Large Scale Tropical Heat Sources and Global Atmospheric Energy Propagation Associated with Droughts in Northeast Brazil

摘要

An analysis of the monthly departure of the relative vorticity field (zeta) over the globe and monthly departures of the sea surface temperature (SST) in the Tropical Atlantic Ocean is performed for years of droughts and floods over Northeast Brazil, in the period from 1963 to 1980. Planetary scale wavelike patterns were observed in the zeta field similar to those found in previous theoretical and observational studies. Of major interest, it is the phase coherence of the wavelike patterns of circulation anomalies over the Northern hemisphere and the precipitation regime over Northeast Brazil. Such phase coherence, in addition to the occurrence of SST anomalies in the Tropical Atlantic Ocean (with warmer waters in the north and colder in the south of the equator for drought years, and the reverse for flood years), indicates that the existence of global scale wavelike patterns in zeta field, as well as the precipitation regime over Northeast Brazil are, respectively, the remote and local response of the atmosphere to a tropical thermal forcing.