I would prefer to use ERSST.v3 in all posts since it’s the most up-to-date version of SST data, but I have yet to find a simple way to download time-series data for it. For short-term data, however, monthly Optimally Interpolated SST (OI.v2 SST) data is available from NOMADS from November 1981 to present. The OI.v2 SST data provides better resolution than ERSST.v2, but it’s obviously not a long-term data set. The improvements are discussed in the Reynolds et al paper (2002) “An Improved In Situ and Satellite SST Analysis for Climate”, Journal of Climate, 15, 1609-1625.
This post provides a visual comparison of OI.v2 SST and ERSST.v2 SST data for the period that the two data sets overlap, November 1981 to present. As you will note, the OI.v2 SST data illustrates more detail for the Southern Hemisphere and the extreme high latitudes. For this reason, I’ve elected to use it as the source for future monthly SST updates.
THE DATA SETS WITH THE GREATEST DIFFERENCES
As noted above, the differences between OI.v2 and ERSST.v2 SST data for the Arctic and the Southern Ocean are significant. They are illustrated in the following two graphs. Note the spike in the 2007 Arctic Ocean SST anomalies. I’ll do a follow-up post on that blip to illustrate its primary location.
Arctic Ocean SST Anomalies (65 to 90N)
Southern Ocean SST Anomalies (60 to 90S)
NINO3.4 SST ANOMALY
There are no major differences between the two data sets for NINO3.4 SST anomalies.
NINO3.4 SST Anomalies (5S to 5N, 170W to 120W)
HEMISPHERIC AND GLOBAL SST ANOMALIES
There is little difference between the two data sets for the Northern Hemisphere, but there are significant changes in the Southern Hemisphere data. These changes to the Southern Hemisphere are then reflected in the Global SST anomaly data.
Northern Hemisphere SST Anomalies
Southern Hemisphere SST Anomalies
Global SST Anomalies
OCEAN SST ANOMALY DATA COMPARISONS
The following graphs compare SST anomalies for the Indian Ocean as a whole and for the North and South Atlantic and Pacific Oceans. As noted previously, the Southern Hemisphere data sets have the greater differences.
North Atlantic SST Anomalies (0 to 75N, 78W to 10E)
South Atlantic SST Anomalies (0 to 60S, 70W to 20E)
North Pacific SST Anomalies (0 to 65N, 90 to 180W) & (0 to 65N, 100 to 180E)
South Pacific SST Anomalies (0 to 60S, 70 to 180W) & (0 to 60S, 145 to 180E)
Indian Ocean SST Anomalies (30N to 60S, 20 to 145E)
Smith and Reynolds Extended Reconstructed SST Sea Surface Temperature Data (ERSST.v2) and the Optimally Interpolated Sea Surface Temperature Data (OISST) are available through the NOAA National Operational Model Archive & Distribution System (NOMADS).