Showing 5 results for Mean
Yosouf Ghavidel Rahimi, Manochehr Farajzadeh, Mehdi Alijahan,
Volume 15, Issue 36 (6-2015)
Abstract
Global warming and the meaningful relationship between temperature and precipitation changes over different areas of the earth with temperature increment of the earth, are considered as the most important patterns of this century’s climate changes. Today, there is debate over climate change and global temperatures increasing. Damaging effects of this phenomenon on the planet is one of the most challenging issues in global scale. Because of this, the research ahead is done for the detection of global warming on maximum 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's, 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. According to the results impact of global warming on the maximum temperature in the cold months like January, December and November should be much lower, and the highest in spring and summer season in the southern stations such as Abadan, Ahwaz and Shiraz seen. The above process is also evident in periods of hot and cold temperatures and the influence of the stations temperature of the warm period of global warming were higher than cold period and represent an increase in the temperature of the warm period of years. In between, the number of stations as well as Anzali, Urmia and Khorramabad stations in some months had the opposite influence of global warming and seen drop in the maximum temperatures of them. It is also observed in the results obtained from the analysis period. Station's maximum temperature trend change is represents significant in the summer month. Changes trend in the months of July, August and September, is significant that the process is more pronounced in the southern stations. Significant analysis trend changes have been taken in periods (cold and hot) in studied stations indicative of its significance in warm period.
Hosseinali Roohbakhsh Sigaroodi, Mostafa Karampoor, Hooshang Ghaemi, Mohammad Moradi, Majid Azadi,
Volume 19, Issue 55 (12-2019)
Abstract
Investigating the variability of the spatial-temporal pattern of rainfall, which can lead to climate change, due to its strong impact, is of interest to various scientists. For this purpose, after receiving the daily precipitation data of 27 stations for the period of 60 years (2010-1951), its quality and the total monthly precipitation and statistics necessary for the continuation of the research process such as mean, coefficient of variation, skewness, probability estimate of 20% The upper limit of the maximum and minimum rainfall average were calculated experimentally for a period of 60 years and two 30-year periods (1951-1980 and 1981-2010) and two periods of 10 years (1951-1960 and 2010-2001) for each of the spring and summer seasons Was calculated. The studies show relatively modest variations in spring and summer precipitation patterns on the Caspian coast, Northwest-West, 30 and 10 years old, compared to the 60-year, 30-year, and 10-year periods. In general, the mean of precipitation decreases from north and northwest to south and south east and increases the amount of coefficient of change and skidding. Except for the Caspian Basin, in the remaining stations, the average spring precipitation is higher than the average summer rainfall. There is a clear difference in the long-term characteristics of precipitation and its changes. It is worth mentioning that the increase in the coefficient of variation of the 30-year and 10-year periods is comparable to the corresponding periods at all stations, which indicates a decrease in the monthly and seasonal mean of spring and summer precipitation, which confirms the results of the decade and the first decade of the second decade. The greatest decrease occurred in the northern and western parts. In the second 30 years, the incidence of dry sunshine and drought-affected stations has increased. Therefore, it confirms the climate change for the Caspian and the Southwest coast.
Dr Elham Hatami Golzari, Dr Ahmad Mirza Kouchak Khoshnevis, Dr Qader Bayzidi, Dr Foad Habibi,
Volume 21, Issue 60 (3-2021)
Abstract
Persistent spaces and phenomena over time and load and become part of collective memories. In this way, paying attention to the durability of space design increases the sense of belonging to space, in this case space does not belong only to the present. Considering the importance of sustainability, the purpose of this study is to identify the factors affecting the survival of urban spaces, with emphasis on the multiplication of effective daily life in three areas of the Tabriz market (Grand mosque, Rasteh bazar, and Saheb-ol-amr square). The research method is a descriptive-analytic study used for collecting information using documentary and field (survey) method. Also, in this research, in addition to applying the qualitative method for analyzing the causes of durability in the studied areas, quantitative method of analysis of variance was used to investigate the durability of urban spaces in the studied areas. The findings of the research indicate that within the boundaries of the Grand mosque, the spirituality factor (0.376), socioeconomic and functional (0.352), in the range of Rasteh bazar of the identity factor (0.314) and within the range of Saheb-ol-amr square, the factor of spirituality (0.327) and identity (0.305) is the most important reason for the survival of the studied areas. The results also show that the various components of everyday life have oddities that, while repeated in the daily life cycle, are linear (progressive, regressive, and fixed), which in two parts are all in part and in part In general, they affect the survival and decline of spaces. In the meantime, the approaches and cultural components derived from the whole are in part like the rituals and cultures of a community, have and will have a significant impact on the survival and increase of durability of spaces. Therefore, the continuation of rituals and cultural ceremonies in the studied areas can provide a lasting space for these spaces.
Dr Fariba Esfandyari-Darabad, Dr Raoof Mostafazadeh, Dr Ahmad Abyat, Ahmad Naseri,
Volume 21, Issue 61 (6-2021)
Abstract
Most of residential areas, population centers, and agricultural lands are located along the rivers and especially on the river terrace, which are affected by river dynamics, discharge changes, and flood hazards, bed fluctuations and meander variations. Therefore, it is necessary to study the behavior and pattern of meander movements of rivers in order to avoid potential hazards. The current research conducted in a reach of Gharehsou River in Ardebil province and the field measurements were done at adjacent to Anzab village to the Samian Bridge.
In order to determine the pattern of this river, the Leopold Sinuosity Factor and the central angle calculated using Cornice method were used in this study. The results showed that the average of the Sinuosity Factor in the study area was 1.47, Which indicates the high ratio of river sinuosity. It also indicates the spatial variation of meanders evolution is not the same over the studied reach. The values of obtained Sinuosity factor using the employed methods showed that the %71.11 of meanders (32 meanders) with sinuosity factor of 1-1.5 belong to the category of low meander degree. While, the %17.78 of meanders (8 Meanders) had the sinuosity factor of 1.5-2. The remained 5 meanders (%11.11 of the identified meanders) had the sinuosity values greater than 2. This means that there are at least 5 meanders in the study area that are susceptible to becoming an oxbow-lake. Therefore, it is necessary to stabilize the stream banks and river bed of the study reach through structural management and engineering methods.
Sayed Hedayat Sheikh Ghaderi, Abdulsalam aminpour, Parviz Ziaeian Firoozabadi,
Volume 24, Issue 72 (6-2024)
Abstract
Corona and Hexagon satellite photographs with a spatial resolution of 1.8 to 9 meters are a good source for monitoring and evaluating changes in surface phenomena. The purpose of this study is to monitor the changes in Zaribar Lake in the period 1969-2019 using the data of Corona, Hexagon and Aster satellites and their ability to monitor and extract the coastline, lake boundary and water surface. In this study, to geometric correction the corona and hexagon data from Google Earth images, linear extraction algorithms, binary mask and mean shift segmentation were used to extract the coastline and lake boundary, detect lake changes and extract and monitor the water area of Zaribar Lake. The results showed that in the first step: geometric correction of corona and hexagon images was obtained using Google Earth images with RMSE of 0.3 and 0.4 pixels. In the second stage, the linear extraction algorithm for extracting the lake boundary and coastline using corona and hexagon photographs has high accuracy and has a high correlation with the topographic map of 1.50000. In the third step, the unsupervised classification of binary mask method, in order to detect lake changes using corona and hexagon photographs, acceptablely identified the altered and unchanged pixels, so that 11 hectares of lake surface had the most changes. Finally, in the fourth step, it was found that the mean shift segmentation algorithm and threshold worked better by applying the corona, hexagon, and Aster events to extract the water surface, and in the meantime, the corona image performed better due to its higher resolution. The above results showed that Zaribar Lake decreased by 6.5% from 1969 to 2019 and the findings have a high correlation with the product of the ester aquifer. In general, the findings of this study show the potential of using digital image processing methods for corona and hexagon data to monitor and detect changes in lakes.
