scholarly journals A HYCOM modeling study of the Persian Gulf: 2. Formation and export of Persian Gulf Water

2010 ◽  
Vol 115 (C11) ◽  
Author(s):  
Fengchao Yao ◽  
William E. Johns
Ocean Science ◽  
2016 ◽  
Vol 12 (3) ◽  
pp. 687-701 ◽  
Author(s):  
Pierre L'Hégaret ◽  
Xavier Carton ◽  
Stephanie Louazel ◽  
Guillaume Boutin

Abstract. The Persian Gulf produces high-salinity water (Persian Gulf Water, PGW hereafter), which flows into the Sea of Oman via the Strait of Hormuz. Beyond the Strait of Hormuz, the PGW cascades down the continental slope and spreads in the Sea of Oman under the influence of the energetic mesoscale eddies. The PGW outflow has different thermohaline characteristics and pathways, depending on the season. In spring 2011, the Phys-Indien experiment was carried out in the Arabian Sea and in the Sea of Oman. The Phys-Indien 2011 measurements, as well as satellite observations, are used here to characterize the circulation induced by the eddy field and its impact on the PGW pathway and evolution. During the spring intermonsoon, an anticyclonic eddy is often observed at the mouth of the Sea of Oman. It creates a front between the eastern and western parts of the basin. This structure was observed in 2011 during the Phys-Indien experiment. Two energetic eddies were also present along the southern Omani coast in the Arabian Sea. At their peripheries, ribbons of freshwater and cold water were found due to the stirring created by the eddies. The PGW characteristics are strongly influenced by these eddies. In the western Sea of Oman, in 2011, the PGW was fragmented into filaments and submesoscale eddies. It also recirculated locally, thus creating salty layers with different densities. In the Arabian Sea, a highly saline submesoscale lens was recorded offshore. Its characteristics are analyzed here and possible origins are proposed. The recurrence of such lenses in the Arabian Sea is also briefly examined.


2008 ◽  
Vol 5 (2) ◽  
pp. 135-161 ◽  
Author(s):  
A. A. Bidokhti ◽  
M. Ezam

Abstract. Oceanographic data and a dynamic model are used to consider the structure of Persian Gulf outflow. This outflow influences the physical properties of Oman seawater which appear in the CTD profiles of the Oman Sea. The observations show that thickness of the outflow, which is banked against the Oman coasts due to the earth rotation, is about 200 m with tongues extending east and north that may be due to the internal waves. A simple dynamical model of the outflow based on potential vorticity conservation is used to find the horizontal extension of the outflow from the coast. Typical mass transport estimate by the outflow is about 0.4 Sv, which is larger than those reported by others. This may be due to the fact the model is inviscid but the outflow is influenced by the bottom friction. Variability of the outflow structure may reflect the changing ecosystem of the Persian Gulf. Any change of the outflow source, the Persian Gulf Water (PGW), say salinity increase due to excessive evaporation (climate factor) or desalination (anthropogenic factors) of the PGW may change the outflow structure and the product waters in the Oman Sea. Hence, one can test different scenarios of changing the outflow source, the Persian Gulf Water (PGW), say by salinity increase due to excessive evaporation or desalination (ecosystem factors) of the PGW to estimate changes in the outflow structure and the product waters in the Oman Sea. The results of the model show that these can increase the outflow width and mass transport substantially.


2019 ◽  
Author(s):  
Mathieu Morvan ◽  
Pierre L'Hégaret ◽  
Xavier Carton ◽  
Jonathan Gula ◽  
Clément Vic ◽  
...  

Abstract. The Persian Gulf Water and Red Sea Water are salty and dense waters recirculating at subsurface in the Gulf of Oman and the Gulf of Aden respectively, under the influence of mesoscale eddies which dominate the surface flow in both semi-enclosed basins. In situ measurements combined with altimetry indicate that the Persian Gulf Water is driven by mesoscale eddies in the form of filaments and submesoscale structures. In this paper, we study the formation and the life cycle of intense submesoscale vortices and their impact on the spread of Persian Gulf Water and Red Sea Water. We use a three-dimensional hydrostatic model with submesoscale-resolving resolution to study the evolution of submesoscale vortices. Our configuration is an idealized version of the Gulf of Oman and Aden: a zonal row of mesoscale vortices interacting with north and south topographic slopes. Intense submesoscale vortices are generated in the simulations along the continental slopes due to two different mechanisms. The first mechanism is due to frictional generation of vorticity in the bottom boundary layer, which detaches from the topography, forms an unstable vorticity filament, and undergoes horizontal shear instability that leads to the formation of submesoscale coherent vortices. The second mechanism is inviscid and implies arrested topographic Rossby waves breaking and forming submesoscale coherent vortices where a mesoscale anticyclone interacts with the topographic slope. Submesoscale vortices subsequently drift away, merge and form larger vortices. They can also pair with opposite signed vortices and travel across the domain. They can weaken or disappear via several mechanisms, in particular fusion into the larger eddies or erosion on the topography. Particle patches are advected and sheared by vortices and are entrained into filaments. Their size first grows as the square root of time, a signature of the merging processes, then it increases linearly with time, corresponding to their ballistic advection by submesoscale eddies. On the contrary, witout intense submesoscale eddies, particles are mainly advected by mesoscale eddies; this implies a weaker dispersion of particles than in the previous case. This shows the important role of submesoscale eddies in spreading Persian Gulf Water and Red Sea Water.


Ocean Science ◽  
2009 ◽  
Vol 5 (1) ◽  
pp. 1-12 ◽  
Author(s):  
A. A. Bidokhti ◽  
M. Ezam

Abstract. Oceanographic data and a dynamic model are used to consider the structure of Persian Gulf outflow. This outflow influences the physical properties of Oman seawater which appear in the CTD profiles of the Oman Sea. The observations show that thickness of the outflow, which is banked against the Oman coasts due to the earth rotation, is about 200 m with tongues extending east and north that may be due to the internal waves. A simple dynamical model of the outflow based on potential vorticity conservation is used to find the horizontal extension of the outflow from the coast. Typical mass transport estimate by the outflow is about 0.4 Sv, which is larger than those reported by others. This may be due to the fact the model is inviscid but the outflow is influenced by the bottom friction. Variability of the outflow structure may reflect the changing ecosystem of the Persian Gulf. Any change of the outflow source, the Persian Gulf Water (PGW), say salinity increase due to excessive evaporation (climate factor) or desalination (anthropogenic factors) of the PGW may change the outflow structure and the product waters in the Oman Sea. Hence, one can test different scenarios of changing the outflow source, the Persian Gulf Water (PGW), say by salinity increase due to excessive evaporation or desalination to estimate changes in the outflow structure and the product waters in the Oman Sea. The results of the model show that these can increase the outflow width and mass transport substantially.


Ocean Science ◽  
2015 ◽  
Vol 11 (5) ◽  
pp. 667-693 ◽  
Author(s):  
P. L'Hégaret ◽  
R. Duarte ◽  
X. Carton ◽  
C. Vic ◽  
D. Ciani ◽  
...  

Abstract. The Arabian Sea and Sea of Oman circulation and water masses, subject to monsoon forcing, reveal a strong seasonal variability and intense mesoscale features. We describe and analyze this variability and these features, using both meteorological data (from ECMWF reanalyses), in situ observations (from the ARGO float program and the GDEM – Generalized Digital Environmental mode – climatology), satellite altimetry (from AVISO) and a regional simulation with a primitive equation model (HYCOM – the Hybrid Coordinate Ocean Model). The model and observations display comparable variability, and the model is then used to analyze the three-dimensional structure of eddies and water masses with higher temporal and spatial resolutions than the available observations. The mesoscale features are highly seasonal, with the formation of coastal currents, destabilizing into eddies, or the radiation of Rossby waves from the Indian coast. The mesoscale eddies have a deep dynamical influence and strongly drive the water masses at depth. In particular, in the Sea of Oman, the Persian Gulf Water presents several offshore ejection sites and a complex recirculation, depending on the mesoscale eddies. The associated mechanisms range from coastal ejection via dipoles, alongshore pulses due to a cyclonic eddy, to the formation of lee eddies downstream of Ra's Al Hamra. This water mass is also captured inside the eddies via several mechanisms, keeping high thermohaline characteristics in the Arabian Sea. The variations of the outflow characteristics near the Strait of Hormuz are compared with variations downstream.


2010 ◽  
Vol 2 (4) ◽  
Author(s):  
Abdolreza Karbassi ◽  
Gholam Nabi Bidhendi ◽  
Mohsen Saeedi ◽  
Azadeh Rastegari

AbstractIn the present study, the removal of dissolved and colloidal Cd, Co, Cu, Ni and Zn in Arvand River water during estuarine mixing with the Persian Gulf water is investigated. The flocculation process was investigated for a series of mixtures with salinities ranging from 0.48 to 30.3^. The flocculation rates were indicative of the non-conservative behavior of studied metals during estuarine mixing. Rapid flocculation in the low salinity regimes was observed. The order of the final flocculation rate of metals in the river water was as follows: Co (91.2%)> Cd (86.9%)> Zn (83%)> Cu (75.2%)> Ni (74.3%). Salinity, pH, EC and dissolved oxygen do not govern the flocculation of metals during estuarine mixing. The results of the present investigation show that estuarine processes can be considered as an effective mechanism in self purification of colloidal metals that are anthropogenically introduced into the fresh water ecosystem.


2011 ◽  
Vol 2011 ◽  
pp. 1-15
Author(s):  
S. Hassanzadeh ◽  
A. Sedaghatkerdar ◽  
M. Soyuf Jahromi

This is a mesoscale modeling study of land/sea breeze in the vicinity of Bushehr, Iran which is on the coast of the Persian Gulf. Two days in September, 2002 are studied using the model presented in Estoque Model (1990) (hereafter referred to as EsM90). The EsM90 produces a realistic day-night wind field somewhat in agreement with observations provided by the Port and Shipping Organization of Iran. The study demonstrates that the model has a 3-hour delay predicting the time of the maximum of sea breeze, but accurately predicts when the end of the sea breeze occurs. Accurate estimates near mountains at the edge of the modeled region require a more complex simulation. The study shows that a reliable modeling of a complicated coastal environment like Bushehr not only depends on land/sea breezes but also on elevations and prevailing winds. This dependence is especially important when local thermal forcings are weak, for example, during late afternoon and at night.


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