NOAA is now using their new V4 ERSST, and so should I. It has come along at a time where I am preparing my own V3 of TempLS (more below), so I will make a double transition.
But first I should mention an error in my earlier processing of V3b, noted in comments here. ERSST3b came in decade files; that helped, because decades before the present did not change and did not require downloading. So I collected them into a structure, and with each update to the current decade (every month) merged that with the earlier decades.
However, I misaligned them. Most climate data uses the strict decade numbering (1961-90 etc), but ERSST uses 2000-2009. I got this wrong in the earlier data, creating a displacement by 1 year. Fixing this naturally gave better alignment with other datasets.
I'll describe the new TempLS version in detail in coming days. V 2.2 of TempLS had become unwieldy due to accumulation of options and special provisions for circumstances that arose along the way. I have made a new version with simplified controls, and using a simple iterative process described here. It should in principle give exactly the same answers; however I have also slightly modified the way in which I express ERSST as stations.
The new version is an R program of just over 200 lines. Of course, when simplifying there are some things that I miss, and one is the ability to make spherical harmonics plots (coming). So for a while the current reports will lag behind the results tabled above. That table, and the various graphs on the latest temperature page, will now be using ERSST v4.
Below the fold, I'll show just a few comparison results.
I've used running means to smooth out monthly noise, and focussed on the period since 1990. At some stage I might say more on the V4 changes, but that has been covered extensively elsewhere. I show the old results before fixing the missing year problem, then the V3b results after fixing, still using V2.2. Then there are results using new ERSS v4 and new TempLS V3. Ideally I would separate the effects of the new code and new ERSST, but getting V3b working with ERSST v4 would take a while, and the combined effect makes very little change.
So here are the grid weighted results. The effect of the year error is clear, but there is little change going from ERSST 3b and TempLS2.2 to ERSST 4 and TempLS 3.
And here are the grid weighted results, which are similar.