Satellite altimetry application case studies from the northern Indian Ocean

Altimeters can be useful in marine as well as shoreline studies. In this chapter, we have presented both applications as two separate case studies from the northern Indian Ocean region. Physical processes in the oceans, such as eddies, gyre, currents, and upwelling, have a spatial scale of 10–100 km and a lifespan ranging from few days to weeks. Most of these processes are driven by seasonal cycles and often occur at the basin scale. Such episodes determine the spatial and vertical structure of the water mass in the region with reference to several other properties, including temperature and salinity. Upwelling and cyclonic eddies form a deeper mixed layer that facilitates nutrient entrainment across otherwise stratified waters. These nutrients constitute the lifeline for the marine food web. Nutrients are retained along the frontal structure, and these areas are proven to be good fishing zones. Such processes can be monitored using altimeters well before a radiometer can detect them in terms of temperature or ocean color. With the use of multiple active sensors, the capabilities of satellite altimetry can be optimally harnessed. Herein, we have shown the importance of Sea Surface Height anomaly (SSHa, retrieved using an altimeter) in demarcating potential fishing zones. We have also explored how SSHa can help predict tuna movements, horizontally as well as vertically, in the water column. Moreover, we have proven these predictions by positively correlating SSHa with tuna hooking rates. In another case study, we have depicted implications of sea-level rise on coastal erosion.