Major flaw found in Arctic temperature reanalysis – exaggerates warming

This might put a kink in the RC posited “polar amplification of temperature” that is expected from AGW. A previous paper published in Nature (Screen & Simmonds 2010) said:

The ERA-40 reanalysis has been used to show that Arctic warming trends aloft were of equal or greater magnitude than those at the surface, leading to the conclusion that atmospheric circulation changes were a more important cause of recent Arctic amplification than retreating snow and sea ice cover.

But even then they started to question the data:

The findings of ref. 8 have been contested, and concerns have been expressed over the validity of trends in ERA-40 that may reflect inhomogeneities or artefacts in the reanalysis rather than true climate signals.

Of course “Skeptical science” ignored all that, and pushed the conclusion they liked.

WUWT readers are familiar with this DMI Arctic temperature analysis of temperatures at 80°N and above from the WUWT sea ice reference page:

ERA40 is used as the baseline normal, now that may be in question.

Dr. Roger Pielke Sr. writes:

Indictment Of The ERA-40 Reanalysis In A New Paper “Erroneous Arctic Temperature Trends in the ERA-40 Reanalysis: A Closer Look” By Screen and Simmonds 2011

There is a new paper which is critical of the ERA-40 Reanalysis. This is an important issue as this data set has been used in long-term climate studies; e.g. see which has over 2000 citations in the peer-reviewed literature according to google scholar. The new paper is

Screen, James A., Ian Simmonds, 2011: Erroneous Arctic Temperature Trends in the ERA-40 Reanalysis: A Closer Look. J. Climate, 24, 2620–2627. doi: 10.1175/2010JCLI4054.1.

The abstract reads [highlight added]

“Atmospheric reanalyses can be useful tools for examining climate variability and change; however, they must be used cautiously because of time-varying biases that can induce artificial trends. This study explicitly documents a discontinuity in the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40) that leads to significantly exaggerated warming in the Arctic mid- to lower troposphere, and demonstrates that the continuing use of ERA-40 to study Arctic temperature trends is problematic.

The discontinuity occurs in 1997 in response to refined processing of satellite radiances prior to their assimilation into the reanalysis model. It is clearly apparent in comparisons of ERA-40 output against satellite-derived air temperatures, in situ observations, and alternative reanalyses. Decadal or multidecadal Arctic temperature trends calculated over periods that include 1997 are highly inaccurate, particularly below 600 hPa. It is shown that ERA-40 is poorly suited to studying Arctic temperature trends and their vertical profile, and conclusions based upon them must be viewed with extreme caution. Consequently, its future use for this purpose is discouraged. In the context of the wider scientific debate on the suitability of reanalyses for trend analyses, the results show that a series of alternative reanalyses are in broad-scale agreement with observations. Thus, the authors encourage their discerning use instead of ERA-40 for examining Arctic climate change while also reaffirming the importance of verifying reanalyses with observations whenever possible.”

Text in the paper includes

ERA-40 has been recently used to assess Arctic temperature trends and their vertical structure. Most notably, ERA-40 formed the basis of a now-controversial examination of central Arctic temperature trends by Graversen et al. (2008). The results of that study have been strongly contested, mainly because of concerns about the accuracy of trends calculated from ERA-40 temperatures (Bitz and Fu 2008; Grant et al. 2008; Thorne 2008; Screen and Simmonds 2010b). Yet, ERA-40 continues to be used for Arctic temperature trend analysis (e.g., Yang et al. 2010). In light of this, we show here—explicitly and more thoroughly than previous studies—that inhomogeneities in ERA-40 lead to a poor representation of Arctic temperature trends, particularly in the mid- to lower troposphere, and we demonstrate that its continued use for this purpose is problematic.”

Such an error not only affects the Arctic troposphere, but necessarily must effect the entire northern hemisphere jet stream.  It is the poleward to equatorward layer average temperature gradient which causes this wind, as we discuss, for example, in

Pielke, R.A. Sr., T.N. Chase, T.G.F. Kittel, J. Knaff, and J. Eastman, 2001: Analysis of 200 mbar zonal wind for the period 1958-1997. J. Geophys. Res., 106, D21, 27287-27290 [we used the NCEP Reanalysis in our study]

and

Christy, J.R., B. Herman, R. Pielke, Sr., P. Klotzbach, R.T. McNider, J.J. Hnilo, R.W. Spencer, T. Chase and D. Douglass, 2010: What do observational datasets say about modeled tropospheric temperature trends since 1979?  Remote Sensing, 2(9), 2148-2169.

The authors of the Journal of Climate paper [Screen and Simmonds] are  commended for alerting everyone to this serious error.

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43 thoughts on “Major flaw found in Arctic temperature reanalysis – exaggerates warming

  1. Ouch. That’s gonna leave a mark.

    Of course, “the team” will stop at nothing to explain away how “this means nothing.”

  2. I’d like to point out that the 2001 paper by Pielke, Chase, Kittle, Knaff and Eastman was funded by 2 Evil Big Oil Fossil Fuel organizations……NOAA and NASA. They laundered the funding through another Fossil Fuel shill, NCAR. /sarc
    (I’m still bitter about UCS saying anyone who disagrees with them is funded by big oil)

    But seriously,
    The Screen/Simmonds’ paper came out of the Earth Sciences section of The University of Melbourne…..which receives funding from the Australian gov’t, which generates a significant portion of its revenue from the export of coal. Oh, the irony??

  3. This raises the question of what can replace the ERA-40? And what does this mean for all the studies that used it, and the whole idea of Polar Amplification? I would really like to hear someone knowledgeable about this weigh in, as the implications of this are too big for me to fully distill with the limited knowledge I have of the ERA-40.

  4. From the Skeptical Science response to this paper:

    “Another potential contributor to amplified warming that’s investigated is changes in cloud cover. Spring is the only season that exhibits significant trends in Arctic average cloudiness and the trend is negative. However, decreased cloud cover is expected to cause surface cooling because clouds have a warming influence in spring. Thus no evidence is found of cloud cover changes contributing to recent near-surface Arctic warming.”

    WTF? There are less clouds in the spring but it gets cooler. And the sun does shine between March 21 and June 21 right up to the north pole, in fact the specific north pole gets 24 hours of sun after the between the equinoxes, with the 24-hour period sliding down to 66* on June 21st.. And, okay … where there is night during spring, night cloud cover does keep the ground warmer that cloudless nights. But I’ve been from the Tropics and the high Arctic, and I can tell you that the physics is the same when the sun shines – the ground warms up.

    Perhaps a story from the North explains this : Years ago an Inuit boy didn’t want to leave the hilltop where we were eating lunch when I saw a lightning-dancing thundercloud approaching across the tundra. He explained that in his town (then called Coppermine) lightning struck the metal jungle gym he was standing by one recess time. There was a huge flash of light, he said, and he fell down, but he was unhurt. “Maybe lightning kills you down south,” he said, “but not up here.” I insisted we seek lower ground and he agreed, though he thought I was just silly, as all southerners are.

    So maybe physics does work differently in different parts of the world. Perhaps that is Hansen and Gore’s “problem-that-is-no-problem”. In their world or part there-of, CO2 has different properties. And Skeptical Science takes rooms (or at least rent from) there.

  5. Hmm… Curious that you should link to an RC article on polar amplification by Cecilia Bitz and then go on to say that this was in jeopardy because “ref 8″ (Graversen et al, Nature) had been challenged. It’s curious because the challenge was from Cecilia Bitz (and others):

    http://www.nature.com/nature/journal/v455/n7210/full/nature07258.html

    Arctic sea ice and snow on land have retreated polewards at an alarming pace in the past few decades1. Such retreat locally amplifies surface warming through a positive feedback, which causes the Arctic surface to warm faster than the rest of the globe. In contrast, ice and snow retreat causes little warming in the atmosphere above when the stable winter atmosphere inhibits vertical heat exchange. We therefore find surprising the recent report by Graversen et al.2 in which they claim that recent Arctic atmospheric warming extends far deeper into the atmosphere than expected, and can even exceed the surface warming during the polar night. Using a different data set, we show that there is much less warming aloft in winter, consistent with the recent retreat of ice and snow, as well as recent changes in atmospheric heat transport.

    So Bitz is wrong because she was right? Very confusing….

  6. Typo alert. This might put a kink in the RC posited “polar amplification of temperature” that is expected from AGW. A previous paper published in Nature (Screen & Simmons 2010) said:
    should be “(Screen & Simmonds 2010)”—according to the PDF that was linked.

    [Thanks. Robt]

  7. The response will be “Of course this doesn’t really affect the general results”. In fact nothing ever does. Because the general result is the desired result and doesn’t require data, only computer models.

  8. Interesting…. though this brings up many questions. Anthony, I think you may have supplied us too many papers for a focused discussion.

    What I find strange here is a couple of things….. one, “(ERA-40) that leads to significantly exaggerated warming in the Arctic mid- to lower troposphere,” Ok, so ERA-40 is too high. So, what’s this? (Giss’ June temp anomaly map for the arctic) Supererly duperly too high temps?

    And the two, are we really using RSS satellites to determine the validity of ERA-40? My understanding is that both RSS and UAH satellites don’t have the orbit to accurately tell us what the temps are up there.

    I’m not trying to be a wet blanket, but I’m trying to understand what sort of precision were demanding from DMI while looking at our sources of data(GISS, UAH, RSS….), we are even more exaggerated than ERA-40. I mean, fine, if ERA-40 is wrong, its wrong, but….. this doesn’t seem kosher.

    James

  9. Above 70 north, the “accepted approximations and assumptions” that are made about the sun’s radiation, clouds, atmospheric absorption and open-water/ice-covered reflectivity are – most often- simply dead wrong.

    1. Greatly increased absorbtion of light energy into the atmosphere.

    At the equator, air mass (the atmosphere’s “thickness”) is (obviously) 1.0 Between the equator and about 60 north, air mass can be closely approximated by 1.0/(sin(latitude) ) … But that formula fails up higher because it doesn’t include the curvature of the earth, and it doesn’t include the swing of each position on the sea’s surface position back around the north pole.

    In the high Arctic, air mass over most of the hours of each day over most of the month’s of the year when the sun is actually visible range from 4.5 as high as 11.0 and 15.0 Thus, little light actually reaches the surface –even on a clear day. So, when I calculate that only 25% of the sun’s radiation (on that hypothetical perfectly clear day in the Arctic in the summer), that means that 85% of the sun’s light is absorbed in the atmosphere. It never reaches the ocean’s surface (regardless of ice-covered or open water) to be-reradiated at any wavelength.

    2. High Reflectivity off of both sea-ice and open water – in the regions where sea ice actually exists.

    Keep looking at radiation in the high Arctic – that region above 80 north latitudes. Currently, very little sea ice remains below 80 north latitude at the September minimum of 4.5 to 5.0 million km square. Thus, ANY consideration of sea-ice albedo feedback MUST be limited to looking at the today’s present conditions of a September sea ice minimum and at conditions above 80 north. Now, what “CAGW theory” – as taught by the CAGW-centric world’s universities – uses is open water albedo’s of 0.06 for water, and 0.85 for ice – as if (1) all of the the “Arctic Ocean” were sea ice and (2) all of that sea ice was floating at the Equator while (3) subjected to 24 hours per day of Equatorial sunshine. Am I exaggerating? No – I’ve read the on-line curriculums and course papers and the research papers and course exams and have these “equatorial” values endlessly repeated at every “university” and college. Actual Arctic values are simply not used. Only “global averages” and equatorial absolutes.

    What all this means is that, of what little bit of the sun’s is actually delivered to the surface, between 65% to 90% of it is immediately reflected back off of either sea ice, melt water ponds or open ocean (doesn’t matter which, they all reflect nearly identically in the Arctic latitudes) and returns to the sky at that same low incidence angle that the rays appear to come in at. General ambient background radiation WILL come in at high incident angles (because it is is being re-radiated from the sky and clouds) and WILL be more strongly absorbed by the open water and melt ponds. But that general background radiation is a small percent of the direct radiation that will be reflected.

    So, now having bounced off of the Arctic surfaces, and now still at the same wavelength that the incoming solar energy was delivered, the atmosphere now can absorb more of the remaining energy. And that energy will be at the same visible light frequencies that are “invisible” to the CO2 molecules that are so greatly feared by the CAGW equations.

    The only radiation that can be affected by changes in CO2 levels is that 10% to 15% of the direct radiation that is actually absorbed by the water (or sea ice) up north, then is re-radiated into the skies at lower energies (longer wavelengths) that can be absorbed by CO2 at any concentration. And today’s CAGW-induced global circulation models don’t “model” this real-world value.

  10. Very interesting.

    Potentially, it gives rise to very large (and significant) implications. Should the data set be replaced, and if so with what? If it is to be replaced, will there be any agreement/consensus as to the replacement data set? Will all past papers that relied upon the data set require re-evaluation and who will do this or should they simply be ignored? .

  11. RACookPE1978 says:
    August 18, 2011 at 10:08 am
    Above 70 north, the “accepted approximations and assumptions” that are made about the sun’s radiation, clouds, atmospheric absorption and open-water/ice-covered reflectivity are – most often- simply dead wrong……….
    What all this means is that, of what little bit of the sun’s is actually delivered to the surface, between 65% to 90% of it is immediately reflected back off of either sea ice, melt water ponds or open ocean (doesn’t matter which, they all reflect nearly identically in the Arctic latitudes) and returns to the sky at that same low incidence angle that the rays appear to come in at. General ambient background radiation WILL come in at high incident angles (because it is is being re-radiated from the sky and clouds) and WILL be more strongly absorbed by the open water and melt ponds. But that general background radiation is a small percent of the direct radiation that will be reflected. ……….
    The only radiation that can be affected by changes in CO2 levels is that 10% to 15% of the direct radiation that is actually absorbed by the water (or sea ice) up north, then is re-radiated into the skies at lower energies (longer wavelengths) that can be absorbed by CO2 at any concentration. And today’s CAGW-induced global circulation models don’t “model” this real-world value.”
    ///////////////////////////////////////////////////////////////////////
    No surprise there then!!!

    I have long been saying, it is the tropics that drive the system and understanding the tropics is the key to understanding how the climate/weather systems work. This is the source of the heat pump. Other areas of the globe are of far less significance and changes in the Artic whilst these may have real visible effect in practice, make little difference and often work in a manner reverse to what one may expect (may be this is mother nature’s in built self regulator eg., melting ice allows the globe to lose more heat and is therefore a brake on runaway warming).

  12. Ged says:
    August 18, 2011 at 9:37 am

    This raises the question of what can replace the ERA-40? And what does this mean for all the studies that used it, and the whole idea of Polar Amplification?

    As I understand the term – as it is most commonly used in most cases – is that Polar Amplification is caused by:
    (1) the “assumed” 24-hour day in the high Arctic. (It’s not really 24-hours of daylight, every day between the March and Sept Equinox at all points above the Arctic circle… The sun is visible at midnight above that point during SOME days of the year (depending on the latitude, the further north you go, the more days the sun is visible) at certain (very low) angles above the horizon. Right at the Arctic circle, the sun will “kiss” the horizon at midnight only one day, and will be much higher at noon. Right at the exact pole, the sun will be up all the time , swinging in a low circle all around the horizon. But there are only a few tens of thousand of sq km’s between 89 north and the pole. As you go further south towards the Arctic circle, the number of days the sun shines for 24 hours decreases significantly, and the sun’s angle at midnight averages lower and lower – which means less and less energy can be absorbed into the surface.

    (2) The amount of water vapor (90+% of the total greenhouse gas concentration near the equator) in the Arctic (and Antarctic) is limited by the very low temperatures up there. Thus, assuming CO2 is evenly distributed around the globe, the relative amounts of CO2 as a greenhouse gas increases at the poles, and thus, the assumed effect of an increase in CO2 is greater at the poles than anywhere else on the globe.

    (3) Positive sea-ice albedo feedback. If the sun is shining “straight down” onto open water, 6-7% is reflected, and the remaining (93-94%) is absorbed into the water, where is available to be re-radiated and absorbed by the CO2 in the atmosphere. (per conventional CAGW theory.) Thus, if I melt any sea ice up north, there is more open “dark” ocean water to absorb more radiation, which then heats the ocean, which re-radiates more radiation, which is absorbed by CO2 which heats the little remaining sea ice, which melts that sea ice faster, which absorbs more solar radiation, which melts the sea ice faster ….

    This concept fails when actual reflectivity at actual sea ice locations is checked. Both sea ice and open water have nearly identical indices at 1.33 and 1.31, and thus have nearly the same amounts of reflected energy – regardless of “color” of the open water compared to sea ice – in the high Arctic.

    Radiation of both sea ice and open water are even more identical (to three decimal places) so the 24-hour per day radiation of heat energy in the Arctic does not change with ice-covered water or open water.

  13. RACookPE1978 says:
    August 18, 2011 at 10:08 am

    – as taught by the CAGW-centric world’s universities – uses is open water albedo’s of 0.06 for water, and 0.85 for ice –
    ===========================================================

    Thanks, man, I’ve been looking for that…… it is hilarious, but if that’s what they’re applying in the arctic, then yes, their models will be wrong. You wouldn’t happen to have a link that shows those assumptions?

  14. James Sexton says:
    August 18, 2011 at 10:42 am

    RACookPE1978 says:
    August 18, 2011 at 10:08 am

    – as taught by the CAGW-centric world’s universities – uses is open water albedo’s of 0.06 for water, and 0.85 for ice –
    ===========================================================

    Thanks, man, I’ve been looking for that…… it is hilarious, but if that’s what they’re applying in the arctic, then yes, their models will be wrong. You wouldn’t happen to have a link that shows those assumptions?
    ===========================================================

    For “jest” one problem with how climate “science” is being graded – not taught, mind you, but what today’s students are being graded on – see the “answers” to problem 4 in this mid-term exam:

    http://isnap.nd.edu/Lectures/phys20054/midterm_exam_solution.pdf

    Now, can you count the errors and omissions and assumptions being made … by the person who wrote the “answer” to this mid-term question?

  15. ” Thus, the authors encourage their discerning use instead of ERA-40 for examining Arctic climate change while also reaffirming the importance of verifying reanalyses with observations whenever possible.”

    Now that will never work.

  16. RACookPE1978 says:
    August 18, 2011 at 11:26 am

    Now, can you count the errors and omissions and assumptions being made … by the person who wrote the “answer” to this mid-term question?
    =======================================================================
    lol, thanks again….. especially for the link! But, to avoid displaying my ignorance, I’ll abstain from trying to count the errors, omissions and assumptions……. mostly because my views on climate energy forcings are self-taught, so I’ve got to interpret the colloquial vernacular. For instance, what do the epsilon represent? The alpha obviously is the albedo…..that’s funny…. they assume equal incoming solar forcing…..

  17. Well, ERA-40, flawed as it may be, is becoming increasingly fashionable among mainstream climate scientists.

    This is the number of articles by year on Google scholar containing the terms both “Arctic” & “ERA-40″ (Articles excluding patents – at least summaries):

    1995 0
    1996 1
    1997 8
    1998 13
    1999 10
    2000 23
    2001 25
    2002 28
    2003 52
    2004 71
    2005 142
    2006 221
    2007 280
    2008 355
    2009 377
    2010 501

    Clearly, it is increasing exponentially, with a doubling time of ~2 years. If it goes on like this, by the end of this century the annual number of papers connecting the Arctic to the ERA-40 reanalysis product is projected to be 17,592,186,044,416,000 (17.6 quadrillion). It is certainly worse than we thought.

  18. 1910-1940 Arctic warming was several times more “amplified” as 1975-2005 allegedly anthropogenic warming.

    Winter temperatures are as “warm” as in 1940s and those should be affected by CO2 most due to dry and cold air up there. This single chart falsifies the whole pseudo scientific AGW theory.
    Temperature in Arctic is a function of Atlantic SST anyway, which goes 30 years up and 30 years down.

  19. Epsilon (the greek “e”) as used in the “solution” to problem 4 of that mid-term exam is approximately the “emissivity” of pure ice and pure water, rounded to 2 decimal places. If so, then “1-e” is (I assume) supposed to be the proportion of absorbed energy not “re-radiated” from either substance. I think. 8<)

  20. “that leads to significantly exaggerated warming in the Arctic mid- to lower troposphere,”
    ================================================================
    and one person is going to argue that the Arctic is even more sensitive, because temps were lower and more ice melted….

    …..another person is going to argue that less ice lets more heat escape

    now what…………….LOL

  21. But don’t the models show most of the warming is coming from the poles? Don’t we have a lack of sensors in this region and plug estimates into the climate models?

  22. Pedant alert!

    “Such an error not only affects the Arctic troposphere, but necessarily must effect the entire northern hemisphere jet stream.”

    I believe the noun “effect” should be the verb “affect”.

  23. The paper seems to be criticizing mostly the upper air temps of ERA-40 in the Arctic, which seemed to indicate that the stronger Arctic surface warming recent years was more related to changes in atmospheric circulation than surface related feedbacks from loss of ice cover. The paper says that the Arctic upper air trends contain a spurious warming shift in about 1997 that creates a false impression of stronger upper air than surface warming in the Arctic. Basically they are defending the “orthodox” view that polar amplification is supposed to be related to ice-albedo feedback more so than some circulation effects.

    On a global scale ERA-40 seems to also have some discontinuities in air temperatures that cause it to warm spuriously too much compared to satellite and radiosonde records that agree with one another well (ie especially UAH). The potential for these discontinuities always means you have to be careful about using reanalysis data for various purposes, especially when and where it disagrees with data from other sources that agree well with one another.

    Personally I think that the “recent” polar amplification isn’t particularly interesting, what is interesting is the way the “amplification” evolved in the past. In particular there were two periods, one of warming and another of cooling, that occurred before the late twentieth century warming. During those episodes of warming and cooling, the coefficients relating Arctic air temperature change to global temperature change appear to have been much larger (especially during the cooling mid century) suggesting that the situation with amplification is not so simple as global climate changes and the Arctic changes X times more:

    http://www.lanl.gov/source/orgs/ees/ees14/pdfs/09Chlylek.pdf

  24. What I find interesting is the that max temperature (around day 200) has varied very little (less than a degree) since 1958. The warming appears not to be monotonically increasing with season, rather it has been static in the summer (less ice?, more sun?) and quite variable in the winter. That would seem to suggest that temperature is not causative but rather a consequence of other driving factors (i.e. sea ice drives temperature, not the other way around). The lack of summer season temperature rise is rather startling. The profound repitition is scary as well.

  25. When we – a WUWT reader – loaded all of the summertime temperatures from the DMI records for 80 north latitude from 1958 through 2010, the long term trend is actually declining, and the most recent years are decreasing the fastest.

  26. “Berényi Péter says:
    August 18, 2011 at 12:09 pm
    Well, ERA-40, flawed as it may be, is becoming increasingly fashionable among mainstream climate scientists.

    This is the number of articles by year on Google scholar containing the terms both “Arctic” & “ERA-40″ (Articles excluding patents – at least summaries):

    1995 0
    {SNIP}
    2009 377
    2010 501

    Clearly, it is increasing exponentially, with a doubling time of ~2 years. If it goes on like this, by the end of this century the annual number of papers connecting the Arctic to the ERA-40 reanalysis product is projected to be 17,592,186,044,416,000 (17.6 quadrillion). It is certainly worse than we thought.”

    If you can model that, I think I can find you a grant!

  27. In fairness to the good folk at the NSIDC, their web site does at least mention the effects of low angles of incidence and reflection. But then they end up repeating the same 8% (open water) and 80% (new snow) values everybody else repeats – since everybody else abviously feels comfortable quoting the NSIDC. Where the Arctic sea ice actually is – real world up near the pole at 80+ degrees latitude – the angle of incidence for the sun’s rays, on all but a few days of the period between June and July when the sun (at noon) is higher, is between 0 and 20 degrees.

    http://nsidc.org/arcticmet/factors/radiation.html

    Albedo

    Incoming solar radiation that strikes the earth’s surface is partially reflected and partially absorbed, in proportion to surface reflectivity (albedo). Darker surfaces have a lower albedo and absorb more solar energy than do lighter surfaces. The albedo of a surface is also a function of the incidence angle of solar radiation (that is, the amount of solar energy a surface absorbs will depend on the solar altitude).

    Newly fallen snow has an albedo of approximately 0.90, meaning that it reflects about 90 percent of incoming radiation. In contrast, melting snow has an average albedo of 0.50, meaning that it absorbs 50 percent and reflects 50 percent of the incoming radiation. Because a darker surface absorbs more solar radiation, snow covered by dust (dirty snow) melts faster than clean snow. The albedo of sea ice varies with ice age, but when snow covered is on the order of 0.70.

    Open water absorbs the most radiation of all arctic surfaces. With an albedo of about 0.08, it reflects only 8 percent of the incoming radiation. However, the variation of albedo with solar altitude is especially pronounced for the surfaces of oceans and lakes. The albedo of a water surface increases with decreasing solar altitude and approaches a mirror-like 100 percent near sunrise and sunset, or when the sun is low in the arctic sky.

    Important changes in surface albedo can occur seasonally. Over land, heavy winter snow cover increases surface albedo considerably. In middle and high latitudes, significant increases in surface albedo accompany the winter formation of lake and sea ice.

  28. FORECAST THROUGH MONDAY…EAST OF 155W…THE MAIN PACK WILL MOVE TO
    THE WEST 10 TO 20 NM.

    FORECAST THROUGH MONDAY…WEST OF 155W…LITTLE CHANGE IN ICE
    POSITION THROUGH FRIDAY. THE ICE WILL MOVE TO THE SOUTHWEST 15 TO 25
    NM SATURDAY THROUGH MONDAY.

  29. @Gary Turner. You are right, but the verb “affect” is rarely used now. For some reason everyone wants to use “impact” instead. It makes every causal chain sound like a car crash.

  30. And for us non-technical types, does this mean that Hawaiian shirts and board shorts might not be appropriate for our sailing holiday in the Arctic Ocean?

  31. But…but…the science was “settled”!

    Gosh, if you can’t trust climate scientists, who can you trust?

  32. Double pedant alert!

    Gary Turner says:
    August 18, 2011 at 1:20 pm

    Pedant alert!

    “Such an error not only affects the Arctic troposphere, but necessarily must effect the entire northern hemisphere jet stream.”

    I believe the noun “effect” should be the verb “affect”.

    “effect” is also a verb, but means something like create, or produce.
    >:-)

  33. I have to say all that red colour in the arctic over the years has always been a bit suspicious to me. I didn’t realize that not only were temps being extrapolated 1200km from northern thermometers but they were also fudging the vertical temp distribution. Does the new paper tell what the temp anomaly should be?

  34. Winter is closing in at high latitudes. Rossby Waves from the WPAC have amplified the pattern. Looking at the long range the strong Bering Sea lows are lining up. Out next week some very deep winter like lows show up, sliding down well into the Gulf of Alaska. Summer is essentially over in the far Westerly longitudes of the mid and upper NH latitudes.

  35. Tim Beatty says:
    August 18, 2011 at 1:25 pm

    Well, The temps are very stable because all extra heat goes into melting ice. What is more interesting, is if the ERA40 is too high, then winter temps — which have been mostly ABOVE the green line lateley, seem to indicate really high temps?

  36. Satellite temps for the globe and the Arctic taken from UAH (Roy Spencer) show a pronounced warming in the Arctic.

    Global decadal trend = 0.14C

    Arctic decadal trend = 0.48C

    We trust Roy Spencer and UAH satellite temps more than surface records, right?

    When we – a WUWT reader – loaded all of the summertime temperatures from the DMI records for 80 north latitude from 1958 through 2010, the long term trend is actually declining, and the most recent years are decreasing the fastest.

    That is because the area North of 80 degrees lat is ice-bound all year round (minus floes that open and close), and the temperatures there will not rise above the temperature of the ice – zero centigrade. Summertime temps in that region will not change much until that area begins to see less ice in summer.

    This was explained here by Steve Goddard ages ago, as well as at his website. I also emailed DMI about it and got this response

    “The surface in the +80N area is more or less fully snow and ice covered all year, so the temperature is strongly controlled by the melting temperature of the surface. I.e. the +80N temperature is bound to be very close to the melt point of the surface snow and ice (273K) and the variability is therefore very small, less than 0.5K. I am sure you will find a much clearer warming trend in the same analysis applied to the winter period.”

    And indeed, that is what you find, a warming trend in winter for that region.

    (The conversation on that, plus the original posting of the email, came from here, and you can see Goddard confirming upthread here)

    Whether or not GISS exaggerates Arctic amplification is one thing, but there is little doubt that the Arctic IS warming faster than than the globe.

  37. RACookPE1978 says:
    August 18, 2011 at 10:08 am
    Above 70 north, the “accepted approximations and assumptions” that are made about the sun’s radiation, clouds, atmospheric absorption and open-water/ice-covered reflectivity are – most often- simply dead wrong.

    A bit like your posts then, which are full of errors.

    1. Greatly increased absorbtion of light energy into the atmosphere.

    At the equator, air mass (the atmosphere’s “thickness”) is (obviously) 1.0 Between the equator and about 60 north, air mass can be closely approximated by 1.0/(sin(latitude) )

    Obviously not since this would be cosec(latitude) which would have a value of ∞ at the equator and 1 at the pole!

    In the high Arctic, air mass over most of the hours of each day over most of the month’s of the year when the sun is actually visible range from 4.5 as high as 11.0 and 15.0 Thus, little light actually reaches the surface –even on a clear day. So, when I calculate that only 25% of the sun’s radiation (on that hypothetical perfectly clear day in the Arctic in the summer), that means that 85% of the sun’s light is absorbed in the atmosphere. It never reaches the ocean’s surface (regardless of ice-covered or open water) to be-reradiated at any wavelength.

    Since air is transparent to solar insolation (except for the UV absorption by O3 and some small H2O and CO2 bands in the IR tail) by what mechanism do you propose it is absorbed? Clouds and GHG gases absorb about 19% of insolation not 85%!

    2. High Reflectivity off of both sea-ice and open water – in the regions where sea ice actually exists.

    Keep looking at radiation in the high Arctic – that region above 80 north latitudes. Currently, very little sea ice remains below 80 north latitude at the September minimum of 4.5 to 5.0 million km square. Thus, ANY consideration of sea-ice albedo feedback MUST be limited to looking at the today’s present conditions of a September sea ice minimum and at conditions above 80 north. Now, what “CAGW theory” – as taught by the CAGW-centric world’s universities – uses is open water albedo’s of 0.06 for water, and 0.85 for ice – as if (1) all of the the “Arctic Ocean” were sea ice and (2) all of that sea ice was floating at the Equator while (3) subjected to 24 hours per day of Equatorial sunshine. Am I exaggerating? No – I’ve read the on-line curriculums and course papers and the research papers and course exams and have these “equatorial” values endlessly repeated at every “university” and college. Actual Arctic values are simply not used. Only “global averages” and equatorial absolutes.

    You are indeed exaggerating.

    What all this means is that, of what little bit of the sun’s is actually delivered to the surface, between 65% to 90% of it is immediately reflected back off of either sea ice, melt water ponds or open ocean (doesn’t matter which, they all reflect nearly identically in the Arctic latitudes)

    They don’t, as shown here: http://www.arctic.noaa.gov/npole/2011/images/noaa2-2011-0716-013730.jpg
    Also your numbers are way off, to reflect 65%+, the incident radiation would have to be at an angle of 85º+
    RACookPE1978 says:
    August 18, 2011 at 10:30 am

    (3) Positive sea-ice albedo feedback. If the sun is shining “straight down” onto open water, 6-7% is reflected, and the remaining (93-94%) is absorbed into the water, where is available to be re-radiated and absorbed by the CO2 in the atmosphere. (per conventional CAGW theory.) Thus, if I melt any sea ice up north, there is more open “dark” ocean water to absorb more radiation, which then heats the ocean, which re-radiates more radiation, which is absorbed by CO2 which heats the little remaining sea ice, which melts that sea ice faster, which absorbs more solar radiation, which melts the sea ice faster ….

    This concept fails when actual reflectivity at actual sea ice locations is checked. Both sea ice and open water have nearly identical indices at 1.33 and 1.31, and thus have nearly the same amounts of reflected energy – regardless of “color” of the open water compared to sea ice – in the high Arctic.

    No, wrong again, if we were talking about pure ice such as you might have in your fridge it would be close (but you have them backwards in any case). In reality the sea ice (especially if covered by snow) appears white (grey) because of all the bubbles and air spaces which cause back-scattering and therefore a much higher albedo.

    Radiation of both sea ice and open water are even more identical (to three decimal places) so the 24-hour per day radiation of heat energy in the Arctic does not change with ice-covered water or open water.

    Again wrong, the temperature of sea-water will have a minimum temperature of ~271K whereas sea-ice will have a maximum of 273K and as low as 240K, the radiation depends on T^4 so that is a large difference, certainly not the same to 3 dps!

    RACookPE1978 says:
    August 18, 2011 at 4:01 pm
    Where the Arctic sea ice actually is – real world up near the pole at 80+ degrees latitude – the angle of incidence for the sun’s rays, on all but a few days of the period between June and July when the sun (at noon) is higher, is between 0 and 20 degrees.

    You don’t appear to know what the angle of incidence is, it’s the angle made with the normal. In any case even using your definition it would be between 0 and 33º.

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