The annual cycle in equatorial convection and sea surface temperature

Abstract

The March equinox corresponds to the warm season when the equatorial cold tongues in the eastern Pacific and Atlantic are absent. With the onset of summer monsoon convection over Colombia, Central America, and West Africa in May-June, northward surface winds strengthen over the eastern Pacific and Atlantic, the equatorial cold tongues reappear, and the marine convection shifts from the equatorial belt to the intertropical convergence zones (ITCZs) along 8°N. As the northern summer progresses, the ITCZs remain strong and shift northward to near 10°N, while sea surface temperature (SST) continues to drop over the cold tongues and the southern tropics, perhaps in response to the expanding stratocumulus cloud decks in the latter region. The cold tongue-ITCZ complex persists through the September equinox, which is characterized by suppressed convection, not only over the cold tongues, but also over much of equatorial South America. -from Authors