Tropical Highlights - July 2007

 

Tropical sea surface temperatures (SSTs) during July 2007 were near-average across the western and central equatorial Pacific and colder-than-average over the eastern tropical Pacific (Fig. T18). This pattern is reflected in negative values of the Niño 1+2   (-1.6), Niño 3 (-0.8), and Niño 3.4 (-0.3) region SST indices (Table T2). Meanwhile, the Tahiti – Darwin SOI was slightly negative (latest value: -0.5) in response to higher than average pressure over Darwin (Table T1, Figs. T1). These conditions indicate a continuation of ENSO-neutral conditions.

 

The equatorial oceanic thermocline during July, measured by the depth of the 20ºC isotherm, featured a continuation of below-average depths over the eastern equatorial Pacific and near-average depths across the western and central equatorial Pacific (Figs. T15, T16). As a result, temperatures in the eastern equatorial Pacific remained generally 1-2ºC below average at thermocline depth (Fig. T17).

 

During July 2007, low-level easterly anomalies (more than 3.0 m s^-1) were observed over the central equatorial Pacific (Fig. T20). This anomaly pattern has persisted since February (Fig. T13), and is consistent with the shallower-than-average thermocline and cooler SSTs farther east. This wind pattern was also associated with enhanced convection (above-average rainfall amounts) across Indonesia , and a continuation of suppressed convection (below-average rainfall amounts) across the central and eastern equatorial Pacific (Figs. T25, E3).

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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