Guest post by Guillermo Gonzalez
I recently happened upon the SORCE/TIM website and decided to look up the plot of the full total solar irradiance (TSI) dataset (http://lasp.colorado.edu/sorce/data/tsi_data.htm#plots)
The SORCE mission began collecting TSI data in February 2003.
I was curious to see if the variations in the TSI had begun to rise yet, perhaps indicating a start to cycle 24. Visual inspection of the SORCE TSI plot showed just the opposite – variations continue to decline in amplitude. If cycle 24 has started, there are no signs of it in these data.
We can be a bit more quantitative if we examine, instead, a plot of TSI variance with time. I produced such a plot using the daily average TSI data provided on the SORCE web site.
The red data are variance values calculated at two-week intervals. The blue curve is the smoothed data calculated in the same way as smoothed sunspot numbers (basically a 12-month running average). Note, the vertical axis is plotted on a logarithmic scale.
To compare the recent TSI variance trend with the previous sunspot minimum, I looked up the ACRIM2 daily average TSI data at: http://www.acrim.com/Data%20Products.htm
These data are plotted on the same scale as the SORCE data. The smoothed data show a minimum TSI variance near the beginning of 1996, some months before sunspot minimum (October 1996). Notice that the minimum value for the variance during the 1996 minimum was about an order of magnitude larger than the present TSI variance.
The SORCE web site quotes long-term 1-sigma precision (relative accuracy) of their TSI measurements to be 0.001%/yr. This corresponds to a variance of 2 ´ 10-4 W2 m-4. However, the precision should be considerably better than this on the 2-week timescale that I selected for calculating the variance. Unfortunately, I have not been able to locate a quote for the estimated precision of the ACRIM2 measurements. It would be worthwhile to know if the minimum TSI variance of the previous sunspot minimum measured by ACRIM2needs to be corrected for the instrumental precision.
Guillermo Gonzalez writes on his background:
I’m an astronomer, though my present title is associate professor of physics at Grove City College, PA. I wrote a paper (in Solar Physics) with Ken Schatten back in 1987 on predicting the next solar maximum with geomagnetic indices. That was my only contribution on anything having to do with the Sun-Earth connection, but I also got a letter published in Physics Today in 1997 wherein I urged readers to takethe Sun-Earth climate connection more seriously.
These days most of my research is on extrasolar planets.
UPDATE: I received a suggestion for an overlay via email from Terry Dunleavy and I’ve worked one up below. This was done graphically. I took great care to get the two lined up correctly. Note however that the datasets span different lengths of time, as you can note on the two timescales I’ve included on the combined graph. The vertical scale matches exactly between graphs though. – Anthony
UPDATE2: Here is another graphical comparison of the two TSI variance graphs, scaled to have a matching X-axis and appropriately aligned side by side. – Anthony
Leif Svalgaard (11:21:47) :
Thank you so much.
Paul Vaughan (11:51:06) :
Error in the record:
At (16:27:02) Leif Svalgaard quotes Leif Svalgaard (15:14:44) as saying:
“People can agree to disagree respectfully”
No, you have not picked up on the convention used. The first level quote is done simply by using italics, like in above.
If within the italics, there are further quotation marks they mean that they enclose a further quote (that I was quoting someone else – in casu you). So, no error, and no [silly] correction needed.
–
I would add:
They can also choose to do so efficiently.
(Freedom is practical.)
This makes no sense (and for clarity: I do not wish to debate this).
Leif Svalgaard (14:42:52) :
“[…] the convention used […]”
Some of the sloppy quotation ‘conventions’ obfuscate the record. Sometimes the obfuscation appears deliberate (and for clarity: no specific accusation is being made).
– –
Leif: “This makes no sense […]”
I disagree —- & I both respect and concur with your wish to not debate this.
–
In this instance, we have efficiently both agreed & disagreed respectfully.
I tentatively interpret this as a positive sign.
Paul Vaughan (15:28:09) :
Some of the sloppy quotation ‘conventions’ obfuscate the record. Sometimes the obfuscation appears deliberate (and for clarity: no specific accusation is being made).
My convention [and what else is important when discussing my postings?] are not sloppy, but extremely consistent, to the very best of my ability. About the accusations: you cannot have it both ways.
I tentatively interpret this as a positive sign.<
I don’t think anybody is interested in what you consider positive. I’m not, for one.
Re: Leif Svalgaard (19:17:34)
Few of the quoting conventions I see are unambiguous for a casual reader, who might, for example, find this thread via Google search and have no idea what Leif Svalgaard’s quoting convention is. (This is not a complaint – just an observation.)
Paul Vaughan (23:07:50) :
a casual reader,
You are not a casual reader, and furthermore, you knew the context, and you make the assumption that anybody cares about who said what.
I wonder how many scientists read this blog.
And I wonder how many decent scientists choose to not participate because:
1.
There is no mechanism to ensure that it will be respected if they announce that they want to drop a volley with another commenter (who they may perceive as hostile, severely biased, narrowly linear, or politically motivated, for example).
2.
There is no mechanism to prevent other commenters from projecting the false logic that if someone exits a volley, they have forfeited. (They may simply be sensibly steering clear of wasting their time in an exchange with someone who is ideologically entrenched, for example.)
3.
Ad hominem attacks are allowed (and obviously this promotes flame-exchanges).
I am inspired to think of ways to help WUWT pull in truck-loads of money so that moderators can be paid TOP coin to ENFORCE decent standards of conduct.
My theory is that a little gentrification of the online climate discussion would increase by an order of magnitude or more the number of decent scientists willing to comment and share their valuable knowledge.
Paul Vaughan (13:40:34) :
And I wonder how many decent scientists choose to not participate because…
It is normal and decent scientific behavior that if a challenge is issued, the scientist challenged gets to know what the challenge is and gets a forum to rebut the challenge. In the usual Journals there are rather strict rules for how this should play out: you can submit a ‘comment’ [usually negative] on a published paper, to which the scientist being challenged has a right to rebut with a ‘reply’. The ‘comment’ and ‘reply’ will then be published back-to-back…
Paul Vaughan (13:40:34) :
And I wonder how many decent scientists choose to not participate because…
as opposed to indecent scientists?