Science Meetings

Relating River Discharges to Salinity Changes
Xie, X., Liu, W., Clark, E., and Xing, Y. (12-Nov-14)

New river discharge data recently produced from terrestrial hydrology models and river gauge measurements, as part of the NASA Energy and Water studies, are brought together with spacebased sea surface salinity measurements by Aquarius and SMOS to demonstrate the role of river discharge in salinity changes near three river mouths: the Mississippi, the Ganges, and the Amazon. The characteristics of the seasonal cycle and the year-to-year changes of the river runoff are described. Various versions of the satellite salinity data are compared. The relative roles of river discharge, surface water flux, and horizontal advection in changing surface salinity in regions near the river mouths are examined. Satellite measurements of SSS clearly track movements of the fresh water from river discharges. Besides the river discharge, E-P plays an important role in the seasonal salinity variation near the Ganges and Irrawaddy River mouths. For the Mississippi and Amazon river mouths, the central and eastern Atlantic ITCZ, E-P contributes very little to the salinity seasonal change. In the central and eastern Atlantic ITCZ, contribution of advection to the salinity tendency is clearly identified. Both salinity and salinity tendency are dominated by semi-annual cycle in the Atlantic ITCZ between 5°N to 9°N, whereas annual cycle dominates at other latitudes.