From NASA’s website (h/t to David Archibald)
By Adam Voiland
NASA’s Earth Science News Team
Two satellite instruments aboard NASA’s Solar Radiation & Climate Experiment (SORCE) mission — the Total Solar Irradiance Monitor (TIM) and the Solar Irradiance Monitor (SIM) — have made daily measurements of the sun’s brightness since 2003.
The two instruments are part of an ongoing effort to monitor variations in solar output that could affect Earth’s climate. Both instruments measure aspects of the sun’s irradiance, the intensity of the radiation striking the top of the atmosphere.
Instruments similar to TIM have made daily irradiance measurements of the entire solar spectrum for more than three decades, but the SIM instrument is the first to monitor the daily activity of certain parts of the spectrum, a measurement scientists call solar spectral irradiance.
In recent years, SIM has collected data that suggest the sun’s brightness may vary in entirely unexpected ways. If the SIM’s spectral irradiance measurements are validated and proven accurate over time, then certain parts of Earth’s atmosphere may receive surprisingly large doses of solar radiation even during lulls in solar activity.
“We have never had a reason until now to believe that parts of the spectrum may vary out of phase with the solar cycle, but now we have started to model that possibility because of the SIM results,” said Robert Cahalan, the project scientist for SORCE and the head of the climate and radiation branch at NASA’s Goddard Space Flight Center in Greenbelt, Md.
Cahalan, as well as groups of scientists from the University of Colorado at Boulder and Johns Hopkins University, presented research at the American Geophysical Union meeting in San Francisco in December that explored the climate implications of the recent SIM measurements.
Cahalan’s modeling, for example, suggests that the sun may underlie variations in stratospheric temperature more strongly than currently thought. Measurements have shown that stratospheric temperatures vary by about 1 °C (1.8 °F) over the course of a solar cycle, and Cahalan has demonstrated that inputting SIM’s measurements of spectral irradiance into a climate model produces variations of that same magnitude.
Without inclusion of SIM data, the model produces stratospheric temperature variations only about a fifth as strong as would be needed to explain observed stratospheric temperature variations. “We may have a lot more to learn about how solar variability works, and how the sun might influence our climate,” Cahalan said.
Measuring Variation
As recently as the 1970s, scientists assumed that the sun’s irradiance was unchanging; the amount of energy it expels was even called the “solar constant.” However, instruments similar to TIM and SIM have made clear that the sun’s output actually fluctuates in sync with changes in the sun’s magnetic field.
Indeed, TIM and its predecessor instruments, whose records of irradiance began in 1978, show that the sun’s output varies by about 0.1 percent as the sun cycles through periods of high and low electromagnetic activity every eleven years or so. In practice, this cycling means the sun’s brightness, as measured by TIM, goes up a bit when large numbers of sunspots and accompanying bright spots called faculae are present on the sun, yet goes down slightly when sunspots and faculae are sparse, like they have been in the last few years as the sun has gone through an unusually quiet period.
However, there is a critical difference between the SIM and TIM, explains Jerry Harder, the lead SIM instrument scientist and a researcher at the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado in Boulder. While the TIM lumps all wavelengths — including infrared, visible, and ultraviolet light — into one overall measurement, the SIM isolates and monitors specific portions of the spectrum.
Notably, this makes SIM the first space-based instrument capable of continuously monitoring the visible and near-infrared portion, parts of the spectrum that are particularly important for the climate. SIM also offers the most comprehensive view of the individual components that make up the sun’s total solar irradiance to date.
Some of the variations that SIM has measured in the last few years do not mesh with what most scientists expected. Climatologists have generally thought that the various part of the spectrum would vary in lockstep with changes in total solar irradiance.
However, SIM suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did — while irradiance in certain visible and infrared wavelengths surprisingly increased, even as solar activity wound down overall.
The steep decrease in the ultraviolet, coupled with the increase in the visible and infrared, does even out to about the same total irradiance change as measured by the TIM during that period, according to the SIM measurements.
The stratosphere absorbs most of the shorter wavelengths of ultraviolet light, but some of the longest ultraviolet rays (UV-A), as well as much of the visible and infrared portions of the spectrum, directly heat Earth’s lower atmosphere and can have a significant impact on the climate.
Climate Consequences?
Some climatologists, including Judith Lean of the United States Naval Research Laboratory, Washington, remain skeptical of the SORCE SIM measurements. “I strongly suspect the SIM trends are instrumental, not solar,” said Lean, noting that instrumental drift has been present in every instrument that has tracked ultraviolet wavelengths to date.
“If these SIM measurements indicate real solar variations, then it would mean you could expect a warmer surface during periods of low solar activity, the opposite of what climate models currently assume,” said Gavin Schmidt, a climate modeling specialist at NASA’s Goddard Institute for Space Studies in New York City.
It would also imply that the sun’s contribution to climate change over the last century or so might be even smaller than currently thought, suggesting that the human contribution to climate change may in turn be even larger than current estimates.
However, the surprising SIM measurements correspond with a period of unusually long and quiescent solar minimum that extended over 2007 to 2009. It may not be representative of past or future solar cycles, solar scientists caution.
Researchers will surely continue puzzling over the surprising SIM results for some time, but there is already considerable agreement on one point: that the need for continuous SIM and TIM measurements going forward has grown more urgent.
Modeling studies are showing that our climate depends critically on the true solar spectral variations. “If we don’t have the instruments up there to watch this closely, we could be arguing about spectral irradiance and climate for decades,” said Cahalan.
A new TIM instrument is slated to launch on the Glory satellite this February, but a replacement for the SORCE SIM instrument — called the Total and Spectral Solar Irradiance Sensor (TSIS) — likely won’t fly until 2014 or 2015. This could create a gap between the current SIM and its replacement, a situation that would present a significant obstacle to identifying any possible longer-term trend in solar spectral irradiances, and thus to nailing down the sun’s role in long-term climate change.
“Both instruments — TIM and SIM — are absolutely critical for understanding how climate works. We neglect either of them at our peril,” said Cahalan.
Solar activity – including sunspots and accompanying bright areas called faculae – vary over the course of a solar cycle and affect solar irradiance. Credit: NASA
Related Links:
SORCE Website
http://lasp.colorado.edu/sorce/index.htm
AGU Session: Solar Variability and Climate
http://www.agu.org/cgi-bin/sessions5?meeting=fm10∂=GC13E&maxhits=400
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Additional information:
Leif Svalgaard writes in email:
This is legit.
It is a confusing graph. It shows how much the spectral emission has
changed between 2004 and 2007. Since solar activity was decreasing one
expected UV to decrease. Instead it increased. The increase was offset
by a decrease in IR, leaving TSI almost constant. That the near UV
goes up when solar activity goes down I pointed out some time ago
[before the LASP people noticed it], see the lower two panels of
http://www.leif.org/research/Erl70.png (provided below)
There are all kinds of ramifications, see the talks in Session 4 at:
http://lasp.colorado.edu/sorce/news/2010ScienceMeeting/agendas.html#speakers
I agree with Leif that the plot is confusing. It is a difference plot, and one would like to know the percentage changes of UV radiation as compared to some kind of average.
Is this a 1% effect, or is it a 10% effect or even more?
The two instruments, SIM and SOLSTICE, differ by a factor two and more in the range where they overlap. This is called “compare well”. One could also conclude that the error bars exceed +- 50% of the difference plot values. So, it could indeed be instrumental problems first.
This was precisely what I’ve suspected.
“If these SIM measurements indicate real solar variations, then it would mean you could expect a warmer surface during periods of low solar activity, the opposite of what climate models currently assume,” ………..said Gavin Schmidt
Precisely. El Nino, anyone?
So then, as I understand it the thrust of this article basically suggests that we don’t know it all yet. Indeed much more research is needed before we can fully understand the behaviour of the sun and how its subtle changes might influence earth and its climate. A position at odds with the dogmatic view that the science is settled, whereas in fact all that has been decided is the politics. The latter point going some way towards explaining the true motivations of Messers Mann, Jones and others who have become politicised beings rather than genuine open minded scientists.
I have benefited immensely from following the dialogue on this blog over past months, it is a pleasure to wish Anthony, all guest contributers and respondents the very best of Christmas’s, may you all find joy in the New Year.
NASA now reckon that global warming is going to take the edge off the next ice age. But remember, CO2 still drives the climate, but only when there are no other “natural variations” to “overpower” it.
“Earth’s orbit around and orientation toward the Sun change over spans of many thousands of years. In turn, these changing “orbital mechanics” force climate to change because they change where and how much sunlight reaches Earth. (Please see for more details.) Thus, changing Earth’s exposure to sunlight forces climate to change. According to scientists’ models of Earth’s orbit and orientation toward the Sun indicate that our world should be just beginning to enter a new period of cooling — perhaps the next ice age.
However, a new force for change has arisen: humans. After the industrial revolution, humans introduced increasing amounts of greenhouse gases into the atmosphere, and changed the surface of the landscape to an extent great enough to influence climate on local and global scales. By driving up carbon dioxide levels in the atmosphere (by about 30 percent), humans have increased its capacity to trap warmth near the surface.”
http://science.nasa.gov/earth-science/big-questions/what-are-the-primary-causes-of-the-earth-system-variability/
It seems that over the same period 2004 to 2007 ozone quantities above 45km increased but below 45km they decreased.
Would anyone care to comment since ozone trends (and thus temperatures) are supposed to be linked to solar variability especially in the stratosphere ?
I think the issue of stratospheric temperature trends is critical because that is what dictates pressure distribution in the troposphere.
Furthermore there is nothing different now from what was observed in the MWP (active sun and poleward/zonal jets) in the LIA (quiet sun and equatorward/meridional jets) in the late 20th century (active sun and poleward/zonal jets) and today (quiet sun and equatorward/meridional jets).
Thus, resolve this issue to discredit AGW completely and perhaps also overturn previous assumptions about the effect of CFCs.
I think we will find that a cooling stratosphere at a time of active sun and a warming stratosphere at a time of quiet sun are entirely natural phenomena.
It has to be so otherwise jets could not go more poleward when the sun is more active. That requires a cooling stratosphere for a more positive polar vortex. A warming stratosphere ( netted out globally not just at the equator) must always send the jets equatorward yet we do not see a warming stratosphere unless the sun is quiet.
We are getting close now and the change in solar behaviour is the best thing that could have happened for climate diagnostics.
Color me confused with this…..
“If these SIM measurements indicate real solar variations, then it would mean you could expect a warmer surface during periods of low solar activity, the opposite of what climate models currently assume,” said Gavin Schmidt, a climate modeling specialist at NASA’s Goddard Institute for Space Studies in New York City.
It would also imply that the sun’s contribution to climate change over the last century or so might be even smaller than currently thought, suggesting that the human contribution to climate change may in turn be even larger than current estimates.
If the SIM measurements were correct thus the assumptions installed in the models incorrect then the affect attributed to those assumptions would need be attributed to another influence. Hence indication would be something is going on which we do not understand (nothing new about that) and therefore a leap to suggestion of greater human contribution on the other side of the coin is nothing but simple unfounded rhetoric / propaganda stream.
Dear Lee,
No. You Are not confused at all. You just need to learn how the RC reasoning works. Every grain of new knowledge, no matter how poorly understood, always points to AGW being “worse than we thought. By next year they will have models predicting that the globe exploded from heat shock five years ago.
Am I the only person to see that Gavin Schmidt’s response is a non sequitur to the data presented?
“If these SIM measurements indicate real solar variations, then it would mean you could expect a warmer surface during periods of low solar activity, the opposite of what climate models currently assume,” said Gavin Schmidt”
A greater amount of energy reaching the surface in some wavelengths most likely does not affect the climate at all because what matters most for climate is the amount of energy that gets into the oceans.
If ozone changes in the atmosphere alter the tropospheric pressure distribution for a change in total cloudiness and albedo as seems to be the case then that would dwarf everything else by regulating the amount of energy that the oceans receive and absorb.
I thought that the hypothesised solar influence was not irradiance, but solar magnetic activity. So whatever Schmidt says about irradiance is not really the point, although in combination with other changes it would obviously make a difference.
Can anyone correct me here?
If Gavin Schmidt’s quote is legit, it’s interesting only in that he used “assume. That may be the most accurate statement of climatology yet to issue from NASA.
Schmidt’s comment is as useful as a chocolate fireguard and just a defensible!
but, then again, what can one expect from the keepers of the faith!
John,
My thinking exactly. If a, then b. B is AGW, and is truer than true no matter what. Confirming this leads all antecedents to be true as they can always lead to AGW – which is true. It’s a fortress!!!
Eureka! As I always suspected, the Lipshitz factor dwarfs the Aardvargeon constant, leaving the Jimjam variable in a state of random flux. Stop the presses!
More evidence that hindcasting by the modellers must incorporate fudge factors to fit results to the data. No wonder the models diverge from reality going forward.
What bearing does the data coming from EVE on SDO have on this?
http://www.nasa.gov/mission_pages/sdo/science/Solar%20Irradiance.html
http://lasp.colorado.edu/eve/science/eve_science.htm
http://lasp.colorado.edu/eve/docs/EVE_Overview_SolarPhys.pdf
Deja Vu? We don’t really know what effect element A (Sun) has on element B (climate), but we know for a fact that element C (CO2) overpowers element A! QED.
Robinson says:
December 22, 2010 at 2:43 am
(A) TSI is ‘assumed’ constant so some folks say there is no impact on climate.
(B) There is also the hypothesis that cosmic rays influence cloud formation (Svenmark). The solar magnetic field variations can impact how many cosmic rays hit the earth.
This data is showing that TSI may not be constant (who’d a thunk it?!).
If I were a betting girl, I’d say there is something in both but early days still.
Under the graph is written: “Between 2004 and 2007, the Solar Irradiance Monitor (blue line) measured a decrease in ultraviolet radiation (less than 400 nanometers) that was a factor of four to six larger than expected (black line).
Leif Svalgaard comments at the end of the article:
“This is legit. It is a confusing graph. It shows how much the spectral emission has
changed between 2004 and 2007. Since solar activity was decreasing one
expected UV to decrease. Instead it increased.”
Did UV decrease or increase?
We still don’t know how UV will develop come a long Dalton-like minimum as we haven’t experienced one since inventing these instruments. Is there a possibility that it follows the visible radiation with a time lag, so both visible and UV radiation go down during a grand minimum?
Robin is right, I can’t reconcile Leif’s comment with the graph. I also don’t understand why a decrease in the shortest UV wavelengths would increase Stratospheric warming or O3 quantities above 45km. Stephen Wilde, I think hits the nail on the head, but I don’t understand the mechanism in the upper stratosphere. Can you explain Stephen?
Climate model assumptions might be wrong? Ya think? What are the odds?
If solar fluctuations have an impact on climate, what are world governments going to do to control that? Who can they tax and what can they legislate? How about turning on and off the CO2 pump to compensate? /sarc
What about longer and shorter wavelengths, do they have no effect at all?
We cook with Microwave ovens everyday…..A microwave oven works by passing non-ionizing microwave radiation, usually at a frequency of 2.45 gigahertz (GHz)—a wavelength of 122 millimetres (4.80 in)
http://en.wikipedia.org/wiki/Microwave_oven
…and what about Induction and other phenomena?. The world it is only what we can see with our eyes (around 500 nm).
Excuse me, I am just the “Fool on the Hill” just watching the world spinning around.
“If these SIM measurements indicate real solar variations, then it would mean you could expect a warmer surface during periods of low solar activity, the opposite of what climate models currently assume,” said Gavin Schmidt, a climate modeling specialist at NASA’s Goddard Institute for Space Studies in New York City.
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Ah, applying the new scientific method of Climatology, “If observed data conflicts with model output (theory), then the observed data must be in error somehow because the theory has to be right – the model output says so.”
It’s my understanding that only very recently climate models have incorporate “top-down” solar processes. Most only include TSI as the solar variable. It seems strange that Gavin Schmidt could make any statement regarding model outputs and these new UV measurements.
I’m basing what I say on what I got from this review
http://www.agci.org/dB/PDFs/10S1_LGray_SolarInfluencesCLimate.pdf