One of the big problems of climate science is uncertainty. Some things that always seem to be in flux are historical datasets, partly because, well, they have so much inherent uncertainty built in. Such is the case of the Historical TSI plot presented on the University of Colorado SORCE web page. All of the sudden, with little fanfare, it changed, and not just a little. What is interesting are the drops during the Maunder Minimum as well as our current Solar Cycle 24

Readers may know that a controversy persists as to the actual TSI behavior in the late 80s/early 90s. The so called “ACRIM gap” was created when the Challenger shuttle was destroyed in a famous accident due to mismanagement combined with launch pressure. It caused by the delay of the shuttle-launched ACRIM2, a satellite that was to maintain continuity of TSI measurements. The debate over how to bridge the gap is relevant to the explanation of the warming that persisted into the 90s. The debate has been quite heated, with those invested in the IPCC forcing story claiming that the TSI decreased in the 90s and those (Willson and Scafetta) who argued that the TSI continued to increase in the 90s.

Some previous TSI reconstructions:

Now there’s even more tinkering from SORCE:

http://lasp.colorado.edu/home/sorce/data/tsi-data/#plots

The SORCE TSI reconstruction looked like this a month ago (word BEFORE added):

Here is what it looks like as of today (word AFTER added):

They say this about it today:

This historical reconstruction of TSI is based on that used in the IPCC AR5 Working Group’s Assessment Report and based on TSI reconstructions by Krivova et al. (JGR 2010) and Ball et al. (A&A, 2012). The values from their SATIRE model have been offset -0.30 W/m2 to match the SORCE/TIM measurements during years of overlap and then extended using SORCE/TIM annual averages from 2003 onward. The historical reconstruction provided here was computed by G. Kopp using TIM V.15 data in February 2014, and is updated annually as new TIM data are available. Download the ASCII data file Explore the data interactively with LISIRD

Since the previous dataset wasn’t available to me to plot to show differences and comparisons, here is an overlay of the 2013 and 2014 image versions of the plot, scaled to fit properly since the Y axis changed in 2014 to accommodate the greater range:

They have changed the last three solar maxima and now show a clear roll-off since about 1975. Those are enormous changes since last year’s dataset.

Of note is the drop of about 0.3 w/sqm during the last minimum. You’d think they have a measurement handle on that with our current satellite platform, so you have to wonder why that would need adjustment.

Also of note is a drop of about 0.2w/sqm during the Maunder Minimum.

Not only is global temperature adjusted and is a constantly moving target, now so it is with solar irradiance. With so much input data in flux, the “uncertainty monster” of climate modeling output keeps growing.

h/t to Gordon Fulks and Aaron Smith

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