Presented at the 2014 Ocean Sciences MeetingDaily cycles in solar radiation, winds, and precipitation can force a diurnal cycle in near-surface salinity. This has implications both for upper ocean processes and for satellite calibration/validation. Although the daily salinity cycle has been observed in a few isolated locations, global patterns have never been shown. In the present study, salinity observations from Aquarius and Argo profiling floats are combined in order to extract the amplitude and phase of the diurnal salinity cycle throughout the tropics and subtropics. Large daily salinity ranges are seen in several regions, including the Bay of Bengal, the eastern equatorial Indian Ocean, and off the west coast of Central America. We discuss the effects of wind forcing, precipitation, and vertical mixing on diurnal salinity, as well as the implications of this work for interpreting Aquarius observations.