Summary:
Land Surface Temperature (LST) is a fundamental variable in the physics of processes of the Earth surface both regional and global level. The meaning of LST is becoming more and more acknowledged and there is intense interest in developing measurement methods from space. The knowledge of LST provides information about temporal and spatial changes of the state of equilibrium of surface and has a fundamental meaning in many applications. It is used vastly in many fields, such us the evapotranspiration, the climate study, the hydrological cycle, the monitoring of vegetation, the urban climate and the environmental studies.
At a local scale, concerning the urban centers, the equilibrium of radiation, the temperature flows and many other climate phenomena have been intensely affected by anthropogenic structures and human activities. One of the results is the enhancement of the phenomenon of Urban Heat Island (UHI), which is depicted through LTS. The monitoring and the study of LTS is valuable for the evaluation and the assessment of the intensity and the extent of this phenomenon.
The aim of this study is to investigate the LST through the MODIS sensor, which is located in the satellite TERRA, and the product MOD11A2. The data have been estimated: LST Day 1km, LST Day 1km Land Cover Mask, LST Night 1km, LST Night 1km Land Cover Mask.
Data from the national laboratory: Oak Ridge National Laboratory Distributed Active Archive Center (ORNLDAAC) https://daac.ornl.gov. have been used for the time span between 2000 and 2017 for the region of Megara in a range of 3x5km, of Thriasio Field in a range of 11x5km, and the area of Athens divided in north, central and south part in a range of 3x5km each and for the Mesogia area in range of 3x5km.
Moreover, the correlation between satellite data with values of air temperature, which have been measured by meteorological stations, located in the areas of Elefsina, Elliniko and the airport Eleftherios Venizelos, using data from the website: https://www.wunderground.com.
It was found that some areas appear minimum values of LST during the day, but the values are higher during the night and respectively, some areas appear maximum values of LST during the day, but the values are lower during the night. That means, there are areas that are not cool as they should be during the night, so they remain warmer. During the day, for the day-night data, the area of Mesogia appear the maximum values of LST, except of July and August which the maximum values present in the area of Thriasio with the deference at 0.2°C and 0.4°C, respectively, but the area, which presents the minimum values of LST, is the southern suburbs of Athens. Based on day-night LCM data, also Mesogia area presents the maximum values of LST, and on the other hand, the area which appear the minimum values LST is, also, the south suburb of Athens. During the night, the area which presents the maximum values of LST, based on the day-night LCM data, is the center of Athens, and the minimum values present at Triasio Field, except of July in which Mesogia appear the minimum LST with deference at 0.1°C. Based on day-night LCM data, the center of Athens appears the maximum LST values and the Mesogia area presents the minimum LST values.
