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Showing 61 results for Climate
Farzad Shirzad, Mr Bohlol Alijani, Mehry Akbary, Mohammad Saligheh,
Volume 0, Issue 0 (3-1921)
Volume 0, Issue 0 (3-1921)
Abstract
Climate change and global warming are very important issues of the present century. Climate change process, especially temperature and precipitation changes, the most important issue is environmental science. Climate change means a change in the long-term average. Iran is located in the subtropical high pressure zone in arid and semi-arid regions and the Hyrcanian forest is a green area between the Caspian Sea and the Alborz mountain range. At the 43rd UNESCO Summit, the Hyrcanian forests were registered as the second natural heritage of Iran. Beech is one of the most important tree species and the most industrial species of Hyrcanian forests It accounts for about 18 percent of the northern forest volume (from Astara to Gorgan with a life span of about 250 years). The study area is located in the Shanderman basin in western Guilan province. In this research using tree dendroclimatology, Use of vegetative width of beech tree rings, Weather station statistics located in the study area, And Mann-Kendall nonparametric statistical method, To Investigate Climate Change Trend on Growth Time Series and Pearson Statistical Method, in order to evaluate the correlation of diameter growth of beech tree rings with climate variables in the region, an attempt was made. Results of time series of beech tree growth rings over 202 years. Using the nonparametric method Mann- Kendall showed, Changes in growth rings of beech trees have a downward and negative trend, at level 5 %, it was significant. Temperature Minimum, Average, Maximum, and Evaporation during the growing season, there was an upward trend and Annual precipitation there was a downward trend. Using the Pearson method Fit correlation of growth ring diameter with temperature, For the average monthly in February and the average minimum temperature in July, August and September and Negative correlation, for average maximum temperature in February, July, August and September at 95% level, it was significant and precipitation in June, the correlation was 95% positive and significant.
Mahnaz Sadeghi, Zahra Haejazi Zade, Mohhamad Saligeh,
Volume 0, Issue 0 (3-1921)
Volume 0, Issue 0 (3-1921)
Abstract
The purpose of this study is to increase awareness and flexibility towards climate change and its effects on the environment through education. In the first step, to achieve the reproduction of climatic data and compare the scenarios of the general circulation model of the atmosphere, three important climatic parameters including precipitation, minimum temperature and maximum temperature were used and also SDSM software was used to predict the data. In this study, two stations of Zabol and Chabahar were used during the statistical period of 1961-2005. Three scenarios of RCP2.6, RCP4.5 and RCP8.5 in the period 2020-2050 were used to compare the results of the CanESM2 general circulation model, which is mentioned in the fifth IPCC report. The results of CanESM2 model showed that the minimum and maximum temperature and precipitation in the studied stations will have an increasing and decreasing trend in the future, respectively, in other words, the effects of climate change will be more obvious. In the second step, a questionnaire was distributed to teachers and students in Zabol and Chabahar in the education department; The results of validation of Cronbach's alpha test indicate that this questionnaire had good validity and reliability. The selection of the statistical population was purposeful; That is, from all the related schools, schools were purposefully selected at the discretion of the professors and were also evaluated and questioned. Analysis of the results of questionnaires related to teachers and students showed that the research hypothesis was confirmed according to T-Test.
Moslem Seydi, Kamal Omidvar, Gholamali Mozafari, Ahmad Mazidi,
Volume 0, Issue 0 (3-1921)
Volume 0, Issue 0 (3-1921)
Abstract
Abstract
Climate change is an important environmental issue because the melting processes of glaciers and snow density are sensitive to climate change. Today, a variety of satellite sensors such as AVHRR, MODIS, GEOS, MERIS are available for snow monitoring and are widely used to investigate and investigate the fluctuations and changes in snow cover globally. Modis sensor has been considered more because of its global spatial coverage with suitable spatial accuracy and frequent temporal coverage on different scales , Therefore, in the present study, snow products of this sensor were used. In this study, after collecting statistics and data on snow-related days during the statistical period (1989-2018) in three provinces of Kermanshah, Ilam and Lorestan, they were processed using Modis snow cover data in middle Zagros as well as remote sensing techniques, Finally, the snow cover changes in the study area were studied in detail. NDSI index was used in MODIS sensor products to detect snow cover. Consequently, in order to differentiate pixels and identify different phenomena, the received images were processed in GIS environment. . Investigation of snow cover changes in different seasons using Modis sensor images shows that most of the studied area has a significant decreasing trend, especially in the elevated areas of the study area And only in the western and southwestern regions of the study area, there is no specific decreasing trend. Also, the study of snow covered days during the study period indicates a decrease in middle Zagros snow cover and these changes have been intensified in recent years, especially in snow-covered areas of the region. Also, changes in winter and snow-capped and elevated areas were more and more severe than other seasons and other regions in the study area.
Miss Tara Heidari Orojloo, Dr Afshin Afshin Ghorbani Param, Dr Faramrz Hasanpour,
Volume 0, Issue 0 (3-1921)
Volume 0, Issue 0 (3-1921)
Abstract
The climatic conditions of each region of Iran are important parameters in the design and provision of thermal comfort in the design of housing. The purpose of this study is to provide appropriate models of climate design in Shiraz according to thermal comfort indicators. The research method in terms of descriptive-analytical nature and using modeling software (simulation) will be powerful Grasshopper software and is based on applied purpose. Climatic elements of Shiraz city in Ladybug plugin, download epw file of Shiraz city has been extracted from this method and in Ladybug plugin has been used for the simulation process. Then, using software to extract climate tables, diagrams of flowerbeds, and solar conveyors for optimal orientation for buildings, psychrometric diagrams were extracted to achieve the best design solutions compatible with the climate. The results of the research shows. The city of Shiraz in winter and spring, in the climate comfort zone and this situation is the same in February, March, and April, ie in terms of the temperature of these months (except 13 to 16 April) outside the climate comfort range Is located. ; In addition to placing most of the windows on the south side, the use of auxiliary heating equipment is also necessary. In June, July, August, and September, it is above the comfort level, so in addition to materials with high thermal mass, suitable canopies, as well as the use of a water cooler can bring the conditions inside the building closer to the comfort range.
Hassan Heidari, Ebrahim Mesgari,
Volume 0, Issue 0 (3-1921)
Volume 0, Issue 0 (3-1921)
Abstract
Understanding the daily weather types of any place location plays an important role in identifying its long-term climate. In this study, we employed the Wos classification method, along with a comprehensive climatology approach, to examine key variables such as minimum, average, and maximum temperatures, as well as cloud cover and daily precipitation. Data spanning from 1985 to 2021 were collected from 39 synoptic stations that had a good distribution in the country and had complete statistics, and weather types were identified using coding techniques. The findings revealed that the predominant temperature types in the country are predominantly hot and very hot, with sub-codes indicating generally low to moderate cloud cover and no precipitation. Moreover, the utilization of Ward's clustering method enabled us to identify three distinct climatic groups. The geographical characteristics of each place, such as location, altitude, latitude, proximity to the sea, and synoptic characteristics based on their influence, have the most important effect on the regional separation of groups in the country. The results of this research can be used to determine the weather calendar of each region during different time periods in many fields of agriculture, tourism, etc.
Esmaeail Ahmadi, Zahra Hejazizadeh, Bohlol Alijani, Mohammad Saligheh, Hassan Danaie Fard,
Volume 15, Issue 36 (6-2015)
Volume 15, Issue 36 (6-2015)
Abstract
The more exposure to Climate change / variability, the more vulnerability and a community with low adaptive capacity and high sensitivity is more vulnerable. Vulnerability reduction depends on adaptation policy and strategies. Designing and assessing these strategies require climate vulnerability (CV) measuring. To produce a new CV index, as a main propose of this study, first: The score of exposure factor for two five span years was calculated based on four synoptic stations data (Zabol, Zahedan, Iranshahr and Chabahar). Second: The scores of adaptive capacity and climate sensitivity were determined using all of the country census and yearbook data for 1385 and 1390. Third: Due to the nature and factors of vulnerability, a climate vulnerability index was developed based on the multiplicative-exponential model (CVIMEM). Forth: The index was calculated for the province and sub regions. The result shows, although the Sistan and Baluchistan (SB) adaptation capacity was increased, but because of the increased exposure and sensitivity, this province is 16.3% more vulnerable. Area with very high vulnerability label expanded from 57.5% to 100%, which reflects the spatial expansion of vulnerability over SB. The overall result is that vulnerability reduction needs for accurate and continuous measurement, on the increase adaptation capacity and mitigate climate sensitivity.
Hakimeh Behboudi, Mohammad Saligheh, Ali Bayat, Akram Zakeri, Fatemeh Jamali,
Volume 15, Issue 36 (6-2015)
Volume 15, Issue 36 (6-2015)
Abstract
Understanding weather zoning and knowing homogeneous climate regions are essential for land use and regional planning. The aim of this study was to compare three different geographical climate of Iran, the Caspian coastal, mountainous and arid interior of the provinces of Mazandaran, Semnan, Tehran, Qazvin, Qom, and Markazi. In order to do this study, climatic data of 56 synoptic and climatology stations and 19 climatic elements were used by using cluster analysis and factor analysis models. For this purpose, a matrix with dimensions of 56 x 19 and the R configuration and as a database was used for segmentation. By applying factor analysis based on principal components analysis with Varimax orthogonal rotation it was determined that in the climate of these three regions, four factors of humidity, temperature, dust and thunderstorms are affecting more than 85% of the total variance of the climate of this region. The hierarchical cluster analysis method and integration into the matrix of factor scores, four main and several sub-region areas were identified.The main areas are hot, dry desert area, low rainfall mountain slopes, the mountainous and cold and semi-rainy regions and high rainfall and finally the moderate high rainfall. The study of four areas and their local and regional conditions shows that the neighborhood with humidity source such as the Caspian Sea and rough configurations such Alborz Mountains play a decisive role in the formation of north sub-areas.
Yosouf Ghavidel Rahimi, Manochehr Farajzadeh, Mehdi Alijahan,
Volume 15, Issue 36 (6-2015)
Volume 15, Issue 36 (6-2015)
Abstract
Global warming and the meaningful relationship between temperature and precipitation changes over different areas of the earth with temperature increment of the earth, are considered as the most important patterns of this century’s climate changes. Today, there is debate over climate change and global temperatures increasing. Damaging effects of this phenomenon on the planet is one of the most challenging issues in global scale. Because of this, the research ahead is done for the detection of global warming on maximum temperatures, monthly and periodic (hot and cold) as well. For this study, two groups of data, temperature data of 17 synoptic stations and corresponding amounts of data in global temperature anomalies were figured out over 60 years period of time (1951 to 2010). Goals, the Pearson correlation method for detecting relationships between data's, linear and polynomial regression for trend analysis time series data , To illustrate the correlation between the spatial distribution of temperature data with global warming stations nationwide Geostatistical model Finally, non-parametric test for detecting significant temperature change Man - Kendall were used. According to the results impact of global warming on the maximum temperature in the cold months like January, December and November should be much lower, and the highest in spring and summer season in the southern stations such as Abadan, Ahwaz and Shiraz seen. The above process is also evident in periods of hot and cold temperatures and the influence of the stations temperature of the warm period of global warming were higher than cold period and represent an increase in the temperature of the warm period of years. In between, the number of stations as well as Anzali, Urmia and Khorramabad stations in some months had the opposite influence of global warming and seen drop in the maximum temperatures of them. It is also observed in the results obtained from the analysis period. Station's maximum temperature trend change is represents significant in the summer month. Changes trend in the months of July, August and September, is significant that the process is more pronounced in the southern stations. Significant analysis trend changes have been taken in periods (cold and hot) in studied stations indicative of its significance in warm period.
Zahra Hejazizadeh, Parisa Sadat Ashofteh, Ebrahim Fatahi, Zahra Gholampour,
Volume 15, Issue 38 (4-2015)
Volume 15, Issue 38 (4-2015)
Abstract
Abstract
In this study, the predicted monthly temperature and rainfall data from HadCM3 model (base period, ۱۹۷۲-۲۰۰۱) and next period (۲۰۱۱-۲۰۴۰) under A2emission scenario were used to investigate the impacts of climate change on runoff variations in the Kor river basin. HadCM3 model output was downscaled based on a temporal downscaling approach (Change Factor) and spatial downscaling approach (Proportional) for the basin. The time series of monthly temperature and precipitation were produced in future period. The results showed that temperature and rainfall will increase and decrease in the future period relative to the base period, respectively. Then, the calibrated IHACRES model was used to model rainfall-runoff relationships in the Kor river basin. Then, the downscaled monthly temperature and rainfall time series in next period were employed to rainfall-runoff model and the monthly runoff time series were simulated for period ۲۰۱۱- ۲۰۴۰. The comparison of future period runoff relative to observed period showed that the annual runoff in the basin for period ۲۰۱۱-۲۰۴۰ will decrease about ۹٫۴۳% with respect to base period.
Yousouf Ghavidel Rahimi, Manochehr Farajzadeh Asl, Solmaz Motalebizad,
Volume 16, Issue 40 (3-2016)
Volume 16, Issue 40 (3-2016)
Abstract
This study tries to identify, classify, and analyze synoptic cold wave in North West region of Iran. This study applies standardized (z scores) index of Minimum Temperature in the period of 1951-2010.as such cold waves were classified based on the intensity of occurance. Out of occured cold wave in North West of the coldest identified wave pertaingt each class for synoptic analyzes were selected. This study suggests that the prevailing pressure pattern during the relevant wave indicates high pressure over the earth surface as well as deep trough in upper layer. From the continuing cold standpoint, the role of changing position from pavallel wind in to meridional corresponel to blocking is very offective. Blocking in turn leads to reduction in speed of cold air masses which are originating from higher latitude. They were assouclated with cold waves. More precipitation as so ciated with higher latitude as well as low speed flows will lead to strong and continious waves.
Abasali Arvin, Abdolazim Ghangherme, Davar Hajipour, Mehran Hidari,
Volume 16, Issue 41 (6-2016)
Volume 16, Issue 41 (6-2016)
Abstract
In this study, by using the Mann-Kendall nonparametric method and Sen' s Estimator slope test, the trend of some elements including precipitation, average of maximum and minimum temperature and the number of snowy days Chaharmahal and Bakhtiari Province covers part of Zagros and Zardkohe-Bakhtiari highlands, from which three major rivers including Zayandehrud, Dez and Karun originate. in an annual and monthly scale, was evaluated in the stations of the province during a period of 30 years (1986-2015). The output was presented in the form of tables, graphs and iso-trend maps as drawn in the Arc_GIS. The results showed that although changes in rainfall did not follow any specific trend in most months of the year, the amount of precipitation in the stations of Koohrang as the rainiest station in the Province, Lordegan and Yan-Cheshme had a decreasing trend at the significance level of 99%; also, the the number of snowy days during March showed a decreasing trend in Koohrang station. However, the average minimum and maximum temperature in most areas of the province, in both monthly and yearly scales, except for the months of November and December, had a significantly increasing trend.
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Volume 16, Issue 42 (9-2016)
Volume 16, Issue 42 (9-2016)
Abstract
This study aimed to evaluate the climatic conditions for the establishment of Borujerd city in the design of buildings and streets of the city with an emphasis on radiant energy, an attempt to reduce problems related to cold climate is that in order to achieve this goal of data synoptic station in the city of Boroujerd a period of 23 years, including temperature, precipitation, relative humidity and other parameters as maximum, minimum and average is used. This study is cross-sectional study and extensive research studies of all documents related to the concept and the; and the method of data collection in the expression of the status quo and in Analysis of the types of library issues Bamtalh documents, and field research. The main tools of analysis in this study include Oleg bioclimatic models, Gioni and computational methods is the law of cosines In this respect, first using data from synoptic weather station borujerd in chart eco building and open spaces and drawing on its,thresholds and thermal requirements of the building inside and outside and then priorities for the design and construction of climate , urban streets is determined;The results showed that , best orientation for settlement building in Borujerd in order to optimize the energy consumption is south- north after15 west.and best orientation for streets plan in Borujerd according the AS interaction is toward southwest- northeast and after that 60 west in order to avoid permanent ice and snow.
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Kamal Omidvar, Reza Ebrahimi, Mohammad Kykhsrvy Kayani, Ghasem Lkzashkoor,
Volume 16, Issue 43 (12-2016)
Volume 16, Issue 43 (12-2016)
Abstract
The aim of this study was to investigate the effects of global warming on where the slope changes when the monthly temperature in Iranian territory over the coming decades (2050-2015). The simulated temperature dynamic model EH5OM subset Hybrid Models atmospheric circulations (GCM) selection and data model of the Center for Theoretical Physics Salam (Italy) were derived from emission scenarios A1B scenario was chosen given the scenario of 2100 -2001 found that from 2050 to 2015 were used in this study data is then output the data in the fourth edition of the regional climate model (RegCM4) Linux environment was fine scale output data Downscaling model with dimensions of 27/0 * 27 / Degrees latitude is where the dimensions of 30 x 30 km area of approximately cover the average temperature of the matrix deals 13140 2140 * was extracted. Finally, the slope of the average monthly temperature during the period under study by Mann-Kendall slope age and matrix computation in MATLAB software 13140 * 12 respectively. Results show rising temperatures in March and April to June, more than 90% of the country, that it will be spring's warmer. Increasing the temperature in the winter months and spring mountainous parts of the western half of the country is warming the cold regions of Iran. Temperature negative trend in October and November in the northern part of the eastern half of the region's countries could be indicative of colder temperatures in the northern West.
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Volume 17, Issue 46 (9-2017)
Volume 17, Issue 46 (9-2017)
Abstract
Since the most important climatic parameter affecting sugar beet cultivation is the temperature, we carried out this research considering climatic elements such as temperature, precipitation and freezing days in relation to autumn sugar beet planting. Daily temperatures of selected stations in a period of 10 years (2005-2015) has been used for agroclimatic analysis. In order to evaluate that, thermal potential assessment, deviation from optimal conditions and active day gradient index (GDD) were used. The evaluation of thermal potential based on the threshold of 0, 4, and 10 degrees Centigrade at the station levels in Kermanshah province showed that Sar-e-Pol-e-Zahab Station has the highest cumulative thermal unit and Kangavar Station has the least one. In Isfahan province, Khour-va-Biabanak station has the highest cumulative thermal unit and Khansar station has the lowest unit. Based on the deviation from optimal conditions in Kermanshah province, Sar-e-Pol-e-Zahab station has the lowest (-27.79) and in Khour-va-Biabanak station (-21.78) had the least deviation from optimal conditions. Planting date at the stations was considered based on the autumn temperature. In Kermanshah province, Sar-e-Pol-e Zahab station had the earliest date of harvest (May 1st.), while this date in Isfahan province was for Khour-va-Biabanak station (May 9th.). Suitable areas for planting in Kermanshah province are found to be the eastern and northeastern regions of Sar-e-Pol-e Zahab and Qasr-Shirin. In the province of Isfahan, the northern and western parts of Khour-va-Biabanak and Kashan were the most proper regions and central areas are in the next steps.
Dr. Morad Kavianirad, Dr Yadollah Karimi Pour, Dr. Hedayat Fahmi, Mr. Sadegh Karami,
Volume 17, Issue 46 (9-2017)
Volume 17, Issue 46 (9-2017)
Abstract
Efforts to provide security have always been of great importance to human being. In recent decades, the security issues of climate change have attracted attentions due to its sustainable consequences on the lives and civilization of humans. Among all countries, the ones which are placed in draught belt, like our country Iran, have hurt a lot because of low precipitations and also mismanagements in water resources control. Climate change show itself by changes in precipitation patterns, reduction of precipitation and increasing of temperature. According to the present data, Iran's central drainage basin which consists of important geopolitical provinces, has been affected by the above mentioned factors. This descriptive-analytic research is carried out based on the effects of climate change on Iran's central basin which provides approximately 48 percent of Iran’s GDP. Continuity of climate changes in this region can make critical problems in social, environmental, economic and political scales and the lives of the citizens would be affected as well. To conclude, the persistence of the current conditions in climate change in the central drainage basin of Iran, would result in challenges through the national stability and security.
Alimohammad Khorshiddoust, Behrooz Sarraf, Bagher Ghermez Cheshmeh, Mrs Fatemeh Jafarzadeh,
Volume 17, Issue 47 (12-2017)
Volume 17, Issue 47 (12-2017)
Abstract
In recent years, the severe fluctuations in precipitation have affected various parts of the country. On the southern coasts of the Caspian Sea, precipitation as one of the important climatic parameters has undergone changes due to global climate change. In the present study, we tried to evaluate the effect of climate change on rainfall in this region by applying a suitable model. In this study, observational period rainfall (1961-2001) was analyzed. the output of the HadCM3 model was used. At first, seven synoptic stations were selected and their data were analyzed in terms of accuracy, and length of statistical period, and lost data was restored. The AOGCM data were simulated using the SDSM model and the rainfall values were simulated for the observation period. After confirming the matching of the simulated data with observational data, the values of the Future (2039-2011) is estimated. The estimation errors of the SDSM model were calculated monthly by MBE and MAE criteria, and then compared. The output of the SDSM model was used to study the total annual precipitation in days with rainfall of more than 1 mm in the observation period and the upcoming period (2011-2039) by the R-Climdex model and the values of the PRCPTOT index Became zoning in the Future. The results showed that the model error in season with high rainfall is more than seasons with low rainfall. On a monthly scale, the maximum error occurred in the months of September, October, November and December. The maximum error in the fall and the minimum error was calculated in the spring and April and May months. According to the results, the total annual rainfall in the period of 2039-2011 will decrease in Anzali, Babolsar, Gorgan and Noshahr stations and rainfall will increase in stations of Astara, Ramsar and Rasht. Geographical distribution of selected were 5 sites in the Khuzestan, 20 sites in Bushehr, 24 sites in Hormozghan and 12 sites in Sistan and Baluchistan provinces. In total, 9000 sites were selected with a 2 km2 were suitable for large scale microalgae cultivation. The total area of these sites were estimated to be 18000 km2. The highest number of proper sites were found in Hormozghan province and lowest numbers of sites were found in Khuzestan province. The availability of technical service, carbon dioxide point resources from oil and gas units are an advantages for microalgae related activities in the Bushehr and Khuzestan provinces. The higher quality of water in the Sistan and Baluchistan province is an advantages for development of microalgae biomass production in the area.
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Volume 17, Issue 47 (12-2017)
Volume 17, Issue 47 (12-2017)
Abstract
The purpose of this research is the simulation of the maize function to scenario of climate change to the present and future. So to survey the region climate, daily data, maximum and minimum temperature, precipitation and radiation have been utilized during the period of (1987-2016). In order to simulating of climate in future, firstly the date of IPCM4 model under scenario and 30’s and 50’s with downscaling LARS-WG model. Before the simulation yield of maize, APSIM model was evaluated and validated. To calculate the maize yield the output of LARS model, plant date and were utilized as the cropping input model of APSIM. By variance analysis maize yield was compared in present and future. The results showed that the APSIM model validation can simulate acceptable accuracy and climate parameters change effect on the yield rate of maize. And on the basis of the highest yield in Fasa the lowest in the city Abade in base line. In future under different scenarios of climate change, maze grain yield in Fars province except Abade, other cities are decreasing than base line.
Dr. Mostafa Karimi, Mis Fatemeh Sotoudeh, Dr. Somayeh Rafati,
Volume 18, Issue 48 (3-2018)
Volume 18, Issue 48 (3-2018)
Abstract
Increasing CO2 emissions and consequently, air temperature causes climate anomalies which affects all the aspects of human life. The purpose of this study was to assess the temperature changes and also to predict the extreme temperatures in Gilan and Mazandaran Provinces. To do this, the SDSM statistical and dynamical model was used. As well, it was applied the Mann-Kendal graphical and statistical technique to analyze the temperature changes and its trend. In this regard, the daily temperature was obtained from Rasht, Ramsar and Babolsar synoptic stations during 1961 – 2010, and also the general circulation models data of HadCM3 and NCEP were collected from related databases. The results revealed a significant positive trend in monthly and annual minimum and maximum temperature in all three stations in the first (1961-2010) and third (1961-2040) periods. There is not a significant trend in extreme temperatures in Ramsar and maximum temperature in Rasht in the second period (2011-2040). The Mann-Kendal graphical test was used for the yearly extreme temperatures in all periods. The results showed that it was occurred both increasing trend and suddenly changes or shifts at the 95% confidence level in all stations. It is occurred the highest of changes in monthly and annual of the minimum temperature at forecasted period (2011-2040). It was predicted extreme temperature to increase about 0.1 to 1.7° C. The short time oscillations and significant positive trend occurred in both the maximum and minimum temperature shows the temperature increase and climate changes in the future. Thus it is obvious the decrease in temperature difference in warm and cold seasons.
Naseh Qaderi, Bohloul Alijani, Zahra Hejazizadeh, Mohammad Saligheh,
Volume 18, Issue 48 (3-2018)
Volume 18, Issue 48 (3-2018)
Abstract
Wheat is the main focus of the economy of Kurdistan province in which the annual fluctuation of wheat yield is 4/11 times as affected by the climatic elements of the site. This study investigated the role of agro-climatic variables and indices on rainfed wheat yield in Kurdistan province. The data of planting area, amount of production, damages and yield of wheat of 31-year in 10 regions of Kurdistan along with the hourly, daily, decade, monthly, seasonal and yearly levels data of 22 synoptic stations were collected. The correlation between wheat yield and 128 independent variables was calculated. The effect of variables on yield evaluated by multivariate regression. The spatial analysis of variables was performed and the spatial model of wheat yield was introduced for province and regions. The results showed that climatic elements in various regions are different, in a 99% confidence. Most of the independent variables alone have a significant effect on wheat yield, but in the stepwise model, 7 variables such as: the number of rainy days of the year, the sum of the degree hours (of temperature less than -11 ° C) in germination and tilling stage, annual precipitation and the precipitation of November are determinants of the yield. Yield and effective independent variables have significant spatial differences even in a cluster climate type. The highest and lowest coefficient of variation of wheat yield is related to Bijar and Kamyaran areas, respectively. Kamyaran and Sanandaj regions have the highest and lowest yield, respectively. Bijar is the highest risk region of the province for wheat production.
The results of this study showed that with a 99 percent confidence, climatic elements (variables) vary in different regions. Most of the independent variables have a significant effect on wheat yield in simple linear regression, but in Stepwise method, due to the internal correlation between variables, just variables entered that have insignificant correlation with each other and have more effects than other variables. The variables affecting the performance are differentin various regions, and from the point of view of effectiveness, the arrangement of the variables in different areas vary too. In other words, even in two regions with a climatic type (based on the Modified De Martonne method), both agro-climatic indices and wheat yield are significantly different. The impact of effective variables on yield at any time and place depends on the time of year and the phonological stage of wheat. At one time the environmental conditions of different regions in terms of temperature, humidity and precipitation differ, based on phonological stages of the regions. The time of the vulnerability of wheat varies from place to place. Wheat vulnerability at flowering stage is more than other stages. The effect of independent variables on yield at different times of year is proportional to the phonological stage in years Different and different in different regions. In Kurdistan province, the number of rainy days of the year, total degree hours the temperature reaches below -11 °C (sum of hours with below -11 °C temperature) from germination to tillering stage, the annual precipitation, the rainfall in the fifth decade of the water year (the precipitation of 11-20 of November), annual relative humidity and total degree hours the temperature reaches above 30°Ctemperature (sum of hours with above 30 °C temperature) in milky and dough stage is the determinants of the production of rainfed wheat. In Baneh and Marivan areas, the coefficient of variation (CV) is lower and in Bijar and Divandareh regions CV is more than other regions. Kamyaran region has the highest yield, Baneh and Marivan were ranked secondjointly. Sanandaj and then Bijarhave the lowest yield. Each region has a model for wheat yield and determinant factors vary from region to region. Although the annual production of Bijar is higher than other areas, wheat production in the Bijar region has a higher risk than other areas.
The results of this study showed that with a 99 percent confidence, climatic elements (variables) vary in different regions. Most of the independent variables have a significant effect on wheat yield in simple linear regression, but in Stepwise method, due to the internal correlation between variables, just variables entered that have insignificant correlation with each other and have more effects than other variables. The variables affecting the performance are differentin various regions, and from the point of view of effectiveness, the arrangement of the variables in different areas vary too. In other words, even in two regions with a climatic type (based on the Modified De Martonne method), both agro-climatic indices and wheat yield are significantly different. The impact of effective variables on yield at any time and place depends on the time of year and the phonological stage of wheat. At one time the environmental conditions of different regions in terms of temperature, humidity and precipitation differ, based on phonological stages of the regions. The time of the vulnerability of wheat varies from place to place. Wheat vulnerability at flowering stage is more than other stages. The effect of independent variables on yield at different times of year is proportional to the phonological stage in years Different and different in different regions. In Kurdistan province, the number of rainy days of the year, total degree hours the temperature reaches below -11 °C (sum of hours with below -11 °C temperature) from germination to tillering stage, the annual precipitation, the rainfall in the fifth decade of the water year (the precipitation of 11-20 of November), annual relative humidity and total degree hours the temperature reaches above 30°Ctemperature (sum of hours with above 30 °C temperature) in milky and dough stage is the determinants of the production of rainfed wheat. In Baneh and Marivan areas, the coefficient of variation (CV) is lower and in Bijar and Divandareh regions CV is more than other regions. Kamyaran region has the highest yield, Baneh and Marivan were ranked secondjointly. Sanandaj and then Bijarhave the lowest yield. Each region has a model for wheat yield and determinant factors vary from region to region. Although the annual production of Bijar is higher than other areas, wheat production in the Bijar region has a higher risk than other areas.
Zahra Sadat Hoseini, Shahriar Khaledi, Abdolmajid Naderi Bani,
Volume 18, Issue 49 (3-2018)
Volume 18, Issue 49 (3-2018)
Abstract
Paleo-climate reconstructions based on multi-proxy such as sedimentology is current in climatology investigation. In this way, National Institute of Oceanography and Atmospheric Science cored 960cm from Arzhan wetland SW of Iran than we have investigated of sedimentology. Primarily the core was measured on magnetic sensibility per 1cm and secondly was subsampled according to magnetic sensibility and were analyzed include TOC, CaCO3, and Grading laser and etc. Finally four samples of pace of plant were selected and have been dated in carbon 14 dating laboratory of Poznan, Poland, and calibrated trough of core based on Calib rev. 7.1. Dating have determined that core had covered 15000 Cal. BP. According to this investigation, we obtained 5 period of climate conditions during Pleistocene to Holocene in this area. 15000-13000 Cal. BP. Late Pleistocene climate conditions were colder and wetter period that indicate end of the Ace age. 13000-11000 Cal. BP. Climate begin to warmer and dryer. 11000-9000Cal.BP. because of this period shows many fluctuations in all proxies we named this period to the period of transfer from ace age to interglacial period. 9000-7000Cal. BP there have been warm and cold conditions compare to late Holocene. 7000- Present indeed in this period radiantly modern pattern of atmospheric circulation has been performed due to all of proxies in late Holocene begin to fixed on the same pattern. So probably atmospheric circulation from meddle Holocene begin to get harmonic to present. Any way for determinate of paleo-climate in this area we need to use of multi proxy investigation in area.
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