Tropical Highlights - January 2006

 

The pattern of global tropical sea surface temperature (SST) during January featured  negative anomalies in the east-central  equatorial Pacific, with January values of -0.9 in the Niño 3.4 region and -0.4 in the Niño 4 region (Fig. T18, Table T2). Meanwhile, the SST anomalies in the eastern tropical Pacific increased slightly, with the latest value of -0.3 in the Niño 1+2 region (Fig. T18, Table T2). The Tahiti - Darwin SOI (latest value 1.8, Table T1, Fig. T1) was positive, in response to higher-than-average pressure over Tahiti and lower-than-average pressure over Darwin . The latter is consistent with enhanced convection over the western tropical Pacific, including northern Australia (Fig. T25).

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

During January, near-average low-level winds were observed over the eastern equatorial Pacific while low-level easterly anomalies (more than 3.0 m s^-1) were observed over the central equatorial Pacific (Fig. T20). In the global tropics, enhanced convection (above-average rainfall amounts) was observed over the western tropical Pacific and across the tropical North Atlantic (Figs. T25, T26 and E3).