Seasonal Variability of Sea Surface Salinity and Precipitation in the Tropical Ocean from Mooring Data

Abstract:

Using data from the Global Tropical Moored Buoy Array, we examine the seasonal variability of sea surface salinity (SSS) and rainfall. As the northern tropics under the intertropical convergence zone are an important part of the global water cycle on the seasonal time scale, quantification of the surface water balance is important in this region. Seasonal harmonics of both quantities were computed to determine amplitude and phase. Amplitudes were compared using an estimate of mixed-layer depth along with a simplified salinity balance equation. Phases generally matched well, with a 2-3 month lag between maximum rainfall and minimum SSS. Amplitudes were generally larger for northern hemisphere moorings than southern in the Pacific basin, and vice versa for the Atlantic and Indian basins. Amplitudes of SSS harmonics ranged from zero up to almost 1 pss.