Seasonal and Interannual Variability of the Thermohaline Structure of the Bengel Upwelling Based on the Argo Buoys Data

Purpose. The work is purposed at studying the water vertical structure in the Bengel upwelling region based on the Argo buoys data, its seasonal and interannual variability, as well as the possibility of using altimetry measurements to assess intensity of the eastern upwellings. Methods and Results. Based on the Argo buoys measurements for 2004-2019, the spatial, seasonal and interannual variability of the Bengel upwelling thermohaline structure was investigated. With increase of depth, the zone of the deep water rise was observed to shear to the south and to the west. The maximum upwelling on the surface was recorded at latitude 25 degrees S. However, the water rise in this zone was observed only up to the 300 m depth. At the same time, at latitude 30 degrees S, the water rise was less intense on the surface, but was noted within the depth range 0-1500 m. Within the 100-600 m layer, seasonal variations of the temperature and salinity anomalies in the central part of the Bengel upwelling were almost the same. Conclusions. Upwelling is most intense in July and weakens in April. At this time, the temperature and salinity anomalies within the 100-600 m layer reach 0.5 degrees C and 0.05 psu, respectively. The secondary maximum of upwelling is observed in January in the 0-400 m layer, and its secondary minimum - in December. On the interannual scales (2004-2019), two periods of the upwelling significant weakening were recorded: in 2004-2005 and in 2018-2019.