Aziz Abdollahi - M. Sc. student, Department of Marine Physics, Faculty of Natural Resources and Marine Sciences, Tarbiat Modarres University, Mazandaran, Iran
Somayeh Nahavandian - Assistant Professor, Department of Marine Physics, Faculty of Natural Resources and Marine Sciences, Tarbiat Modarres University, Mazandaran, Iran
Dariush Mansouri - Assistant Professor, Department of Marine Physics, Faculty of Natural Resources and Marine Sciences, Tarbiat Modarres University, Mazandaran, Iran

In this research, the seasonal and spatial variations of temperature and the depth of different layers of water vertical structure in Noshahr and Lavij Rood during spring and autumn in 2012were studied. Field measurements were carried out using a CTD up to a depth of 70 meters. Based on the analysis of field data, three layers of mixed layer, thermocline, and deep layer in the spring can be clearly distinguished, while in the autumn, the deep layer was not observed in the range of measured depth. In the spring, the mixed layer was expanded to a depth of 10 m, the temperature of 21.5-22.5 ℃ and a thermocline depth of 10-45 m, a temperature of 8- 21.5 ℃, and followed by a deep layer. In autumn, the depth of the mixed layer was up to 40 meters with the temperature of 20-20.5 ℃, and the thermocline was observed in the depth of 40- 60 meters and the temperature ranges from 14-20 ℃. The results showed an increase in the depth of mixed layer and thermocline layer and therefore an enhancement in the temperature for the layers in the autumn compared with the spring. Also, the spatial comparison of the temperature profile in the spring indicated the deepening of the depth of the mixed layer in the Noshahr region relative to the Lavij Rood, while in autumn, these spatial changes were insignificant. The probable causes of these seasonal and spatial differences are investigated and discussed.

Vertical Water Structure, Mixed layer, Thermocline, Caspian Sea, Noshahr, Lavij Rood