فهرست مطالب نویسنده:
naeim mijani
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بررسی تاثیر گسترش فیزیکی شهر بر تغییرات طبقات دمایی و تاثیر حرارتی اراضی ساخته شده و غیر ساخته شده بر یکدیگر در بسیاری از مسایل محیط زیستی از جمله نگرانی های مربوط به مصرف انرژی، دغدغه برای ایجاد محیط های شهری با کیفیت تر و توسعه ی شهری پایدار کاربرد دارد. هدف از این پژوهش بررسی تاثیر گسترش فیزیکی شهر بر تغییرات طبقات دمایی و تاثیر حرارتی اراضی ساخته شده و غیرساخته شده بر یکدیگر می باشد. برای این منظور در این پژوهش از تصاویر چند زمانه لندست، محصول بخار آب مودیس و داده های زمینی شهر بابل و حومه آن برای تابستان سال های 1364، 1371، 1379، 1387 و 1394 استفاده شده است. برای طبقه بندی کاربری اراضی و محاسبه دمای سطح به ترتیب الگوریتم های بیشترین شباهت و تک کاناله بکار گرفته شده است. نتایج پژوهش نشان داد که دمای سطح اراضی فضای سبز و زراعی با کاهش فاصله از اراضی ساخته شده افزایش می یابد. اراضی ساخته شده بر روی دمای سطح اراضی اطراف خود تاثیر مستقیم گذاشته و اراضی غیرساخته شده واقع در طبقه دمایی بالاتر به نسبت طبقه دمایی پایین تر در میانگین فاصله نزدیکتر به اراضی ساخته شده قرار می گیرند. نتایج پژوهش نشان دهنده تاثیر حرارتی اراضی ساخته شده و غیر ساخته-شده بر یکدیگر تاثیر می باشد.کلید واژگان: تغییرات, اراضی ساخته شده, اراضی غیر ساخته شده, تاثیر حرارتی, اثرات محیط زیستیIntroductionIn the last decades, the earth’s surface has experienced various changes due to some obscure reason being caused by human activities consisting of deforestation and cities expansion. These widespread human changes pose several adverse problems. For instance, an environmental qualitative decrease which culminates in the reduction of living quality is the result of these adverse changes. Warming of the urban environment owing to oblivious effects of unstable urban expansion, replacing of natural land cover with urbanization phenomena, inter alia, pavements, buildings, concrete and other urban constructions, are discerned as the main factors of creating heat island, which cause the vanishing of land surface cooling effects. Moreover, skyscrapers and narrow streets diminish the airflow and give rise to an increase in the environment temperature. The remote sensing images are known as an appropriate information source for preparing heat maps and also benefiting from widespread applications for the precise investigation of climate changes and urban and non-urban land use changes, due to the continuous and extensive coverage, timeliness and the ability to acquire information in the reflective and thermal range of electromagnetic waves. The population of Babol city steadily increase as a result of population growth and villagers’ emigration and bring about excessive and unplanned constructions, alteration in the physical model of the city and finally expansion of the city in various directions. Physical expansion leads to numerous changes in urban land use and suburbs agricultural uses. Consequently, several serious problems occur including adversity in uses, the urban environment disorder as well as the vanishing of suburbs agricultural lands and their land use change into urban uses (residential, industrial and etc.). One of the adverse effects of urban physical expansion, declining of green space and changing of agricultural land use into the urban land use is the rise in the surface temperature. The aim of this study was to investigate the effects of Babol city expansion on changes in temperature classes and the thermal effects of built-up and non-built-up lands on each other during the period of 1985-2015.Materials & MethodsFor this purpose, multi-temporal Landsat images were used in this study. For calculating the land surface temperature, ingle channel algorithm were used, and Maximum likelihood algorithm was also applied to classify images. Therefore, land use changes and land surface temperatures (LST) were examined, and thereby the relationship between land-use changes was analyzed with the land surface temperature. Surface temperature changes map for the period of 1985-2015 was prepared and analyzed regarding land use changes map for the study area to investigate the effects of land use changes on surface temperatures changes. By using the mean and standard deviation of normalized thermal images, the area was divided into three thermal classes. The status of each land use in the specified thermal classes and the impact of surface temperature in built-up and non-built-up lands on each other were investigated.Results & DiscussionThe results indicate that most land use changes in the studied area belong to the change of agricultural and green space uses into built-up use in suburbs, which are 740.52 and 472.14 hectares, respectively. As it was shown through the findings, 92% rise was observed for the built-up use area. These changes are more significant in the periphery of the city. The use of green space has risen from 1656.55 hectares in 1985 to 2036.52 hectares in 2015, which shows an increase of 23 percent. The trend of growing the use of green space on the periphery of the city is clearly characterized by the conversion of agricultural land to citrus gardens. The growth of the use of green space is less than the growth rate of built-up use. The built-up use has experienced a significant growth trend over the study period, as area of built-up use has risen from 19% in 1985 to 52.52% of the area in the studied area in 2015. The results of the LST mean survey of land use types for the study area show that the built-up lands than the other lands have the highest LST for all years. Water lands have the lowest LST owing to the high water heat capacity. In most of the years, arable land has a lower LST mean than green space land, which is mainly due to the high moisture of the arable land and the greater activity of evapotranspiration. Most changes in surface temperature of the area are related to the distance of 0-800 meters of built-up area. The main reason could be the conversion of the agricultural and green space lands into the built-up lands in the area. The most prevalent temperature class in all years is the medium temperature class which covers the suburb lands. The hot temperature class is more highlighted in the center of the city, streets and ways out of the city. Although the adjacent of the city is covered by medium temperature class, cold temperature class are located far from the built-up urban area. Cold temperature class which follows a decreasing trend, is related to lands which are far away from the city. Also, hot temperature class at which the area increases annually, is adjacent to the city core and exit ways of the town. The highest temperature changes belong to areas which transformed from the other uses into built-up use during the past 30 years. Due to human activities which produce heat, the area which has remained in the form of built-up land use during this time period has had a noticeable temperature rise. Green space and agricultural areas which have not transformed into other land uses benefit from the least temperature changes during this time period. On account of growing of built-up land use, an increase has occurred in the area of hot temperature classes and a decrease in the area of cold temperature categories. Built-up lands have direct effect on their adjacent land surface temperature. The results of the survey with regard to arable lands and green space in different temperature classes indicate that the areas of green space and arable lands, located above the upper temperature, are proportional to areas of the land that are located in lower temperature classes and they are located in the average distance closer to the built-up lands. In other words, the green space and arable lands that are located closer to the built-up lands have higher temperature relative to the green space and arable lands which are far from the built-up lands. Also, green space lands which are located in urban environments have a higher temperature in proportion to the area of the green space lands adjacent the city owing to the high temperature of their surrounding areas. Green space lands in the urban environment, which have no high area, are more affected and classified into hot temperature classes. Built-up lands, which are located in the urban environment and adjacent to the green space, also has a lower average surface temperature than the green space, and sometimes located in the middle temperature class. This refers to the effect of moderating surface temperatures in built-up lands by green space lands.ConclusionsAs a result, non-built-up lands with higher temperature classes are in a lower average distance from built-up lands compared to those with lower temperature classes. Built-up lands in the adjacent agricultural and green space lands have lower surface temperature compared to other built-up lands. As a result, these lands are considered to be medium temperature class. The results of this study showed the importance of planning and management for preserving agricultural and green space lands and preventing them from being transformed into built-up lands which increases the surface temperature and negative environmental impacts.Keywords: Changes, built-up lands, non-built-up lands, thermal effects, environmental effects
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دمای سطح زمین (LST) برای انواع وسیعی از مطالعات علمی اقلیم شناسی، هیدرولوژی، منابع طبیعی و غیره مورد نیاز است. پارامترهای مختلفی ازجمله جنس مواد تشکیل دهنده سطح، شرایط توپوگرافی، شرایط محیطی و میزان تابش رسیده به سطح بر LST تاثیرگذار هستند. هدف از انجام پژوهش حاضر، بررسی تاثیر تغییرات توپوگرافی، شرایط اقلیمی و تابش ورودی بر LST با استفاده از داده های انعکاسی و حرارتی سنجش ازدور است. در این پژوهش از مجموعه داده های انعکاسی و حرارتی ماهواره لندست 8، مدل رقومی ارتفاعی ASTER، محصول بخارآب مودیس (MOD07) برای تاریخ 2 مرداد 1397 و نقشه توپوگرافی و اقلیمی منطقه جنوب استان کرمان استفاده شد. برای محاسبه LST از روش تک کاناله و جهت محاسبه تابش طول موج کوتاه و بلند ورودی به سطح، از روش ارائه شده در الگوریتم بیلان انرژی سبال استفاده شد. ارتباط بین LST با متغیر های مستقل ازجمله ارتفاع، شیب، جهت شیب، پوشش گیاهی و تابش ورودی به سطح با استفاده از تحلیل های آماری بررسی شد. نتایج نشان داد که ضریب همبستگی بین LST و هر یک از پارامترهای مستقل بیشتر از 0.7 می باشد. همچنین با بررسی های آماری، معنادار بودن نتایج ارتباط بین LST و پارامترهای توپوگرافی، شاخص اختلاف پوشش گیاهی نرمال شده (NDVI) و تابش ورودی در سطح 95 درصد معنادار بود. نتایج بررسی LST در شرایط اقلیمی فراخشک، خشک، نیمه خشک، مدیترانه ای، نیمه مرطوب و مرطوب بیانگر این است که اقلیم های با دمای بالاتر نسبت به اقلیم های با دمای پایین تر دارای میانگین ارتفاع و NDVI پایین تر و دارای میانگین تابش طول موج بلند ورودی به سطح بالاتری هستند.کلید واژگان: دمای سطح زمین, سنجش از دور, شاخص اختلاف پوشش گیاهی نرمال شده, شرایط اقلیمی, کرمانThe land surface temperature (LST) plays a vital role in a wide range of scientific researches including climatology, hydrology, natural resources and etc. There are some determining factors which affect the land surface temperature, such as the kind of surface elements, topography and environmental conditions and also the amount of incoming radiation to the surface. The objective of this study is to investigate the effect of topographic parameters, climatic conditions and downward radiation on land surface temperature using remote sensing data. For this purpose, the Landsat 8 satellite image, ASTER digital elevation model, MODIS water vapor product (MOD07) on 24 July 2018, topography and climate map of Kerman province were used. To calculate the LST and downward shortwave and longwave radiation to surface the single channel and SEBAL energy balance algorithms were used, respectively. Finally, using statistical analysis the relationship between LST and independent variables, including elevation, slope, aspect, vegetation cover index and downward radiation to the surface were studied. The results of the study shown that the correlation coefficient between the LST and each of the independent parameters is more than 0.7. Also, the relationship between LST and topographic, normalized difference vegetation index (NDVI) and downward radiation parameters at the 95% level was significant. The results of the mean of LST values in climatic conditions, including extra-dry, dry, semi-dry, Mediterranean, semi-wet and wet indicate that climates classes with higher LST relative to climates classes with lower LST have means of elevation, NDVI lower and mean longwave downward radiation to surface higher.Keywords: Land surface temperature (LST), Remote sensing, Normalized difference vegetation index (NDVI), Climate condition, Kerman
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مدلسازی ارتباط دمای سطح زمین، شرایط توپوگرافی، و پوشش گیاهی با استفاده از تصاویر ماهواره ای لندست 8دمای سطح زمین در طیف وسیعی از مطالعات محیطی کاربرد دارد. عوامل مختلفی از جمله جنس مواد تشکیلدهنده سطح و شرایط توپوگرافی و محیطی در دمای سطح زمین تاثیرگذار است. شناخت ارتباط بین دمای سطح زمین با عوامل فوق از اهمیت ویژهای برخوردار است. در پژوهش حاضر، با استفاده از تصاویر حرارتی سنجنده TIRS و با بهکارگیری الگوریتم پنجره مجزا، دمای سطح زمین محاسبه شد. سپس، ارتباط بین دمای سطح زمین با عوامل توپوگرافی از جمله ارتفاع، شیب، و جهت شیب و عامل پوشش گیاهی با استفاده از تحلیلهای آماری بررسی و معناداربودن روابط بهدستآمده در سطح اطمینان 95درصد تحلیل شد. بر اساس نتایج پژوهش حاضر، ارتفاع با دمای سطح دارای ارتباط معکوس است. پارامترهای شیب و جهت شیب در مدلسازی دمای سطح تاثیرگذارند. در بررسی ارتباط سطح و شرایط توپوگرافی، با درنظرگرفتن همزمان دو متغیر ارتفاع و شیب در جهت شیبهای خاص، بهعنوان متغیر مستقل، ارتباط قویتر شده است. همچنین، با اضافهکردن پارامتر شاخص پوشش گیاهی به پارامترهای مستقل، ضریب تعیین ارتباط بالاتر رفته است. رابطههای بهدستآمده در سطح معناداری 95درصد بررسی و آماره t حاصلشده برای ضرایب رابطهها معناداربودن ارتباط را تایید کردهاند.کلید واژگان: پوشش گیاهی, دمای سطح زمین, شرایط توپوگرافی, مدلسازیIntroductionland surface temperature plays a vital role in a wide range of scientific researches, inter alia, climatology, meteorology, hydrology, ecology, geology, medical sciences, design and optimization of transportation services, fire location and especially in calculating the real evaporation and transpiration. There are some determining factors which affect the land surface temperature, such as, the kind of surface elements, topography conditions, environmental conditions, climate condition and the amount of emitted energy from the sun. Recognition and analysis of the relation between the land surface temperature and various factors are so critical. The remote sensing method has a widespread application in preparing the land surface temperature images due to the extensive covering and continuous data. The purpose of this study was to investigate the effects of vegetation cover indices and topographic factors on land surface temperature and modeling the relationship between land surface temperature, topographic conditions and vegetation cover using Landsat 8 satellite imagery.Materials and MethodsIn this study, sensor reflective bands OLI, Jimenez and Sobrino method were utilized to calculate the emissivity of the available phenomena in the area. By using TIRS land set 8 sensor thermal bands 10 and 11 and utilizing Split-window algorithm, the land surface temperature was calculated. Topography parameters, such as elevation, slope and slope aspect and area vegetation were extracted using digital elevation model and NDVI index, respectively. Then, the relation between the land surface temperature and topography factors in diverse conditions was investigated by statistical analysis, and then, the validity of relations was analyzed with a confidence level of 95%. For this purpose, ENVI 5.3, Arc GIS 10.4, ERDAS IMAGING 2014 software as well as SPSS statistical software were used.Results and DiscussionThe obtained resultants indicate that the study area has a uniform vegetation cover in most areas and a high percentage of areas have the NDVI of 0.45-0.6. Nonetheless, due to the diversity in topographic and climatic conditions the area surface temperature is inhomogeneous and non-uniform. Consequently, there is no relation with a high correlation coefficient between the land surface temperature and vegetation in the area. However, there is a reverse linear relation between the land surface temperature and vegetation in the area. This relation gains a higher correlation coefficient in the form of linear relation compared to second order polynomial, Pearson, logarithmic etc. equations. Areas with southern and southeast slope have higher land surface average temperature compared to other directions during imaging due to their position which is in the direction of sun straight radiation. The temperature average is different in various slopes. Making the relation of temperature and elevation independent of slope parameters and slope aspect, give rise to an increase in the correlation coefficient between two parameters. The relation of the land surface temperature and elevation, regardless of slope and slope aspect for the studied area, is a reverse linear relation with the correlation coefficient of 0.54, whereas for the relation between the land surface temperature and elevation in the western slope direction and slope of 40-50 degree, there is a reverse linear relation with the correlation coefficient of 0.76. Moreover, in investigating the relation between the land surface temperature with topographic conditions, simultaneous consideration of both elevation and slope variables as independent variables for modeling the dependent variable of surface temperature lead to a strengthened relation. The addition of vegetation index parameter to relation independent parameters bring about a rise in relation’s correlation coefficient. For instance, relation’s correlation coefficient of the land surface temperature with elevation independent variables, slope, and vegetation in the western, northwest and southeast direction, are 0.84, 0.81 and 0.8, respectively. All the obtained relations are investigated in the confidence level of 95%, and validity of relations was confirmed by “t” statistic and resultant probe for relations’ coefficients.ConclusionResults imply that by considering each elevation, slope, slope aspect and NDVI parameters independently for modeling the land surface temperature, adverse results would be obtained, and by simultaneous using of both topographic parameters and vegetation and also their combination, as dependent parameters, the land surface temperature can be precisely calculated. In addition, for accurate modeling of the land surface temperature all topographic, climatic and environmental conditions for the area should be taken into account. The thermal and reflective remote sensing technology are economical, fast and effective due to several positive aspects such as providing uniform topographic, vegetation data and environmental parameters. So, further researches and investigation are necessary.Keywords: Vegetation cover, Land surface temperature, Topographic conditions, Modeling
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