HYDROPHYSICS
Year:2016 | Volume:1 | Issue:1 |Papers Count:6

In this research, the variability in temperature and salinity field of the Caspian Sea was studied using POM model. In this model, temperature and salinity field’s data and wind field and the flux of atmospheric data were collected from WOA and ECMWF, respectively, with a resolution of 7.5 minutes and the time step of 6 hours and for Bathymetry data from GEBCO08 with an spatial resolution of 30 seconds is used. Initially, the model for ten years (1988-1997) was carried out. After examining the stability of the output with observation data available (1996) were compared, that good agreement between their temperature and salinity changes observed. The results showed, the maximum monthly average surface temperature difference of the Caspian Sea in February, May, August and November are 18°C, 13°C, 11°C, 20°C, respectively and the maximum monthly average surface salinity difference are, 2.8 psu, 3.2 psu, 5.2 psu and 4.8 psu, respectively. Salinity gradient in depth in February and August in the western part of the Caspian Sea to the eastern part has been stronger. Surface temperature difference between the eastern and western part of the middle basin, in August, and its temperature profile indicates the upwelling phenomena in this part of the Caspian Sea.

This paper investigates the spatial and temporal changes of water physical parameters in the Strait of Hormuz. Temperature, salinity, and density measured and investigated for winter 2012, spring and summer 2013 by using CTD probe. Moreover, different water masses and layers were studied. The whole water column thermally, at most stations were completely mixed in the winter. Surface layer, namely mixed layer, is completely homogeneous in summer. Spring time is a transition state of water properties between winter and summer. Maximum changes of water column density were 2.0, 4.25, and 5.0 for winter, spring and summer, respectively. Water volume of Persian Gulf outflow change seasonally and sometimes Persian Gulf outflow was traceable near Iranian coast in spring. Based on this research, it seems that Persian Gulf outflow water volume was maxima in the spring time. Study of water masses in different parts of the Strait of Hormuz shows two different water masses in the eastern part of the strait. In summer, only two separate water masses were traceable in the central and western part of the Strait. It was also evident that, there were three-layers in the water column in summer. At the interface of water masses, fronts of different strengths depending on temperature and salinity gradients were formed. Salinity and sigma-t of Persian Gulf outflow in summer were more than those of winter.

The marine is a dynamic and continuously changing environment with many phenomena that have specific characteristics. In this study, the mathematical methods such as cross-spectral analysis and Rotary spectrum analysis and calculation have been made using moored acoustic Doppler current profiler data from the Straits of Hormuz during the period December 1996 to March 1998.The results showed that the highest peak energy domains occur in the four-month, diurnal, semidiurnal and 21 days phenomenon. In order to study the temporal variation characteristics of the current at the mooring station, we calculated the current fluctuations from 10 to 101m levels by using the cross-spectral analysis and Rotary spectrum analysis methods.

This study represented results of the in-situ measurements of flow in the Karun River for a period of one-month length in the spring season. The measurements were carried out in a station with average depth of 5 m, located approximately 120km distance from the northern head of the Persian Gulf. It was aimed to improve our understanding of flow hydrodynamics in the Karun River. Spectral analysis of current showed a high energy in tidal frequencies which represent the tidal influence on this station. Unexpected, results from the field work show that the the maximum measured flow was 70.6 cm/s in seaward direction, coincidence with neap tide. It was due to the high level of river discharge. In this period, the most important reasons for the change flow direction were identified to be tide and river discharge fluctuation .Also, it is worth to mention that Harmonic Analysis of water level varations introduces M2, K1and O1 as the main tidal constituents with dominant of semi-diurnal tide at the location of observation.

This work is devoted to present the results of an ensemble prediction system developed for the Weather Research and Forecasting (WRF) model to predict surface wind over the Persian Gulf. To construct the ensemble members a combination of perturbed initial condition (using Monte Carlo method) and model perturbations (using multi physical parameterization schemes) is employed. Here, an ensemble prediction system with 15 members (three physical parameterization schemes and five initial condition perturbations for each one) is used to generate the surface wind and other meteorological field predictions over the Persian Gulf. Assessment of the ensemble mean against the observational in situ and satellite (e.g., ASCAT and QuikSCAT) data indicates promising performance of the ensemble prediction system over the deterministic predictions.

The ocean mixed layer (OML) is a quite turbulent area of the upper layer of the ocean, that is bound from above by air-sea interaction and limited from below by warm water masses that are dynamically stable. Surface buoyancy and wind are sources turbulence in the mixed layer. Since the ocean mixed layer plays an important role in the military industries, oil industry and in the long-term climate change, then recognition characteristics of OML is necessary. In this study, using the Navier-Stokes equations and adapting the PALM (Parallelized Large Eddy Simulation) model equations, also using Large Eddy Simulation method, LES, and clustering (parallelism) to calculate changes has been mixed layer. PALM is a model that for the study of turbulent fluids with high Reynolds numbers like atmosphere and ocean, taking into account the appropriate and accurate boundary conditions. Using this model for the Persian Gulf Latitude, temperature difference between ocean and atmosphere and wind stress produce free and forced convections respectively. Model outputs show variability in the pattern of circulation and mixing during the different seasons. These variabilities can play an important role in the oil pollutions, climate change and other change in the global ocean.