Faramarz Khoshakhlagh; Nemat Ahmadi; Mostafa Karimi
Abstract
Introduction The notion of climate change indicates a significant change in climate and environmental conditions over a long period of time (from a few decades to centuries). These changes can occur in mean radiation, temperature, precipitation, atmospheric patterns, wind, and other climate parameters. ...
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Introduction The notion of climate change indicates a significant change in climate and environmental conditions over a long period of time (from a few decades to centuries). These changes can occur in mean radiation, temperature, precipitation, atmospheric patterns, wind, and other climate parameters. Increased global average temperature and occurrence of climate extremes such as floods, storms, hails, tropical storms, heat waves, sea level rise and melting of polar ice caps are the most important effect of climate change. The present study sought to analyze the effect of climate change and global warming on temperature trends in Iran atmospheric levels. One advantage of the present study is that it investigates temperature changes at sea surface and other atmospheric levels, whereas many recent researches just emphasize on sea level. Materials and methods The present study used data received from the European Center for Medium-range Weather Forecast (ECMWF) for a period of 60 years, from 1951 to 2010, with a network resolution of 1 × 1° Latitude and Longitude for sea level data (Slp) and 850, 700 and 500 hPa levels. After converting extracted data using statistical extension of Net-cdf for excel 2007, the temperature trend for sea levels of 850, 700 and 500 hPa were calculated. The correlation between temperature and its anomalies was measured using elevation levels of 850, 700 and 500 hPa and the temperature anomaly maps and synoptic pattern were developed on a regional scale, and finally their relationship with temperature trends were analyzed and interpreted. Results and Discussion Iran had an average temperature of 18.06 °C during the 60 year period (1951 to 2010). 1999, with an average temperature of 20 C°, was the hottest year during this time. From 1993 onwards (except for 1997 and 2007), the average temperature was more than the 60-year average (18.06 C°). By comparing 30-year periods (from 1951 to 1980 and from 1981 to 2010) with each other, we observed that sea level temperature increase in the second 30-year period was more than the first period temperature increase at other atmospheric levels. This increase is most possibly due to the effects of global warming. Temperature increase in the first and second periods were 0.24 and 0.63 °C, respectively. Because of closeness to sea level and under the influence of surface conditions, 850 hPa level shows maximum temperature increase compared to other atmospheric levels (after sea level). Also due to the impact of sea level during the first and second periods, this factor is highly correlated with the sea level atmospheric condition. Despite the fact that correlation values of 850, 700 and 500 hPa levels were significant in both first and second periods at 1% level, they have increased in second period at all atmospheric levels. In other words, there is a clear increasing trend in the second period and few decreasing changes are observed. Regarding the patterns observed at sea level in the second period, two low-pressure closed cell trough which had been observed in the first period in India and Pakistan, merged in the second period. At 850 hPa, the subtropical high pressure located over Atlantic in the first period moved to East Africa in the second period and created a closed high pressure subtropical cell over Libya with an elevation of 1500 hPa. Compared to the first period, this high pressure cell has a higher altitude. At 700 hPa level, STHP ridge extended significantly in the second period, and in this period, central regions of Iran exhibit wide ranges of air sinking with a deep layer of warm air. Conclusion Over the 60 year-period, temperature of atmospheric levels in Iran have exhibited an increasing trend, which from 1993 onwards had a much steeper slope of increase. Compared to the first period (with almost normal periods of increasing and decreasing, and a slightly fluctuating rhythm), the second thirty-year period is expected to exhibit a constant and continuous increase. Additionally, warmer SLP at sea level and 850 hPa level, the northward expansion of the Hadley cell, and finally more intense subsidence of STHP toward lower atmospheric levels (above sea level and 850 hPa) exacerbate the effects of global warming on Iran atmosphere.
Hossein Mohammadi Hossein Mohammadi; Ghasem Azizi; Faramarz Khoshakhlagh; Mahdi Khazaei
Abstract
Abstract
Accurate and timely estimation of evapotranspiration has a significant and critical impact on the planning of water resources and agriculture. In this research, the estimation of evapotranspiration of sugarcane in Khuzestan province has been studied, and the data used, have been air temperature, ...
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Abstract
Accurate and timely estimation of evapotranspiration has a significant and critical impact on the planning of water resources and agriculture. In this research, the estimation of evapotranspiration of sugarcane in Khuzestan province has been studied, and the data used, have been air temperature, relative humidity, wind speed and sunny hours since the establishment of synoptic station until 2014. For this purpose, the evapotranspiration values of the reference plant were first calculated using the FAO Penman-Monteith standard method and then, using available plant coefficients, the amount of sugarcane evapotranspiration was estimated at different stages of growth. The results of this study show that the average sugarcane evapotranspiration in Khuzestan province has been 3.35 mm / day in June and in the early stages of growth, 10.46 mm/day in the middle stages of growth, and 6.26 mm / day in the final stages of growth. The value of this parameter in July was estimated 3.59 mm/day in the early stages, 11.23 mm/day in the middle stages and 6.74 mm/day in the final stages of growth. Finally, the amount of evapotranspiration of sugarcane in August was estimated 3.56 mm per day in the early stages of growth, 11.12 mm/day in the middle stages and 6.67mm per day in the final stages of the growth. The maximum daily and monthly evapotranspiration has occurred in July and the minimum in June. Also, the highest daily and monthly fluctuations of sugarcane evapotranspiration have occurred in the middle stages of growth and the lowest in the early stages of growth.
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; Mohsen Soltani
Volume 20, Issue 78 , August 2011, , Pages 32-38
Abstract
One of the main pillars of agricultural planning is the identification of agricultural climatic units. An agricultural climatic unit is a unit in which the ground features and climatic elements are considered as integrated units, and each unit can have different characteristics. In this regard, the condition ...
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One of the main pillars of agricultural planning is the identification of agricultural climatic units. An agricultural climatic unit is a unit in which the ground features and climatic elements are considered as integrated units, and each unit can have different characteristics. In this regard, the condition of Sari station was considered as a sample strawberry cultivating area in Mazandaran province. For this purpose, climatic and environmental data and statistics of Mazandaran province were collected in terms of layers of ground and climatic factors and evaluated using Excel software. GIS software (1) has been used to draw up climatic and descriptive maps of the province. From ground factors, topographic layers, land use, slope and type of soil and from climatic elements, precipitation and annual temperature are considered. Using the special functions of the GIS system, first a weighted value was given to the layers according to the potentials of strawberry cultivation, and then they were combined in a final map. The final map indicates the ability of different regions of Mazandaran province to grow strawberries. The results indicate the accuracy of the map and the ability of the GIS to help provide an integrated analysis and homogeneous agricultural climatic units.
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.
Ja'far Ma'soumpour; Faramarz Khoshakhlagh
Volume 18, Issue 71 , November 2009, , Pages 26-30
Abstract
It is generally accepted that climate is one of the main sources of tourism in a region. However, it is assumed that its role in determining the region's potential for tourism is obvious. In a more general statement there is relatively little knowledge about the effects of climate on tourism or the role ...
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It is generally accepted that climate is one of the main sources of tourism in a region. However, it is assumed that its role in determining the region's potential for tourism is obvious. In a more general statement there is relatively little knowledge about the effects of climate on tourism or the role it plays. In addition, there is little information about the economic impact or the importance of the climate on the outlook of tourism business. In all areas with climatic criteria, people are accustomed to deciding on tourism and recreation, but often without research and highly relevant to types of applications. So far, much of the research, especially on climate, which is presented in scientific journals, has superficially dealt with the links between climate and tourism instead of conducting scientific observation. In addition, it seriously lacks any organized conceptual framework or a frame that contains interactions, processes, patterns, and theories. These theoretical frameworks are very important because they are bases for producing data, testing hypotheses, and developing further theories. Without these, it is difficult to expand a series of related research methods, and perhaps more importantly, to strengthen the development of patterns that bridge between theoretical and practical levels and can help form a relevant basic knowledge for understanding, expression and prediction. This paper examines the work done on climate and tourism so far with a comparative look at the theoretical and conceptual frameworks, and considers the courses of action that may result from combination of these methods in the future.
Faramarz Khosh Akhlagh; Gholamreza Rowshan; Reza Borna
Volume 17, Issue 67 , October 2008, , Pages 75-80
Abstract
In this study, using 33-year statistics (1970 - 2003) concerning radiation, cloud density and wind parameters, the study of the feasibility of establishing solar power plants in arid regions of Iran has been conducted. Further, considering the station of Yazd as the most suitable geographic location ...
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In this study, using 33-year statistics (1970 - 2003) concerning radiation, cloud density and wind parameters, the study of the feasibility of establishing solar power plants in arid regions of Iran has been conducted. Further, considering the station of Yazd as the most suitable geographic location for the establishment of solar power plant, stations in its adjacent regions such as Isfahan, Kerman, and Zahedan have been compared in terms of radiation regime and other climatic elements effective in the establishment of solar power plant. After identifying the climatic variations of the stations, and next, the use of statistical methods of standard deviation, coefficient of variation, T-test and ..., Isfahan was introduced as the station most similar to that of Yazd for the establishment of solar power plant.
Ruhallah Owji; Faramarz Khosh Akhlagh
Volume 16, Issue 61 , May 2007, , Pages 39-42
Abstract
One of the main characteristics of the Earth's system is climate change on short and long time-scales which imposes fluctuations in climatic parameters such as temperature and precipitation. These fluctuations are severe in some parts of the world and cause disturbances in natural ecosystems. Drought ...
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One of the main characteristics of the Earth's system is climate change on short and long time-scales which imposes fluctuations in climatic parameters such as temperature and precipitation. These fluctuations are severe in some parts of the world and cause disturbances in natural ecosystems. Drought is a climate fluctuation that affects many of the arid and semi-arid regions of the world with different intensity. The mountainous region of the west of Iran has severe precipitation fluctuations due to having a semi-arid to semi-humid climate regime, which causes increasing damage in years of drought. In this research, air temperature and rainfall variations in the Middle-west region of Iran were determined using statistical methods and data from synoptic stations in Arak, Ilam, Khorramabad, Zanjan, Sanandaj, Kermanshah and Hamedan, and the frequency of dry and wet years and the statistical relationship between the two phenomena were studied and evaluated. Statistical calculations were made on the monthly and annual rainfall and temperature data of the studied stations. Moreover, according to the results, it seems that on average a four-year fluctuation is predominant in the precipitation regime of the region, and the trend of precipitation changes indicate regular fluctuations in dry and wet years.
Faramarz Khosh Akhlagh; Gholamreza Roshan
Volume 15, Issue 57 , May 2006, , Pages 42-46
Abstract
In this paper, drought in three stations in Fars province has been investigated based on the three indicators of SIAP, PNPI and RAI. After calculating the coefficients of drought indices for the three stations, considering the growth rate of the indices, the coefficient of variation, correlation and ...
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In this paper, drought in three stations in Fars province has been investigated based on the three indicators of SIAP, PNPI and RAI. After calculating the coefficients of drought indices for the three stations, considering the growth rate of the indices, the coefficient of variation, correlation and trend rate of the indices, each of the indices has been compared among the stations, and each of the indices is evaluated at the stations. The results of the growth rate showed that there is a close relationship between the growth rate of the SIAP and the PNPI indices in Shiraz station and between the PNPI and RAI indices in Abadeh station. Regarding the dispersion coefficient, it can be stated that the least dispersion is in the RAI index in the Abadeh station. But the lowest dispersion in the SIAP and PNPI indicators are in Shiraz Station. Regarding the coefficient of correlation among the indicators and the statistical period, the situation is the same, so that the highest correlation is between the RAI index and the years in question at Abadeh station. However, the highest correlation exists between SIAP and PNPI indices with the years of statistical period in Shiraz station. Finally, the results of the general trend of the indices in the three stations are relatively the same.
