Spatio-temporal variability of the atmospheric boundary layer depth over the Paris agglomeration

An assessment of the impact of the urban heat island intensity

Sandip Pal, I. Xueref-Remy, L. Ammoura, P. Chazette, F. Gibert, P. Royer, E. Dieudonné, J. C. Dupont, M. Haeffelin, C. Lac, M. Lopez, Y. Morille, F. Ravetta

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Abstract

Within the framework of a French nationally funded project (CO 2-MEGAPARIS) for quantifying the CO 2 emissions of the Paris area, a lidar-based experimental investigation of the variability of the atmospheric boundary layer (ABL) depths was performed over four days in March 2011 under clear sky conditions. The prevailing synoptic settings were mainly characterized by anti-cyclonic situations with low wind. The key aim of this paper is to assess the impact of the urban heat island intensity (UHII) on the spatio-temporal variability of the ABL depths over the Paris megacity. A network of fixed aerosol lidars was deployed inside the city and in the vicinity of sub-urban and rural areas. Additionally, the spatial heterogeneity of the nocturnal boundary layer (NBL) depths over greater Paris area is addressed, thanks in particular, to the deployment of a 355-nm elastic lidar in a mobile van to measure the aerosol distributions. Radiosonde-derived profiles (twice a day) of thermodynamic variables over the sub-urban site helped investigate the temperature inversion above ground and hence to compare the lidar-derived ABL depths. Comparing these two results, an excellent concordance was found with a correlation coefficient of 0.994.Five important factors closely related to the ABL circulation, namely, spatio-temporal variability of the ABL depths, growth rate of the ABL depths, entrainment zone thickness, and near-surface temperature fields including resultant UHII were considered to infer the urban-rural contrasts. The mean NBL depth over the urban area was on average 63 m (45%) higher than its adjacent sub-urban area which was, on occasion, as much as (74 m) 58% higher mainly due to the effect of UHII. Daytime well-mixed convective boundary layer and associated strong turbulent mixing near its top over the urban area showed higher entrainment zone thickness (326 m) than over sub-urban (234 m) and rural (200 m) areas. Temperature growth rates during sunrise increased up to more than 3 °C h -1 over the sub-urban area while over the urban region it was 2.5 °C h -1 or even less. The ABL depths over the urban site decayed more slowly (500 m h -1) than over the sub-urban area (600 m h -1) during the late afternoon transition period suggesting an impact of the UHII on the ABL dynamics over the urban area.

Original languageEnglish (US)
Pages (from-to)261-275
Number of pages15
JournalAtmospheric Environment
Volume63
DOIs
StatePublished - Dec 1 2012

Fingerprint

heat island
agglomeration
boundary layer
suburban area
lidar
nocturnal boundary layer
urban area
urban site
entrainment
aerosol
convective boundary layer
temperature inversion
megacity
urban region
turbulent mixing
clear sky
radiosonde
rural area
surface temperature
thermodynamics

All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Atmospheric Science

Cite this

Pal, Sandip ; Xueref-Remy, I. ; Ammoura, L. ; Chazette, P. ; Gibert, F. ; Royer, P. ; Dieudonné, E. ; Dupont, J. C. ; Haeffelin, M. ; Lac, C. ; Lopez, M. ; Morille, Y. ; Ravetta, F. / Spatio-temporal variability of the atmospheric boundary layer depth over the Paris agglomeration : An assessment of the impact of the urban heat island intensity. In: Atmospheric Environment. 2012 ; Vol. 63. pp. 261-275.
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abstract = "Within the framework of a French nationally funded project (CO 2-MEGAPARIS) for quantifying the CO 2 emissions of the Paris area, a lidar-based experimental investigation of the variability of the atmospheric boundary layer (ABL) depths was performed over four days in March 2011 under clear sky conditions. The prevailing synoptic settings were mainly characterized by anti-cyclonic situations with low wind. The key aim of this paper is to assess the impact of the urban heat island intensity (UHII) on the spatio-temporal variability of the ABL depths over the Paris megacity. A network of fixed aerosol lidars was deployed inside the city and in the vicinity of sub-urban and rural areas. Additionally, the spatial heterogeneity of the nocturnal boundary layer (NBL) depths over greater Paris area is addressed, thanks in particular, to the deployment of a 355-nm elastic lidar in a mobile van to measure the aerosol distributions. Radiosonde-derived profiles (twice a day) of thermodynamic variables over the sub-urban site helped investigate the temperature inversion above ground and hence to compare the lidar-derived ABL depths. Comparing these two results, an excellent concordance was found with a correlation coefficient of 0.994.Five important factors closely related to the ABL circulation, namely, spatio-temporal variability of the ABL depths, growth rate of the ABL depths, entrainment zone thickness, and near-surface temperature fields including resultant UHII were considered to infer the urban-rural contrasts. The mean NBL depth over the urban area was on average 63 m (45{\%}) higher than its adjacent sub-urban area which was, on occasion, as much as (74 m) 58{\%} higher mainly due to the effect of UHII. Daytime well-mixed convective boundary layer and associated strong turbulent mixing near its top over the urban area showed higher entrainment zone thickness (326 m) than over sub-urban (234 m) and rural (200 m) areas. Temperature growth rates during sunrise increased up to more than 3 °C h -1 over the sub-urban area while over the urban region it was 2.5 °C h -1 or even less. The ABL depths over the urban site decayed more slowly (500 m h -1) than over the sub-urban area (600 m h -1) during the late afternoon transition period suggesting an impact of the UHII on the ABL dynamics over the urban area.",
author = "Sandip Pal and I. Xueref-Remy and L. Ammoura and P. Chazette and F. Gibert and P. Royer and E. Dieudonn{\'e} and Dupont, {J. C.} and M. Haeffelin and C. Lac and M. Lopez and Y. Morille and F. Ravetta",
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Pal, S, Xueref-Remy, I, Ammoura, L, Chazette, P, Gibert, F, Royer, P, Dieudonné, E, Dupont, JC, Haeffelin, M, Lac, C, Lopez, M, Morille, Y & Ravetta, F 2012, 'Spatio-temporal variability of the atmospheric boundary layer depth over the Paris agglomeration: An assessment of the impact of the urban heat island intensity', Atmospheric Environment, vol. 63, pp. 261-275. https://doi.org/10.1016/j.atmosenv.2012.09.046

Spatio-temporal variability of the atmospheric boundary layer depth over the Paris agglomeration : An assessment of the impact of the urban heat island intensity. / Pal, Sandip; Xueref-Remy, I.; Ammoura, L.; Chazette, P.; Gibert, F.; Royer, P.; Dieudonné, E.; Dupont, J. C.; Haeffelin, M.; Lac, C.; Lopez, M.; Morille, Y.; Ravetta, F.

In: Atmospheric Environment, Vol. 63, 01.12.2012, p. 261-275.

Research output: Contribution to journalArticle

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T1 - Spatio-temporal variability of the atmospheric boundary layer depth over the Paris agglomeration

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AU - Xueref-Remy, I.

AU - Ammoura, L.

AU - Chazette, P.

AU - Gibert, F.

AU - Royer, P.

AU - Dieudonné, E.

AU - Dupont, J. C.

AU - Haeffelin, M.

AU - Lac, C.

AU - Lopez, M.

AU - Morille, Y.

AU - Ravetta, F.

PY - 2012/12/1

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N2 - Within the framework of a French nationally funded project (CO 2-MEGAPARIS) for quantifying the CO 2 emissions of the Paris area, a lidar-based experimental investigation of the variability of the atmospheric boundary layer (ABL) depths was performed over four days in March 2011 under clear sky conditions. The prevailing synoptic settings were mainly characterized by anti-cyclonic situations with low wind. The key aim of this paper is to assess the impact of the urban heat island intensity (UHII) on the spatio-temporal variability of the ABL depths over the Paris megacity. A network of fixed aerosol lidars was deployed inside the city and in the vicinity of sub-urban and rural areas. Additionally, the spatial heterogeneity of the nocturnal boundary layer (NBL) depths over greater Paris area is addressed, thanks in particular, to the deployment of a 355-nm elastic lidar in a mobile van to measure the aerosol distributions. Radiosonde-derived profiles (twice a day) of thermodynamic variables over the sub-urban site helped investigate the temperature inversion above ground and hence to compare the lidar-derived ABL depths. Comparing these two results, an excellent concordance was found with a correlation coefficient of 0.994.Five important factors closely related to the ABL circulation, namely, spatio-temporal variability of the ABL depths, growth rate of the ABL depths, entrainment zone thickness, and near-surface temperature fields including resultant UHII were considered to infer the urban-rural contrasts. The mean NBL depth over the urban area was on average 63 m (45%) higher than its adjacent sub-urban area which was, on occasion, as much as (74 m) 58% higher mainly due to the effect of UHII. Daytime well-mixed convective boundary layer and associated strong turbulent mixing near its top over the urban area showed higher entrainment zone thickness (326 m) than over sub-urban (234 m) and rural (200 m) areas. Temperature growth rates during sunrise increased up to more than 3 °C h -1 over the sub-urban area while over the urban region it was 2.5 °C h -1 or even less. The ABL depths over the urban site decayed more slowly (500 m h -1) than over the sub-urban area (600 m h -1) during the late afternoon transition period suggesting an impact of the UHII on the ABL dynamics over the urban area.

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