دکتر مریم سیوف جهرمی

Strait of Hormuz is a valuable waterway in economic, political, military, scientific and fishery terms. In general, its depth increases from west to east and north to south. Some trenches are located in it, which are very obscure, and each of those trenches has its own unique and special conditions that needs more studies. One of the largest trenches in Iranian waters is situated in the western part of the Strait of Hormuz and the south of Greater Tunb Island. In the current research, the physical characteristics of this trench, including temperature, salinity, and sound speed, have been studied using the seasonal data of the field measurement of the Persian Gulf Explorer in 2018 . Temperature and salinity data were directly measured by using the Conductivity Temperature Depth (hear after CTD) probe. The sound speed was calculated by modifying the programming codes of the library function of the sound speed of sea water. The results clearly show that, the water column has three layers in spring and summer in terms of temperature, all three layers of mixed, thermocline and deep layers are observed. But in autumn and winter, the water column becomes one single layer and well mixed. Also, in terms of salinity, the water column has three layers in all seasons. There are the warmest waters in the depths of the trapped waters. Furthermore, the highest speed of sound has been measured in autumn and the highest concentration of salinity has been measured in winter. The salinity in the depths of the trench reaches more than 41 psu, which is more than the outflow of Persian Gulf Water in the Strait of Hormuz. In other words, the salinity of more than 40 psu is not only specific to the outflow of the Persian Gulf in the Strait of Hormuz, and this high salinity can also be observed in the trapped waters of the Strait of Hormuz, which certainly affects the biological species present in these depths. The speed of sound in spring and summer follows the temperature. The pattern of sound speed in autumn and winter is more dependent on salinity. The sound channel is formed in the two seasons of spring and summer in the depth range of 20 and 40 meters, respectively, which shows the importance of the seasonal thermocline layer in a suitable place for the hiding place of subsurface floats and submarines or even military divers.

The Persian Gulf is a semi-closed sea that leads to the Gulf of Oman and open waters through the Strait of Hormuz. the main inflow is the Indian Ocean Surface Water (IOSW), which after circulating in the Persian Gulf, Persian Gulf Water (PGW) is created. It was used 11 stations of a valid data set, temperature and salinity, of wintertime ROPME1992 Crouse, which was prepared from the National Oceanographic Research Institute to investigated temperature and salinity changes by measurements and density, sound speed, and water column stability changes caused by software calculations (Ocean Data View) due to the inflow and outflow of Persian Gulf. The measured stations started from Iranian Waters (Lavan Island) and continued until the United Arab Emirates (Sir Bani Yas Island). The results showed water temperature changes in winter between 17.56°C and 20.25°C, salinity changes from 38.48 psu to 43.93 psu, potential density anomaly changes from 27.47 kg/m3 to 19.32 kg/m3 and the changes of sound speed are 1521.7 m/s to 1528 m/s. Southern shallow waters have lower temperature, higher salinity and density. In density changes, the role of salinity is greater than temperature, but in the changes of sound speed, temperature has a greater contribution in the north of the Persian Gulf and in the south of it, salinity has a greater contribution. The highest speed of sound is related to the north and the lowest is related to the middle and south of the Persian Gulf. Near the coasts of Iran, at the depth more than 30 meters, a subsurface flow of warm water is observed, which is not affected by the surface layers that have cooled in winter, and still has the effected by Indian Ocean Surface Water (IOSW). The presence of CE1 eddy, at station 4, at a depth of about 30 meters is completely visible, which is due to the return of the IOSW flow. Although the water column from station 5 to 9 is mixed and relatively homogeneous, it is horizontally heterogeneous. Also, the results clearly show that the two different flow of IOSW (in the north) and PGW (in the south) cause different water column stability regimes, so that in the northern stations, the diffusive regime and in the southern stations, the finger regime plays a greater role in creating double diffusion convection. In the southern stations, layers consisting of static instability are seen more than layers consisting of double diffusion convection in the water column. In conclusion, the diffusive regime generally plays a greater role in creating double diffusion convection in this cross section of The Persian Gulf in winter.

The Persian Gulf is a semi-enclosed water basin that is utilized by various countries, and its territorial waters are not exclusive to Iran. Past studies have largely overlooked the distribution of temperature and salinity in the Iranian section of the Persian Gulf. This research investigates the characteristics of temperature and salinity in this region. The data used in this study consists of CTD temperature and salinity measurements collected during the Persian Gulf Explorer expedition in May 2019. Ten stations were selected, and the data were divided into two sections: eastern and western parts of Iran’s territorial waters, and then analyzed using ODV software. The results indicate that at stations perpendicular to the Iranian coast, the water column down to the deepest measured depth exhibits stratification and well-defined baroclinic conditions from the Iranian coast to the mid-waters of the Persian Gulf. This stratification is influenced by a counterclockwise eddy resulting from the inflow of Indian Ocean Surface Water (IOSW). The inflow velocity gradually decreases as it enters the Persian Gulf, leading to horizontal instability that can induce upwelling. Notably, upwelling is observed at station 7, where at depths exceeding 50 meters, the minimum temperature (20.57 °C) and salinity (approximately 40 psu) are recorded, indicating the rising of deeper water.

Changes in temperature and salinity in the water column, sea water always faces phenomena such as inversion of temperature and salinity and changes in layering and instability. Strait of Hormuz, which is the place of water exchange between the Persian Gulf and the Gulf of Oman, due to the interaction of water masses, has the ability of double diffusion convection and change in water stratification. The area studied in this research is east of the Strait of Hormuz and west of the Gulf of Oman. The data used are the temperature and salinity data obtained from the ROPME2006 cruise in 21 stations, which were first filtered in the Excel software. The data were divided into 7 equal stations in three sections: northern, middle and southern sections. Then graphs were drawn and analyzed with the ODV software package,. The maximum frequency of buoyancy increases while moving from northern to southern waters, and its minimum decreases. In other words, it can be said that the most stable and unstable layers are observed in the southern section. Static instability can be seen in northern waters up to a depth of 53 meters and in the middle and southern waters up to the last measured depth. In the northern and middle waters up to the last measured depth of the finger regime and in the southern waters up to a depth of 120 meters and below it to the last measured depth, the diffusion regime has a greater contribution in creating double diffusion convection.

Sea surface temperature is an important parameter in oceanography and marine measurements. Also, chlorophyll-a is another parameter that affect the biotic and abiotic characteristics of marine areas. The present study was carried out with the aim of investigating changes in sea surface temperature, in relation to the creation, dispersion and distribution of chlorophyll a in Jask port. In order to achieve the mentioned goal, the MODIS satellite images were used during a 21-year period (2000-2020) for different seasons. Average values of both parameters were calculated for 21 years seasonally and annually and for the whole region, and their relationship through Pearson's correlation coefficient. According to the sea surface temperature distribution, the parts near the coast and the western regions of the study area have higher temperatures than other regions, which is probably due to the human activities in the coastal areas. Results also show that the average sea surface temperature changes over time. On the other hand, based on the maps extracted from the chlorophyll a concentration, in terms of spatial distribution, the highest amount of chlorophyll-a is in the coastal and adjacent areas, so that the highest amount of chlorophyll-a is found in the southern coasts of Sistan and Baluchestan province, Chabahar region, and also the western parts of Hormozgan province. The results related to chlorophyll well show the presence of coastal upwelling in the northern part of Makran coast. In general, the distribution of chlorophyll-a in the studied area is higher in cold seasons than in hot and warm seasons. Correlation relationship between changes in sea surface temperature and chlorophyll-a concentration shows that there is negative correlation in autumn and winter and positive correlation in summer and spring. In this study, by examining the maps of chlorophyll-a concentration in different seasons, clockwise circulations of chlorophyll-a changes were observed in the studied area, which can be a proof of the occurrence of upwelling in this area. To investigate the phenomenon of coastal upwelling, it should be noted that the occurrence of this phenomenon is due to wind leading to Ekman transport, and hence, the change in surface water temperature. As a result, a change in sea surface temperature or a change in sea level can be a secondary cause of the upwelling phenomenon. The results showed that in the studied area, fluctuations related to the increase or decrease of SST do not have much effect on the amount of changes in the concentration of chlorophyll-a, and the only observed correlation between SST and chlorophyll-a was observed in the fall season, and this correlation was negative. So that in this season, following the increase in the average SST, the concentration of chlorophyll-a decreases.

The Makran water basin includes the Gulf of Oman and part of the Arabian Sea, which is adjacent to the Indian Ocean.In this study, the surface temperature, salinity and density and vertical cross section of them related to a part of the Makran water basin(56.425-66.126°E;23.375-25.80°N)have been investigated.For this purpose, the World Ocean Atlas data set (2018) related to the National Oceanic and Atmospheric Organization of NOAA (abbreviated as WOA18) with the resolution of a quarter of a degree of latitude have been used as seasonal and annual averages.Using ArcGIS software, surface maps were plotted, and using Surfer software, cross-section maps were also illustrated, and vertical average profiles were plotted with the Grapher software as seasonally and annually averages. Sea Surface maps were contoured by spline interpolation. Cross-sectional maps were created from the surface to the depth of 2000 meters by the intervals of two degrees of latitude(four transects in total) and the distance between the grid station points was completed using IDW interpolation.The results show that density changes are largely dependent on salinity changes directly and temperature changes inversely.Seasonal and spatial changes of quantities are evident in Makran water basin. Also, the cross-sections show that the thermocline and halocline changes are dependent on each other and have a direct effect on the pycnocline changes. An increase in temperature causes a decrease in density, and an increase in salinity causes an increase in density, and as a result, the heavy layer falls down from the surface to a deeper part.Also, a significant difference in salinity can be seen in the west due to the presence of the Persian Gulf water mass (PGW) and in the east due to the river entrances and the occurrence of summer-time monsoon on this basin. Although the average annual sea surface density of Makran water basin is 24.5kg m-3, but its value decreases in the warm and rainy summer season. Moreover, the west of the Gulf of Oman is warmer and saltier than the east and shallow areas experience more temperature stress than the middle of the basin, which is deeper. In addition, the mixed layer (especially from the surface to a depth of 30 meters) is strongly affected by seasonal changes, and the difference between the warm summer season and the cool winter season can be seen well in the vertical profiles of the Makran water basin. The presence of the Persian Gulf water mass can be seen at a depth of 250 to 400 meters. In the deep layers with the depth of more than 1000 meters, the temperature has insignificant seasonal changes; but it decreases sharply and reaches a temperature of 4°C.The density also increases strongly and reaches more than 33 kg m-3.

Coral reefs are one of the most important and diverse marine ecosystems that provide many benefits to humans. The increase in the sea surface temperature (SST), leads to their biology disruption and bleaching. In the present study, the relationship between the increase in SST due to climate change and the interactions between genes and proteins has been investigated. The results can give us a perspective on the extent of the vulnerability of corals to stress and the adoption of methods to protect them. Data on SST anomalies in the Persian Gulf was obtained using satellite data. The metabolic pathway of sod and cat genes in oxidative stress, and hsp90 gene in heat shock pathways were obtained by KEGG. Gene and protein interactions were obtained through GeneMANIA and STRING databases respectively. SST analyzes showed that there are temperature fluctuations in the Persian Gulf from the lowest temperature, about 16 °C to about 35 °C in Khark Island. Therefore, the coral reefs of the Persian Gulf tolerate very high temperatures. During thermal stress, the coral host responds to oxidative stress by regulating the expression of antioxidant genes, including sod and cat, to protect the coral-algae symbiosis. In addition, the expression of hsp90 indicates its role in protecting proteins from heat damage. Understanding the relationship between SST and the molecular health status of coral reefs is essential to develop conservation strategies to protect these marine ecosystems in the face of climate change.

The Gulf of Oman, with an area of about 94000 km2 and a maximum depth of more than 3000 m, is located between latitudes 22 and 26 degrees of north and longitudes 56 and 62 degrees of east. This gulf plays the role of a waterway that connects the Persian Gulf to the Indian Ocean and is the place where the saline water of the Persian Gulf is exchanged with the less salty water of the Indian Ocean. This research aims to investigate the Persian Gulf Water mass (abbreviated as PGW) in the Gulf of Oman and investigate its seasonal changes.

In order to identify PGW, in the studied area, the international temperature and salinity data set of the World Ocean Atlas with the abbreviation WOA18 and the spatial accuracy of 0.25° longitude and latitude at the depths of zero, 150 and 300 meters were used seasonally. The surface maps were ploted for the mentioned depths in Ocea Data View (ODV) software. A vertical cross section map was also illustrated in the middle of the Gulf of Oman to determine the thickness of the PGW, the extent of its expansion, and the depth of its placement (based on the salinity line of 36.45 psu).

The results show that the density on the surface is mostly a function of temperature. Winter is the coldest (23.24˚C) and densest (25.12 kg/m3) season and summer is the warmest (32.42˚C) and least dense (22.41 kg/m3) season in the surface layer. Summer experiences the highest and lowest salinity at the surface (36.45 psu<ssurface<36.66 psu) and at a depth of 150 m (36.12 psu<s150 m<36.45 psu). On the contrary of the surface layer, where winter is a cold season and summer is the hot season, at the depth of 150 m, summer is the cold season and winter is the hot season, which can be attributed to the differences of the seasonal thermocline up to the depth of 150 m. At the depth of 150 m, the density pattern in summer and autumn is a function of salinity, but in spring and winter, the density pattern is a function of temperature. In addition, in summer, sub-mesoscale high-pressure cyclones near Muscat can be seen on the surface, which are not clearly seen in other seasons. Also, the results clearly show that PGW is not seen in the surface layer and flows subsurface from the southern side of the Strait of Hormuz towards the Gulf of Oman. The depth of placement and extent of PGW has seasonal and spatial changes, and by moving eastward in all seasons, the thickness of PGW decreases due to mixing with the surrounding waters. The results obtained from the vertical cross section AB, in the middle of the bay, show that PGW is observed during different seasons from the depth of 150 to 375 meters, which is shallower in spring and summer and has less depth buoyancy than in autumn and winter.</s</s
In the side results of this research, several fronts such as Ras Al-Had, Fins and Al-Ramis were observed in the quantity of temperature, salinity or density, which had seasonal changes. These fronts were especially noticeable in layers such as 150 m and 300 m depth because the existence of subsurface fronts is less reported in the region. Also, the results of the research showed dense and less dense cores, some of which are formed due to the eddies in the area and others due to the hydrodynamics of the area. For example, the low salinity core (13.36 psu) near Chabahar can be due to the occurrence of the upwelling of the area, which brings the less saline waters of the middle of the gulf to the surface and causes a decrease in salinity.

The results of this research clearly showed that PGW has seasonal changes and is located at shallower depths in spring and summer than autumn and winter. Examining the same surface maps, especially at the depth of 150 m, showed that PGW, in addition to the southern coast, can also be seen on the northern coast, which requires a more detailed investigation regarding the possibility of its presence on the northern coast or its multiple branches.

In this research, satellite has been used for the purpose of identifying and finding the waters of the PersianGulf in the Sea of Oman.Finding the subsurface water exiting the PersianGulf through the cross of the Strait of Hormuz by identifying the temperature characteristics of Oman's surface water in the area where the presence of subsurface water in the Persian Gulf has been confirmed in previous studies can lead to finding the subsurface water.In this study, the sea surface temperature data of OSTIA for the studied basin, which is the Persian Gulf and a part of the Oman Sea(47 to59.45degrees of east and 22.60 to 32 degrees of north)was prepared.Then, according to the studies based on the73-year measurement data available in the region and identifying the temperature range of the surface water of the Oman Sea(22.20-23.00C) and the subsurface water of the Persian Gulf(16.00-22.20C)superimposed on each other, the satellite data were filtered. In order to filter the data and draw the figures, it was used coding in MATLAB environment.The results show that the water of the Persian Gulf can be transported to the middle parts of the Oman Sea, surface water (temperature 28.5 to 30 degrees of centigrade)in the cold season in the range of58.5to59degrees of east and in the warm season it advances towards the longitudes up to 59.5 degrees of east.As a result, the infiltration rate of Persian Gulf water in the Oman Sea in the warm season is half a degree of longitude more than the cold season.

Identifying shallow water masses is much more complex than deep water; because physical and chemical changes in shallow water occur faster and the properties of the water mass are lost. Since in the absence of air-sea interaction, water masses have different properties, so in this study, due to temperature and salinity conservation, the properties of Persian Gulf water mass are identified. One of the main characteristics of the Persian Gulf is its very shallow depth with an average depth of 35 meters. The maximum depth is located in the Strait of Hormuz with a depth of about 100 meters. The Strait of Hormuz is located in the northwestern part of the Indian Ocean and is the junction of the Persian Gulf with the Sea of Oman.

In this research, a 3D open source ocean model FVCOM in 20 layers was used to model the water exchange between the Persian Gulf and Sea of Oman (47˚E to 59.45˚E and 22˚N to 32˚N) without considering the wind stress on the region, the flow pattern of Persian and Oman Gulfs and the water mass of Persian Gulf in the four seasons of spring, summer, fall and winter should be studied. FVCOM uses the finite volume method to discretize hydrodynamic equations in a triangular grid. Specialized SMS software version 10 was used to generate the computational network. A non-uniform computational network with a horizontal resolution of at least 950 m to 4700 m was used in the model and the bathymetery information was interpolated with 30-second accuracy from the GEBCO-2019 data on this network. Water level fluctuations on open boundaries correspond to the location of the open boundary nodes of the computational network located at 59.45˚E, which was extracted from the TMD and entered as the main configuration of the model. Temperatures and salinities profiles of open boundaries from HYCOM model output (freely available) were also used at standard depths. The model was run in the absence of air-sea interaction and the role of wind stress for 6 years. HYCOM and satellite data were used to calibrate and validate the model, respectively.

The saline waters of the Persian Gulf to the mouth of the Strait of Hormuz are well visible in the surface layers and are not seen in the surface layers from the mouth of the Persian Gulf to the Sea of Oman. In the middle layers of the Oman Sea, there are waters with the characteristics of the waters of the Persian Gulf, which can be concluded that the surface waters that existed in the west of the Strait of Hormuz have been transferred to the lower or middle layers and flowed to the Oman Sea. Considering the temperature and salinity conservation in the water mass, the temperature and salinity of the Persian Gulf in the Strait of Hormuz were studied and the results show that the Persian Gulf water mass (38psu) in the summer season through the south of the Strait of Hormuz as a subsurface flow and in the winter season this water mass penetrates to greater depths and moves further away from the Strait of Hormuz. The Persian Gulf water mass exits through the southern part of the Strait of Hormuz as a subsurface flow. In the summer season, there is a water mass with 37psu salinity in the depth range of 50 to 80 meters and 40 km off the coast of Oman, whose exact position is latitude 25.4˚N and longitude is 56.50˚E to 56.69˚E and in the cold season, it moves away from this area and advances to lengths greater than 57˚E and penetrates to a depth of about 130 to 150 meters and more depths.

Due to the high rate of evaporation in the Persian Gulf, to replace the evaporated waters of the Persian Gulf, it is necessary for water to enter the Persian Gulf from the Strait of Hormuz. The salinity results of summer show this phenomenon well and the water entering the Persian Gulf is diverted to the coast of Iran and the movement of these waters from the coast of Iran to the northwest of the Persian Gulf continues. There are years, but it is more intense in summer than in other seasons.

Geostrophic currents profoundly influence various oceanographic events and different interactive processes between the atmosphere and the ocean. According to satellite images, eddies of Persian Gulf with an average diameter of 40-90 km and a speed of 3-6 cm/s, have been observed mostly near the coasts of Bushehr and the central part of the Persian Gulf. Hence, by the purpose of numerical solution, a geostrophic eddy current is dissolved in one layer fluid model called the shallow water model.

The present study uses numerical solutions for geostrophic equations provided by the Woods Hole Oceanographic Institution, entitled "Coriolis Guide" by James F. Price and is available in four separate sections for free research studies. It can cover basic equations based on the Coriolis force (such as the geostrophic equations). Using dynamic realities such as ocean shallowness, hydrostatic approximation, and the relatively constant nature of the vertical structure of the ocean, a geostrophic eddy is solved in MATLAB software based on the geostrophic equations. The origin of the coordinate system is on the center of the eddy and the results are plotted along the diameter of the eddy. The Coriolis parameter, f, is constant (f-plane coordinate system) and the friction is ignored. In this numerical solution, the finite difference numerical method has been used and the model development has been done on a structured grid and regular rectangular shape. The studies have been performed at latitude 28˚N (similar to the Persian Gulf) for a geostrophic eddy with a width of 50 km and a peak height of 3 m relative to its sides. In this numerical solution, the eddy properties of the Persian Gulf are tested as much as possible. The simulation is performed as a dense layer of fluid with a rectangular peak for 10 days from the initial time of zero and from a standstill (initial velocity of zero in the center of the peak). The energy source for the eddy activity is provided by the potential energy stored in the initial stationary state of the fluid package. Therefore, the total energy is stored in this shallow water model.

The Rossby deformation radius was 28.5 km and eddy velocity was 0.029 m/s, which was in good agreement with the satellite images of previous studies. The results show that due to the approximation of the geostrophic current, the resulting eddy shape is symmetrical and Gaussian. The eddy peak begins to fall by the release of the initial rectangular peak, at zero time for a few seconds under gravity at the beginning of the simulation, and it releases potential energy and produces a current. The current moves at a constant speed in the eddy. Moreover, at the beginning of the simulation, many instabilities are observed on the water surface and around the main geostrophic ring, which as the end of the simulation approaches, these pulses almost disappear and only the main geostrophic ring of eddy remains relatively stable. In addition, the initial rectangular eddy becomes a soft curved eddy. The results show well the two opposite directions of (horizontal components of) velocities at the right and left of the center of the geostrophic eddy. By shifting along the current due to the right and left of the geostrophic eddy ring relative to its center, a vortex is created that creates rotation for a balanced geostrophic eddy. Kinetic energy and potential energy will be equal on the last day of the simulation when the model reaches a steady state and perturbations on the basin surface disappear.

From the results, it can be clearly seen that the Coriolis force and gravity lead to an eddy with a geostrophic equilibrium. By changing the vertical intensity of the fluid column strength, the rotation speed of the eddy also changes, and the larger eddy diameters have more energy.

In this study, sea level anomaly of Persian Gulf (spatial resolution of 0.25 degrees of latitudes and longitudes) was investigated in the MATLAB software environment by using long-term AVISO data for 25 years (1 January 1993 to 31 December 2017). The 25-year average of the data shows that the sea level anomaly is positive and equals 3.06 ± 0.05 cm (mean± standard deviation), which is higher than the global average. Its range varies from a minimum of 2.46 cm to a maximum of 3.42 cm. The 25-year average of each season illustrates that sea level anomalies face a rise in autumn and a fall in spring. The two seasons of summer and winter are transition seasons from the maximum anomaly of autumn to the minimum anomaly of spring. The results also show that the spatial distribution of sea level anomaly in the basin is different. The mean sea level anomaly trend in the Persian Gulf is +2.9±0.1 mm/year, which practically divides Persian Gulf in the three parts of northwestern parts near the Arabian coast (anomalies less than 2.5 mm/year), the northern and central parts of the gulf (anomalies of 2.5-5.5 mm/year) and the southern part of the gulf and Strait of Hormuz (anomalies more than 3.5 mm/year). Therefore, although the head of Persian Gulf has positive trend changes, it is less than its southern part and near the Strait of Hormuz. If the Persian Gulf Sea level continues to rise, over the next 200 years, the Persian Gulf sea level will rise more than 0.5 m, with significant changes in the size and area of the basin.

The Persian Gulf is a shallow, semi-closed environment with an average depth of 35 meters and a maximum depth of 90 meters, connected to the Gulf of Oman through the Strait of Hormuz. The Persian Gulf is one of the main sources of saline water masses in the world. In the past, passive detectors have been used to track water mass. The use of satellite data in the study of water patterns and masses is a new science. The reasons of satellite data usage are its low costs and its availability. The purpose of this research is to investigate the location of Persian Gulf Water mass (PGW) in both warm and cold seasons which by using satellite data analysis, the distribution and dynamics of the Persian Gulf Water mass have been investigated and its possible areas in the Oman Sea have been identified.

The sea surface temperature of the studied area (47.00-59.45˚E, 22.60-32.00˚N) prepared from the Group for High Resoulation Sea Surface Temperature (SST) of NOAA named OSTIA (by the resolution of 0.05˚), and Sea Surface Salinity (SSS) prepared from NOAA NESDIS STAR (by the resolution of 0.25˚), respectively. First, daily statistical data for six years (2014-2019) were extracted annually, in both warm and cold seasons. Then, temporal mean, maximum, minimum, range and standard deviation were obtained for the whole basin and the means of the basin were illustrated separately for each season. The spatial mean of annual SST of basin in the studied years (2014-2019) was calculated for all cells, but the spatial mean of annual SSS was not calculated due to the lack of data in many cells. Then, the SST and SSS satellite data, according to the 73-years measured historical data, were spatially filtered in MATLAB to obtain the filtered range of SST and SSS and determine the expansion of the PGW mass in Oman Sea.

From the filter of OSTIA satellite data in the warm season of the studied years (2014-2019), it was observed that the PGW mass has shifted, so that PGW mass has gone further and moved to east about 0.12 degrees equal to 14 km in 2016 in compared with 2015 and about 0.08 degrees, equivalent to 9 km in 2017 in compared with 2016. The PGW can be transported in the Oman Sea, 300 to 350 km from the Strait of Hormuz. The width of PGW in the Oman Sea is about one degree (56-57˚E) in the warm season and 2.5 degrees (57-59.5˚E) in the cold season, by annual changes. (The widest expansion happened in 2015.).

This study represents that the difference of the highest daily SST of the warm and cold seasons (35.87˚C and 34.06˚C, respectively) were about 1.8˚C and the lowest daily SST difference of  the warm and cold seasons (18.27˚C and 13.11˚C, respectively) were about 5.16˚C. The average salinity in the warm season is about 34.08 psu to 36.49 psu with a range of changes of 2.4 psu. Whereas the average salinity is in the range of 34.51 psu to 36.50 psu with a range of changes of 2.01 psu in the cold season. Moreover, the surface water of the cold season (by filtered temperature of 28.5-30˚C) is located in the west of Oman Sea (58.5˚E to 59.5˚E). In the warm season, this water progress farther to the middle of Oman Sea (longitudes more than 59.5˚E), which indicates that the PGW mass penetrates more from its subsurface to the Oman Sea in the warm season.

The new insights into ocean-atmosphere-land synoptic studies, have led scientists to trace attractive atmospheric and oceanic phenomena. In this study, by using synoptic maps and some precipitation indices for Iran, we estimated the type and intensity of the extreme precipitation event in Dayyer Port synoptical station (27˚51ʹ34ʺN-51˚57ʹ52ʺ, ID: 40872) for 19March 2017. In order to identify oceanic sources of the water content for this precipitation event, air parcels were traced as lagrangian single particle trajectory by a hybrid model of HYSPLIT which is run backward interactively on the web site, during 9-days by the start of maximum rainfall, locatacted at Dayyer port station. Accordingly, we plotted pattern of the average moisture transfer paths on 800-550 hPa atmospheric levels. The field climate data (including wind speed and direction, relative humidity and precipitation) with 6-hour time steps and spatial resolution of 2.5˚×2.5˚(longitude and latitude), entered into the model from the reanalysis global data archive of the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR). Consequently, by assessment of the meteorological maps and data and by using a precipitation index of R10mm, we found that this precipitation event (19th March 2017) defined as a heavy precipitation day. Finally, the simulation outputs clearly showed that the water contents of this rainfall system (19th March 2017) originates from two source locations of the north area of Indian Ocean (Arabian Sea), and also the east part of Atlantic Ocean. In addition, the results illustrated that during the occurrence of this precipitation event, an extra-tropical cyclone was active on the studied area.

Due to the unique features of Persian Gulf, it is important to evaluate sea level changes temporally and spatially. In this study, the Sea Level Anomalies of Persian Gulf were processed using the average daily data of 25 years (1993-2017) with spatial resolution of 0.25 degrees along latitude and longitude in the Matlab software, to achieve the average monthly sea level anomaly patterns of Persian Gulf. The results show that the sea level anomaly is as an irregular oscillatory wave and its trend is incremental and equal to 2.9±0.1 mm/year (mean ± SD), which is 1.2 mm/year more than the global average rate. Monthly changes indicate that the sea-level anomalies are rising in October, November, and December and falling in February, March, April, and May, and other months can be considered as transitory months. The minimum sea-level anomalies occur in May (-0.05±0.19 cm) and their peaks occur at six months later in November (9.30±0.21 cm). The monthly spatial distributions are also different in the basin. By comparing the spatial patterns of different months, a relative symmetry was found between January and July, June, and December, which can be likened to a double-polar anomaly.

Waves play an important role in the geometry and composition of beaches. Iran has 700 km of coastline with the Caspian Sea, which is important understanding its waves. By reviewing sources, this study provides a comprehensive and analytical knowledge of the waves of Caspian Sea, so that the Caspian waves are wind-driven waves, and the prevailing waves of the southern Caspian are the western waves at first and then the northern waves (with a maximum height of 5.57 m). The maximum wave height is random due to the number of waves reaching the area and break of waves are more of spilling brakers. The exact pattern of the wind field (at the wave heights of 0.5-1.5 m), and the dimensions of the basin under the wind affect the formation of waves. Among the different simulation methods (JONSWAP, CEM, SPM, SMB, MIKE21 model (SW package), regression decision trees method and artificial neural networks) that can be seen in different studies, the last two methods with close answers have double accuracy in compare with others. However, the latter two methods lowerestimate the height of the wind waves slightly and overestimates the wave period slightly in compare with the measurement in South Caspian Sea.

Arvand River is the result of the combination of three rivers: Karun (from Iran), Tigris and Euphrates (from Iraq). In this research, the location of the plume of Arvand River has been identified by using temperature, salinity and density data of the ROPME (Regional Organization for the Protection of the Marine Environment) expedition during March, 1992, in the north of Persian Gulf region with Python programing along the vertical line. ETOPO2 was used in the Python environment to create topography of the region. Results clearly illustrate that the plume of Arand River in terms of temperature is near the coast of Saudi Arabia (150 km on bottom and 212 km on the surface), and, in terms of its salinity characteristic, the effects of Arand River are sharply limited to the coast of Kuwait (37 km), which is related to the more rapid mixing of temperatures compared with salinity.

The coastline, as a border where the water flow is relatively impermeable, can change the flow pattern and therefore, the study of its hydrodynamic role is undeniable. in coastal engineering studies and even wet ecosystems even it is simple. In this study, using three-dimensional simulations in the numerical model environment of MIKE 3, the Danish Hydrodynamic Institute, two types of three dimensional simulations have been proposed using Navier Stokes equations to investigate the role of the coastline in rectangular and curved basins. In both simulations, it is assumed that the characteristics of Qeshm's tidal channel are scientifically established. This study clearly shows that the uniform velocity pattern in a rectangular basin changes with the curvature of coastline on the curved basin. The tightness in the curvature of the basin causes an increase in speed (about 0.05 m/s) in accordance with the principle of mass conservation. The opening after the turn of the basin causes a decrease of 0.1 m/s (0.4 m/s in the rectangular basin to 0.3 m/s in a curved basin, equivalent to 25% speed). Another point to consider is the role of water level changes. There is not much difference in the speed pattern between Higher High Water (HHW) and Lower Low Water (LLW) in Neap tide, but in the case of Spring tide where the water level is higher, the difference is 0.1 m/s in the rectangular basin and 0.2 m/s in the curved shape basin.

Sea urchin as a bioerosion, is an effective factors on coral reef ecosystems which the observable biometry of urchin and its relationship with the jaw is important. Therefore, within this survey, sea urchin Echinometra mathaei were examined for summertime (July–September, 2014) between the intertidal areas of Dayyer Port (51˚53’49.39ʼ’E, 27˚50ʼ3.57’’N), Iran. A total of 91 individuals lively transferred to a lab. Total wet weight was weighted by a digital scale and the test height and diameters and the jaw length was measured by caliper (0.01 precision). The relationships between heights and diameters with weights were calculated according to indices and the relationships between the jaw lengths and test height and diameter were achieved. The results illustrated that the relationship between test height to its diameter (HDR index) is independent of test diameter (the slop near to zero) and therefore, there is a direct relationship between test height and diameter (a=0.47). Although the highest values of test height and spin length refer to males, but females achieved bigger values of test diameter, height and thickness (mean test height, diameter and thickness of females were 24.13±3.52 mm, 44.93±5.71 mm, 0.83±0.16 mm; and males: 21.22±6.82 mm, 37.67±12.27 mm, and 0.73±0.20 mm, respectively). The test diameter and weight of immature samples were less than 20 mm and 6.66 gr, respectively where can be as a primary criterion of Echinometra mathaei sexual maturity. Two indices HWR and DWR of both females and males had obvious differences with total samples, which also can be related to immature samples. Moreover, the jaw length was half of height (a=0.49, r=0.87) and a quarter of diameter (a=0.25, r=0.89). Results also illustrated well that larger samples had longer jaws that it could help identifying higher erosive samples.

In this current study، it is used an Estuary Lake and Coastal Ocean Model of Centre for water research of University of Western Australia، here after ELCOM، to employ a 3D hydrostatic non-uniform simulation of measured data of in late wintertime، 2005 in Oman sea area. The data was achieved by Global Temperature and Salinity Profile Programme، GTSPP. In order to that، simulation covers the whole basin of Persian Gulf، Oman Sea and north of Arabian Sea، to make the simulated profiles independent of Persian Gulf outflows and Indian Ocean Inflows. The simulation was run by temperature and salinity differences of Persian Gulf and Oman Sea، river discharges at the end of Persian Gulf، meteorological data of Qeshm Island for 4 months. Temperature results are in good agreements with measured data، while although salinity trend results are acceptable، the simulation is not capable to generate the low salinity water intrusion between 100 to 400 m.