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Showing 13 results for Iran.

Peyman Mahmoudi, Taghi Tavosi, Daneshmand Hojjat, Abdolmajid Shabab Moghadam,
Volume 1, Issue 2 (7-2014)

Hot, humid weather causes to the sultry feel. Sultry condition is usually accompanied with loss of physical ability and human respiratory and it has an adverse effect on peoples who have circulatory or other heart problems and this feeling is more than others. Sultry feel is a feeling like any other sensitive reflections of mental state. And this state apparently can’t be measured by special instruments. With this description, there are a lot of efforts has been done to identify this phenomenon by meteorologists and climatologists. And a series of psychological climate tests show that we can examine the creation and incidence of this sense based on empirical studies as a scientific and objective attitude. Therefore, this study aims to classify the sultry days in the southern half of Iran based on sultry continuous hours. And the obtained results are presented as a form of zoning maps.

     The studied zone in this research is selected stations in the southern half of the country located in the province of Sistan & Baluchestan, Kerman, Hormozgan, Fars, Bushehr and Khuzestan. This area is located between two latitude 25 and 35 north and length of 47 to 63 east degrees. To achieve this goal, hourly partial pressure of water vapor of 13 selected stations were obtained for a period of 15 years (1995-2009) from Meteorological agency. After obtaining data and creating the database, to separate sultry conditions from non-sultry conditions, threshold of partial pressure of water vapor of Scharlou which was equivalent to 8.18 Hpa were used.

    Based on these data, the hours and days that the partial pressure of water vapor was equal or greater than 8.18 hpa will have sultry conditions and otherwise, they have non-sultry conditions. Then, based on this threshold, sultry days were divided into eight categories. The basis of this classification is that if in a particular day among eight branches of observation, one station, only in one observation record a pressure equal to or greater than 8.18 hpa was observed, it will be placed in first class and if only two observed records a value equal or greater than defined value, it will be placed in second catagory and finally, if all eight observations amounts equal to or greater than 8.18 had been recorded, it will be placed in eight class. After placing the sultry days in one of eight branches of classes, long-term averages of monthly, quarterly, quarterly and annual were calculated and mapped.

    Based on defined thresholds, sultry days were separated from non-sultry days, then sultry days were extracted and it was placed in first to eighth classes. The results of this classification showed that on monthly scale, January has the fewest sultry days in twelve months of the year. In this month, only two stations of Chabahar and Bandar Abbas had the sultry days of eighth classes. It means that 24 hours, they were in sultry conditions. Other stations that have a sultry day in this month, often their sultry days are from first to fourth classes and it means that they had maximum 3 to 12 hours of sultry conditions during the day. Most sultry days can be seen in two June and July months. So, in these two months, all studied stations have at least one sultry day,Specially  in three stations of Chabahar, Bandar Abbas and Bushehr. And all 61 days, they have sultry conditions. In terms of classification of sultry days, all 61 days of Chabarhar station are part of sultry days of eighth class. In two stations of Bandar Abbas and Bushehr, except few days that are from sixth and seventh classes, other days are from eightth class, other stations experienced one of the eightth classes of sultry days with different ratios. , and at the seasonal scale, winter has the lowest days of sultry and summer has the most days of sultry days. In term of classification of sultry days in seasonal scale, there are conditions as monthly scale. The interesting point in summer season is that sultry days on two stations of Zabul (35 days) and Iranshahr (51 days) are considered due to their Geographical locations. In Zabul station, the reason of these sultry days can be due to the neighborhood of this station with Hamoon Lake. But it should be mentioned about Iranshahr stationthat the reason of its sultry condition is entrance of monsoon low pressure and moisture transfer by the system on the south-east of Iran an especially Iranshahr. On an annual basis, it was also observed that always in south east of Iran (Especially Chabahar station), the number of sultry days is much more than south west of Iran, also occurring sultry days with eighth, seventh and sixth classes in this zone is so different from south-west of Iran. The reason of these differences in number of sultry days and sultry classes  related to the latitude of south east of Iran which is lower that south west and in other words, we can say that climate of south East of Iran is more similar to tropical climate than subtropical climate. 

Manuchehr Farajzadeh, Yosef Ghavidel Rahimi, Mehdi Ardeshirikalhor,
Volume 1, Issue 2 (7-2014)

Ultra violet radiation has some useful effects and some harmful effects on human health an d create many diseases. Nowadays not only declined but the usefulness of the therapeutic effects of the Sun in the treatment of diseases such as rickets, psoriasis and eczema have been proved. But prolonged exposure to radiation of the Sun is not always beneficial and may cause acute and chronic effects on the health of the skin, eyes and immune system. Ultraviolet radiation of the Sun is one of the most destructive waves for life on Earth. So Ultraviolet radiation index and predict its rate (1 to +11) as well as the analysis of this indicator will help people to protect themselves against the Sun

    Ozone station , global ozone measurement stations and only stratosphere in Isfahan, Iran, which is in the South and in the Northern geographical position latitude 32' 31 and 70 ' 51 is located over the East. The altitude of this station from sea is 1550 m. Also atmospheric parameters in this station which are measured daily include temperature, pressure, humidity, wind speed and direction and in the upper levels of the atmosphere at 12 GMT with the help of Joe's high temp radio instrument.

    The first step to do this research was gathering of climatic data and the statistical and quantitative analysis in order to study on the subject. Ultraviolet radiation data on the same basis of assessment, ozone station during the period January 2001-December 2010 has been collected. The second batch of data information gathered from meteorological station of Isfahan climatic elements from 2001 to 2010. This data is based on monthly averages for analysis of solar UV radiations from meteorological solidarity with the country.

Adjust the time series at the first step in the study and analysis of the data was done in order to equal intervals in these regular categories and methods of statistical analysis was carried out on them and the overall process of UV changes in the form of daily, monthly, quarterly and annually. Also part of the analysis that was carried out on the data, check how the sequence or they had over time; this way specify whether data periodically changes or trends have been or not. Once the data is based on the time of occurrence, sort and arrange the time series on them.

Annually analysis of UV index showed the general variation is a common feature of studied years but in the spring season have high variation in compared with other season. The main reason of this variation may be related to sunlight angle that can be showed atmosphere effect on received radiation. Descriptive statistic result indicated that the highest mean of UV index is 6.52 and minimum were 4.8 that have very high variations and may be it has different harmful effects. Also seasonal analysis showed highest UV index created in hot summer related to highest temperature in this season. The computational modeling of UV index against years in different season indicates there do not exist a linear relation between two factors. The correlation analysis of UV index and some climatic factors showed there are a significant relation between temperature  with 0.8570 coefficient that  can be said in relation to increase of temperature, UV rate increased and vice versa and with cloud cover correlation coefficient is  -0.393 that have significant negative relation.

    Results showed that the peak time period are output in the first half and the second half of the year, landing in the specified time series. As well as through a linear fit to all charts, increase or decrease of the radiation, changes the trend in recent years, showed that based on the ultraviolet radiation changes the average increase in the spring and summer and fall and winter shows a decline. Also according to the ultraviolet radiation in daily statistics review ozone assessment station in the studied period (2001-2011) maximum amounts of ultraviolet radiation index, (11.5) observed in the middle of the summer and the minimum amounts of radiation index (0.5) observed in mid-winter.

Mahdi Zare, Farnaz Kamran Zad,
Volume 1, Issue 4 (1-2015)

The Iranian plateau formed by the active tectonics of the Alpine-Himalayan belt, is situated between the Eurasian and Arabian plates. The plateau is considered as one of the most seismically active regions in the world and is faced with different earthquakes each year. Active tectonic conditions, different faults and seismic sources and a large population in earthquake-prone areas makes it necessary to perform more considerations and scientific studies in order to analyze the seismic hazards and risks.

In this paper, different aspects and effects of the Iranian seismicity has been determined. In order to review the status of seismicity and distribution of earthquakes in Iran, we need first to consider the tectonic setting, structural environment and the active faults of the country. To date, there have been some different studies to divide the the seismotectonic setting of Iran into different seismic zones which are explained in this paper briefly. Moreover, the seismicity and most destructive past earthquakes in the Iranian plateau and distribution of earthquakes are shown.

    One of the most important tools in studying earthquakes is to perform continuous recording and monitoring of the seismic event and ground motions which is implemented using seismic and strong motion networks. The systematic networks have been set up within the country and are working and responsible for data collection and monitoring of seismic events permanently. These networks including the Iranian Seismological Center (IRSC), broadband seismic network of the International Institute of Earthquake Engineering and Seismology (IIEES) and strong motion network of the Road and Housing and Urban Development Research Center (BHRC) are also introduced in the current study.

Given the high seismicity rate in Iran and rapid development and growing of the populated cities and buildings on seismic hazard prone areas, attention to seismic hazard and risk assessments has been become as a particular issue that should be addressed carefully. Therefore, seismic hazard analysis and estimation for the constructions of human structures has become an enforcement for which several seismic regulations and codes have been defined. In this regard, deterministic and probabilistic seismic hazard methods have been developed as the two most important techniques. The deterministic method is a conservative approach that is mostly used to determine the highest level of strong ground motion (acceleration) for a special site (such as dams and power plants). On the other hand, the probabilistic method provides probabilities of different strong ground motion levels considering different uncertainties and the useful life of a structure.

    In addition, considering the level of seismic hazard in a region and its population can lead to risk assessment, vulnerability and resiliency of the human societies. Thus, parallel to seismic hazard and risk analysis, it is so important to conduct crisis management, reduce efforts and a continuing assessment of the situation in the country. In the present study, problems and challenges facing the crisis management, as well as urban distressed areas are mentioned.

    Regarding the existence of constant threat of natural disasters, especially high risk of earthquakes, there is a serious need to conduct more scientific researches in various fields, including detailed research on various aspects of seismology in Iran, retrofitting of constructions, crisis management and disaster risk reduction. To achieve this purpose, we need a scientific network in Iran. There sould be several experts and organizations as the members of this network who are able to understand and control the earthquake effects on the society. Necessity of such a scientific network is due to that it is impossible to take efforts in order to reduce the earthquake risks without a holistic perspective and earthquake data completion.

In this regard, we need significant infrastructures in terms of human resources and technical cooperation to motivate a set of organizations, universities and research institutes. The responsible organizations such as geological survey of Iran, National Cartographic Center of Iran, meteorological organization, Institute of Geophysics of the University of Tehran, International Institute of Earthquake Engineering and Seismology, Road and Housing and Urban Development Research Center, National Disaster Management Organization, Red Crescent Society of the Islamic Republic of Iran, as well as universities and NGOs must work together to make it possible to review and integrate the existence potentials and to share the information and data of the earthquakes in Iran and define various response scenarios faceing natural disasters, especially earthquakes.

Amir Hossien Halabian, Fereshteh Hossienalipour Jazi,
Volume 2, Issue 4 (1-2016)

We can identify the flood not only considering circulation pattern in occurring day but also by studying circulation pattern a few days before fresh event. This subject has mutual approach. In one hand, it indicates  that circulation patterns which were before flood event have important role in determining the conditions and moisture content of studied area and playing the fundamental role in few coefficient of region because it determines the previous moisture. On the other hand, it indicates that we should tracking the rain-genesis synoptic systems from source to end place of their activity for studying floods and their meteorology factors which have created them. By this way, we can acquire more comprehensive recognition about the relationship between circulation pattern and floods. In the other words, the identification of synoptic patterns that have created the flood reveals not only the mechanism of their emergence but also is useful for prognosis and encountering with them. The extensive researches have been accomplished about Inundation in the world and Iran, but Iran haven’t much antiquity about synoptic researches. For foreign researches, we can name researchers such as Hireschboeck (1987), Kutiel et al(1996), Komusce and et al (1998), Krichak  and et al (2000), Rohli and et al (2001), Kahana (2002), Teruyuki Kato(2004), Ziv and et al (2005), Carlalima and et al (2009). The numerous researchers have studied the Inundation climatology in internal of country such as Bagheri (1373), Ghayour (1373), Kaviani and Hojatizadeh (1380), Moradi (1380), moradi (1383), Mofidy (1383), Masoodian (1384), Masoodian (1384), Hejazizadeh et al(1386), Parandeh Khozani and Lashkari (1389). In this research, we considered the heavy precipitation of Azar 1391 in southwestern of Iran that resulted in flood phenomenon in the cause and effect manner so that can do necessary prevention actions before occurring the flood for preventing the probable damages and optimal use of precipitations by forecasting the patterns that have created the flood.

In this synoptic study, we need to two database: one group is variables and atmospheric data consisting of geopotential height of 500 hpa level (in meter geopotential), zonal wind and meridional wind (in m/s) and special humidity (in gr/kg) during this times 00:00, 06:00, 12:00 and 18:00 Greenwich in 0-80° northern and 0-120° eastern with local resolution of 2.5*2.5 Arc that have been borrowed from database of (NCEP/NCAR) dependent to National Atmosphere and Oceanography Institute of USA, and other group is daily precipitation data of region rain gauge stations during 4-8th Azar of 1391 (24th November – 28th November 2012). In continuation. By applying the environment- circulation approach, we took action to drawing circulation pattern maps of 500 hpa level, thickness of atmosphere patterns of 500-1000 hpa and moisture flux convergence function from 4-8th Azar of 1391 (that for calendar, conform with 48 hours before beginning the showery precipitation until ending the storm activity) by using data which obtained from database of NCEP/NCAR and the synoptic conditions of above flood have been studied and interpreted in the region.

Flood is one of the most destructive natural hazards that have imposed and impose many damages to people during the history. Hence, the final aim of this research is to explain the key interactions between atmosphere and surface environment and in other words exploration of the relationship between circulation patterns leading to the flood generating precipitation in the southwestern of Iran for forecasting the time and intensity of showers occurrence that lead to flood. For this purpose, by applying environmental-circulation approach, the circulation patterns identified and studied which resulted in flood generating precipitation. The result of this research indicated that torrential precipitations in the region have formed the deep trough in days 4-8 of Azar on the east of Mediterranean and the studied region placed in the east half of this trough that is the location of atmosphere instability. At same time, thickness patterns, indicate the flux of cold air from northern Europe to lower latitudes and spreading the warm air of north of Africa to latitude 50° northern. As a result we expected the frontal discontinuity in the encountering place of these two air mass. Analysis of the moisture flux convergence patterns also indicated that torrential precipitations were the result of moisture flux from Mediterranean and Persian Gulf; and Red Sea and Arab Sea taken into account as reinforced sources.

S. Reza Alvankar, Farzane Nazari, Ebrahim Fattahi ,
Volume 3, Issue 2 (5-2016)

Due to the growth of industries and factories, deforestation and other environmental degradation as well as greenhouse gases have been increasing on the Earth's surface in recent decades. This increase disturbs the climate of the Earth and is called climate change. An Increase in greenhouse gases in the future could exacerbate the climate change phenomenon and have several negative consequences on different systems, including water resources, agriculture, environment, health and industry. On the other hand to evaluate the destructive effects of climate change on different systems, it is necessary to initially study the area affected by climate change phenomena. One of the most important effects of climate change on water resource is Drought.  On the other hand, one of the most serious consequences of climate change is how it will affect droughts and water resources.

Drought along with warmer temperature and less precipitation will threaten the water supplies for the crop irrigation, which will directly reduce the production of crops.The climate of the 21st century will very likely be quite different from the climate we observed in the past. The changes will continue to be large in the future period with increasing carbon dioxide emissions. Analyzing and quantifying the signal of climate change will be much in demand considering the above sectors, which are highly relating to the sustainability and human living.

In the past several decades, global climate models have been used to estimate future projections of precipitation [Intergovernmental Panel on Climate Change (IPCC), 2007], and have led to future estimation of drought, to quantify the impact of climate change and comparing the duration  and intensity of droughts under future climate conditions with current climate by using Atmospheric-Ocean General Circulation Models AOGCMs to predict future Precipitation. Global circulation models namely, coupled Atmosphere-Ocean Global Climate Models (AOGCMs) are current state of the art in climate change research. in This study aims at investigating the impact of climate change on droughts conditions in Iran using the Standard Precipitation Index (SPI).

The precipitation time series have been used for the estimation of Standardized Precipitation Index

(SPI) for three timescales, 3, 12 and 24 months, for the region. The outputs of HadCM3-A2 and A1B were applied for the assessment of climate change impact on droughts. One of the major problems in using the output of AOGCMs , is their low degree of resolution compared to the study area so to make them appropriate for use, downscaling methods are required. In this study we have used lars WG for downscaling monthly average of rainfall of AOGCM-HadCM3, and The HadCM3 outputs were downscaled statistically to the study area for a future period 2011-2040.then, was evaluated by the coefficient of determination (R2) between observed and downscaled data.  A method has been used for the estimation of annual cumulative drought severity-time scale-frequency curves. According to the rainfall results, in the 2011- 2040 period rainfall would decrease  to compared to baseline period in the study area.

The SPI time series were estimated (2011-2040) and compared with the respective time series of the historical period 1961-1990. Results revealed that there are decreases in the frequency of severe and mild droughts for the three examined SPI time series while there are increases in the duration of moderate droughts. This implies that droughts will be a concern in the future during the growing season (for the dominant crop) which should be considered in water resources management. specially in the west station of Iran.

Also, these frequency ratios were mapped by GIS on study area. Results showed that generally in the future periods, frequency of droughts ratio of three months drought time- scale will be increase in the North, North West and some parts of the south Alborz mountains and, The Ratio of long ( 24 months) drought for scenario A2 compare to the current climate shows increasing drought in the parts of the North khorasn, sistan and baluchestan and kerman provinces and parts of South West of Iran. scenario A1B shows increasing drought in the parts of the East of Mazandaran , Tehran , Horozgan and parts of Fars and Yazd  provinces.

Finally ,further  more analysis of drought, AWCDS-Timescale-Return Periods computed. These curves integrate the drought severity and frequency for various types of drought. The AWCDS time series were estimated

for basic period and 2011-2040 under scenarios A2 and A1B. The comparison indicated the three types of drought intensity increases for the three examined SPI time series in the South East of Iran.

Ali Bayat, Mohammad Saligheh, Mehri Akbari,
Volume 4, Issue 2 (7-2017)

Cyclones as the most important factor in the turbulence of mid-latitude regions are low pressure centers that have one or more closed Isobaric curves. Mid-latitude cyclones are responsible for transfer of the heat and moisture between the tropics and the polar regions. Mediterranean cyclones have the most important role in Iran's rainfalls and get from different tracks to the country and affect Northwest, West and South West of Iran in the cold period of the year. Cyclones are the prevailing weather phenomenon in Mid-latitude region and studying the characteristics and effects of these phenomena has always been of interest to climatologists and meteorologists. Iran which is located in mid-latitude region, actually is located in the path of one of the world's largest cyclone formation and the Mediterranean Sea has a main impact on the rainfall occurrence in Iran. Regarding the importance of cyclones in rainfall occurrence in Iran, especially in cold season, studying this atmospheric event seems very necessary.
The aim of this study, is to identify, tracking and analysis of the winter season (December, January and February or DJF) rain producing cyclones using special database and algorithm during three recently decades (1979-2009). 
In this study, in order to specify, tracking and statistical analysis of the DJF rain producing cyclones, relative Vorticity of 700 hPa were received from ECMWF data center  with AWT IMAGE spatial resolution  and temporal resolutions of 6-hourly for a 30 years period (1979-2009). The study domain includes Mediterranean and Middle East, from AWT IMAGE E to AWT IMAGE E and AWT IMAGE N to AWT IMAGE N.
Cyclone identification will follow the approach presented in Blender et al. (1997) and Flaounas et al. (2014), including two important points and conditions: 1- A cyclone is considered to be a relative Vorticity extrema, thus the aim will be to look for the maximum value of relative Vorticity at the 700 hPa level in a box of AWT IMAGE grid points. 2. For the intensity of the cyclone, the threshold of relative Vorticity, is considered equal or greater than AWT IMAGE. Then by 6-hour tracking the maximum amount  points of Vorticity  and connecting them to each other, identification and routing of cyclone is implemented. The track AWT IMAGE can be written as AWT IMAGE, where AWT IMAGE describes the cyclone position in sequential time steps t = 0, … , T, which are given at 00, 06, 12 and 18 GMT. The initial position is considered the first detected maximum of relative Vorticity. During the cyclone detection and tracking method, different threshold values are commonly applied to eliminate, for instance, the weakest centers and short living systems. For this reason, the threshold of equal or greater than 8 time steps (3 days and more) is considered based on Alijani (1366) to eliminate short living cyclones.
In this study, climatology of cyclones such as genesis and lysis centers, tracks and frequencies in the Mediterranean Basin and Middle East were analyzed. The results showed that, center and eastern part of the Mediterranean region include Aegean Sea, Cyprus, and northern borders of Mediterranean Sea, Adriatic Sea and also Red Sea, Sudan and Iraq, are most important cyclogenesis centers in winter season.
These cyclones which form in these cyclogenesis centers, move to the east with two eastward and northeastward distinguished directions. In northwest of Iran, the cyclones by passing over West and East Azerbaijan and Ardebil provinces in eastward and northeastward directions, move into western and southern shores of Caspian Sea. In southwest of the country, the cyclones are entered into Iran over Khozestan, Chaharmahal and Kohkilouyeh provinces. Part the cyclones are moved into center and northeast of the country with northeastward direction and other part by crossing over southern shores of the country move to the southeast of the country. In mid-west of the country, the cyclones are arrived into Iran in three different tracks. The most important path is Kordestan's path which the cyclones in the origin of Mediterranean are entered eastward into Iran by crossing over Zanjan and Hamadan provinces, under the Alborz ranges are moved into east and northeast of the country. Two other paths are observed in Ilam and Kermanshah Provinces which in these tracks also the cyclones are approximately moved eastward into center and northeast of the country. The results also showed that eastern part of the Mediterranean region specially Cyprus, Aegean sea, Adriatic sea, Red sea and Sudan and also Iraq are most important wintertime cyclogenesis centers of Iran. The main entrance paths of the cyclones includes northwest, mid- west and southwest. The averages cyclones lifetime are 4.5 days, movement speed is about 20 km/h and also travelling length is about 1700 km. Of the other notable results we can refer to decreasing of the rain producing cyclones during 3 last decades. 

Yousef Ghavidel, , ,
Volume 5, Issue 1 (6-2018)

Climatic geography of Tropical Cyclone hazards Affective on the southern coasts of Iran
The occurrence of any climatic fringes, including annual tropical storms, leave irreparable risks in its dominated areas. Understanding these events and knowledge of the time of their occurrence can be helpful in managing the unexpected incidents caused by them. Tropical cyclones are important natural turbulent processes in tropical and middle ecosystems in a number of regions of the world. Among the dynamic conditions of the atmosphere for the formation of tropical storms, there are three basic conditions: 1. The vertical wind shear should be limited between the 850 to 200 mb and the wind speed between these levels should be less than 10 meters per second. Such a situation allows the formation of a straight column, without breaking, to initiate tropical storms. 2- The formation state of tropical storms should be such that at least it is five degrees of latitude distant from the equator. Such conditions provide the minimum of Coriolis force to provide the tropical cyclic rotation along with other fundamental and apparent forces of the atmosphere and they occur following the pressure forces, Coriolis and centrifugal forces, cyclostrophic winds, and cyclic circulation in the center of the low pressure. 3- The presence of turbulence or discordance with vorticity and the convergence in the lower troposphere, or the anticyclone rotation and divergence in the upper levels of the atmosphere before the onset of activity, and the formation of tidal disturbances. Tropical storms are created by the presence of various dynamic and thermodynamic factors such as sea surface temperature and moisture content (thermodynamic properties), and flow and vertical winding functions (dynamic characteristics).
The parameters studied in this study for the dynamic and thermodynamic analysis of the tropical rotation of 1948 generally included the mean sea level pressure, geopotential heights, zonal and meridional components of wind, convection available potential energy, convective stabilization index, vertical velocity, relative vorticity, Sea surface temperature, humidity, and cloud cover levels which are drawn from the European Center for Medium Forecast Scale (ECMWF) with spatial resolution of 0.75 applying GRADS software. The study of combinational maps of 500 milligrams of geopotential heights and vorticity advection on the first day of the cyclone (1948/06/05) indicates the presence of a very strong low-altitude center with seven closed curves on the Arabian Sea. The most inner curve of this low-altitude center has the lowest elevation with 5650 geopotential meters height and the maximum vorticity advection and downright negative velocity of 10 and 0.5 Pascal to seconds, respectively. The above-mentioned Jetstream map with a maximum speed of 16 m / s, which covers the east of the center of the altitude, contributes to the greater divergence of this system. The formation of a very strong negative eddy in the 500-mb equilibrium also indicates intense instability at the site of the tropical cyclone and is actually a factor in the formation and reinforcement of such cyclones .The above-mentioned low altitude continues its cyclonic rotation at the level of 850 mb with two closed curves, and the maximum vorticity advection and downright negative velocity of 16 and 0.6 Pascal to second, respectively, due to the presence of lower level radar with a maximum speed of 20 m / s on the south side and similarly, in the south-east, it continued to circulate more rapidly at a rate higher than 500 mb, which results in the formation of the first pressure packet with a central
pressure of 997.5 mb on the sea surface. The high amount of specific humidity of 850 mb from the start of cyclone activity (12 g / kg), and the increase in this parameter in the next days of activity reaches 14 g / kg and also 4.5 g / kg at 500 millimeter equilibrium point to the high humidity at the location of the low-pressure center and the optimum conditions for the extraction of heavy rainfall in the eye wall of cyclone. Cloud cover maps also indicate a climber air density of up to 500 mb and the formation of a cloud at different levels of the atmosphere at the site of the formation of tropical rotation. The results show that the formation of the lower Jetstream, along with the tropical cyclone event (from 05 to 08 of 1948) affecting the southern coast of Iran, has been able to create severe air mass divergences in the left half of the nucleus and following this mechanism and the relationship between this velocity nucleus and the lower levels of the atmosphere and the sea level in the vertical direction, with the convergence of the mass, has been accompanied with the reduction of density and, finally, the reduction of pressure and the formation of turbulence, as the first ring for the development of tropical cyclones; therefore, the altitude of 850 mb and jet stream located at this elevation affected by the high-rise phenomenon on the western shores of the ocean (sometimes in the east of Madagascar) is considered as one of the most effective dynamic factors for the birth and development of this tropical cyclone on the southern coast of Iran. The tropical cyclone was formed from June 5 to June 8, 1948, at approximately 16 degrees north and 60 degrees east on the Arabian Sea. And, in general, the interaction between high pressure tongues on Saudi Arabia, Tibet and Iran, and the tropical cyclones has prepared the conditions for the activity and displacement of the tropical rotation. Previous studies of tropical storms have considered other synthetic systems, such as cyclones over Europe, and the integration of cyclones on the Mediterranean and Oman, as well as the displacement of the axis of tropical cyclones at middle and upper levels of the atmosphere affective in the escalation and displacement of the storm. It is also believed that the southern coast of Iran is also effective, and in general, less attention is paid to the causes of the development of the storm.
Key words:Tropical Cyclone, dynamic and thermodynamic analysis, low level jet stream, Thermodynamic parameters, Southern coast of Iran

Mr Seyed Abdolhossein Arami, Professor Majid Ownegh, Dr Ali Mohammadianbehbahani, Dr Mehri Akbari, Professor Alireza Zarasvandi,
Volume 5, Issue 1 (6-2018)

The analysis of dust hazard studies in southwest region of Iran in 22 years (1996-2017)
Dust storms are natural hazards that mostly occur in arid and semi-arid regions and there are many harmful consequences. According to the topographic-climatic conditions in Iran and the significant increase in the number and severity of dust storms occurrence in recent decades, especially in the West and Southwest regions where the dust storms are the most important environmental crisis. Studying this phenomenon is necessary for better management its harmful effects.
Since most of the research are implemented as different case studies, and there is no comprehensive study that review a wide range of existing researches with overall results in the southwestern parts of Iran, in this study a comprehensive overview of available literature reviews are addressed including dust spatio-temporal variations, modeling, detection, and health issues.
This research is based on a library research and search of valid national and international scientific articles about the dust crisis and no data-processing. We attempted to analyze temporal and spatial variations in the south and southwest of the country using the available studies and the challenges of this phenomenon in the past and present to provide a new perspective to apply a comprehensive land management and managing environmental hazards in Iran with all the problems.
A review of the history of dust storm studies from information sources showed that most researchers (61.40%) used a synoptic method to study dust storms, and the most important indicators that were considered by the researchers in physical properties were frequency and density, 34.21% and 34.21% of the studies respectively.
Dust detection methods show that the use of thermal or reflective bands cannot detect dust phenomena with high precision, therefore, a model which applies both bands simultaneously should be developed. In other words, applying a combination of reflective and thermal
spectra of Military Origin Destination Information System (MODIS) could offer better
results in detection of dust storms in the study area. Studies indicate that most of the storms
originate outside of Iran. Moreover, exposure to airborne contaminants, especially when the
dust storms occur in the Middle East, can lead to an increase in the related disease outbreak
in the study area. For instance, there was a 70% increase in referring to medical centers for
lung related problems when a dust phenomenon occurred.
The Results showed that in cold seasons where low height and western waves is formed on the European and Mediterranean Sea, due to the heaviness, cold air in these days, can penetrate low latitudes and their trough is located over the Middle East area. Under warming condition, the front of rough is formed as ridge, then engendered turbulence and wind. In the warm seasons, thermal low pressure is rapt to ward in the high latitude, and severe dryness
of the area is also due to the fact that the dusty phenomenon is intensified in the area. Dust
storm occurrence in the summer due to bareness of the land, transparency of the atmosphere,
dryness of the air and the vast plains, which can reduce the formation of local instability in
the case of a sharp rise in air temperature. The dispersal of deserts and sand sea is mainly in
the northwest of Khuzestan province, especially in Fakkeh and Moussan which are located in the western borders of Iran with Iraq, which cover most of the Azadegan plain and west of the Karkheh and Mollasani and Maroon Rivers, and ultimately end in the Omidiyeh and Aghajari regions. Results show that the border between Syria and northwest Iraq, west and southwest of Iraq to east and northeast of Saudi Arabia are the main sources of dust in the studied region
. Synoptic conditions considering simultaneously with the occurrence of dust
storms showed the significant role of cyclonic systems in the occurrence and transfer of this
phenomenon. With the phenomenon occurrence during the warm period, the significant
strengthening in low pressure of Iraq along with the trough formation in Zagros causes the
formation and transfer of dust towards Southwest Iran. Simulation studies of dust particles
movement paths have shown that most of the paths are from the northern and central parts
of Iraq and Syria and the source of dust storms are deserts and dry regions of the northern
and central parts of Iraq and Syria. In addition, the study of the transmission paths of particles
in dust storms indicates the presence of a lower level jet, which causes horizontal
displacement of dust particles in a shallow layer and prevents its vertical propagation in the
higher layers of the atmosphere. In general, although the dust phenomenon is transnational
and uncontrollable, it can introduce limitations in terms of circulation patterns and statistical
properties at different time intervals to the different planners via its time and scope which
will necessitate appropriate programs for combating and adaptation.
Keywords: Dust, Air pollution, Spatio-temporal pattern, Southwest, Iran.

Zahra Hejazizadeh, Meysam Toulabi Nejad, Zahra Zarei Chaghabalaki, Behzad Amraeei,
Volume 5, Issue 4 (3-2019)

This research was conducted to identify the dust storms in the Midwest of Iran from June 16 to 19, 2015. To investigate the synoptic conditions of the causes of this phenomenon, the ECMWF has an array of 0.125 degrees, including geopotential, omega, and sea level pressure, orbital and meridian components of the wind, specific humidity Soil moisture was applied to a depth of 10 cm. Similarly, for the purpose of routing the source of dust particles, the model of the Minimum Meteorological Parameters (HYSPLIT) Marv was used. The results of this study showed that in Lorestan province, non-ditches created by low-pressure thermal springs and high-altitude movements in Saudi Arabia caused the convergence and sucking of flows to the west of the country, as well as the establishment of a low-pressure cut at the middle levels of the atmosphere in the east of the Caspian. In the event of this risk, it has been effective. According to the average soil moisture from the surface of the earth to a depth of 10 cm in days with dust hazards, the moisture content of dust particles in the dust was less than 15%, due to the flow of streams from these fields without sufficient moisture, fine particles the soil is easily directed towards the study. A survey of Hysplit tracking maps shows that two general paths for the transfer of dust to the studied region can be detected. 1-Northwest - Southwest At an altitude of 1500 meters: passing through the dust nuclei formed in the northwest of Iraq and east of Syria, carry out the transfer of dust to the west-west of Iran. As these currents have been able to transfer dust to the southwest of Iran, this path can be considered the main route of dust dispersion to the region. 2- The western-eastern route at an altitude of 500 to 1000 meters: is the source of particles of this route inside the country (around Hurralazim) that entered the West of Iran and greatly reduced the horizontal visibility, which is the main source of dust on June 18 and 19. The investigation of the path of dust particles in the walnut shows that these particles were initially transferred to lower levels by low-pressure systems in the Midwest of Iran and then pulled in three directions on the ground.

Mr Masoud Jalali, Mr , Mr Abdullah Faraji, Mr Ali Mohammad Mansourzadeh, Mr Sayyed Mahmoud Hosseini Seddigh,
Volume 6, Issue 4 (2-2020)

Analysis and zoning of thermal physiological stresses in Iran
Human health is influenced by weather variables in all circumstances, including atmospheric pressure, humidity and temperature around them. Based on climate hazard and climate changes, different parts of human life and economic and social strategies such as health, hydrological pollutants And agriculture had a profound effect, including the discussion of the effects of thermal stress on human health over the last few decades, and has become a major issue in the world's scientific circles. Heat and cold stresses, the exposure of humans to extreme heat and cold, are part of the extreme events, often encountered by people during daily activities or in the workplace, and affecting human physical activities. It is important that, if the body is not cooled through transpiration or cooling mechanism, severe deaths are inflicted on human health; therefore, the person has to reduce his activity in order to reduce the adverse effects of heat stress. Hence, many researchers consider the thermal stress component more important than other components in assessing human health.
In this study, using the physiological equivalent thermometer of PET thermal stress assessment and zoning of human thermal physiological stresses in Iran, with the length of the common statistical period from 1959 to 2011, and for the arsenal of thermal physiological stresses of Iran Forty stations have been used as representatives of Iranian cities. To calculate the physiological equivalent thermal temperature, all the effective meteorological elements in the human energy bill are measured at an appropriate height of climate biology, such as 1/5 meters above the Earth's surface. Data on climatic elements are provided by the Meteorological Organization of Iran. In the absence of data for some courses, linear regression method was used to reconstruct these missing data. After calculating the indices, the frequencies were also monitored and finally, using the GIS technique, the Kriging method of the study area was based on the frequency of occurrence of the indicators. Therefore, in order to achieve the results and objectives of the present study, software such as SPSS for data normalization as well as missing data was analyzed and analyzed using Ray Man's model based on meteorological elements to calculate the equivalent thermal physiological temperature of humans. Also, using the GIS software and Ordinary Kriging method, the best interpolation method was used to zon the human cysiological stresses.
Today, in the planning of human health and comfort, the study of the physiological thermal stress plays an important role. In this regard, weather conditions can be used in the long-term planning of climate and in the short term planning of atmospheric conditions. In the present study, using the thermophysical Thermal Equivalent Thermal Index (PET), the climate climatic Atlas of Iran was prepared on a monthly basis. Calculated values for 40 stations in the country with a total statistical period of 52 years (1959-2011) were prepared. The results of this study showed that the spatial distribution of the physiological equivalent thermal temperature index in the country follows the altitudes, roughness and latitude. Accordingly, the low values of the indicator, which relate to the stresses of the cold, are consistent with the high and mountainous regions as well as the high latitudes, and vice versa, the thermal stresses occur in low and low elevations, as well as low latitudes, which of course, severe heat stresses occurred in the summer. Because throughout this season, the entire country of Iran is dominated by high tidal altitudes at high and low levels of ground pressure (1000 hp) with its warm and dry air, causing extreme heat and The term effects of heat waves on humans, heat loss, thermal contraction of the muscles and skin dryness, infectious or skin diseases, inflammation, sunburn, dizziness, fatigue, and mortality due to an increase in allergies can be mentioned. Significant differences in the environmental conditions of the mountainous masses of Kerman, Yazd and Sistan and Baluchestan provinces with their surrounding areas or low and low northern areas, and especially the Moghan Plain and Sarakhs plain, located in the upper latitudes of the country The issue is that the role of elevation in spatial distribution of the country's climate is much more colorful than factors such as latitude and longitude. The results of the analysis of the monthly thermal physiological stress maps showed that in terms of the area without tension, the march of the month with 47/8% of the area (778424/2km2) is in the first place and has the most favorable environmental conditions, The moon with 43/5 percent of the area (709275/2km2) is in the second position and also in March with 22.6 (359128/9km2) in the third, August and the last month. The highest thermal stresses (29
Dr Hassan Lashkari, Miss Neda Esfandiari,
Volume 7, Issue 2 (8-2020)

Identification and synoptic analysis of the highest precipitation linked to ARs in Iran
        Atmospheric rivers (ARs) are long-narrow, concentrated structures of water vapour flux associated with extreme rainfall and floods. Accordingly, the arid and semi-arid regions are more vulnerable to this phenomenon. Therefore, this study identifies and introduces the highest precipitation occurred during the presence of ARs from November to April (2007-2018). The study also attempted to demonstrate the importance of ARs in extreme precipitation, influenced areas and identifies the effective synoptic factors. To this end, integrated water vapour transport data were used to identify ARs, and documented thresholds applied. AR event dates were investigated by their daily precipitation, and eventually, ten of the highest precipitation events (equivalent to the 95th percentile of maximum precipitation) associated with ARs were introduced and analyzed. The results showed that most ARs associated with extreme precipitation directly or indirectly originated from the southern warm seas. So the Red Sea, the Gulf of Aden and the Horn of Africa were the major source of ARs at the time of maximum IVT occurred. Synoptically, seven AR events formed from the low-pressure Sudanese system and three events from integration systems. The subtropical jet was the dominant dynamic of the upper troposphere, which helped to develop and constant of ARs. Moreover, the predominant structure of jets had a meridional tendency in Sudanese systems, while it was a zonal orientation in integration systems. The intense convective flows have caused extreme precipitation due to the dominance of strong upstream flow besides having the highest moisture flux. The station had the highest precipitation has been located in the eastern and northwestern region of the negative omega field or upstream flows.
        Keywords: Identification and synoptic analysis, highest precipitation, Ars, Iran.

- Shiva Gharibi, Dr Kamran Shayesteh,
Volume 8, Issue 3 (12-2021)

Application of Sentinel 5 satellite imagery in identifying air pollutants Hotspots in Iran
Shiva Gharibi1, Kamran Shayesteh2
1- PhD Student of Environmental Science, Malayer University, Malayer, Iran.
2-Assistant professor, Department of Environmental Sciences, Faculty of Natural Resources and Environment, Malayer University, Malayer, Iran
Extended abstract
1- Introduction
Today, poor air quality is one of the most important environmental problems in many cities around the world. Air pollution can have a devastating effect on humans, plants, organisms, and human assets, and efforts are being made to anticipate and analyze the amount of distribution and transmission of air pollutants in order to minimize the adverse effects on air quality and climate. Among the most important air pollutants are (CO), (SO2), (NO2), (O3) and aerosols (AI). Numerous studies have been conducted on the monitoring of these pollutants based on information and statistics from pollution monitoring devices, but the use of satellite images in the field of monitoring and measuring pollutants has been limited. Due to the increasing growth of these pollutants, in this study, an attempt has been made to identify the average spatial concentration of the most important air pollutants as the actual sources of pollution on the scale of Iran from October 2018 to December 2019. Also, identifying the most polluted centers in Iran based on the average of 5 pollutants is another goal of this study. Therefore, the aim of this study is to demonstrate the ability of Sentinel satellite to monitor air pollutants, and the ability of GPW images to produce a population density map for the first time on an Iranian scale.
2- Methodology
 Using the Python programming language in the Google Earth Engine program environment, various products related to CO, SO2, NO2, O3 and AI pollutant images, obtained from Sentinel-5 satellite images during the study period and in the scale of Iran, were obtained for monitoring of air pollutants and determination of pollutants focuses. The output variable is defined as a set of images based on the time filter (2019) and the spatial filter (Iran borders). The output of the average concentration of pollutants for each month is calculated separately and annually in these filters. Then, the spatial map of the average concentration of pollutants in the Arc map software was analyzed and statistical information related to the average concentration of these pollutants was processed by SPSS statistical software. To determine the hotspots in terms of all pollutants, the raster location map of each pollutant was classified using the Jenks algorithm. In order to identify the share of provinces and counties, the amount of pollutants was also analyzed by spatial statistics in GIS environment and using the Zonal Statistics command based on the defined administrative boundaries. The G statistic was used for Cluster analysis, and in order to identify Hot Spots and Cold Spots, Getis-Ord Gi statistic (Gi) was used in GIS environment.To determine the population of each province, the latest census information of Iran as well as satellite images related to the fourth version of Gridded Population of World (GPW) product were used. Finally, The Moran index was used to determine the pattern of pollutants distribution and the spatial autocorrelation.
3- Results
 Spatial output from the processing of Sentinel-5 satellite images during the study period for identifying air pollution centers in Iran showed that the highest levels of nitrogen dioxide were recorded in the majority of cities in Tehran and Alborz provinces and then in the centers of other provinces. In the case of carbon monoxide, the highest rate is in Tehran and the coasts of the Caspian Sea and Khuzestan, and coastal areas of Bushehr and Hormozgan provinces. The highest amount of ozone is in the northern parts of the provinces of West and East Azerbaijan, Ardabil, Gilan, Mazandaran, Golestan and Northern Khorasan. Most of the dust was in the southern, eastern, southeastern and central provinces of Iran. The highest amount of sulfur dioxide pollutants is recorded in Tehran and then in the provinces of Khuzestan, Kerman, Hormozgan, Bushehr, Markazi, Qom, Isfahan and Khorasan Razavi. Provincially, the highest share of nitrogen dioxide is in the provinces of Tehran, Alborz, Qazvin and Qom. The highest provincial share of carbon monoxide is in Khuzestan, Gilan and Mazandaran provinces. The highest share of dust is in the southeastern provinces, including Sistan and Baluchestan, the highest share of sulfur dioxide is in Khuzestan province, and the highest share of ozone pollution is in the coastal provinces of Caspian Sea. Compliance of the average 5 pollutants with Google Earth images showed that the contaminated areas are located in the cities of Abadan, Imam Khomeini Port, Mahshahr Port and Ahvaz (Khuzestan Province), Tehran, Pakdasht (Tehran Province) and Assaluyeh Port (Bushehr Province). The results of comparing the average concentrations of pollutants in different seasons showed that there was no significant difference between CO, NO2 and O3 pollutants in different seasons, but suspended particles and aerosols in winter and autumn seasons have a significant difference with the amount of this pollutant in spring and autumn. Also, SO2 pollutant in autumn had lower concentrations than other seasons. The results of clustering analysis to determine the status of significant spatial clusters showed that the data are in the confidence range and have spatial auto-correlation and cluster distribution pattern.
4- Discussion & Conclusions
 According to Sentinel-5 satellite images, most of the pollution centers in Iran are related to petrochemical industries and refineries, which are located in the cities of Abadan, Imam Khomeini port, Mahshahr port and Ahvaz (Khuzestan province), Assaluyeh port (Bushehr province) and common pollutants. By these centers are NOX, SO2, CO, suspended particles and aerosols. Also, other centers (Tehran, Pakdasht in Tehran province) are located in the most populous urban areas of, which have been identified as hotspots in high production of NO2 and CO, due to high population and urban traffic.  Due to the higher population density of Tehran and Pakdasht than other cities in Iran, air pollution can be more important in these cities. Therefore, the use of satellite imagery to monitor Iran's air pollutants and the location of hotspots can be very cost-effective and time-consuming.
Keywords: Air Pollution Monitoring, Sentinel, Satellite Imagery, Polluted Hotspot, Moran’s Index.
Seddigheh Farhood, Asadollah Khoorani, Abbas Eftekharian,
Volume 10, Issue 2 (9-2023)

In recent years, research on climate change has increased due to its economic and social importance and the damages of increasing extreme events. In most studies related to climate change, detecting potential trends in the long-term average of climate variables have been proposed, while studying the spatio-temporal variability of extreme events is also important. Expert Team on Climate Change Detection and Indices (ETCCDI) has proposed several climate indices for daily temperature and precipitation data in order to determine climate variability and changes based on R package.
Various methods have been presented to investigate changes and trends in precipitation and temperature time series, which are divided into two statistical categories, parametric and non-parametric. The most common non-parametric method is the Mann-Kendall trend test. One of the main issues of this research is the estimation of each index value in different return periods. The return period is the reverse of probability, and it is the number of years between the occurrence of two similar events (Kamri and Nouri, 2015). Accordingly, choosing the best probability distribution function is of particular importance in meteorology and hydrology.
Despite of the enormous previous studies, there is no comprehensive research on the estimation of extreme indices values for different return periods. Accordingly, this study focuses on two main goals: First, the changes in temperature and rainfall intensity are analyzed by analyzing the findings obtained from extreme climate indices (15 indices) and then (second) estimating the values of the indicators for three different return periods (50, 200 and 500 years).
Data and methods
In this research, the daily data of maximum, minimum and total annual precipitation of 49 synoptic stations for 1991-2020 were used to analyze 15 extreme indices of precipitation and temperature. Namely, FD, Number of frost days: Annual count of days when TN (daily minimum temperature) < 0oC; SU, Number of summer days: Annual count of days when TX (daily maximum temperature) > 25oC, ID, Number of icing days: Annual count of days when TX (daily maximum temperature) < 0oC; TXx, Monthly maximum value of daily maximum temperature; TNx, Monthly maximum value of daily minimum temperature; TXn, Monthly minimum value of daily maximum temperature; TNn, Monthly minimum value of daily minimum temperature; DTR, Daily temperature range: Monthly mean difference between TX and TN; Rx1day, Monthly maximum 1-day precipitation; Rx5day, Monthly maximum consecutive 5-day precipitation; SDII Simple precipitation intensity index; R10mm Annual count of days when PRCP≥ 10mm; R20mm Annual count of days when PRCP≥ 20mm; CDD. Maximum length of dry spell, maximum number of consecutive days with RR < 1mm; CWD. Maximum length of wet spell, maximum number of consecutive days with RR ≥ 1mm. Finally, the trends of indices were estimated using the non-parametric Mann-Kendall test and the values of these indicators were estimated for 50, 200 and 500 years return periods.
In order to calculate values of each indicator for a given return period, the annual time series and its probability of occurrence are estimated and the most appropriate statistical distribution function that can be fitted on the data is selected from among twelve functions. In this estimation, EASY-FIT (a hydrology software), which supports a higher range of distribution functions, is used. The intended significance level for 500, 200 and 50 years return periods were 0.998, 0.995 and 0.98, respectively. The functions used in this research include: Lognormal (3P), Lognormal, Normal, Log-Pearson 3, Gamma (3P), Gumbel, Pearson 5 (3P), Log-Gamma, Inv. Gaussian, Pearson 6 (4P), Pearson 6, Gamma. Kolmogorov–Smirnov test is used to assess the goodness of fit of the estimation from three return periods.
The results indicate that while the trend of precipitation indices except for the Maximum length of dry spell (CDD) is decreasing, the trend of temperature indices was increasing, except for two indices of the days with daily maximum and minimum temperatures below zero degrees. From a spatial perspective, hot indices in the northwestern regions, cold indices in the southern half of the country shows an increasing trend, and the Caspian Sea, Oman Sea, Persian Gulf coastal regions, and the Zagros foothills are the most affected areas as a result of the increasing trends. Also, the index values were estimated for 50, 200 and 500 years return periods. As a result of the investigations, for temperature indices the north-west of the country has the highest values by different return periods. The increase in the values of R10, R20, RX1day and RX5day indices in the different return periods was more in the Zagros and Alborz mountain ranges, and the CWD, CDD and SDII indices have the highest values in the Caspian Sea and Persian Gulf Coastal areas.

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