Mahmoud Ahmadi; AbbasAli Dadashi Roudbari; Hamzeh Ahmadi
Volume 16, Issue 1 , April 2018, , Pages 47-68
Abstract
Introduction: The air temperature parameter is one of the most important measures for identifying the climatic and environmental conditions of each region. Today, by using thermal infrared data, LST maps can be prepared without physical contact with objects or surfaces. Awareness of the spatial and temporal ...
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Introduction: The air temperature parameter is one of the most important measures for identifying the climatic and environmental conditions of each region. Today, by using thermal infrared data, LST maps can be prepared without physical contact with objects or surfaces. Awareness of the spatial and temporal distribution of LST is essential to determine the land energy balance, the evapotranspiration and meteorology studies is essential. LST is a function of pure energy at the land surface which depends on the amount of energy reaching the land surface, surface emissivity, humidity, and air flow. The present study intends to investigate the state of Daytime LST in Iran in different months of the year based on the output of MODIS Terra images.Materials and methods: In this study, the fifth product of MODIS Terra called (Mod11C3 v005) with a spatial resolution of 5×5 kilometer and a Daytime time period, which became monthly data after the necessary processing, was used. In this study, considering the significant precision of day-night-based physics algorithm, Wan et al. (2002) has used this method to study Daytime LST in Iran. Then, they were decoded and an array with the dimensions of 4855×62258 was obtained. Land surface temperature zoning was conducted by using the geostatistical method of kriging with the lowest error rate and the highest precision in mountainous areas.Results and discussion: The statistical characteristics of LST in Iran during different months showed that the highest average of LST in Iran with 46.1 ° C was in July. In the warm period of the year, and in particular, in the hot zones of Iran (the southern coasts) there is less variation in the temperature of the country, which consequently leads to less variation in LST in the country, and less spatial autocorrelation should be observed in the warm half of the year, which indicates a more stable temperature in the warm period of the year. The study of LST during the 15-year period from 2001 to 2015 based on the output of the MODIS sensor for different months of the year showed that the distribution of LST in Iran was severely affected by geographical conditions, especially its latitude and topographic condition.Conclusion: From the west to the east and from the north to the south, there was an increase in LST in all months of the year. The Lut desert is the warmest area in the country with the temperatures rising to 59° C in the warm days. The spatial processing of Daytime LST in Iran showed that LST was strongly affected by latitude and altitude, and the topographic conditions played an important role in the spatiotemporal distribution of LST, which is completely consistent with the studies conducted by who stated that each temperature range has a high degree of consistency with its environmental and geographical properties, in particular its elevation, latitude and slope characteristics.Although the temperature zones provided for the various months of the year have the considerable spatial continuity, the parts of a temperature cluster have appeared in the form of islands in other zones, indicating the effect of complex topographic and local conditions on the occurrence of these temperature islands compared to its surroundings, which causes a spatial variation in temperature and an increase in the desire to LST clustering in Iran, or in other words, to climatic implantation.
