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

SEPTEMBER 2008

ENSO-neutral conditions continued during September 2008, as sea surface temperatures (SSTs) in the east-central equatorial Pacific Ocean remained near-average (Fig. T18).  The latest monthly SST index was -0.2°C in the Niño-3.4 region, and -0.4°C in the Niño-4 region (Table T2).

The oceanic thermocline, measured by the depth of the 20°C isotherm along the equator, featured shallower-than-average depths in the east-central equatorial Pacific during September (Figs. T15, T16). Consistent with this, equatorial oceanic temperatures at thermocline depth were 1-3 ^oC below average in the east-central equatorial Pacific (Fig. T17).

However, the atmospheric circulation continued to reflect some lingering aspects of La Niña, with enhanced low-level easterly winds and upper-level westerly winds over the western and central tropical Pacific (Figs. T20, T21, Table T1). Also, convection remained suppressed throughout the central equatorial Pacific and enhanced over Indonesia (Figs. T25, T26 and E3).

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