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

NOVEMBER 2007

During November 2007, equatorial sea surface temperature (SST) anomalies became increasingly negative from 160ºE to the South American coast (Fig. T18). This cooling is reflected by a drop in the monthly Niño-3.4 index to -1.5°C and a drop in the Niño-4 index to -0.9°C (Table T2). The sub-surface temperature departures remained negative across the eastern equatorial Pacific, where temperatures at thermocline depth ranged from -2°C to -4°C below average (Fig. T17).

During November 2007, low-level easterly anomalies (more than 3.0 m s^-1) and upper-level westerly anomalies (more than 5.0 m s^-1) spanned the central equatorial Pacific (Figs. T20, T21). This pattern is consistent with a shallower-than-average thermocline and the additional cooling of the surface and sub-surface ocean temperatures (Figs. T15, T16). These conditions were associated with enhanced convection (above-average rainfall amounts) over the western equatorial Pacific and a continuation of suppressed convection (below-average rainfall amounts) across the central and eastern equatorial Pacific (Figs. T25, T26, E3). Consistent with these anomalies, the Tahiti – Darwin SOI increased to +0.9 during November (Table T1, Fig. T1). Collectively, these oceanic and atmospheric conditions reflect a strengthening La Niña. 

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