An eddy-borne Argo float measurement experiment in the South China Sea

Abstract

Argo floats can be used to collect unique and spatiotemporally continuous eddy profiles as they are carried forward within eddies. Using satellite altimeter data, we designed and conducted an eddy-borne Argo float measurement experiment in a South China Sea (SCS) eddy generated in the southwest region of Taiwan. The Argo float was deployed at a location that was estimated to be in the eddy corridor on December 31, 2016. As a result, the Argo float continuously observed the target eddy for more than 2 months, and successfully obtained 62 valuable daily temperature (T) and salinity (S) profiles inside this eddy. From this Argo float’s movement, the smooth transition of the float speed and heading revealed that the eddy splitting identified by satellite altimeter data should be an artifact from January 14 to 18, 2017. In addition, it is found that the depth of thermocline is negative correlated with the normalized radial distance of the float to the eddy center, and the bowl-like shape of the thermocline depth can be revealed. The T-S diagram of Argo float profiles indicated that eddy water should be derived from the Kuroshio Current. The design and implementation of this experiment are a successful example of SCS eddy observation, which will undoubtedly guide oceanographers to obtain more effective eddy data. The development of an “Eddy-Argo” program designed for eddy observation is worthy of additional research in the future.