With the current El Niño possibly peaking now it will be interesting to see when the satellite derived global temperature anomalies peak. If past history during the satellite era is any indication, the satellite indicated global lower tropospheric temperature anomaly could peak as much as 3 to 6 months after the El Niño Southern Oscillation (ENSO) peak. The latest monthly Multivariate ENSO Index (MEI) from the US National Oceanic and Atmospheric Administration (NOAA) indicates a slight downturn in the MEI for October compared to September, which could possibly indicate the peak was in September. However, we will have to wait another month or two to be more confident. If the peak was in September, this El Niño will rank as the third most intense of the satellite era based on the MEI, after the 1997-98 and 1982-83 events.
The University of Alabama at Huntsville (UAH) satellite derived monthly global temperature for the lower troposphere (TLT) anomaly estimates showed a sharp rise from September to October as shown with the MEI in Figure 1. Also shown are the Mauna Loa apparent sunlight transmission monthly averages to indicate significant volcanic effects on sunlight transmission through the atmosphere. Effects from reduced sunlight transmission are evident after the El Chichón and Pinatubo volcanic eruptions in April 1982 and June 1991 respectively, after which sharp drops can be seen in the TLT anomaly estimates. Most of the strongest El Niños have been followed by La Niñas with corresponding drops in TLT for as much as a year or two following.
For the latest monthly ENSO updates, see the ENSO page accessible from the menu bar at the top of this post.