Highlights – September 2011
conditions strengthened during September 2011 as sea surface temperature
anomalies were below -0.5°C across much of the eastern and central equatorial
Pacific Ocean (Fig. T18, Table T2). The
latest monthly Niño indices were -0.7°C for the Niño 3.4 region and -0.6°C for
the Niño 1+2 region (Table T2, Fig. T5).
Consistent with these conditions, the oceanic thermocline (measured by the
depth of the 20°C isotherm) remained shallower
than average in the east-central equatorial Pacific (Figs. T15 and T16), where
corresponding sub-surface temperatures were 1-3°C below average (Fig. T17).
September, the equatorial low-level easterly trade winds and upper-level
westerly winds remained stronger than average over the central equatorial
Pacific (Table T1,
Figs. T20 and
T21). Convection remained enhanced over western
equatorial Pacific and suppressed near the Date Line and south of the Equator (Figs. T25 and
Collectively, these oceanic and atmospheric anomalies reflect a strengthening
of La Niña conditions that developed during August.
For the latest status of the ENSO
cycle see the ENSO Diagnostic Discussion at: