title: Rapid vertical mixing rates in deep waters of the Andaman Basin.
abstract: The Andaman Basin is an enclosed region in the northeastern Indian Ocean with its deep water below approximately 1800 m almost isolated with respect to horizontal ventilation by the Andaman-Nicobar Islands separating it from the Bay of Bengal. The physical and chemical properties including radiocarbon ((14)C) measured at two stations of the Andaman Basin show negligible variation with depth in the waters below 1300 m, indicating a well-mixed water mass. This study attempts to derive the mixing rates for deep waters of the Andaman Basin. Model calculations based on (14)C profile measurements indicate rapid vertical mixing (vertical advection velocity, w>200 m year(-1)) in waters deeper than 1800 m of the basin. For a basin with deep water thickness of 1000 m below 1800 m, deduced mixing rate of >200 m year(-1) translates to mixing time of <5 years. As shown for other regions, the possible mechanism responsible for such high vertical mixing rates could be the internal waves generated from tidal currents flowing through rough topography. In addition, Andaman Basin is underlain with a young crust and is known for its high heat flow, which also could contribute to the high vertical mixing.
authors.affiliation: Planetary and Geosciences Division, Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India.
authors.forename: Koushik
authors.initials: K
authors.lastname: Dutta
authors.forename: Ravi
authors.initials: R
authors.lastname: Bhushan
authors.forename: B L K
authors.initials: BL
authors.lastname: Somayajulu
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis; D002250:Carbon Radioisotopes; D019156:Indian Ocean; D009566:Nitrates / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D012623:Seawater / Q000737:chemistry*; D017640:Silicates / Q000032:analysis; D012965:Sodium Chloride / Q000032:analysis; D013696:Temperature; D014872:Water Movements
chemical_list: D002250:Carbon Radioisotopes; D009566:Nitrates; D017640:Silicates; D002245:Carbon Dioxide; D012965:Sodium Chloride; D010100:Oxygen