Climatology
Ali Ghasemi Beqtash; Ali Mohammad Khorshiddoust; Khalil Valizadeh Kamran
Abstract
Introduction Today, there are many factors involved in air pollution. PM10 is one of the significant elements influencing air pollution in the city. Due to their fineness, these particles can travel to high altitudes and long distances. The metropolis of Tabriz is known as one of the polluted cities ...
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Introduction Today, there are many factors involved in air pollution. PM10 is one of the significant elements influencing air pollution in the city. Due to their fineness, these particles can travel to high altitudes and long distances. The metropolis of Tabriz is known as one of the polluted cities whose air pollution is caused by burning a huge amount of fossil fuels, lack of green space and topographic and climatic conditions. Given that the purpose of synoptic studies is to explain the key interactions between the atmosphere and the surface environment, and synoptic climatology pursues a major goal and that is to find the relationship between atmospheric circulation and the surface environment. Given the importance of the phenomenon of dusty air pollution and on the other hand its widespread spatial expansion in recent years in the northwest, the need for this research was felt more than ever; Therefore, in this study, suspended particles in the atmosphere have been analyzed as one of the most important air pollutants in Tabriz Materials and Methods In order to investigate the effect of active pressure patterns on pollution in Tabriz metropolis, the synoptic analysis method was used. In order to influence the meteorological conditions on increasing and decreasing pollution, pressure gauging meters have been used in connection with the main PM10 pollutant. To achieve this goal, the average daily data of PM10 in the years 1992-2010 in Bagh Shomal station and meteorological data of Hamidid station in Tabriz have been used. The method was as follows: the data were first entered into Excel software and based on the standard table of air quality, the standard limit of pollutants was determined. Extreme contaminated days were filtered and extracted by Excel. Polluted days with dangerous conditions on March 15-16, 2009 and to May 6 the same year. Then using the surface pressure data, the level of 500 hPa of pressure patterns on the infected far days were analyzed. The study of air quality index showed that the highest number of polluted days occurred in 2008 and the lowest number of dangerous polluted days occurred in 2006. In addition, the highest number of dangerous polluted days occurred in March, May, April and June. The results of the study of synoptic patterns show the existence of a weak pressure cells at the level of 500 and the dominance of a strong low pressure system at ground level and the distribution of temperature along with the hot core over the region. Also, the effect of the condition of the upper levels of atmosphere on the contaminated days by drawing synoptic maps of 500 hPa on the polluted days were examined. The Lund correlation method was used to select the representative days of the groups obtained from the classification of atmospheric pressure data. In this way, to select the representative day, the day that has the most similarity with the most number of group days was selected. Findings and Discussion The correlation coefficient represents the degree of similarity of the patterns of the two maps with each other. To do this, a certain threshold correlation coefficient must be accepted. The value of correlation coefficient in such cases typically varies between 0.5 to 0.7. Representative days were extracted based on a threshold of 0.5. Thus, the day that has a correlation coefficient of 0.5 with more days was selected as the representative day. The 500 hPa pattern, which has changed the climate of Northwestern Iran, is a Rex-type blocking system. Such a system is called lateral lifting Rex. After re-combining the western current in the east of this system, hot and dry conditions are applied to the area under their coverage. From the Northwestern region of Iran, in the impact basin of the low eastern part of this Rex system, which is mentioned outside the combined flow; Therefore, the unstable conditions in the study area are due to the positive rotating tawny wind of this arrangement from the lateral Rex system. In the case of west and east winds, the type of flow is important because their flow can be orbital or meridional. The wave motion of the winds in the meridional direction causes cold air to accumulate and fall inside the vessels within the higher latitudes to the lower latitudes, and vice versa, in the ridges, the warm air of the lower latitudes ascends to the higher latitudes. Orbital component maps show the direction of the wind (if the direction of the wind is negative and if it is positive in the direction of the west) and the speed of the orbital winds. The meridional component shows the wind speed in the north direction (if the wind speed values are positive) and south (if the wind speed values are negative). The wind map on the first day of pollution shows that the current The wind blows in a counter-clockwise direction in the low-lying center of the Mediterranean and at the same time in Northwestern Iran it moves in a counter-clockwise direction (anticyclonic) and increases pollution in the metropolis of Tabriz, but on the last day it gets west-east and The severity of pollution in Tabriz metropolis is gradually decreasing. Conclusion Given the importance of the phenomenon of dusty air pollution and on the other hand its widespread spatial expansion in recent years in the Northwest, the need for this research was felt more than ever; Therefore, in this study, suspended particles in the atmosphere, which is one of the most important air pollutants in Tabriz, has been analyzed. Examination of the air quality index of Bagh Shomal station in a period of study showed that the highest number of polluted days occurred in 2008 and the lowest number of dangerous polluted days occurred in 2006; but based on the persistence index and the average, days polluted with the dangerous condition of suspended particles were analyzed. According to the air quality index, the highest number of dangerously polluted days occurred in 2008 and in March, May and April. The hot core is on the area. Also, the effect of the condition of the upper levels of atmosphere was studied by drawing synoptic maps of 500 hPa on the polluted days. From the polluted middays, the two time periods of March 15 to March 17, 2008 and May 15 to May 17, 1988 were analyzed due to the continuity of the three days and the results indicated that there was a direct correlation between airborne synoptic circulation patterns and the polluted days in Tabriz. The main source of dust entering the metropolis of Tabriz during two periods with severe pollution of the deserts of Central Asia and Afghanistan. In addition this study showed that high air pressure, especially in the morning in autumn, causes an increase in the density of pollutants on the ground.
GIS&RS
fakhry sadat fateminiya; behrouz sobhani; Seyed Abolfazl Masoodian
Volume 23, Issue 69 , December 2019, , Pages 213-231
Abstract
Satellite images as new tools, provide new dimensions for land monitoring. In this study, in order to determine the homogeneous geographical areas in terms of leaf area, the remote sensing images of the Terra-Aqua Modis during the period of 2002-2016 with a spatial resolution of one kilometer and 8 days’ ...
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Satellite images as new tools, provide new dimensions for land monitoring. In this study, in order to determine the homogeneous geographical areas in terms of leaf area, the remote sensing images of the Terra-Aqua Modis during the period of 2002-2016 with a spatial resolution of one kilometer and 8 days’ time interval used.Leaf area was Zoning and analysis using the Matlab software and the Google Earth database. For this purpose, first, the mosaic and determination of the territory of Iran in the satellite data set of the Modis was determined. Then, a database in the field of cluster analysis, choropleth zoning created. Long-term mean temperature and precipitation data were also used in order to better understand the range of the leaf area. According to this analysis, 39.9 percent of Iran's vast vegetation is governed. The four zones identified in the country are the large, massive, moderate, and narrow areas. These four domains are respectively 0.89, 0.001, 3.31, and 35.76 of the land. The results showed that in all studied areas, the leaf area had a higher percentage during The warm period of the year due to the high temperature in this period and the presence of precipitation in the early cold season. The northern slopes of the Alborz, Hyrcanian forests, Golestan forests, Arasbaran forests are areas where there are different regions in all zones. In addition to forests, the areas identified for each generally include fields.
Climatology
Mostafa Karimi; Faramarz Khoshakhlagh; ali akbar shamsi por; fahimeh noruzi
Volume 23, Issue 69 , December 2019, , Pages 233-255
Abstract
Large-scale circulation patterns are controlling climatic conditions and especially precipitation of the area. The purpose of the study is investigating the relationship between circulation patterns of Arabian subtropical anticyclone and Iran precipitation. For this reason, was used re-analysis data ...
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Large-scale circulation patterns are controlling climatic conditions and especially precipitation of the area. The purpose of the study is investigating the relationship between circulation patterns of Arabian subtropical anticyclone and Iran precipitation. For this reason, was used re-analysis data of geo-potential height form European Center for Medium-Range Weather forecasts (ECMWF), with spatial resolution of 1*1 degree and correlation distance cluster analysis. Circulation patterns at 30 to 80 degrees the East longitudes and5 to 30degrees north latitudes and the period of11years (2000- 2010) was calculated. The results showed that the patterns in terms of occurrence were divided the patterns of the cold period, the warm period and the transition period. During the cold period anticyclone is located at down latitudes on the Arabian sea and Gulf of Aden and have precipitation more areas of Iran that maximum amount of precipitation is related to the second pattern. In the patterns of transition period Arabian anticyclone sent a southwest clockwise current in to the trough East Mediterranean is effective in the occurrence of precipitation in the area of North and Northwest of the country. In the patterns warm period the anticyclone caused the anticyclone conditions on country and has been as a barrier to entry precipitation systems.
Geomorphology
Hadi Nayyeri; Mohamad Salari
Volume 22, Issue 64 , September 2018, , Pages 289-310
Abstract
The study, according to the importance of tectonic – geomorphology studies, deals with the assessment and classification of active tectonic of watershed in Kurdistan province with a comparative – quantitative approach based on the parameters of drainage network. The study includes quantitative ...
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The study, according to the importance of tectonic – geomorphology studies, deals with the assessment and classification of active tectonic of watershed in Kurdistan province with a comparative – quantitative approach based on the parameters of drainage network. The study includes quantitative estimation of parameters associated with tectonic drainage network and the use of hierarchical cluster analysis.The research findings showed that the studied basins are classified, tectonically active, in two different clusters. Relative comparison between the clusters show that the basins located on the first cluster have more tectonic activity with more different slopes.In this regard, the second cluster basins have less tectonic activity, more homogeneous and forming faster-cluster threshold.According to the results, it seems that the situation of the first cluster basins, with the higher tectonic activity, are due to their spatial distribution and, consequently,their impressionable of different tectonic focus particularly active faults. Also, the situation of the second cluster basins is interpreted with respect to their more homogeneous spatial position corresponding to the central region of the study area and slower activity of Sanandaj – Sirjan zone.
Climatology
Masoud Jalali; Ali SHahbai; Vahab Kamrian
Abstract
In this paper, we attempted to identify the synoptic patterns of Summer heavy rainfall in the southern coast of the Caspian Sea by using environment- to- circulation method. To attain this aim , by using statistics of daily Precipitation of 40 synoptic and climatology stations located in the region for ...
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In this paper, we attempted to identify the synoptic patterns of Summer heavy rainfall in the southern coast of the Caspian Sea by using environment- to- circulation method. To attain this aim , by using statistics of daily Precipitation of 40 synoptic and climatology stations located in the region for periods of 20 years of 1991 to 2010 and by percentile method , 29 days have rain more than 15 mm which have occurred in at least 30 percents of region stations , were determined as days with heavy rain. By using factorial analysis and cluster analysis methods , 3 synoptic patterns were determined as agent of creating rain in 29 days that the first pattern 48.3 percent , second pattern , 30 percent and the third pattern have allocated 21.7 percent of days of heavy rain in the studied region. In order to synoptic analysis of these patterns , maps of sea level pressure , 500 hectopascal level , omega (atmosphere vertical motions) , vorticity and moisture flows of level of 850 hectopascal related to two days before rain was used until rain day and finally it is determined that the main cause of occurring heavy summer rainfall in southern coast of the Caspian Sea is the penetration high-pressure system and after that formation of cool and moist northern flows as well as incidence of vast convection in the region. Each three patterns emphasize on occurrence of this condition and their difference is the place of deployment of high-pressure system and consequently the number of rainy days and severity of rain in these days.
Climatology
Hosein Asakereh; Mehdi Doostkamian
Abstract
The purpose of this study was to climate regionalization precipitation water atmospheric Iran. Therefore, the pressure data and specific humidity of the NCEP / NCAR database during 1950-2010 dependent of the United States National Atmospheric and oceanographic organization was extracted and analyzed. ...
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The purpose of this study was to climate regionalization precipitation water atmospheric Iran. Therefore, the pressure data and specific humidity of the NCEP / NCAR database during 1950-2010 dependent of the United States National Atmospheric and oceanographic organization was extracted and analyzed. For the calculation used software programming environment of Matlab and Grads software and Surfer software used to perform graphics operations. In the study for the perceptible water climate regionalization use from cluster analysis and in order evaluate the results, used of discriminant analysis. In the data archive mean and Coefficient of Variation precipitation water month review and analysis the method cluster analysis ward composition, than dendrogram graph recognized three regionalization climates: a) climate regionalization whit high precipitation water, b) climate regionalization whit median precipitation water. b) Climate regionalization whit low precipitation water. The result archives from discriminant analysis indict that 98.24% from of pixels doing so as true in relative group.
Climatology
Gholam abbas Fallah Ghalhari; Mehdi Asadi; Alireza Entezari
Volume 19, Issue 54 , February 2016, , Pages 235-251
Abstract
Climate classification and identifying the most effective factors and elements of each area is one way of understanding identity of the climate zones. Therefore, to identify Guilan climate mapping new methods such as factor analysis and hierarchical cluster were performed. For this, we used 20 climate ...
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Climate classification and identifying the most effective factors and elements of each area is one way of understanding identity of the climate zones. Therefore, to identify Guilan climate mapping new methods such as factor analysis and hierarchical cluster were performed. For this, we used 20 climate variables of the 16weather stations in the study area. Then, using interpolation method, a matrix with dimensions of 20×106 data was obtained. Climate mapping of the province with factor analysis showed that the climate of the province is made up of two factors. These two factors are: humid-rain–wind and temperature–cloudy factors. Results also indicated that these two factors explain 99.44 percent of the variance of the primary variables. The contribution of each factor was 64.49, 34.95 percent respectively. Finally, cluster analysis on two climatic factors identified three climatic regions in the provinces. These three regions are: moderate and humid, mountainous, semi humid and cold.
Majid Rezaee Banafshe; Hoseyn Hossein Alipour Ghazi; Fatemeh Jaffari Shendi; Majid Alimohammadi
Volume 19, Issue 53 , September 2015, , Pages 117-135
Abstract
In this study, the heavy rainfall of Northwest of Iranhas been analyzed using environmental circulation approach. Isohyte maps were depicted using Kriging method on 14*14 km pixels from 21/3/1961 up to 31/12/2004 (a17508× 533 matrix). Based on these interpolated data we selected super heavy rainfalls ...
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In this study, the heavy rainfall of Northwest of Iranhas been analyzed using environmental circulation approach. Isohyte maps were depicted using Kriging method on 14*14 km pixels from 21/3/1961 up to 31/12/2004 (a17508× 533 matrix). Based on these interpolated data we selected super heavy rainfalls for all in Northwest of Iran as a whole. Heavy rainfall and their locations have been detected from 00 to 1200 E and 00 to 800 N in the five this levels (1000, 925, 850, 700, 600 and 500 hPa level) at 00:00, 06:00, 12:00 and 18:00 UTC. The results of this study showed that four thickness circulation patterns play role in producing these super heavy rainfalls. In analysis of these precipitations one representative day was introduced for every circulation pattern. The analysis showed that the circulation patterns 2 justify the most of precipitations. These findings can play an important role in forecasting the precipitation and preventing from flooding in the region.
Seayed Abolfazl Masoudian; Fatemeh Jafari Shendi
Volume 18, Issue 50 , February 2015, , Pages 305-331
Abstract
In this study, heavy rainfall of northern low rainfall region has been analyzed using environmental to circulation approach. In order to analyze these types of rains, Asfezari rain data base is used. A base with daily ranfall includes 15992 days, from 1340.1.1 to 1383. 1437 daily precipitation maps of ...
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In this study, heavy rainfall of northern low rainfall region has been analyzed using environmental to circulation approach. In order to analyze these types of rains, Asfezari rain data base is used. A base with daily ranfall includes 15992 days, from 1340.1.1 to 1383. 1437 daily precipitation maps of northern low rainfall region were created using Kriging method. Mean daily precipitation data for this station has been used. Spatial resolution of these maps were 18 Km*18 Km. So 1406 pixels cover the northern low rainfall region and temporal and spatial behavior of precipitation could be represented by a 1406*362 matrix. We selected 100 days of the heavy rainfall from IRIMO data base. A cluster analysis was applied on this matrix and four different circulation patterns were actived. As a result, 100 occurrences of broad and heavy rainfall have been assimilated according to the sea level pressure, humidiy flux convergensy, stream function and front function exorbitance. Spatial configuration of these patterns showed that the main reason of these rainfalls had been the siberian and Black Sea unticyclones, troughs of Red Sea and Persian Gulf.
Ali mohammad Khorshiddoust; Ali asghar Shirzad
Volume 18, Issue 49 , November 2014, , Pages 101-118
Abstract
In this research we used multivariable statistical methods (cluster and discriminative analysis) with the purpose of the recognition of spatio-temporal differences of precipitation in similar areas. We used monthly precipitation of 35 synoptic, climatic, and rain-gauging station data records of Northern ...
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In this research we used multivariable statistical methods (cluster and discriminative analysis) with the purpose of the recognition of spatio-temporal differences of precipitation in similar areas. We used monthly precipitation of 35 synoptic, climatic, and rain-gauging station data records of Northern Iran including three provinces of Golestan, Guilan, and Mazandaran for 1995-2007 periods. For grouping and homogenizing the stations, we initially applied Ward cluster analysis method. Then we used discriminative analysis and Wilk’s Lambda for finding out the validity of cluster analysis calculations. Results obtained from cluster analysis with Euclid interval method indicated that 4 major clusters can be drawn according to the amount and the location of the precipitation in the study area. Discriminate analysis showed that 82.3% of the clusters in our analysis were valid and about 17.7% were incorrect. The Wilk’s Lambda method also proved the differences between the means.
Samaneh Mosayebi; seyead skandar Seydayee; Ali Zangabadi; Alireza Rahimi
Volume 18, Issue 47 , April 2014, , Pages 197-213
Abstract
Increasing young population along with unemployment rates compared to previous years is one of the most serious challenges, and controversial for employment in the country. Understanding the employment and unemployment condition, perceived strengths and weaknesses and deficiencies in the employment planning ...
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Increasing young population along with unemployment rates compared to previous years is one of the most serious challenges, and controversial for employment in the country. Understanding the employment and unemployment condition, perceived strengths and weaknesses and deficiencies in the employment planning and human development has necessary impacts. However, a major concern of the province of Esfahan is the issue of employment and unemployment and its consequences.
Therefore the issue of employment and unemployment in the province was studied, and the affective factors are explained in this field, in order assess to the possibility of developing a comprehensive management for employment in the Province. The main objective of the study is to clear social inequalities in the employment field with regards to distribution facilities in Esfahan Province. The application of 36 variables was used and these variables were reduced to 5 through factor analysis. Then the cities were divided into 4 homogeneous classes through cluster analysis. The research results indicate that there are severe imbalances in towns. Out of that Esfahan town had the best conditions of employment index, while Khansar town was in the last row being the excluded town.
seyead hossein Mirmousavi; Neda Khaefi; Hoshang Abakhti Gharoosi
Volume 18, Issue 47 , April 2014, , Pages 215-233
Abstract
Classification of weather and climate are important in affecting each region. One of the ways is to identify areas of climate information. In order to conduct this study, annual data from 22 synoptic stations in two provinces of Kermanshah and Kordestan for 12 climate variables during the 20-year period ...
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Classification of weather and climate are important in affecting each region. One of the ways is to identify areas of climate information. In order to conduct this study, annual data from 22 synoptic stations in two provinces of Kermanshah and Kordestan for 12 climate variables during the 20-year period (1989-2008) were used. To increase accuracy, seven synoptic stations from neighboring provinces were selected. After performing factor analysis in 22 stations related to climate change both in Kermanshah and Kordestan, the internal correlation of their results was examined which show that climate in these two provinces, was almost under the influence of 6 factors climatic. These 6 factors justify about 91 percent of climate behavior the study area. These factors include: temperature, precipitation, humidity, clouds, thunder, wind and dust. By applying a hierarchical clustering method and Ward integration method, the elements of climate stations were divided into 5 clusters.
Farnaz Pourasghar; Saeed Jahanbakhsh; Behrooz Sari saraf; Hooshang Ghaemi; Masomeh Tadayoni
Volume 17, Issue 44 , September 2013, , Pages 27-46
Abstract
This is a study of change in annual precipitation amounts and variability in southern part of Iran during 1974-2005. Southern part of Iran has been regionalized based on six factors in 183 stations using Principal Component Analysis (PCA) and Cluster Analysis (CA). The stations were grouped into four ...
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This is a study of change in annual precipitation amounts and variability in southern part of Iran during 1974-2005. Southern part of Iran has been regionalized based on six factors in 183 stations using Principal Component Analysis (PCA) and Cluster Analysis (CA). The stations were grouped into four individual clusters. Topography and latitude play an important role in determining boundaries between identified subdivisions and existence of spatial differences between them as well. Spatial variability and relationship between the precipitation series at 183 of stations were investigated by principal component analysis. A PCA of annual precipitation reveals five components that account for 68% of the total variance. The annual precipitation PCs are controlled by atmospheric circulation. Analysis of the results revealed that annual precipitation in south part of Iran is mainly related to Sudan and Mediterranean wave.
Saeed Jahanbakhsh; Fatemeh Jafary shandy; Fereshteh Hosseinalipourgazy
Volume 16, Issue 42 , March 2013, , Pages 113-138
Abstract
In order to identify synoptic super heavy rain patterns (precipitation exceeding 50 millimeters a day) in Azerbaijan region, the daily precipitation data of 23 rain gauges were studied by six-hour precipitation synopsis from 1963 to 2005. The data were analyzed through hierarchical clustering analysis, ...
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In order to identify synoptic super heavy rain patterns (precipitation exceeding 50 millimeters a day) in Azerbaijan region, the daily precipitation data of 23 rain gauges were studied by six-hour precipitation synopsis from 1963 to 2005. The data were analyzed through hierarchical clustering analysis, specifically Ward cluster analysis in GRADS, MATLAB, and SURFFER softwares to identify the relationship between the higher-atmosphere circulation patterns and super heavy rain events in the studied region. Results demonstrated three different active circulation patterns in the region, for each pattern a single representative day was introduced for super heavy rain events's analysis. The spatial alignment of the precipitation pattern points out a relationship between the temporal distributions of super heavy rain events in region with the latitude. Significant relationships are existent between EastBlack Sea-NorthMediteranehSea, and Black Sea trough pattern and super heavy rain events in the studied region. The results play an important role in the prediction of heavy rain events in the region.
