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Tropical Highlights
MARCH 2008
Forecast Forum
Atmospheric
and oceanic conditions during March 2008 reflected a moderate La Niña.
Equatorial sea surface temperatures (SSTs) in the
Pacific
Ocean
remained below average from west of the Date Line eastward to 120°W. However,
these departures weakened during the month (Fig.
T18),
and the latest Niño-3.4 and Niño-4 index values were only
slightly cooler than -1°C (Table
T2). Meanwhile, the SST anomalies near the west
coast of
South
America
have been positive since February 2008 (Table
T2, Figs. T9,
T18).
The
oceanic thermocline remained shallower than normal east of 140°W and continued
to deepen in the region west of the Date Line (Fig. T16). Consistent with this
structure, sub-surface temperature at thermocline depth remained below average
(-1°C to -4°C) across the eastern equatorial Pacific, and above average west
of 170°W (Fig. T17).
Strong
low-level easterly anomalies persisted across the western and central equatorial
Pacific during the month (Fig. T20,
Table T1),
which is consistent with the shallower-than-average thermocline in the central
and eastern equatorial Pacific (Figs. T15,
T16). These conditions were associated with
enhanced convection (above-average rainfall amounts) across the
Indian Ocean
,
Indonesia
and the far western
tropical Pacific, and a continuation of suppressed convection (below-average
rainfall amounts) across the central equatorial Pacific (Figs.
T25, E3).
Consistent with these anomalies, the
Tahiti
– Darwin SOI remained
positive (+1.1) (Table T1,
Fig. T1), and the equatorial SOI was +2.4 (Fig.
T2).
For
the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at:
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory/index.html
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