جستجوی مقالات مرتبط با کلیدواژه « دمای سطح زمین » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Investigating changes in vegetation density and land use is one of the most important aspects of natural resource management and reviewing environmental changes. In this research, using remote sensing technique, the monitoring of changes in vegetation cover and its relationship with surface temperature and land use in Khoda Afarin and Kalibar cities were investigated using remote sensing technology during a period of 22 years (2000-2022). To perform statistical and visual analysis on satellite images, Envi 5.6 and Arc GIS 10.8 software were used. NDVI index was used to investigate changes in vegetation area and quality. Also, in order to investigate qualitative changes in vegetation, the numerical values of this index were classified into three classes: dense, semi-dense, weak or no vegetation, and the temperature changes of the earth's surface during the study period using It was calculated from Landsat satellite images and then the land use maps were extracted based on the supervised classification method and through the maximum similarity algorithm. Based on the analysis, it was determined that in the studied period, 58,196 hectares, about 15.6% of dense vegetation density, and 38,415 hectares, about 10.2% of semi-dense vegetation density, have been lost. In fact, 96,611 hectares, about 25.8% of the density of dense and semi-dense vegetation, have been converted to other uses in 22 years. The study of land use in the region showed that the changes in vegetation density are mostly related to the use of agricultural and garden lands and pastures, and during the study period, the most destruction is related to dense vegetation density. Finally, investigating the relationship between vegetation cover and land surface temperature (LST) showed that the vegetation cover index (NDVI) has a negative and inverse correlation with the land surface temperature and in most areas that have denser vegetation cover; shows a lower temperature. The results of the research show that the most important factor in the changes in vegetation density in the region is human activities such as agriculture, construction and road construction, which have caused many changes in the land surface, the analysis of the area of these land uses shows He said that the level of agricultural lands and pastures has increased significantly, which is mainly the result of the conversion of dense vegetation, especially forests, to agriculture. The results of this research can be used by the organizations of agricultural jihad, natural resources and the Ministry of Interior.

The purpose of this article is to study and analyze the land use dynamics and its impact on the heat islands of the city. This research was conducted for the city of Mashhad and a 10 km wide strip around it with the help of Landsat satellite images in the period 1988 to 2018. The process used includes supervised classification of images, investigation of land use changes during the mentioned period and investigation of changes in land surface temperature (LST) and vegetation density (NDVI) was in land uses and their relationship with land use. The results showed that by 2018, the area of ​​agricultural-garden use decreased by 9.38%, the area of ​​urban and residential areas increased by 12.19%, urban green space increased by 2.11% and other areas increased by 4.93%. The decrease in the level of agricultural-garden areas has been due to their conversion into urban and residential areas. It was also found that changes in man-made land use have led to changes in land surface temperature (LST). An increase in surface temperature and a decrease in the difference between the average temperature of urban areas and areas around the city was observed, which indicates the expansion of the urban heat island phenomenon in the city of Mashhad. The results of this study showed that the use of multi-temporal satellite data and the combination of common methods for studying thermal islands (study of temporal-spatial distribution changes of urban thermal islands compared to changes in urban development, the relationship of thermal islands with vegetation and land use and coverage Lands) can provide a comprehensive view of how urban thermal islands are formed and expanded.

Land surface temperature is a function of net energy at the surface, which depends on the amount of energy reached to the surface, emissions, humidity, atmospheric airflow, topography and climatic conditions of the region. Calculate high accuracy over a wide range. Today, using satellite - remote sensing, can monitor the land surface temperature of the earth, which is one of the important parameters in determining the energy balance of the earth in biological, climatic, hydrological and biological researches. In this paper, to achieve this goal, the daily data of Terra satellite MODIS sensor used to analyze the long-term mean of the monthly period and land surface temperature trend in South Khorasan. The period of these data is daily and includes from 2002 to 2019 equal to 6449 solar days. The spatial separation of the pixel is 1 * 1 km in the sinusoidal networking system, for which 174015 spatial pixel have been extracted in the South Khorasan. Spatial zonation of land surface temperature showed that the surface temperature in this area tends to cluster and implant. During the year, gravity and increasing temperature in the southern, southwestern and western parts of the province, has a high adaptation to low-lying areas in the neighborhood of Dasht-e Kavir and Dasht-e Lut. In addition, the analysis of the surface temperature trend in this province shows that, 1.5% of the province is located in the territory of increasing temperature trend and in the northern and northwestern parts of the province in the strip with Semnan, Isfahan and in the neighborhood of the Dasht-e Kavir and Dasht-e Lut. Less than one percent of the area of ​​the province has a decreasing trend in temperature that observed in most parts of the province, especially in high and mountainous areas. It seems that summer and winter are getting warmer in this province, which should not be overlooked the dynamic role of topography of the region, proximity to large deserts and deserts of Iran, reduced vegetation in the province and maximum absorption of solar radiation temperature in surface temperature changes.

Land use change is one of the factors affecting changes in the environmental parameters, such as land surface temperature. This increase in surface temperature severely affects human life, its health, and the ecosystem around it. In this regard, the present study was conducted to investigate the trend of landuse changes in the urban area of Kerman City and the resulting effects on surface temperature using Landsat OLI and TM satellite data from a period of 1990 to 2020. To achieve this goal, landuse changes in the six major classes of Residential and Man-made areas, Vegetation, Barrenlands with low vegetation, and Saline-lands without vegetation were studied. The results showed that in the study period, Residential and Man-made areas increased by 14.20%, and Vegetation landuses, Barrenlands with low vegetation, and Saline-lands without vegetation also decreased by 3.76, 8.23 and 2.22 percent, respectively.  The landuse changes were detected with a 0.87 kappa coefficient and overall accuracy above 0.90, which indicates sufficient accuracy in classification.The results showed that during the study period, the average value of the LST index increased from 42.26 ° C in 1990 to 47.4 ° C in 2020. The area of the classes above 33 ° C LST has also increased from 6.33% in 1990 to around 31.46% in 2020. The values of the NDVI index were decreasing until 2010, but by 2020, the value of this index has increased again. Node-wise, the study also showed that in 1990, the highest value of land surface was related to Saline-lands without vegetation with an average temperature of 47.30 ° C while in 2000, 2010, and 2020, the highest average temperatures with values of 46.51, 47.30, and 50.64 ° C were respectively related to Urban and Man-made areas. Accordingly, the results obtained in this study can significantly help urban administrators and policymakers with sustainable development and minimize the effects of Kerman's urban heat island.

Human activities such as land-use changes have a significant effect on the Earth’s surface temperature and the creation of heat islands. This study aimed to investigate the impact of land-use changes on the temporal-spatial pattern of the surface temperatures and heat islands in Shooshtar township between 2002 to 2020. First, the Landsat 2002, 2013, and 2020 images were classified using object-oriented processing methods, and then the Earth surface temperature was extracted by the split-window algorithm. Having measured the temporal-spatial changes in the surface temperature and the heat islands, the indices NDVI, UHII, and UHIII were implemented. The results showed an increase in Built-up areas as well as Barrenlands by 21895.40 and 26761.04 hectares, individually. By contrast, the Vegetation cover and Waterbodies decreased down to 43790.79 and 4865.64 hectares, respectively. According to the results, the maximum temperatures index revealed an uptrend in the temperature of all the landuses; there has been a constant increase with an amount of 7.40, 7.42, 6.82, and 6.87 degrees Celsius in the temperatures of the landuses the Vegetation cover, Barrenlands, Built-ups, and Waterbodies, respectively, during the 2002-2020 study period. The UHII and UHIII indices showed that the low land-cover class had a higher temperature than the classes with medium and large land-covers. Furthermore, the heat islands were distinguishably formed by 2013 and 2020 most in the northern, southeastern, and northeastern areas of Shooshtar township.

Spatial mapping of evapotranspiration (ET) rates can indirectly be very important for rangeland management and rehabilitation. The map of evapotranspiration can be an indicator of plant water requirement. Mapping of ET from remote sensing data is more appropriate than field methods, because the spatial and temporal coverage of this method is very extend and time and cost are optimized. Among the evapotranspiration mapping methods using remote sensing data, the FAO-56 model is one of the usual ones. Therefore, this study aimed to spatially estimate the amount of ET in semi-arid region of Isfahan province using the integration of FAO-56 and remote sensing techniques. To calculate ET, Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST) were obtained from geometrically corrected TM 2009 image and the standard crop evapotranspiration (ET0) was calculated using FAO-56 equation and then the crop coefficient (Kc), crop transpiration (Kcb) and soil evaporation (Ke) were extracted from NDVI data. Results showed that agricultural lands with 6/977 mm/day and bare ground with 0.012 mm/day had the highest and lowest ET in the study area. High relationships of ET map with well-known remote sensing maps such a NDVI (>99%) and LST (>92%) indicated that ET mapping in the region has been achieved with a high accuracy, therefore, it is a valuable supplementary technique to field methods in determining plant water requirements for rehabilitation purposes.

Nowadays, different societies are facing increasing population and extensive urbanization. Land use changes is one of the phenomena that is very important in the world and has significantly impact on the environment. The purpose of this research is investigating the effect of land use change on land surface temperature in the central zone of Sanandaj city. Using supervised classification method, maximum likelihood algorithm, the land use map was classified into five categories agriculture, bare, urban, vegetation, and water. The land surface temperature examined using Sebal algorithm in a period of 19 years. The obtained results from land use analysis in the study area revealed that urban, agriculture, vegetation and water areas show an increasing trend but bare lands show a decreasing trend from 2000 to 2019. Minimum land surface temperature arrived to 6.15 ºC and 5.26 ºC in 2000 and 2019, respectively. Also, maximum temperature increased from 49.22 ºC to 51.39 ºC in this 19 years period. The highest surface temperature in both mentioned years were obtained in bare lands. Vegetation and water areas have the lowest surface temperature in this period. Unlike Mediterranean and tropical cities which experience the urban heat island, Sanandaj city, with cold and semi-arid climate, experienced the urban cool island. Urban cool island is due to the surrounding urban areas with bare lands with high surface temperature.

Temperature is one of the most important physical parameters that control the transfer and exchange of energy between different layers of the earth and the atmosphere. LST estimation methods based on satellite images require surface and atmospheric parameters such as surface emissivity, average air temperature, atmospheric transfer coefficient, and water vapor as input. Uncertainty in these parameters causes errors in the retrieval of land surface temperature. This study aimed to compare the accuracy of different methods for estimating atmospheric water vapor in estimating land surface temperature using Landsat 8 images. In this study, atmospheric water vapor was estimated using FLAASH atmospheric correction methods, MODIS sensor images, and SWCVR method. Then, the impact of atmospheric water vapor on land surface temperature accuracy was investigated using the split window and single-channel methods. Validation of Land surface temperature images was performed using cross-validation and ground measurement methods. Therefore, 20 Landsat 8 images related to 2018 and 2019 were used to estimate atmospheric water vapor by the FLAASH atmospheric correction and SWCVR methods, and land surface temperature estimation. MODIS radiance images were used to estimate atmospheric water vapor and the land surface temperature product of this sensor was used for cross-validation. The surface temperature was measured using a thermometer in places with homogeneous cover, for ground-based validation. Results showed that among water vapor estimation methods, the SWCVR method is more suitable for estimating land surface temperature and the split-window method based on the SWCVR method shows the lowest RMSE and MADE at 3.47 and 3.18. Results of RMSE image classification of split-window algorithm based on the SWCVR showed that 1.67% of the area has an error of more than 4 °C and 98% of the study area has less than 4 °C error.

Rapid population growth and the need to provide the necessities of life has caused human beings to change land use widely. In many cases these changes have been accompanied by disruption of balance in nature and providing the possibility of soil erosion. This study was carried out to investigate the effect of land use changes on increasing the intensity of wind erosion. Landsat satellite imagery and implementation of supervised classification by using SVMs were used to prepare land use map. Ground surface temperature was calculated, as one of the effective factors in wind formation, with single channel and split window algorithms in different land uses. In order to make connections between land use changes and wind erosion, effective climatic parameters such as temperature, relative humidity and maximum wind speed were investigated. The highest surface temperature was observed in poor and non-vegetation areas, and the lowest temperature was estimated in highlands and rangelands. Results showed an increase in average temperature as well as maximum and minimum absolute temperature and decrease in relative humidity. Over the past decade, the maximum wind speed in the study area showed a significant increase, and it has increased from eight m/s in 1990 to more than 20 m/s in the last decade. This shows that land use change by removing vegetation cover, as well as the uncontrolled increase of human constructions and creating thermal islands in the last 30 years, has a significant impact on the emergence of climate change and increasing wind speed.

The island's thermal city is one of the most prominent consequences of the expansion of urbanization and metropolitan development. The effects of the formation of thermal islands can play an important role in air quality and, consequently, in general health. The purpose of this study was to investigate the role of surface coatings on climate change in Tehran metropolis. In this study, the required data from the 10 and 11 bands of OLI and TIRS sensors of Satellite Landsat 8 in the summer and winter of 2017 are used. To study the thermal island status, single-band classes were used to study the distribution of ground temperature in the Tehran area and determine the local effects of Thermal Island in the city. Based on research findings, surface temperature and variables vegetation cover, city structural features and wasteland area, normal difference it was obtained to determine the effects of green, bare, blue and residential land on thermal island. The results showed that the effect of Isle of Man in the northern regions of the city is due to the existence of industrial township and mountain topography. There is also a correlation between ground temperature and Tehran's vegetation index, as the surface temperature of the city has increased with decreasing vegetation. Finally, according to research findings, practical proposals have been presented.

The purpose of this study is to track and analyze the environmental effects of droughts by remote sensing indices in Kashan desert and dry zone. Temporal changes of droughts was evaluated using normal Z index in annual and seaonal (spring) scales. Spectral and thermal data from data series of NOAA-AVHRR satellite between 1998 and 2004 were used to determine the drought indices. Vegetative and thermal drought indices were calculated using NDVI, VCI and TCI values derived from NOAA-AVHRR data. Results from applying mentioned indices showed that this area had low vegetation index values as NDVI index was generally less than 0.2. According to NDVI and VCI maps, years of 2000 and 2001 were characterized as drought condition contrary to 2002 and 2004 as rainy years. However, land surface temperature (LST), TCI and VHI indices showed different temperature conditions specifically in the months of April and May. Using validation of results derived from remote sensing indices, test of significance between them and climatic indices was calculated. According to the calculations, climatic condition of the study area was more compliant with the results of vegetation indices. Also thermal condition of the environment was more accurately indicated by thermal indices. According to the results, applying remote sensing data in environmental studies of arid and desert regions like Kashan is recommended.