جستجوی مقالات مرتبط با کلیدواژه « persian gulf » در نشریات گروه « مهندسی دریا »

This study concentrates on the 61tidal constituents of 17stations on the north of Oman Gulf(OG),Strait of Hormuz(SH)and Persian Gulf(PG).Five-years tidal data(2014-2018,30-minutes intervals) was achieved by Iran National Cartographic Center to calculate mean levels of stations.Then,t_tide library was used to calculate 61 tidal constituents by 95%of confidence in Matlab for 2018 data.Then, they sorted by the magnitude of the amplitude to express the most significant ones in each stations. Results shows that the mean levels of the northwest and northeast of PG are mirror images.Although the major diurnal and semidiurnal tidal constituents of 11stations areM2,K1,S2andO1,by changes in order of importance; in 6stations,N2 constituent is more important than O1. These exceptions go back to the stations of SH and northwest ofPG, which shows the importance of the SH bending and the shallowing of the northwest of PG. Moreover, the top ten components of all stations are not 10 unique components and they include 21 components.Due to the Form factor,F,all the studied stations are mainly mixed semidiurnal type. The predicted t-tide tides show small errors compare with the original ones. The results also showed that the range and components of harmonic astronomical tides are influenced by local geography. On the head of PG,the EmamKhomeini’s tides is sharp due to the shallow water, and the semidiurnal components(S2andN2)are much stronger than the diurnal components(O1andP1).The Pol Port’s tides is effected by narrowing of SH.Therefore, in some ports, non-tidal parameters such as geographical shape or shallow water are effective while considering astronomical components of moon and sun.

The open waters of the north Indian Ocean (NIO), which itself includes the Persian Gulf (PG), the Gulf of Oman (GO), and the Arabian Sea (AS), are subject to different meteorological forcing that can affect surface fluxes of these environments. In this study, latent heat flux (QLH), sensible heat flux (QSH), and surface wind stress (τ) between these regions are investigated. The reanalysis data from the data sets of the National Centers for Environmental Prediction (NCEP) and the European Center for Medium-Range Weather Forecasts (ECMWF) for these three regions for 14 years (2013-2000) are used. The results are compared with the measured data in the GO that show ECMWF reanalysis data are more consistent with the measured data in this period. We compare the average monthly, seasonal and annual values of QLH, QSH and τ of the PG, GO, and AS. The annual averages of QLH for the PG, the GO, and the AS are -128.63, -118.76, and -118.03 (Wm-2) and the annual averages of QSH are -1.28, -3.88, and -5.67 (Wm-2) respectively. The annual averages of τ are 0.074, 0.075, 0.036 (Pa) for these areas respectively. Also the annual average SST is 27, 26.56, and 27.14 (⁰C) respectively for these areas. Based on the results, different regimes of the PG wind with dust storms, and the limited and semi-closed space of the PG with its shallow depth, leads to different behaviors of QLH and QSH in PG area, in comparison with the other two environments (namely GO and AS).

The concentration of chlorophyll in marine environments indicates the quantity of photosynthetic plankton (phytoplankton),found in marine ecosystems.Phytoplankton populations are affected by weather conditions such as Sea Surface Temperature and Winds.They are also influenced by Aerosol Optical Depth (AOD),which can show the existence of dust.Moreover,there are seasonal variations and the correlation between these factors varies according to the depths.Despite the decrease in temperature and an increase in pressure on land areas during winter,which is accompanied by a decrease in strong winds, the formation of atmospheric fronts and strong winds caused the transfer of dust from susceptible springs in Saudi Arabia and the UAE and dust was transferred to it from the southern coast of the Persian Gulf. Investigating the long-term relationship between SST changes and the AOD with chlorophyll concentration on the Persian Gulf coasts as well as the Oman Sea,using daily MODIS products in the period of 2003 to 2020 demonstrates a strong correlation in coastal areas with the lowest depth.trend of SST and AOD on the both Seas is similar, along with the lowest values during the winter, while the seasonal trend show, the highest values of chlorophyll concentrations, in winter.Besides examining long-term chlorophyll concentration behavior over the Sea of Oman and the Persian Gulf, an emphasis was applied to the cold season of the year on February 17-22, 2018 for understanding the relationships between chlorophyll, AOD,and SST, showing the possibility of time delay in the correlation between sea surface temperature and optical depth of aerosols with chlorophyll concentration.

Red tide is a phenomenon that occurs by rapid growth or proliferation of toxic algae. The growth and spread of this phenomenon can threaten marine ecosystems, human health, aquaculture, water desalination plans, tourism and fisheries industries. Ocean currents are one of the affecting factors of the distribution of this phenomenon. In this study, the role of ocean current in chlorophyll-a distribution is investigated on the north coast of the Arabian Sea, the Sea of Oman and the Persian Gulf. The monthly MODIS satellite chlorophyll-a concentration data is used to study the red tide and the HYCOM model analysis result to study the current ocean pattern from 2002 to 2018 and in 2016 as an example. The currents in this area cause chlorophyll-a spreading and transfer of nutrients necessary for chlorophyll-a proliferation and red tides events. There are four main sources of chlorophyll expansion and proliferation in the region: the eastern shores of the Arabian Sea, the northern shores of the Arabian Sea and the Sea of Oman, the Strait of Hormuz, and the northwestern shores of the Persian Gulf. The northeastern currents in East Oman transport chlorophyll to the north of the Arabian Sea and the northwestern currents in the west of the Arabian Sea move chlorophyll from the coasts of India and Pakistan to the west and dispersed it to the west in the northern shores of the sea of Oman.

A strong low level jet (LLJ) in the northern region of the Persian Gulf (PG) observed on 5th Jun 2020 that sank the Behbahan cargo vessel. In this article, we have used the WRF-V3 model and reanalysis ERA5 data to study the vertical structure, diurnal variation and intensity of the LLJs. The aimed topography’s region, the pressure gradient and the land-sea breeze are the essential key factors in analyzing the diurnal variation of the LLJ over the PG that is known as the Shamal wind. The low terrain height in the northern of the PG and Zagros Mountains channelized the northwest winds and increased the pressure gradient that increased the wind speed. The decreasing friction over the PG during nighttime and the differences in temperature and specific heat capacity between water and land cause an increase in the LLJ intensity. The LLJ’s core 22-24 ms-1 was located over the study region in 925hPa on 4th and 5th June at 18 and 00 UTC respectively. Thereafter core’s wind speed decreased to 10-14 ms-1at 12UTC on 5th June. The mix-down of momentum from the LLJ level to the surface caused an increase in wind speed and wave height over the PG which sank the Behbahan cargo vessel at early morning of 5th June.  The LLJ at some regions like Kuwait formed at lower heights (under 950 hPa) and at the other points LLJ formed at levels upper than 950 hPa during nighttime of 4th Jun to afternoon of 5th Jun.

In this research, density, temperature and salinity fields were investigated in different seasons using observational data of ROPME Marine Cruise in the Persian Gulf (PG). Based on in-situ measurements, areas with density stratification were identified. Having analyzed Landsat and SAR satellite images, internal waves (IW) were detected in different regions of the Persian Gulf and more frequently in the eastern part of the PG related to seawater stratification. Based on analysis of satellite images, it is shown that the length of internal waves crest detected in the north-eastern part of Al-Zhahirah (Qatar) was more than 120 km; while it’s in range of 5 to 20 km in the south and east of Larak Island, 15 to 40 km in the north-east of Abu Musa Island, and 3 to 65 km in the south-east and south of Hondurabi Island. Moreover, IWs with shorter crest’s wide were recognized near Lavan, Siri, Farur, Halul, Khark Islands and Bandar Lengeh, as well. In addition, studying satellite images in the above mentioned areas for a longer time period from 2000 to 2017 showed that IWs mostly occur in the eastern part of the PG in summer and disappear in other seasons.

Hadish watercourse located in the in south of Iran, is a seasonal channel of water which crosses through Bandar Abbas to reach to the Persian Gulf. This watercourse is faced with numerous environmental problems in regard with the pollution entrance. Huge amount of the urban and industrial sewages of the city are discharged into this watercourse. In this investigation, considering the discharge of 1.36 m3/s into this watercourse, according to the literatures, the procedure of emission of pollution in the area was modeled. For this purpose Delft3D software has been employed. The model has been calibrated and evaluated considering water level data from Rajaee Port. It was found that, the pollution mainly remains inside the watercourse which is due to the ebb dominance nature of the channel. The results of this research show that the discharging the sewage into this channel endangers not only the western coast of Bandar Abbas, but the health of the citizens.

The nuclear disasters in Chernobyl and Fukushima have shown that such nuclear incidents are causing serious and undesirable long-term damage to the environment and the health of living beings, including humans. So that they should be taken very seriously. Considering the importance of the subject, in this paper, the simulation of the transmission and emission of cesium 137 nuclear abandoned from the contingency incident of Bushehr Power Plant in the Persian Gulf using the CROM (Código de cRiba para evaluaciÓn de iMpacto) code has been discussed. We assumed that the incident took place on July 1, 2018, and the most dangerous and an important nucleus of the abandoned is cesium 137. The simulation results show that the Cs-137 released from the incident is moved to the west and northwest of Persian Gulf and approach the head of the Persian Gulf after fifteen days. Then driven by the discharge of the Arvandrood River to the south coast and center of the Gulf moves forward and leads to the bottom. About two months later (late August) it will leave the Strait of Hormuz and will advance the Oman Sea and the Indian Ocean. Now, if this happens on January 1, after about 30 days, cesium 137 reaches the head of the Persian Gulf, and four months later (late March) will leave the Strait of Hormuz. The results of this study can be used under the same conditions in the nuclear emergency of Bushehr Power Plant.

The Khuran Channel, Southern Iran (26°45’N), is a topographically complex channel which is open at both ends. Owning to its particular geometry, this narrow channel is subjected to strong tidal currents.Across-channel distribution of the mean and tidal flows were obtained over a semidiurnal tidal cycle in the Khuran Channel where the highest tidal velocity in the third day of the secondary spring tide exceeded 140 cm/s. Velocity profiles were obtained using a 614.4 kHz Teledyne RDI Workhorse Broadband ADCP over 13 repetitions of a cross-channel transect. The 3.1 km long transect ran north/south across the channel.The M2frequencywas separated from the observed current using sinusoidal form functions and the least square regression analysis. Contrary to the previous study in this channel, the mean inflow observed in the deep parts of the channel and mean outflow occurs over the shallow slopes, with the maximum magnitudes (15-20cm/s) near the surface in the north side. The maximum lateral shear and convergence were found over slopes located between the middle and the north side of the channel.

Marine areas are affected by different atmospheric phenomena such as wind and storm. In this research the effect of a large scale atmospheric phenomenon, known as Winter Shamal Wind, is investigated on the regime of currents and waves in the northwest part of the Persian Gulf. This wind normally occurs for the period of three to seven days, during December to early March. MIKE21 Coupled Model FM was applied to study the pattern of current and waves for this period. To provide the hydrodynamic data for the model and validate the simulated results, the wind data of ECMWF and mast meteorology of coastal synoptic station of Bushehr and wave data of buoy located offshore of Bushehr was used. The results indicated only a slight increase in current speed with no significant change in current direction during Winter Shamal Wind, showing a stable current pattern in northwest of the Persian Gulf. The significant wave height and wave propagation speed for the period of Winter Shamal Wind in comparison with the days prior to the wind show significant changes. The maximum wave speed in the area under investigation reaches up to 1 m/s and the significant wave height is almost 1 meter higher than that of normal situation.