عنوان مقاله [English]
نویسندگان [English]چکیده [English]
In this research, the large-scale currents have been investigated using field data of the Caspian Sea temperature, salinity and density at the stations near west of the South Caspian, related to two field patrols. The geostrophic current is created due to the balance of the gradient pressure force and theCoriolisEffect, and is the major factor in the creation of large-scale currents. After analyzing the data, the speed and direction of these types of currents were calculated using satellite imagery.These images were extracted from Aviso satellite with a spatial resolution 0.25 degrees.The calculations for the five vertical sections in the westpart of the South Caspian Sea werecarried out using Excel software and the depth profile of the geostrophic currents speed was obtained speed in each of these sections.In the Southwestern part of theCaspian, the average velocity of these currents for field data was calculated to be 5.85 and 15 cm /s is for the summer and winter respectively. The direction of these currents was also obtained to be 285 in the summer and 44 in the winter. With regard to the satellite images, counterclockwise currents up to 4.5 cm/s velocities and, eastward counterclockwise currents at the velocities of 8 cm/s are observed in the summer and in the winter respectively. The value of the currents velocity (the magnitude of the vectors) indicates that the average currentsvelocity is higher in the winter. One of the reason for this is due to the difference in density caused by the increase in rivers flow rate (especially the Volga), precipitation, wind, etc.