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Scince climatic models are the basic tools to study climate change and because of the multiplicity of these models, selecting the most appropriate model for the studying location is very considerable. In this research the temperature and precipitation simulated data by BCM2, CGCM3, CNRMCM3, MRICGCM2.3 and MIROC3 models are downscaled with proportional method according A1B, A2 and B1 emission scenarios for Torbat-heydariye, Sabzevar and Mashhad initially. Then using coefficient of determination (R2), index of agreement (D) and mean-square deviations (MSD), models were verified individually and as ensemble performance. The results showed that, based on individual performance and three emission scenarios, MRICGCM2.3 model in Torbat-heydariye and Mashhad and MIROC3.2 model in Sabzevar had the best performance in simulation of temperature and MIROC3.2, MRICGCM2.3 and CNRMCM3 models have provided the most accurate predictions for precipitation in Torbat-heydariye, Sabzevar and Mashahad respectively. Also simulated temperature by all models in Torbat-heydariye and Sabzevar base on B1 scenario and, in Mashhad based on A2 scenario had the lowest uncertainty. The most accuracy in modeling of precipitation was resulted based on A2 scenario in Torbat-heydariye and, B1 scenario in Sabzevar and Mashhad. Investigation of calculated statistics driven from ensemble performance of 5 selected models caused notable reduction of simulation error and thus increase the accuracy of predictions based on all emission scenarios generally. In this case, the best fitting of simulated and observed temperature data were achieved based on B1 scenario in Torbat-heydariye and Sabzevar and, A2 scenario in Mashhad. And the best fitting simulated and observed precipitation data were obtained based on A2 scenario in Torbat-heydariye and, B1 scenario in Sabzevar and Mashhad. According to the results of this research, before any climate change research it is necessary to select the optimum GCM model for the studying region to simulate climatic parameters.

Because of the strategic importance of wheat (Triticum aestivum L.) and lack of precipitation amounts in Khorasan Razavi province، identification of suitable areas and the right time for this crop by using weather and climate data will increase yield of it. In this research، data of daily minimum & maximum temperature، and rainfall of 9 synoptic stations of the province were investigated in a 20 year statistical period (1989-2008). Offering the suitable temperature for germination of autumn wheat in the Korasan razavi province، susceptible areas were detected and mapping only with an emphasis on precipitation elements and considering the threshold of 300 mm. Also، start، end and duration dates of rainfall were calculated likely 50 and 80 percent by using the climatic conditions of region and then، were drawn maps of the most suitable times of cultivation of rainfed wheat. The results showed that the city of Ghuchan and Nishaboor are the most susceptible areas of the province and other cities، except Gonabad and Sarakhs are semi- susceptible regions of rainfed wheat farming. Also the first definition based on the start date of rainfall on first of October is day that total precipitation comes 5 mm، set as the best definition of determination of start date of effective autumn rainfall. Thus، considering the probability of occurrence of 80 percent and accepting the risk of 20 percent، the most suitable date of rainfed wheat cultivation for cities of province include: Torbat-heydariyeh 19 Nov، Sabzevar 20 Oct، Sarakhs 19 Nov، Ghuchan 24 Oct، Kashmar 29 Nov، Golmakan 20 Nov، Gonabad 10 Dec، Mashhad 13 Nov and Neishaboor 13 Nov.

Dust storms are natural phenomena which occur in arid and semi-arid areas of the world. In this study، to evaluate the dust storms which occurred in Mashhad over a period of 30 years (1981-2009)، first، the number of days on which dust storms happened in Mashhad (days with a wind speed greater than 15 m. s-1 and horizontal visibility less than 1000 m) were identified and counted for each month; then، the average of storm days over the 30 years were calculated. The severest storm day was chosen and the amount of pressure، temperature and dew point in different layers of the atmosphere were obtained by radio sound during that day and the day before it، being plotted on thephigram by digital atmosphere software. After analyzing the thephigram، the most important instability indexes were calculated. Finally، to confirm the results، the synoptic maps of Geopotential and Isotherm were also considered. The results showed that most storms in Mashhad happened in early summer (June)، when warm air mass enters the area. The results also show that during December and January، there happened the fewest stormy days in Mashhad. The results also show that there was moderate instability before the stormy days and severe instability (SWEAT=431. 7) during the stormy days، indicating the strength of the storm in the region. Synoptic analyses also confirm the analysis of atmospheric vertical profile، both showing that the interaction of south warm and north cold air masses over the region caused severe instability of the air and created the dust storm.

One of the main consequences of climate change is its impact on agricultural water use that could face the water resources management with serious challenges. In this research, to examine climate change influence on sugar beet and wheat water use in selected plains of Khorasan Razavi province, minimum temperature, maximum temperature, precipitation and sunshine hours for 2 coming decades were simulated using LARS-WG5 model according A1B, A2 and B1 scenarios confirmed by IPCC. Then potential and actual evapotranspiration and effective rainfall calculated using Hargreaves-Samani and FAO methods respectively and were determinate water requirements of these plants on the next 20 years compared with the base period (1991-2010). The results showed that the minimum and maximum temperatures will increase at all selected plains and the highest increase in minimum temperature in wheat growing period under all three scenarios A1B, A2 and B1 respectively equal 30.9, 45.77 and 29.13 percent will be seen in Sabzevar and during growth period of sugar beet respectively above scenarios will be seen in Golmakan with 5.23, Neyshabur with 6.62 and Neyshabur with 4.77. Also precipitation will increase in all stations except Torbat jam and the highest rate of increase in wheat growing period under these scenarios, respectively 35.24, 35.56 and 42.49 percent will be seen in Gonabad and in sugar beet growing period, respectively 69.21, 80.95 and 70.19 will occur in Sabzevar, Gonabad and Sarakhs. The results also showed that the water requirement of these plants in most plains of province will not noticeably change except of Torbat jam-Fariman that will increase equal 17, 14 and 18 percent in the growth period of wheat and 19, 18 and 18 percent in growth period of sugar beet and Sarakhs that will faced with reducing equal 14, 15 and 15 percent in the growth period of wheat and 6 percent in the growth period of sugar beet according the above scenarios.

Drought is a weather condition which accompanies with lack of precipitation over a certain time periods that human activities in the area located under its impact will experience negative effects. In this research daily rainfall data of nine synoptic stations in Khorasan Razavi province in the static period of 1989 to 2008 were used. Standardized Precipitation Index for one-month and three-month scales was calculated and then drought and wet periods were determinated and counted. Monthly average of isobars, isotemps, iso- RH, and iso-PWC (6 months of autumn and winter) were considered for 20 years (1989-2008). Results showed that three cities, Sarakhs, Quchan and Gonabad in autumn and cities of Torbat heydariye, Sarakhs, Quchan, Kashmar and Gonabad in winter have experienced the most drought. Lowest dry autumn and winter periods, were related to the Kashmar and Nishabur stations respectively. Also consideration of every year drought situation of study period shows that in 2001, all stations have experienced different intensity (acute, severe and moderate) of this phenomenon, so this year was considered as the base year of droughts in the period under review and its synoptic maps were presented. The study of synoptic patterns in base year showed that despite of good conditions for precipitation (low temperature, high relative humidity and precipitable water content of cloud) in all months of autumn and winter, due to interaction of Siberian high pressure system with Azores high pressure system and strengthening of Siberian high pressure and its complete domination over the region, not only rainfall has not happened, but also local and orographic precipitation faced with constraints and therefore moderate, severe and acute droughts, occurred entire region of our study.

The most important part of the design and operation of the supplier systems of agricultural water requirement is the estimating of plant water requirement. In this study by using the LARS-WG5 model, downscaled the data of HADCM3 model according A1B, A2 and B1 scenarios that confirmed by IPCC, and was simulated monthly amounts of precipitation, minimum temperature, maximum temperature and sunshine hours in Khorasan Razavi province in the period 2011 - 2030. Then using OPTIWAT software, reference evapotranspiration and effective rainfall calculated with Hargreaves- Samani and FAO method respectively and finally the water requirement of sugar beet was estimated in monthly scale for the two next decades compared with the base period (1991-2010). The results showed that spring and autumn precipitation in the future period will be increased in all stations except Torbat Jam compared with the base period. Most increase of precipitation equal 26, 21 and 16 percent based in A1B, A2 and B1 scenarios compared with the base period is owned Mashhad Station and will occur in April. Also according simulation of LARS-WG5 model, Minimum and maximum temperatures will increase during 2011 to 2030 and the increase of the minimum temperature is more than maximum temperature. As a result of these changes, the water requirement of sugar beet in 20 next years in most of the city of Khorasan Razavi province will be different compared to the current period. So that the Torbat Jam station under scenario A1B, A2 and B1, respectively 19, 18 and 18 percent and in the Golmakan respectively 15, 17 and 17 percent, water requirement of this plant will increase from the period of development until the beginning of the final period of growth and in Ghuchan, Nishabur and Mashhad will decrease in the middle period of growth. The most amounts of the reducing in water requirement equal 10 percent and belonging to Ghchan station. The results of running OPTIWAT software also showed that in Sarakhs, Gonabad, Kashmar and Sabzevar, would not happen perceptible change in the amount of water requirement of this plant in the next two decades compared with the base period.

Development and evaluation of mitigation strategies are very crucial to manage climate change risk. Research objectives of this study were (1) to quantify the response of maize grain yield to potential impacts of climate change and (2) to investigate the effectiveness of changing sowing date of maize as a mitigation option for Khorasan Province which is located in northeast of Iran. Two type of General Circulation Models (HadCM3 and IPCM4) and three scenarios (A1B, A2 and B1) at four locations (Mashhad, Birjand, Bojnourd and Sabzevar) employed in this study. Statistical downscaling method was applied for developing quantitative relationship between large scale atmospheric variables (predictors) and local variables (observes), and generating daily climatological variables performed by LARS-WG stochastic weather generator. The CSM-CERES-Maize model was used to achieve study objectives. The result showed that the simulated grain yields of maize gradually would decrease (ranged from -1% to -39%) during future 100 years compared to baseline under different scenarios and two GCM at all study locations. In general, Bojnourd experienced the highest simulated grain yields of maize under A1B scenario (12234 Kg/ha), A2 scenario (12662 Kg/ha) and B1 scenario (12653 Kg/ha) during the period of 2010-2039 by planting date of 19 June. Sabzevar experienced the lowest simulated grain yields of maize under A1B scenario (3320 Kg/ha), A2 scenario (2370 Kg/ha) and B1 scenario (3582 Kg/ha) during the period of 2070-2099 by planting date of 4 June. Delayed sowing of maize crop (from May to June) at all locations, except for Sabzevar is the most effective management factor in mitigating the thermal detrimental effects.

Evapotranspiration is one of the most important parts of water cycle in the nature but, the measurement of actual evapotranspiration (via Lysimeter as an exact measurement instrument) is so difficult and not practical. Therefore, equations that can estimate the value of evapotranspiration only by using meteorological data are necessary. In this study, four different reference crop evapotranspiration of Penman-Montith FAO56 (PMF56), Penman-Montith FAO with Irmak Radiation (PMFI), Jensen-Hais1 (JH1) and Jensen-Hais2 (JH2) have been assessed in a semi-arid climate of Iran to estimate the ETo. The investigations showed that, when the data of radiation, temperature and wind changed by 5% and 10%, the radiation was more effective than other parameters. Therefore to calculate the short wave radiation, radiation models of Angstrom, Sabbagh, Gelever-Mc Culoch and Black have been used. Calibration of obtained results with data of three weighting microlysimeter during the growing season (May to October) duration 95 days by using different statistical parameter such as coefficient of determination (R2), Root mean square error (RMSE), Mean bios error (MBE) and t-test criteria of 0.781, 0.625, 0.038 and 0.468 respectively, indicated that PMF56 model with radiation models of Angstrom is the best model for estimation of reference evapotranspiration and the models of JH1 and PMFI have low exactness for this climate. The finding of the present research reveal that in all investigated evapotranspiration models, the models that used Angstrom radiation have high accuracy and radiation models of Sabbagh, Gelever-Mc Culoch and Black are in next orders.

Nowadays, solar energy as one of the most important sources of clean and free of damaging environmental effects energy are used in many cases including generation of electricity, heat and desalination of salt water. The purpose of this research is identification of high radiation areas as most suitable regions for these applications.To do this, cloudiness data of 120 synoptic stations were used to find the number of days with 0-2/8 cloudiness and calculate the average of monthly, seasonal and the annual of them over a period of 20 years (1989-2008). The statistical software of SPSS 16 was used to find the correlation equations of locations (latitude and altitude) with a mean seasonal (with R2 equal 0.81, 0.82 and 0.84 for spring, autumn and winter respectively) and annual number (with R2 equal 0.78) of days with low cloudiness. Finally by the method of interpolation Spline has been produced zoning maps of seasonal and annual high radiation areas of country. The investigation of average monthly amounts indicated that the most sunny days in April belonged to the BAFT, in May belonged to JASK, in June belonged MINAB, in July belonged to DEHLORAN, in August belonged MAHSHAHR, in September belonged BUSHEHR, in October belonged to KENARAK, in November and December belonged to CHABAHAR, in January and February belonged to SARAVAN and in March belonged to CHABAHAR. Also in seasonal scale the cities of KAHNUJ, AGHAJARI and CHABAHAR in spring, summer, and autumn & winter respectively were most high radiation regions of country during this period. The study also found that 89 stations of 120 stations that studied, over 1989- 2008 in more than 200 days of 365 days on the year (more than 55 percent on the year), had clear and sunny sky and therefore most areas of Iran have great ability to use renewable solar energy.

Kerman province due to special geographic features such as cross the desert and mountainous conditions has specific weather and climate variation and particularly good conditions for cultivation of crops and the garden. Considering the limited threshold of tolerance of plants to meteorological parameters, any abnormalities in these parameters including the occurrence of stress freezing and thaw cycles will be damage to agricultural production. In this research for locating freezing and thaw cycles in the Kerman province, the data of daily minimum and maximum temperatures of 9 synoptic stations was used over 20 statistic years (1989-2008). Also 4 distinct range of temperatures including: the minimum temperatures lesser and equal whit -2 and the maximum temperatures greater and equal whit 2 (A), the minimum temperatures lesser and equal whit -3 and the maximum temperatures greater and equal whit 3 (B), the minimum temperatures lesser and equal whit -4 and the maximum temperatures greater and equal whit 4 (C), the minimum temperatures lesser and equal whit -5 and the maximum temperatures greater and equal whit 5 (D), were presented. After data processing by a computer program into the FORTRAN space, the number of days with this phenomenon for each station was determined as monthly, seasonal and annual, also monthly and seasonal relative frequency are calculated and compared these values with the critical temperature of crops and garden plants, was identified risky areas on province. The investigation of annual graphs showed that Anar station has most days of freezing and thawing cycles during the year. Review of seasonal relative frequency offreezing and thaw cycles show that winter has the most abundance of this phenomenon than other seasons, and two city of Bam and Baft shows higher rate of freezing and thaw in this season. But despite of this topic, because of cold acclimation phenomenon, cold-season cereals and fruit trees have less damage than spring and autumn seasons. Review of monthly results also showed that early planting (in April) fruit trees and crops such as wheat, barley, millet and cotton in the cities including Shahrebabak, Kerman, Kahnuj and Sirjan is risky, while in the cities of Baft, Bam and Jiroft, this plant will not face with damage. Also, since the abundance of this phenomenon in regions such as Shahrebababak, Sirjan and is better be accomplished autumn cultivation (in November and December) of this plants by using of resistant cultivars.

Freezing and thaw cycles that appear due to consistent decrease and increase of temperature in the short-term period are the important factors of damage to crop and garden plants in susceptible area. In this research to calculate the relative frequency of freezing and thaw cycles in the Khorasan Razavi province, the daily minimum and maximum temperatures of 9 synoptic stations were used over 20 statistic years (1989-2008). Also 6 distinct range of temperatures including: the minimum temperatures lower and equal to -2 and the maximum temperatures greater and equal to 2 (A), the minimum temperatures lower and equal to -3 and the maximum temperatures greater and equal to 3 (B), the minimum temperatures lower and equal to -5 and the maximum temperatures greater and equal to 5 (C), the minimum temperatures equal to -2 and the maximum temperatures greater than 2 (D), the minimum temperatures equal to -3 and the maximum temperatures greater than 3 (E) and the minimum temperatures equal to -5 and the maximum temperatures greater than 5 were presented. Following processing by a computer program in the FORTRAN space, the averages of monthly, seasonal and annual number of days with this phenomenon were calculated for each station and then the relative frequencies of monthly and seasonal were obtained. Results showed that, relative frequency of freezing and thaw cycles in winter is highest, but cold-season cereals and fruit trees show lower damage than spring and autumn seasons, because of cold acclimation phenomenon in this season. Monthly investigation showed that in October, the probability of damage to crop plants such as cotton or sugar beet in regions such as Sabzevar, Gonabad and Kashmar is less than regions such as Mashhad, Sarakhs and Neyshabur. In March and April, fruit trees may have faced with damage in Neyshabur, Torbat heydariye and Golmakan. Also in these months, early implant of cotton is risky in regions such as Sabzevar, Kashmar and Neyshabur.

Consistent decreasing and increasing of temperature in the short-term period that is called freezing and thaw cycles is one of the important factors of damage to crop productions. In this research as to determine freezing and thaw cycles in the Khorasan Razavi province, the data of daily minimum and maximum temperatures of 9 synoptic stations was used over 20 statistic years (1989-2008). Also 6 distinct range of temperatures including: the minimum temperatures lesser and equal whit -2 and the maximum temperatures greater and equal whit 2 (A), the minimum temperatures lesser and equal whit -3 and the maximum temperatures greater and equal whit 3 (B), the minimum temperatures lesser and equal whit -5 and the maximum temperatures greater and equal whit 5 (C), the minimum temperatures equal whit -2 and the maximum temperatures greater than 2 (D), the minimum temperatures equal whit -3 and the maximum temperatures greater than 3 (E) and the minimum temperatures equal whit -5 and the maximum temperatures greater than 5 were presented. After data processing by a computer program into the FORTRAN space, the number of days with this phenomenon for each station was determinated as monthly, seasonal and annual and then the mapping plans of susceptible areas were prepared. The results show that winter has a higher rate of this phenomenon and autumn and spring are next respectively. Also the investigation of mapping plans indicated that in most temperature ranges, the Torbat heydariye, Nishaboor and Ghuchan stations had maximum number of freezing and thaw cycles in Khorasan Razavi province. The minimum rate of this phenomenon was in the Sarakhs, Kashmar and Sabzevar Stations as well.

The solar radiation received by earth surface is one of the most applicable parameter that is so important in hydrology, agriculture, Meteorology and climatological modeling. Because of very expensive instrument for measuring the radiation, researchers suggested many different experimental equations to estimate this parameter in different climate. Seven models which are calibrated for semi-arid climate of Mashhad were used to find the optimum model for this area. These models are Angstrom–Prescott suggested by FAO, calibrated model of Angstrom–Prescott by Khalili and Rezaei Sadr (1 and 2), calibrated model of Angstrom–Prescott by Alizadeh and Khalili, Linear Regression Model of Alizadeh and Khalili, Sabbagh model and Glover and McCuloch. Results show that in daily scale the calibrated model of Angstrom–Prescott by Khalili and Rezaei Sadr including atmospheric water vapor spectrum is the best model in Mashhad’s climate where، ، and. Also in this scale, the calibrated model of Angstrom–Prescott by Khalili and Rezaei Sadr and Linear Regression Model of Alizadeh and Khalili are in the second and third order respectively. It is also found that in the monthly scale, the Glover and McCuloch model is the best one where، ، and