A Note Regarding The NOAA ENSO Meter

There have been a number of comments at WattsUpWithThat wondering if the NOAA ENSO Meter, Figure 1, is broken. The ENSO Meter reading has been at 0.0 deg C for over a month, even though weekly NINO3.4 SST anomalies, based on the NOAA Reynolds OI.v2 Sea Surface Temperature data, has been below the threshold of a La Nina event (-0.5 deg C) for three weeks. Refer to Weekly ENSO Index SST data from NOAA. Those comments questioning the ENSO Meter included my August 22, 2011 at 7:08 am question to Anthony Watts on the La Niña returns thread. There was a reference to the meter again today in the WUWT post It’s official: NOAA’s Climate Prediction Center says La Niña is back.

Figure 1

Leon Brozyna’s August 22, 2011 at 9:12 am comment on the La Niña returns thread suggested the ENSO Meter was based on the NOAA Oceanic NINO Index , also known as ONI. (ONI is the 3-month average of NINO3.4 Sea Surface Temperature anomalies based on the NOAA ERSST.v3b dataset.) Leon’s comment made sense since ONI was the only ENSO index showing a 0.0 deg C anomaly for that period. I wanted to confirm that when the ONI data was updated earlier this week so I could write a post about it, but the ONI reading for the “season” of June-July-August was also 0.0 deg C. The ONI data didn’t change, and the meter didn’t budge, so that was no help. I wrote to Anthony Watts today regarding the ENSO meter, and he had already sought the answer directly from NOAA. NOAA confirmed that the ENSO meter is based on the Oceanic NINO Index.

And that means the ENSO meter will be 0.0 deg C until the ONI data is updated in early October 2011.