Tropical Highlights - May 2005

     

The pattern of global tropical sea surface temperature (SST) during May 2005 featured negative anomalies in the eastern equatorial Atlantic and near-average SSTs elsewhere. The SST anomaly in the Niño 3.4 region remained 0.4 during May and the Niño 1+2 anomaly became slightly positive for the first time since December 2004 (Fig. T18, Table T2). The overall patterns of convection, SST, low-level winds and upper-level winds were near average over the tropical Pacific during May, which is consistent with ENSO-neutral conditions.

Intraseasonal (Madden-Julian Oscillation - MJO) activity during May contributed to week-to-week variability in many tropical atmospheric features (Figs. T10, T11, T12, T13). The Tahiti - Darwin SOI (latest value -1.2, Table T1, Fig. T1) was negative, primarily in response to higher-than-average pressure over Darwin.

The oceanic thermocline, measured by the depth of the 20°C isotherm, featured near-average depth across the equatorial Pacific during May (Figs. T15, T16). Consistent with these conditions, oceanic temperatures at thermocline depth were near average throughout most of the equatorial Pacific (Fig. T17).