Tropical Squall Lines over the Eastern Atlantic during GATE

Abstract

During the entire period of GATE, all oceanic squall lines over the A/B array developed in the vicinity of the near-equatorial convergence zone (NECZ) when a strong midtropospheric easterly jet along the leading and southern borders of a Saharan air outbreak was observed at the Acad. Korolov. The peak magnitude of the jet, averaged between 700 and 600 mb, exceeded 16 m s?1 for all squall line occurrences. Phase III easterly wave activity was the most pronounced of the three phases. Every wave of Phase III with a Saharan air outbreak preceding the trough-produced squall lines. It is suggested that the presence of the Saharan air ahead of the trough is favorable for the development of squall lines in the vicinity of NECZ over the eastern Atlantic.