LAND SURFACE TEMPERATURES ESTIMATED ON GROUNDOBSERVED DATA AND SATELLITE IMAGES, DURING THE VEGETATION PERIOD IN THE OLTENIA PLAIN
ONŢEL IRINA, IONAC NICOLETA
Abstract. - Land surface temperatures estimated on ground-observed data and satellite images, during the vegetation period in the Oltenia Plain. The purpose of this study is to analyze the land surface temperatures by using climatological and remote sensing data during the vegetation period in the Oltenia Plain. The data used in this study refer both to climatological data (namely monthly and seasonal air and soil temperatures), and to remote sensing data delivered by MODIS Land Surface Temperature (LST), with a spatial resolution of 1 km. The analyzed period spans from 2000 to 2013 and the vegetation period considered is April-September. As main results, there were observed four years with high temperatures, namely 2000 (20.4oC-air T, 24.6oC soil T, and 26oC LST), 2003 (20.2oC air T, 23.9oC soil T and 24.5oC LST), 2007 (20.5oC air T, 24.3oC soil T and 25oC LST) and 2012 (21.3oC air T, 25.7oC soil T and 26.5oC LST). The correlations between air temperature, soil temperature and LST were statisticaly significant. The diference between air temperature and soil temperature values ranked within 3-4oC, while the difference between soil temperature and land surface temperature obtained from MODIS images was about 0.8oC. Spatially, the highest temperatures were recorded on the Leu-Rotunda Field, the Caracal Plain and the Nedeia Field, and pretty high variations of observed temperatures seemed to depend on vegetation cover. The MODIS images represent one of the most important types of satellite data available for free, which can be successfully used in determining the climatic parameters and can help to predict the changes in plant activity, due to weather phenomena.
Keywords: air and land temperatures, satellite images, the Oltenia Plain