Ocean Science

Ekman and Geostrophic Currents

The ocean surface currents are estimated from satellite observations of surface wind from Oceansat-2 Scatterometer and Sea Surface height from SARAL AltiKa. The Ekman Surface current estimated from wind stress components and geostrophic current estimated form SARAL AltiKa are combined to generated ocean surface currents. The data sets available since March 2013. The products are validated with drifting buoy observations indicating a good relationship between the observations.

The wind-driven currents (or Ekman currents) are the resultant of frictional force exerted by wind on the ocean surface. The wind blows across the ocean and moves its waters as a result of its frictional drag on the surface. Once the wind sets surface waters in motion as a current, the Coriolis force, Ekman transport, and the configuration of the ocean basin (topography) modify the speed and direction of the current.Ekman Currents are estimated using data from scatterometer sensors, viz., OSCAT (April, 2013 - Feb,2017) and SCATSAT (Mar,2017-till date) wind composites on a daily basis.

Under the effect of the pressure-gradient force, the water tends to move from the region of high pressure to that of low pressure. And this flow of water balanced by Coriolis force leads to Geostrophic currents. Geostrophic currents are proportional to the height gradient divided by the Earth's rotation parameter f, which is the lowest-order balance for quasi-steady circulation at higher latitudes. Height gradient has been computed by using Saral-AltiKa sea surface height anomaly (SSHA) and mean dynamic topography data. Geostrophic Currents are computed on daily basis by assimilating and gridding the past 15 days along track SSHA data.

Ekman Currents information is hosted on Bhuvan-Ekman Curretns, Select NICES Project - Terrestrial Sciences –Ekman Currents , List and view the data of the selected time period. Technical Document(hyper link : Ekman Currents)

Geostrophic currents information is hosted on Bhuvan-Geostrophic currents . Select NICES Project - Terrestrial Sciences –Geostrophic Currents, List and view the data of the selected time period. Technical Document(hyper link : Geostrophic Currents)