Eddy-Induced Temperature and Salinity Variability in the Arabian Sea

The eddy field in the Arabian Sea experiences seasonal wind-driven intensification during the summer monsoon season from June through September. These strong eddies strengthen local currents like the Somali Current and strongly impact regional upper-level vertical and lateral advection. To investigate the multivariate response to eddying, we apply a closed-contour eddy-tracking algorithm to sea level anomaly maps and then examine sea surface temperature and salinity of the identified eddies to infer whether they are surface or subsurface intensified in the Arabian Sea during the summer monsoon. A complete understanding of the temperature and salinity signatures reveals how Arabian Sea eddies alter upper-ocean stratification. Though both intensification types are identified, we find a dominance of likely surface-intensified eddies characterized by relatively warm and fresh cores for anticyclonic eddies and relatively cool and saline cores for cyclonic eddies, particularly in the northwestern Arabian Sea and Somali Current region. Plain Language Summary Mesoscale eddies in the ocean, analogous to their atmospheric cyclone and anticyclone counterparts, play a major role on the transport and redistribution of oceanic properties like heat or salt. They are highly variable and transient, so to fully understand their behavior, eddy tracking algorithms are typically used to identify these features and follow their trajectories. In this study, we apply an algorithm to sea level anomalies in order to track eddy formation, distribution, and duration during the summer monsoon season in the Arabian Sea. In sea surface height, cyclonic (anticyclonic) eddies appear as low (high) sea level anomalies. Though the overall displacement of the eddy can be estimated with sea level anomalies alone, a more in-depth investigation of the temperature and salinity at the surface and subsurface can provide insight to the vertical structure of the eddy. More specifically, a multiparameter approach allows for investigation of whether an eddy intensifies at or below the surface. This research analyzes the characteristics of eddies in the Arabian Sea during the southwest monsoon seasons from 2015 to 2018.