Niņa conditions developed during August 2011 as sea surface temperatures were
below-average across much of the eastern equatorial Pacific Ocean
The latest monthly Niņo indices were -0.6°C for the Niņo
3.4 region and 0.0°C for the Niņo
1+2 region (Table T2,
Consistent with these conditions, the oceanic thermocline (measured by
the depth of the 20°C
isotherm) was shallower than average in the east-central equatorial Pacific (Figs.
T16). The corresponding sub-surface
temperatures were 1-3°C below average in the east-central equatorial Pacific (Fig.
atmospheric circulation patterns during August continued to show some weak La Niņa
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),
while convection remained enhanced over western equatorial Pacific and
suppressed near the Date Line and south of the Equator (Figs.
T25 and E3).
Collectively, these oceanic and atmospheric anomalies reflect the return of La
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at: