Tropical Highlights

  Table of Atmospheric Indices  (Table 1)

  Table of Oceanic Indices  (Table 2)

  Time Series

  Time-Longitude Sections

  Mean & Anomaly Fields

  Appendix 1: Outside Contributions

Tropical Highlights

AUGUST 2007

During August 2007, negative equatorial sea surface temperature (SST) anomalies in the eastern equatorial Pacific expanded westward, and now extend from the coast of South America to the date line (180ºW) (Fig. T18). This pattern is reflected in negative values of the Niño 1+2 (-1.6), Niño 3 (-1.1), and Niño 3.4 (-0.5) region SST indices (Table T2). The equatorial oceanic thermocline during August, 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 1-3ºC below average at thermocline depth (Fig. T17).  

During August 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. T26, E3). Consistent with these anomalies, the equatorial SOI remained positive (+1.2) (Fig. T2), although the Tahiti – Darwin SOI was near-average (+0.1) (Table T1, Fig. T1). This overall combination of oceanic and atmospheric conditions reflects the development of La Niña conditions. 

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