Climatology
Yousef Ghavidel Rahimi; Manuchehr Farajzadeh; masood salehian
Abstract
Nowadays, Climate change is a hot topic engaging the scientists around the world as a cause for future human and environmental crises. It has been generally accepted that the main cause for climate change should be increases in the content of atmospheric carbon dioxide due to excessive burning of fossil ...
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Nowadays, Climate change is a hot topic engaging the scientists around the world as a cause for future human and environmental crises. It has been generally accepted that the main cause for climate change should be increases in the content of atmospheric carbon dioxide due to excessive burning of fossil fuels, esp. in industrial countries. In the 19th century, scientists realized that gases in the atmosphere cause a "greenhouse effect" which affects the planet's temperature. These scientists were interested chiefly in the possibility that a lower level of carbon dioxide gas might explain the ice ages of the distant past. At the turn of the century, Svante Arrhenius calculated that emissions from human industry might someday bring a global warming. Other scientists dismissed his idea as faulty. In 1938, G.S. Callendar argued that the level of carbon dioxide was climbing and raising global temperature, but most scientists found his arguments implausible. It was almost by chance that a few researchers in the 1950s discovered that global warming truly was possible. In the early 1960s, C.D. Keeling measured the level of carbon dioxide in the atmosphere: it was rising fast. Researchers began to take an interest, struggling to understand how the level of carbon dioxide had changed in the past, and how the level was influenced by chemical and biological forces. They found that the gas plays a crucial role in climate change, so that the rising level could gravely affect our future.
Yousef Gavidelrahimi; Manochehr Farajzadehasl; Mehdi Alijahan
Abstract
Today, global warming effects on various aspects of the Earth are no secret to anyone. Because of this, the research ahead is done for the detection of global warming on minimum temperatures, monthly and periodic (hot and cold) as well. For this study, two groups of data, temperature data of 17 synoptic ...
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Today, global warming effects on various aspects of the Earth are no secret to anyone. Because of this, the research ahead is done for the detection of global warming on minimum temperatures, monthly and periodic (hot and cold) as well. For this study, two groups of data, temperature data of 17 synoptic stations and corresponding amounts of data in global temperature anomalies were figured out over 60 years period of time (1951 to 2010). Goals, the Pearson correlation method for detecting relationships between data, linear and polynomial regression for trend analysis time series data , To illustrate the correlation between the spatial distribution of temperature data with global warming stations nationwide Geostatistical model Finally, non-parametric test for detecting significant temperature change Man - Kendall were used. Based on the results, apart from Khorramabad and urmia stations that have negative relation with global warming and Hamadan and Kerman stations that do not show any significant relationship with global warming, global warming is seen as a positive influence on the other stations. Caspian Bank stations than any other stations in the cold months of global warming have much more influence. Checking the changes of minimum temperature trend showed a significant change in several months. In the warm months the maximum temperature variability is seen in the southern stations of Ahwaz, Abadan, Bushehr and Shiraz. Results obtained from the survey period (hot and cold) minimum temperature, indicate a greater influence global temperature anomaly on the minimum temperatures are warm period of year. During the warm period, southern stations have had the highest influence on the station and during the cold period Caspian Bank stations have had the highest relationship with it. The changes were made based on both periods the obtained results are clarity significant.
Climatology
Yousef Ghavidel Rahimi; Manochehr Farajzadeh Asl; Daryoush Hatami Zarneh
Volume 20, Issue 56 , August 2016, , Pages 239-255
Abstract
The NCP as one of the effective teleconnection patterns in level of 500 hpa have an important role in thermal and hydro-climatic variability in East Mediterranean region. In this study to investigate the correlation between the NCP and maximum temperature fluctuations Iran for a 60 years period (1950-2010) ...
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The NCP as one of the effective teleconnection patterns in level of 500 hpa have an important role in thermal and hydro-climatic variability in East Mediterranean region. In this study to investigate the correlation between the NCP and maximum temperature fluctuations Iran for a 60 years period (1950-2010) have been studied. Pearson correlation analysis as the main method used in this study show an inverse relationship between maximum temperatures and selected stations and NCP index. This shows decrease of temperature in positive phase of the NCP and rise of temperature in negative phase. In terms of time correlation coefficients were calculated and showed a significant negative correlation between the temperature of stations and the NCP in months of January, February, March and almost direct relation most stations in August. At monthly interval in the monthly correlation between stations with 0.342 were computed in January. Seasonal correlation of shows a significant correlation of maximum temperatures in winter to be -0.212. In terms of period, the results indicate a strong correlation between cold period in most stations and mentioned index. Atmospheric circulation in 500 hpa at positive and negative phases showed in positive phase, settlement of deep trough on the Caspian Sea, Iraq, Turkey and Iran, and also the location of Iran in the eastern part of the trough axis on the other hand, indicates establishment of a ridge on the North Sea and Europe which leads to transfer of cold temperatures of northern Europe and its adjacence of polar section to Iran. But on the negative phase placement of Iran beneath the ridge axis leads to the creation of a barotropic atmosphere with weak zonal wind and warm temperatures to Iran. So with blowing warm air from Africa, Arabia and low latitude Iran's temperature rises.
Manochehr Farajzadeh; Saeed Rajaee Najafabadi
Volume 17, Issue 45 , November 2013, , Pages 142-162
Abstract
In this paper we study the heavy precipitation and probability of occurring flood as a result of it for Koohrang station. The synoptic and discharge maps were chosen and drawn in purpose of showing the discharge peak for 29 February by175 mm rainfall. In this day a low pressure center was located in ...
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In this paper we study the heavy precipitation and probability of occurring flood as a result of it for Koohrang station. The synoptic and discharge maps were chosen and drawn in purpose of showing the discharge peak for 29 February by175 mm rainfall. In this day a low pressure center was located in Greek. As this center expanded to the north, the thermal low pressure above the Sudan and Saudi Arabia became dynamic and stretched toward the west of Iran. According to the sea surface, 500 mb and moisture flow, this heavy rainfall was the result of the instability from surface to 500 geopotential levels and generated 5.7 m2/s discharges in the regain.
