Geostrophic currents in the Northern Lembata Waters: from OTEC Cruise observation in September–October 2017

Abstract The Northern Lembata Waters (NLW) is located in the Flores Sea that its dynamics is strongly affected by Monsoon Current and the Indonesian Throughflow (ITF). This study aims to describe the physical characteristics of the waters and geostrophic current, using observation CTD data from OTEC Cruise 2017. The type of water mass is identified using T-S diagram, and geostrophic currents is determined using a reference level at 600 dbar. From its characteristics such as temperature, salinity, and density it can be deduced that the waters vertically stratified. It is revealed a strong geostrophic flow due to water density differences. In the upper layer (0–300 dbar) geostrophic velocity ranged from 12.59 to 343.93 cm s−1 flowing eastward and in the deeper layer (300–600 dbar) geostrophic velocity (in section B) ranged from 7.66 to 49.19 cm s−1 flowing westward. The eastward flow is considered to be part of the ITF, and the westward flow at deeper layer may be associated with density-driven flow between Banda and Flores Seas.