جستجوی مقالات مرتبط با کلیدواژه "ahvaz" در نشریات گروه "هواشناسی"

storm is one of the most important natural phenomena and a kind of natural disasters that influence many parts of the world. Dust storms cause many problems in different regions of Iran especially Khuzestan province every year. This province is affected by internal and external dust sources because there are some arid and semi-arid areas inside and outside of Khuzestan province especially in Iraq, Syria and Saudi Arabia countries. So a large number of studies have been done in order to analysis and simulation of dust storms. A severe dust storm has occurred in the west and south west of Iran on 7-10 Bahman 1395. The dust particles were drenched on the power transmission lines in Ahwaz city because of low precipitation on the 8th Bahman. So the electricity was cut off in the city. This event made many problems for residents of Ahwaz city. Synoptic analysis showed that, the existence of a cold front in the southeast of Iraq caused severe winds in the area on Bahman 8th. In Khuzestan province, ahead of the cold front, the south easterly winds triggered the activation of local dust hotspots located in the south of the province. The baroclinicity in the front area was quite apparent at the 850hPa level, and there was a deep height trough at the 500hPa. The output of HYSPLIT model in Khuzestan region near the surface showed the south-eastly wind flow. Also, the change in wind direction in the front area was clearly seen in the model output at 500m level. Present weather codes reported from Ahvaz synoptic station showed local and non-local dust storm and precipitation altogether. The visibility reduced under 100 meters in Ahvaz on 8 Bahman. WRF-Chem model with GOCART emission scheme was implemented for simulation of the dust event. The model outputs showed that the emission of dust particles from Iraq and south of Khuzestan was correctly simulated, and the they were in agreement with the satellite images; although the dust mass was not detected well, due to cloudiness in the region. The PM10 concentration of the model output and the measured values ​​at the air pollution monitoring stations showed that the model has a satisfactory performance in the estimation of the PM10 concentration. The model simulated the dust concentration trend correctly, however some errors in the output were seen. These errors were expected due to the complex topography of Khuzestan province. The model had a better performance in simulation of wind direction and rainfall. The model well simulated existence of the front and the sudden change of wind direction.

Climatic factors, especially rainfall, the most significant periods of time. Recognizing these changes, allowing optimum utilization of nature provides. The present research has been carried out with the purpose of time-based fluctuations of precipitation, the determination of droughts and wet periods, and the possibility of their prediction for Ahvaz. The wet and dry (droughts) periods and their intensity and successiveness have been estimated through the calculation of Z standard score and five-year moving mean. The possibility of their prediction has been accomplished by the use of time series models of Halt-Winters and auto regression. For doing so, we have applied the 45-year data precipitation records of Ahvaz synoptic station (1955 -2009). Results of our study indicate that the predicted values through Auto-regression have more proximity with the observed values.

Dust storm is an atmospheric phenomenon having adverse effects on the environment. These storms can have detrimental effects on economy and health of societies and create climate changes. Understanding the nature, origin, and effects of dust storms is important in determining their appropriate mitigation measures. In this review article, factors causing the occurrence of dust storms and their effects on environment, health, and economy as well as methods for locating and controlling them are discussed. This review article was conducted on various aspects of dust storms through internet and library search. Key words like Dust storm, environmental impacts, health, Air Quality، the Middle Eastern Dust event، were used to search for articles and publications in various databases such as Science Direct, Google Scholar, Springer, Magiran, and Iran Medex between 2014 and 2000. Totally, 200 articles were collected, 69 of which were chosen based on their relevance. Dust particles ascend as high as 6 kilometers and spread to 6000 kilometer across the surface, which reduces the horizontal vision to 103 to 104 meters. Atmospheric dust blocks the sun light and can also cause respiratory diseases, including meningitis and Rift Valley fever and asthma and viral diseases, and damage to the DNA skin and lung cells are. Increased to 10 micrograms per cubic meter in the concentration of particles smaller than 10 microns (PM10) at the time the dust phenomenon, the mortality rate of 0. 5- 1 percent increase.