5. Thermal mapsGeneral information
Infrared thermography provides a picture of the current temperature distribution on the earth's surface. It cannot be compared with any other stationary measuring network as its technology is optimized and provides a large-scale and almost simultaneous temperature measurement of the earth's surface with a high resolution and a large variety of information and data. Temperature measurements conducted by an ordinary measuring vehicle do not always deliver the anticipated information as the measuring points can only be reached with time differences and as the use of a vehicle and therefore the necessity to use roads can lead to various potential errors. Infrared thermography carried out by an aircraft, however, can also lead to ambiguous conclusions. The term "climate measuring flight" is absolutely inadequate here as single thermal infrared pictures do not convey complete information on climate as a complex problem. Above all, the measured surface temperatures are not identical with the local air temperatures, which are taken for meteorological measurements at a consistent altitude of 2 m above ground.
Infrared thermography allows for a snapshot of the temperature distribution on a radiation day and for the identification of differences in the temperature structures of a city in the context of settlement.
The purpose of the analysis is to know more about local air exchange processes through the principles of topographic climatology and to determine those areas within the city which play an important role in the formation of local wind systems.
Such conclusions require, however, a realistic idea of the interaction between the meteorological parameters in the air in the ground layer. And infrared measuring flights can only be analyzed properly with knowledge of the local topographic conditions and in connection with other meteorological information, i.e. as part of a "chain of evidences". Little wind and a marked topography of the area under investigation are important requirements for a promising application of infrared thermography in this context as the formation of local wind systems relevant for the planning can only be expected under these circumstances.
Increasing wind speeds, determined by the geographical position of a place and the large-scale weather situation, blur purely local topographic processes until they are completely superposed by the large-scale weather situation.
Significant temperature differences can occur on a narrow territory as a result of often little ventilation in the area under investigation (see also map-IX) and considerable insolation at the same time.
Local air exchange is induced this way and in the context of various marked topographic structures, and this favours sustainably the efforts for air pollution control and for improving the feeling of climatic comfort.
|© City of Stuttgart, Office for Environmental Protection, Section of Urban Climatology