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.
Mohsen Aghayariehir; Migat Habibyan; Mehdi Ostadiejafari; Hamed Aminishirazi
Volume 19, Issue 53 , September 2015, , Pages 25-47
Abstract
Nowadays, while there are a number of definitions have been introduced for the concept of zoning, there is no general consensus due to different disciplines adopt this term. In the field of planning, the zoning is a conscious and contemplative process to detect homogenous areas by an authority to allocate ...
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Nowadays, while there are a number of definitions have been introduced for the concept of zoning, there is no general consensus due to different disciplines adopt this term. In the field of planning, the zoning is a conscious and contemplative process to detect homogenous areas by an authority to allocate certain kinds of resources to them. Therefore, the process of zoning is an essential task to allocate and monitor the development projects for different type of territories. In this article, zoning is took into consideration from the rural transportation point of view to find what would be the homogeneous zones of rural transportation for Iran? To answer this question, an in-depth spatial analysis through the Geographical Information System (GIS) is performed with regards to a descriptive-analytical method. Based on four main indices which are fully explored in the paper (i.e., access to the link road, distance to urban hierarchical levels, rural density and land use), five homogenous distinct zones for Iran is emerged. The resulted zones which are presented on a country map would be useful for future rural transportation planning in Iran.
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
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.
Volume 16, Issue 41 , November 2012, , Pages 237-250
Abstract
Ozone is a very small part of earth atmosphere, but its presence is nevertheless vital to human well-being. Most ozone resides in the upper part of the atmosphere. This region called the stratosphere is more than 10 kilometers above earth's surface. About 90 percent atmospheric ozone is contained in ...
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Ozone is a very small part of earth atmosphere, but its presence is nevertheless vital to human well-being. Most ozone resides in the upper part of the atmosphere. This region called the stratosphere is more than 10 kilometers above earth's surface. About 90 percent atmospheric ozone is contained in the ozone layer or ozonosphere which shields every living thing from ultraviolet light from the sun. Total ozone is all the ozone in the atmosphere. Total ozone values often report in Dobson units. Typical values vary between 200 to 500 Dobson over the globe. Total ozone varies strongly with spatial (latitude) and temporal over the planet. This paper with using different statistical as regression analysis, variance analysis and Student-Newman-Keuls (SNK) methods tried to discover the relationship between total ozone and time variation in monthly, seasonal and annual time scale in Isfahan ozone metric station. Analysis of variance shows significant different between time series means p<0.01. The best series agreement with the among of ozone is seasonal series so that average of among of ozone shows a significant in each season with S.N.K test but monthly and yearly mean of ozone don't show significant difference in all of months and years . Spring has the maximum of seasonal mean of ozone and fall has the minimum of it. Results of study on trend indicate a no significant trend in the annual mean in the time series.
Karim Hosainzadeh Dalir; Mohammadreza Pourmohammadi; Seyed Majid Seyed Fatemi
Volume 16, Issue 38 , February 2012, , Pages 1-18
Abstract
In different countries, new towns are constructed based on necessity and their functions. Nowadays, making new towns is not of course performed with the aim of realizing the notion of ideal habitation or Utopia, rather decentralization of large cities is its purpose and main goal. Nonetheless, this topic ...
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In different countries, new towns are constructed based on necessity and their functions. Nowadays, making new towns is not of course performed with the aim of realizing the notion of ideal habitation or Utopia, rather decentralization of large cities is its purpose and main goal. Nonetheless, this topic is differently viewed in Iran in comparison with other countries, and its utility and function in Iran is not the same as the real purpose of making new towns in the world. This article studies the country’s population variations in recent decades and considers urban system of the country. It also analyzes the activities of new towns in recent years and eventually argues the necessity to make new towns in Iran. The agreement of this strategy with alternative ones, especially with the strategy of middle cities reinforcement, is argued as well.
Masood Goodarzi; Saeed Jahanbakhsh Asl; Majid Rezaee Banafsheh
Volume 16, Issue 37 , November 2011, , Pages 133-149
Abstract
Flood risk estimation is one of the most important subjects for hydrologists and other scientists. The main objective of flood risk estimation is to study the past events in order to foresee the future flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations ...
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Flood risk estimation is one of the most important subjects for hydrologists and other scientists. The main objective of flood risk estimation is to study the past events in order to foresee the future flood risk. There are various methods for flood risk estimation. Rainfall- runoff and empirical equations are among the most used methods. In these methods, rainfall is the main parameter influencing flood mechanism. In this research, spatial distribution of rainfall pattern in Esfahan province is studied. Esfahan province with 10.5 million hectars of area has located in the central part of Iran with different topography, climate and ecological condition. Over 203 rain-guages located in the study area and its neibourhood were studied. The duration base of data record was 33 years. A total of 1654 storm events with less than 1 hour to 72 hours duration were considered, in which three index events, i.e. widespread and maximum events were used. The common methods of geostatistics, Krigging, Co-Krigging, IDW and TPSS were applied to interpolate the recorded points to non-observed ones. Among the studied interpolating methods, Krigging shows the best results, from which the Gussian and spherical models best fits to the observed points. In order to gain the best results, it is recommended to add the number of rainfall guage sites according to the World Meteorological Organization (WMO) standards. Also, we propose grouping the study area into homogeneous regions and studying DAD in each homogeneous region is advised.
