Note that this has nothing to do with whether the globe is warming or cooling. It’s just average temperature observations minus an estimate based solely on latitude and elevation.)”
Willis, the interesting northern Atlantic hot spot might be influenced by rising temperatures. A possible mechanism could be the following:
Warming: ITCZ (thunderstorms) dries the air. In the Caribbean the (dryer) trade winds enhance evaporation, moisture which doesn’t rain down at that latitude. The resulting saltier water is transported by the Gulf Stream northwards and, because the water is being more heavy than before, there is a bigger ‘sink’ in the pole region. The bigger sink enhances the Gulf Stream and so the Hot Spot is getting hotter.
So, the Atlantic Ocean could have its own Heat Pump that reacts on global temperature rise. The Pump works both horizontally and vertically. And the vertically part works both upwards and downwards: a sink of warmer sea water (possible because it is saltier and the surroundings are warmer too) and by an extra upward transport of energy. For the last thing, I would like to know your ideas about the following.
In your thunderstorm posts, you already showed the reaction by the tropics on warming. At the higher latitudes rising temperature differences (when land surfaces are warming and ocean surfaces are lagging behind) can create pressure differences which result in stronger depressions and stronger [surface] winds in the temperate cell region. Stronger depressions can transport more (huge) masses of relatively warm air upwards – in the direction of the upper layers of the atmosphere where this heat can be emitted. So, this mechanism could be a second ‘cooling pump’ and as a side effect, it can help to create more pronounced northern hot spots. Because of this stronger depressions the cold southward streams on the western part of the oceans will be enhanced, while in the eastern part of the oceans the warm northward streams are enhanced. A nice view of those depressions: http://earth.nullschool.net/#current/wind/surface/level/orthographic=182.85,82.48,486
It will be interesting to hear your ideas about this.
Best wishes,
Wim Röst
P.S. Great post!
P.S.2 Cold upwelling water on the east side of the oceans helps to create relative high pressure areas which influences the nearby land. Lowering air up there will result in dry sunny and warm deserts.
‘In the CERES satellite data, the relationship works out like this. Start at minus thirty-one degrees. Add sixty times the cosine of the latitude. Then subtract six degrees for every thousand metres of elevation. That gives you the estimated temperature for any given location.’
It seems to me that the data just disproves that the formula.
No single location has data that exactly matches the formula but over the globe as a whole all data does average out to the formula, hence the Standard Atmosphere is so accurate that it can be used for aeronautics and rocketry.
Thanks!
Do you know if the ‘minus thirty-one degrees,’ ‘sixty times the cosine,’ and ‘subtract six degrees’ were derived from known phenomena, or are they kluges that just happen to work?
Gamecock January 21, 2016 at 4:11 am
Good question, Gamecock. They are fitted using multiple linear regression.
w.
To me this shows quite clearly the effects of prevailing winds and oceans warmth warming the land. all areas that aren’t blocked by some form of mountain range are warmer from western coastal areas slowly cooling as you move east..
Yes, where the air is dry it is hotter. Add a humidity factor over land. Dry descending air lets more sun be absorbed at ground level instead of in clouds.
Also look at the Southern Ocean and how that sends a cold current up the west side of South America when it whacks into Drake’s Passage.
https://chiefio.wordpress.com/2010/12/22/drakes-passage/
Cold flow from the Southern gyres explains the cold ocean spots in the S.H. Add a factor for ocean gyres desplacing water by latitude.
Nice visualization BTW.
From somewhere long ago: “Models inform our ignorance”.
Roughly the same as your point about informing when compared to reality.
“Dry descending air lets more sun be absorbed at ground level instead of in clouds.”
And also instead of in water vapour, it absorbs fair amounts of solar near infrared.
Nick Stokes interesting video. Do you know of a model without the Panama dam? Would be interesting.
Yes, it would. But sorry, I don’t know of such.
Willis,
Very fine pondering and reasoning I feel, thank you.
“So we can make a formula that can estimate the temperature at any spot on the Earth if we know its latitude and elevation. It’s an excellent estimation…”
Perhaps that could be displayed visually as well . . for pondering purposes ; )
That is a fundamental characteristic of the Standard Atmosphere already in constant use for aeronautics and rocketry.
Stephen ,
So . . are you suggesting I go find it somewhere else?
John, I could display it but it is very boring, as it is very similar to the actual temperature field, cold at the poles and in the mountains—which is why I’ve displayed the difference between the field and the observations.
All the best,
w.
Willis,
“…it is very similar to the actual temperature field, cold at the poles and in the mountains…”
I get that, but it’s obviously not the same . . and no, I’m not in the market for a pondering coach, but thanks anyway . .
This is NOT a map of warming in any way, shape, or form, global or otherwise.
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Willis, it might be a map of natural warming. it shows that the Arctic is much warmer than is predicted by its location and elevation.
The forces of Nature that caused this might have turned off during the LIA for example. If for example we looked at the same map of the earth from 1500, would be see the same warm spot?
The Arctic warm spot might be the cause of the Modern Warming, or at least a marker for the natural changes to the ocean circulation that are causing temps to rise for the past couple of hundred years.
During the LIA one would see a colder Arctic than at present due to increased global cloudiness (solar induced in my view) having reduced the proportion of solar energy getting into the oceans.
The overall pattern of warm and cold spots ould be much the same, however.
What about the ships logs that reported considerable loss of Arctic sea ice 1816-1818?
This is really cool. It is amazing how well the simple model matches observations. Next step would be to calculate the differences on a year-by-year -basis and see if therein lies a hint for the warming or the pause.
Correct as far as it goes but one must take it to the logical conclusion as I have suggested to Willis on previous occasions.
That ‘temperature field’ is set by mass, gravity and insolation working together via conduction and convection, NOT internal radiative fluxes.
All internal radiative fluxes are merely a by product of thermal irregularities within the system caused by variable energy flows through the various materials of ground, ocean and atmosphere.
Over time, the energy value of irregularities above and below the value determined by mass, gravity and insolation must net out to zero if an atmosphere is to be retained.
That stability is achieved by variations in the lapse rate slopes from one place to another rather than by changes in average surface temperature.
For every region that has a higher surface temperature than that set by gravity, mass and insolation there is a region with a correspondingly lower surface temperature.
All radiative imbalances within the system are returned to neutrality by convective adjustments in order to maintain the hydrostatic balance of the mass of the atmosphere against gravity for the long term.
One regional manifestation of the convective adjustment process is the maximum achievable water surface temperature in equatorial regions as noted by Willis in his Thunderstorm Hypothesis. That maximum achievable water surface temperature is set by the pressure of air bearing down on the water surface because that pressure determines the energy cost of evaporation via the latent heat of vaporisation which at 1 bar atmospheric pressure is a ratio of about 5 to 1.
Note that in the CERES diagrams the positive (warm) values are generally where there is descending air in higher pressure cells and the negative (cool) values are generally where there is rising air in lower pressure cells.
Naturally, rising air must be equal to descending air for convection within an atmosphere held in hydrostatic balance against gravity so it follows that the warm areas must equal the cold areas for a net zero effect on radiative emissions to space.
Since the Arctic shows up as warmer than the tropics whereas in fact the surface is much colder it must follow that we are not looking at surface warmth but rather warmth within the vertical column above the relevant region.
Thus, what CERES shows us is adiabatic warming of descending air within regions of higher pressure and adiabatic cooling of ascending air within regions of lower pressure.
CERES is showing the real world distortions of the lapse rate slopes within ascending and descending columns away from the formula dictated by the temperature field which is in turn set by mass, insolation and gravity.
All those distortions must net out to zero if an atmosphere is to be retained.
Radiative fluxes within the system are then a consequence of those adiabatic processes and NOT causes of anything.
When the r.m.s. discrepancy between the empirically fitted model projections for average temperature and measured reality is a few degrees and the extreme absolute discrepancies top 10K, the projections can hardly be called “excellent” in any practical sense. The high overall R^2 between the two is more the result of the wide range (~50K) of absolute average temperatures found on the globe, than of closeness of fit to the actual spatial temperature field.
This exposes the fundamental foolishness of BEST’s usage of such model projections to determine not only the reference levels for all station data, but for filling in (kriging) many regions where no station data is at hand. Their methodology is totally unacceptable as a substitute for having complete geographic coverage.
It should also be noted that the 14 years of CERES data utilized here is simply too short a record to reveal very closely the stable patterns of field variability in the presence of strong multidecadal oscillations, which are by no means uniform around the globe. Clearly the phase of these oscillations exerts a distinct modulating effect upon 14-year averages, which requires much longer records to be suppressed. This sort of uneven modulation is the reason why long series of average temperatures cannot be reasonably reconstructed without recourse to long data records. BEST’s resort to indiscriminate “scalpeling” of long records into mere decadal-length segments is a move completely in the wrong direction; reconstructions obtained by stitching together such segments tend to strongly suppress multidecadal and longer climate signal components.
1sky1 January 21, 2016 at 12:28 pm
I do wish folks would actually do the work before uncapping their electronic pens to declaim passionately about something they’ve never tried … in fact, 1sky1, I did the same analysis using the HadCRUT4 data and found little difference from the results shown in Figure 1—warmer at 30° N/S, hottest in the North Atlantic above the Arctic Circle, same signs of El Nino circulation in the Pacific. If you got something different, please present your graphic.
w.
I do wish that folks would learn to read closely such phrases as “reveal very closely” and stop reflexively imputing passion and/or inexperience upon their critics. I especially wish this upon someone who has no clue that HADCRUT4 very much reduces the multidecadal oscillations in question in order to emphasize a highly dubious global trend.
It’ll be interesting to see how much certain regions will change in the next cold AMO mode.
“Looking at these figures, I finally understood the difference between temperatures in the Atlantic and the Pacific. It has to do with the different shapes of the western shorelines of those oceans.”
Funny, I thought it was more to do with the opposing thermohaline circulation patterns:
http://astronomy.ua.edu/white/xtra/thermohaline_circulation.jpg
ulric, you are right … but what I finally understood was why the same winds blowing westwards across the Pacific don’t lead to the same currents.
In addition, that chart is no longer thought to be an accurate map of the currents—they turn out to be much more complex than we thought. See “Deconstructing the Conveyor Belt” in Science mag, along with a discussion of the paper here.
w.
The Stommel flow field for the Pacific is a short circuit, cold and warm flows are in the same direction, that is irrational. And Lozier only deconstructs the Atlantic, so we are none the wiser about the Pacific flow field from that: http://www.whoi.edu/cms/files/lozier10sci_95064.pdf
I agree with Broecker about changes in overturning being intrinsic to glacial periods, probably ice shelves effecting the Achilles heel of the North Atlantic, but that’s another topic.
The surface climate is affected primarily by wind-driven surface currents, rather than by the weak-sister adjunct of gravity-driven THC. It’s high time to recognize that fundamental geophysical fact.
Willis Eschenbach
January 19, 2016 at 8:59 pm
“Good question, Bob. The values are the result of simple linear regression of the form:
Temperature = X times cos(Latitude) + Y times Elevation + Z
When solved using the 14-year CERES dataset, I get
X= 60° times cos(latitude)
Y= 6°C/1000 metres,
Z= -31°C”
I have repeated your simple linear regression with the HADCRUT4 2014 data. For the elevation of a 5°x5° grid element, I used the mean elevation of the weather stations inside this element. I found
Z= -31 °C, X= 59 °C, and Y= -4 °C/km. The standard deviation of the residual was SDR= 4°C and R^2= 0,92. For Ceres 2014, I found Z= -31 °C, X= 60 °C, and Y= -4 °C/km, SDR= 4°C and R^2= 0,92. So, the results are essentially the same as yours. Only the lapse rate Y is lower. But the fit is not very sensitive to Y.
I have done a similar linear regression analysis of the 2014 RSS satellite data: Ta= Z+X times cos(Latitude).
TLT: Z= -41°C, X= 47°C, SDR= 3°C, R^2= 0,90.
TMT: Z= -49°C, X= 34°C, SDR= 2°C, R^2= 0,91
TTS: Z= -53°C, X= 7°C, SDR= 1,4°C, R^2= 0,60.
TLS: the fitting function is not useful.
So X is decreasing with increasing elevation. I think that the meridonial heat transport increases with elevation.
Interesting: the hot spot in between Norway and Svalbard in the first figure is exactly the opposite of the situation 20.000 years ago. See the illustration: http://wattsupwiththat.com/2016/02/02/glacial-erosion-co2-and-volcanoes-the-chicken-and-the-egg-problem/comment-page-1/, comment vukcevic, February 2, 2016 at 8:49 am.
Comparing the two illustrations suggests that a complete other kind of pressure – wind – ocean currents – temperature systems must have existed, 20.000 years ago. Land ice was centered around the North Atlantic. Indeed, where we find the present hot spot.