Three-dimensional thermohaline anomaly structures of mesoscale eddies in the South China Sea

Abstract

Used the Sea Level Anomaly data during 1994 to 2015, based on the winding-angle eddy detection algorithm, total of 5 899 anticyclonic eddies (AE) and 3 792 cyclonic eddies (CE) in the SCS are identified. With the profiles from the WOD13 and the SCSIO, the 3-D thermohaline anomaly structures are constructed in the SCS and its different area with the objective interpolation approach based on the variational analysis. The results show that the proposed revised interpolation approach can simulate the boundary of eddies effectively, and ensure the correct eddies shape. Generally speaking, AE's intensity are obviously stronger than CE's. AE maintain its main structure till approximately 440 m depth while CE only remain stable above 320 m. Both of the maximum potential temperature anomalies appear in about 80m depth, 2.02℃ for AE and -1.60℃ for CE. The affecting depth of salinity anomaly of eddies reach to 150 m depth around and the maximum anomalies induced by AE and CE are -0.24 and 0.28, respectively, which occur near the depth of 50 m. Meanwhile, the structure of salinity anomaly of AE seems to be positive on the top and negative on the bottom, just opposite to CE,which attributed to the sea water sinking (rising) induced by AE(CE). The temperature anomalies in each area of the SCS are not quite consistent with the salinity anomalies, which may attributed to the background thermohaline fields and different formation mechanism of eddies.