ERS SAR imagery for urban climate studies

ERS SAR imagery for urban climate studies

[SDU:STU:ME] Sciences of the Universe/Earth Sciences/Meteorology

[SHS:GEO] Humanities and Social Sciences/Geography

[SPI:SIGNAL] Engineering Sciences/Signal and Image processing

[INFO:INFO_TS] Computer Science/Signal and Image Processing

SAR imagery

urban micro-climate

air quality

roughness

This study investigates the potentialities of ERS SAR imagery for the urban micro-climate and air quality, over the city of Nantes, France. The temporal variability of the SAR signal over the city has been assessed by analyzing five images in descending mode. Beside the speckle effect, the quality of the signal is highly variable from one image to the other. Meteorological effects. make contrasts between objects and their surroundings to be more or less pronounced. Urban features are mostly present in each image, but the structures are not always well perceived within a single image. It is concluded that it is necessary to have several images. Their redundancy allows a better exploitation of the urban features. Further it decreases the level of speckle. Screening of the average SAR image clearly indicates that the perception of the roads is highly dependent on the flight direction of the spacecraft. The main factors for the perception of the morphological features are the height of the buildings, its orientation relative to the spacecraft orbit, its horizontal surface, its materials. Multiresolution analysis, by means of wavelet transform or structure function, provides a good discrimination between unbuilt areas, residential areas, industrial areas, and large groups of buildings. This preliminary study has demonstrated that urban morphological features and their typologies with relation to the air flow drag were well-perceived in SAR imagery once properly processed. Further studies are required to assess definitely the benefits and the limits of such images in urban micro-climate and air quality.

Basly, Ludovic

Cauneau, François

Ranchin, Thierry

Wald, Lucien

Proceedings of 3rd ERS Symposium on Space at the Service of our Environment

3rd ERS Symposium on Space at the Service of our Environment

1997

ENG

conference proceeding

http://hal-ensmp.archives-ouvertes.fr/hal-00461856

http://hal-ensmp.archives-ouvertes.fr/docs/00/46/18/56/PDF/Ers97.pdf

Florence

Italy