فهرست مطالب مصطفی کریمی احمدآباد

In this study, the occurrence potential of rainfall-induced shallow landslides in the Babolrood basin has been investigated. In this basin, due to the mountainous topography and the presence of loose organic soils, the potential of such landslides is high, and landslides of different sizes occur every year after long and intense rainfalls. These landslides, which start with the sliding mechanism in the upper parts of the soil cover, immediately turn into earth/debris flows, and from their joining together, large flows may form downstream of the basin, which is considered a destructive phenomenon. In this research, to investigate the effect of rainfall on the occurrence of shallow landslides and flows, the TRIGRS program, which is a comprehensive and grid-based program for slope stability analysis using the infinite slope method, has been used. In this program, the effect of rainwater penetration into the soil and runoff caused by rainfall, which are important parameters in the occurrence of shallow landslides and subsequent flows, are also fully considered and this natural phenomenon is fully simulated. The input data required for this research includes topographical data of the basin, geological and hydrogeological properties of soil units, and rainfall data in the region, which are prepared in the form of appropriate text files and GIS maps. The output of the Triggers program includes maps of the spatial distribution of the minimum safety factor, the depth of the failure, and the pore water pressure at the failure depth, which are prepared in the form of text files and can be interpreted in GIS-based software. The results of this study showed that in the high and steep parts of the basin, wherever there are soils on a bedrock rich in clay minerals (such as mudstone, marl, and shale), the potential for shallow rainfall-induced landslides is high. In the field studies, a good agreement between the results of this study and the experiences obtained from field observations of landslides caused by rainfall in the region was obtained in terms of their spatial distribution and time of occurrence.

Landslides after floods and earthquakes are one of the most important natural hazards in the world, which cause many human and financial losses every year. Swadkoh region in the northern slopes of Alborz has been prone to landslides due to climatic, geomorphological, geological, hydrological and human-biological factors. The purpose of this research is to analyze the risk of landslides to identify the physical development limits of rural settlements in Swadkoh area of Mazandaran. In this regard, first, based on field observations and using satellite images, more than 319 old and new landslides were verified and identified. Then the factors affecting landslides including slope, direction of slope, lithology, land use, distance from road, distance from river, distance from fault, rainfall and earthquake were analyzed and determined by matching the date of occurrence of landslides with the time of rainfall. that rainfall has played a key role in the occurrence of more than 180 landslides in the region. In this research, the MARCOS model was used to prepare a landslide risk zoning map, which is one of the new multi-criteria decision-making methods, which uses GIS software to map the landslide risk of the region in five classes: very low, low, medium, A lot, a lot was prepared. The output of the model shows that more than 63% of the region is located in areas with moderate to high landslide risk, which are mainly at an altitude of less than 2000 meters, lands with a slope of 20 to 30 degrees, in the bed of rocks rich in clay minerals (Shemshak Formation, Seri Continental Formation, Same width as Qom Formation and Quaternary alluvial sediments) are 100 meters away from roads and rivers. Also, more than 146 villages are located in areas with moderate to high landslide risk, and the occurrence of 38 landslides in the context of villages and 137 landslides at a distance of 300 meters from the legal boundary of the villages indicates the high accuracy of the mentioned model; Validation of the model using the density ratio method showed that the accuracy of the Marcus model is 89.1%, which indicates the very good accuracy of the mentioned method, that the occurrence of 283 landslides in areas with medium to high risk shows a relatively good agreement between the results of this study and the experiences obtained from field observations. and geotechnical and geophysical studies conducted in the region. The results can be used in the preparation of city master plans, sustainable development plans of rural systems and rural leader plans to identify  rural habitations exposed to landslides or to identify the limits of physical development of  rural habitations.

Climatic and regional conditions have provided a good environment for agricultural development, especially in the Caspian Sea provinces. The purpose of this study is to identify the effect of climate variables on spatial analysis of grain yield and Grain cultivation capability in the southern coast of the Caspian Sea. Then, using important functions of spatial statistics including moron index and hot spots analysis of spatial patterns of rice, wheat and barley yields on the southern coast of the Caspian Sea during the statistical period of 2000-2016 were investigated. According to the results of Moran index analysis, it was determined that the yield of rice, wheat and barley were positive and close to one in the study period, indicating the clustering of the spatial distribution of the yield of the products under study. Also, based on the results of Local Indicators of Spatial Association and the analysis of hot spots, high value values or positive spatial correlation of rice yield were mainly found in Mazandaran province and high values or positive spatial correlation of wheat yield in southern parts of Golestan province and limited parts From Mazandaran Province. For yield of barley, the most areas with high positive spontaneous autocorrelation (hot spots) are mainly confined to Babolsar and Joybar cities of Mazandaran province at confidence level of 99%, Babol in 95% confidence level and Aliabad city Located in Golestan province at a confidence level of 90%. Low value of wheat and barley yields were found in the eastern and western parts of Gilan province at 99, 95 and 90 percent confidence levels.

Subtropical anticyclones are among the large-scale atmospheric centers of action in the northern hemisphere in the east of the oceans. Clockwise flow and high surface pressure are two prominent features of these systems. These systems have an annual trend and usually achieve maximum flow and surface pressure in the summer, especially in July. Understanding the factors influencing the development and intensification of these anticyclones has been the favorite of many researchers. One of these factors has been the general circulation of the atmosphere. In this study, a climatological study of the general atmospheric circulation, including the Hadley and Walker circulations, has been performed. Their role in the development and strengthening of subtropical anticyclones has been investigated. The research has been done in three parts; 1- Mean Meridian Circulation, 2- meridional circulation in the North Atlantic and Pacific, and 3- Walker circulation in the North Atlantic and Pacific. In this study, the meridional component of wind, vertical velocity (omega), and horizontal wind divergence have been used. Data at 27 pressure levels with a horizontal resolution of 0.25 × 0.25 ° were extracted from the European Center for Medium Weather Forecasting (ECMWF) and the ERA5 version. The monthly mean of the data used was conducted over 40 years, from 1979 to 2018. The Mass Stream Function (MSF) method has been used to quantify the meridional and walker circulation.The Mean Meridian Circulation showed that the meridional circulation in the equinox months consists of a pair of Hadley cells in which air rises in the tropics and subsides in the subtropics. Also, a solstitial cell is found with the ascent in the outer tropics of the summer hemisphere and subsidence in the outer tropics of the winter hemisphere. Although the Mean Meridional Circulation showed that mass transfer takes place in the summer of the Northern Hemisphere to the Southern Hemisphere and the Hadley circulation could not explain and justify the maximum activity of the subtropical anticyclones, but the meridional circulation at smaller cross-sections in the East Atlantic and Pacific showed that the Hadley cells play a vital role in mass transfer to the subtropics and mid-latitudes. The mean walker circulation (20-40 ° N) showed that the source of this circulation is only the latent heat released over the waters and the lands of the western oceans that have no role in mass transfer to the east. Westerly and southwesterly winds also form mass transfer in the Walker circulation to the northeast of the oceans. Heating in northwestern Africa and North America is another phenomenon that plays a role in subsidence in the North Atlantic and Pacific. The subsidence induced from heating on African lands is much more severe than that in North America. This may depend on the climate and extent of these areas. Therefore, as a result of this research, it can be said that three processes: Hadley circulation, Walker circulation, and heating on the lands adjacent to the eastern oceans, are effective in mass transfer and subsidence in the east Atlantic and Pacific. These conditions form strong northerly winds in the eastern oceans and trade winds in the tropics and effectively develop and strengthen subtropical anticyclones.

This study presents a climatological study of a subtropical anticyclone from North Africa to Iran, focusing on maximum counter-clockwise current. Atmospheric data with a horizontal resolution of 0.25 × 0.25 ° from the European Center for Medium Weather Forecasting (ECMWF) and the ERA5 version have been used. The monthly mean of the data used was conducted over 40 years, from 1979 to 2018. The results show three separate anticyclones in the middle atmospheric levels in Africa, Saudi Arabia, and Iran. These anticyclones have a seasonal evolution and reach their maximum intensity in the boreal summer. The maximum counter-clockwise flow in these systems occurred at approximately 650 to 500 hPa levels. High cells in the middle levels also correspond to the maximum counter-clockwise flow, and outside of these levels, the gradient of high cells in the pressure levels is reduced. Air subsidence occurs on the east side of the anticyclones and concentrates northeast of the center of the systems, and does not correspond to the high cells and ridges in the middle levels. Therefore, adiabatic heating due to air subsidence does not play a role in forming high cells and ridges, and their structure is due to the intense sensible heating of the surface and the lower levels in these areas.

Weather and climate hazards such as drought can seriously threaten natural ecosystems and human societies. The phenomenon of drought, due to its creep character and its non-sensible nature, affects the human environment more than any other hazards. In this study, daily rainfall data from a 26-year period was obtained for 16 stations in the mid-west of Iran from the website the Meteorological Organization of Iran. Then the drought periodic occurrences were calculated using the Standard Precipitation Index (SPI) in the periods of 1 month (monthly), 3 months (seasonal), 12 months (annual) and 24 months (long periods). To identify the daily and periodic atmospheric patterns of droughts, the dates that were as dry days were selected first. Using these dates, an array with 547 × 693 dimensions was prepared using geopotential heights data of 500 Hpa in MATLAB software. Maximum occurrence of drought occurred in the 12-month time scale and minimum frequency was in 1-month time scale of SPI. The reason for this is the most sensitivity of short-term SPI to humidity changes and the high contribution of monthly rainfall in changes of SPI. Most occurred droughts in the study area have mild to moderate nature. By increasing the time scale of the SPI, the number of dry spells and periods decreases, but their duration increases. Surveying the synoptic patterns showed that the patterns of ridge, zonal (in the daily patterns of the east-west stretch and the semi-longitudinal extension) and trough are the main patterns in the occurrence of the dry spells and periods in mid-west of Iran respectively.

In an agricultural system, crop production is related to climatic conditions. Therefore, a deeper understanding of the impact of regional climate change on production ensures global food security. Wheat is one of the most strategic crops and examining different aspects of its production is a necessity of every agricultural community. According to studies, wheat production is affected by various variables including environmental, individual and social, economic and technological. The aim of this study was to estimate the effect of these variables on changes in wheat production in different climates of Fars province. The required data were collected and analyzed through multi-stage random stratified sampling and 522 completed questionnaires through face-to-face interviews with farmers in the province. Farmerschr('39') attitudes were measured in the Likert scale and Cobb Douglas, Transcendental and Translog production functions were used to estimate the effect of variables. Results of comparing effective variables in three Cobb-Douglas, Transcendental and Translog functions; demonstrates the superiority of translog. From the perspective of the farmers of the province in the translog function, respectively; Soil moisture at planting time (0.692), effective rainfall during growing season (0.68) and at planting date (0.66), heat wave at harvest time (0.63), damaging rainfall (0.59) , Profit from wheat production (0.51), farmer education (0.49), soil quality (0.49) and cultivation method (0.49) with the coefficient of the mentioned criteria next to them; The most important factors explaining wheat production in Fars province. Independent variables in the translog function explain 92% of the changes in wheat production in Fars province.

Atmospheric Boundary Layer (ABL) is the lowest layer of the Troposphere affected by the land surface. Unlike the free atmosphere above, the land surface has a significant effect on the ABL and this layer, is the only part of the atmosphere that the effect of friction is seen and the diurnal variation of temperature is witnessed. In fact, the ABL plays the role of a dealer of energy and mass between the land surface and the free atmosphere. Many efforts have been undertaken to understand the behavior of the ABL due to its importance since almost all human activity (except aviation) forms in this layer. This, however, should be mentioned that those efforts are in a strong correlation with the development level of the country and the methods to study the ABL varies country by country. The study methods for ABL observations are divided into three main branches: a) Modeling and Simulation (using dynamic and numerical models); b) Numerical estimation (using atmospheric profiles); and c) Using High-tech devices (Remote Sensing, RADAR, and LiDAR).Like most climatology phenomena, the ABL probably owns some regular pattern in different time scales. In this research, the variation of the ABL over the city of Tehran is investigated in an annual time scale. The reason to choose the city is the high population, high urban concentration, and constant integration with inversion and air pollution, and above all, lack of knowledge about the ABL over the city.

In order to conduct a thorough research, long term data was required. Therefore, 30 years of data were gathered in daily time scale (at 00:00 GMT and 12:00 GMT equal to 03:30 and 15:30 Tehran Mean Time respectively). Total data records reached a sum of 10958 for each parameter. Data were collected from the European Center for Mid-range Weather Forecast (ECMWF) and the Atmospheric Science Department of the University of Wyoming. Data gathered from the ECMWF was in NetCDF format and the air profile gathered was in Notepad form.To have solid results, the data should be of high certainty and reliability. To investigate the reliability of the ECMWF data, the ABL height was calculated for some days employing the Advanced Parcel Method which defines the top of the ABL as the height in which the virtual potential temperature is equal to that of the surface values. Using Cochran's method to estimate the volume of the test subject from a society, 372 days were randomly selected and the ABL height was calculated based on radiosonde profiles. Then, the correlation coefficient and the Root Mean Square Error (RMSE) between the two data sets were calculated and since the coefficients were significant, data was used further. As for the maps, data gathered from the ECMWF was averaged using the ECMWF tools. This tool uses the R (or Rstudio) software and the RBridge to calculate integrated NetCDF data. The maps were drawn in ArcMap 10.

Mean daily ABL height was located almost at 850 meters above ground level (AGL). Of course in the average state of the highest elevation in the layer were occurred on the south and southwest of Tehran with a height of 873 meter and the lowest elevation were in the northwest of Tehran city with an altitude of 745 meter. While nighttime ABL descends to almost 80 meters AGL, the daytime ABL rises to 2300 meter AGL. The ABL height has experienced a total rise of 5 meters per day in the total time period of the research. Spatially, the lowest ABL heights were experienced in northeastern part of the city and the highest ABL were measured in south and southwestern part of the city. Also, the correlation between the mean daily data (the ECMWF uses eight data measurements to calculate the mean daily data) and the maximum and minimum averages were calculated. The results showed that the maximum values are of higher influence in mean daily data rather than the minimum.The findings also indicate that, during all 6 periods of the study time scale, the position of the minimum and maximum boundary layer values are almost the same. High values occur at south and southwest of the city and low values occur at northeast of the city. There is also a midsection area that is usually extended from Kan valley to the east of the city. There is also a sign of some core area, especially the one located above the Pardisan Park that sometimes affects the ABL patterns.Furthermore, the correlation between the ABL and some climatic parameters (e.g. sunshine hours, surface temperature, surface heat and moisture flux, relative humidity, air pressure, wind speed at 0, and 10 meter height AGL) was calculated. The results indicated that there is some significant correlation between the ABL and climatic parameters. The highest correlation was calculated between the ABL variation and the surface temperature. Seemingly, the closer the measured parameters to the surface are, the higher the correlation coefficient will be.

The Boundary layer height fluctuates between 80 meters AGL at nights to 2300 meters in daylight. The average height has increased almost five meters per year. However, since 1988 to 2012 it has risen and after 2012 it experienced subsidence. Both in minimum and maximum, the highest boundary layer height has been measured in south and southwestern part of the city and the lowest values were measured in northeastern of the city. The iso-height lines are extended from northwest to southeast. This is probably due to the effect of Alborz Mountain rang surrounding Tehran in northern edges. The ABL showed high correlation with some climatic parameters but the coefficient between the ABL height and some other parameters were insignificant. Apparently, the closer to the surface is the measured parameters, the higher the coefficient. Moreover, regarding the correlation coefficient and the root mean square error results, the Advanced Parcel Method seem to be of enough reliability to calculate the boundary layer height based on radiosonde profiles.

Introduction :

Atmospheric moisture resources which affect rainfall in a region are one of the most important issues in atmospheric sciences. In addition, understanding the mechanism of origin and transfer of atmospheric moisture causes the knowing of water cycle in a region. The main components of water cycle are the evaporation from land surface and oceans, transfer of water from ocean to land, precipitation over oceans and lands and the recurrence of water from land to the ocean. Consequently, the percentage of moisture flow of a region and amount of evaporated water could be evaluated using atmospheric moisture flow and observed precipitation. Therefore, the effect of evaporation from water bodies and transfer of atmospheric moisture on precipitation could be determined by calculating them. The spatio-temporal variations of precipitation could be investigated by study of moisture fluctuation due to variations in atmospheric circulation in dry and wet patterns conditions. Therefore in recent study the difference in atmospheric patterns of drought and wetness conditions, moisture flux and water resources which affect the transfer of moisture over Iran in various atmospheric levels.

 Materials and Methods:

In this study, re-analysis data of the ERA interim center of Europe medium-term forecasts (ECMWF). With a spatial resolution of 1 ° * 1 ° of geographical latitude and longitude for a 1981-2011 period were used. In order to find the wet and dry patterns in Iran, precipitation data were used. Moreover, geo-potential height, specific humidity, zonal and Meridional components of wind in 00 and 12 UTC of 1000, 850, 700, 500 and 300 hPa for analysis of atmospheric moisture source were used. Standardized Z-Index was used for determining dry and wet patterns over Iran and the percentage of occurrence of the patterns worked out yearly and the year with maximum percentage of area of occurrence of dry and wet periods were selected for further analysis. In next step, precipitation periods of selected years with precipitation of more than 1 mm and minimum 30 percent of affected area were determined for estimating contribution of water bodies in the periods. The total vertical divergence of moisture flux were calculated in 1 ° * 1 ° of geographical latitude and longitude networks in lower, middle and upper and total atmospheric thickness over Iran for selected years. In the next step, the positive and negative values of moisture flux of each network were derived for Iran and water bodies out of Iran, respectively. In the last step, atmospheric circular and specific humidity maps of precipitation periods of wet and dry years were prepared and analyzed for 850, 700 and 500 hPa as a indicator of lower, middle and upper levels, respectively.

 Results and Discussion:

The results of calculation of Z-Index showed that the 1995-96 and 1999-2000 were determined as wet and dry years with 87.3 and 98.7 percents, respectively. The humidity flux and percentage of variations for all layers were more in wet year as compared to the dry year. The most contribution in transfer of moisture in wet and dry periods was related to Arabian Sea over Iran. The Mediterranean and red seas were in the second order, Persian Gulf was in the third order, and black Oman and Caspian seas were in the next orders in both wet and dry periods. The Arabian and Caspian seas had no impact on moisture due to the flow patterns in middle atmospheric levels. Therefore, the Mediterranean Sea had the most contribution for transfer of moisture over Iran. In upper levels, the contribution of water resources in transferring the moisture was the same as the middle levels. Although, the amount of moisture flux was changed. The results also revealed that the southern border of the country are the most important direction for the entering moisture, especially at atmospheric lower levels. It might be due to the fact that the southern water bodies and Arabian Sea are the main moisture sources at atmospheric lower levels. In overall, the atmospheric low levels had a significant role in transferring moisture in Iran at all directions and the atmospheric upper levels had lesser task in this regard and the southern and western directions had more contribution as compared to other directions. 

Conclusion:

 The results showed that the flow pattern of the region and water bodies had a remarkable role for imported moisture variations over Iran. The moisture flux at wet period was more at all levels in wet year. In addition, Arabian Sea at atmospheric low level and Mediterranean Sea at medium and upper levels had more contribution for transferring moisture content in Iran. Moreover, the results showed that southern border were in first priority and western borders in second priority for importing moisture at atmospheric lower, medium and upper levels over Iran.

Precipitation, as one of the most important elements of the hydrological cycle, is affected by climate change and this can lead to new conditions in water resources.In the present study, to monitor and simulation of Precipitation conditions in the southern coast of the Caspian Sea (Gilan and Mazandaran provinces), daily precipitation data of Astara, Rasht, Bandar Anzali, Ramsar, Gharakhil, Noshahr and Babolsar synoptic stations for base period 1986- 2015 from the Meteorological Organization and daily data for CanECM2 model with three scenarios RCP2.6, RCP4.5 and RCP8.5 from the Canadian Climatological Site was obtained. SDSM version 3.5 was used to simulate precipitation changes over the future period (2021-2050). After doing model calibration and validation, the downscaling of precipitation data was performed for the future period (2021-2050). Then, intensity, duration and frequency extreme indices of precipitation for the base and future periods were calculated. The results of three scenarios showed that the average annual precipitation in the study area increased, on average, by 20 to 70 mm as compared to base period (1986-2015). In addition, the results of analysis of precipitation indices showed an increase of precipitation with more than one mm in all weather stations and an increase of precipitation with more than 10 mm in most of the weather stations, excluding Babolsar and Gharakhil, in the future period 2021-2050 in comparison with the base period. However, the precipitation more than 20 mm was similar in the future and base period with a little change. The results revealed that a decrease in R95p and R99p indices at Ramsar and Nowshahr stations and an increase in the western and eastern parts will occurred in the future. Moreover, a decrease in the dry period length will happened in the future as compared to the base period. The extreme precipitation values are expected to be high for the region, which will increase the average annual precipitation.

Introduction Understanding of climate parameters and their effects on crop growth is one of the most important agricultural issues. The purpose of this recognition is to increase crop yield and thereby increase production. The position of Iran and its natural geographic features have led to a variety of climate and seasonal variations. These variations in each season has created different conditions for agricultural products. Among the climatic elements, the amount and temporal distribution of rainfall and temperature fluctuations in different stages of crop growth have the greatest impact on the yield of agricultural products, especially rain-fed wheat cultivation. In the growth stages of each crop, especially in rain-fed agriculture, the planting date and the first effective rainfall are an important environmental-managerial factor in production. The main goal of current study was to investigate the relationship of synoptic patterns of effective precipitation with planting date and yield of rain-fed wheat in Kermanshah County. Materials and Methods In this study, data from growth stages (phenology) of wheat, Azar-2 variety, and precipitation of the agrometeorological research station of Sararood, Kermanshah were used from 2004-2005 to 20015-2016. In the next step, the data of geopotential heights, wind speed and direction and specific humidity from 850 and 500 hPa levels were taken from NCEP / NCAR reanalysis dataset. The planting date of rain-fed wheat has been calculated based on 2 methods. In the first method, the starting dates for the first effective rainfall were determined. Accordingly, the date of cultivation was when the total precipitation of 5 mm within one or two consecutive days occurred and after that, the precipitation occurred by 10 days. The second method was to determine the planting date on the basis of climatic data of sowing and germination dates recorded in Sararood agrometeorological research station during the years of study. The effective rainfall was defined as 5 mm rain to wet 5 cm of soil depth for a soil with loamy. Moreover, the staring date of sowing wheat was calculated according to Weibull formula with a 75-percent probability of success. In the following, taking into account the first days of precipitation and based on the number of rainy days, the synoptic patterns of the occurrence of effective rainfall have been derived using a correlation-based method. Results and Discussion According to the results, suitable dates for Rain-fed wheat cultivation in Kermanshah Province were from Aban 3(October 25) to Aban 15 (November 5). In this research, by determining the threshold of correlation coefficient (0.57), 4 general synoptic patterns were found. The features of each pattern were as follows: pattern 1 had the highest share in severe rainfall. This pattern in the pre-germination stage (sowing) had the highest frequency in the occurrence of effective rainfall of 5 mm and more. Pattern 2 was in contrast with Pattern 1, and it was most frequent occurrence in rainfall. Patterns 3 and 4 had characteristics such as limited rainy days and extreme daily rainfall. In addition, synoptic patterns of effective precipitation more than 5 mm were minor trough, Mediterranean trough, Omega Block and cut-off low. The results of synoptic studies of atmospheric patterns also showed that the northern seas of Indian Ocean (Red and Arabian Seas) are the main sources of moisture for all synoptic patterns. Conclusion The main goal of current study was to investigate the relationship of synoptic patterns of effective precipitation with planting date and yield of rain-fed wheat in Kermanshah County. The effective precipitation from synoptic patterns 2, 3 and 4 provided conducive conditions for germination of plant in the next priority after the first pattern. The results indicated that the lowest wheat yield as compared to average yield (2113 kilograms per hectare) occurred in the years with the forth precipitation pattern. On the other hand, the highest wheat yield observed when the synoptic patterns of 2nd and 3rd were occurred simultaneously within a year. For example, the years of 2006-2007, 2014-2015 and 2015-2016 had wheat yield of 2888, 2486 and 2700 kilograms per hectare, respectively. Moreover, the effect of synoptic patterns on planting date showed that the commencement of first effective rainfall with patterns 1, 2, 3 and 4 delayed germination stage with an average of 4, 10, 3 and 5 days, respectively. In conclusion, it should be noted that to take more precise results, it is reasonable to work with long- period data.

Now days ,in order to providing the best mecanisms to damp the impact of climate change , climatology scientists need long term prediction of climatical variables and their changes. This research studies the impacts of climate changes on daily parameters such as: rainfall , min and max temperature and sunshine hours in Urmia lake basin. (Tabriz ,saqqez and Urmia synoptic stations) , selected as study stations , have long term gaged data for mitigation and Adabtation from 1980 to 2009. data prediction under as scenario A2 a type of GCM as HADCM3 model was used to simulate climatic parameters in 2011 to 2040 by LARS-WG model downscaled. Results show that prediction time distribution has been limited to short time in comparison to past decades .In other words the number fraindy days has been diminished , as far as in the future April will have the most decrease (7.5%) and February will have the increase (5.8%) in precipitation . overall , the precipitation max and min averay temperature of basin will increase about (4.3%) , (1.35 ) and (0.64 ) respectively in addition, November will have the most increase in daily max temperature (12.7) and January will have the least increase (0.33) in this parameter the sunshine hours of basin will not increase significantly .

General circulation models (GCMs) are an important tool in the assessment of climate change. These numerical coupled models represent various earth systems including the atmosphere, oceans, land surface and sea-ice and offer considerable potential for the study of climate change and variability. However, they remain relatively coarse in resolution and are unable to resolve significant subgrid scale features such as topography, clouds and land use. Bridging the gap between the resolution of climate models and regional and local scale processes represents a considerable problem for the impact assessment of climate change. Thus, considerable effort in the climate community has focussed on the development of techniques to bridge the gap, known as ‘downscaling’. In this study two statistical downscaling techniques (lars WG and SDSM) and Proportional Downscaling method have been sued , which are combination to TOPSIS approach.The result shows SDSM is more ability technique of downscaling. And climate change will reduce monthly rainfalls up to 39% and increase the temperatures up to 2 °C.

Introduction Soil temperature and its variations over time and space is one of the most important factors which not only affect matter and energy exchanges in soil, but rate and direction of all physical processes, directly or indirectly are related to soil temperature. This parameter is a significant factor in agro-meteorology which most of the time is more important than air temperature for plants, from environmental point of view. Soil Temperature assessment at different depths requires knowledge of its physical characteristics such as thermal conductivity, soil specific heat capacity, diffusion coefficient and etc. when these parameters are not available, it’s impossible to access the temperature vertical distribution in soil profile and needs to use simple methods. Statistical and empirical methods which are able to show acceptable results in soil temperature assessment can be a proper way to calculate this parameter in location without soil temperature measurements. So, regarding to importance of soil depths temperature calculation in agriculture, engineering and etc., the main objective of this study is determining a numerical model for estimating soil depths temperature. 2-Methodology In this study, soil depths temperature variations pattern were determined based on measured data, firstly. Then, performance of an empirical model for estimating the soil depths temperature was tested. To do so, monthly and annual temperatures of 5, 10, 20, 30, 50 and 100 cm of soil in Mehrabad synoptic station at 3 times in a day during the 2008 (6:30, 12:30, 18:30 at local time) were extracted from Iran Meteorological Organization and temperature pattern of each depth was studied. For calculating temperature in different depths, temperature of 5cm was used as base temperature and temperature of other depths was estimated by using sinusoidal equation. For calibrating the estimated and measured temperatures, statistical methods such as correlation coefficient and Nash-Sutcliffe efficiency coefficient were applied. 3-Disscusion According to the results soil temperature indicates similar monthly pattern in all depths, so that maximum and minimum temperature is related to July-August and January-February-December, respectively. Also, Hourly soil depths temperature illustrated that in near surface depths (5cm) maximum temperature occurs in middle of the day (12:30), while minimum temperature is recorded after sunrise (6:30). At the depth of 10cm, maximum temperature occurs at 18:30 because of a time lag in temperature transfer from surface to depth. Generally, temperature behavior of different depths demonstrated 2 distinct patterns during the year; in warm period, temperature decreases from top to depth, so that maximum and minimum temperature was recorded at 5 and 100 cm, respectively. But in cold season, trend of temperature variations is completely visa versa and temperature increases with depth. In addition, reconstructed soil temperature data display that there is a negligible difference between estimated and recorded temperature data, especially at the depths which are near the base surface (5cm), so that correlation coefficient between these two parameters varies from 0.99 at the depth of 10cm and 0.89 at the depth of 100cm and is significant at 99% level. Moreover, result of Nash-Sutcliffe efficiency coefficient varies from 0.9963 to 0.9114 which shows high efficiency of the empirical model. 4-conclusion The main objective of this study is analyzing an empirical model for estimating the soil depths temperature in regions which are not under cover of synoptic stations. Generally, results demonstrated that there is significant correlation between estimated and recorded data. Also, Calibration of the correlation and Nash-Sutcliffe coefficients showed that empirical equation has proper efficiency for calculating soil depths temperature.

Obtaining and Production of accurate and realistic information from mineral resources is one of the intellectual concerns of managers. To produce this kind of data and information, there are various methods that can be traditional methods combined with the field data and remote sensing techniques. Measurement and generation data using of satellite data and remote sensing methods especially, in desert areas because existing unfavorable conditions, opened up a new horizon to the managers to overcome the problems of traditional conventional methods.The purpose of this paper evaluate remote sensing and GIS techniques is to map evaporate minerals in the eastern part of Semnan using ASTER data.We used field data and false color, PCA and Tasseled cap transformation, ratio and data fusion techniques to estimate amount of gypsum, salt, sodium and magnesium sulfate soils. Regression and correlation relationships between satellite and field data were determined. The results showed that the thermal bands 9, 10, 12 and PCA 9, 10 and 12 can be used for separating Gypsum, Halite as well as sulfate. Finally using maximum likelihood classification map was used to map Gypsum, halite and sulfate contents with accuracy of 73.33, 66.67, 66.67% also using Kappa coefficient were prepared respectively, 0.61, 0.53 and 0.55.

Sand transport by erodible winds is one of the most important wind processes in arid and semi-arid regions. In this study، in order to determine the wind regime، different indices of same wind aspect index (UD)، sand transport potential index (DP)، erodible winds direction resultant index (RDD)، transport potential resultant index (RDP) were studied and compared with sand dunes morphology index in Semnan Plain. Garmsar، Semnan، Damghan and Biarjomand synoptic stations anemometer data and sand rose graph software were used to analyze wind data، sand transportation potential and sand rose drawing. Results showed that wind sand transportation potential is relatively high at all studied stations and more than 3000 vector unit (VU) throughout the year، according to six m/s threshold velocity which presents highly potential of wind erosion and sand transportation in the region. Annual (UD index is more than 0. 9 in Damghan station and varies between 0. 3 to 0. 8 in other stations. RDD index is also reflecting wind direction changes from 130 to 180 degree. These two indices are representing barchan sand dunes، barchanoid and or silk shape longitudinal dunes in Semnan_Garmsar plain that are formed along north-northwest to south-southeast winds. This condition show the close adaptation with Alborz mountains cold and high pressure condition at the north part of the region and southern situation of Gramsar، Damghan and Semnan plain and also with topography pathway of the region. Sand dunes moving index shows that they are moving and their current vegetal coverage is the result of de-desertification activities.

Materials and surfaces with different thermo-physical properties provide variety of temperature patterns and temporal changes. Analyzing thermal behavior of the different land covers is one of the significant factors to determine urban microclimates. Urban land covers have usually high temperature. This can potentially increase the intensity of urban heat island effect and building cooling energy consumption and also change energy balance and heat fluxes in these areas. Therefore, regarding to the impact of surface temperature on changes of surrounding air components and formation of Urban Heat Islands (UHI), the main objectives of this study are including identification of the circadian pattern of surface temperature in different weather conditions and providing the best regression model to estimate surface temperature using air temperature. To determine the surface temperature patterns of different land covers such as Asphalt, Soil, Cement and Stone, three data loggers along with four Platinum Resistance Thermometers (PT100 sensors) were installed in Geophysic Weather Station in University of Tehran. Therefore, temperature of these land covers was recorded hourly during the November 2012. Furthermore, meteorological data including air temperature (°C), relative humidity (%), precipitation (MM), and cloudiness (Okta) were gathered from Geophysic Weather Station. Then, circadian temperature pattern of different land covers were selected to be analyzed in six days of November with different weather conditions (Sunny, Cloudy, Rainy conditions). Finally, the best regression model for predicting daily mean surface temperature was provided using air temperature. In addition, two statistical methods such as Nash-Sutcliffe efficiency coefficient and correlation coefficient were used for determining the efficiency of the regression model in estimating the different land covers surface temperature. According to the results, it can be concluded that in sunny and cloudy conditions surface temperature of all land covers increase with sunrise at 6 A.M. (local time) and this trend continue until noon so that, maximum surface temperature occur around 12 P.M. Then, surface temperature decreases because of reducing the amount of solar radiation and finally at sunset, the surfaces lose their heat, obtained during the day, as long wave radiation. It is important to note that in cloudy conditions, the amount of energy absorption during the day and it loses during the night is less than sunny conditions because of cloud cover existence in the sky and the effect of the cloud’s albedo. Therefore, in these weather conditions surface temperature pattern has sinusoidal mode but temperature range (difference between maximum and minimum temperature) on cloudy conditions is less than sunny conditions due to cloud cover so that studying relationship between surface temperature and cloudiness depicted that there is inverse relationship between them and temperature reduces when cloudiness increase. It was also illustrated that there is no specific hourly trend in surface temperature in rainy conditions and there are many variations in surface temperature. Totally, on sunny and cloudy conditions the highest temperature is related to Asphalt, Cement, soil and Stone, in order. While on rainy conditions Asphalt has the lowest temperature between the studied land covers because of water flow over the surface. Thus, it can also be concluded that permeability of the surfaces is one of the most significant physical properties in the surface temperature behavior. Land covers which are impermeable (such as Asphalt, Cement and Stone) in rainy conditions show lower temperature because of the water impact. In addition, reconstructed surface temperature data display that there is a significant correlation between observed and estimated temperature using daily mean air temperature, so that correlation coefficient between these two parameters varies from 0.98 to 0.97 and is significant at 0.01% level. Moreover, result of Nash-Sutcliffe efficiency coefficient varies from 0.8232 to 0.9205 which shows proper efficiency of the regression model. The main objective of this study is analyzing surface temperature of different land covers during the day/night and different weather conditions and also providing a regression model for estimating the surface temperature in these land covers. Generally, this can be concluded that different land covers surface temperature is completely a function of their thermal properties in calm and sunny weather conditions. Some surfaces such as Asphalt and cement which have less thermal conductivity and high absorbency show the highest surface temperature during the day. While, on rainy conditions both air and surface temperature have many variation because of cloudiness and precipitation. In such conditions some physical properties like permeability of the surfaces play significant role in thermal behavior of land covers. Finally, according to the correlation and Nash-Sutcliffe coefficients it is concluded that regression coefficients between daily mean air temperature and surface temperature have proper efficiency for calculating daily mean surface temperature.

Different material’s thermo-physical properties have significant impact on near-surface weather condition which leads to the formation of the urban micro-climates so that، these properties are the main reason for difference between urban and rural air temperatures. To extract different land cover surface temperature patterns such as Asphalt، Soil، Cement and Stone، three OPUS 200/300 Data Loggers with six PT100 sensors were installed in Geophysic Weather Station in University of Tehran and the temperatures of land covers were measured in 10 minute-time intervals during one statistical period (2012-2013). Then، using weather condition data gathered from Geophysic weather Station، land covers surface temperature patterns were divided into six categories including Sunny، Rainy، Snowy، cloudy، windy and a day after rain. Generally، one can conclude that different land covers surface temperature completely obey their thermal properties in sunny، windy and cloudy weather conditions so that، some surfaces such as Asphalt and cement which have less thermal conductivity and high absorbency show the highest surface temperature during the day but only there are some fluctuations in temperature behavior in cloudy and windy conditions which are according to the cloud cover changes or wind speed. While، in rainy and snowy conditions both air and surface temperature have many variations because of cloudiness and precipitation، and the trend of temperature is not sinusoidal and the main factor is permeability; for example some surfaces such as soil with high permeability shows high temperature.

Introduction In some regions, particularly the Middle East, the dust storms occur with high frequency. Since the past decade, the occurrence of dust storms has increased in this region (Kutiel & Furman, 2003: 419). Several factors are involved in the creation of the dust storms, but the main factors are circulation of the atmosphere and earth surface. Synoptic studies have shown that low and high pressure (especially dynamic), and the vertical motion of air are the main causes of dust storms in the Middle East (Omidvar, 2006; Lashkari, et.al., 2008; Mehrshahi, 2009; Tavousi, 2010). Daily mean of dust storms in Iran, especially Khuzestan in the warm season is more than other seasons, and the highest frequency has been observed in the Zabol (Raeespour, 2010; Farajzadeh, 2011). The frequency of these storms will be increased after droughts, because the ground is dry and has less vegetation (Miri, et.al., 2009). To investigate the mechanism of dust storms in Middle East, dust storm occurrence in first days of July 2009, that is the biggest storms, has been elected, in this study interaction between atmospheric circulation and earth surface properties including soil moisture, land cover and soil type has been studied by a synoptic approach. Methodology Dust storm classified based on the origin. The Storm of Syrian origin, has been selected for this study. The Satellite images and Synoptic maps showed that period of this storm is 30 June to 9 July and south of Syria, Iraq and Iran influenced by dust storm. In this research, several types of data are used including zonal and Meridian wind, Geopotential height, Omega, Precipitation, sea level pressure, soil moisture from NCEP, Land use from RegCM/3 Model and satellite images (MODIS). The method of the research is the synoptic approach. Results and Discussion This dust storms caused by the development of Persian Gulf low pressure and extension of a trough to south of Turkey that create cyclonic circulation in the surface of southeastern Syria. These mentioned Conditions and also wind speed increasing in surface, low level of troposphere with location of the trough in the middle and upper level of the troposphere alongside dry and Gypsiferous soil have effects in the creation of dust storm. After creation of the dust storm by surface and low level instability over desert of Syria on the 1 July, then it spread over Iraq due to the development and extension of instability caused by the trough in middle and upper level and northwest wind. Through shifting to the east and changing the wind direction and also more important instability through troposphere, dust storm on the 4 July passed from Zagros Mountains and spread over Iran. In the next days, dust storms moved to east and northeast and influenced almost of Iran. This condition Remained to July 9 over Iran. Conclusion Maximum radiation and minimum precipitation in warm season caused the negligible soil moisture in this region by. The soil of dust storm area, except a very small of margin River in southern Syria and northwest of Iraq is soft, fine grain, Gypsiferous, and without any cover. Middle East at the warm season is dominated by subtropical high pressure and subtropical jets stream, but the circulation of the atmosphere during dust storm, shows that a low pressure extends over Persian Gulf and south of turkey. This condition causes the formation of cyclonic circulation in the East of Syria on 1 July. Wind speed Increasing, cyclonic circulation, dry soil and lack of coverage, provided the conditions for removing the soil particles. Due to the extended ground surface's low pressure and instability of low level of troposphere, dust storm enhances and moves to south-southeast over Iraq and Persian Gulf. But unstable layer is shallow, and then storm has not passed from the heights of West Iran. Dust storm passed from Zagros Mountains and entered to Iran due to moving trough from west to east of Iran and development of instability on July 4. In the next day (5 July) a cyclonic circulation has been created in central Iran, this circulation and extended instability caused the spread of dust over almost of Iran exactly southeastern regions. This study shows that both of atmospheric circulation and condition of ground surface are important in creation of dust storm in the Middle East.

In this article, an attempt was made to study the Iran’s trend of temperature in recent decades, dealing with the relationship between this trend and increase in the amount of co2 in the atmosphere. First, stations with long-term data (since 1958: because data about co2 was available since 1958) were selected, then those which missed data in two successive years, were deleted from the dataset and all the study was conducted just with 12 stations. In this research, in order to determine the authenticity of the data, autocorrelation test and run test were carried out and nonparametric Mann Kendall test was performed to determine its amount, direction and significance. According to the results obtained, in the most stations under consideration (synoptic stations) the increasing of temperature with different rates was observed, for example Abadan and Shahrood were not observed trend, Esfahan, Tabriz and Kerman slight positive trend, Babolsar and Zanjan moderate positive trend, Yazd, Kermanshah and Mashhad some high deal trend, Tehran and Boushehr high trend and Anzali moderate negative trend observed. It was supposed that there is a same relationship between the trend of increasing temperature in Iran and the growth in the amount of co2 in the atmosphere.