There has been concern expressed recently around the blogosphere that NOAA hasn’t updated their weekly El Niño-Southern Oscillation (ENSO) sea surface temperature-based indices webpage since May 16, 2012. I use the NOAA NOMADS website (alternate NOAA computer here) for my sea surface temperature updates so this didn’t present any difficulties for me. It did, however, cause problems for the WattsUpWithThat ENSO meter, since it had been linked to that NOAA SST indices webpage. To remedy that problem, the WUWT ENSO meter is now updated from an Australia Bureau of Meteorology webpage here.
What happened to the NOAA weekly updates?
NOAA changed climatologies (base years for anomalies) from 1971-2000 to 1981-2010 and provided a new webpage, which is currently up to date. The standard climatology for the Reynolds OI.v2 sea surface temperature anomalies continues to be 1971-2000, and that’s what the NOMADS and BOM use. As a result, there will be differences between the anomalies on the NOAA indices webpage and on the NOMADS and BOM webpages. And since the NOAA Oceanic NINO Index (ONI) now uses a sliding series of 5-year climatologies (see here), it won’t agree with any of them.
Through a link on their Monthly Atmospheric & SST Indices webpage, NOAA explains the reason for the change in base years on a webpage titled Climate Diagnostics Bulletin Updates to Climatologies and Indices Beginning with January 2011 Data:
Beginning with the January 2011 monthly data, all climatologies, anomalies, and indices presented within and related to the monthly Climate Diagnostics Bulletin will be updated according to current WMO standards. For datasets that span at least the past 30 years (such as atmospheric winds and pressure), the new anomalies will be based on the most recent 30-year climatology period 1981-2010.
Well, there it is.
For those monitoring the weekly NOAA ENSO SST indices webpage, don’t forget to update your favorites with the new webpage.