Recent Changes of the Urban Local Climate using Satellite Data and In-situ Measurements

The urban heat island is one of the main environmental effects of humans. In this paper the urban climate of a Central/Eastern European capital (Budapest, Hungary) is analyzed using both satellite-based and in-situ measurements. Our study focuses on Ferencvaros, one of the 23 districts of the Hungarian capital. It is located near the river Danube in the southern central part of the city, which is very heterogeneous and consisting of 3- and 4-storey old buildings, block houses with either 4 or 8 levels, brown industrial areas, and large areas occupied by the railways system. Partly due to the functional and structural changes of special subsections of the district substantial local climatic changes occurred in the past few decades. From the local government concentrated efforts were made to complete several block rehabilitation programs already starting from 1980s. Since 1993 in the most densely built inner part of the district entire blocks were renovated and modified in order to create more livable environment for the citizens. Within the framework of these programs inner parts of the blocks were demolished, thus, inside the blocks more common green areas could be created. The climatic effects are evaluated on the basis of the following data. (1) Satellite measurements, namely, surface temperature fields derived from radiation data of infrared channels measured by sensor MODIS (onboard satellites Terra and Aqua), and sensor ASTER (onboard satellite Terra). From the surface temperature data rural mean values around Budapest are used to calculate pixelwise SUHI (surface urban heat island intensity). (2) In-situ temperature and relative humidity measurements within the rehabilitated sections. Our main goal is to analyze whether the generally positive changes of the built environment can also be recognized in the urban heat island effect of this area.