Anthropogenic heat release in an old European agglomeration (Toulouse, France)

The anthropogenic heat release, Q(F), has been estimated for the old European agglomeration of Toulouse (France) from February 2004 to March 2005 in the frame of the CAPITOUL experiment. Surface energy balance (SEB) measurements have been conducted at a downtown site, over a dense urban area. A method is proposed to estimate Q(F) at the local scale around this site from observations, as the daily residual term of the SEB equation. The values obtained from this method are in agreement with what can be expected: Q(F) estimates are around 70 W m(-2) during winter and 15 W m(-2) during summer. On,I larger scale (that of the agglomeration), an energy consumption inventory was conducted for the period of the field campaign with a 1-day temporal resolution and a 100-m spatial resolution. The estimates of Q(F) obtained with this second method were analysed at the local scale around the measurements site, and compared with estimates computed from the energy budget observations. For the winter period, both estimates are in good agreement. For the summer period, the method based on SEB measurements seems to underestimate Q(F) which is estimated around 30 W m(-2) from the inventory. The simultaneous estimate Of Q(F), with these two independent methods is a strength of this study. At the scale of the agglomeration, the basal state of energy consumption (observed during the summer period) varies between 25 W m(-2) for the densest areas to less than 5 W m(-2) for the residential suburban areas. In the regions crossed by the major roads, the traffic is the major source during summer. Then during the winter period, Q(F) can reach 100 W m(-2) in the densest areas of Toulouse whereas it ranges between 5 and 25 W m(-2) in the suburban areas. Copyright (c) 2007 Royal Meteorological Society.