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Showing 7 results for Storm

Professor Ghasem Azizi, , Leyla Sharifi,
Volume 17, Issue 47 (12-2017)
Abstract

Thunderstorms are major climatic events due to the significant effects and catastrophic consequences on humans and the natural environment. The researches have shown that the elevation and latitude factors are two variables that can affect the occurrence of this phenomenon. Therefore, the main aim of this study is to investigate the spatial analysis of the effects of lightning and its effects on the components such as elevation and geographic extent in Iran. Apart from this fact, firstly, the monthly data of thunderstorms occurrence in 118 synoptic stations of Iran, from 1991 to 2010 on a basis from the country's meteorological organization were obtained and GIS software was produced by the annual and seasonal maps of Iran. Then, for the spatial analysis of this climatic phenomenon, the method of landing statistics of the Kriging (Universal) method was to examine its seasonal and annual status. In order to better understand the effect of Thunder hurricanes from altitude and latitude using Curve Expert software, seasonal and annual charts, along with the correlation of each production, were analyzed. The results show that the highest annual thunderstorms occur in the northwest of Iran, and the least amount is consistent with the central and eastern parts of the country. In addition, according to seasonal analysis, although the station has the highest rate at 800 to 1,300 meters, the maximum occurrence of this phenomenon varies from 0 to 2200 meters in different seasons of the stations. The overall result shows that the factor of height is slightly correlated with the occurrence of the Thunder storm phenomenon and the highest correlation is due to the latitude factor.
Mrs Faranak Bahrami, Mr Abbas Ranjbar.s.a, Mr Ebrahim Fattahi,
Volume 18, Issue 50 (3-2018)
Abstract

Probable maximum precipitation (PMP), is the highest rainfall, which occurs at a given time in a basin. Hydrologist calculates the probable maximum flood for the design of overflow dams, by using the PMP, with two methods: statistical and synoptic. The purpose of this study is calculating PMP in the Ghomrood basin by using the synoptic method. For this purpose rain, meteorological data of the Iran’s Meteorological Organization were used. Also, the data on the 850 and 500 hPa levels were analyzed by the National Center for Environmental Prediction and the National Center for Atmospheric Research (NCEP-NCAR). In the following, the required synoptic maps produced and were studied. Iso rain maps were drawn, and depth-area-duration curves were determined. Eventually, PMP was estimated at 24, 48 and 72 hours. So that 24 hours PMP, by calculating 50 and 100 years return period of dew point estimated 51/75 and 54 mm respectively. Also for 48 hours PMP 128/25 and 132/05 mm, and for 72 hours PMP 97/9 and 101/75 estimated.

Yousef Ghavidel Rahimi, Manouchehr Farajzadeh, Esmaeel Lashani Zand,
Volume 18, Issue 51 (6-2018)
Abstract

In this study, the changes in the Khorramabad storm in the period of 1952 to 2015 have been investigated. For this purpose, data from meteorological codes 06 and 07 were received from the Meteorological Organization of the country, and after identifying the days of winding with dust storms and calculating their monthly frequency, monthly, seasonal and annual time series were analyzed. In this study, descriptive statistics, cluster analysis, linear and polynomial trend analysis, and nonparametric Mann-Kendal test were used to study the frequency variation of dust storms in Khorramabad station. The results of the research showed that the monthly frequency of dust storms in Khorramabad station in the middle of May, July and June is May and July, respectively, and from May to July (May to July), the frequency of storms in the dust and dust Khoramabad station is added that this issue is not related to the district heating and dry season. In the seasonal season other than the autumn, which is not frequent with frequent dust storms, in the rest of the seasons, especially in spring and summer, the seasonal concentration of dust storms in Khoramabad has been intensified. The analysis of the trend of time variation in the occurrence of dust storms in Khorramabad station showed that in most of the months of the year and in the three seasons of spring, summer and autumn, as well as in the annual period, there was a significant change in the frequency of dust storms in Khorramabad station. It is increasing with a relatively steep slope, indicating that in the future, the frequency of dust storms in Khorramabad station will be increased.

Mr Soleiman Pirouzzadeh, Mahmood Khosravi, Samad Fotohi,
Volume 19, Issue 52 (3-2019)
Abstract

 Studies show that 14 provinces are impacted by wind erosion and the movement of sand dunes. The sand originated from the shores of Oman Sea is the most important environmental hazards that threaten the already large number of rural settlements. Sands of marine origin are available on the beach and away from the sea of dunes in addition of marine origin, Predictive models for planning sustainable use of land use and land cover in a country like Iran that land use is changing rapidly, there is an urgent need; To detect and predict changes in land cover changes overview to better manage natural resources and protect marginal lands beaches and is very effective long-term policy measures. The aim of this paper is  modeling and prediction of changes in  land-use in 2035 by using  CA Markov model and Landsat satellite images in the West of Zarabad,( The coasts of Makran). Then to determine the changes in the movement of sand dunes in the study area ranged from twenty-three years (1991-2014), satellite imageries from Landsat 7 and 8(ETM+ sensor) with 15 and 30 meters spatial resolution , was used. The 1991, 2001and 2014 month August images were used, this images from website of the US Geological Survey (USGS) have been prepared. Finally, these images by using Geographic Information System (GIS), ENVI and IDRISI softwares were analyzed. The results  showed that the changes in the region the largest increase in the interest of sand dunes in the year 1991 (25.561) km², in 2001 (10 . 568) km², and in 2014 (45.578), and the increase of (17.198) km², has experienced. The results also estimated that in future (2035) sand dunes area increase to 592.45 km².This  increase in area of sand dunes occur in the absence of proper and efficient management is done in order to stabilize the sand. This increase resulted from changed moorland 162 km²of land area (27%) and 12 kilometers of vegetation (2%) and 23 km² of fluvial (3.4%). These changes makes heavily exposed about 6 villages (Karti,Gnjk, Sohroki, Pyvshk, Vanak and Kalirak) to the movement of running sands.

Asal Falak, Reza Boran, Farideh Asadian,
Volume 21, Issue 62 (9-2021)
Abstract

This study aimed to investigate the temporal-spatial and synoptic features of thunderstorms in southwest of Iran (Khuzestan, Chaharmahal & Bakhtiari and Kohkiluyeh & Boyerahmad Provinces) It was compiled using volatility indices during the period 1985-2015. Results of Frequency Analysis of Thunderstorms at Dezful Station with 479 cases the highest frequency and Ramhormes with 252 days had the lowest frequency. In terms of seasonal distribution, spring was the most abundant with 39%. On a monthly basis, April had the lowest frequency with 21% and August with only 2 cases. In terms of thunderstorms the highest frequency of thunderstorms with no thunder was 21 percent. Synoptic analysis: Most of the time there is a nave (at level 500) or low pressure in the west of the region, east of the Mediterranean Sea with its tabs clockwise. From the Red Sea and the Persian Gulf, they entered the south, southwest, and west of Iran On the other hand, the high-pressure system on the Gulf of Aden in the east of the region is round in the clock It has injected moisture, especially at a level of 850 millibars. Interaction between the two systems over the course of the day, It has injected moisture from three sources of the Mediterranean Sea, the Red Sea and then the Persian Gulf into the rising systems of the region. The low-pressure counterclockwise movement of the eastern Mediterranean, Along with the high-altitude clock movement over the Gulf of Aden, it has injected moisture at levels of 850 to 700 degrees.

Dr Behrouz Sobhani, Dr Mehdi Aalijahan,
Volume 24, Issue 73 (6-2024)
Abstract


Today, fine dust and dust storms have become one of the important issues and problems of Iran and other regions of the world. This study is conducted to identify synoptic patterns of the dust storms in Ardabil Province (Iran) and monitor the origin and pathway of its places. The studied period is 34 years (1979-2013). The data used in this work are from synoptic stations of Ardabil province and the NASA’s upper atmosphere database. To achieve the goals of the study, the Environment to Circulation, Hierarchical Clustering Methods, and HYSPLIT model were used. According to the results, three patterns of geopotential height at 500 hPa levels were identified. Pattern No. 1 and 2 are almost similar to each other and represent the occurrence of a deep trough that formed from Central Europe and extended to the middle of the Red Sea. Based on these patterns, the study area is located in the East of this trough. The third pattern represents the occurrence of cut-of-low pressure blocking over the Black Sea and adjacent areas and placement of Ardabil province in the East trough of the formed blocking. The origin of dust in patterns 1 and 2 is the Eastern regions of Iraq and West of Iran while in pattern 3 is at 500 hPa level of the central areas of Iraq and at pressure levels of 850 and 1000 hPa of the central regions of Syria.
Keywords: Dust storm, Pattern extraction, synoptic analyses, HYSPLIT model, Ardabil province


Dr Sara Karami, Dr Nasim Hossein Hamzeh, Dr Abbas Ranjbar,
Volume 24, Issue 74 (9-2024)
Abstract

Today, dust storms affect the lives of many people around the world and cause a lot of financial and human losses. Every year, Iran is affected by dust storms caused by internal sources and external dust sources located in neighboring countries. Semnan province has several dust-producing sources due to its geographical location, that affect not only this province, but also the neighboring provinces. The purpose of this study is to investigate the dust phenomenon of Semnan province and its monthly changes in the 15-year period, between 2003 and 2017. For this purpose, meteorological stations data of the province and the aerosol optical depth of satellite product have been investigated. Also, GOCART model has been used to estimate the amount of dust emissions from this region and to determine the vertical dust flux in Semnan province. The study of average dust flux showed that the highest values ​​of dust flux was in the southeast of Shahroud and then in the south of Shahroud, Damghan and Sorkheh. A monthly investigation showed that in all months, the average AOD in the southern half of Semnan province was higher than in the northern half. The highest levels of AOD were in May, April and June, and the highest amounts of dust flux were observed in March, June and July. Also, the prevailing wind direction was northeast and northeast, and this factor causes dust particles rising from this region and dust loading in the south of Semnan province and areas of Isfahan, Yazd and South Khorasan provinces.

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