La Niņa continued but weakened
during February 2009, as negative sea surface temperature (SST) anomalies
remained below average across the central and east-central equatorial Pacific
The latest monthly SST index was -0.7°C in the Niņo-3.4 region,
and -0.7°C in the Niņo-4 region (Table T2).
The oceanic thermocline along
the equator, measured by the depth of the 20°C
isotherm, remained shallower than average across the eastern half of the
equatorial Pacific during February (Figs. T15, T16).
Consistent with these conditions, subsurface temperatures in the eastern
equatorial Pacific were 2-5oC below average at thermocline depth (Fig.
Enhanced low-level easterly
winds and upper-level westerly winds were present across the equatorial
during February (Figs. T20,
T21). These conditions continued to be associated
with suppressed convection over the central equatorial
and enhanced convection across
This combination of oceanic and atmospheric conditions reflects a weakening La
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at: