Climatology
Gholam abbas Fallah Ghalhari; Mehdi Asadi; Alireza Entezari
Volume 19, Issue 54 , February 2016, , Pages 235-251
Abstract
Climate classification and identifying the most effective factors and elements of each area is one way of understanding identity of the climate zones. Therefore, to identify Guilan climate mapping new methods such as factor analysis and hierarchical cluster were performed. For this, we used 20 climate ...
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Climate classification and identifying the most effective factors and elements of each area is one way of understanding identity of the climate zones. Therefore, to identify Guilan climate mapping new methods such as factor analysis and hierarchical cluster were performed. For this, we used 20 climate variables of the 16weather stations in the study area. Then, using interpolation method, a matrix with dimensions of 20×106 data was obtained. Climate mapping of the province with factor analysis showed that the climate of the province is made up of two factors. These two factors are: humid-rain–wind and temperature–cloudy factors. Results also indicated that these two factors explain 99.44 percent of the variance of the primary variables. The contribution of each factor was 64.49, 34.95 percent respectively. Finally, cluster analysis on two climatic factors identified three climatic regions in the provinces. These three regions are: moderate and humid, mountainous, semi humid and cold.
Climatology
Yousef Ghavidel Rahimi; Mohammad Rezaei
Volume 19, Issue 54 , February 2016, , Pages 253-277
Abstract
Heat waves are considered as one of the important climatic hazards in the world and especially in Iran and it seems that, due to intensification of global warming, their occurrence has increased in recent years than in the past. This study has paid attention to quality and quantity evaluation and synoptic ...
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Heat waves are considered as one of the important climatic hazards in the world and especially in Iran and it seems that, due to intensification of global warming, their occurrence has increased in recent years than in the past. This study has paid attention to quality and quantity evaluation and synoptic analysis of heat waves in the KermanProvince. For this purpose, At first, the daily maximum temperature data, in month of July (as the warmest month in the year) was put in a statistical period of 24-years (1986-2009) from meteorological organization, for 4 synoptic stations of Kerman, Bam, Anar and Sirjan. In order to classify heat waves, standardized temperature data and on its basis, anomalies of 0 to 0.75 as a heat wave, 0.75 to 1.5 as severe heat waves, and greater than 1.5 were determined as super heat wave. The threshold values of 43.1, 42.1 and 41.2° C were calculated for all stations, respectively as threshold of heat wave, severe heat wave, and super heat wave and its continuity were considered at least for two days. Accordingly, During Statistical period of study, it was found 7 heat waves, which were, identified within 3 severe heat waves, and 1 super heat wave. Super heat wave in July 1998, was selected For the Synoptic analysis. This three-day wave, with an average temperature of 43/11° C, has been the most severe heat wave in KermanProvince. Results of synoptic analysis of super heat wave indicated that the establishment of Ganges low pressure on the ground and the domination of subtropical high-pressure of azores in high levels and also, high thickness atmosphere on the study area caused the subsidence of warm air and excessive heating of earth's surface, and created them mentioned super heat wave.
Climatology
Peyman Mahmoudi; Mahmood Khosravi; Seyed Abolfazl Masoodian; Bahlol Alijani
Volume 19, Issue 54 , February 2016, , Pages 303-327
Abstract
To identify and detect the frequency variation trend of Iran’s pervasive and semi-pervasive frost days in the current research, minimal daily temperature data of 663 Iranian climatology and synoptic stations were acquired from Iran Meteorology Organization during the time interval between 1962 ...
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To identify and detect the frequency variation trend of Iran’s pervasive and semi-pervasive frost days in the current research, minimal daily temperature data of 663 Iranian climatology and synoptic stations were acquired from Iran Meteorology Organization during the time interval between 1962 and 2004 for October to April months. Following data acquisition, Iran’s isothermal maps for each day starting from 1.1.1962 until 31.12.2004 (9116 days) were prepared using Kirging interpolation technique in order to construct the database of the county’s minimal temperature. In the next step, frosts were classified in three types based on a spatial principle: pervasive frosts (simultaneous occurrence in more than 65% of Iran’s surface area), semi-pervasive frosts (simultaneous occurrence in 25% - 65% of Iran’s surface area), and local frosts (simultaneous occurrence in less than 25% of Iran’s surface area). Then, frequency of pervasive and semi-pervasive frost days were analyzed in three scales including monthly, seasonal, and yearly using two estimation techniques of slope SENSE and linear regression.
Results indicated that frequency of pervasive frosts in Iran held a statistically significant decreasing trend in December and January months, during winter, and also, in annual basis. But, for semi-pervasive frost days, it was observed that variation was significant only in January having a positive trend. It signifies that number of days with semi-pervasive frost increased during the 43 years under study. Therefore, number of semi-pervasive frost occurrences increased while number of pervasive frost occurrences decreased in January. The same rule holds for other scales i.e. monthly, seasonal, and yearly basis.
Climatology
Mohamad Reza Aphsharei Azad; Halea Pouraky
Volume 19, Issue 53 , September 2015, , Pages 1-24
Abstract
Rivers across the nation in terms of conservation, utilization and development of as well as quantitative and qualitative evaluation of favorable river conditions for fish to be used. This study is analysis of factors that is necessary to apply physiographic models of river which have role on topology ...
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Rivers across the nation in terms of conservation, utilization and development of as well as quantitative and qualitative evaluation of favorable river conditions for fish to be used. This study is analysis of factors that is necessary to apply physiographic models of river which have role on topology of stations of fish culture(salmon), in addition to factors which have been used currently in this field, Sham rood river has been studied in terms of physiography. Results of survey among various factors are indicating importance of physiography of studied location that is usable for constructing workshops of fish culture; Sham rood river is regarding to biologic and frequency indices, its potential power to produce fish is 348 kg.hec. This production is high since Farvardin until Shahrivar and then Khordad has highest amount of fish production. Effective factors include physiographic patterns such as area and perimeter, form of basin, height, inclination, and direction of inclination. These results in analysis of future procedures show condition of topology of fish culture pools' construction and physical and mechanical elements of fish culture such as PH of water, velocity of water flow, light effect, degree of water turbid, suspension solids, solidity of water, electric conduction of water (EC), chemical materials, water salinity, rate of required water show biological factors. Finally, check the condition of steep mountainous watersheds for fish with cold water and put the channel maps, political spots, lithology, slope, aspect factors needed to put them together with the salmon farming appropriate the construction of stations and half fish and unfavorable conditions for fish and plant construction has been determined ..
Climatology
abasali Arvin
Volume 19, Issue 52 , June 2015, , Pages 25-42
Abstract
Variations of ozone layer that measure by name of total ozone (TO) oscillation are one of the modern humane concerns as one of causes or manifestations of climate change. In this research total ozone oscillation in relationship with Sea Surface Temperature (SST) in Pacific Ocean has been studied. For ...
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Variations of ozone layer that measure by name of total ozone (TO) oscillation are one of the modern humane concerns as one of causes or manifestations of climate change. In this research total ozone oscillation in relationship with Sea Surface Temperature (SST) in Pacific Ocean has been studied. For this aim monthly mean data from the satellites in point by 1*1.25 degree of geographical distance and monthly mean of NINO1+2, NINO3, NINO4 and NINO3.4 indices have been used. The results show that total ozone in positive\negative occurrence of SST has been increased\decreased in all Iranian areas. The asynchronous relation of effects SST indices have been tested on (TO). The strongest relations in lag time of months 5, 1, 5 and 2 respectively are for NINO1+2, NINO3, NINO4 and NINO3 indices. The correlation of NINIO1+2 with TO are better than other indices and the strongest correlation was in west and northwest of Iran. The average of synchronous and asynchronous (5 months lag time) correlation coefficient between NINIO1+2 with TO on all areas of Iran was respectively r=+0.55 and r=-0.621. The in synchronous correlation was direct and significant at 0.05 level in 86 precent of areas of Iran but asynchronous correlation was indirect and significant at 0.05 level The relation of NINO4 with (TO) was the weakest correlation in other indices.
Climatology
nahideh Jahedi; mohammadali Ghorbani
Volume 19, Issue 52 , June 2015, , Pages 63-63
Abstract
Being aware of decreasing or increasing trend of precipitation and discharge in watersheds has very important role in water resources management and the subjects relating to water engineering. In this study, the trend of precipitation and discharge at Qara-su River Basin in Ardebil has been studied in ...
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Being aware of decreasing or increasing trend of precipitation and discharge in watersheds has very important role in water resources management and the subjects relating to water engineering. In this study, the trend of precipitation and discharge at Qara-su River Basin in Ardebil has been studied in monthly, seasonal and annual timescales over the period from 1351 to 1382. For investigation of the existence or absence of a trend, Mann-Kendall test was used by detecting effects of all auto correlations coefficients, and Sen’s estimator was used at different significant level to evaluate the magnitude of the test. The results of the calculated values for precipitation and discharge data set indicated that the trend of the Qara-su River discharge was decreasing for both stations in annual timescale. Also, decreasing trend of discharge dataset was found for seasonal timescale in spring, autumn and winter in which significant trend belonged to winter season. Maximum value of decrease for discharge is for Doustbiglo station in spring (-0.62 m^3/s), and the minimum value of decrease for discharge in summer for this station, too. Furthermore, there was not significant trend for precipitation dataset in monthly, seasonal, and annual timescales.
Climatology
Mahmood Khosravi; Nematollah Safarzaie; Mohsen Armesh
Volume 19, Issue 52 , June 2015, , Pages 113-140
Abstract
Frost is one of the natural disasters that is usually are associated with financial losses and even mortality. The atmospheric circulation systems have a main role in the occurrence, severity and spatial distribution of frost especially in temperate regions. The purpose of this research is the detection ...
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Frost is one of the natural disasters that is usually are associated with financial losses and even mortality. The atmospheric circulation systems have a main role in the occurrence, severity and spatial distribution of frost especially in temperate regions. The purpose of this research is the detection and investigation of synoptic conditions simultaneous with occurrence of winter frosts in Sistan region. The method used in this analysis approach is peripheral circulation. For these purposes, two databases (surface and atmospheric) were required. For surface data, climate data from synoptic weather stations of Zabol and Zahak were used as a representative of the regional climate. The longest and most severe frost was selected during the last decade (2010-2000). Second database of sea level data and maps of 850 and 500 Hp levels was prepared from the National Center for Environmental Prediction (NCEP) and National Center for Atmospheric Research (NCAR). Spatial coverage of weather data is between 30 until 90 degrees east longitudes and 10 until 50 degrees north latitude. For representing the weather stream lines maps, Grads software was used. The results showed that cyclonic activity on the Balkhash Lake prepared the situation for downfall of cold air of high latitude and western flow of trough to region and caused frost in the Sistan region. Transferred axis of trough at the eastern regions and the above conditions caused more frost persistence. The most severe frost in Sistan region tll, place in the western part of trough and the flux of northern cold air. The factor that has created these conditions is the pressure gradient between the southern and northern regions of Sistan, especially South East of Sistan low-pressure system which led to the establishment of west part of trough to the region.
Climatology
ali Mohammad Khorshiddoust; Behrooz Sobhani; Kamel Azarm; Jamal Amini
Volume 19, Issue 52 , June 2015, , Pages 141-161
Abstract
Canola is the world third leading oil seed after soybean and oil palm by producing 15 percent of the global plant oil. Climate, topography and lands capability are the most important environmental factors on which the crop production capability in a region depends. Therefore by evaluating these factors ...
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Canola is the world third leading oil seed after soybean and oil palm by producing 15 percent of the global plant oil. Climate, topography and lands capability are the most important environmental factors on which the crop production capability in a region depends. Therefore by evaluating these factors one can identify suitable lands for canola cultivation. In the present study, the climatological data such as temperature, precipitation, growth degree day, relative humidity, freezing days, and sunshine hours were collected from the West Azerbaijan province synoptic and rain gauge stations (since their installation untill 1388) which were associated with the phenologic stages of canola growth. In addition to the climatological data, earth resources like topographic layers, lands capability, soil depth and land-use were analyzed focusing on the climatological and ecological requirements of canola. After generalizing the data and processing by using ArcGIS, their corresponding information layers were derived. In order to prioritize and assess the criteria and information layers in relation to each other, the multi criteria decision method was employed based on analytical hierarchy process. Then, combination and spatial analysis of the information layers using TOPSIS model and GIS capabilities were done and the final capability ecological evaluation layer for canola cultivation was produced. Based on the obtained results, the province lands were divided into four categories of highly suitable (%18.6), suitable (%34.4), moderate (%32.1) and weak (%14.7) lands on the basis of the environmental and climatologocal potentials for canola cultivation.
Climatology
Bahlol Alijani; Hasan Farajzadeh
Volume 19, Issue 52 , June 2015, , Pages 229-256
Abstract
Natural environment is regulated according to the climatic conditions. Human communities are forced to adjust themselves to these conditions. Identifying the intensity, frequency and timing of climatic events can help solve the environmental problems and ease the coherent planning to mitigate these events ...
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Natural environment is regulated according to the climatic conditions. Human communities are forced to adjust themselves to these conditions. Identifying the intensity, frequency and timing of climatic events can help solve the environmental problems and ease the coherent planning to mitigate these events changing behavior. To achieve this objective in the Northwest of Iran, daily minimum and maximum temperature data from 13 stations were obtained from the Meteorological Organization of Iran in the quality control format for the existing data period. Sixteen Extreme indices were extracted by RClimDex package and their changing behavior was checked by Mann – Kendall method. The results showed that the frequency of cold indices decreased but the frequency of extreme warm indices increased during the study period. According to the results of wavelet analysis all the extreme cold indices showed a significant periodic fluctuations of 2 to 4 years. Among the warm indices only the warmest days index (TXx) showed 2 to 4 years fluctuation and the number of tropical nights (TR20) exhibited 4 to 8 years of significant fluctuation.
Climatology
Rasool Mirabbasi Najafabadi; yaghoob Dinpashoh
Volume 19, Issue 52 , June 2015, , Pages 277-301
Abstract
The aim of this study is the analysis of surface wind speed in monthly and annual times scales in Iran using four different versions of the Mann-Kendall method: i) conventional Mann-Kendall method (MK1); ii) Mann-Kendall method following removing the effect of significant lag-1 auto-correlation (MK2); ...
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The aim of this study is the analysis of surface wind speed in monthly and annual times scales in Iran using four different versions of the Mann-Kendall method: i) conventional Mann-Kendall method (MK1); ii) Mann-Kendall method following removing the effect of significant lag-1 auto-correlation (MK2); iii) Mann-Kendall method after the removing the effect of all significant auto-correlation coefficients (MK3); and Mann-Kendall method with considering the Hurst coefficient (MK4). Data used here are wind speed records in both monthly and annual time scales in the period of 1966-2005. For this purpose, 22 stations were selected across Iran’s area. Nonparametric Sen’s method was used for estimation of wind trend line slope. Results showed that although a combination of positive and negative trends observed both in monthly and annual time scales, however, the number of stations having the negative trends were more than that of the positive trends. In the annual time scale, the strongest negative trend line slope was -0.074 ms-1y-1 belonging to Fasa station, and the strongest positive trend line slope was 0.141 ms-1y-1 belonging to Zabol station. In monthly time scale, the strongest negative trend line slope was -0.1 ms-1y-1 observed in Fasa station and the the strongest positive trend line slope was 0.18 ms-1y-1 observed in Zabol station. Results showed that the median of the trend line slopes for all months (except February and November) was negative. Therefore, in general, it can be concluded that in the most of stations in Iran wind speed trend in all months (except February and November) was negative.
