The presence of urban green areas significantly impacts urban inhabitants' well-being. However, comparative studies across European cities are constraint by urban administrative boundaries, which commonly do not match the continuous built-up urban area. This makes comparative research on environmental indicators very problematic, as administrative boundaries are not usually appropriate to define the urban human environment. Therefore, this study aimis to explore the use of night-time light (NTL) images of the International Space Station (ISS) to delineate the continuous built-up area (CBA) of selected European cities to calculate the urban green area share per alternatively derived city extent. The result of the CBA shows that NTL images provide a robust data source to make the urban extent of European cities comparable. By comparing results of different datasets on green areas, we discuss the limitations of existing indicators and opportunities for new ones. Results show that green areas are rarely in close proximity to human living environment, even though the share of urban green areas within the CBA might be larger, as in comparison to the administrative boundary. We conclude that ISS NTL imagery is very suitable for mapping the CBA when aiming at comparability of environmental indicators across cities.

The aim of this study is to detect ventilation corridors in three epochs (1992, 2002 and 2011) by mapping rough urban areas. The roughness parameters calculations are based on a 3D building database obtained from satellite imagery (SPOT) for thee epochs and are conducted accordingly to morphometric methods. Several ventilation paths are clearly recognisable for all three decades and based on the proximity analysis and roughness parameters (by calculating roughness length (z 0 ) and zero-plane displacement height (z d )), we established their extent and analysed the structural and developmental changes. We conducted that changes occurred more rapidly in the second periodalmost 90% of the study area was gradually built up, what obstructs the air flow. In addition, winds are blocked in the western part of the citywhere the best wind conditions occur. The results urge to re-evaluate the current shape of ventilation corridors and suggest some new areas that should be included in the air ventilation system to improve citizens' comfort and urban climate. ARTICLE HISTORY

Abstract.The aim of this study is to develop a consistent methodology to determine urban areas that are particularly vulnerable to the effects of heavy, rapid rains. They are, as a result of climate change, more and more prevalent in the temperate climate, usually spring -summer from mid-May to late August -and involve the risk of flash floods. In recent years, the increase in incidences of such phenomena is noticeable throughout the whole of Europe. It is assumed that through the analysis of environmental 5 and infrastructural conditions, using the developed methodology, it is possible to determine areas vulnerable to flooding due to torrential rains. This may lead to a better management, quicker response in case of a phenomenon, and even preventative measures to reduce the occurrence of adverse effects of torrential rains (for instance modernisation of the urban drainage system and development of methods to get rid of rapidly collected water). Identifying areas particularly vulnerable to the effects of heavy rains can be achieved by adapting hydrological models, but they require an appropriate adjustment and highly accu-10 rate input data: (based in situ or radar measurements of precipitation, land cover, soil type, humidity, wind speed, vegetation species in a given area, growing season, the roughness and porosity of the cover and soil moisture) but such detailed data are generally hard to obtain or not available for less developed areas. It could also be achieved by performing spatial analysis in GIS environment, which is a more simplified form of modelling, but it gives results more quickly and the methodology can be adapted to the commonly available data. The proposed methodology was tested in Warsaw's central sub-district -Powiśle.

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