Composite analysis and complex empirical orthogonal function analysis shows that 30-90 day precipitation anomalies are generally zonally-elongated, grow and decay in place, and have maximum amplitude near the Gulf of Guinea and in the Atlantic ITCZ. Composite 30-90 day enhanced precipitation events are accompanied by a significant suppression of eastern north Atlantic trades winds. Suppressed 30-90 day precipitation events are associated with an enhancement of the Atlantic trade winds. Enhanced (suppressed) EKE occurs just to the north of the east Atlantic ITCZ during positive (negative) 30-90 day precipitation events, with the maximum EKE magnitude lagging precipitation events by about 5 days.
East Atlantic tropical cyclone activity is significantly modulated on intraseasonal timescales. The number of tropical cyclones that occur in the Atlantic main development region to the east of 60°W is suppressed about 5-10 days before maxima in a regional intraseasonal precipitation time series, and enhanced about 5-10 days after time series maxima. An analysis of east Atlantic tropical cyclone activity based on an equatorial MJO index produces similar results. Consistent with the results of Mo, variations in vertical shear may help explain this modulation of tropical cyclone activity.