فهرست مطالب farahnaz khoramabadi

For this purpose, the data of 13 climatic variables in 14 synoptic stations in a period of 44 years (from 1977 to 2020) used and a 13x14 matrix (rows; climatic elements and columns; number of stations) was created. In order to generalize the station data to the area, a grid with 15x15 km pixel was formed in central Iran and a matrix with dimensions of 446x15 (rows; digital pixel and columns; number of stations) It was found that the basis of the calculations will be factor analysis with varimax rotation and cluster analysis with Ward integration. The results of measuring the relationship between altitude and climatic variables indicate that in Central Iran, there is a direct and significant relationship between these two factors. However, due to the influence of local and macro-scale climatic factors, this relationship is not the same throughout the area and sometimes creates climatic nesting. In addition, the results showed that the 4 main and effective factors that make the climate of central Iran are: precipitation, temperature, humidity and dust storm. These factors explain 86.2 percent of the climatic behavior of this area. So that the rainfall with 35 percent is the most important climatic element in this area, which often dominates in cold mountainous regions and high altitudes. The temperature is 27.3 percent in the central deserts and the sides of Lut desert in Kashan, Khourbiabanak, Lar and Bam. Humidity is effective with 15.3 percent in parts of hot and humid southern areas in Baft, Abadeh and even cold and humid northern areas in Daran, Isfahan. Dust storms with 8.8 percent are the least effective factor in the climate of central Iran, which are scattered in Khourbiabanak, Bafaq, Yazd, and Kashan

In recent decades, along with the physical development of cities and population increase due to immigration, heat islands, which are mainly the result of human made activities, have gained significant importance. So, the reduction of vegetation cover, the high consumption of fossil fuels, the emission of greenhouse gases and the use of inappropriate materials in urban construction have created the microclimate of a heat island above the metropolis of the world. Finally, it causes an increase in the land surface temperature, atmospheric stability, persistence and stabilization of pollutants and an increase in respiratory diseases. Today, by using remote sensing methods and using digital satellite images, it is possible to examine the land surface temperature with high accuracy and in a short period using MODIS sensors and Terra satellite images. Therefore, the main objective of the current research was to analyze the temporal and spatial variations of heat islands of Isfahan using the principal component analysis method. With this technique, it is possible to identify the seasons and months when the land surface temperature and the heat island increased. 

In this regard, the present research considered analyzing the temporal and spatial variations of this phenomenon in Isfahan during a period of 20 years (from 2000 to 2020 AD). To achieve this purpose, the land surface temperature (LST) data extracted by MODIS sensor and Terra satellite was used. These data are available for the whole world with a time resolution of 8 days and a spatial resolution of 1x1 km in a sinusoidal grid with dimensions of 1200x1200 km. Therefore, for Isfahan, 913 images were extracted from the MODIS sensor. Then, with the principal component analysis (PCA) method, the seasons and months that have the most influence on the occurrence of heat islands were identified and in order to analyze the trend of this phenomenon, the Mann-Kendall and the Kolmogorov-Smirnov tests were used.

The findings of the research indicated that the land surface temperature in the last 20 years in Isfahan had an increasing trend with a rate of 4%. However, this trend in the population and urban centers has been completely different from the surrounding areas of Isfahan. In terms of spatial distribution, the highest occurrence of heat islands has been registered in the eastern and southeastern parts (including Hassan Abad and Jolgeh) due to proximity to the hot deserts of Kavir-Lout, proximity to Sepiddasht, Varzaneh, Shahrak Ramsheh industrial towns and changes in the land use of agricultural to industrial and residential. also in the North-West region (including Mahmudabad and Isfahan city) due to the increase in man-made heating caused by the increase in the consumption of fossil fuels, the growth of residential, industrial and commercial units, temperature has risen. In addition, the results showed that the intensity of the heat island in winter is higher than in summer, and the most intense time of its occurrence was recorded in January and the least in November.

Isfahan is integrally affected by global climate conditions, but depending on the geographical location of each part of this province, the land surface temperature and the occurrence of heat islands are different, so that, eastern and central parts, adjacent to Kavir-Lout and close to industrial towns, have an increasing trend. Moreover, the southern parts have a decreasing rate of temperature and heat islands due to less urban population, larger agricultural lands and more vegetation. The increase in urbanization, migration, and the increase in fossil fuel consumption, the decrease in vegetation, the aggravation of drought, and the change in land use have a fundamental role in increasing the occurrence of this phenomenon.

Problems caused by climate change are one of the most important environmental crises and threats of human society, especially in urban environments. In the city of Tabriz and in recent years, due to the growth of the population, a lot of migration from other cities, traffic, the development of industries and production centers have caused an increase in the production and distribution of pollutants. Based on this, in this research, attention has been paid to the evaluation of the quality of dust occurrence in the years 2019 and 2018. The concentration of dust particles in different areas of the studied places varies depending on the geographical location, topographical, climatic conditions and also their origin, both internal and external. Based on the results obtained from the analysis of laboratory results and field studies, in the Tabriz region and during the research period, the concentration of lead metal in dust is moderate for adults and severe for children, and the risk of mercury metal for both the elderly and children. It has been intense. The adverse effects of cadmium metal have been very severe in children and adults. On the other hand, the high air temperature in the city center and the formation of thermal islands in it causes local winds from the suburbs to the city center. With the transfer of pollution from the suburbs to the city center by these winds, the pollution situation in the city center also increases.

Today, dust phenomenon is one of the dangerous phenomena in most countries of the world that, hot and dry country like Iran and even its western provinces in Kurdistan are witness to this phenomenon. For this purpose, dust data from ten synoptic stations used in a period of 20 years (2001 to 2021 AD) to investigate the risk of dust in this province. Using the factor analysis method, the months with the highest number of dusty days identified. Then, the Aerosol Optical Depth (AOD) obtained from the MODIS sensor and Terra satellite analyzed using the Google Earth Engine satellite image processing system. Finally, after validating the index with days with dust, the trend of this index investigated by the Mann-Kendall test method, and maps of temporal and spatial distribution of dust were drawn. The results indicate that the distribution of dusty days in this province affected by eight main factors, the first and second factors are explained respectively; 68 and 13.45 percent of the variance of the number of dusty days in the province. In addition, the months of April to September have the highest dust concentration that in the eastern half of this province; Saqez, Diwandara, Bijar, Qorveh, Dehgolan stations have a positive and increasing trend, and in the western half of the province, Marivan, Bane, Kamiyaran, Sarovabad and especially Sanandaj stations have a decreasing and negative dust trend. In addition, the results showed that, in recent years, larger area of the province has faced an increasing trend in the concentration of aerosols and especially dust. Moreover, the summer season has the highest density and concentration of aerosol conditioners, especially in the months of July and August in this province, and after that, the spring season ranks second. The increase for dust in these two seasons can be due to the establishment of Azores high pressure and the dryness of the air due to low surface humidity in Iran and neighboring countries. Therefore, the results of this research can help urban planners and community health custodians to build culture and improve the education of citizens in dealing with the dust phenomenon, improving environmental conditions, identifying the most suitable travel time and starting tourism activities in Kurdistan province.

Heat waves are among the most dangerous weather threats related to global warming and climate change. Two databases were used to predict the spatial changes in the intensity of heat waves in East Azarbaijan province. The daily data of the maximum temperature in 5 synoptic stations of the province inlcuding Tabriz, Maragheh, Jolfa, Ahar and Mianeh for the time period from 1981 to 2021 AD as the period of historical-base data were used. The output of the selected CanESM model under the dual economic-social scenario SSP1 is the result of the Coupled Model Intercomparison Project Phase 6 (CMIP6) in the future period from 2022 to 2065. The validation of the data of the basic period with the future period was done with standard measures and with the step-by-step regression technique, the intensity of heat waves in the province was explained. The results indicate that the intensity of heat waves will increase until 2065 in all the investigated stations and it will cover a large area of ​​the province. So, in the next half of the century, the intensity of heat waves in Tabriz will be 1.3 °C, in Maragheh will be 1 °C, in Julfa will be 0.7 °C, in Ahar will be 1 °C and in Mianeh it will be 1.4 °C. Moreover, with the warming of the earth's air due to the impact of global climate changes, smaller heat waves join together and will create more intense, bigger, and lasting heat waves. The results showed that with the decrease in latitude in this province and the proximity to low-lying and low-altitude areas, the frequency and intensity of heat waves will also increase.

Increasing global warming is one of the major global issues of the current century. For this reason, it is important for humans to study and evaluate its trend, so simulating this climatic variable can be a way to understand the human future. There are several methods for simulating and predicting heat waves, the most valid of which is the use of the general circulation model of the atmosphere and GCM. One of the most widely used models for GCM data miniaturization is the LARS WG statistical model. In the present study, the efficiency of this model for exponential micro-scale of heat waves in Julfa station was evaluated. To achieve this goal, daily statistical average maximum temperature above 35 ° C in a given statistical period has been used. Also, to predict the heat waves in the coming years, the maximum temperature data of the models (CESM CAM, CMCC CMS, CAN ESM, MPI ESM) under the RCP8.5 scenario for the next period 2011-2016 were performed. The results showed that heat waves in the future period (2011 2065) have a normal distribution compared to the base period. . Therefore, these results show the very good performance of the LARS WG model in simulating heat waves. Jolfa station heat waves in the base periods (1990-2020), with severe irregularity and variability of annual heat wave events, indicate a strong variability of the average annual temperature and a variety of factors affecting the temperature of the region. On the other hand, according to the forecast of MPI ESM, CESM CAM and CMCC CAM climate models, the temperature of the annual heat waves that go towards more heat in the warm period;

Precipitation is the most important hydrological variable that connects the link between atmosphere and surface processes. Three-quarters of the atmosphere heat is the result of releasing the latent heat of evaporation. Therefore, climatic zoning of autumn precipitation is necessary for achieving comprehensive development in different spatial-temporal dimensions. For this purpose, the daily data of autumn season at 18 synoptic stations of the study area have been analyzed with a joint statistical period 32 (1989 - 2018). In this study, Kolmogorov-Smirnov test was used to find out the normality of the data and Mann-Kendall test was used for the process of their changes. Then by applying factor analysis based on principal component analysis and with orthogonal rotation of Varimax it was found that there are two effective precipitation factors in the climate of the region which in total account for more than 68.16% of the variance of the region's autumn precipitation climate. By performing hierarchical cluster analysis and by integrating the matrix of factor scores, two main and sub-regions were identified. These areas are: Areas of high precipitation and moderate precipitation. It can be said that in the high precipitation areas of the territory are located on the rainy of the Zagros, Sahand and Arasbaran mountain belts, stretching as a narrow strip from the north to the south parts of the region.

Climate change on a large scale increases changes in boundary indicators. Since these indicators play an important role in the occurrence of droughts, floods and other climate disasters, it is necessary to study their behavior in the context of climate change. In the present study, 24-hour precipitation data of 11 Synoptic Stations during statistical periods (1987-2017) have been used. Climate change indicators (ETCCDI) have been used to extract trends using R-ClimDex software Also to check the linear trend of the test TFPW-MN and in order to zoning the precipitation conditions, PCA method has been used in the form of Minitab statistical software. The results of m-Kendall test show that precipitation indicators in all studied stations have a decreasing and negative trend and homogeneous slope. After forming the variable correlation correlation matrix, the principal components were reduced to 11 components using the analysis method and rotated using a varimax rotation. By examining the results of PCA algorithm, four climatic types were identified. The fourth climatic type (Shiraz station) has the most effective role in creating climatic conditions in precipitation with a relatively 85% specific variance of the total changes. As a result, it can be said that the overall structure of precipitation in the study area is affected by latitude, the existence of rough configuration and air masses. And by changing any of these factors, the rainfall will change.

Global warming is one of the current and future challenges for humankind which can have an impact on agriculture, transportation, water resources, energy production, architecture, heating and cooling needs of the building, plant phenology, etc. In this research, for the spatio-temporal analysis, the need for cooling day was used from daily data of minimum temperature and maximum temperature of 16 stations in the north east of the Iran during the period of 20 years (1996-2015). First, data matrices were created in the MATLAB software with an S-dimensional array (7035*16), where are the rows, representing time (day) and columns, representing the locations (stations). Finally, it was calculated of cooling degree day per month and plotted spatial mapping in ArcGIS. The results showed that significant and reverse correlation between altitude and latitude with cooling day requirements in all warm months of the year, also according to the need for cooling degree day, the Khorasan area can be divided into six climatic groups. The most need for cooling with more than 500 degrees of day is in the southern and lowlands of the area and the least need for cooling are located in the northern and highlands part. So that the highest percentage of need for cooling day degrees in April and May white %27.5, related to the semi-cold climate group; In June with %24.5; in July %23.7; in august %22.4 and in September whit %22.5, Belongs to the cold climate group. Also, the study of the process of cooling needs suggests that in April most of the stations lack a significant trend, and only stations in the north and south of the region have a declining trajectory. In September, there is also a drop in cooling needs at most stations.