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

MARCH 2011

La Niña continued to weaken during March 2011 as the magnitude of the negative sea surface temperature anomalies continued to decrease across much of the equatorial Pacific Ocean (Fig. T18, Table T2). The latest monthly Niño indices were -1.0°C for the Niño 3.4 region and -0.4°C for the Niño 1+2 region (Table T2, Fig. T5). Consistent with these conditions, the oceanic thermocline (measured by the depth of the 20°C isotherm) became slightly deeper than average over the eastern equatorial Pacific during March (Figs. T15 and T16), with sub-surface temperatures reaching 1°C above average in this region (Fig. T17).

However, the atmospheric circulation patterns during March continued to show La Niña impacts.  The equatorial low-level easterly trade winds remained stronger than average over the western and central Pacific (Table T1, Fig. T20), while convection remained enhanced over Indonesia and suppressed across the western and central equatorial Pacific (Figs. T25 and E3). Collectively, these oceanic and atmospheric anomalies reflect a weakening 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