The structure of the Persian Gulf outflow subjected to density variations
A. A. Bidokhti1 and M. Ezam2
1Institute of Geophysics, University of Tehran, P.O. Box 14155–6466, Tehran, Iran
2Faculty of Marine Science and Technology, Science and Research Campus, IAU, P.O. Box
14155–775, Tehran, Iran
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 200m 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.
Mesoscale Eddies of Arabian Sea: Physical-biological Interactions
S.A. Piontkovski1 , N.P. Nezlin2
1Sultan Qaboos University, CAMS, P.O. 34, Al-Khod 123, Sultanate of Oman
2Southern California Coastal Water Research Project, 3535 Harbor Blvd., Costa Mesa, CA 92626, USA
Satellite derived (SeaWIFS, TOPEX/Poseidon) products for chlorophyll-a concentration, sea surface heights, and calculated kinetic energy of eddies were employed, to analyze physical-biological coupling from 1997 to 2008. It was shown that, when cyclonic eddies dominated throughout the year, the chlorophyll-a concentration was positively related to the kinetic energy of eddies.
For the other years, when the total annual balance of negative to positive sea surface heights was dominated by anticyclonic eddies, the correlation was negative. The evaluated switch contributes a useful detail to the understanding of the mechanism mediating variability of the chlorophyll-a in regions with vigorous eddy fields.
Mesoscale eddies; Arabian Sea; Chlorophyll-a; Remote sensing
Seasonal Changes of Chlorophyll a and Environmental Characteristics in the Sea of Oman
Al-Hashmi, Khalid A. Claereboudt*, Michel R. Al-Azri, Adnan, R. Piontovski, Sergey. A.
Sultan Qaboos University, Department Marine Science and Fisheries College Agricultural and Marine Sciences, Box 34
Al-Khod 123 Sultanate of Oman
Monthly estimates of chlorophyll a, temperature, salinity, and nutrients were collected through sampling at two stations from January 2001 to January 2002, in and near Bandar Al-Khyran, the largest semi-enclosed bay on the southern coast of the Sea of Oman. Although the sampling location was at the limit of the tropical range, the seasonal changes of the coastal phytoplankton were more related to temperate dynamics, showing seasonal fluctuation of more than 10o C.
Sharp temperature drops observed in August and July were likely due to rises of the thermocline under the influence of coastal upwelling events or to deep water injections along the north coast of Oman generated by changes in the coastal wind patterns. Overall, small phytoplanktonic cells [0.7-5 μm] dominated the phytoplankton community of the mixed layer with an average of 69.7 % and 73.5 % of the extracted chlorophyll a at the station "Inside" and "Outside" the bay, respectively.
Keywords: Arabian Sea, picoplankton, chlorophyll a, coastal upwelling, phytoplankton blooms.