mohammad saligheh

The spatial distribution and trends of cloudy days, particularly during the cold season, carry significant importance for environmental planning and water resource management in arid and semi-arid regions. Clouds, as a crucial component of the hydrological cycle, play a vital role in regulating precipitation patterns, temperature, and evapotranspiration. This research aims to investigate the trends in cloud cover during the winter season and identify the influencing factors in southeastern Iran. By utilizing data from 23 synoptic stations and reanalysis data from the European Centre for Medium-Range Weather Forecasts (ERA5) covering the period from 1989 to 2022, this study employed statistical analyses, including the spatiotemporal distribution of low-level cloud cover (LCC), the Mann-Kendall trend test, and linear regression modeling, to assess long-term changes. The results indicate that the spatial distribution of cloud cover in the study area is influenced by geographical factors such as latitude, longitude, altitude, and atmospheric patterns. Furthermore, trend analysis using the Mann-Kendall test and regression on both observational and ERA5 reanalysis data reveals a decreasing trend in cloud cover during the months of December, January, and February. The most significant decrease in cloudiness was observed in December. The findings of this research can enhance our understanding of regional climate change and improve climate prediction models. Moreover, the results can contribute to water resource management, as well as agricultural and energy-related planning in southeastern Iran

Mineral Dust, the most important type of aerosol, has a significant direct and indirect role in weather and climate. In this case, it intend to investigate the capability and capability of MACC model validated by MODIS for detection of dust episodes in the Kurdistan province during 2003-2012. To achieve that, we analysis satellite and model data using Man-Kendall trend and statistical tests. The results of the temporal distribution indicated that the mean Aerosol Optical depth (AOD) in 2008 was 0.36 and its lowest was 29.04 for 2004. In addition, average AOD in menthioned year was 0.036, 0.335, 0.385, 0.377 and 0.3368 for the cities of Sanandaj, Saqez, Ghorveh, Kamyaran, Marivan, respectively. The spatial distribution of AOD average in different seasons showed that winter and autumn had the lowest amount and spring, and summer season had the highest AOD. AOD's monthly spatial distribution showed that high dust belonging to April-August period to covers completely interested area.The results of the Man-Kendall test showed that the area had a significant positive trend in the spring season throughout the province and the summer season in the east of the province. Therefore, the spring season in the area known Extreme Season and June 19, 2009 between the five days of the dust extreme is as an extreme episode with an average AOD of 1.16 and a horizontal visibility of less than two kilometers that it have the highest and most widespread mineral dust. In general, the results of the MACC with multidimensional approach showed that optical depth (AOD, DOD) is a more appropriate criterion than horizontal visibility in determining dust storm.

One of the patterns of major climate changes in tropical maritime regions is the Maden-Julian oscillation, which affects sub-seasonal time periods of 30 to 60 days, tropical and subtropical regions. This phenomenon brings the variability of various quantities of the atmosphere and the ocean, such as pressure, surface temperature, and the rate of evaporation from the ocean surface in tropical regions. In this research, first, the daily rainfall data of 48 synoptic stations, 1980-2020, was obtained from the Meteorological Organization. And quality control in three zero levels 1 and 2, including structural quality control, physical limits, correlation of parameters within the report, climatic range, temporal and spatial correlation, quality control.The Madden-Julian Oscillation is one of the large-scale climate change patterns in the maritime tropics, with subseasonal time periods of 30 to 60 days affecting tropical and subtropical regions. This phenomenon can cause changes in various quantities of the atmosphere and ocean, such as pressure, sea surface temperature, and the rate of evaporation from the ocean surface in tropical regions.In this research, the effects of Maden Julian fluctuation on the weather elements of Iran have been investigated with the aim of knowing the effects of different phases in order to improve the quality of forecasts and benefits in territorial planning. At first, the daily rainfall data of 1980-2020 was received from the National Meteorological Organization and quality controlled. Using the Wheeler and Hendon method, the two main components RMM1 and RMM2 were analyzed, based on which the amplitude of the above two components is considered as the main indicator of the intensity and weakness of this fluctuation. This index is based on the experimental orthogonal functions of the meteorological fields, including the average wind levels of 850 and 200 hectopascals and outgoing long wave radiation (OLR) between the latitudes of 20 degrees south and 20 degrees north. The clustering of the 7-day sequence with a component above 1 was used as the basis for clustering all eight phases, and by calculating the abnormality of each phase compared to its long term in the DJF time frame, the zoning of each phase was produced separately. In the end, phases 1, 2, 7, 8 were concluded as effective phases in Iran's rainfall and phases 3, 4, 5, 6 as suppressive phases of Iran's rainfall.Phases with a sequence of 7 days and a component above 1 were used as the basis for clustering all eight phases, and by calculating the abnormality of each phase compared to its long duration in the DJF time frame and by passing the data through the 30-60 day intermediate filter, zoning Each phase was produced in latitude 25 to 40 degrees north and longitude 44 to 63 east. With the investigations carried out and the output of the models and finally the production of zoning related to Iran's rainfall anomalies in the eight phases of the MJO, the country's daily rainfall data were analyzed in the period from 1980 to 2021, which finally after applying Data optimization filters, Iran's precipitation zoning output using Arc Gis software were produced separately for all eight phases. According to the outputs, the distribution of rainfall in the conditions of phase one can be seen with a variety of fluctuations, among which the share of rainfall and rainfall anomalies is greater in the southwestern and southern regions of Iran, especially in the regions of Fars, Hormozgan, West Kerman and Bushehr provinces. It is significantly different from other regions of Iran. In the region of the Caspian coast, the main reason for the rainfall is different from the rainfall in other regions of Iran, and it is not discussed in this analysis. Iran's rainfall anomaly in phase 2 has weakened compared to phase 1 of rainfall, and it can be felt that the anomaly is weaker in most areas. Iran's rainfall anomaly in Phase 3 of Madden Julian Oscillation has shown, we have significantly limited rainfall and almost locally. In phase 3, there is no rainfall in Iran, and obviously, with the beginning of the positive phase of the Madden Julian Oscillation, which includes phases 3, 4, 5, and 6, the changes in precipitation in Iran are different from the negative phases 1, 2, 7, and 8, and their changes can be considered in relation to each other.Eliminating the boundary between spatial-temporal scales and a deeper understanding of distant planetary systems is always an important challenge that the scientific community is facing. Undoubtedly, progress in medium-range and seasonal weather forecasting and our understanding of large-scale weather patterns and the identification of specific causes of their occurrence rely on our deep understanding of the behavior of atmospheric-oceanic patterns and their relationship with each other. to be Based on the direction of this research, the investigation of precipitation anomalies associated with the eight phases of MJO during the period of December, January and February 1980 to 2020 showed that the precipitation behavior of each of these phases is different from each other and the position, intensity and extent under the influence These abnormalities are variable in each phase.

in this research, their effects on the flight of airplanes were investigated. The study area is the country of Iran, and the flight routes of Kermanshah, Ahvaz and BandarAbbas to Tehran. The research data includes maps of the Vertical Transect (profile) of the jet stream, the daily average of the Zonal wind (U-Wind) and meridional wind (V-Wind) components for the winter period of 2018 through NOAA/NCEP environmental databases. Also, flight route information was received from FlightRadar24 and Flightaware systems. First, by using Vertical Transect maps, the days containing strong U-Wind were extracted, and the average position of the core of the Jet Streams in the Zonal and meridional wind components, the Tropospheric level of 200 HP was detected. The list of flights was prepared, and the Zonal Wind maps were produced. Finally, the height of the flights was compared with the level of the currents of the Jet Streams, and the influence or lack of influence of the Jet Streams on the flights was studied. According to the results of the research, all the Jet Streams caused turbulence for all flights, and they caused a decrease in the speed of flights between Ahvaz and BandarAbbas to Tehran and an increase in the speed of flights between Kermanshah and Tehran according to the direction and type of Jet Streams. It was also found that all the Jet Streams had a speed of more than 90 knots, so the capacity to create tension and turbulence such as CAT was seen in them

In this research, the changes in Iran's drought were studied using the rainfall data of 100 synoptic stations and the Standard Precipitation Index (SPI) for the period from 1990 to 2020. Then, the atmospheric pattern affecting the occurrence of droughts was synoptic analyzed. The results showed that the number of years with drought and its severity in the country increased during the study period. The intensity and spatial extent of drought in the winter season has increased more than in the autumn season. In the 1990s, the extent of drought was greater than drought. With the beginning of the second decade (2000-2010), the intensity and spatial extent of drought and the number of droughts have increased. This trend has continued until 2016, so that the country's most severe droughts have occurred in the last decade. The increase in the extent of drought in the winter season (January and March) is more evident during the last decade. These conditions were caused by climate changes and variations in the behavior of circulation patterns. Also, the most severe droughts in the country occur in the cold period of the year,when the subtropical high pressure (STHP) extends to 30 degrees north latitude. In this case, the conditions of stability prevail due to the absence of conditions for the ascent and passage of rain waves. In general, droughts in the country have increased during the studied period, and the spatial extent of droughts is influenced by the location of the STHP.

Climate is one of the most important factors in enhancing combat capability in military units. The purpose of this study is spatial analysis of climate hazards affecting military activities in the southern half of the country. For the study, data from 55 synoptic stations with a statistical period of 22 years were used. Dust storms, heat stress, heavy rainfall and sultry conditions were identified as the most important climate hazards affecting military activities in the study area. The frequency of days with dust storm in the north of Sistan and Baluchestan province and in Zabol and Zahak stations is the highest and in terms of temporal behavior, in late spring and summer has the highest frequency of occurrence. The highest frequency of heavy rainfall in the study area was in autumn and winter. Summer is almost the whole region with heat stress. In summer and spring, the highest frequency of sultry intensity has occurred in coastal stations. From the combination of fuzzy maps in GIS software, climate hazard maps were extracted seasonally and annually. In spring and summer in northern Sistan and Baluchestan province and in autumn coastal stations were recognized as the most unfavorable place and winter as the best time for military activities in the southern half of Iran. Khuzestan province, which has a high frequency of heat stress, sultry intensity and heavy rainfall at the same time, is the most undesirable place for the establishment of military units on an annual basis.

In recent years, dust has been Iran's most important environmental crisis. On 25 February 1396, there was heavy dust in Iran which was important for research in two aspects: spatial extent and time of occurrence (winter). The purpose of this research is to analyze the synoptic conditions and to trace the phenomenon. For this purpose, satellite and re-analyzed data were used. Modis data showed that more than 60 percent of Iran's area to this day was affected by dusty airwaves, indicating that this phenomenon is widespread. The maximum optical depth of aerospace was observed in the northeast of Yazd province with a mean of 2.03. The results of the synoptic analysis of this phenomenon showed that at sea level a low-lying core comprises northeast and central parts of Iran. At a level of 850 hPa, a low altitude north of Lake Baikal and a high altitude over southern Pakistan and their resulting cyclonic and anticyclonic movements have led to the convergence of airflow in central Iran. The thermal contrast caused by the cold air of the upper latitudes and the warm air of the lower latitudes have resulted in the formation of a core of the hornbeam at a level of 500 hPa in central Iran. Minimum moisture content in all levels as well as rising air (based on equilibrium values) have provided the conditions for the rise of sweeping dust in Iran. Analysis of air mass routing 48 hours before the dust peak in three parts of southwest, central and northeast of Iran showed that air mass transfer route was in all parts of western Iran. However, even in the center of Iran, even at a height of 500 meters, the air mass has shifted from the Arabian deserts to Iran, resulting in heavy winter dust transfer to central Iran.

The smallest change in energy exchange of Earth System Shifts the balance of life. In order to be aware of the solar radiation Balance, Recognition of the measure of Balance level of the input and output components of radiation of input Short wavelength to the surface of the earth and Long Output Wavelength, it is necessary from the earth. To study the energy balance of input and output in Iranian plateau, the input and output radiation data of NCEP / NCAR site was used With a resolution of 2.5 * 2.5 *, including 46 cells in Iran,. For each season, a representative month was considered And correlation, confidence level, coefficient of determination and amount of oscillation of input and output radiation were calculated in different regions of Iran. Finally, some calculations were presented spatially with the IDW method. The results showed that the maximum short-wave wavelength was 230 watts per square meter in August and the lowest was 52 watts per square meter in November. The highest long-wavelength output in August was 65 watts per square meter, and the lowest amount was January and November with 20 watts per square meter. The highest the amount of output increase has been occurred in August in the east of province South Khorasan with a correlation of 0.59 to 112 watts per square meter in 2001. In decreasing output changes, except for May, there was a decrease in the rest of the months. The highest long-wavelength output was in the northwest and in the provinces of Ardabil and Guilan.

With the increase of urban constructions and land use change, especially in big cities, the temperature of urban centers has increased compared to the suburbs, which has led to the formation of the phenomenon of heat islands in these areas. In fact, the heat islands of cities are closed isthmus lines that are known as the heat centers of the city, especially in areas built by humans and artificial structures. Since the purpose of climate studies in urban plans is to identify the environmental characteristics affected by the prevailing climatic conditions, so it can be of great help in optimizing the spatial structures. Climatic factors and elements in their quantitative and qualitative changes affect the environmental situation. Although these changes may be gradual and gradual, they can have lasting consequences. Therefore, the study of heat islands due to urban settlements has been considered by most researchers and its consequences for urban planning and global warming over the past decade have been considered with the expansion of urbanization and the occurrence of urban-related phenomena. The study of urban heat islands has begun in most of the most populous regions of the world.

In order to develop the present study, the OK numerical equation has been used. Due to the fact that numerical models can be programmed in the field of climate by certain conditions, so they use micro-climate scales in applications. Therefore, in recent decades, under the developed conditions of cities, numerical models have been widely used, among these models is the Oke numerical model, which compares the results of the observed data according to the numerical algorithm to analyze the formation of urban heat islands with Using a series of mathematical functions and fractions, they finally designed a numerical model to study the heat island in urban and densely populated areas.

First, the average height of buildings in the area was calculated based on Equation (3). Examination of the height of the blocks showed that the highest height is related to the urban block with 24 meters and the lowest height is related to the urban block with 5 meters. Therefore, by examining the height of urban blocks, it was estimated that the number of blocks with an average height of 10 to 12 meters is more, the number of these blocks is 99. Therefore, in areas two and six, most urban blocks have an average height of 12 meters, in other words, each urban block has an average of 4 floors. According to the classification of the average width of passages, out of 227 urban passages in the region, 123 passages have an average of 21 meters. Therefore, the maximum width of the passages in the area is 21 meters. Also, in the northeastern parts of the region (District 6) and the southwest of the region (District 2), the width of the passages has reached 26 meters, which is due to the location of these areas near the highways leading to these areas. In total, in areas two and six, most of the passages have an average width of 21 meters.Then the output of the Oak equation showed that the larger the ratio (H / W), the higher the heat island of the city (Table 1 Appendix). It can also be said that in most areas there was homogeneity between the height and width of the passages. The intensity of the heat island in the areas showed that the range is between 4-7 degrees Celsius, there is not much difference in terms of the intensity of the heat island in the whole region. The reason for this can be considered as proper planning and proper management in the field of how the buildings are located in relation to the width of the passages and observing the principles of urban planning. The results of H / W with UHI showed that if there is heterogeneity between urban blocks, the intensity of UHI will be higher at lower H / W coefficients than at higher H / W coefficients. That is, the greater the heterogeneity between the height and width of the passages, the greater the intensity of the UHI. Also, according to the following diagram, it can be inferred that in the studied areas, the low coefficient of H / W ratio has caused that most of the blocks have a homogeneous distribution and therefore the intensity of the heat island in the study area is not significant.

In this paper, we have tried to investigate the effect of urban geometry on the maximum intensity of the heat island, using GIS tools and the parameters of urban blocks and the width of passages. The OK numerical equation was used to investigate the intensity of the heat island. The results showed that urban geometry (height of urban block and width of passages) as two input parameters (H / W) affect the maximum intensity of the heat island of the city. In the second and sixth districts of Tehran, most of the urban blocks have an average of 4 floors (ie 12 meters). Also, the width of the passages in most areas of the region is considered in proportion to the height of the urban blocks. OKE equation simulation study showed that with increasing H / W ratio, UHImax growth is more significant, this result is somewhat consistent with the study of Gonzalez et al. (2011) and Osaki et al. (2011, 2018). Finally, the intensity of the heat island in areas two and six of Tehran's third district has not been felt, which indicates the proper configuration of the geometry of the buildings using the indicators used in the principles of architecture and urban planning in this area. Therefore, it can be said that this proposed model (OKE) can help to understand urban problems. Therefore, with proper planning and observance of urban planning guidelines by organizations and competent individuals in order to create better conditions, more targeted strategies can be adopted that can prevent the spread of the heat island phenomenon in large cities, including the metropolis of Tehran.

Having sustainable human capital leads to the adoption of strategies which make rural families resilient to risks, especially drought. The purpose of this study is to investigate the role of human capital in climate drought management in rural areas of Kermanshah. The present study is an applied research in terms of purpose (type of use), and the method used in this research is a descriptive-analytical method. The statistical population of the study, including all experts related to the subject of research in Kermanshah, is made of 120 people. The sample size was selected for 120 experts based on the total census. Data collection tools include two questionnaires of human capital and drought management. Moreover, the human capital index has sub-indicators that include (expertise, skills and knowledge). The validity of the questionnaire was formal, which was confirmed by university professors, and the total reliability of the questionnaire, based on Cronbach's alpha, was 0.84 and was proven. The collected data were analyzed based on the path analysis of structural equations. The results showed that human capital in general is effective in drought management. Among these, human capital sub-variables, which include knowledge, skills and expertise have also affected drought management, so that knowledge on drought management with an impact factor of 0/26 and a significant value of 0/002, drought management skills with an impact factor of 0/34 and a significance of 0/000, and specialization with an impact factor of 0/49 and a significance of 0/000, have affected drought management. Among these, expertise had the highest impact, while knowledge had the least impact.

The purpose of this study was to investigate the relationship between Eurasia-Northern Atlas Blockings with more months and dry years in Iran. For this research, rainfall data from 43 synoptic stations in Iran, geopultaneous geopultaneous height data were used and blocking components from 1973 to 2018. To check the blockings, the Blocking intensity index (BI) was used. The extraction of dry and more comprehensive months of ZSI index was used. The results of rainfall data showed that dry months have occurred almost 3 times more than more months, and the rapping of low pressure and low pressure have had the highest strength and severity in the North Atlantic region. The monthly relationship between blocking components with more months showed that the relationship was more months with abundance and severity. With the abundance of the frequency and severity of the casters, they have also increased, and whenever the severity and frequency are lower, Courses in Iran have also been reduced and dried months have grown in Iran. In terms of location, the nucleus formed between 30 and 55 degrees north and 30 + 30 - in the Atlas area have had the greatest effect on Iran's inclusive frustrations, because the formation of blockings in the blue zone is more energy and more power. But whenever Blockings are formed during 50 to 90 degrees, drought has increased. The results of multivariate regression test between blocking and tractory components (drought) showed that the effect of blocking components on Iran's wrapes was about 96% and drought was about 84%.

Cyclonic systems are generally unstable conditions messenger that result from the spread of significant disturbances that occur in atmospheric currents. In this study, daily rainfall data of 4 catchments and gridded data (ECMWF) with 6-hour time steps and spatial separation of 0.25 * 0.25 from 1979 to 2004 were used. using with the cluster analysis method 3 atmospheric patterns were extracted. where the center of the trough in 500 and 700 hPa Stacking on top of each other, the geopotential height is the minimum and the geopotential gradient will be the maximum and will lead to the occurrence of the most cyclogenesis, Which occurred in the first pattern these conditions and resulted in average heavy rainfall of 38.6 mm. In the second pattern, none of the conditions of stacking on top of each other and deeping of the trough, and this has led to the lowest average heavy rainfall of 32.7 mm. In the third pattern, the condition of matching of the two centers of the troughs is established, but they do not condition of deeping trough And have led to heavy rainfall of 36/1 mm which is less than the first pattern. Also, the most cyclogeneses location in the eastern Mediterranean to Iraq, heavy rains caused by cyclones are born in this region. The results also showed that most of the moisture comes from the Red Sea. the subtropical jet stream plays a role in strengthening and ascending, in the north of Saudi Arabia and the Persian Gulf.

The main aim of this paper is to determine the capable areas for cultivating pistachio through considering of Geo statistical Analysis the major effective factors. The necessary climatic daily data of weather stations For the 300 synoptic stations, the station was set up by 2016. The topographic data include relief, slope, aspect, and TIN layers extracts from 1:250000 topographic maps of the region. The maps of land use and vegetation land cover were prepared from the 1:250000 maps of national soil and water Research Institute. The spatial analysis facilities of GIS were utilized for numerical calculation and the spatial geodatabase of the region was established. Then spatial and description data was entered into the data bank. Finally by overlaying analysis in ArcGIS, cultivated area was classified according to its capabilities. The results showed that 707273/88 KM2 Of the area (43%), Not suitable for spreading pistachio cultivation (Including altitudes and urban use and steep slopes, seaside and riverside streams, shoals, saline and swampy lands) and 585130/39 KM2 (35/57%) From the country of Iran Area Including plain areas and agricultural use) was recognized as suitable for the expansion of pistachio cultivation. These areas are located in the east and south east, center and northeastern Iran.

In this research, we are trying to determine the “beginning time” as well as the “end” of the climatic seasons; and we will focus on identifying the displacement of these dates, which is influenced by the “climate changes” and “descriptionAbstract The purpose of this study is to investigate possible changes and displacements in Iranchr('39')s climatic seasons due to climate change. To do this, temperature, relative humidity, water vapor, wind and cloud data for 36 stations were received from the Meteorological Agency over 40 years. The data were divided into two 20-year series to allow comparison. Daily temperature data for each clustering time series were determined, then by considering 7-day sequences, the beginning and end of the seasons. The designated times were tested using the Rayman model. The results of comparing the seasons in the two time series indicated that in all stations, changes in climatic seasons occurred from Insignificant to significant. Climatic seasons in Iran do not correspond to calendar seasons, and climate change, especially temperature changes in recent decades, has caused the seasons to shift and shorten and lengthen. Although the beginning and end of the seasons do not generally correspond to their calendar dates, most of the days of these seasons occur in its calendar periods. The changes that have taken place have not only affected the length of the seasons, and these shifts have also changed the quality of the natural seasons. Keywords: Climate change, natural seasons, cluster analysis, Rayman model of the qualitative conditions” created in them, compared to the past climatic periods. “Meteorological Organization” data has been used in this research. Forty years of received data, was divided into two groups of 20. Applying SPSS, each group was divided into four stages representing each seasons. From these stages, the beginning time and the end of seasons were determined and the accuracy of the obtained dates was controlled with the comfort indicators of the Rayman model. The results of the comparison of seasons in two time series indicated that, the changes occurred in natural seasons from an almost non-existent one in all stations. Climatic seasons in Iran are not compatible with the summer season and climate change, especially the change in temperature in recent decades, has caused changes and shortening of seasons. Most of the days in these seasons occur during its monthly periods, although the beginning and end of the seasons generally do not match their calendar dates. Changes have not only affected the duration of the season, and these changes have also led to a change in the natural quality of the season.

In this study, the relationship between mean zonal and meridional variations of westerlies with wet and dry periods in the western Iran was investigated. Therefore, the data cumulative precipitation values of the study area from Eropean Center for Medium-Range Weather Forecasts (ECMWF) version (ERA-Interim) with spatial resolution of 0.125*0.125 and also the geopotential height data of the version ERA5 with a spatial resolution of 0.25*0.25 degrees was received from the same center for the years 1979 to 2019.The Standard Precipitation Index (SPI) was used to determine the monthly wet and dry periods. So, to investigate the relationship between mean zonal and meridional variations of the westerlies with wet and dry periods in western Iran, the Middle East Synoptic Index (MESI) was defined based on variations of the westerlies from 25 to 45 degrees north latitude at atmospheric levels of 500, 600 and 700 hPa. The results indicated, that when wet periods occur in western Iran, MESI upper than the threshold and westerlies on the Middle East (Mediterranean and Red Seas) have a meridional flow. Whereas in dry periods, MESI is lower than the threshold and westerlies have a zonal flow. According to the results, no wet and dry periods was found, the value of which MESI was lower and upper than the threshold. Therefore, it seems that variations of the westerlies flow can be effective as one of the factors in formation wet and dry periods in the western Iran.

In this research, while studying climate conditions in the current period and analyzing changes in temperature, precipitation level, and the sunlight received, current conditions were also analyzed based on daily data from synoptic stations in the region, which had meteorological data recorded for at least 30 years. Given the environmental conditions necessary for the growth of rice, the availability of its phenological data, its high-low temperature thresholds, the Degree Day systems needed for the completion of its life cycle, and the phenological processes related to its economic production, a suitable agricultural calendar was specified. During the March-July period, this calendar showed variations in different provinces. Based on the current temperature conditions and the probable continued warming trend of the planet in the decades to come, nwoDscale was applied to the output from the atmospheric general circulation model MCdaH3 under  scenario using LARS-WG5 model. In this study, years between 1969 and 1990 were used as the base period, while years between 2046 and 2065 were studied as the future period. Temperature and precipitation conditions for the future period were simulated. Obtained output was then studied and compared with temperature conditions that were suitable for the plant to grow in the region. With some differences, results showed that the agricultural calendar for rice in Gilan and Mazandaran provinces will shift to winter. Given the different temperature conditions of Golestan province, its agricultural calendar will shift to spring.

Dust is influenced by the interaction of the atmosphere-Earth system and, by changing radiation energy, atmospheric chemistry and physics, affects the climate of an area. Due to the necessity of the role of dust and its spatial-dynamic distribution in the atmosphere of a region, as well as the existence of advanced remote sensing techniques and modeling in the field of dust simulation, the present study attempts to compare, quantize and simulate dust using aerosol optical depth (AOD) of MODIS and MACC products. Pearson correlation showed that there is a significant relationship between the sensor and the model in the west of the interested area. The lowest correlation was observed over Hamadan province. The results showed that simulated dust was more than satellite observations. The annual dust revealed that dust have two active (2000-2010) and inactive from 2010 onwards. In addition, monthly distributions of Dust in MODIS and MACC showed that the interested area had the highest dust concentration in the months of April to August; it was high overlaps of AOD between MACC and MODIS in the wet months (December to March) than dry month (April to November). In general, the spatial distribution of dust in the study showed that the dust pattern in both the sensors and the model has increased from south to north in Kurdistan, Kermanshah and Ilam, but the spatial variation of dust in the MODIS is more regular than the MACC. In general, the spatial distribution of dust had the South-North trend and northward decreased

Probability distributions and different mixed regression models are used to study of wet and dry spells. In this study, eight stations on the southern coast of the Caspian Sea were used for 55 years (1960 to 2015). One and two day wet spells are the most frequent in the area. Also, four and higher days wet spells in the western region is more than the east. The best probability distributions of wet spells are two-parameter gamma, two parameter normal log, two parameter logistic log, four-parameter generalized gamma, generalized three parameters gamma, two-parameter gamma, three-parameter gamma and a three-parameter logistic log. Also, the dry spells of the region are better fitted with generalized Parto, generalized logistics and generalized extreme value distributions. Due to the random behavior of the annual wet and dry spells, the best generalized linear mixed model for wet spells is the negative binomial log, Log Poisson, log normal and gamma logarithmic, also the Log Poisson, log normal and the negative binomial distribution was determined for the annual dry spells.</div>

The aim of this study is to investigate synoptic change's monsoon system, South East Iran. Since precipitation is indicative instability and influx moisture, Precipitation's sweeping of the area was considered as a base to expand monsoon into Iran. The data include precipitation in synoptic, rain-gauge stations and NCEP-NCAR data. Grad's software was used for mapping. The results showed that in surface, the establishment of a broad low pressure in the Persian Gulf, Pakistan and expansion tab of Turkey high-pressure for a trough along the Zagros is responsible for the spread of monsoon. In 500 ha in events 1, 2 and 4, create a trough and positioned in the eastern areas in front its and in the third event the sawed-off tabs Russia for Cutoff low on Afghanistan, caused monsoon system penetration into the Iran. The profile of the area Omega is representing negative Omega at this time. Following lines showed the establishment the cyclone over the Indian Ocean in events 1, 2 and 4 and on Afghanistan in event 3 the groundwork for expanding the monsoon system. Events 1, 2 and 4 field of shared water systems that come from India, while the event 3 moisture is provided from Afghanistan that actually the tab moisture that has penetrated through India to Central Asia. Furthermore, monsoon expanded with positive vorticity is at ground level and negative vorticity at 500 hPa level.

Changes effective components in peak rainfall Iran. Introduction Since the spatial and temporal distribution of rainfall in Iran is influenced by the distribution of global circulation systems, the slightest change in its pattern is the severe weather abnormalities. Therefore, spatial and temporal abnormalities of rainfall and extreme changes in rainfall intensity and differences in precipitation types are one of the main characteristics of Iranian rainfall. Climate change is one of the problems of human society and is a threat to the planet Earth. The increase in the temperature of the earth has caused profound and extensive changes in the Earth's climate, causing changes in the time and place of precipitation, which has caused a lot of damage, especially in the last decade. The purpose of this study was to identify and study the changes in the heavy rainfall component of Iran in relation to changes in the systems middle tropospheric. Materials and methods First, the daily rainfall data of 53 synoptic stations were received from the country's Meteorological Organization from 1984 to 2013. The cluster analysis and zoning were done using Euclidean distance method and Ward's method was used. For zoning based on cluster analysis, seven variables of rainy day (one day, two consecutive days, three consecutive days, four consecutive days, five consecutive days, six consecutive days and seven days of continuous rainfall) were used. The final result was the division of the country into 3 regions according to the number of days. In the following, data from the upper atmosphere levels were used to investigate changes in the mechanisms of rainfall formation. Includes discovery data of geopotential heights, u wind, v wind, omega, level, 500 hpa, and specific humidity level 700 at daily average and 1 * 1 degrees from the European Center for Medium Term Forecast ( ECMWF) received. The statistical period of study was divided into two periods of 15 years (first study period 1984-1998 and second study period 1999-2013), The peak days for each area were determined in each of the two time periods. And for each time period The peak of rainfall was 5 days. Then, the synoptic parameters were analyzed and compared in each study period. Discussion In area 1 in the second study period, the range of trough decreased and the depth of trough increased. The central core of geo potential heights in the first time period is greater than the second period of study, in other words, the core in the first period is 5400 geo potential meters, which in the second interval decreased to 5350 geo potential meters. In area 2, in the second period of studies, the high elevation in the convergence region of the Arabian Sea is more shallow and in a more inappropriate position than the first pattern. In area 3, in the second study period, northwest of Iran is located behind the trough, and cold weather is falling and the rainfall in this part of the area is low. In 3 areas, in the second period of studies, the amount of moisture has decreased and caused the rainfall of the second interval to decrease compared to the first interval. Conclusions In the second period of studies (1999-2013), the range of trough has decreased and the depth of trough has increased. The Omega component study showed that in the second study period, the mean omega-negative peak of the peak days of the target area was reduced. The Omega component study showed that in the second study period, the mean omega-negative in the target area was reduced. It was also found that the direction of the wind streams in the second period was reduced due to the flow Linear more of the amount of precipitation. The amount of moisture in the second period of study has also decreased and has caused the second period rainfall to decrease over the first period. In the study of the synoptic components of area two, it was found that in the second period of studies (1999-2013), located on the convergence area of the Arabian Sea, is more shallow and in a more inappropriate position than the first pattern. And caused the maximum moisture content to fall to 5 grams per kilogram. In the study of the synoptic components of the third region, it was found that in the second study period, the study area, especially the northeast of the country, is somewhat ahead of the trough, and the average annual precipitation in this part of the area is increasing in the second period. And the northwest of Iran is located behind the trough and the cold weather has fallen. The rainfall in this part of the area has decreased. Keywords: Zoning, mechanism of precipitation. Middle troposphere, Iran.

This study investigates the effect of the QBO on the occurrence of heavy rainfall days in the southern part of Iran during the cold season. At first, QBO data from the Singapore station at 30 hPa level from the IGRA database and precipitation data for 89 stations in the southern half of Iran are also provided with daily time scale during the cold six-month period (January 1985 to end of April 2018) according to the 80th percentile (heavy rainfall) for each 6 month. Then, using IDW interpolation method, correlation maps were plotted for each month separately and six cold months Based on the obtained data, the QBO values were divided into 6 phases (three weak, moderate, and severe positive phases (+1 to +3) and three weak, moderate, and severe negative phases (-1 to -3)) and the number of days with heavy rainfall in each of these six phases calculated. Then, the zoning maps of the effective phases in increasing the number of days with heavy rainfall for each of the 6 months as well as for the cold months, were plotted. Based on the results, from November to January, the weak to moderate negative phases and the next three months, February to April, the weak positive phases were more likely to contribute to increasing the heavy precipitation days. Also, it showed that the highest number of days of heavy rainfall occurred at most stations in the weak positive phase (+1) in cold months

  The activity of synoptic cyclones plays an important role in determining the local climate and the formation of large-scale atmospheric circulation through the vertical and horizontal exchange of heat, humidity and momentum, coupled with interaction with large scale circulation centers (Zhu et al, 2001: 1523). The cyclones generally are transmitter the bad weather conditions and also represent the initial mechanism of transmitter moisture and heat to the pole. Systematic changes in geographical location or the intensity / frequency of cyclone activity will have significant disparities among other regional climate impacts (Wang, 2006: 3145).
The effect of mountainous obstacles on synoptic systems, especially the cyclone systems, has known. The mountain range is one of the factors, In addition to disrupting the face of the earth's uniformity, also disrupt the climatic uniformity. The purpose of this study is to determine the effect of thermodynamics of Zagros Mountain on the changes in cyclones entering the country from the west. For this purpose, the daily precipitation data of 13 stations of the Meteorological Organization in West of Iran were received. Also geopotential data were extracted from the NCEP / NCAR databases with spatial resolution of 2.5 × 2.5 degrees and ERA-Interim data from ECMWF databases with spatial resolution of 0.125 × 0.125 degrees, thier framework is 0 to 80 degrees east and 0 to 60 degrees north.
Using the Factor Analysis method, April 14th-18th, 2003 was selected as the best pattern. After selecting the sample day, sea level pressure maps and geopotential heights of different levels were prepared and analyzed. The result of the study of these maps showed that the cyclone reaching the Zagros Mountains, dynamically strengthened from the day it formed until it arrived in Iraq. When approaching the Zagros, the vorticity and its omega are reduced, but crossing Zagros, a positive vorticity increase happens. These types of cyclones call Zagros cyclones. The relationship between the amplified cyclone with the divergence region of the middle and middle levels were observed at all stages. The Zagros roughness, like a wall, initially causes the cyclone reached with Iran to weaken and become bipolar. But the passage of the cyclones from it, the thermodynamic conditions of the descending air in the lee mountain range, that makes them revival. As the roughness collides, a weak core remains in the Zagros range, and another nucleus is formed by passing through the mountains in the central regions of the country, and is reinforced in the next hours; and finally, the cyclone is amplified and it leaves Iran completely. These cyclones can be called zagros second cyclones. Mountain barriers consider as the factors destroying the homogeneity of the local climate.
Sometimes they act as the planets like the Rocky Mountains. Iran's land are heterogeneous due to elevations in the north, west, and other areas, Iran is heterogeneous in term of geomorphology and climatology.
One of the most outstanding effects of roughness on the climate is the change in the structure of systems passing through these barriers. Zagros Mountains is one of the main mountain ranges of Iran, with an almost northwest-southeast direction with a maximum height of about 4,400 meters zardkuh, has a significant impact on immigrant systems in the country.
A study on the cyclone on April 14th , 2003 showed that this cyclone was formed on the April 12th on the northwest of Europe, moving towards the Mediterranean Sea. its trough arrives in the country on the April 14th and it reaches the slopes of Zagros on the 16th. As Zagros is approaching, changes in pressure in the back and the lee of Zagros are increasing. Vorticity and divergences are completely different in two parts. In the altitudinal areas in the Zagros line, during a few days and during the passage of the cyclone, there is a negative vorticity. The vertical velocity also demonstrates subsidence in Zagros altitudinal areas. The results vividly prove that the cyclone is(get) weakened in collisions with the Zagros, and its movement gets slowness(slow), but it does not disappear. But also it is re-reinforced on the Zagros lee in the central of regions, and continued its route to outside the borders of the country.
Keywords: Lee cyclones, cyclonic vorticity, Vertical Velocity, humidity flux, Zagros

Azores subtropical high pressure is accounted as the most striking and permanent features of tropospheric circulation in the Northern Hemisphere subtropical region and Iran. Assessing the published sources about the subtropical high-pressure variations showed that a comprehensive research of the high-pressure changes is needed in different seasons of the year. Increase or decrease in the severity index and eastern and northern extension index of the subtropical high pressure of 500 hPa level, is a major determinant index of the arid and wet periods in Iran. Therefore, the main goal of this research was to determine the tempo-spatial changes of subtropical high pressure or in the other words determining the northern and eastern borders spread and also the intensity of this system in different seasons over Iran. For this purpose, the data with NC format and geopotential height of 12GMT over a period of 68 years (1948_2015) were downloaded from the databases of National Center for Atmospheric Prediction (NCEP) and the National Center for Atmospheric Research (NCAR) NOAA and for seasonal classification and drawing the intended maps, they were converted to standard and intended formats Intended in the next stage. The maps and time series charts of mean STHP of Iran’s atmosphere indicate an increase in the severity and surface index during all the seasons of the year. The slope of the trend line has been increased for all the seasons and the average of geopotential height in Iran increased at a rate of 5.87 Geopotential meter per every 10 years and in 2015 reached to the maximum positive anomaly.

This study aimed to evaluate the variability of summer precipitation in the South East of Iran was selected stations and the precipitation associated was investigated with IOD index. For this purpose was used weekly precipitation data from June to September stations of Zahedan, Kerman, Bandar Abbas, Iranshahr and Bam and weekly IOD index data. The method of this study is the correlation coefficient and discrete wavelet analysis. The results showed that in the positive phase of the IOD Index, warm air and humid of West Africa, sucked by low pressure the Persian Gulf and Pakistan and conditions creates convection in southeast of Iran, while IOD negative phase, in addition to shiftting the intertropical Convergence Zone, low pressure Persian Gulf and Pakistan are gone and West Indian Ocean for cooling than normal, stable atmosphere reigns. Summer precipitation correlation analysis between Bandar Abbas and Iranshahr with IOD index showed the strongest association. After the precipitation signal analysis of the stations showed of the Zahedan station on Level 4 and 3, respectively, at 99 and 95% was related to IOD index. The following series Kerman and Bam precipitation did not show any relationship with IOD index. Data analysis by the discrete wavelet transform showed that the most important cycle repeating 11-year occurred in the IOD index. Zahedan and Iranshahr showed periodic cycles relatively similarly. In Kerman was appeared 7-year cycle dominant and in Bandar Abbas and Bam the 11-year cycle. The process of reducing the number of weeks along with summer precipitation in the form of stations is contrary to the IOD index. But the increased intensity of precipitation stations is directly related to this index. Also Bandar Abbas, Iranshahr and Zahedan have more balanced precipitation cycles, but summer precipitation anomalies are intense in Kerman and Bam.

In this research in order to identify the most effective jet stream pattern, creating pervasive rain falls in Iran during the period 1971 to 2008, from turning approach to the environmental approach was used. For this purpose, first of all, an elemental analysis with component based approach on wind speed data with the balance of 300 HP for 12 of Zolo was done by demystified data of United States of America Atmospheric Prediction Center. The analysis showed that 8 main components are able to explain 85% of the diffraction of data. Then, by applying a hierarchical cluster analysis with Ward's method on the scores 8, mentioned component during the 3098 days under study, eight prevailing jet stream was detected on Iran. Then for every pattern, using the interclass correlation, one day with the most correlation was chosen as the day of an agent of that pattern. The next step is to determine the most effective model jet stream leading to rainfall, the amount of rainfall of 32 synoptic stations in the center of provinces, along with maps in heights, Omega, 1000, and 500 hp and map the convergence of moisture flux for levels of 700 and 850 hp for each of the days of the agent was investigated. The results showed that the pitch of strong jet stream in fourth pattern with a speed of 65 meters per second at the level of 300 hPa in southern of Iran along with formation of through cold Chali on the Caspian Sea, simplify the conditions for the convergence of the lower levels of Iran atmosphere, and influx of moisture from the Mediterranean Sea along with along with unstable conditions of high atmosphere, causing pervasive rain in Iran.