Independent Eddy Identification With Profiling Argo as Calibrated by Altimetry
Ge Chen, Xiaoyan Chen, Baoxiang Huang
Abstract
Abstract Thousands of mesoscale eddies are now routinely tracked on daily basis in the global ocean, thanks to the state of the arts technology of tandem satellite altimetry. Despite the obvious success, it has been recently recognized that a substantial portion of oceanic eddies may still be missed out due to inadequate spatiotemporal sampling by available altimeters. As an effort to tackle this problem, we propose a methodology to effectively expand the capacity of eddy tracking by using altimetrically “calibrated” Argo measurements. The idea is to develop an independent identification scheme which relates eddy surface signature to its interior property based on the fact that sea surface topography detected by altimetry is highly correlated to the vertical structure of potential density anomaly derived from Argo profiles. Among the nearly 4,000 active Argo floats about one third are found to fall into altimeter‐captured eddies, and roughly one fourth additional floats are identified by the verified Argo‐alone criteria as onboard eddies outside altimetrically derived ones (i.e., which would otherwise be overlooked by altimeters). In particular, Argo‐based eddy identification is found to compensate that of altimetry by partially rectifying its ineffectiveness in low latitude areas, as well as its misclassification of eddy polarity oceanwide which accounts for 4.3% of the altimeter‐identified eddy population.