saeed jahanbakhsh

In this study, the prediction of precipitation and temperature values using the general atmospheric circulation models during 1964-2005 is investigated. Climatic data including daily values of total precipitation and mean temperature were obtained from the Iranian Meteorological Organization. Considering the climate change scenarios RCP4.5, RCP2.6 and RCP8.5 for the coming period 2010-2100 were evaluated under the canESM2 climate change model of Aharchai Basin. Due to the low accuracy of the general circulation models, the SDSM4.2 miniaturization model was used and the changes in precipitation and mean temperature parameters were simulated for future time periods. In this study, to calibrate the SDSM model, among the 26 large scale climate parameters (NCEP), on average, 3 parameters have the highest correlation with the mean temperature and 5 parameters have the highest correlation with the average precipitation in the Aharchai Basin. The results of climatic parameters prediction showed that simulation of climatic parameters mean temperature was performed with higher accuracy than mean precipitation values. The reason is that the precipitation data are not normal and unconditional. The results show that the basin temperature averaged more during the period 2070-2099 under the scenario RCP8.5 than the observations period of 1964-2005 and the basin precipitation during the period 2070-2099 under the scenario RCP2.6 showed the highest increase in the entire study period.

In recent years, South-east and east of Iran has become one of the most important hotspots of dust events due to numerous droughts, upstream dams and severe land use changes. In order to evaluate the seasonal variations of dust, 15 synoptic stations were selected during 1980–2015 and then extracted from the present weather codes. Additionally, the AOD index of the Terra MODIS satellite sensor and the Aura Satellite Aerial Index of Absorption (AAI) were used during the period 2015–2005. Mann-Kendall nonparametric test was used to investigate the trend of dust days and Spearman correlation method was used for correlation of dust days. The average days of dust in this region are 9 days and maximum days of dusty days are 45 days that occur in Zabol station at summer. Intra-seasonal variations of dust over east and southwestern of Iran have two maximum phases at spring and summer. Dust also has an inverse relationship with altitude and latitude. Climate parameters, drying up of rivers and lakes, and land use changes are three major factors in dust production in eastern and southeastern Iran. Main sources of dust production and emission over the region are (1) Makran coast; (2) Hamoun and Jazmourian dried bed (3) Lut Plain and (4) Border region of Iran, Afghanistan and Pakistan. At most stations except Zabul, Bam and Kerman have an increasing trend of dust events.

In global meteorological literature, atmospheric rivers are defined as long and narrow pathways of intense water vapor transport towards the polar regions in the middle latitudes, typically associated with low-level jet streams along the leading edge of extratropical cyclones. In this study, to identify the origins of the incoming atmospheric rivers to the study area, precipitation systems that occurred at more than half of the region's stations were selected. Then, using vertically integrated water vapor flux data from the east and north of the study area with a spatial resolution of 0.5 x 0.5 degrees, the magnitude of the water vapor flux was calculated. To calculate the magnitude of the flux, data including specific humidity and meridional and zonal winds at pressure levels from 1000 to 300 hPa were used. showed that these rivers have entered northwest and west of Iran from four moisture sources. The sources are the warm southern seas (the Sudan - Red Sea low-pressure pattern), the convergence zone region, the combined source of the Sudan low-pressure system and the Mediterranean circulation, and the Mediterranean Sea. Among these sources, the warm seas of Arabia and Oman and the Red Sea had the largest share in the incoming rivers to the region. These atmospheric rivers have been the strongest in terms of both temporal continuity and moisture flux. They first enter southwest Iran and then into the study area. The atmospheric rivers with the convergence zone source rank second in terms of their contribution to the region's precipitation.

the statistics of the ECMWF database were used for the observation data of the two stations of Semiram and Urmia during a 21-year period (1996-20016).In order to investigate the effects of climate fluctuations, the daily data of dynamic micro-rotation of the CORDEX project was used for the output of the ICHEC-EC-EARTH model under the RCP8.5 and RCP4.5 radiative forcing (RCP) scenarios for the period (2017-2037). By using the data of the stations and the outputs of the micro scale model, and by using the perceptron neural network and linear regression, the performance was simulated. Then, to evaluate the efficiency of the models, R, R2, MSE, RMSE, and NRMSE statistics were used, and the non-parametric Menkendall test and age slope were used for the performance trend. The result of comparing the output of artificial neural networks with the linear regression model shows that the error rate of the neural network is less and the simulated results are close to the real observations to a very acceptable extent. The phenological stages, including bud blooming to fruit ripening in the stations under both scenarios, and in all the phenological stages in the future period will be completed earlier than the base period, and the length of the growth period will also decrease. The amount of future yield in Urmia station under RCP4.5 and RCP8.5 scenarios respectively yield 3.7 and 2.2 tons per hectare and in Semiram station yield 1.4 and 3 respectively tons per hectare will decrease. The results show that in the future in the study areas, with the change in the time of occurrence of the length of the growth period, all the phenological stages as well as the declining performance of apple trees will be subject to climatic fluctuations

In the current research, to investigate the future climate of the Urmia Lake catchment, the maximum and minimum temperature, rainfall and drought in the basin were projected for the period of 2015-2099 using NorESM2-MM climate model under the scenarios of SSP. The downscaling output of the model was done using the quantile mapping method and their accuracy was evaluated in the simulation of the base period (1990-2014) using the monthly diagram and RMSE and NRMSE indicators. The evaluation of the results showed that: the minimum and maximum temperature of the basin under the pessimistic scenario (SSP5-8.5) until the end of the century and under the optimistic scenario (SSP1-2.6) until 2075 have an ascending trend and then a descending trend. Average maximum and minimum temperature of the basin in the near future (1.0 to 1.8) and (1.1 to 1.8) ℃ and in the far future (1.5 to 4.8) and (1.3 to 4.3) ℃ will increase. The annual rainfall in the future period does not have a significant trend, but the average rainfall of the basin in the optimistic scenario will increase by 16.5% in the near future and 8.9% in the far future and in the pessimistic scenario will increase by 1.8% in the near future and 7.2% in the far future. According to the SPEI index, in the future period, under the optimistic scenario, moderate drought will have an ascending trend, severe drought will have a descending trend, and under the pessimistic scenario, the drought will have a descending trend.

For this purpose, data on the type, amount, and height of different cloud layers and daily precipitation of 36 synoptic stations located on the southern coast of the Caspian Sea were received from the Meteorological Organization. MODIS images were used to investigate the relationship between precipitation and cloud microphysical parameters (CTT, CTH, COT, CER, CWP). ERA5 and NCEP/NCAR data were also used to identify synoptic patterns leading to cloud formation. Finally, HYSPLIT model and regression method were used to identify the path of moisture flow. The results of observational data showed that Caspian clouds were observed in the form of low Stratus clouds and middle clouds of Altocumulus type in the region. So that among the low clouds, the heights of 750 and 900 meters and among the middle clouds, the heights of 2700 meters had the highest frequency. The results of Caspian clouds rainfall showed that in most areas, 1 to 5 mm of precipitation has occurred. Correlation results showed that precipitation was positively correlated with CTH,COT, CER and CWP, and negatively correlated with CTT. Multivariate regression predicted 17% of precipitation by cloud parameters. The results of the study of synoptic maps showed that with the establishment of a 1012 hPa high pressure core in the north of the Caspian Sea, the north-south wind flow along with the transfer of sea moisture to the south shore of the Caspian Sea, ascending the air mass and the formation of clouds and limited rainfall in the region. Vertical profiles showed maximum specific humidity in the lower levels of the atmosphere (1000 to 900 hPa). The results of HYSPLIT model moisture flow path showed that the main source of regional moisture was the Caspian Sea.

Earth surface temperature changes can affect various environmental factors and elements, and by affecting bioclimatic comfort, energy consumption, plant and animal phenology, air pollutant concentration, soil and air moisture density, and other environmental factors can also be affected by these factors.In this research, in order to investigate the role of actual evaporation-transpiration on the temperature of the earth's surface at ten meters, the variables of carbon monoxide, water vapor density, nitrogen dioxide, sulfur dioxide, ozone, water vapor pressure and wind speed in twelve uses With the help of LCZ algorithm, determined for Tehran and Alborz provinces, have been studied and investigated.The studied area has a high potential for the occurrence of thermal islands due to special geographical conditions such as location, variety of man-made structures and special ecological conditions. In this research, according to the impact of the studied variables and the need to examine the relationships between them, hierarchical clustering in a combined manner, path analysis method and remote sensing techniques have been used. According to the obtained results, among the studied variables, actual evaporation-transpiration in none of the uses had a significant effect on increasing or decreasing the temperature of the ground surface at 10 meters. Water vapor pressure in class 14 (areas with grassy vegetation) shows the greatest effect in increasing the temperature of the earth's surface.Based on the obtained results, the type of use is highly dependent on the impact of the studied variables on the surface temperature of the earth.

In this research, the performance of CMIP6 general circulation models has been evaluated in the simulation of temperature and precipitation in the catchment area of Lake Urmia. The models used are MPI, CMCC, INM and MRI with a spatial resolution of 100 km. The performance of the models was evaluated before and after the bias correction. To correct the bias of the models, the statistical method of the delta factor change and the data of seven synoptic stations at the basin level have been used. For this purpose, the studied period (1990-2013) was divided into two twelve-year periods for calibration and verification. In this way, the accuracy of the corrected data of the models was evaluated using the delta factor change for the period of 2002-2013 compared to the observational data by using R2, RMSE, NRMSE indicators and Taylor and scatter diagrams. The results showed that for the entire basin, there is a strong linear relationship between the corrected data of models and station observations for temperature and a weak linear relationship for precipitation. The RMSE and NRMSE indices indicate the high accuracy of the models in simulating the monthly temperature and relatively weaker accuracy in simulating the monthly rainfall of the basin, and among the models, CMCC had the highest error. The spatial distribution maps of NRMSE for the total monthly averages showed that all four models have simulated temperature with high accuracy, but the simulation of precipitation in some areas of the basin does not have acceptable accuracy. Therefore, the performance of the studied models was evaluated as good in temperature simulation and poor in precipitation simulation, especially in the CMCC model.

Determining the temporal change of snowmelt or agriculture water equivalent of snow, predicting flood, and managing the reservoirs of a region is of utmost importance. Some major parts of the western sections of the country are located in the mountainous region and most of the precipitations of this region occur in the form of snow in winter. The runoff resulting from snowmelt has an important role in feeding the rivers of this region and it has a significant share in developing agriculture and the economy.Scientific studies have shown that climate change phenomena have significant effects on precipitations, evaporation, perspiration, runoff, and finally water supply. As the demand increases, climate changes, greatness, frequency, and the damage resulting from extreme weather events, as well as the costs of having access to water increase, as well. Therefore, evaluating the runoff resulting from snowmelt and the effect of climate change seems necessary for managing water resources.

Gamasiab basin is located in the northeast part of the Karkheh basin originating from the springs in the vicinity of Nahavand. Its basin has an area almost equal to 11040 square kilometers that have been located in the east part having 47 degrees and 7 minutes to 49 degrees and 10 minutes geographical longitude and from the north part, it has 33 degrees and 48 minutes to 34 degrees and 54 minutes geographical latitude. This basin has an altitude between 1275 to 3680 meters.In this study, snow-related data required for simulation were derived from the daily images of the MODIS sensor. To this end, first, the snow-covered area of the Gamasiab basin was measured during the 2016-2017 water years using the process of satellite images obtained from the MODIS sensor in the google earth engine system. All geometric justifications and calibration processes of images were applied precisely in the mentioned system. In the next step, the output of the GCM model scenarios was utilized for calculating temperature and precipitation changes in future periods. These CMIP5 kind models were under the control of two RCP45 and RCP85 scenarios and were downscaled with LARS-WG statistical model.Moreover, to investigate the uncertainty of models and scenarios, the best models and scenarios were selected for producing temperature and precipitation data of future periods; accordingly, the outputs of the models for future periods (2021-2040) having the basis period of (1980-2010) were compared using statistical indexes of coefficient of determination (R2) and Root Mean Square Error (RMSE). The results were entered into the SRM model as the inputs. In addition, temperature and precipitation data of meteorological station of the studied region as well as the daily discharge of the river flow of hydrometric station of Chehr Bridge (as located in the output part of Gamasiab basin) were used during the statistical period of October 2016 to May 2018.  

Using Digital Elevation Model (DEM) of the region and the appendage of Hec-GeoHMS in GIS software, firstly, flow direction map, flow accumulation map, and stream maps were drawn and the output point (hydrometric station of Chehr Bridge) was introduced to the border program of the identified basin and the basin was classified based on the three elevation regions.Producing temperature and precipitation data of future periods requires a long-term statistical period; accordingly, the meteorological station of Kermanshahd was selected since it was in the vicinity of the studied region. To be confident in theability of the model in producing data in future periods, the calculated data had to be compared with the observed model and data in the studied stations. The capabilities of the LARS-WG model in modeling the mentioned parameters of this station confirmed the observed data. Moreover, the ability of the model in modeling precipitation was very good and acceptable; however, the most modeling error was related to the precipitation in Mars.In the next phase and compared to the basic periods, the mean of changes in average precipitation and temperature was measured in the studied stations during January and Juan of 2015 to 2017(for which simulation had occurred); as an index of changing the climate, this was entered into the SRM model under climate change conditions. During the simulation period (January to Juan), it had been predicted that the precipitation parameter would decrease and the temperature parameter would increase.

The results of this study indicated that using the MODIS sensor could provide an acceptable estimation of the snow cover level of the Gamasiab basin, which lacked snow gauge data. Moreover, the results of simulation with the SRM model showed that the model could simulate the snow runoff in the studied region. As the main purpose of the study, the effect of temperature and precipitation in future periods was well stated considering the uncertainty of CMP15 series models and scenarios. The results of temperature changes indicated an average increase of 1.8 C. the results of precipitation also indicated an average decrease of more than 5%. However, decreasing precipitation in the cold months of the years had been predicted severely so that the reduction of precipitation in February was of utmost importance for feeding the snow cover and rivers, which had been estimated to be 20%. This happened while increasing precipitation was mainly related to the hot months of the year whose amount was insignificant and didn`t have that much effect on the runoff. Accordingly, due to the increases in temperature and decreases in precipitation in cold seasons, the results of runoff simulation have indicated a 24% reduction for 2016-2017 and a 29% reduction for 2017-2018 water years.

Any change in the concentration of greenhouse gases will upset the balance between the components of the climate system. But, the change in the concentration of these gases and how they will affect in the future is unknown. To study the effects of climate change on different systems in the future, climate variables must first be simulated under changes in greenhouse gases (climate scenarios). There are several ways to do this, the most reliable of which is the use of climatic models. AOGCMs can simulate climate parameters globally in large scale, while these may not be suitable for small scales. One of the most important downscaling methods is dynamic methods that are based on increasing the resolution and analysis of planetary climate models. Here, in this research, climate change status in Karkheh River Basin where a major basin for water and agricultural yields is studied. For this purpose, the PRECIS model was used. PRECIS is an exponential dynamics downscaling model used to estimate the temperature and precipitation rates for the period of 2070 to 2100 under A2 and B2 scenarios. According to the results of climate change assessment under scenario A2, precipitation would increase up to 11% and up to five degree centigrade would rise in average maximum and minimum temperature while concerning B2 scenario, an increase in precipitation up to 7% and a rise in temperature rise up to three degree centigrade are estimated. However, under both the scenarios, despite, the fall’s precipitation is higher than the winter’s precipitation.

Cyclones constitute one of the major factors determining climatic conditions, especially precipitation in the middle latitudes. Changes in the properties of cyclones in a region may lead to variations in the precipitation conditions of that region. Therefore, studying major aspects in cyclones can clarify variations in precipitation conditions. In this research, changes of cyclones associated with precipitation in the Zard Rud basin (a Sub-basin of Jarahi basin in khozestan) has been reviewed decadal during a period ranging from the hydrological year of 1976-1997 to 2013-2014. In this research, daily precipitation maps during the studied period (13879 days) by using kriging method has been provided.

So the long-term precipitation mean of all days were extracted and by using 50 percentile, rainfall season detected. Upon identifying the precipitation season, Cyclones detected for this period. For identifying cyclones 1000 hPa hourly maps (NCEP/NCAR) were utilized. Two conditions were used to detect available cyclones: (1) the height values in each pixel of the 1000 hPa height map should be smaller than those of it 8 neighboring pixels and (2) the gradient mean of the height of the selected pixel and its 8 neighboring ones that was equal or smaller than 100 m/1000 km was regarded as the cyclone center. After identifying the cyclones on the map, the center of each cyclone was identified in consecutive maps to track the cyclone path. It was hypothesized that precipitation in the basin of the Zard Rud would be affected by the cyclones dominating the area as well as the trough of the cyclones that were far from the area, but could influence the region.

Cyclones associated with precipitation in the basin were identified in the light of the presence of the cyclone or its troughs over the region during the occurrence of a precipitation. The results show that The extent of the area and frequency of cyclones in studied decades and consequently frequency of cyclonic rainy days and annual cyclonic precipitation in Zard Rud basin have decreased. Reduction in the frequency of cyclonic precipitations can be attributed to the place where the cyclones are formed. Indeed, in comparison with the past, a larger number of cyclones are formed over Saudi Arabia and Iraq, a phenomenon which has led to the entrance of dry or less humid air into the studied region. Masoudian (2012: 15-33) also indicated that a cyclonic center was formed over Iraq.

Longitudinal extent area of cyclones decreases from 72.5˚ in first decade to 55˚ in fourth decade and Latitudinal extent decreases from 30˚ in first decade to 25˚ in fourth decade. Annual review on cyclones entry point to Iran show that minimum latitudinal extent from 1986-1987 hydrological year and maximum latitudinal extent from 1991-1992 hydrological year had fluctuation. So that, in 2011-2012 hydrological year, latitudinal extent of cyclones entry to Iran has reached the narrowest of its paths. Examining mean differences in the cyclone frequency of two halves of period (first half: 1976-1977 to 1994-1995 hydrological year and second half: 1995-1996 to 2013-2014 hydrological year) also revealed a noticeable shift in cyclones frequency. Result of surveying of cyclonic precipitation show that cyclonic total precipitation decreased during the studied decades. However, frequency of cyclones is less than first decade but second decade has the maximum amount of precipitation. It is may resulted of continuity of cyclones in this region. Taken together, a change was observed in geographical extent and frequency of cyclones associated with precipitation in the Zard Rud basin, which in turn affected precipitation in the area

Due to their height, geometry and orientation, the mountains affect the atmospheric currents. Therefore, mountains cause the formation, intensification or weakening of many atmospheric phenomena. One of the most obvious of these phenomena is lee cyclogenesis whose formation and evolution is subject to interaction between mountains and atmospheric currents. The lee sides of mesoscale or large-scale mountains, such as the Alps, Rocky Mountains, the East Asian mountains and the Andes, are favorable regions of cyclogenesis. This type of cyclogenesis is known as lee cyclogenesis, and can be defined as the formation of a cyclone with strong positive vertical vorticity or an appreciable fall in pressure with a closed circulation formed in the lee of a mountain that then drifts away (Chung. et al, 1976). In this regard, most studies have been made about the lee cyclogenesis of the Alps and the Rocky Mountains. As a result, the general understanding of mechanism of lee cyclogenesis is derived from studies conducted on these two mountains and partially due to the Alpine Experiment (ALPEX) field project held in 1982. In other words, the general framework of the mechanisms that exists today about lee cyclogenesis is based on the results obtained from the study of the Alps and the Rocky Mountains.

The variables used in this study are consists of horizontal wind speed (u and v), vertical wind speed vertical pressure coordinates (w), temperature (T) geopotential pressure levels (z). The data variables used 1 and 0.5 degrees in the horizontal and vertical distance of 50 hPa from 1000 to 200 hPa. The data were extracting from the archival database ECMWF ERA Interim version with six-hour monitoring. Preliminary investigations showed that unstable systems under certain elevation models are located in the middle of the atmosphere in the region of the west, northwest of the west and west to the upstream slopes of the Zagros Mountains. so that the study of middle - level maps showed how the trough and the ridge of such systems has played an important role in determining the direction and movement of these systems towards zagros because it is different in terms of the confluence or diffluence system, curvature and sheer vorticity advection and ageostrophic wind of the trough, and finally the direction in the trough. In general, the conditions prevailing on these systems and the it direction they pass through to the Zagros have an important role in how they interact with the zagros. Therefore, it is necessary to examine how these systems approach to Zagros. For this purpose, this important issue was further investigated using the ageostrophic wind equation. Because the ageostrophic wind indicates the imbalance of geostrophic, and in fact the change of wind both in space and time causes this imbalance of geostrophic and the creation of the ageostrophic wind (Lynch and Cassano 2006, 123). Also used curvature vorticity in the natural coordinates, quasi-geostrophic height tendency equation and divergence of the isallobaric wind.

An examination of the maps of the lower atmospheric levels shows that in some cases the cyclones approaching the windward slopes of the Zagros, under the baroclinic wave’s atmosphere, lead to the formation of a secondary rotation in the lee ward Zagros. Therefore, it is necessary to have a primary cyclone on the windward slope of the Zagros Mountains to form the lee cyclone. So the detection of cyclone approaching windward of the Zagros Mountains shows that cyclones which move and even higher than the Mediterranean latitude to the east, would have approached the Zagros in a way that was accompanied by a pattern of confluence ridge - diffluence trough in the middle of the atmosphere. While the cyclones, accompanied by a trough, were moving northward along the path of their eastward before reaching the Zagros in the north east. On the other hand, the cyclons, formed in the Red Sea region or Sudan, were required to reach the Zagros Mountains (the maximum velocity at the base of the trough) or the diffluence trough to approach the zagros. At the same time, the cyclones that were located in the area were under a confluence trough, never moved to the Zagros Mountains. So, according to the latitude of the primary cyclone and how the stack - trough is the level of 500 hpa, the path of the approaching Zagros is different. However, in many cases the nature of the trough and the level of the level of 500 hpa on the path of the eastward movement changes from difflunce to confluence and vice versa, which occurs due to the changing location in the baroclinic wave.

Because The Zagros Mountains create changes in approaching baroclinicity waves causes advent thermal anomaly and consequently cause the occurrence of cyclone, so, such cyclogenesis  is interpreted adjust according to the theory modify baroclinicity waves. Because this theory clearly states that mountain lead to lee cyclogenesis by modify baroclinicity. It is worth noting that many of the much complexities of the relationship between the Zagros Mountains and baroclinicity waves that may cause the occurrence of cyclones are a variety of other theories proposed in the literature to be more consistent Atmospheric Sciences. In any case, this study is based on small portions and a special kind of cyclogenesis can be in the Zagros leeward.

Strong winds are one of natural disasters that sometimes cause enormous Financial and physical damages. Since northwest of Iran and specially Ardabil Province is one of windy regions, this study tried to identify synoptic patterns which bring strong winds. Through considering equal and threshold wind speeding over 28 knots per second, 783 days identified as wind crashing days in Ardabil province. Then by data component- based analysis of 500hPa geo-potential height of the 783-days detected seven components which explain 92% of variance. Finally by clustering seven components identified ten patterns as synoptic patterns that are responsible for Strong wind of Ardabil province. The survey of topographic arrangement of these patterns indicates the rise of trough and ridge levels to these patterns. This means that the patterns consists of, mainly, trough, ridge, or combination of both and aren’t observed other systems such as cut off, block systems, etc. Although mentioned systems may be observe in individual patterns of each of the 783 days, but the systems aren’t responsible for the dominance and influence. The temporal distribution patterns show that  two patterns, 6 and 7which occurs in the summer, has a similar system at 1000 hPa level when it  compares with other models which occur in winter, spring, fall. What's notable, reversal of location position of pressure systems, 1000 hPa, in two patterns of summer, so that a low pressure instead of high pressure is over the Zagros and a high pressure instead of low pressure is over the Caspian Sea.

According to the importance of snowfall in supplying water of different regions especially mountainous areas, accurate estimation of snow water equvallent and changes of its coverage would be effective in agriculture, energy, management of reservoir and flood warnings. In this study runoff orginated from snow melting in ShahrChay basin under the terms of climate change calculated. For this purpose, snow cover for water year of 2012-2013 were extracted in ENVI software by using daily images of Modis satellite.Then, GIS software the physiographic specification of the basin was obtained. In the next step, data of snow cover, meteorological variables and other necessary parameters to SRM model provided as an input of model and run_off from snow melt was simulated. Then output of the 6 models of atmospheric general circulation with title of 3 scenarios nomely A1B , A2 and B1 converted to a downscaleing by using LARS-WG model. By comparing the output of 6 models in the future period to period based on monthly statistical, the best model and scenario for generation of air temperature and precipitation data in the period 2030-2011 were selected. As a result the HADCM3 model under the scenario A1B was used for generation of precipitation and the MPEH5 under scenarios A2 was used for generation of temperature data. In order to estimate the rate of change of runoff orginated from snowmelt rate of change of monthly data of air temperature and precipitation of the base time period as well as future time period under selected model and scenarios was entered to SRM model in simulation time period. Results for all of the scenarios show that runoff orginated from snowmelt in late spring will be reduced. The peak flow appeared earlier in comparison with base time period and its value would be larger than base time period.

Agriculture is the only activity which hurts the nature the least but becomes affected by natural circumstances, especially weather. Hailstone is among the most important dangers which make agricultural activities unstable through damaging agricultural products. Therefore, recognizing climates and studying climatological needs of agricultural plants, through fostering and utilizing human knowledge about atmospheric trends, leads to quantitative and qualitative improvement of products and subsequently stabilization of agriculture. Thus, the aim of the present research is the comprehensive study of temporal-spatial distribution and synoptic condition of these destructive phenomena For this purpose, the statistical data 23, 10 synoptic stations (2014-1992) in the growing season (April to September) with a choice of 4 cases of severe rainfalls and hail as well as data center NCEP / NCAR maps synoptic sea level 500, 850 and 1000 hPa cold wind, humidity, light, omega and frost formation in the application environment is drawn Grads. 9 to 15 (with peak rainfall at 12) Greenwich Mean Time GMT)) and the months of April, May, and June, respectively, had the highest frequency. The maximum frequency of occurrence in the region, in addition to local factors such as topography them (with altitude above sea level), the log-in system causing precipitation as west winds has an effective role. Located deep valleys caused by west winds with very cold air activities in the North, Mediterranean and Black Sea on the moisture, extreme temperature difference between the surface (due to the advection of warm, moist air at ground level) and high levels (with cold fronts) and ground-level air mass rally led by the highest frequency of hail in the spring (peak rainfall in April and May) is.

The Zagros Mountains, oriented from northwest to southeast, are barriers against western winds. This study was conducted to find a mechanism for describing specific type of cyclogenesis occurrence in the Zagros leeward. Therefore, by examining six cycles in this category, it became clear that as the cycle approaches the Zagros domains, there is an interaction between the cyclogenesis system and the Zagros Mountains, which leads to the formation of a particular thermal structure. Thus, a high pressure center is formed in the Zagros Mountains in the thermal winds. Such thermal abnormalities coincide with a decrease in static stability and dragging of the atmosphere and increasing relative tensile strength in the Zagros windfall. Then, perturbation potential vortices in upper levels stay on the lower perturbation potential temperature, atmosphere heat stress increased and cyclogenesis can occur in the leeward. On the other hand, the average underlying temperature (1000-700) and upper (500-300) levels showed that the most important effect of the mountains is to alter the mean distribution of low levels of potential temperature and hence to change the baroclinic waves. In fact, the Zagros Mountains, with increased meridional gradient of the potential temperature in the lower layer of the atmosphere, cause a sharp difference acceleration between upper layer and low layer of thermal disturbances. Accordingly, the Zagros Mountains, in terms of creating changes in the tilt of in Baroclinicity waves, provide the basis for the cyclogenesis in its eastern parts. So, this kind of cyclogenesis is based on the mechanism of orographic modification of baroclinic waves.

In this research, the impact of sea surface temperature on precipitation variation in southern part of Iran is examined using monthly data from meteorological and water resource institute during 1974-2005. The majority of precipitation occurs during the rainy season from October to May. Regional spatial precipitation on variability was identified by Empirical Orthogonal Function (EOF), applied to deterended monthly precipitation anomaly data. The first and second components, which determine 54 to 82.7% of the variance of the total precipitation from October to May were selected for the study. To study the rainfall variations, SST anomaly, moisture flux, geo-potential height and sea level pressure were analyzed for wet and dry years of first and second mode of EOF. The pattern of sea surface temperature anomaly for wet and dry years shows that the sea surface temperature of Indian Ocean has an important role on precipitation variation over the south part of Iran. In the first mode of EOF which represent 50% of total variance the positive (negative) sea surface temperature anomaly is in the East (west) part of Indian Ocean during wet (dry) years and it is associated with the equatorial easterly (westerly) moisture flux anomaly. In the second mode of EOF the SST anomaly over the Arabian Sea is positive in the wet years but it is a non-dominant feature for the dry years. The Arabian anticyclone has an important role to transfer moisture in lower level of atmosphere from southern water bodies to the cyclone near Iran and displacement of the Arabian anticyclone to westward (eastward) transports more moisture from southern water bodies to the western, south western (southern and south eastern) parts of Iran.

Central venous cannulation is a current and important procedure used in the operating room and intensive care unit. Some studies have shown that the application of ultrasound-guided cannulation can improve the success rate of surgery, save time, reduce the number of required needlesticks, and mitigate many complications compared to anatomical landmark-guided cannulation..
The aim of the present study was to draw a comparison between central venous cannulation of the internal jugular vein using ultrasound-guided and anatomical landmark-guided techniques..
Patients and A total of 321 patients scheduled for cardiac surgery in the surgical ward of a general hospital were randomly treated with central venous cannulation using either anatomical landmarks (150 patients) or ultrasound guidance (170 patients). The demographic data of patients, the success rate of cannulation, the execution time, and the number of attempts for successful cannulation as well as the complications were recorded and subjected to statistical analysis..
The success rate of cannulation was 98.7% in the anatomical landmark-guided group and 99.4% in the ultrasound-guided group. The average operation times were 46.05 and 45.46 seconds in the anatomical landmark and ultrasound-guided groups, respectively. The two groups were not significantly different in terms of the success rates of treatment, the number of attempts, the time required for successful cannulation, or the prevalence of complications (P > 0.05) other than carotid artery puncture (P = 0.04).
In our conditions, the use of an anatomical landmark-guided procedure was the preferred treatment method due to limited resources and a lack of adequate training..

Hydrologic drought can be studied in different ways. One of the common methods is the use of low flow indexes. In this study for the purpose of determine of the identity of aspects of low flow, the homogenous zones, the extraction of regional regression models, and finally, the study of low flow trends of Karkheh river basin, applied the data of 13 hydrometric stations during the statistical period of 1960-2000. After qualitative and quantitative controlling and the retrieval of missing data used flow duration curves for indexes such as Q75, Q90 and Q95. Also frequency analysis of 10-day, and 20-day low flows was carried out for indexes such as Q10,5, Q10,50, Q10,100, Q30,5, Q30,50, Q30,100 and some more indexes. Afterwards, some other factors like physiographic, climatic, geologic and vegetation cover were applied as influential parameters in the regional analysis. These factors were used in cluster analysis and stepwise regression estimations. Final step was the trend analysis of times series of the indexes. Results indicate that among the indexes being calculated, Q10,100 and Q95 had the minimum quantities, whose amounts reduced as the return periods increased. On the hand, the time spans of 1998-1999, 1999-2000, 2000-2001 have undergone severe and long droughts in most of the stations. The review of the spatial distribution of indexes show better conditions of the south-eastern parts of the study area compared to the northern and southern sections in terms of dryness. Results of cluster analysis divided the area into two distinct homogenous units (in 0.01 significant level). In the area No. 1, the elevation factor, in the area No. 2, the drainage density, and in general, the factors such as the mean of area and drainage density have the highest effects. The Spearman statistic, and Mann-Kendall findings also indicate that the low flow in upper basin have negative trend during the statistical period.

Precipitation acts as one of the most important elements of the climate. There has been much discussion and research in this regard. Spatial and temporal distribution of precipitation is very important in a place. This study aims at the understanding of the distribution of precipitation in specified time period for optimization of its use in agriculture, industry and human consumption. Estimation of flood and determination of the potential flooding and drainage system design, including the use of spatial and temporal distribution of precipitation is considered in the current research. To study the spatial and temporal distribution of precipitation in the city of Tabriz daily data from 11 stations were used for the period 1378 to 1388. To achieve the above objectives and zoning of the area in terms of precipitation, the first step was to prepare maps which were then converted to the data. Data were also used to remove cells outside the borders of original matrix that contained daily precipitation. The results showed that Tabriz county precipitation is separable into three distinct groups of with average precipitation, low precipitation and few others had some of the highest precipitation amounts.

Hydro-meteorology parameters are sensitive to climate change. Therefore, it is important to investigate the present climate change pattern and its impact on water resources. Changes in a series may occur gradually or abruptly. Both of these changes could be detected by non parametric statistical tests. In this research, mean annual discharge flow and mean annual rainfall were selected for detection trends in Karkheh Watershed, one of the mountainous watersheds in Iran, using the Wilcoxon and Spearman rank correlation tests. Result showed that, both studied variables exhibit decreasing trend in the selected stations. But, no step changes were found in the time series. The observed trend in the upper area of the watershed may adversely affect the human activities of the region.

Selection of anesthetic approach for lower extremity operations is often a controversial issue for anesthesiologists.. The aim of this study was to compare the incidence and severity of back pain between general and spinal anesthesia, and to find effective factors in developing postoperative back pain..Patients and In a randomized clinical trail, 148 patients with elective lower extremity surgeries were randomly allocated into two groups of 74. The first group received general anesthesia and the second group underwent spinal anesthesia. The incidence of back pain was observed and documented. The severity of back pain was assessed at the first, fourth and eighth postoperative weeks by visual analogue scale.. The mean of patients'' age was 35.50 ± 13.34 years. The incidence and mean of back pain severity among all participants were respectively 35.80% and 15.95% at the first week, 7.40% and 2.43% at the fourth week, and 1.4% and 0.27% at the eighth postoperative week. The incidence and mean of back pain severity in spinal group were respectively 39.2% and 18.11% at the first, 12.2% and 3.92% at the fourth, and 2.7% and 0.54% eighth postoperative weeks. In general anesthesia group, these figures were respectively 32.4% and 13.78% at the first week and 2.7% and 0.95% at the fourth postoperative week. No back pain was reported at the eighth postoperative week. The incidence and severity of back pain in the first week showed significant difference between the two groups, while the mean severity of back pain showed significant difference at the fourth week after operation.. Spinal anesthesia could be probably considered as the sole effective factor in the development of back pain after operation..

In comparison with fossil fuels which pollute the lower layer of the atmosphere, use of wind energy has many environmental and economic advantages. Wind is a clean and renewable energy resource and use of the energy in the recent decades has been welcomed so much in the world. Energy plays an important role in the development of each society. All different activities including housing, transport, industry and agriculture may be dependent on this source of energy. The use of clean and renewable energy such as wind has environmental advantages compared with fossil fuels. The increase of population and demand for energy has caused that wind energy potential is considered as an alternative source of energy. Wind speed is the most important parameter of the wind energy. This is used in the analyses relating to this energy because wind power has a cubic relation with wind speed. The parameters of Weibull distribution is used to estimate the parameters related to wind energy and determine the sites which have wind energy potential. Thus, it is important to use proper methods in the estimation. In this paper, 6 distinct methods for estimating parameters of Weibull distribution have been considered. For this purpose, 5 synoptic station which have adequate 3 hours wind speed data from 1987 to 2009 (23 years) have been selected. These stations are: Ardebil, Parsabad, Khalkhal, Zanjan and Khoramadare. The method of moments, empirical, graphical, energy pattern factor and maximum likelihood methods and probably weighted moments have been employed to estimate scale (m/s) and shape parameters (dimensionless) of Weibull distribution. For determining the best parameters estimating method using cumulative distribution function of the Weibull distribution (F(v)), expected values have been generated. The Chi square test has been used to select the appropriate method. Cumulative distribution function has also been used in order to calculate the probability that wind speed is smaller than or equal to 5 m/s. In addition to 10 m height, Weibull distribution parameters and parameters related to wind energy potential namely, wind power density (Wm-2), wind energy density (Kwh-1m-2), the most probable wind speed (ms-1) and the maximum energy carrying wind speed (ms-1) have been computed in 20 and 40 m. Among considered methods, method of moment because of having higher significance level and lower chi square compared with other methods has been selected as the best one to estimate Weibull distribution parameters. Using this method, scale and shape parameters of Weibull distribution at 20 and 40 m height has also been estimated. Then, wind energy characteristics, namely, wind power density (Wm-2), wind energy density (Kwh-1m-2), the most probable wind speed (ms-1) and the maximum energy carrying wind speed (ms-1) have been computed. The results have showed that at monthly time scale and in 10 m height, the maximum value of k was observed in Zanjan and Khalkhal stations on June and the lowest value of k in Khalkhal station in January. The maximum value of c was observed at Ardebil in Februrary and the lowest value of c at Parsabad in November. Using the wind power density all the stations are ordered as following: Ardebil, Khoramdareh, Khalkhal, Parsabad and Zanjan. This order shows that Ardebil has high potential of wind energy and Zanjan has the minimum potential. We can summarize main conclusions drawn from this investigation s following: In this study, among the considered methods, the method of moment is specified as he proper one and using parameters obtained from this method, features relating to ind energy in studied stations were estimated.• Among the studied stations, the maximum of wind power density is observed at rdebil. In this station, in 40 meter height the largest value of wind power density hich was equal to 491w/m2 is also observed. The minimum value of wind power density is observed in Zanjan which is equal to 107.2 w/m2.• The probability that wind speed is smaller than or equal to 5 m/s was calculated using Physical Geography Research Quarterly, 46 (3), Fall 2014 3 cumulative distribution function for the studied stations in 3 heights namely 10, 20 and 40 meter. The results showed that in 10 m height, among studied stations the highest probability belongs to Ardebil. After Ardebil station, the highest probability was observed in Khoramdare.• In 10 meter height, at Parsabad, Khalkhal and Zanjan in all the year the probability is lower than Ardebil and Khoramdareh. So, in these stations the operating possibility of wind turbines will be low.

Central venous catheter placement is a routine procedure for the management of critically ill patients; however, it is important to ensure its proper placement. A central venous catheter malposition may cause various complications, some of which can be fatal. We report an unexpected malposition of a catheter in the left internal jugular vein, where it entered into the left internal mammary vein. We think one of the influential factors for leading a guidewire and catheter into a nominated vein may be the left sided bevel of the needle at the time of internal jugular vein needle and catheter insertion. We were required to continue going towards the subclavian vein and accidentally turned into the left internal mammary vein.

Because of airway stimulations during bronchoscopy and lack of direct access to the airway, preferred method of anesthesia for rigid bronchoscopy is already controversial. In this study we compared inhalation anesthesia with total intravenous anesthesia (TIVA) for rigid bronchoscopy. Method and Materials: 30 patients aged 2-6 years were chosen divided into two same groups. Anesthesia in group I maintained with halothane and in group II maintained with remifentanil and propofol. Oxygenation, heart rate, respiratory rate, coughing, bucking, laryngospasm, bronchospasm were evaluated during and after surgery. Also operation success and surgeon’s satisfaction were recorded as well. Demographic findings were the same in both groups. Oxygenation and heart rate were more stable in group II (P=0.047 and P=0.026 respectively) but there was no significant difference in respiratory rate between two groups (P=1). Success rate was also similar in both groups but surgeon’s satisfaction was significantly higher in TIVA (P=0.003). There was not any significant different between complications in two groups. We suggest TIVA for rigid bronchoscopy because of better oxygenation, more homodynamic stability, surgeon’s satisfaction, lack of air pollution and less interference with surgeon’s visual field.