Diurnal Cycle of Winds and Convection in the ITCZ

Abstract:

The recently launched RapidSCAT scatterometer measures surface winds over the global oceans at different times of day, in contrast to previous sun-synchronous satellites (e.g. QuikSCAT). RapidSCAT therefore resolves diurnal wind variability better than previous satellites, opening a new window on the diurnal cycle of convection. Here we examine diurnal wind variability in the ITCZ region and its relation to the diurnal cycle of convection; the satellite wind signals are noisy but we find both diurnal and semidiurnal signals in the ITCZ surface winds that correspond to robust cloud signals. We find a poor agreement between the diurnal wind-convection relationship in observations and in a global, explicit-convection atmospheric model.