On the Change in the Ocean Surface Temperature in the Benguela Upwelling Region. Part I: Season Cycle

Abstract

Based on the daily satellite imagery data on the ocean surface temperature for 1982–2017, near-surface wind for 1988–2017 and sea-level anomalies for 1993–2017, the seasonal variability of the hydrothermodynamic characteristics of the upper water layer in the vicinity of the Benguela upwelling is investigated. It is shown that the thermal upwelling index averaged over the entire area with lower temperature values does not provide a correct idea of the seasonal course of the water lifting rate in the upwelling zone due to the significant horizontal advection of waters of upwelling origin. The seasonal variation in the vertical velocity of wind origin in the Benguela upwelling zone is characterized by the presence of two extremums from October to March, which is manifested in the dominance of the semiannual harmonic over the annual one. At the same time, the thermal upwelling index in the zone of distribution of upwelling waters is subject to seasonal variability with an annual period.