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

Abstract

Abstract: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 a 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.

Quantification of turbulent heat fluxes for adaptation strategies within urban planning

“…A Q H /Q * quotient of >1 at the URB (December 2010 and January 2011) clearly reflects the influence of the Q F . An assessment of the spatial and temporal variability of the Q F conducted by Ferreira et al (2011), Pigeon et al (2007, Sailor and Lu (2004), Ichinose et al (1999) or Kłysik (1996) has not been performed at present.…”

Simulating the surface energy balance over two contrasting urban environments using the Community Land Model Urban

“…In order to be consistent with the approach followed by Pigeon et al (2008) for Toulouse, the anthropogenic heat released by traffic (QF traffic ) is prescribed using the hourly QF traffic values described in Pigeon et al (2007). The additional heat flux from heating buildings is parameterized directly as a function of the temperature difference between the roof and wall surface temperatures and the interior building temperature.…”

“…Thus, the results from the default URB simulation provides the opportunity to evaluate the CLMU urban heating parameterization based on estimates of QF made for Toulouse by Pigeon et al (2008). Moreover, two additional runs were performed to test the sensitivity of the model with respect to QF: (1) a simulation without QF (hereafter referred to as URB-noQF) and (2) a simulation in which the total anthropogenic heat flux estimated by Pigeon et al (2007) is prescribed (hereafter referred to as URB-QFpre). The effects of these different treatments of anthropogenic heat on outgoing short-and longwave radiation, sensible heat and surface temperatures are discussed in Section 4.3.1.…”

“…On the other hand, the diurnal cycle of anthropogenic heat in winter is overall overestimated (except for the afternoon hours) while summer QF is underestimated throughout the day because of the fact that air temperatures do not fall below the T iB,min threshold. Here, the magnitude of the anthropogenic heat flux is solely caused by the prescribed traffic heat flux based on the inventory from Pigeon et al (2007). A first sensitivity simulation fully prescribes the total observed anthropogenic heat flux as derived in Pigeon et al (2007) (URB-QFpre).…”

“…Here, the magnitude of the anthropogenic heat flux is solely caused by the prescribed traffic heat flux based on the inventory from Pigeon et al (2007). A first sensitivity simulation fully prescribes the total observed anthropogenic heat flux as derived in Pigeon et al (2007) (URB-QFpre). In Oleson et al (2008a), the waste heat generated as a byproduct of heating/cooling buildings was modelled as a sensible heat flux into the urban canopy layer.…”