Climatology
Aliakbar Shamsipoor Shamsipoor; Seyfolah Kaki; Ayob Jafari; Seyd Maysam Jasemi
Volume 22, Issue 64 , September 2018, , Pages 149-167
Abstract
The aim of the research is recognizing mechanisms of the heavy rainfalls in the west and southwest of Iran using synoptic and thermodynamic method. For analysis of case study at April 2016, At first was obtained and calculated hourly rainfall data from 70 weather stations in the research area and 10 ...
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The aim of the research is recognizing mechanisms of the heavy rainfalls in the west and southwest of Iran using synoptic and thermodynamic method. For analysis of case study at April 2016, At first was obtained and calculated hourly rainfall data from 70 weather stations in the research area and 10 weather stations bordering the research area. Then rainfall amounts in stations were calculated and zoned using Arc/Map10. After that Ki, Li, TTi, Cape and SWEAT instability indexes was calculated for Kermanshah and Ahwaz weather stations. Finally, the synoptic maps were analyzed. According to instability indexes, mostly atmospheric instability has been moderate and favorable conditions could be observed for convection and thunder storm, lightening and snow fall. The analysis of the sea level synoptic maps have shown that a few days before the rainfall, the study area has been under the influence of the Siberian high, and simultaneously cyclones centers were formed above the Mediterranean Sea. Their eastern-ward movements created the condition for instability and rainfall in the area. Cold air downfall from high-pressure centers toward the backside of the Mediterranean trough and lower latitudes beside the dislocation of warm humid air to the fore side of the trough created the front and resulted in intensifying the rainy system that finally resulted in heavy rainfall in the area. The atmospheric physical and dynamic indexes show that during the rainfall, voracity positive values, jet stream wind and negative omega figures were in their maximum.
Climatology
Hossein Asakereh; Ali shahbaee kotenaee
Volume 22, Issue 64 , September 2018, , Pages 211-228
Abstract
Pervasive cold days are one of the abnormal continental events that have a lot of effects on environment and human activity. These events are created as a result of formation of complex atmospheric patterns. In these patterns, knowledge of how these atmospheric systems interact can be very useful in ...
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Pervasive cold days are one of the abnormal continental events that have a lot of effects on environment and human activity. These events are created as a result of formation of complex atmospheric patterns. In these patterns, knowledge of how these atmospheric systems interact can be very useful in prediction of the similar conditions and reduction the contingency damages. On this basis in this present research, it has been tried to analyze the earth's temperature conditions and dynamic and synoptic conditions of different levels of atmosphere on 21 January 1964 as pervasive cold day in Iran by using data from minimum temperature gained in different parts of the country and also the atmospheric data from 1960 to 2010. In this day 98.4 % of the area has been affected by the cold. The results of synoptic and dynamic analysis of atmospheric systems that creating the cold of this day showed that created a blocking system in west and center of Europe and establishment a low height system in north of Russia and the opposite movements of these two systems to each other has caused that cold polar air from northern Scandinavia have moved to Iran. It has also been recognized that height factor has performed an important role in cold extremity in this day across the country.
Climatology
Golam Abbas Fallah Galharei; mehdi asadi
Volume 22, Issue 64 , September 2018, , Pages 229-246
Abstract
This study aims to identify the spatial autocorrelation and spatial variation of sunshine hours in Iran. For this purpose, the sunshine hours to form a network database have been made in Iran. The data from the base of a 30-year period, the daily period from 1/01/1982 to 12/31/2012 AD to the present ...
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This study aims to identify the spatial autocorrelation and spatial variation of sunshine hours in Iran. For this purpose, the sunshine hours to form a network database have been made in Iran. The data from the base of a 30-year period, the daily period from 1/01/1982 to 12/31/2012 AD to the present study, and intercellular dimensions of 15 × 15 km area stretching is studied. In order to achieve the sunshine hourly changes within a year, the sunshine of the Iran of spatial statistical methods, such as spatial autocorrelation global Moran, Moran's index of local Insulin, and hot spots was used by using the programming environment GIS. The results of this study showed that the spatial and temporal variation in sunshine hours in Iran is High-cluster pattern. In the meantime, based on local Moran and hot spots, South, South East and Central synoptic stations representing the provinces of Sistan and Baluchistan, Kerman, Shiraz, Isfahan and Yazd have positive spatial autocorrelation pattern, full sun pattern, and parts of North, North East and North West representing synoptic stations in Tabriz, Mazandaran, Mashhad and Semnan have a negative spatial autocorrelation, low sun pattern. In the study period, in most cases, a large part of the Iran, almost half of the total area, has had no significant pattern or spatial autocorrelation
Climatology
hassan lashkari; Aliakbar Matkan; Majid Azadi; Zainab Mohamadi
Volume 22, Issue 64 , September 2018, , Pages 247-266
Abstract
As a result of Iran’s geographical position towards atmospheric general circulation, most of its area has an arid or semi-arid climate. In this research, the author has calculated precipitation start using the daily precipitation information obtained from 30 stations located in 8 southern and south-western ...
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As a result of Iran’s geographical position towards atmospheric general circulation, most of its area has an arid or semi-arid climate. In this research, the author has calculated precipitation start using the daily precipitation information obtained from 30 stations located in 8 southern and south-western provinces of Iran during a 36 year statistical period and of course, based on selected criteria. In ten years, precipitations have started sooner than normally expected. Entire up to 700 HPa levels and sea level pressure maps belonging to 1st of September till the day of precipitation start have been illustrated with Grads software using atmospheric data obtained from Ncep/ncar site. Results of several objective observations of maps manifest that early precipitations in south and south-west sides of Iran are generally occurred in three main patterns. Pattern A) as African sub-tropical high pressure passes above central Mediterranean in a northward move and its eastern trough integrates with migratory anticyclone (deployed on the north side of Caspian Sea), it provides the necessary context for cold advection to move towards north of African high pressure. Afterwards, the migratory anticyclone trough integrates with anticyclone ridge of Arabian high pressure and therefore a very suitable situation is provided for advection of moisture to move inside the Sudan low system. In pattern B) almost thirty days before start of precipitations, the Azour anticyclone adopts a northward movement.
Climatology
Kamran Zeinalzadeh; Neda Khanmohammadi
Abstract
Reference evapotranspiration (ET0) is one of the important factors to determine crop water requirement. Accurate estimation of reference evapotranspiration (ET0) value has a very important role in water resources management and optimizing agricultural water consumption. In other words, calculating the ...
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Reference evapotranspiration (ET0) is one of the important factors to determine crop water requirement. Accurate estimation of reference evapotranspiration (ET0) value has a very important role in water resources management and optimizing agricultural water consumption. In other words, calculating the accurate values of this parameter plays an important role in irrigation planning and consequently existent water resources management.
Climatology
amanollah fathnia; hamid rahimi; Shoaieb Abkharabat
Abstract
Siberian high pressure (SHP) is synoptic system that during the autumn and winter seasons on Asia is religious (Msaudian and Kaviani, 2009: 15). In the cold term of the year, the vast Siberian territory due to the clear sky and away from water sources, the more energy through the long wave radiation ...
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Siberian high pressure (SHP) is synoptic system that during the autumn and winter seasons on Asia is religious (Msaudian and Kaviani, 2009: 15). In the cold term of the year, the vast Siberian territory due to the clear sky and away from water sources, the more energy through the long wave radiation loses, thereupon the around air of land gradually adjacent to becomes cold high-pressure center.
Climatology
Yousef Ghavidel Rahimi; Manuchehr Farajzadeh; masood salehian
Abstract
Nowadays, Climate change is a hot topic engaging the scientists around the world as a cause for future human and environmental crises. It has been generally accepted that the main cause for climate change should be increases in the content of atmospheric carbon dioxide due to excessive burning of fossil ...
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Nowadays, Climate change is a hot topic engaging the scientists around the world as a cause for future human and environmental crises. It has been generally accepted that the main cause for climate change should be increases in the content of atmospheric carbon dioxide due to excessive burning of fossil fuels, esp. in industrial countries. In the 19th century, scientists realized that gases in the atmosphere cause a "greenhouse effect" which affects the planet's temperature. These scientists were interested chiefly in the possibility that a lower level of carbon dioxide gas might explain the ice ages of the distant past. At the turn of the century, Svante Arrhenius calculated that emissions from human industry might someday bring a global warming. Other scientists dismissed his idea as faulty. In 1938, G.S. Callendar argued that the level of carbon dioxide was climbing and raising global temperature, but most scientists found his arguments implausible. It was almost by chance that a few researchers in the 1950s discovered that global warming truly was possible. In the early 1960s, C.D. Keeling measured the level of carbon dioxide in the atmosphere: it was rising fast. Researchers began to take an interest, struggling to understand how the level of carbon dioxide had changed in the past, and how the level was influenced by chemical and biological forces. They found that the gas plays a crucial role in climate change, so that the rising level could gravely affect our future.
Climatology
Reza Mokarian; Hossein Sedghi; Samira Nemati; Hossein Babazadeh
Abstract
Evaporation is the important factor that affects temperature, drought severity and water storage in the hydrological cycle and plays an important role on managing the water resources projects such as agricultural irrigation. Classification of datasets is useful for concisely system modeling purposes. ...
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Evaporation is the important factor that affects temperature, drought severity and water storage in the hydrological cycle and plays an important role on managing the water resources projects such as agricultural irrigation. Classification of datasets is useful for concisely system modeling purposes. By classification, a large number of datasets is reduced to a small number of groups. In the field of hydrological systems, classification of meteorological stations into homogeneous groups will be useful to consider a different scale of measure, which is suitable to each group. Such classification can lead to choice methods appropriate for each group for management of water resources in various regions. Classification will also be useful for prediction of events such as droughts. Moreover, in the case of estimating missing data, the corresponding data of the representative station determined using a classification technique can be successfully substituted (Raju and Kumar 2007). stations. Dikbas et al. (2011) applied the FCM method to classify the precipitation series and identify the hydrologically homogeneous groups in Turkish. Regional homogeneity test results showed that regions determined by the FCM approach are sufficiently homogeneous for regional frequency analysis. In the present study, the practical applicability of two classification methods, namely fuzzy c-means (FCM) cluster analysis and Kohonen artificial neural networks (KANN), is examined for grouping 97 evaporation stations in Iran into homogeneous groups. The rest of the paper is organized as follows. First, a description of the case study is presented. After introducing the applied methods, results obtained are presented and discussed and conclusion drawn.
Climatology
Mahmoud Houshyar; Behrooz Sobhani; Seyed Asaad Hosseini
Abstract
With the seriousness of the climate change debate in the world, the study of parameters and elements of the climate has been widely considered. With changes in climate patterns and changes in temperature and precipitation patterns, other components such as runoff and soil moisture, which are important ...
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With the seriousness of the climate change debate in the world, the study of parameters and elements of the climate has been widely considered. With changes in climate patterns and changes in temperature and precipitation patterns, other components such as runoff and soil moisture, which are important for natural and human systems, will undergo metamorphosis. Therefore, long-term prediction of climatic variables has been considered by many scientific communities worldwide in order to know about their changes and considering the necessary measures to moderate the adverse effects of climate change. The phenomenon of climate change is of increasing importance due to its scientific and practical dimensions, since human systems dependent on climatic elements such as agriculture, industry and the like are designed and operated on the basis of the stability and stability of the climate. Accordingly, general circulation models (GCMs) have been developed. Although these models represent significant results on the atmospheric and continental spatial scales, they combine a large part of the complexity of the planet's system, but they are inherently unable to control the dynamics and forms with a fine grid Local scalability. Therefore, an assessment of the effect of climate change on a local scale requires an interim and spatial gap between large-scale climatic variables and meteorological variables with local scale, in which case the main approach is the same downscaling models. The SDSM model is one of the most widely used statistical microscopic instruments, which has many uses in meteorological, hydrological, geographic and environmental studies. Because in this method, large-scale daily circulation patterns are used on a stationary scale; and when used for the rapid and cost-effective estimation of climate change, and for randomized meteorological generators and modified functions, have given acceptable results. Given that global models have generally simulated climatic elements until the year 2100, it is possible to use global model data to simulate the desired variables such as precipitation and temperature on a station scale. The Intergovernmental Panel on Climate Change (IPCC) has used its latest assessment report (AR5) on new scenarios for the RCP as representatives of different levels of greenhouse gas emissions. The new emission scenarios have four key paths RCP2.6, RCP4.5, RCP6 and RCP8.5, which are named after their radiation in 2100, Future Perspective. The variation of the maximum temperatures of the synoptic station of Urmia during the period (2021-2050) of the CanESM2 global model has been used under three scenarios RCP2.6, RCP4.5 and RCP8.5.
Climatology
Saeid Jahanbaksh; Gholam Hasan Mohammadi; shahnaz rashedi; Atefeh Hoseini Sadr
Abstract
In this study, non-parametric Mann-Kendall test was used to analyze the trend of monthly mean minimum temperature in the Northwest of Iran. For this purpose, the data from 35 synoptic stations in the cold part of year including November, December and January-to-April have been used in the period of 24 ...
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In this study, non-parametric Mann-Kendall test was used to analyze the trend of monthly mean minimum temperature in the Northwest of Iran. For this purpose, the data from 35 synoptic stations in the cold part of year including November, December and January-to-April have been used in the period of 24 years (1987-2010). Kriging interpolation method was used to obtain spatial distribution of mean minimum temperature over study area. The results showed that the minimum temperature in most parts of study area is rising so that in the months of February, March and December respectively in 22, 19 and 17 stations of the 35 stations were determined an increasing trend. While only in April, at 6 weather stations decreased and this parameter is relatively stable in November and January. Spatial distribution of monthly mean minimum temperature indicated that this element is lower in the mountainous parts of study area (including Northwest and Southeast) and whiles in lowlands (including Northeast and Southwest parts), is higher than its regional average. It was also found that regional minimum temperature and its trend in the Northwest of Iran Does not have the same characteristics in different months, so that this parameter in January and in April increased and decreased in November and December. Finally, in November and December minimum temperature has not substantially changed.
Climatology
Hosein Rahmati; Samad Gholizadeh; Hosein Ansari
Abstract
Accurate estimation of watershed runoff has a crucial role in its management. Until now many researchers used different models such as integrated and distributed models, and also artificial intelligent methods to estimate basin runoff. For this purpose in this study for estimation the runoff of Bara-Ariye ...
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Accurate estimation of watershed runoff has a crucial role in its management. Until now many researchers used different models such as integrated and distributed models, and also artificial intelligent methods to estimate basin runoff. For this purpose in this study for estimation the runoff of Bara-Ariye basin with an area of 112 km2 and average annual rainfall of 306.72mm, two different models namely WetSpa and artificial neural network (ANN) were used. To run of the WetSpa model two categories of information, including raster maps and metrological data and for ANN model only meteorological data were used. The 5 years data were used to simulation runoff of Bara-Ariye basin. The statistical parameters such as correlation coefficient (R2), the square of the standard error of the mean (RMSE) and mean absolute error (MAE) were used for comparison results of two models. The results indicated that the WetSpa model with R2 and RMSE equal to 0.920 and 0.346 m3/s and also ANN model with R2 and RMSE equal to 0.959 and 0.310 m3/s have the ability to simulate runoff of Bara Ariye River. Also using neural network model reduced the error estimation of watershed runoff 11.6% compared with the WetSpa model.
Climatology
Ghasem Azizi; Nima Farid Mojtahedi; Faezeh shabanzadeh; Samaneh Negah; Hasan Abed
Abstract
In this research, effect of environmental forcing like topography, direction and sharpness of slope, shape and trend of topography on wind regime formation have been studied in mountainous stations of gilan. The regime of mountainous winds has major effects on the air conditions in mountain regions. ...
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In this research, effect of environmental forcing like topography, direction and sharpness of slope, shape and trend of topography on wind regime formation have been studied in mountainous stations of gilan. The regime of mountainous winds has major effects on the air conditions in mountain regions. This research had been done using hourly data of wind speed and wind direction and also analysis and fitness of topography conditions with theoretical fundamental of research. So it was observed that Masouleh station is one of the best mountains stations in the subject of mountains climatology. Suitable location of this station in the middle slope caused to affected region by upslope wind and down slope wind (katabatic and anabatic winds). Location of Deylaman station on southern slopes of Alborz Mountains had important effect on wind speed decreasing. Wind occurrence mechanism is Mountain wind type along vallay in Deylaman station. Secondary dominant wind was north-northwest thus daily and seasonal behaviors of wind and location of Caspian Sea and Alborz Mountain represent affecting the region by sea-land breeze system. Jirandeh station’s behavior is as an exclusive mountainous station that indicated deep combination but imperceptible influence of the mountain on atmospheric phenomena in Mountains range. Position of station on southern slope provided appropriate conditions to form slope wind occurrence in this region. However stretching of Totkabon- siahrood valley as a wide valley that is branching of sefidrood valley provided appropriate conditions to influx sea-breeze wind. This condition caused destruction of local mountain wind effects during day and night.
Climatology
masoud jalali; Vahab Kamariyan
Abstract
Strong winds have been named as the storms that blow in different shapes and too fast for a short time and are usually associated with unstable weather. If the unstable air have had humidity thunderstorms was happen other case was caused the dust storms. The purpose of this study was the analysis of ...
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Strong winds have been named as the storms that blow in different shapes and too fast for a short time and are usually associated with unstable weather. If the unstable air have had humidity thunderstorms was happen other case was caused the dust storms. The purpose of this study was the analysis of temporal oscillations of Thunderstorms in the North West of Iran (Ardebil, East Azerbaijan and West Azerbaijan) using spectral analysis. For this purpose, a daily 16-synoptic data (in the form of current weather data) of the Meteorological organization during the period 1988-2009 were used. In the following codes of 17, 29, 91 until 99 related to thunderstorms were identified. In order to analyze the Thunderstorms cycles in North West of Iran were used possibilities of programming in the Matlab software and Surfer software was used for graphical operations. The results showed that the frequency of the 2-year cycles is more than any other state; Therefore, the frequency of significant cycles, 2 cycles of 5 stations with the highest proportion allocated. Maku and Khoy and central stations, including stations of Tabriz, Maragheh, Mahabad and being involved, 6. 2-year cycles, respectively, and in terms of risk is most likely to occur in these areas.
Climatology
Yaghoob Rezazadeh; Bohloul Alijani
Abstract
Cold and freezinginthe North West ofthe country(Iran), has arrived allyearirreparabledamages to thetransportsectors, roadaccidents, gardens andagriculturalproductsandcrippled thenormal lifeof people incityand villagesAt first, theverycolddays of 18 stationsin the statistical periodwere extracted then ...
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Cold and freezinginthe North West ofthe country(Iran), has arrived allyearirreparabledamages to thetransportsectors, roadaccidents, gardens andagriculturalproductsandcrippled thenormal lifeof people incityand villagesAt first, theverycolddays of 18 stationsin the statistical periodwere extracted then of thestatistics, the number of 43 Severe and pervasive wave was selected..Finally, for Synopticanalysis ofcoldwaves, tworepresentativewaves on February1991 and January 2007were determined. The maps of Earth and the500Hpa pressuressurfaceof thefreezing from theNCEPwebsitehas been prepared andanalyzed. The results showed that in most cases of severe frost in the top level, a deep descends in the Iran west established and polar regionsCold Weatherwill leadtoIran. The establishment of above thebarrier in the East of this descends was due relativestagnation of descends and the continuity of cold inthe region intensifies. At the surface of Earth, west migrant high-pressures and the spread of Siberian high-pressure tab add to intensityat 500Hpa levels. Accordingly, we can at least 5 days prior to the deployment of these systems in the vicinity of the study area, predicted cold conditions, the managers and farmers are prepared to deal with cold.
Climatology
Mostafa Karimi; Elahe Ghasemi
Abstract
General circulation models (GCMs) are an important tool in the assessment of climate change. These numerical coupled models represent various earth systems including the atmosphere, oceans, land surface and sea-ice and offer considerable potential for the study of climate change and variability. However, ...
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General circulation models (GCMs) are an important tool in the assessment of climate change. These numerical coupled models represent various earth systems including the atmosphere, oceans, land surface and sea-ice and offer considerable potential for the study of climate change and variability. However, they remain relatively coarse in resolution and are unable to resolve significant subgrid scale features such as topography, clouds and land use. Bridging the gap between the resolution of climate models and regional and local scale processes represents a considerable problem for the impact assessment of climate change. Thus, considerable effort in the climate community has focussed on the development of techniques to bridge the gap, known as ‘downscaling’. In this study two statistical downscaling techniques (lars WG and SDSM) and Proportional Downscaling method have been sued , which are combination to TOPSIS approach.The result shows SDSM is more ability technique of downscaling. And climate change will reduce monthly rainfalls up to 39% and increase the temperatures up to 2 °C.
Climatology
Ali Mohammad Khorshiddoust; Robab Razmi; Nasim Maiali Ahari; Karim Abbaszade
Abstract
Subsidence is a natural phenomenon which can be reinforced by the interferences and activities of human beings. Ghaleh area in Tasuj is located in North Eastern part of Uremia Lake. The frequent occurrences of draught, expansion of agriculture and the over-population and thus over-exploitation of the ...
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Subsidence is a natural phenomenon which can be reinforced by the interferences and activities of human beings. Ghaleh area in Tasuj is located in North Eastern part of Uremia Lake. The frequent occurrences of draught, expansion of agriculture and the over-population and thus over-exploitation of the water belonging to underground beds and the delicate texture of soil have caused subsidence in some parts of the area. Regarding the existing evidences, the researchers are going to investigate the source of such a phenomenon in this area. To do so, we have used Geomorphologic and geologic data plus fault maps and hypsometric levels during 11 years period (2001-2011). integration and analysis of the maps by using ARC GIS software and the preparation of isopies maps for each of the monthly and annual by using Surfer win software and the cluster analysis based on tree diagram, showed that during the 11 years the amount of subsidence has increased due to the considerable reduction of underground water levels in some parts of the area such as Ghaleh village. On the other hand human factor has been recognized as the most important factor for the subsidence in the area.
Climatology
Mohama Raheimi; Mohamad Reza Yazdani; Moslem Asadi; Nafise Pegahfar; Mohammd Taleb Haydari
Abstract
Abstract The aim of this study is to investigate possible deviations from normal for Some climatic parameters in the Kurdestan. Calculation and analysis is done based on variables such as temperature, precipitation, humidity and maximum wind speed. Period examined in this study is a 30-year period between ...
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Abstract The aim of this study is to investigate possible deviations from normal for Some climatic parameters in the Kurdestan. Calculation and analysis is done based on variables such as temperature, precipitation, humidity and maximum wind speed. Period examined in this study is a 30-year period between 1983 and 2012 and is included Sanandaj, Saghez, Ghorveh, Marivan, Zarina Stations and Bijar At first, will identify data changes using the Mann-Kendall test. Then Characterized type and time of change. At the end Pearson correlation test was applied between variables. The results of data analysis indicate that start time of more changes is sudden and includes both the trend and fluctuation. Also, the results of the pearson correlation test suggests in most stations, there is positive significant correlation between rainfall and humidity and also negative significant correlation between temperature and humidity parameters.
Climatology
Majeid Rezaee Banafshe; Tahare Jalali
Abstract
According to important role of climate parameters such as radiation, temperature, precipitation and the evaporation in water resource management, The purpose of the present investigation, is evaluation of climate change in Tasuj basin and Groundwater level response to these changes in period 2013-2030 ...
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According to important role of climate parameters such as radiation, temperature, precipitation and the evaporation in water resource management, The purpose of the present investigation, is evaluation of climate change in Tasuj basin and Groundwater level response to these changes in period 2013-2030 by scenarios A2, B1, A1B. To do this research, was used the data of Chrchr and Sharafkhaneh evaporation stations and Khoy synoptic station for the period 1985-2012 and water levels data of tasuj basin for the years 2012-2000. Data of temperature, precipitation and sunshine with software LARS-WG and groundwater levels were predicted by artificial neural networks for mentioned period. The results revealed a decrease in precipitation and rise in temperature in each of the three studied scenarios.Maximum decline in water level in A2 scenario and minimum decline in groundwater levels will happen in B1 scenarios. Also study cross-correlation showed the impact of rainfall on groundwater levels is with time lag of 2 months.
Climatology
Hossein asakereh; Farieba Sayadi
Abstract
Artificial neural networks as a nonlinear techniques in climate and hydrology studies are important to have. Climate change and the global warming of the climate phenomenon known as persistence of drought followed Number of dry days. In this study, the data of daily rainfall during the period (1976-2008) ...
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Artificial neural networks as a nonlinear techniques in climate and hydrology studies are important to have. Climate change and the global warming of the climate phenomenon known as persistence of drought followed Number of dry days. In this study, the data of daily rainfall during the period (1976-2008) and artificial neural network in MATLAB software is used to predict the number of dry days Tehran station. Feed-forward type of network used by the algorithm reduces the gradient and Levenberg Marquardt is in the process of teaching and learning. Various structures in the input and hidden layers were tested during the training phase. Finally, a network with 4 inputs and 5 neurons in the hidden layer and 1 neuron in the output layer to best structure (4-5-1) with the highest correlation to predict the optimal answer. The results showed that the aforementioned stations, dry days predicted by the network during the period under review increased compared with that by calculating the probability of dry days during the period (2018-2009) using a Markov chain, the above been approved. The correlation coefficient values predicted dry days without a genetic algorithm combined with 86 percent .After teaching network as genetic algorithm combined with 88 percent that able providing algorithm combined to network result passable showing
Climatology
amanollah fathnia; Saeid Rajaee; Farzane Borzo
Abstract
In this study, using Gorgan station data for the period 2010-1980 was studied precipitation trends. In order to extract precipitation trend the moving average and Mann-Kendall test was used. Also, using by SPI (standard precipitation index) drought period and by Markov chain probability event each of ...
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In this study, using Gorgan station data for the period 2010-1980 was studied precipitation trends. In order to extract precipitation trend the moving average and Mann-Kendall test was used. Also, using by SPI (standard precipitation index) drought period and by Markov chain probability event each of the different states drought or wet period was calculated. Then, using NOAA-AVHRR images fluctuations vegetation affected by the precipitation trend and by Markov chain probabilities alternation for each class were examined. Results showed has occurred in 2001-2007 and 1990-1994 Years wet period and in 1982-1986 and 2005-2010 drought period. Study of drought index showed precipitation trend in same period and has occurred wet period in 2001-2005 and drought period from 2005. According to Markov Probabilistic matrix probability alternation from severe drought to same is 0.6 and severe drought to moderate drought is 0.13. In same trend, have decrease semi-dense vegetation from with 494479 hectares in 1985 to less than 380,120 hectares in 2000. Density and area of Vegetation have increased from 2000-2005, but for the reason of drought decrease recently and with 0.48 probabilities will remain non vegetation class in same conditions. The most probability changing is related to sparse vegetation to non-vegetation with 0.41. On this basis, may be will changed 214060 hectares to non-vegetation.
Climatology
Masoud Jalali; Ali SHahbai; Vahab Kamrian
Abstract
In this paper, we attempted to identify the synoptic patterns of Summer heavy rainfall in the southern coast of the Caspian Sea by using environment- to- circulation method. To attain this aim , by using statistics of daily Precipitation of 40 synoptic and climatology stations located in the region for ...
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In this paper, we attempted to identify the synoptic patterns of Summer heavy rainfall in the southern coast of the Caspian Sea by using environment- to- circulation method. To attain this aim , by using statistics of daily Precipitation of 40 synoptic and climatology stations located in the region for periods of 20 years of 1991 to 2010 and by percentile method , 29 days have rain more than 15 mm which have occurred in at least 30 percents of region stations , were determined as days with heavy rain. By using factorial analysis and cluster analysis methods , 3 synoptic patterns were determined as agent of creating rain in 29 days that the first pattern 48.3 percent , second pattern , 30 percent and the third pattern have allocated 21.7 percent of days of heavy rain in the studied region. In order to synoptic analysis of these patterns , maps of sea level pressure , 500 hectopascal level , omega (atmosphere vertical motions) , vorticity and moisture flows of level of 850 hectopascal related to two days before rain was used until rain day and finally it is determined that the main cause of occurring heavy summer rainfall in southern coast of the Caspian Sea is the penetration high-pressure system and after that formation of cool and moist northern flows as well as incidence of vast convection in the region. Each three patterns emphasize on occurrence of this condition and their difference is the place of deployment of high-pressure system and consequently the number of rainy days and severity of rain in these days.
Climatology
Broomand Salahie; Mahdei Aeli Jaham; Saiede Ainei; Jafar Derakshei
Abstract
The purpose of this study is forecasting the moderat and severs frost of three stations in Kermanshah, Kangavar and Sarpolezahab using output of the LARS-WG downscale model in the next two decades. The Input data's of models used in this study are: precipitation, minimum temperature, maximum temperature ...
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The purpose of this study is forecasting the moderat and severs frost of three stations in Kermanshah, Kangavar and Sarpolezahab using output of the LARS-WG downscale model in the next two decades. The Input data's of models used in this study are: precipitation, minimum temperature, maximum temperature and radiation in daily scale during the period 1992 - 2012. In the present study, using the output of two climate models, HADCM3 and BCM2 Under A1B Scenario, the initiation and end of the moderat and sever frost in these three periods 2030-2011, 2065-2046 and 2099-2080 have been evaluated. The results of the LARS-WG model process by the means of two Scheme Bcm2 and Hadcm3 indicate the warming of these stations in the coming years. The initiation of the moderat frost in these pointed stations is going to April by passing time. Between the stations in which are under study, Kangavar and Kermanshah stations have similar behavior but the Sarpolezahab station because of its tropic characteristic, showed a different behavior rather than the two stations in the coming years. The beginning of sever frost of these stations delayed with passing time and proceeds toward spring and in the other side, the end time of the last sever frost by passing time and getting close to the end of the anticipated period, is toward the beginning of winter and even at the Sarpole-zahab station until February. According to the results of the processing these models, the number of days with the moderat and sever frost in these stations will be dwindled in the coming years and the trend of temperature in these stations will be increased.
Climatology
Saeed Jahanbakhsh Asl; Shahnaz Rashedi; Mehdi Eslahi
Abstract
Freezing is one of the weather phenomena that almost happen in parts of the east Azerbaijan province such as Maragheh causing significant losses in agriculture, industrial activities, and transportation. The end of this research is studying of distribution and freezing return periods in Maragheh synoptic ...
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Freezing is one of the weather phenomena that almost happen in parts of the east Azerbaijan province such as Maragheh causing significant losses in agriculture, industrial activities, and transportation. The end of this research is studying of distribution and freezing return periods in Maragheh synoptic station during 48 year period (1343-1391) based on the minimum daily temperature. The methods of this study is Gumbel distribution method, three parameter log-logistic method and log-logistic method to analyzing probability of freezing parameters occurrence (starting date, ending date, length of the freezing season, length of the growing season).The Results of the computation of the spring and fall freezing return periods show that the first freezing in the fall starts on 10 Aban and the last freezing end on 17 Farvardin. Also analyzing of the beginning and end freezing trend shows that fall's freezing have an ascending trend , in other words, the dates of the occurring fall freezing goes ahead and spring's freezing have a descending trend. It means that, the dates of spring freezing go back. Therefore, length of the cold season according to the global warming becomes shorter.
Climatology
Hosein Asakereh; Mehdi Doostkamian
Abstract
The purpose of this study was to climate regionalization precipitation water atmospheric Iran. Therefore, the pressure data and specific humidity of the NCEP / NCAR database during 1950-2010 dependent of the United States National Atmospheric and oceanographic organization was extracted and analyzed. ...
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The purpose of this study was to climate regionalization precipitation water atmospheric Iran. Therefore, the pressure data and specific humidity of the NCEP / NCAR database during 1950-2010 dependent of the United States National Atmospheric and oceanographic organization was extracted and analyzed. For the calculation used software programming environment of Matlab and Grads software and Surfer software used to perform graphics operations. In the study for the perceptible water climate regionalization use from cluster analysis and in order evaluate the results, used of discriminant analysis. In the data archive mean and Coefficient of Variation precipitation water month review and analysis the method cluster analysis ward composition, than dendrogram graph recognized three regionalization climates: a) climate regionalization whit high precipitation water, b) climate regionalization whit median precipitation water. b) Climate regionalization whit low precipitation water. The result archives from discriminant analysis indict that 98.24% from of pixels doing so as true in relative group.
Climatology
Ataollah Nadiri; Keyvan Naderi; Asghar Asghari Moghaddam; Mohammad Hasan Habibi
Abstract
No permanent surface water resources in many parts of the country resulted in overdraft of limited underground water resources. Duzduzan plain is one of the UromiaLake sub basins. In this area, indiscriminate harvesting of groundwater resources has caused an average decline of 76 centimeters per year. ...
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No permanent surface water resources in many parts of the country resulted in overdraft of limited underground water resources. Duzduzan plain is one of the UromiaLake sub basins. In this area, indiscriminate harvesting of groundwater resources has caused an average decline of 76 centimeters per year. The purpose of this research is Groundwater level spatiotemporal predicting using Artificial intelligence models and Geostatistics model. To predict the groundwater level in the duzduzan plain, initially the piezometera in the plain were classified. The groundwater level in each piezometers category were introduced as output for each of AI models and input of these models include a evaporation and a precipitation and grounwater level of the considered piezometers with one time delay (t0-1), respectively. Ann's model and Sugeno fuzzy (SF) model applied to predict groundwater level. The resulted values of Groundwater level were evaluated by statistical measures, includes root mean square error and correlation coefficient. The obtained results showed ANNs model has better performance. Then the result of ANNs model, including two year monthly groundwater level prediction data in selected piezometers, were used as inputs of geostatistics model (Kriging and Co Kriging) for predating spatially ground water level in the study area. Obtained results showed Co Kriging model has better performance.
