Investigation of Geostrophic and Ekman Surface Current Using Satellite Altimetry Observations and Surface Wind in Persian Gulf and Oman Sea

نویسندگان

1 Assistant Professor, Department of Surveying and Geomatics Engineering, Faculty of Engineering, University of Tehran, Iran

2 Ph.D. Student, Department of Surveying and Geomatics Engineering, Faculty of Engineering, University of Tehran, Iran

3 M.Sc. Student, Department of Surveying Engineering, faculty of Engineering, University of Zanjan, Zanjan, Iran

چکیده

The rise of satellite altimetry is a revolution in the ocean sciences. Due to its global coverage and its high resolution, altimetry classically outperforms in situ water level measurement. Ekman and geostrophic currents are large parts of the ocean’s current, playing a vital role in global climate variations. According to the classic oceanography, Ekman and geostrophic currents can be calculated through the pressure gradient force as well as the friction force assuming that the water’s density is constant. Investigation of Ekman and geostrophic currents existence along with the determination of their velocities can profoundly affect the various events of oceanography and different interactive processes between the atmosphere and the ocean. Additionally, the measurement of sea currents can be useful in determination of contamination transport, seawater exchange, fisheries, oil transfer, immigration of aquatic animals and several marine activities (e.g. military, telecommunication, fishing and research activities) and also has different effects on the regional climate. In the current study, local and climatic conditions, Ekman and geostrophic currents and their velocities have been investigated based on the solution of Ekman and geostrophic equilibrium equations in the region of the Persian Gulf and the Oman Sea. To this end, using data of Saral and Jeason-2 altimetry satellites and surface wind data measured by ASCAT satellite, velocities values of v and u as well as the value and the direction of Ekman and geostrophic currents were extracted in forms of monthly data. The results were compared with obtained measurements by AVISO and NOAA for the region of the Persian Gulf and the Oman Sea, and based on the obtained results of this study, the difference in the value of these currents is about 1 cm/s.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Geostrophic and Ekman Surface Current Using Satellite Altimetry Observations and Surface Wind in Persian Gulf and Oman Sea

نویسندگان [English]

  • Saeed Farzaneh 1
  • Kamal Parvazi 2
  • Tayebe Noroozi 3
1 Assistant Professor, Department of Surveying and Geomatics Engineering, Faculty of Engineering, University of Tehran, Iran
2 Ph.D. Student, Department of Surveying and Geomatics Engineering, Faculty of Engineering, University of Tehran, Iran
3 M.Sc. Student, Department of Surveying Engineering, faculty of Engineering, University of Zanjan, Zanjan, Iran
چکیده [English]

The rise of satellite altimetry is a revolution in the ocean sciences. Due to its global coverage and its high resolution, altimetry classically outperforms in situ water level measurement. Ekman and geostrophic currents are large parts of the ocean’s current, playing a vital role in global climate variations. According to the classic oceanography, Ekman and geostrophic currents can be calculated through the pressure gradient force as well as the friction force assuming that the water’s density is constant. Investigation of Ekman and geostrophic currents existence along with the determination of their velocities can profoundly affect the various events of oceanography and different interactive processes between the atmosphere and the ocean. Additionally, the measurement of sea currents can be useful in determination of contamination transport, seawater exchange, fisheries, oil transfer, immigration of aquatic animals and several marine activities (e.g. military, telecommunication, fishing and research activities) and also has different effects on the regional climate. In the current study, local and climatic conditions, Ekman and geostrophic currents and their velocities have been investigated based on the solution of Ekman and geostrophic equilibrium equations in the region of the Persian Gulf and the Oman Sea. To this end, using data of Saral and Jeason-2 altimetry satellites and surface wind data measured by ASCAT satellite, velocities values of v and u as well as the value and the direction of Ekman and geostrophic currents were extracted in forms of monthly data. The results were compared with obtained measurements by AVISO and NOAA for the region of the Persian Gulf and the Oman Sea, and based on the obtained results of this study, the difference in the value of these currents is about 1 cm/s.

کلیدواژه‌ها [English]

  • Ekman current؛ Geostrophic current؛ Surface wind؛ Wind stress
  • Satellite altimetry
Andersen, B., 2010, Satellite derived reference surfaces for surveying.Dtu-Space. Copenhagen. Denmark.
Aken, H. M. van, 2007, The Oceanic Thermohaline Circulation: An Introduction. Springer Science & Business Media.
Apel, J. R., 1990, Principle, of Ocean Physics. Academic Press, chp. 6.
AVISO, 2012, DT CorSSH and DT SLA Product Handbook - Aviso. France.
Bowditch, N., 2012, The American Practical Navigator. CreateSpace Independent Publishing Platform.
Dawe, J. T. and Thompson, L., 2006, Effect of ocean surface currents on wind stress, heat flux, and wind power input to the ocean. Geophys. Res. Lett., 33, L09604. doi:10.1029/2006GL025784.
Deng, X., Griffin, D. A., Ridgway, K., Church, J. A., Featherstone, W. E., White, N. J. and Cahill, M., 2011, Satellite Altimetry for Geodetic, Oceanographic, and Climate Studies in the Australian Region. In: Vignudelli, S., Kostianoy, A.G., Cipollini, P., Benveniste, J. (Eds.), Coastal Altimetry. Springer Berlin Heidelberg, 473–508.
Ekman, V. W., 1905, On the influence of the Earth’s rotation on ocean currents. Arkiv for Matematik, Astronomi, och Fysik, 2(11).
Fleet, D. J. and Weiss, Y., 2005, Optical Flow Estimation.
http://coastwatch.pifsc.noaa.gov.
http://oceanwatch.pifsc.noaa.gov.
Forman, M. G. G., 1998, Manual for tidal currents analysis and prediction, pacific marine science report. Podaac and Podaac Merged Gdr (Topex/Poseidon) Users Handbook. Jpl, D-11007, November.
Stewart, R. H. 2008, Introduction to physical oceanography, Department of Oceanography, Texas A & M University.
Lagerloef, G. S. E., Mitchum, G. T., Lukas, R. B. and and Niiler, P. P., 1999, Tropical Pacific near-surface currents estimated from altimeter, wind, and drifter data. J. Geophys. Res., 104(C10), 23, 313–23, 326, doi:10.1029/1999JC900197.
Munk, W. H., 1950, On the wind-driven ocean circulation. J. Meteorology, 7(2), 79–93.
Nansen, F. and Sverdrup, O. N., 1898, Farthest north: being a record of a voyage of exploration of the ship" Fram" 1893-96, and of a fifteen month's sleigh journey by Dr. Nansen and Lieut. Johannsen (Vol. 1). Harper & brothers.
Nitta, T. and Yamada, S., 1989, Recent warming of tropical sea surface temperature and its relationship to the Northern Hemisphere circulation. Journal of the Meteorological Society of Japan. Ser. II, 67(3), pp.375-383.
Reynolds, R. M., 1993, Physical Oceanography of the Gulf, Strait of Hormuz, and the Gulf of Oman--Results from the Mt Mitchell Expedition. Marine Pollution Bulletin, 27, 35-59, Printed in Great Britain.
Parvazi, K., Asgari, J., Amirisimkooei, A. R., and Tajfirooz, B., 2015, Determination of difference between datum and reference ellipsoid by using of analysis of altimetry data of Topex/Poseidon, Jason-1 and observations of coastal tide gauges, 5(1).
Picot, N., Case, K., Desai, S. and Vincent, P., 2003. AVISO and PODAAC user handbook. IGDR and. http://www.aviso.
Reynolds, R. W. and Smith, T. M., 1994, Improved global sea surface temperature analyses using optimum interpolation. J. Clim., 7, 929–948. doi:10.1175/1520-0442(1994)0072.0.CO;2
Scharffenberg, M. G. and Stammer, D., 2010, Seasonal variations of the large-scale geostrophic flow field and eddy kinetic energy inferred from the TOPEX/Poseidon and Jason-1 tandem mission data, J. Geophys. Res., 115, C02008, doi:10.1029/ 2008JC005242.1.
Shum, C. K. and Braun, A., 2004, Satellite Altimetry and Gravimetry. Lecture notes presented at Norwegian University of Science and Technology (NTNU), Trondheim, Norway, http://www.octas.statkart.
Stewart, R. H., 2009, Introduction to Physical Oceanography. Orange Grove Texts Plus, College Station, Tex.
Stommel, H., 1948, The westward intensification of wind-driven ocean currents. Transactions, American Geophysical Union, 29(2), 202–206.
Sverdrup, H. U., 1947, Wind-driven currents in a baroclinic ocean: with application to the equatorial currents of the eastern Pacific. Proceedings of the National Academy of Sciences, 33(11), 318–326.
Swift, S. A. and Bower, A. S., 2003, Formation and circulation of dense water in the Persian/Arabian Gulf. J. Geophys. Res., 108(C1), 3004, doi:10.1029/2002JC001360.
Vignudelli, S., Kostianoy, A., Cipollini, P., and Benveniste, J., 2011, Coastal Altimetry, Springer, German, Berlin.
Yelland, M. and Taylor, P. K., 1996, Wind stress measurements from the open ocean. J. Physical Oceanography, 26(4), 541–558.
Yelland, M. J., Moat, B. I. Taylor, P. K. Pascal, R. W. Hutchings, J. and Cornell, V. C., 1998, Wind stress measurements from the open ocean corrected for airflow distortion by the ship. Journal of Physical Oceanography, 28(7), 1511–1526.
Zonn, S., Kosarev, A. N., Glantz, M. and Kostianoy, A. G., 2010, The Caspian Sea Encyclopedia, 2010 edition. ed. Springer, Berlin; London.