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Observations of Barrier Layer Seasonal Variation in the Banda Sea
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  • Mochamad Furqon Azis Ismail,
  • Johannes Karstensen,
  • Albertus Sulaiman,
  • Bayu Priyono,
  • Asep Sandra Budiman,
  • Abdul Basit,
  • Adi Purwandana,
  • Taslim Arifin
Mochamad Furqon Azis Ismail
National Research and Innovation Agency of Indonesia

Corresponding Author:[email protected]

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Johannes Karstensen
Helmholtz Centre for Ocean Research Kiel (GEOMAR)
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Albertus Sulaiman
National Research and Innovation Agency of Indonesia
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Bayu Priyono
National Research and Innovation Agency of Indonesia
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Asep Sandra Budiman
National Research and Innovation Agency
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Abdul Basit
National Research and Innovation Agency
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Adi Purwandana
Research Center for Oceanography - National Research and Innovation Agency (RCO-BRIN)
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Taslim Arifin
Marine Research Center, Ministry of Marine Affairs and Fisheries of Republic of Indonesia
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Abstract

The Banda Sea is of crucial importance for the circulation of the world’s oceans, as it is part of the connection between the Pacific to the Indian Ocean. One peculiarity of the upper ocean hydrography in the Banda Sea is the occurrence of barrier layers. The regionality and temporal variability of barrier layer thickness (BLT) in the Banda Sea are examined in this study utilizing in-situ observations and ocean reanalysis output. It is found that a barrier layer occurs in over 90 % of the observational data profiles, and in over 72 % of those profiles, the BLT is shallower than 10 m. Furthermore, we find a seasonal cycle in BLT with a maximum thickness of about 60 m occurring during austral autumn and winter and coinciding with the presence of low saline waters fed by the regional river discharge and rainfall from the Java Sea and Makassar Strait. In addition, we identify the existence of a quasi-permanent anticyclonic circulation cell in the Banda Sea that may support the trapping of surface freshwater by retention. The anticyclonic circulation is most likely wind-driven because it coincides with the regional Ekman pumping pattern. Modulation of the anticyclone is via seasonal variability in the wind stress curl which in turn may explain the efficiency of freshwater retention and thus the BLT. The annual mean BLT distribution in the Banda Sea shows a preferential region of thickened barrier layers around 6o-8oS and 124o-126oE and resampling the pattern of the monthly mean climatology.