I’ve moved to WordPress. This post can now be found at Unheralded Changes in ERSST.v3 Data##############
This’ll be a quick post with only two illustrations.
Back in an August 8 post, My Curse on Data Set Updates, I noted the lack of updates to the ERSST.v3 data. At that time, the data ended in April 2008. The updates resumed last month, but I didn’t think much about it, other than I was pleased that the newer data set had been made current. (I’ll remove that August 8 post in a few days, since both data sets resumed their updates.) Then, in a comment here, Bill Illis noted that he’d read a recent remark at another website about a change in SST data. Yesterday, I noticed a very minor change in the webpage address for the monthly global SST data. There was a “v3b” after the data set name, as in ersstv3b.
The old address for the same data excluded the “v3b”. (The following link no longer functions.)
Did version “B” include the “bucket correction” corrections? Refer to “A large discontinuity in the mid-twentieth century in observed global-mean surface temperature”, by Thompson et al (2008):http://www.nature.com/nature/journal/v453/n7195/abs/nature06982.html
NOPE! It doesn’t include them.
Figure 1 is a comparative graph of the ERSST.v3 (old) and ERSST.v3b (new) versions of the Global SST anomaly data. The data has been smoothed with a 37-month filter. There are very minor changes when viewing the global data set.
Subtracting the ERSST.v3 (old) from the ERSST.v3b (new) data presents a better view of the differences. Globally, the update appears to have created a very minor increase in trend, ~0.022 deg C per Century.
Are the corrections small changes in all oceans or are they major changes in small data sets such as the Arctic and Southern Oceans? The updates aren’t mentioned in the main page of the data set.
We’ll find out in a future post. (I haven’t a clue, but my guess is that the changes are in the high-latitudes of the Southern Hemisphere.)
Thanks to Bill Illis for calling my attention to the update.
…are included in text of post.