Tropical Highlights - April 2006

 

The pattern of global tropical sea surface temperature (SST) during April 2006 featured negative anomalies in the eastern equatorial Pacific and near-average SSTs elsewhere (Fig. T18, Table T2).  The SST anomaly in the Niño 1+2 region is -1.2 (Table T2). Meanwhile, the Tahiti - Darwin SOI (latest value 0.9, Table T1, Fig. T1) was still positive, in response to lower-than-average pressure over Darwin (Fig. T19). The latter is consistent with enhanced convection over the western tropical Pacific, including northern Australia during April (Fig. T25).

The oceanic thermocline, measured by the depth of the 20°C isotherm along the equator, featured slightly deeper-than-average depth across the central and east-central Pacific and shallower-than-average depth in the eastern Pacific during April (Figs. T15, T16). Consistent with these conditions, equatorial oceanic temperatures at thermocline depth were 1-2^oC above average across the central and east-central equatorial Pacific and 2-4^oC below average in the eastern equatorial Pacific (Fig. T17).

During April, low-level easterly anomalies (more than 3.0 m s^-1) were observed over the central equatorial Pacific and westerly anomalies were observed over Indonesia (Fig. T20). Enhanced convection (above-average rainfall amounts) was observed over Indonesia , northern Australia and the Philippines (Figs. T25, T26 and E3).