Climatology
abdolreza kashki; sayed mohammad hosseini; farahnaz khoramabadi
Volume 23, Issue 67 , April 2019, , Pages 263-286
Abstract
Global warming is one of the current and future challenges for humankind which can have an impact on agriculture, transportation, water resources, energy production, architecture, heating and cooling needs of the building, plant phenology, etc. In this research, for the spatio-temporal analysis, the ...
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Global warming is one of the current and future challenges for humankind which can have an impact on agriculture, transportation, water resources, energy production, architecture, heating and cooling needs of the building, plant phenology, etc. In this research, for the spatio-temporal analysis, the need for cooling day was used from daily data of minimum temperature and maximum temperature of 16 stations in the north east of the Iran during the period of 20 years (1996-2015). First, data matrices were created in the MATLAB software with an S-dimensional array (7035*16), where are the rows, representing time (day) and columns, representing the locations (stations). Finally, it was calculated of cooling degree day per month and plotted spatial mapping in ArcGIS. The results showed that significant and reverse correlation between altitude and latitude with cooling day requirements in all warm months of the year, also according to the need for cooling degree day, the Khorasan area can be divided into six climatic groups. The most need for cooling with more than 500 degrees of day is in the southern and lowlands of the area and the least need for cooling are located in the northern and highlands part. So that the highest percentage of need for cooling day degrees in April and May white %27.5, related to the semi-cold climate group; In June with %24.5; in July %23.7; in august %22.4 and in September whit %22.5, Belongs to the cold climate group. Also, the study of the process of cooling needs suggests that in April most of the stations lack a significant trend, and only stations in the north and south of the region have a declining trajectory. In September, there is also a drop in cooling needs at most stations.
Climatology
faride habibi; Mahboobe Firoozabadi; fatemeh zarei
Volume 22, Issue 66 , January 2019, , Pages 141-162
Abstract
This research is investigated the precipitation system which created the significant rainfall and flooding in the southern and southwestern of Iran on the 14 and 15th March 2014, with using Metar and Synop reports from the synoptic stations of southern provinces; and weather patterns such as: mean see ...
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This research is investigated the precipitation system which created the significant rainfall and flooding in the southern and southwestern of Iran on the 14 and 15th March 2014, with using Metar and Synop reports from the synoptic stations of southern provinces; and weather patterns such as: mean see level pressure - advections of humid, temperature at 1000, 850 and 500 hpa - the pressure tendency over 24 hours at 500 hpa; wind field at 1000 and 200 hpa - and jet stream at 200 hpa. This rainy system was compared with the system of March 1996, which it had the second largest maximum rainfall in this region during the past 58 years. The weather patterns of March 2014 are quite different from patterns of March 1996. The first case has been created by potential instability due to the dynamic low pressure, but the latter has been formed by the combination of Mediterranean low pressure and Sudanese low. Of course, the gradual meridianization of the strong sub-tropical jet stream in the northwestern part of Africa, and penetration of its branch over the Persian Gulf have helped to intensify the instability of these areas on the mentioned days.The Maximum 24-hour rainfall has been reported from Bandarabbas, Rudan and Kahnuj stations that their amount was respectively 110, 78.5 and 69 mm. Three stations located in the easterly flank of precipitation system where there was the abundant moisture nutrition from the Strait of Hormuz. The left exit region of sub-tropical jet stream was situated over the hormozgan province and caused the lifting air flow in the region. The sum of these factors have caused the maximum rainfall occurs in this province
Climatology
Firouz Mojarrad; Bahman Farhadi; Zhila Olfati
Volume 22, Issue 66 , January 2019, , Pages 251-271
Abstract
Wheat is one of the most important strategic agricultural products which is crucial in providing food for the people of our country. The aim of this study was to assess the performance of AquaCrop plant simulation model, as one of the newest models, in determining the yield and planting date of rainfed ...
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Wheat is one of the most important strategic agricultural products which is crucial in providing food for the people of our country. The aim of this study was to assess the performance of AquaCrop plant simulation model, as one of the newest models, in determining the yield and planting date of rainfed and irrigated wheat in Kermanshah province. For this purpose, the rainfed and irrigated wheat yield was simulated by AquaCrop model using daily climatic data of five synoptic stations, including precipitation, maximum and minimum temperatures, potential evapotranspiration, wind speed and sunshine hours in a 22-year (1992-2013) period, as well as other environmental information. Among the dates entered to the model, the date that had the highest yield was selected as the best planting date. The results showed that from the point of view of yield, Ravansar and Sarpole-Zahab plains are more susceptible for planting rainfed and irrigated wheat, respectively. Wheat yield showed great sensitivity to changes in planting date. Planting dates in the stations were proposed from October 10 to November 20 for rainfed wheat, and from October 10 to November 10 for irrigated wheat, that match well with the actual dates of planting in the region. In general, AquaCrop model well simulated the different stages of growth and yield of rainfed and irrigated wheat according to the climatologic conditions of Kermanshah Province, and therefore could be an important tool to evaluate the potential wheat yield in the province and other regions with similar climates.
Climatology
Mohsen Armesh; Mahmood khosravi; Mohammad Saligheh
Volume 22, Issue 65 , November 2018, , Pages 45-62
Abstract
This study aimed to evaluate the variability of summer precipitation in the South East of Iran was selected stations and the precipitation associated was investigated with IOD index. For this purpose was used weekly precipitation data from June to September stations of Zahedan, Kerman, Bandar Abbas, ...
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This study aimed to evaluate the variability of summer precipitation in the South East of Iran was selected stations and the precipitation associated was investigated with IOD index. For this purpose was used weekly precipitation data from June to September stations of Zahedan, Kerman, Bandar Abbas, Iranshahr and Bam and weekly IOD index data. The method of this study is the correlation coefficient and discrete wavelet analysis. The results showed that in the positive phase of the IOD Index, warm air and humid of West Africa, sucked by low pressure the Persian Gulf and Pakistan and conditions creates convection in southeast of Iran, while IOD negative phase, in addition to shiftting the intertropical Convergence Zone, low pressure Persian Gulf and Pakistan are gone and West Indian Ocean for cooling than normal, stable atmosphere reigns. Summer precipitation correlation analysis between Bandar Abbas and Iranshahr with IOD index showed the strongest association. After the precipitation signal analysis of the stations showed of the Zahedan station on Level 4 and 3, respectively, at 99 and 95% was related to IOD index. The following series Kerman and Bam precipitation did not show any relationship with IOD index. Data analysis by the discrete wavelet transform showed that the most important cycle repeating 11-year occurred in the IOD index. Zahedan and Iranshahr showed periodic cycles relatively similarly. In Kerman was appeared 7-year cycle dominant and in Bandar Abbas and Bam the 11-year cycle. The process of reducing the number of weeks along with summer precipitation in the form of stations is contrary to the IOD index. But the increased intensity of precipitation stations is directly related to this index. Also Bandar Abbas, Iranshahr and Zahedan have more balanced precipitation cycles, but summer precipitation anomalies are intense in Kerman and Bam.
Climatology
khadijeh javan; ali akbar rasuli; mahdi erfanian; behroz sari sarraf
Volume 22, Issue 65 , November 2018, , Pages 83-100
Abstract
Rainfall is one of the most important elements to determine the climate. Therefore, it is important to estimate its value accurately. The main purpose of this study is the evaluation of the TRMM (Tropical Rain Measurement Mission) 3B42 rainfall estimates, an exponential model and conceptual cloud model ...
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Rainfall is one of the most important elements to determine the climate. Therefore, it is important to estimate its value accurately. The main purpose of this study is the evaluation of the TRMM (Tropical Rain Measurement Mission) 3B42 rainfall estimates, an exponential model and conceptual cloud model in Lake Urmia Basin. Therefore, this study focuses on the comparison of these methods to identify and select the most appropriate model for rainfall estimation in Lake Urmia Basin. The comparison are performed during the period 2007 to 2011 and the hourly rainfall, temperature, barometric pressure and dew point temperature, the three-hourly rainfall rate of TRMM 3B42-V6 at 0.25° resolution and thermal infrared images (TIR) of Meteosat 7 at six-hour intervals are used. The results indicated acceptable match of estimated rainfall with rain-gauge data. Comparison of three methods of rainfall estimation shows that exponential model has the determination coefficient (equal to 0.61). In addition to the high correlation, due to low levels of RMSE and MAE (respectively 1.58 and 1.01), has a good performance to estimate rainfall in this basin. Therefore, this model can introduced as the most appropriate model for estimating rainfall in Lake Urmia basin.
Climatology
Ali Mohammad Khorshiddoust; Fariba Esfandeyari; Seyed Asaad Hosseini; Parvaneh Dolatkhah
Volume 22, Issue 65 , November 2018, , Pages 141-162
Abstract
One of the new techniques in the field of predicting hydrological and geomorphologic processes is artificial neural network from the components of artificial intelligence which are trying to implement the amazing features of human brain in an artificial system and are powerful tools in the field of modeling ...
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One of the new techniques in the field of predicting hydrological and geomorphologic processes is artificial neural network from the components of artificial intelligence which are trying to implement the amazing features of human brain in an artificial system and are powerful tools in the field of modeling and predicting geomorphologic parameters and in this study have been used for the prediction of sediment in Aras basin. For this purpose was used information of discharge, sedimentation and prediction monthly on Borran hydrometric station located in the Basin of Darreh Roud that is from the main sub basin of Aras river in Moghan plain during the period of 34 years (water year of 53-54 to 86-87). So that the discharge and precipitation rate as inputs to the neural network and sediment was considered the output of network. For this purpose used the facilities and functions available in programming environment MATLAB / 2010 and SPSS / 21 software. Then models were evaluated through statistical parameters such as the determination coefficient, root mean square error, mean square error, mean absolute error, correlation coefficient and also mean percentage relative error. The results, in addition to confirming the capability of artificial neural network model, showed that, there is good correspondence between predicted values and observed data. So that the error mean of this model with the observed data is 0.9 and correlation coefficient is 0.99 which is significant at 0.01.The results of this study showed that the artificial neural. Network model has more accuracy in the estimation of sediment at the investigated basin. The results can be useful in planning and management of water and watersheds and natural resource management, especially in agriculture, industry, drinking and Forecast of Reservoir Sedimentation
Climatology
Batool Zeinali; Sayyad Asghari
Volume 22, Issue 65 , November 2018, , Pages 205-222
Abstract
Purposes of this research are introduction acceptable index for detection of dust storms and also identifying sources and pathways affected by this phenomenon in the East of Iran by studying a the dust storm using MODIS satellite images. For this purpose were used dust storm hourly data, satellite images ...
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Purposes of this research are introduction acceptable index for detection of dust storms and also identifying sources and pathways affected by this phenomenon in the East of Iran by studying a the dust storm using MODIS satellite images. For this purpose were used dust storm hourly data, satellite images of Modis and also digital and visual indexes including NDDI, BTDI, BTD, LRDI and false color composing for identifying dust storms. Finally, the studied dust storms were monitored using satellite images. Results indicated that LRDI index and false color composing have the higher resolution than the other indexes for detection of dust storms. Results monitoring dust storm event in the eastern Iran in summer indicated that storms sources of east area are dry beds of Hamoon lakes, Rigistan, Margo and Khas deserts at the convergence of the borders of Iran, Afghanistan and Pakistan and central Iran. The results of this research can be used in identifying of dust sources and pathways affected from this phenomenon by organizations and institutions to national and international planning.
Climatology
mostafa karimi ahmad abad; Adel Nabizadeh
Volume 22, Issue 65 , November 2018, , Pages 265-285
Abstract
Now days ,in order to providing the best mecanisms to damp the impact of climate change , climatology scientists need long term prediction of climatical variables and their changes. This research studies the impacts of climate changes on daily parameters such as: rainfall , min and max temperature and ...
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Now days ,in order to providing the best mecanisms to damp the impact of climate change , climatology scientists need long term prediction of climatical variables and their changes. This research studies the impacts of climate changes on daily parameters such as: rainfall , min and max temperature and sunshine hours in Urmia lake basin. (Tabriz ,saqqez and Urmia synoptic stations) , selected as study stations , have long term gaged data for mitigation and Adabtation from 1980 to 2009. data prediction under as scenario A2 a type of GCM as HADCM3 model was used to simulate climatic parameters in 2011 to 2040 by LARS-WG model downscaled. Results show that prediction time distribution has been limited to short time in comparison to past decades .In other words the number fraindy days has been diminished , as far as in the future April will have the most decrease (7.5%) and February will have the increase (5.8%) in precipitation . overall , the precipitation max and min averay temperature of basin will increase about (4.3%) , (1.35 ) and (0.64 ) respectively in addition, November will have the most increase in daily max temperature (12.7) and January will have the least increase (0.33) in this parameter the sunshine hours of basin will not increase significantly .
Climatology
Khalil Valizadeh Kamran; maryam longbaf
Volume 22, Issue 65 , November 2018, , Pages 287-299
Abstract
The agriculture is the sector that uses most of fresh water resources. Since the water resources are always subjected to severe depletion, the agriculture sector requires using the water with high efficiency and more effective ways One of the procedures leading to improvement of water management productivity ...
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The agriculture is the sector that uses most of fresh water resources. Since the water resources are always subjected to severe depletion, the agriculture sector requires using the water with high efficiency and more effective ways One of the procedures leading to improvement of water management productivity and ultimately to increase of water efficiency is the accurate estimation of the evapo-transpiration or estimation of water use efficiency of the crops. The remote sensing by giving an estimation of the degree of evapotranspiration (with little use of ground data) has a high potential for modification of cultivation patterns and management of water resources This research aims to determine the actual evapo-transpiration (need of water) of maize, which is an indigenous plant in the northern Khuzestan province, using the image processing of Landsat 8 in four passes include: 13 Aug, 14 Sep, 16 Oct and 17 Nov 2013 and also using the required metrological data based on Surface Energy Balance Algorithm for Land (SEBAL). The results showed that the amounts of needed water estimated by SEBAL model for maize in the initial growth stage, development stage, middle stage and the end stage are 5.04, 8.23, 5.55, and 1.46 mm per day respectively. The values from remote sensing were compared for values assessed by FAO- Penman-Monteith and evaporation pan methods and it was observed that MAE and RMSE are 0.45 and 0.18 mm per day compared to FAO- Penman - Montieth method. In sum, the results indicated that the SEBAL model is able to give answers with high accuracy and in short time and can be used as a beneficial and efficient tool in organizing water resources and meeting the plant water needs.
Climatology
Daryush Yar ahmadi; Saeed Basati; Behroz Nasiri; Somayyeh Rafati
Volume 22, Issue 65 , November 2018, , Pages 301-321
Abstract
Consequences and threats of climate hazards and opportunities such as water resources, agriculture and other economic sectors has caused Convective systems of precipitation are considered in recent years. Therefore, in this study, the dynamic conditions of mesoscale convective systems in the months warm ...
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Consequences and threats of climate hazards and opportunities such as water resources, agriculture and other economic sectors has caused Convective systems of precipitation are considered in recent years. Therefore, in this study, the dynamic conditions of mesoscale convective systems in the months warm and cold and their accumulation convective precipitation is investigated. After obtaining Geostationary satellites images, Meteosat and GOES, the most comprehensive of mesoscale convective systems without merge and split with the brightness temperature threshold of 224 K and area thresholds were determined and through the RegCM4, dynamic behavior and their accumulation convective precipitation was investigated. The results showed formation location of systems has been in southern Iraq and northern Saudi Arabia. The systems flows pattern of cold months of the year has been affected by altitudes pattern. So that positive vorticity in the region has been created on the collision of the elevation. Also the cores of dynamic quantities has been weakened after Zagros Mountains in months of December- January. Vorticity and convergence has been in April convective systems stronger and more intense than the months of December to January.
Climatology
Kazemeh Rangzan; Nazanin Ghanbari; Mostafa Kabolizade Kabolizade; Poria Moradi Moradi
Volume 22, Issue 64 , September 2018, , Pages 127-103
Abstract
Emission reduction of carbon dioxide and its impact on global warming process is one of the most important results in the use of renewable energy sources. In urban areas, solar systems stationed on building roofs are the most appropriate utilization method of stable source of solar energy. Urban compactness ...
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Emission reduction of carbon dioxide and its impact on global warming process is one of the most important results in the use of renewable energy sources. In urban areas, solar systems stationed on building roofs are the most appropriate utilization method of stable source of solar energy. Urban compactness is a major urban form parameter that affects the accessibility of solar renewable energy in the built environment, so it is essential that the effects of urban compactness on buildings utilization of solar energy, be surveyed. The aim of this study is the evaluation of solar energy potential in urban areas and determination of the relation between urban compactness indicators and solar energy potential in the local scale. In this study, the annual solar radiation modeling for each of the building surfaces of the study area, over one year period, was performed using the Solar Analyst model. On the other hand, the relation between various compactness indicators including site coverage, plot ratio, volume-area ratio, Entropy, population density and building density with Annual solar radiation received by the study area was explored and using least squares regression model, the relationship between the solar radiation and urban compactness indicators was determined. Also potential of using two types of active solar systems including Building Integrated Photovoltaic Systems (PV) and Solar Thermal Collectors (STC) was evaluated. According to the results, the annual solar irradiation increase from 507 (in compression areas) to 741 (in scattered areas) Kilowatt hours per square meter. Volume-area ratio shows the highest determination coefficient, R2 equal to 0/805 with annual solar radiation. Also in the study area, the building roofs potential for the development of PV systems much more than STC systems, influenced by the degree of urban compactness.
Climatology
Mohamad Saligeh; mohammadhosain naserzadeh; ali ghaffari
Volume 22, Issue 64 , September 2018, , Pages 129-147
Abstract
The mechanisms of climbing rainfall in different areas follow different patterns. Identification of those patterns can increase the environmental planning .The stability indicators which are known as instability indicators are relations through which we can study the amount of instability ...
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The mechanisms of climbing rainfall in different areas follow different patterns. Identification of those patterns can increase the environmental planning .The stability indicators which are known as instability indicators are relations through which we can study the amount of instability of convection of the atmosphere in any area for studying and predicting falls. These indicators are used for convection activities and basically are studied by thermodynamics diagrams and Radio sounds data. The main aim of this paper is studying the chronological features of precipitations over 5 mm .and determining convection precipitation parts of Tabriz spring station based on higher layers of atmosphere . the Tabriz station precipitation data were received from the weather organization cartulary regarding the 35 – year statistic periods and precipitation data for over 5 mm .were chosen while the time frequency was studied . After choosing the samples, the skew – T diagrams of precipitation days inadittion to the instability indicators such as (LI -TT – SI – KI – PW - CAPE)were analyzed . The processing of these data in seasonal scale indicate a frequent happening of those instabilities. The maximum occur once of the precipitations for the April with 131 frequency cases and minimum of this precipitator is in June with 35 cases were observed .The results of drawing skew – t diagrams and measuring the instability indicators show that the role of convection factor is important in spring precipitations because the convection factor is only the main factor not only the amount of convection is critical but also the needed instability for rain is provided. In general, after studying 263 rain samples in spring , it turned out that the convection factor has the most important role in rain occurrence in May and June and the hazards of flood threaten the area .
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.
