Formation and spreading of Red Sea Outflow Water in the Red Sea

Ping Zhai, Amy S. Bower, William M. Smethie, Larry J. Pratt

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


Hydrographic data, chlorofluorocarbon-12 (CFC-12) and sulfur hexafluoride (SF6) measurements collected in March 2010 and September-October 2011 in the Red Sea, as well as an idealized numerical experiment are used to study the formation and spreading of Red Sea Outflow Water (RSOW) in the Red Sea. Analysis of inert tracers, potential vorticity distributions, and model results confirm that RSOW is formed through mixed-layer deepening caused by sea surface buoyancy loss in winter in the northern Red Sea and reveal more details on RSOW spreading rates, pathways, and vertical structure. The southward spreading of RSOW after its formation is identified as a layer with minimum potential vorticity and maximum CFC-12 and SF6. Ventilation ages of seawater within the RSOW layer, calculated from the partial pressure of SF6 (pSF6), range from 2 years in the northern Red Sea to 15 years at 17N. The distribution of the tracer ages is in agreement with the model circulation field which shows a rapid transport of RSOW from its formation region to the southern Red Sea where there are longer circulation pathways and hence longer residence time due to basin wide eddies. The mean residence time of RSOW within the Red Sea estimated from the pSF6 age is 4.7 years. This time scale is very close to the mean transit time (4.8 years) for particles from the RSOW formation region to reach the exit at the Strait of Bab el Mandeb in the numerical experiment.
Original languageEnglish (US)
Pages (from-to)6542-6563
Number of pages22
Issue number9
StatePublished - 2015
Externally publishedYes

Bibliographical note

KAUST Repository Item: Exported on 2021-11-04
Acknowledged KAUST grant number(s): KSA 00011/02, USA 00002
Acknowledgements: Hydrographic and CFC-12/SF6 data can be accessed from authors. Other data used in this study are available in the following websites: sea surface temperature data at, Sea Surface Heat Flux at, QuikSCAT wind data at, and ASCAT wind data at work is supported by award (USA 00002, KSA 00011, and KSA 00011/02) made by King Abdullah University of Science and Technology (KAUST), National Science Foundation (OCE0927017), and WHOI Academic Program Office. We thank E. Gorman for measurement of the CFC-12 and SF6 samples. We thank Yasser Abualnaja, Elizabeth Bonk, Marshall Swartz, and Marti Jeglinski for helping with sampling of CFC-12 and SF6. We also thank two anonymous reviewers for their thoughtful and helpful reviews.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.


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