The oceanic thermocline remained deeper than normal across most of the equatorial Pacific during April (Fig. T15) with the largest depth anomalies located in the central Pacific between 170°E and 155°W and in the extreme eastern Pacific (Figs. T15, T16). Ocean temperature anomalies at thermocline depth were also largest (+2 to +4°C) in the central and extreme eastern equatorial Pacific, and near normal to slightly below normal between 140°W and 105°W (Fig. T17). The thermocline has shoaled during the past few months between 170°W-110°W (Fig. T15), resulting in the disappearance of the large positive temperature anomalies (+4°C) observed in this region during February 2002 (Fig. T17).

Enhanced tropical convection during April was observed over the eastern equatorial Pacific, coastal Peru, and Ecuador, and across the equatorial Atlantic and equatorial western Africa (Fig. T25). Tropical convection was near-normal across the western Pacific, and slightly below normal over both the central Pacific (Fig. T8, top), and northern Australia (Fig. T25). The above-average convection over the equatorial Atlantic and western equatorial Africa was associated partly with the MJO (Fig. T11). The enhanced convection that was observed between 160°E and the date line (180°) during December 2001 – March 2002 was absent during April (Figs. T8, T11).

Both the low-level (850-hPa) and upper level (200-hPa) winds were near normal across the equatorial Pacific during April (Figs. T20, T21). For most of the past year the low-level equatorial winds have generally been near normal over the Pacific basin (Table T1, Fig. T4), while the upper-level winds have fluctuated between near-normal and stronger-than-normal westerlies. As such, no El Niño signal is yet evident in these wind patterns.