Optimally Interpolated SST (OI.v2 SST) versus Extended Reconstructed SST (ERSST.v2) Data

INTRODUCTION

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.
ftp://ftp.emc.ncep.noaa.gov/cmb/sst/papers/oiv2pap

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.
http://i34.tinypic.com/2lka2w2.jpg
Arctic Ocean SST Anomalies (65 to 90N)
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http://i34.tinypic.com/2rzc94x.jpg
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.
http://i35.tinypic.com/2hplgts.jpg
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.
http://i33.tinypic.com/11tlbwz.jpg
Northern Hemisphere SST Anomalies
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http://i35.tinypic.com/23i9bna.jpg
Southern Hemisphere SST Anomalies
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http://i37.tinypic.com/2uiueqo.jpg
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.
http://i35.tinypic.com/noyb6x.jpg
North Atlantic SST Anomalies (0 to 75N, 78W to 10E)
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http://i34.tinypic.com/144483r.jpg
South Atlantic SST Anomalies (0 to 60S, 70W to 20E)
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http://i34.tinypic.com/2m3pj4m.jpg
North Pacific SST Anomalies (0 to 65N, 90 to 180W) & (0 to 65N, 100 to 180E)
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http://i34.tinypic.com/15qar29.jpg
South Pacific SST Anomalies (0 to 60S, 70 to 180W) & (0 to 60S, 145 to 180E)
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http://i33.tinypic.com/53smqs.jpg
Indian Ocean SST Anomalies (30N to 60S, 20 to 145E)
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SOURCE

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).
http://nomads.ncdc.noaa.gov/#climatencdc