A systematic method of estimation of alongshore windstress and Ekman transport associated with coastal upwelling

A standard method for estimating alongshore windstress (AWS) and related cross-shore Ekman transport (ET) is proposed. In the absence of standard methodologies for estimating coastal angles required for AWS estimation, an estimation is typically derived on a case-to-case basis, often approximating entire coastlines with a single line segment. A novel standard parametric method for estimating this coastal angle is developed in this manuscript consisting: • Computation of Coastal Angle from Global Self-consistent Hierarchical High-resolution Shoreline (GSHHS) coastline data through line simplification; • Estimation of Windstress components at coastal points from Copernicus Marine Environment Monitoring Service (CMEMS) wind data; • Estimation of AWS and associated Ekman Transport. The method developed was demonstrated for the eastern and western coasts of India. While, a single line approximation was adequate for representing the west coast of India (a nearly linear coastline), an ET variation greater than 20% was introduced by oversimplification of the coastline for the east coast, which has significant curvature. This demonstrated the relevance of our systematic approach for coastline simplification, emphasizing the significance of accurate determination of coastal angles for computing ET simultaneously.