Positive sea surface
temperature (SST) anomalies persisted in the central equatorial Pacific
during February 2005. SST
departures decreased throughout the equatorial Pacific east of the date
line, as negative SST anomalies in the eastern equatorial Pacific expanded
westward. Negative SST anomalies
were observed in the Niņo 1+2 (-0.6) and Niņo 3 (-0.2) regions (Fig. T18, Table
T2). The SST anomaly in the Niņo 3.4 region decreased to 0.3
In spite of the recent
cooling trend in the SSTs, the Tahiti-Darwin SOI (Table T1, Fig.
to -4.1 in February, which is the lowest monthly value of the SOI since
February 1983. This is consistent with the patterns of strongly enhanced
convection (Fig. T25) and low-level westerly anomalies (Fig.
that persisted over the central equatorial Pacific throughout the month. It
is noteworthy that most of
observed rainfall deficits during the month.
The oceanic thermocline, measured by the depth of the 20°C isotherm, remained deeper than average across
the central and east-central equatorial Pacific and shallower than average
in the eastern equatorial Pacific during February (Figs. T15,
Consistent with these conditions, subsurface ocean temperatures at
thermocline depth were 2-3°C
above average across the central equatorial Pacific and 2-4°C below average in the eastern equatorial Pacific (Fig.