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Climate Diagnostics Bulletin
Climate Diagnostics Bulletin - Home Climate Diagnostics Bulletin - Forecast Climate Diagnostics Bulletin - Extratropics


  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


The pattern of tropical sea surface temperature (SST) anomalies

Tropical Highlights - September 2021



During September 2021, sea surface temperatures (SSTs) were near-to-below average across much of the central and eastern equatorial Pacific (Fig. T18). The latest monthly Niņo indices (based on OISST) were +0.1°C for the Niņo 1+2 region, -0.3°C for the Niņo 3.4 region and -0.4°C for the Niņo 4 region (Fig. T5, Table T2). The depth of the oceanic thermocline (measured by the depth of the 20°C isotherm) was below-average across the eastern equatorial Pacific (Figs. T15, T16). The corresponding sub-surface temperatures were 1-6°C below-average (Fig. T17).


Also during September, the lower-level easterly winds and the upper-level westerly winds were above-average over much of the equatorial Pacific (Table T1, Fig. T20, Fig. T21). Meanwhile, tropical convection was suppressed near and west of the Date Line and enhanced over Indonesia (Figs. T25, E3). Collectively, these oceanic and atmospheric anomalies were consistent with La Niņa conditions.


For the latest status of the ENSO cycle see the ENSO Diagnostic Discussion at:

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