 |
Tropical Highlights
FEBRUARY 2008
Forecast Forum
Atmospheric
and oceanic indices during February 2008 indicated a further strengthening of La
Niña. This strengthening is highlighted by a decrease in the Niño 4 sea
surface temperature (SST) index to -1.6 and a drop in the Niño 3.4 index to
-1.9, the lowest value since January 2000. Overall, equatorial sea surface
temperatures (SST) were more than 2.0°C below average across parts of the
central and east-central equatorial Pacific (Fig. T18). Meanwhile, the SST anomalies
in the Niño 1+2 region became positive for the first time since February 2007 (Table T2, Figs.
T5, T18).
Accompanying
these surface conditions, the oceanic thermocline during February remained
shallower than normal across the equatorial Pacific east of 150°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
(-2°C to -5°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, T26, E3).
Consistent with these anomalies, the
Tahiti
– Darwin SOI remained
strongly positive for the third consecutive month (+2.7) (Table
T1, Fig. T1), while the
equatorial SOI remained above +3.0 (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
|
 |
www.nws.noaa.gov
