Field Study of Currents in the North of Strait Hormuz

Subject Areas : environmental management

Masoud Torabi Azad ¹ (Associate Prof. Faculty of Marine Science and Technology, Islamic Azad University, Tehran North Branch, Tehran, Iran.)
Samad hamzei ² (Ph.D Physical Oceanography, Islamic Azad University, Science and Research Branch, Tehran, Iran)

Received: 2014-02-28 Accepted : 2015-05-09 Published : 2016-03-20

Keywords: Current measuring, Tide, Wind driving currents, Density difference, Strait of Hormuz, Persian Gulf,

Abstract :

Introduction: In the northwestern part of Indian Ocean located Strait of Hormuz and has connected the Persian Gulf to the Oman Sea. Semi diurnal tides, seasonal winds, and buoyancy forces due to density differences waters of the Persian Gulf to the Oman Sea has caused water exchange in the Strait of Hormuz. Ocean currents are the major cause of environmental pollution, maritime transport, oil spills, and moving objects are floating in the Strait of Hormuz. The aim of this research was to study the currents in the northern Strait of Hormuz by Eulerian method to investigate the seasonal variation of currents in this Strait. Materials and Methods: The current survey by mechanical current meters with an                  accuracy ± 1 cm /s in the northern part of the Strait of Hormuz at interval time on January to May 2007 with total time duration of 8 days has been done. A mechanical current meter, flow meter and GPS were used in this monitoring. Mechanical current meter model A101 which was made ​​in England, was used. The device accurately measures speed 1 cm / s with an accuracy of 5 degrees, this system can record data every 5 minutes. Flowmeter Model Z30 is a very simple device that uses a blade, a few bars and wires, and a flow indicator is made.  It can measure up to 3.5 meters of water speed. By placing this device in the direction of water motion, water flow rate can be recorded. Discussion: The analysis of current data shows that semi diurnal tide is the main constituent. Hence this component was removed to consider the residual components due to wind and buoyancy typical deep tidal current is about 30-40 cm/s while the surface tidal current can reach 112 cm/s and the residual current range from 4.5-7.6 cm/s. In research Stations residual current magnitude in winter 5 cm /s is smaller than the spring rate 8 cm/s. Conclusion: The effect of tide on currents in the Strait of Hormuz at measurement stations has been shown. By moving from the center towards the north coasts of Strait of Hormuz, the speed of tidal currents will increase.  Residual currents are influenced by wind and density differences and moves from the north of Strait of Hormuz into the Persian Gulf. This current movement speed is lower in winter than in spring. Lardner and the monthly mean wind driven current and density gradient current was investigated for Persian Gulf and speed of currents close to the coast of Iran  at surface 0.05 m/s  to about 0.04 m/s in bottom was estimated.The results obtained of this research with compare the lardner and eta al model is correspond.

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