Diurnal Cycle of Winds and Convection in the ITCZ

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.