website free tracking BUBBLE: Project Overview
 
project overview

Experimental and/or modeling studies to investigate the urban boundary layer are often focused on either the exchange processes near the surface or the flow in its upper part - but rarely both aspects are given equal weight. BUBBLE (COST action 715 - Meteorology applied to urban pollution problems) therefore brings together research groups interested in the subject and representing both aspects.

 

 

BUBBLE is made possible by a large number of grants and resources from many institutions: 

  • The core project was funded by the Swiss Ministry of Education and Science (Grant C00.0068).
      

  • SF6-tracer release experiments and the wind tunnel study are provided though grant TH 35/02-1 of the Swiss Federal Institute of Technology (ETH Zürich) 
      

  • The analysis of the dispersion data is supported by NATO Linkage Grant (EST-CLG-979863). 
      

  • The analysis of the satellite data is supported by the Swiss National Science Foundation grant No. 2100-067964. 
      

  • The involvement of the Bulgarian project partners was partly supported through an Institute Partnership financed by the Swiss National Science Foundation (grant 7IP 065650.01) 
      

  • The research of street canyon energetics are founded by GR-022 of the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS) and a Discovery Grant of the Natural Sciences and Engineering Research Council of Canada (NSERC)
      

  • Finally, many parts of the project are supportd by internal funding of the University of Basel (CH), Risĝ National Laboratory (DK), University of Hamburg (D), University of Western Ontario (CA), TU Dresden (D), National University of Singapore, Indiana University (USA) and University of Padova (I).
     

  • The "Lufthygieneamt beider Basel", MeteoSwiss, METEK GmbH, UMEG Karlsruhe provided pollution or meteorological data.

A yearlong operation of surface and surface based remote sensing instrumentation in the city of Basel (Switzerland) was carried out between August 2001 and July 2002. At 'surface'-sites the vertical structure of turbulence characteristics within the urban roughness sublayer was observed in detail. 

At the same time, the flow field in the bulk of the urban boundary layer was monitored using remote sensing techniques (wind profiler, SODAR, RASS and LIDAR). In the Intensive Operation Period (IOP) in June / July 2002 additional instrumentation that is more limited by the available manpower (scintillometric measurements, tethered balloons) was deployed.

During the IOP a series of tracer experiments were carried out. The tracer experiments yield by giving rise to translate the results concerning the flow and turbulence structure of the urban boundary layer into parameterisations for an urban meteorological pre-processor and fill in a gap of missing near-surface tracer release experiments over urban areas.

In combination with the surface data, Satellite Remote Sensing is used to compute spatially resolved radiation and heat fluxes in the city of Basel for selected overpasses during the IOP.

A mesoscale meteorological model is utilised complementary to the observational data. On one hand, the observational data is used to validate generalise and possibly improve some aspects of the urban turbulence and surface exchange parameterisations. On the other hand, the still limited spatial resolution of the observational data can be improved by means of the model simulations.

A wind tunnel model of the central city part "Kleinbasel" at the scale 1:300 will provide an extensive reference data set for urban turbulence and pollutant dispersion particularly suited for the comparison with numerical model predictions. It is also expected to complement and help the interpretation of the full scale measurements which have been made within the model area at the main urban site.

Over all, it can be expected that the project will help to substantially increase our knowledge on the urban wind field, the associated surface energy balance and the resulting (urban) mixing height. This knowledge can directly be translated into parameterisation for urban meteorological pre-processors for dispersion modelling and will also guide the turbulence parameterisations in NWP models when grid resolution will have dropped below urban scale.


> Instrumentation (IOP)
> Instrumentation (Full Year)
> BUBBLE Project Press Release (28.9.2001, in german).