Climatology
Nafiseh Rahimi; Saeed jahanbakhsh; Brooman Salahei
Volume 23, Issue 70 , March 2020, , Pages 145-167
Abstract
Strong winds are one of natural disasters that sometimes cause enormous Financial and physical damages. Since northwest of Iran and specially Ardabil Province is one of windy regions, this study tried to identify synoptic patterns which bring strong winds. Through considering equal and threshold wind ...
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Strong winds are one of natural disasters that sometimes cause enormous Financial and physical damages. Since northwest of Iran and specially Ardabil Province is one of windy regions, this study tried to identify synoptic patterns which bring strong winds. Through considering equal and threshold wind speeding over 28 knots per second, 783 days identified as wind crashing days in Ardabil province. Then by data component- based analysis of 500hPa geo-potential height of the 783-days detected seven components which explain 92% of variance. Finally by clustering seven components identified ten patterns as synoptic patterns that are responsible for Strong wind of Ardabil province. The survey of topographic arrangement of these patterns indicates the rise of trough and ridge levels to these patterns. This means that the patterns consists of, mainly, trough, ridge, or combination of both and aren’t observed other systems such as cut off, block systems, etc. Although mentioned systems may be observe in individual patterns of each of the 783 days, but the systems aren’t responsible for the dominance and influence. The temporal distribution patterns show that two patterns, 6 and 7which occurs in the summer, has a similar system at 1000 hPa level when it compares with other models which occur in winter, spring, fall. What's notable, reversal of location position of pressure systems, 1000 hPa, in two patterns of summer, so that a low pressure instead of high pressure is over the Zagros and a high pressure instead of low pressure is over the Caspian Sea.
Climatology
Mohammad Reza Azizzadeyya Varzegan; khadijeh javan
Volume 23, Issue 70 , March 2020, , Pages 227-246
Abstract
One of the most important effects of climate change is increasing in extreme climate events. Change in the frequency or intensity of extreme events can have significant impacts on natural environments and human societies so their analysis is very important. The aim of this study is to identify the trend ...
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One of the most important effects of climate change is increasing in extreme climate events. Change in the frequency or intensity of extreme events can have significant impacts on natural environments and human societies so their analysis is very important. The aim of this study is to identify the trend of precipitation extremes in Lake Urmia basin and to investigate their relation with Teleconnection patterns. For this purpose, daily precipitation data of 7 synoptic stations in the basin during 1987-2014 was used. 11 extreme precipitation indices were extracted using the RClimDex and their trends were calculated by non-parametric Mann-Kendall test. Then the relationship between these indices with Teleconnection patterns was determined by the Pearson correlation coefficient. The results of time series analysis showed that all extreme precipitation indices in Lake Urmia basin have decreasing trend exept consecutive dry days (CDD). The spatial distribution of trend in extreme indices showed almost all indices have a significant trend at the 5% significance level in basin. There is no significant trend in consecutive dry days (CDD). The changes in extreme precipitation could be affected by the El Niño-Southern Oscillation (ENSO), Southern Oscillation Index (SOI), East Pacific-North Pacific (EP-NP), Madden and Julian Oscillation (MJO) and Pacific Decadal Oscillation (PDO).
Climatology
ali akbar rasouli; elnaz ostadi; mohammad reza aziz zade
Volume 23, Issue 69 , December 2019, , Pages 87-103
Abstract
The consequences of climate change in drought areas such as Iran, temporal and spatial changes are the distribution and concentration of rainfall, which can affect water resources. On the other hand, increasing the concentration of rainfall can causing hazards such as floods . The importance of the issue ...
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The consequences of climate change in drought areas such as Iran, temporal and spatial changes are the distribution and concentration of rainfall, which can affect water resources. On the other hand, increasing the concentration of rainfall can causing hazards such as floods . The importance of the issue of distribution and concentration of rainfall has encouraged researchers to study in this regard. Concentration Index (CI) is a method which is used to study the distribution and concentration of rainfall. This study was performed to calculate and analyze 23 station daily precipitation concentration index in Northwest of Iran during 1951 to 2015. In this research range of CI values calculated between 0.57 for Khoy station to 0.67 for Maku station and average 0.61 for all station. CI map obtain from values Interpolation and showed that the Northwest part of the study area with Maku station depute, compared to other regions, especially in central areas such as Tabriz station is not uniformly distributed. Also Northwest area with an average of 0.61 compared with an average CI of Iran ( 0.64) is more evenly precipitation distributed throughout the year.
Climatology
Jaber Soltani; masoud ahmadi nik; Ahmad Ahmadinik
Volume 23, Issue 69 , December 2019, , Pages 127-147
Abstract
Reference evapotranspiration is one of the necessary parameters to determine crop water requirements and irrigation planning. Having accurate estimates of this parameter is essential for planning and managing of water resources. Several experimental models have been proposed to estimate evapotranspiration. ...
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Reference evapotranspiration is one of the necessary parameters to determine crop water requirements and irrigation planning. Having accurate estimates of this parameter is essential for planning and managing of water resources. Several experimental models have been proposed to estimate evapotranspiration. According to the spatial variability of climatic parameters, using remote sensing method that considers these changes is very favorable. Among the most widely used models that accurately estimate evapotranspiration using remote sensing, can be mentioned wavelet model. In this regard, the purpose of present study is to evaluate the accuracy of wavelet models to estimate the reference evapotranspiration using parameters derived from satellite images contains the Earth's surface temperature and amount of water vapor in the atmosphere. In this study, used atmospheric and satellite images data of four station contains Anar, Kerman, Rafsanjan and Shahrebabak to develop and evaluate wavelet models. In the first scenario, temperature, in the second scenario, atmosphere water vapor parameter and in third scenario, both parameters simultaneously was used as the model input. Results of this study showed that despite the high accuracy of models in different scenarios, the wavelet model use two-parameters, temperature and steam simultaneously (third scenario), with a coefficient of 90% compared to other models had the more accurate.
Climatology
esmaeil abbasi; mahdi khazayi
Volume 23, Issue 69 , December 2019, , Pages 175-190
Abstract
One of the most devastating phenomena of meteorology which varies extensively in spatial and temporal extent and manifests itself at various scales, is thunderstorms. The purpose of this study was to identify and analyze such destructive storms over a period of 25 years (1986-2010) at the synoptic station ...
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One of the most devastating phenomena of meteorology which varies extensively in spatial and temporal extent and manifests itself at various scales, is thunderstorms. The purpose of this study was to identify and analyze such destructive storms over a period of 25 years (1986-2010) at the synoptic station of Kermanshah. The data used in this research includes daily rainfall data and codes related to meteorological phenomena, dry temperature, dew point, relative humidity, wind direction and wind speed for calculation of instability indices, geopotential height parameters, specific humidity, vertical velocity, and zonal and meridional components. The results showed that during the statistical period of the study, three extreme thunderstorms occurred in the study area during the statistical period of 25 years. The study of instability indices indicates that these indices are in the strong and suitable category for the occurrence of thunderstorm phenomenon; in addition, the dynamics of the atmosphere at the time of the occurrence of this phenomenon indicates the presence of a very deep trough and negative abnormalities in the west of the studied region and positioning of the left half of the Jetstream of levels of 500 and 850 millimeters on the studied area. Following this phenomenon, the thunderstorm intensely affected the region by its destructive effects with the formation of clouds of cumulus and lightning, and finally, heavy rainfall. However, it should be mentioned that for two cases, that is, the phenomenon of February 4, 2007 and December 12, 1991, they experience a more unstable climate due to the average circulation patterns compared to the other identified case, i.e. the phenomenon of April 17, 1991.
Climatology
Hossein Asakereh; Mokhtar Fataheyan
Volume 23, Issue 69 , December 2019, , Pages 191-211
Abstract
Atmospheric circulation is a fundamental factor in determining the climatic conditions of every region (Mofidi and Zarrin, 1391). Therefore, the climate framework of every location is based on large-scale systems. One of the most obvious and permanent tropical landscapes along the northern and southern ...
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Atmospheric circulation is a fundamental factor in determining the climatic conditions of every region (Mofidi and Zarrin, 1391). Therefore, the climate framework of every location is based on large-scale systems. One of the most obvious and permanent tropical landscapes along the northern and southern tropical hemisphere as cores of high-pressure centers or high-altitude bands is called the "tropical high-pressure" system. The subtropical high-pressure cores are known in various areas under various names (such as high-pressure azure, high-pressure Saudi, etc.). For example, Mason and Anderson (1963) define the most intense and permanent anticyclone as the Asian Anticyclone studying the two levels of 100 and 50 hPa and by investigating daily weather-condition maps during 1957-59. Since the spatial-temporal variance and intensity change of this system causes anomalies in regional and global circulation and consequently climatic anomalies, therefore, due to the geographical location of Iran relative to the climate of the above system, the spatial variations of this system have significant effects on Iran.
Climatology
Mostafa Karimi; Faramarz Khoshakhlagh; ali akbar shamsi por; fahimeh noruzi
Volume 23, Issue 69 , December 2019, , Pages 233-255
Abstract
Large-scale circulation patterns are controlling climatic conditions and especially precipitation of the area. The purpose of the study is investigating the relationship between circulation patterns of Arabian subtropical anticyclone and Iran precipitation. For this reason, was used re-analysis data ...
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Large-scale circulation patterns are controlling climatic conditions and especially precipitation of the area. The purpose of the study is investigating the relationship between circulation patterns of Arabian subtropical anticyclone and Iran precipitation. For this reason, was used re-analysis data of geo-potential height form European Center for Medium-Range Weather forecasts (ECMWF), with spatial resolution of 1*1 degree and correlation distance cluster analysis. Circulation patterns at 30 to 80 degrees the East longitudes and5 to 30degrees north latitudes and the period of11years (2000- 2010) was calculated. The results showed that the patterns in terms of occurrence were divided the patterns of the cold period, the warm period and the transition period. During the cold period anticyclone is located at down latitudes on the Arabian sea and Gulf of Aden and have precipitation more areas of Iran that maximum amount of precipitation is related to the second pattern. In the patterns of transition period Arabian anticyclone sent a southwest clockwise current in to the trough East Mediterranean is effective in the occurrence of precipitation in the area of North and Northwest of the country. In the patterns warm period the anticyclone caused the anticyclone conditions on country and has been as a barrier to entry precipitation systems.
Climatology
KARIM AMININIA; Ali Mahmoudei
Volume 23, Issue 68 , September 2019, , Pages 23-45
Abstract
One of the things done in the field of synoptic climatology is air typology. An air typology represents types of air that are similar enough in terms of particular atmospheric variables. The emergence of an air type in a certain area, on one hand, depends on the air masses entering to the area, and on ...
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One of the things done in the field of synoptic climatology is air typology. An air typology represents types of air that are similar enough in terms of particular atmospheric variables. The emergence of an air type in a certain area, on one hand, depends on the air masses entering to the area, and on the other hand, reflects the geographic conditions (roughness, adjacency to the masses of water, etc.) of that area. Since the geographic conditions of each area are usually constant, the difference in air types that come and go in the region is a function of the air masses that enter the area. Characteristics of the air masses while moving and crossing different areas, change, adjust and turn into another air. Given the fact that the repetition of air types determines the climate in an area, it is very important to identify the types of air. This is because without knowing the types of air dominating an area, management and planning will be very difficult and even impossible. This is while by identifying air types, it will possible to identify possible types of natural disasters in different sectors of agriculture, industry, etc. and prevent its damages. Since each type is related to circulation patterns, recognizing the characteristics, severity, and frequency of each type can show us their remaining time and duration of their domination, and help us in planning
Climatology
gholam hassan jafari; Hazhir Mohammadi
Volume 23, Issue 68 , September 2019, , Pages 47-69
Abstract
Changes in the base levels are the most important factors of forms and processes’ imbalance in drainage basins. Ghezel Ozan basin, which is the sub-basin of Caspian Sea, has had many effects on base level fluctuations. In this study, Channels and Lithology were evaluated using GIS software and ...
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Changes in the base levels are the most important factors of forms and processes’ imbalance in drainage basins. Ghezel Ozan basin, which is the sub-basin of Caspian Sea, has had many effects on base level fluctuations. In this study, Channels and Lithology were evaluated using GIS software and topographic and geological maps. Using evidences, the base level changes including the capture and diversion of convergent radial rivers and channels of Bijar geo-neuron in Qezal Oazan Basin were identified. Also, the relationship between branch and length of the channels in Bijar sub-basins was investigated using the fractal geometry theory and Horton- Strahler stream ordering method and their fractal dimension was calculated. The results show that the effects of changes in local base levels of Bijar hole can be traced as aggregate levels in the alluvial plains of 6 sub-basins of Angouran-Chay, Hassanabad Yasukand, Yol-Kashti, Ghorveh and Dehgolan, Garmab and Sujasrud. The prospecting process is visible in the center of the hole. At elevations of 1561, 1540 and 1515 meters in Bijar hills, 3 lake terraces have been observed. The fractal number of 2.12 of Bijar basin indicates that the whole basin is in a relatively moderate condition and the retardation erosion in the branches is going to be stopped. In the two sub-basins of Yol-Keshti and Ghorveh-Dehgolan, fractal dimension of less than 2 shows that the coefficient of branching is greater than the basin area. At the head of the water at the Angoran Chay, Sujasrud and Garmab sub-basins, the branches are still developing and retreating. Hassanabad Yasukand sub-basin with the highest fractal number among the sub-basins (3.25) reaches its maximum balance and the lowest erosion is dominant in its branches. Investigating the relationship between fractal dimensions and branching ratio with the area of the studied basins indicates a reverse and negative relationship.
Climatology
Ali Mohammad Khrshieddoust; Hamid Mirhashemi; Mousa Nazari
Volume 23, Issue 68 , September 2019, , Pages 71-90
Abstract
Evaporation is one of the important factors in the hydrological cycle and is one of the determinants of energy equilibrium at ground level and water balance, which is required in various areas such as hydrology, hydrology, agriculture, forest management, and management of water resources (Sanei Nejad ...
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Evaporation is one of the important factors in the hydrological cycle and is one of the determinants of energy equilibrium at ground level and water balance, which is required in various areas such as hydrology, hydrology, agriculture, forest management, and management of water resources (Sanei Nejad et al., 2011). In this regard, one of the basic data in designing irrigation and drainage networks is the amount of evaporation power in each region. Because the design of transmission networks, such as drainage or drainage channels, as well as other parts of water design, depends on the amount of water required by the evaporation phenomenon (Jahanbakhsh et al., 1380). In general, evaporation hydrology is generally referred to as the phenomenon of water It simply turns steam into a physical process.
Climatology
somyyeh Soltanei; Soheila Zareh; Mahdei Taze
Volume 23, Issue 68 , September 2019, , Pages 157-177
Abstract
Rainfall erosivity factor is the most important factor influencing soil erosion. Various indicators has been developed to quantify it. Selection the appropriate index due to ecological conditions is necessary. Therefore mapping rainfall erosivity and awareness its changes, plays an important role in ...
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Rainfall erosivity factor is the most important factor influencing soil erosion. Various indicators has been developed to quantify it. Selection the appropriate index due to ecological conditions is necessary. Therefore mapping rainfall erosivity and awareness its changes, plays an important role in soil conservation, erosion control and land management. The purpose of this study is the selection of the best geostatistic method for mapping the rainfall erosivity factor in Fars province. In first step Fournier factor was calculated for 42 stations in Fars province and its surrounding and was determined the best geostatistic method using IDW, GPI, LPI, RBF, Ordinary and Simple and was prepared zoning map for Fournier factor. The results showed that among the various geostatistic techniques, RBF method (Thine plate Spline) is the best method for mapping rainfall erosivity factor in Fars province. Also, Noorabad city in northwest of province with an average of 31.6 mm Fournier and Izadkhast city with 8.67 were determined as the highest and lowest of the erosivity index. Also, Fournier index has increased from the East to the West as 46% of the province has a low erosion and 3% of the province has been high erosion that have had the highest and lowest levels.
Climatology
Behrooz Sari Sarraf; Shoaieb Abkharabat
Volume 23, Issue 68 , September 2019, , Pages 179-193
Abstract
As a core of wind speed, Low Level Jet (LLJ) of the Persian Gulf is made on the Persian Gulf and its surrounding in the low levels of the atmosphere during the hot period of the year. Known as north wind, this jet appears in the body of a more extensive current of wind with the northern, northwestern, ...
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As a core of wind speed, Low Level Jet (LLJ) of the Persian Gulf is made on the Persian Gulf and its surrounding in the low levels of the atmosphere during the hot period of the year. Known as north wind, this jet appears in the body of a more extensive current of wind with the northern, northwestern, southern, southeastern direction. North wind often blows from the mountainous regions of Turkey and Iran to the southern regions. Except for topographic reasons, the formation of this wind is influenced by hollow topography of low regions of Mesopotamia and Khouzestan appearing as a corridor. Reaching the Persian Gulf, this phenomenon is intensified as the water area of the Persian Gulf is besieged as a low hollow by Zagros Mountains and Arabic Peninsula aggravating the wind.
Climatology
Saeed jahanbakhsh; yagob din pazhoh; mohammad hossein aalinejhad
Volume 23, Issue 67 , April 2019, , Pages 91-107
Abstract
According to the importance of snowfall in supplying water of different regions especially mountainous areas, accurate estimation of snow water equvallent and changes of its coverage would be effective in agriculture, energy, management of reservoir and flood warnings. In this study runoff orginated ...
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According to the importance of snowfall in supplying water of different regions especially mountainous areas, accurate estimation of snow water equvallent and changes of its coverage would be effective in agriculture, energy, management of reservoir and flood warnings. In this study runoff orginated from snow melting in ShahrChay basin under the terms of climate change calculated. For this purpose, snow cover for water year of 2012-2013 were extracted in ENVI software by using daily images of Modis satellite.Then, GIS software the physiographic specification of the basin was obtained. In the next step, data of snow cover, meteorological variables and other necessary parameters to SRM model provided as an input of model and run_off from snow melt was simulated. Then output of the 6 models of atmospheric general circulation with title of 3 scenarios nomely A1B , A2 and B1 converted to a downscaleing by using LARS-WG model. By comparing the output of 6 models in the future period to period based on monthly statistical, the best model and scenario for generation of air temperature and precipitation data in the period 2030-2011 were selected. As a result the HADCM3 model under the scenario A1B was used for generation of precipitation and the MPEH5 under scenarios A2 was used for generation of temperature data. In order to estimate the rate of change of runoff orginated from snowmelt rate of change of monthly data of air temperature and precipitation of the base time period as well as future time period under selected model and scenarios was entered to SRM model in simulation time period. Results for all of the scenarios show that runoff orginated from snowmelt in late spring will be reduced. The peak flow appeared earlier in comparison with base time period and its value would be larger than base time period.
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 .
