November through March of 1997-98 and 2015-16 were analyzed using daily Climate Forecast System Reanalysis (CFSR) anomaly data for sea level pressure, SSTs, surface wind, latent and sensible heat flux, sea level pressure, and 500mb geopotential height. The daily SST tendency was calculated throughout both seasons, since forcings affect the SST tendency directly.
Using a threshold of one standard deviation below the average daily SST tendency over both seasons, composites of the above variables were analyzed for days meeting this criterion. SST tendency had a particularly high dependency on latent heat flux. The days included in the composites accounted for 125.17% of the cooling that occurred over the 1997-98 season, whereas 69.82% of the cooling over the 2015-16 season occurred during days included in the composite, highlighting differences between ENSO events.