Ali Hanafi
Volume 23, Issue 89 , May 2014, , Pages 67-71
Abstract
Weathering happens with the breaking and transformation of ground surface stones, due to physical, chemical or biological processes. Wind, water, climate, plant and animal factors can cause weathering. The present study is performed based on Louis Peltier models in which two variables of average temperature ...
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Weathering happens with the breaking and transformation of ground surface stones, due to physical, chemical or biological processes. Wind, water, climate, plant and animal factors can cause weathering. The present study is performed based on Louis Peltier models in which two variables of average temperature and precipitation were used. Applying these two variables, Peltier distinguished 7 models which can describe different forms of weathering. Among these, two models of weathering regimes and morphogenetic regimes were investigated in Iran and related regimes of each station were determined based on the related graphs. To study and investigate weathering and geomorphologic areas across the country, climatic data including average annual precipitation and temperature were collected from 143 stations in Meteorological Organization portal with appropriate data and statistical period. The collected data were registered in a GIS database. After investigating the temperature and precipitation trend of the country, the regime of each station was determined using Peltier models and a weight was assigned to it. Then, they were registered into the mentioned database and related maps were produced in Arcmap. Results indicate that 5 of 9 morphogenetic situations of Peltier models occur in Iran climatic situation, so the central plateau, east and west of the country are mostly located in arid zone. Mountainous areas, Zagros and Alborz elevations have semi-arid regime, and stations located in southern coasts of the Caspian Sea and western hillsides of Zagros have a mild regime. Regarding weathering, areas in the central plateau and southern part of the country have a very low level of weathering, mountainous areas like Zagros and Alborz elevations and North West of the country have a weak level of mechanical weathering. Some stations in Northern Alborz and western hillsides of Zagros have average chemical weathering with frost and in some stations on the southern coasts of the Caspian Sea, severe chemical weathering occur.
Ali Hanafi; Iraj Hatami
Volume 22, Issue 87 , November 2013, , Pages 24-28
Abstract
Climatic zoning and identifying influential factors and elements in each zone are considered to be the most important factor in environmental planning. Climatic research and climate map can be used in large, medium, small and local scales. Related researches in Kurdistan have been very limited. The present ...
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Climatic zoning and identifying influential factors and elements in each zone are considered to be the most important factor in environmental planning. Climatic research and climate map can be used in large, medium, small and local scales. Related researches in Kurdistan have been very limited. The present article investigates climatic features of Kurdistan province in a 30 year statistical period using weather stations and Information Technology System software. After qualitative and quantitate control of meteorological data and elimination of statistical deficiencies, two important climatic elements (temperature and precipitation) were investigated across the province. Afterwards, isothermal and isohyetal maps and the correlation between temperature and rainfall with altitude were produced using inverse distance weighting method. Conformity of temperature and rainfall with digital elevation model shows a significant inverse correlation between temperature, rainfall and altitude. So that with an increase in altitude, temperature and rainfall decreases. De Martonne and Embergent methods were used for climatic classification of the province. In De Martonne classification, Kurdistan province was divided into four climates, i.e. arid, Mediterranean, humid and very humid. Embergent method classified the area into four climates, i.e. cold semi-arid, highland climate, cold semi-humid and cold humid. Finally, zoning process was performed in GIS environment and inverse distance weighting method was used for spatial interpolation and spatial data analysis to produce Kurdistan climate map. Resulting zoning maps indicates that semi-arid and Mediterranean climate are dominant and only a small zone in the western parts has humid and semi-humid climate.
Mahdi Modiri; Zahra Alibakhshi; Faramarz Khoshakhlaq; Ali Hanafi
Volume 21, Issue 84 , February 2013, , Pages 7-20
Abstract
In order to recognize the effective synoptic system in creation of moderate and severe frosts in Tehran and the conditions under which sever and moderate storms transform into one another, synoptic analysis has been implemented by mean sea level 850 and 700 hp maps in a period of 45 years (1961-2005). ...
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In order to recognize the effective synoptic system in creation of moderate and severe frosts in Tehran and the conditions under which sever and moderate storms transform into one another, synoptic analysis has been implemented by mean sea level 850 and 700 hp maps in a period of 45 years (1961-2005). The synoptic results indicated that the transformation of moderate frost into severe and exterminator frost is because of cold weather advection from higher latitude, setting of through over region or earthly radiation. Surveying 850 hp maps, it was recognized that decreasing of temperature in research region arises from the cold advection of various systems from northwest to northeast. In mean sea level maps, extension of Siberian high pressure ridge, and in 700 hp level, setting of through over the eastern part of the district has the most frequency and share in moderate and severe frost formation.
Faramarz Khosh Akhlagh; Ali Hanafi; Saeed Ahmadi
Volume 19, Issue 74 , August 2010, , Pages 24-29
Abstract
Drought is one of the most important natural hazards that works in a slow and creeping way. This phenomenon is due to climatic processes, and its severity and frequency depend to a certain extent on the geographical position of the site, which happens every few years as a result of falling precipitation. ...
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Drought is one of the most important natural hazards that works in a slow and creeping way. This phenomenon is due to climatic processes, and its severity and frequency depend to a certain extent on the geographical position of the site, which happens every few years as a result of falling precipitation. In order to study and assess the droughts and wet years of Khoy station, the precipitation data of 32 years (1976-2007) were analyzed using standard distribution index and SPSS and Excel software, and it was found that the most severe drought in Khoy station has been in 1995 with an SPI coefficient of more than -1.6, and in 2001 with an SPI coefficient of more than -1.4, while its highest rate of wet year has happened in 1982 with an SPI coefficient of more than 2.8. Of noteworthy points about the continuity and sequence of droughts is the occurrence of severe droughts during the years 1995-2001 with varying degrees in this station. In order to predict the climatic condition of the Khoy station in the long run, the Markov chain model was used, which suggested that the probability of droughts was 43% and the probability of occurrence of wet years was 42.7%. In other cases, meaning 14.3% of the time, the normal condition of precipitation is prevailing. Similarly, the likelihood of droughts in the long run in winter, spring and autumn was estimated 41.8, 30.5 and 57.3 per cent, respectively.
