Ocean Science www.ocean-sci.net 1812-0784 1812-0792 4 3 2008 10.5194/os-4-183-2008 http://www.ocean-sci.net/4/183/2008/ http://www.ocean-sci.net/4/183/2008/os-4-183-2008.html http://www.ocean-sci.net/4/183/2008/os-4-183-2008.pdf 183 198 2008-07-28 On the Indonesian Throughflow in the OCCAM 1/4 degree ocean model U. W. Humphries D. J. Webb david.webb@noc.soton.ac.uk King Monghut's Institute of Technology, Thailand National Oceanography Centre, Southampton SO14 3ZH, UK The Indonesian Throughflow is analysed in two runs of the OCCAM 1/4 degree global ocean model, one using monthly climatological winds and one using ECMWF analysed six-hourly winds for the period 1993 to 1998. The long-term model throughflow agrees with observations and the value predicted by Godfrey's Island Rule. The Island Rule has some skill in predicting the annual signal each year but is poor at predicting year to year and shorter term variations in the total flow, especially in El Niño years. <br><br> The spectra of transports in individual passages show significant differences between those connecting the region to the Pacific Ocean and those connecting with the Indian Ocean. On investigation we found that changes in the northern transports were strongly correlated with changes in the position of currents in the Celebes Sea and off Halmahera. Vertical profiles of transport are in reasonable agreement with observations but the model overestimates the near surface transport through the Lombok Strait and the dense overflow from the Pacific through the Lifamatola Strait into the deep Banda Sea. In both cases the crude representation of the passages by the model appears responsible. <br><br> In the north the model shows, as expected, that the largest transport is via the Makassar Strait. However this is less than expected and instead there is significant flow via the Halmahera Sea. If Godfrey's Island Rule is correct and the throughflow is forced by the northward flow between Australia and South America, then the Halmahers Sea route should be important. It is the most southerly route around New Guinea to the Indian Ocean and there is no apparent reason why the flow should go further north in order to pass through the Makassar Strait. The model result thus raises the question of why in reality the Makassar Strait route appears to dominate the throughflow. Arakawa, A.: Computational design for long-term numerical integration of the equations of fluid motion: Two-dimensional incompressible flow, J. Comput. Phys., 1, 119–143, 1966. Arief, D. and Murray, S. P: Low-frequency fluctuations in the Indonesian Throughflow through Lombok Strait, J. Geophys. Res., 101(C5), 12 455–12 464, 1996. Armi, L. and Williams, R.: The hydraulics of a stratified fluid flowing through a contraction, J. Fluid Mech., 251, 355–375, 1993. Bryan, K.: A numerical method for the study of the circulation of the world ocean, J. Comput. Phys., 4, 347–376, 1969. Bryden, H. L. and Beal, L. M.: Role of the Agulhas current in Indian ocean circulation and associated heat and freshwater fluxes, Deep-Sea Res., 48, 1821–1845, 2001. Cox, M. D.: A primitive equation 3-dimensional model of the ocean. Tech.Rep. 1, Geophysical Fluid Dyn. Lab, Natl. Oceanic and Atmos. Admin., Princeton Uni. Press, Princeton, N.J., 1984. Cresswell, G., Frische, A., Peterson J., and Quadfasel, D.: Circulation in the Timor Sea, J. Geophys. Res., 98, 14 379–14 389, 1993. Cresswell, G. R. and Luick J. L.: Current measurements in the Halmahera sea, J. Geophys. Res., 106, 13 945–13 951, 2001. Fieux, M., Molcard, R., and Ilahude, A. G.: Geostrophic transport of the Pacific-Indian Ocean throughflow, J. Geophys. Res., 101(C5), 12 421–12 432, 1996. Godfrey, J. S.: A Sverdrup model of the depth-integrated flow for the world ocean allowing for Island circulations, Geophys. Astro. Fluid, 45, 89–112, 1989. Godfrey, J. S.: The effect of the Indonesian Throughflow on ocean circulation and heat exchange with the atmosphere: A review, J. Geophys. Res., 101(C5), 12 217–12 237, 1996. Gordon, A. L.: Oceanography of the Indonesian Seas and their Throughflow, Oceanography, 18(4), 14–27, 2005. % %Gordon, A.L. and Susanto, R.D.: Makassar strait transport: Initial estimate based on arlindo results. Marine Technology Society Journal, 32, 34-45, 1998. Gordon, A. L., Susanto, R. D., and Ffield, A.: Throughflow within Makassar Strait, Geophys. Res. Lett., 26, 3325–3328, 1999. Griffies, S. M., Gnanadesikan, A., Dixon, K. W., Dunne, J. P., Gerdes, R., Harrison, M. J., Rosati, A., Russell, J. L., Samuels, B. L., Spelman, M. J., Winton, M., and Zhang, R.: Formulation of an ocean model for global climate simulations, Ocean Sci., 1, 45–79, 2005. Hellerman, S. and Rosenstein, M.: Normal monthly wind stress over the world ocean with error estimates, J. Phys. Oceanogr., 13, 1093–1104, 1983. Lee, T., Giering, R., and Cheng, B.: Adjoint sensitivity of Indonesian throughflow transport to wind stress: application to interannual variability, Jet Propulsion Laboratory Publication 01-11, 36 pp., 2001. Levitus, S.: Climatological atlas of the world ocean, NOAA Professional Paper No. 13, GFDL, Princeton University, NJ, 1982. Levitus, S. and Boyer, T. P.: World Ocean Atlas 1994, NOAA Atlas NESDIS, Vol. 4, Temperature, 117 pp., 1994a. Levitus, S., Burgett, R., and Boyer, T. P.: World Ocean Atlas 1994, NOAA Atlas NESDIS, Vol. 3, Salinity, 99 pp., 1994b. % %McCreary, J. P. and Lu, P.: Influence of the Indonesian Throughflow on the circulation of Pacific intermediate water. Journal of Physical Oceanography, 31, 932-942, 2001. Molcard, R., Ilahude, A. G., Fieux, M., Swallow, J. C., and Banjarnahor, J.: Low frequency variability of the currents in Indonesian Channels (Savu-Roti M1 and Roti-Ashmore Reef M2), Deep Sea Res., 41, 1643–1662, 1994. Molcard, R., Fieux, M., and Ilahude, A. G.: The Indo-Pacific Throughflow in the Timor Passage, J. Geophys. Res., 101, 12 411–12 420, 1996. Molcard, R., Fieux, M., and Syamsudin, F.: The Throughflow within Ombai strait, Deep-Sea Res., 48(5), 1237–1253, 2001. Murray, S. P. and Arief, D.: Throughflow into the Indian Ocean through the Lombok Strait, January 1985–January 1986, Nature, 333, 444–447, 1988. Murray, S. P., Arief, D., Kindle, J. C., and Hurlburt, H. E.: Characteristics of circulation in an Indonesian Archipelago Strait from hydrography, current measurements and modelling results, in: The Physical Oceanography of Sea Straits, edited by: Pratt, L., Kluwer Academic Publishers, Norwell, MA, 3–23, 1990. Meyers, G.: Variation of Indonesian throughflow and the El Niño-Southern Oscillation, J. Geophys. Res., 101, 12 255–12 263, 1996. Pacanowski, R. C. and Philander, S. G. H.: Parameterization of vertical mixing in numerical models of tropical oceans, J. Phys. Oceanogr., 11, 1443–1051, 1981. Pirani, A.: Testing Godfrey's Island Rule using the OCCAM model for the calculation of the Indonesian Throughflow, MSc Thesis, University of Southampton, 1999. Qu, Tangdong: Upper-Layer Circulation in the South China Sea, J. Phys. Oceanogr., 30, 1450–1460, 2000. Qu, Tangdong, Yan, Du, Meyers, G., Ishida, Akio, and Wang Dongxiao: Connecting the tropical Pacific with Indian Ocean through South China Sea. Geophys. Res. Lett., 32, L24609, doi:10.1029/2005GL024698, 2005. % %Schneider, N., Barnett, TP.: Indonesian Throughflow in a coupled general circulation model. Journal of Geophysical Research, 102(C6), 12341-12358, 1997. Semtner, A. J.: An oceanic general circulation model with bottom topography. Technical Report No. 9, Dept. of Meteorology, UCLA, Los Angeles, CA 90095, 1974. Siefridt, L. and Barnier, B.: Banque de Donnes AVIS Vent/flux: Climatologie des Analyses de Surface du CEPMMT, ORSTOM Report 91 1430 025, Toulouse, 1993. % %Susanto, R.D., Gordon, A.L., and Zheng, Q.N.: Upwelling along the coasts of Java and Sumatra and its relation to ENSO. Geophysical Research Letters, 28, 1599-1602, 2001. Susanto, R. D. and Gordon, A. L.: Velocity and transport of the Makassar Strait throughflow, J. Geophys. Res., 110, C01005, doi:10.1029/2004JC002425, 2005. Thompson, S. R.: Sills of the global ocean: a compilation, Ocean Model., 109, 7–9, 1995. Tozuka, Tomoki, Qu, Tangdong, and Yamagata, Toshio: Dramatic impact of the South China Sea on the Indonesian Throughflow, Geophys. Res. Lett., 34, L12612, doi:10.1029/2007GL030420, 2007. U.S. Naval Oceanographic Office and the U.S. Naval Ocean Research and Development Activity: DBDB5 (Digital Bathymetric Data Base-5 Minute Grid), U.S.N.O.O., Bay St. Louis, 1983. van Aken, H. M., Punjanan, J., and Saimima, S.: Physical aspects of the flushing of the East Indonesian basins, Neth. J. Sea Res., 22, 315–339, 1988. van Aken, H. M., Van Bennekom, A. J., Mook, W. G., and Postma, H.: Application of Munk’s abyssal recipes to tracer distributions in the deep waters of the southern Banda basin, Oceanologica Acta, 14(2), 151–162, 1991. Wajsowicz, R. C.: The circulation of the depth-integrated flow around an island with application to the Indonesian Throughflow, J. Phys. Oceanogr., 23, 1470–1484, 1993. Wajsowicz, R. C., Gordon, A. L., Ffield, A., and Susanto, R. D.: Estimating Transport in Makasar Strait, Deep-Sea Res. II, 50, 2163–2181, 2003. Webb, D. J.: A simple model of the effect of the Kerguelen Plateau on the strength of the Antarctic Circumpolar Current, Geophys. Astro. Fluid, 70, 57–84, 1993. Webb, D. J.: The vertical advection of momentum in Bryan-Cox-Semtner ocean general circulation models, J. Phys. Oceanogr., 25(12), 3186–3195, 1995. Webb, D. J., de Cuevas, B., and Richmond, C.: Improved advection schemes for ocean models, J. Atmos. Ocean. Tech., 15, 1171–1187, 1998a. Webb, D. J., de Cuevas, B. A., and Coward, A. C.: The first main run of the OCCAM global ocean model, Internal Report of James Rennell Divesion, Southampton Oceanography Centre, UK., 1998b. Wolanski, E., Ridd, P., and Inoue, M.: Currents through Torres Strait, J. Phys. Oceanogr., 18, 1535–1545, 1988. Wyrtki, K.: NAGA Report, Vol. 2, Scientific results of marine investigations of the South China sea and the Gulf of Thailand 1959–1961, Physical Oceanography of the Southeast Asian Water, Scripps Institution of Oceanography, 195 pp., 1961.