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Solar spectral stumper

Filed under: — gavin @ 7 October 2010

It’s again time for one of those puzzling results that if they turn out to be true, would have some very important implications and upset a lot of relatively established science. The big issue of course is the “if”. The case in question relates to some results published this week in Nature by Joanna Haigh and colleagues. They took some ‘hot off the presses’ satellite data from the SORCE mission (which has been in operation since 2003) and ran it through a relatively complex chemistry/radiation model. These data are measurements of how the solar output varies as a function of wavelength from an instrument called “SIM” (the Spectral Irradiance Monitor).

It has been known for some time that over a solar cycle, different wavelengths vary with different amplitudes. For instance, Lean (2000) showed that the UV component varied by about 10 times as much as the total solar irradiance (TSI) did over a cycle. This information (and subsequent analyses) have lent a lot of support to the idea that solar variability changes have an important amplification via changes in stratospheric ozone (Shindell et al (2001), for instance). So it is not a novel finding that the SIM results in the UV don’t look exactly like the TSI. What is a surprise is that for the visible wavelengths, SIM seems to suggest that the irradiance changes are opposite in sign to the changes in the TSI. To be clear, while the TSI has decreased since 2003 (as part of the descent into the current solar minimum), SIM seems to indicate that the UV decreases are much larger than expected, while irradiance in visible bands has actually increased! This is counter to any current understanding of what controls irradiance on solar cycle timescales.

What are the implications of such a phenomena? Well, since the UV portion of the solar input is mostly absorbed in stratosphere, it is the visible and near-IR portions of the irradiance change that directly influence the lower atmosphere. Bigger changes in the UV also imply bigger changes in stratospheric ozone and temperature, and this influences the tropospheric radiative forcing too. Indeed, according to Haigh’s calculations, the combination of the two effects means that the net radiative forcing at the tropopause is opposite in sign to the TSI change. So during a solar minimum you would expect a warmer surface!

Much of the longer term variance in solar output has been hypothesised to follow what happens over the solar cycle and so if verified, this result would imply that all current attributions to solar variability of temperature changes in the lower atmosphere and surface ocean would be of the wrong sign. Mechanisms elucidated in multiple models from multiple groups would no longer have any validity. It would be shocking stuff indeed.

Conceivably, there might be another missing element (such as a cosmic-ray/cloud connection) that would counteract this physics and restore the expected sign of the change, but no-one has succeeded in finding any mechanism that would quantitatively give anything close the size of effect that would now be required (see our previous posts on the subject).

So is this result likely to be true? In my opinion, no. The reason why has nothing to do with problems related to the consequences, but rather from considerations of what the SIM data are actually showing. This figure gives a flavour of the issues:

(courtesy Judith Lean). Estimates of irradiance in three bands are given in each panel, along with the raw measurements from various satellite instruments over the last 30 years. The SIM data are the purple dots in the third panel. While it does seem clear that the overall trend from 2003 to 2009 is an increase, closer inspection suggests that this anti-phase behaviour only lasts for the first few years, and that subsequently the trends are much closer to expectation. It is conceivable, for instance, that there was some undetected or unexpected instrument drift in the first few years. The proof of the pudding will come in the next couple of years. If the SIM data show a decrease while the TSI increases towards the solar maximum, then the Haigh et al results will be more plausible. If instead, the SIM data increase, that would imply there is an unidentified problem with the instrument.

In the meantime, this is one of those pesky uncertainties we scientists love so much…

254 Responses to “Solar spectral stumper”

  1. 51
    Dan H. says:

    Papers like the one by Gray and Livingston show the solar contribution of the recent temperature increase to be significant. According to their report, the sun may have contributed 0.28C to the observed 0.6C of warming from 1979-1998. Reports of reduced solar activity since may help to explain the more recent decrease.
    All in all, too many people (alarmists and deniers) are using single reports of solar activity to (dis)prove global warming. The way this report was presented in two of the articles listed above shows that. The role of the sun needs to be fully understood in order to place it role in the entire climate debate.

    [Response: Sure, but the numbers you quote are much larger than can be justified – do you have a proper cite? – gavin]

  2. 52
    Rich Creager says:

    Mark Green (48) Actually sunspots are cooler than the rest of the sun’s surface, which is why they appear dark.

  3. 53
    Fred Moolten says:

    To Dan (50) and Thomas (46) –

    Dan – The “secular trend” of 0.014 K/year you mention refers to the temperature of the sun (at an average temperature of about 5800 K), not the temperature of the earth, and the authors point out that the “trend” is not necessarily long term. It would be unlikely to dramatically affect temperatures on Earth at an average of 288 K.

    Thomas – I agree that TSI can’t be explained as the simple result of black body emission by a homogeneous entity. Regarding UV and TSI, they do seem to be more or less in phase (i.e., they change with the same sign), but the UV variance exceeds that of TSI. The real challenge of the recent results, however, if they are interpreted as more than transient effects, would be to explain a phenomenon that appears to imply that some major source of solar radiation may be hotter at solar minimum than at solar maximum, thereby causing an increase in irradiance at visible frequencies. This would be a revolutionary finding indeed, but the Gray and Livinston paper (see my link in #45) indicates that phase discordances between TSI and visible irradiance (if the latter is a reflection of solar temperature) are probably transient phenomena, while over the entire cycle, the two are correlated. In that case, the newly reported findings would not greatly alter our current thinking about the relationships between solar activity and our climate over the course of multiple solar cycles or even over the entire course of a single cycle.

  4. 54
    Edward Greisch says:

    “Upper parts of the solar atmosphere”: The UV from the Corona varies by 5 orders of magnitude. This gives us sunburns, but I thought that the energy was rather small compared to total solar output. The corona also makes X-rays. Are we talking photosphere vs corona? Isn’t the corona powered by magnetic storms? Do we need to talk about what the sun is doing in more detail to figure out where the UV we are talking about comes from?

  5. 55
    Dan H. says:

    Thanks Fred,
    I missed that. I think the “secular” threw me.

  6. 56
    Geno Canto del Halcon says:

    RE: Gavin’s comment, No. 21: What you really should have is three instruments. If you have two instruments with contrary results, you can’t know which one is right.

    [Response: True (cf. Rendezvous with Rama for the geeks among us). Good luck arguing for a tripling of the budget though… ;) – gavin]

  7. 57
    Nick Gotts says:

    Reports of reduced solar activity since may help to explain the more recent decrease. – Dan H.

    Which decrease is that?
    Oh, right, the one that hasn’t happened.

  8. 58
  9. 59
    Aaron Lewis says:

    Re Gavin’s inline comment on 21
    At first, we just had experts in data quality grade our data (i.e., we had (third party) senior chemists go back and check all of the work line by line, and flag problems with analytical results.) Then, as we moved to solid state analysis was more checking proper sampling, calibration, maintenance, and database operation. (Gavin, When was the last time you had data that had been carefully reviewed, line by line by a third party expert with access to ALL lab logs?)

    Eventually we got to DQO ( where the entire data collection process was planned to support a decision and risk management process, such that critical decisions were allocated the resources to get the better data that such important decisions required.

    Yes, we have important decisions to make and we need data of appropriate quality to base those decisions on – whatever it takes.

    A few space rockets are no more expensive than the environmental sampling at US DOE sites Hanford and Savannah River. And, a couple of contaminated nuclear production sites are not as critical to our future as global climate change.

    A good decision on climate change is worth the cost of good data.

  10. 60
    Eli Rabett says:

    Aaron Lewis would do well to hi his-self over to NASA’s IVV for an education on mission software verification. As to Savannah River, Eli knows a bit more than a bit about the chemistry of the clean up program, and to call it a very far behind schedule mess with questionable chemical process design is to be very charitable.

  11. 61
    Eli Rabett says:

    #32, Gavin, one can err by omission.

  12. 62
    Jacob Mack says:

    Thanks Jim for the clarification

  13. 63
    Jacob Mack says:

    Eli # 59: well said.

  14. 64
    Rod B says:

    Gavin, excuse me if I refuse the stereotype people on both sides of the question want me to accept. I am neither a denier nor a contrarian. The fact that many have hijacked those terms so they can be applied much more broadly to anyone they don’t particularly like is nothing more than name calling. I’ll stick with the accepted meaning of the terms, not the bastardized terms.

  15. 65
    Ray Ladbury says:

    Aaron Lewis says: “A few space rockets are no more expensive than the environmental sampling at US DOE sites Hanford and Savannah River.”,

    OK, you owe me a new keyboard due to coffee damage. Dude, do you realize it costs $10000 to launch a can of Coke into space! I’m sorry, Aaron, but doing things in space has always been expensive, it is still expensive, and it will always remain expensive.

    I believe you have succumbed to the fallacy that everything you don’t understand must be simple. The cure: Understand spaceflight. I’d be happy to explain things to you.

  16. 66
    Thomas says:

    Nick @56: The current solar minima, that we are jut coming out of is unprecedented in the modern record, this minima is deeper and longer than has been seen for several decades. How, TSI versus sunspot numbers vary on time scales longer than a solar cycle, I think is still not known.

  17. 67
    Ray Ladbury says:

    Thomas, The last solar minimum was hardly unique. You only have to go back about a centur to find minima as deep or as long. Yes, it was an odd cycle, but not that odd.

  18. 68
    Hank Roberts says:

    > deeper and longer than has been seen for several decades
    Several decades is not very long, in solar cycles.

  19. 69
    Thomas says:

    Ray 65: Unique as far as our ability to accurately measure TSI. So yes such “events” have ocurred in the past, but we don’t have good irradiance data on them.

  20. 70

    Ray @ 65:

    “Last”? We’re still having spotless days. The end of the minima is being called a bit early …

  21. 71


    Triple redundancy = MilSpec

    Should be easy to accomplish. Let’s see, we first need an informed public on the issues = no spin in the media = so politicians will be properly motivated to act = no special interest influence in campaigns and governance = overturning Supreme Court decisions: Citizens United vs. FEC (2010); Buckley vs. Valeo (1976); Santa Clara vs. Southern Pacific Railroad (1986) = politicians do the right thing because it gets them votes + meaningful market transparency regulation imposed + antitrust laws increased for effect and enforced = greater transparency in markets + stronger fair competition = eliminating derivative market systems + stronger shareholder rights = less artificial inflation = more money can go to science = potential for mil spec sat systems.

    No problem ;)

    Fee & Dividend: Our best chanceLearn the IssueSign the Petition
    A Climate Minute: Natural CycleGreenhouse EffectClimate Science HistoryArctic Ice Melt

  22. 72


    Santa Clara vs. Southern Pacific Railroad (1986)

    supposed to be

    Santa Clara vs. Southern Pacific Railroad (1886)

  23. 73
    William says:

    In reply to Ray Ladbury:

    \Thomas, The last solar minimum was hardly unique. You only have to go back about a century to find minima as deep or as long. Yes, it was an odd cycle, but not that odd.\

    Ray the solar activity in the last 40 years of the 20th century was the highest in roughly 10,000 years. What is unusual about cycle 24 is the abrupt change from a very high activity to low activity. (My point there is more to the scientific problem than the number of sunspots. For example what creates the sunspots and why has that mechanism suddenly changed.)

    There are two related scientific questions. Why and how can the sun change and how can the solar changes affect the planet.

  24. 74
    Hank Roberts says:

    > solar activity was the highest

    Archibald says so, but why do you find that believable?
    Do you have a source in the literature using a reliable proxy?
    Why do you consider it reliable?

  25. 75
  26. 76
    Geoff Wexler says:

    Re #49 Gavin’s response

    When sunspots intensify, less energy is lost from the Sun > a ‘solar greenhouse’ slightly analagous to ours except that it would be at visible wavelengths.

    Of course you do not have to have energy balance on the Sun , but it still seems to me that a reduction of outgoing radiaton at one point might imply a rise in temperature somewehere else in the surface region. Could that be a way of thinking about the faculae? It would not necessarily change the numbers.

  27. 77
    Ninderthana says:

    Has it ever occurred to anyone here that there could be another critical factor that influences average global temperatures?

    Charles Keeling and Timothy Whorf (2000) [PNAS, Vol. 1910, No. 8, pp. 3814 – 3819], found that changes in the Earth’s global temperature record for the last 120 years showed spectral properties that matched those seen in the peak Lunar tides.

    What if the properties of the lunar orbit that were responsible for the timing of the peak lunar tides (i.e. changes in the shape and orientation of the Lunar orbit) were some how synchronized with long-term changes in the level of solar activity.

    It has long been argued that the changes in solar activity that could effect global temperatures (e.g. TSI) are too small to be of any significance unless they are “amplified” by some, as yet, unknown mechanism. Some people have proposed that it is large variations in the UV over the course of the solar cycle that are responsible. However, if changes in the shape and orientation of the Lunar orbit are synchronized with long-term changes in solar activity, this would naturally produce an apparent “amplification” of the Sun’s effect on global temperatures without
    any [direct] need to invoke changes in the TSI of the Sun.

  28. 78
    Thomas says:

    Geoff: If solar activity does effective the net radiation from the solar surface, then the delta in energy must go inot/from some energy store, magnetic, or thermal/gravitational. Of course if you warm up a layer of the sun, it expands against gravity, and paradoxically it can cool enough that net radiation could decrease. So we could have two effects from a sunspot, which is dark mainly because it supresses thermal convection (effectively magnetic damping of conductive fluid motion (magnetohydrodynaimcs). The most obvious is that perhaps the heat is simply deflected horizontally, and comes out nearby. But if it causes the outer layers to either expand (store energy) or contract, it would be possible for the net solar output to be temprarily modulated by the activity. Of course the magnetic energy, which is taken from the fluid motion of convection heats the Chromosphere and corona, and drives things like the solar wind, and transitory things like flares and coronal mass ejections etc. So what is actually happening gets pretty complicated pretty quickly. Any layer of the sun that is not in energy balance (flux coming up from above balancing flux lost upwards) will be heating/cooling because of the imbalance.

  29. 79

    Its not really a stumper.

    Playing a contrarian premise, in this case, extra UV in solar minimas give somehow more surface heat.. -As it should since solar cycle 24 coincides with extreme warming temperatures- except during darkness, the long night and or low sun elevations deny this utterly:

    especially the Arctic even the Antarctic is warming more strongly then with places having higher sun elevations. Therefore its hard to confirm any UV impact if any there exists some…

  30. 80
    Matt Andrews says:

    Thanks, Gavin, nice overview.

    Typo in para 3: “What are the implications of such a phenomena?”: should be “such a phenomenon”. Or “such phenomena” :)

  31. 81
    Hank Roberts says:

    (Most Google hits are people posting it in comments, misunderstanding it)

  32. 82
    Dean says:

    Ray (re. #65)

    Actually, costs aren’t that high. Ok, the Shuttle is at least that high, but satellite launches average around $2500/pound. Some cost as low as 1500/lb.

    It should be noted that this link shows the shuttle launch costing $300M. NASA currently admits that it costs $450M and if you add in all the costs, it’s probably closer to $750M/$1B a launch.

  33. 83
    Ray Ladbury says:

    Great. Now geta 30 year rising temperture trend out of lunar tides. And when you are done there, how about stratospheric cooling at the same time.

  34. 84
    Robin Rutherford says:

    Hello, I live in rural New Zealand in the central North Island in a farming area. I have been noticing for two or three years the evidence of severe burn in spring, summer and autumn, on plants and on people who are outside a lot. In the farming newspapers you will often see photos of farmers whose faces are extremely reddened. In my area in the summer you see the same extremely reddened faces amongst outdoor workers even after one sunny day . I asked Niwa to put a spectrometer at my place to check it out the UV levels, which they did but the person doing the work left before the results were analysed and I have heard nothing further. I am sure UV levels here, with clear air, and an altitude of 300m are actually very very high. It concerns me. To me something seems very different to three years ago, when none of the facial burning was noticeable.

  35. 85
    jeannick says:

    Some good data can be got out of an instrument if the drift is constant
    even down down to near death

    The satellite record is not really long enough to use it as gospel ,
    it’s more indications than boiler plate solid ,
    As for the Sun physic , if one take predictions as the standard for good science , astronomers can make prediction on the planets position a couple of decades in advance and be right 100%
    Solar physicists at the Marshall center have just had eggs on their faces predicting the current cycle ,they keep adjusting their predictions to fit the graph of C24
    Solar physic is explorator territory still

    I would take all solar sciences as brave educated guesses for the while .
    but , I’m of a skeptical nature ,
    if it doesn’t predict well ,it is not much good and back to the blackboard

  36. 86

    #84, Robin: This may help:

    UV getting through has something to do with Total Atmospheric Ozone depletions, which is keenly related to temperature of the stratosphere, in the past, always very cold, but now coupled with the presences of CFC photo-chemicals. You live not far away from a region not rich in stratospheric ozone.
    Suggest looking at “Toast” , on a regular basis, and or use the archives to see if you can explain past severe sunburns.

  37. 87
    Ray Ladbury says:

    I envy you your location. My wife and I both loved New Zealand. I would imagine your UV flux is affected by the ozone hole more than solar variability. However, we’d be very interested in the results you hear. Do protect yourself from the UV, please.

  38. 88
    Patrick 027 says:

    Re 81 Hank Roberts – a bit OT but that’s interesting stuff; I wish I could find somewhere where the relative strength of the tides is given – say as a % change from average (or from average spring tides specifically). I wouldn’t think that the variance is all that big, outside of half a lunar month (where it should be a ~ +/- 50 % change from average) (and before going into geologic time, of course). Also I don’t recall seeing anything about variations in the lunar orbit’s eccentricity in those papers. Also, the diurnal and semidiurnal tides could be expected to respond somewhat differently to the moon’s inclination to the ecliptic at times of syzygy (PS if the tides followed equilibrium, the diurnal tides would be largest in midlatitudes and the semidiurnal tides would be largest in the tropics; of course, if the tides followed equilibrium, we wouldn’t have noticed them without scientific instruments! (the ocean and crust would move together).) I recall once reading of a glacier at sea level with a tide-dependent flow rate; I can imagine a potential threshold behavior for that sort of thing, but don’t expect longer-period tidal cycles acting through that or the following paranthetically-stated mechanism it would affect global climate much (PS thinking of tidal currents through islands breaking up sea ice…).

  39. 89
    Patrick 027 says:

    PS to clarify, that last paranthetical statement was just speculation directed by curiosity; I know of no known examples of that particular phenomenon.

  40. 90
  41. 91
    Uncle pete says:

    @ 84 Rutherford.
    Any relation to “The ” Rutherford ? He also was a New Zealander as you probably know.

  42. 92
    Paul Levy says:

    Jeannick #85 – I don’t agree with your statement that “predictions are the standard for good science”. Some physical systems simply can’t be predicted with any accuracy beyond fairly short timescales – this is the main point of chaos theory. It doesn’t mean there’s anything wrong (per se) with the model.

  43. 93
    John E. Pearson says:

    84 Robin:

    If sunburn incidence is rising it should show up in hospital records. You might check with local hospitals who probably keep records of that sort of stuff.

  44. 94
    Didactylos says:

    Dean, that’s to low earth orbit. Geosynchronous costs more, and getting to L2 is even more expensive.

    But the biggest launch cost is probably insurance. When you are launching something like Envisat, the result of a 2.3 billion EUR project, the 120 million EUR for the launch is almost trivial. That was a polar orbit (out of reach for a Dnepr vehicle) and it’s too heavy for nearly everything except Ariane 5. The cheap options just melt away like morning dew.

  45. 95
    William says:

    In reply to Hank Robert’s comment 75 that included a link to this paper.

    Excerpt from above paper.
    “In Sects. 5 and 6, we show that inadequate account of the number of degrees of freedom leads to a large underestimate of the confidence interval found in LMKC, and that the remaining significance is only due to coincidence of high solar activity with anthropogenic forcing over the last 50 years.”

    There does seem to be agreement that the solar magnetic cycle was very activity in the last part of the 20th century. The papers that allege to disprove the solar modulation of climate (including the paper linked to above) do not consider other solar mechanisms and changes, such as solar wind bursts. TSI is one of five different solar physical parameters that could modulate climate. Heliosphere strength (which modulates GCR), Solar wind bursts (that removes GCR via modulation of the global electric circuit), TSI, UV level, and what ever is causing the ionosphere to change in height (assuming that change is caused by a solar change). My point is that if one does understand how the sun has changed in the past and how the solar changes affect climate one cannot prove or disprove its affect on climate in the later part of the 20th century.

    An example would be Tinsley and Yu’s assertion that an increase in GCR can cause an increase in winter storm severity. If solar wind bursts remove GCR, they could mitigate and mask the effect, making it appear that GCR levels do not affect planetary climate. There is a comment in this thread that there is no correlation of GCR levels and planetary temperature in the later part of the 20th century (i.e. Planet warmed during some periods when GCR levels high.) Solar wind bursts were also high during the periods when there was a lack of correlation.

    In the past there is alleged to be correlation of cosmogenic isotopes C14 and Be10 changes with climate change. There is not however agreement as to what solar mechanism could cause changes to the climate in the past or even what was the magnitude of the changes in the climate the past.

    Cycle 24 seems to be anomalous for a number of reasons. There is an observed abrupt change from a very high level of magnetic cycle activity to low or possible to an interruption in the solar magnetic cycle. It is not clear from a solar physics standpoint why there is a linear reduction in the magnetic field strength of individual sunspots hence there is push back whether Livingstone and Penn’s observation is correct. There is not agreement why the 2000 gauss to 3000 gauss concentrated magnetic areas “sunspots” form, where they form, so one cannot predict what will happen next. The comment that the visible portion of the solar magnetic cycle has increased would imply that the sun is warmer. Why?

    Perhaps the scientific questions will be answered due to new information related to the cycle 24 changes.

  46. 96
    BJ_Chippindale says:

    At first I thought perhaps this would simply mean some form of delay in the application of the 11 year cycle and so the “wrong sign” could be made to make sense in terms of the correlation between solar and temperature that is generally observed… but I see that “maunder minimum” bit and all bets are off. I am very glad that that satellite is up there and that the questions are getting asked. Now all I need is the patience to wait for actual answers.

    …and a way to explain to the ignoranti that this doesn’t throw all the rest of what we know into the scrap heap… as they are already claiming.



  47. 97
    Michael Doliner says:

    This is slightly off topic but I don’t understand how anyone can doubt climate change due to greenhouse gases after having read Plass’s article from 1956. You referenced it some time ago and it can be found here:

    Variation in carbon levels is the only explanation for ice ages that has anything like the proper time frame. Solar variation is far too short a cycle.

  48. 98
    Jim Ryan says:

    Deranged Melanie Philips is at it again – see spectator extract further below – but could anyone share some insight into the physicist Harold Lewis. It won’t surprise you that he is not a climate scientist? For such a ‘distinguished’ scientist there appears to be very little about him at the University of California, Santa Barbara website; he hasn’t even got a wiki entry. He appears to be a nuclear engineer with a handful of publications in less than outstanding journals.

    ‘Decency fights back’
    Straws in the wind, maybe, but in the last few days there have been heartening signs of people making a stand for truth, decency and integrity. The first was the resignation from the American Physical Society of Hal Lewis, Emeritus Professor of Physics at the University of California and a scientist of distinction, in protest at the attempt by the APS to shut down debate about its endorsement of anthropogenic global warming. It is a magisterial rebuke which stands witness to the devastating corruption of science represented by the AGW scam. Here’s a sample of Prof Lewis’s resignation letter:

    It is of course, the global warming scam, with the (literally) trillions of dollars driving it, that has corrupted so many scientists, and has carried APS before it like a rogue wave. It is the greatest and most successful pseudoscientific fraud I have seen in my long life as a physicist. Anyone who has the faintest doubt that this is so should force himself to read the ClimateGate documents, which lay it bare. (Montford’s book organizes the facts very well.) I don’t believe that any real physicist, nay scientist, can read that stuff without revulsion. I would almost make that revulsion a definition of the word scientist.

    So what has the APS, as an organization, done in the face of this challenge? It has accepted the corruption as the norm, and gone along with it….

    Do read it all.

  49. 99
    Ray Ladbury says:

    Ryan says, “Do read it all.”

    I’d rather chew broken glass.

  50. 100
    Hank Roberts says:

    For Jim Ryan, the Lewis resignation letter has been covered (as a digression) in several comments in the Cuccinelli thread. Short answer: emeritus.