Tropical
Highlights - December 2021
During December
2021, sea surface
temperatures (SSTs) were below-average across the
central and eastern equatorial Pacific (Fig.
T18). The latest monthly Niņo indices were -1.5°C for
the Niņo 1+2 region, -1.1°C for the Niņo 3.4 region and -0.9°C for the Niņo 4 region (Fig. T5, Table T2). The depth of
the oceanic thermocline (measured by the depth of the 20°C isotherm) was below-average
across the eastern equatorial Pacific (Figs. T15,
T16). The
corresponding sub-surface temperatures were 1-5°C below-average (Fig. T17).
Also during December, the
lower-level easterly winds and the upper-level westerly winds were above-average
across the east-central and eastern equatorial Pacific (Table T1, Fig. T20, Fig. T21).
Meanwhile, tropical convection was suppressed over the central equatorial
Pacific and enhanced over Indonesia and western equatorial Pacific (Figs. T25, E3). Collectively, these oceanic and
atmospheric anomalies were consistent with La Niņa conditions.
For the latest status of the ENSO
cycle see the ENSO Diagnostic Discussion at:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html