Thermal small steps staircase and layer migration in the Atlantis II Deep, Red Sea
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Atlantis II Deep, a submarine basin of the Red Sea, is noteworthy because of its hydrothermally active brine pools. High-resolution temperature records from Poseidon Cruise during February 2011 revealed small steps thermal staircase in the lower transition zone from ≈2002 to 2008/2009 m depth at stations. Four vertically well-mixed convective layers, lower convective layer (LCL) and upper convective layers (UCL1–3), separated by high-temperature gradients at the interfaces were observed. The temperature of the layers UCL1–3 has dropped between 2008 and 2011. The top of UCL3 extends to about 2008/2009 m at stations and its average thickness has increased from 3.3 ± 0.5 m in 1992 to 7 m in 2011, whereas the thickness of layers UCL1–2 has decreased from 25.2 ± 0.3 m to 19.8 m and from 16.4 ± 0.5 m to 14.7 m, respectively, during this time. The upward buoyancy flux is 0.032 to 0.038 × 10−7 m2 s−3 which gives migration speed of UCL3 layer from 0.1 to 0.12 m year−1. With this speed, the thermal staircase ≈6 m thick will merge with UCL3 in 50 to 60 years increasing the thickness from 7 m to nearly 13 m.
KeywordsAtlantis II Deep Red Sea Double-diffusive layering Thermal staircase merger
The Jeddah Transect Project, a collaboration between King Abdulaziz University and Helmholtz Center for Ocean Research GEOMAR, was funded by King Abdulziz University (KAU) Jeddah, Saudi Arabia, under grant no. (T-065/430-DSR). The authors acknowledge with thanks KAU technical and financial support. The patience and cooperation of the captain and crew of R/V Poseidon in collecting the data are highly appreciated.
- Anschutz P (2015). Hydrothermal activity and paleoenvironment of the Atlantis II Deep: In Rasul N, Stewart, ICF (eds) The Red Sea: deformation, morphology, oceanography and environment of a young ocean basin. Chapter 14 pp. 235–249 Springer, Berlin.Google Scholar
- Blanc G, Anschutz P (1995) New stratification in the hydrothermal brine system of the Atlantis II Deep. Red Sea Geology 23:543–546Google Scholar
- Marmorino GO, Caldwell DR (1976) Heat and salt transport through a diffusive thermohaline interface. Deep Sea Res 23:59–67Google Scholar
- Radko T (2013) Double diffusive convection. Cambridge University PressGoogle Scholar
- Schmidt M, Busbridge M, Wuest A (2010) Double-diffusive convection in Lake Kivu, Limnol. Oceanogr 55(1):225–238Google Scholar
- Timmermans ML, Toole J, Krishfield R, Winsor P (2008) Ice-tethered profiler observations of the double-diffusive staircase in the Canada Basin thermocline. J Geophys Res 113(C000A02):1–10Google Scholar
- Turner JS (1973) Buoyancy effects in fluids: Cambridge University Press, Cambridge, p. 367.Google Scholar
- Wall SE (2007) Structure and evolution of thermohaline staircase in tropical North Atlantic. M.Sc. thesis, Naval Postgraduate School, Monterey, California, USAGoogle Scholar
- Wilson AL (2007) Structure and dynamics of the thermohaline staircase in the Beaufort Gyre. M.Sc. thesis, Naval Postgraduate School, Monterey, California, USAGoogle Scholar
- Wüest A, Sommer T, Schmid M, Carpenter JR (2012) Diffusive-type of double diffusion in lakes—a review. Chapter 14 in W. Rodi and M. Uhlmann (eds), Environmental fluid mechanics: memorial volume in honour of Prof. Gerhard H. Jirka, IAHR Monographs, 271–284.Google Scholar