Niņa weakened during February 2011 as the magnitude of the negative sea surface
temperature anomalies decreased across much of the equatorial Pacific Ocean (Fig.
T18, Table T2).
The latest monthly Niņo indices were -1.3°C for the Niņo
3.4 region and +0.1°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) remained slightly shallower than average over the eastern equatorial
Pacific (Figs. T15 and
T16), with sub-surface temperatures
reaching 1°C to 4°C
below average in this region (Fig. T17).
during February, the equatorial low-level easterly trade winds remained stronger
than average over the western and central Pacific (Table
T1, Fig. T20), while convection remained
enhanced over Indonesia and suppressed across the western and central equatorial
Pacific (Figs. T25
and E3). Also, over the
eastern Pacific the low-level cross-equatorial flow and the associated upwelling
were notably weaker during February. Collectively, these oceanic and atmospheric
anomalies reflect a weakening La Niņa.
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at: