Readers may recall a story on WUWT from April titled: Solar Dynamics Observatory – STUNNING first images and movies
Now, SDO imagery of the sun is online. This week spaceweather.com has started using SDO sunspot imagery in place of the familiar SOHO MDI image on their left sidebar. See all resolutions: 4096, 1024, 256 The upside of the 4096 pixel image is that the detail is striking, the downside is that even tiny sunspecks are now visible in exquisite detail.
The real question now is; what will this new detail do to sunspot counts. As we saw in August 2008, when SIDC retroactively counted a sunspeck to snatch away a spotless month, will the SDO now be the new speckometer? Older telescopes and projection methods would never have seen the sunspecks we see today.
As we see with Geoff Sharp’s Layman’s Sunspot Count, both SIDC and NOAA’s counts are higher than the layman’s count. Now with SDO imagery, will even more miniscule sunspecks widen the gap between them? See the graph below comparing SIDC, NOAA, and LSC:
From Geoff Sharp’s website, here’s how the new Layman’s count works:
THE LAYMAN’S COUNT METHOD & HISTORY
There has been a lot of comments recently about the tiny specks that have been counted as sunspots. A tiny speck can get a daily count of 11 which severely skews the record. Also I have noticed on the SIDC record some days where the Sun is completely blank but the records show a sunspot count. NOAA is another magnitude higher than the SIDC, NOAA using a different method not meant to compare with the historical count. During times of high speck count we need a new standard to record sunspots that gives us a realistic measure of today’s activity verses the last Grand Minimum.
Robert Bateman a very motivated amateur solar enthusiast and myself started a thread at www.solarcycle24.com (which has unfortunately developed into an anti Landscheidt, Pro AGW forum) and soon devised a plan to come up with a reliable standard. We would use the existing SOHO 1024 x 1024 Continuum images and measure the pixels involved in a Sunspot. Initially it had to be determined what a standard sunspot should represent in size and density, to try and represent a minimum counter like Wolf may have done 200 years ago. After some deliberation and advise from Robert who also dabbles in Astronomy with his own equipment, we came up with a minimum standard.
To be counted, a sunspot or group must have 23 pixels which have a reading in the green channel of 0-70 for at least 24 hours.
All pixels in a digital image have a RGB reading which split out into separate Red, Blue, Green channels and can be easily measured and counted in one action using a freeware graphics program called GIMP.
So the standard was set, which now enabled us to go back over the records and weed out the offending specks and blank days.
The official Layman’s Sunspot Count is compared against the SIDC record which is considered conservative when compared with other institutions involved. Basically we use the same sunspot number as SIDC but replace them with zero on days that don’t make the grade. When the SIDC count is made up of two or more areas and if any of the area’s do not make the Layman’s Count, the overall SIDC daily count will be reduced by the areas that fail. Spots that count 23 pixels and over before midnight and then continue on to pass the 24 hour rule will take the SIDC value of that day. Existing Spots that have made the grade but measure less than 23 pixels at midnight are not counted on the next day.
Unless solar science comes up with a way to deal with the advances in technology and properly merge it into the older human-optical record, the sunspot record will start looking like the surface temperature record, with upwards trends due to adjustments (or lack thereof).
I think Sharp and Bateman are on to something, and if you’ll provide me a graphic that isn’t drop shadowed onto a dark background, I’ll add it to the upcoming WUWT solar page with a link to yours. – Anthony