The calm and variable inner life of the Atlantic Intertropical
Convergence Zone: the relationship between the doldrums and surface
convergence
Abstract
The doldrums are regions of low wind speeds and variable wind directions
in the deep tropics that have been known for centuries. Although the
doldrums are often associated with the Intertropical Convergence Zone
(ITCZ), the exact relationship remains unclear. This study re-examines
the relationship between low-level convergence and the Atlantic
doldrums. By analyzing the frequency distribution of low wind speed
events in reanalysis and buoy data, we show that the doldrums are
largely confined between the edges of the ITCZ marked by enhanced
surface convergence. While the region between the edges is a region of
high time-mean precipitation, low wind speed events occur in the absence
of precipitation. We therefore hypothesize that low wind speed events
occur in regions of low level divergence rather than convergence.