The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment

M. Lothon, F. Lohou, P. Durand, F. Couvreux, O.K. Hartogensis, D. Legain, E. Pardyjak, D. Pino, J. Vilà-Guerau de Arellano, A. van de Boer, A.F. Moene, G.J. Steeneveld

Research output: Chapter in Book/Report/Conference proceedingConference paperAcademic

Abstract

BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) aims at better understanding the thermodynamical processes that occur during the late afternoon in the lower troposphere. In direct contact with the Earth surface, the atmospheric boundary layer is governed by buoyant and mechanical turbulence, with a strong diurnal cycle. The late afternoon transition, from the daytime dry convection to the night-time stable boundary layer, still raises a lot of issues and is poorly represented in the meteorological models. Yet, it plays an important role in the transport and diffusion of trace gases, like water vapour, carbon dioxide, pollutants, dusts... How does the afternoon decay in the lower troposphere happen, when the surface sensible heat flux start to sharply decrease ? How do the scales of the motions and transfers change ? What is the impact on the chemical closure and transport of trace gases and aerosols ? How to properly represent those processes in the meteorological models ? An international group is working on those issues by use of observations and numerical simulations, in order to improve our understanding and representation of the turbulent processes of the boundary-layer late afternoon transition. The roles of surface heterogeneity, entrainment at the boundary layer top, large scale subsidence, radiative effects, advection and gravity waves are studied. Due to the large lack of observations during this phase, a field campaign was organized in the vicinity of a 60-m instrumented tower of Laboratoire d'Aérologie, near the Pyrenees ridge in Southwest France, from 14 June to 8 July 2011. This experiment puts together complementary observation resources, in order to obtain an exhaustive description of the boundary-layer dynamical processes, its vertical structure, and the spatial variability related to surface heterogeneity. Continuous measurements (UHF radar and sodar wind profilers, lidars, ground stations), and intensive observations with aircraft, unmanned aerial vehicles, tethered balloons and radiosoundings were used. Particular emphasis was placed to bridge the different spatial scales with an integrated analysis of the observations and a complete numerical model hierarchy. This presentation will give an overview of the field experiment, with an emphasis on specific and innovative instrumental aspects, and with some preliminary results, introducing various contributions of BLLAST participants that will be shown along the 20th BLT conference.
Original languageEnglish
Title of host publication20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA)
Place of PublicationBoston
PublisherAmerican Meteorological Society
Pages14B.1
Publication statusPublished - 2012
Event20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction - Boston, United States
Duration: 9 Jul 201213 Jul 2012

Conference

Conference20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction
CountryUnited States
CityBoston
Period9/07/1213/07/12

Fingerprint

boundary layer
turbulence
trace gas
troposphere
sodar
profiler
sensible heat flux
field experiment
gravity wave
entrainment
water vapor
aircraft
advection
subsidence
carbon dioxide
convection
radar
aerosol
dust
pollutant

Cite this

Lothon, M., Lohou, F., Durand, P., Couvreux, F., Hartogensis, O. K., Legain, D., ... Steeneveld, G. J. (2012). The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment. In 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA) (pp. 14B.1). Boston: American Meteorological Society.
Lothon, M. ; Lohou, F. ; Durand, P. ; Couvreux, F. ; Hartogensis, O.K. ; Legain, D. ; Pardyjak, E. ; Pino, D. ; Vilà-Guerau de Arellano, J. ; van de Boer, A. ; Moene, A.F. ; Steeneveld, G.J. / The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment. 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA). Boston : American Meteorological Society, 2012. pp. 14B.1
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title = "The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment",
abstract = "BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) aims at better understanding the thermodynamical processes that occur during the late afternoon in the lower troposphere. In direct contact with the Earth surface, the atmospheric boundary layer is governed by buoyant and mechanical turbulence, with a strong diurnal cycle. The late afternoon transition, from the daytime dry convection to the night-time stable boundary layer, still raises a lot of issues and is poorly represented in the meteorological models. Yet, it plays an important role in the transport and diffusion of trace gases, like water vapour, carbon dioxide, pollutants, dusts... How does the afternoon decay in the lower troposphere happen, when the surface sensible heat flux start to sharply decrease ? How do the scales of the motions and transfers change ? What is the impact on the chemical closure and transport of trace gases and aerosols ? How to properly represent those processes in the meteorological models ? An international group is working on those issues by use of observations and numerical simulations, in order to improve our understanding and representation of the turbulent processes of the boundary-layer late afternoon transition. The roles of surface heterogeneity, entrainment at the boundary layer top, large scale subsidence, radiative effects, advection and gravity waves are studied. Due to the large lack of observations during this phase, a field campaign was organized in the vicinity of a 60-m instrumented tower of Laboratoire d'A{\'e}rologie, near the Pyrenees ridge in Southwest France, from 14 June to 8 July 2011. This experiment puts together complementary observation resources, in order to obtain an exhaustive description of the boundary-layer dynamical processes, its vertical structure, and the spatial variability related to surface heterogeneity. Continuous measurements (UHF radar and sodar wind profilers, lidars, ground stations), and intensive observations with aircraft, unmanned aerial vehicles, tethered balloons and radiosoundings were used. Particular emphasis was placed to bridge the different spatial scales with an integrated analysis of the observations and a complete numerical model hierarchy. This presentation will give an overview of the field experiment, with an emphasis on specific and innovative instrumental aspects, and with some preliminary results, introducing various contributions of BLLAST participants that will be shown along the 20th BLT conference.",
author = "M. Lothon and F. Lohou and P. Durand and F. Couvreux and O.K. Hartogensis and D. Legain and E. Pardyjak and D. Pino and {Vil{\`a}-Guerau de Arellano}, J. and {van de Boer}, A. and A.F. Moene and G.J. Steeneveld",
note = "recorded presentation: https://ams.confex.com/ams/20BLT18AirSea/flvgateway.cgi/id/21917?recordingid=21917",
year = "2012",
language = "English",
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booktitle = "20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA)",
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}

Lothon, M, Lohou, F, Durand, P, Couvreux, F, Hartogensis, OK, Legain, D, Pardyjak, E, Pino, D, Vilà-Guerau de Arellano, J, van de Boer, A, Moene, AF & Steeneveld, GJ 2012, The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment. in 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA). American Meteorological Society, Boston, pp. 14B.1, 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, Boston, United States, 9/07/12.

The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment. / Lothon, M.; Lohou, F.; Durand, P.; Couvreux, F.; Hartogensis, O.K.; Legain, D.; Pardyjak, E.; Pino, D.; Vilà-Guerau de Arellano, J.; van de Boer, A.; Moene, A.F.; Steeneveld, G.J.

20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA). Boston : American Meteorological Society, 2012. p. 14B.1.

Research output: Chapter in Book/Report/Conference proceedingConference paperAcademic

TY - GEN

T1 - The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment

AU - Lothon, M.

AU - Lohou, F.

AU - Durand, P.

AU - Couvreux, F.

AU - Hartogensis, O.K.

AU - Legain, D.

AU - Pardyjak, E.

AU - Pino, D.

AU - Vilà-Guerau de Arellano, J.

AU - van de Boer, A.

AU - Moene, A.F.

AU - Steeneveld, G.J.

N1 - recorded presentation: https://ams.confex.com/ams/20BLT18AirSea/flvgateway.cgi/id/21917?recordingid=21917

PY - 2012

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N2 - BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) aims at better understanding the thermodynamical processes that occur during the late afternoon in the lower troposphere. In direct contact with the Earth surface, the atmospheric boundary layer is governed by buoyant and mechanical turbulence, with a strong diurnal cycle. The late afternoon transition, from the daytime dry convection to the night-time stable boundary layer, still raises a lot of issues and is poorly represented in the meteorological models. Yet, it plays an important role in the transport and diffusion of trace gases, like water vapour, carbon dioxide, pollutants, dusts... How does the afternoon decay in the lower troposphere happen, when the surface sensible heat flux start to sharply decrease ? How do the scales of the motions and transfers change ? What is the impact on the chemical closure and transport of trace gases and aerosols ? How to properly represent those processes in the meteorological models ? An international group is working on those issues by use of observations and numerical simulations, in order to improve our understanding and representation of the turbulent processes of the boundary-layer late afternoon transition. The roles of surface heterogeneity, entrainment at the boundary layer top, large scale subsidence, radiative effects, advection and gravity waves are studied. Due to the large lack of observations during this phase, a field campaign was organized in the vicinity of a 60-m instrumented tower of Laboratoire d'Aérologie, near the Pyrenees ridge in Southwest France, from 14 June to 8 July 2011. This experiment puts together complementary observation resources, in order to obtain an exhaustive description of the boundary-layer dynamical processes, its vertical structure, and the spatial variability related to surface heterogeneity. Continuous measurements (UHF radar and sodar wind profilers, lidars, ground stations), and intensive observations with aircraft, unmanned aerial vehicles, tethered balloons and radiosoundings were used. Particular emphasis was placed to bridge the different spatial scales with an integrated analysis of the observations and a complete numerical model hierarchy. This presentation will give an overview of the field experiment, with an emphasis on specific and innovative instrumental aspects, and with some preliminary results, introducing various contributions of BLLAST participants that will be shown along the 20th BLT conference.

AB - BLLAST (Boundary Layer Late Afternoon and Sunset Turbulence) aims at better understanding the thermodynamical processes that occur during the late afternoon in the lower troposphere. In direct contact with the Earth surface, the atmospheric boundary layer is governed by buoyant and mechanical turbulence, with a strong diurnal cycle. The late afternoon transition, from the daytime dry convection to the night-time stable boundary layer, still raises a lot of issues and is poorly represented in the meteorological models. Yet, it plays an important role in the transport and diffusion of trace gases, like water vapour, carbon dioxide, pollutants, dusts... How does the afternoon decay in the lower troposphere happen, when the surface sensible heat flux start to sharply decrease ? How do the scales of the motions and transfers change ? What is the impact on the chemical closure and transport of trace gases and aerosols ? How to properly represent those processes in the meteorological models ? An international group is working on those issues by use of observations and numerical simulations, in order to improve our understanding and representation of the turbulent processes of the boundary-layer late afternoon transition. The roles of surface heterogeneity, entrainment at the boundary layer top, large scale subsidence, radiative effects, advection and gravity waves are studied. Due to the large lack of observations during this phase, a field campaign was organized in the vicinity of a 60-m instrumented tower of Laboratoire d'Aérologie, near the Pyrenees ridge in Southwest France, from 14 June to 8 July 2011. This experiment puts together complementary observation resources, in order to obtain an exhaustive description of the boundary-layer dynamical processes, its vertical structure, and the spatial variability related to surface heterogeneity. Continuous measurements (UHF radar and sodar wind profilers, lidars, ground stations), and intensive observations with aircraft, unmanned aerial vehicles, tethered balloons and radiosoundings were used. Particular emphasis was placed to bridge the different spatial scales with an integrated analysis of the observations and a complete numerical model hierarchy. This presentation will give an overview of the field experiment, with an emphasis on specific and innovative instrumental aspects, and with some preliminary results, introducing various contributions of BLLAST participants that will be shown along the 20th BLT conference.

M3 - Conference paper

SP - 14B.1

BT - 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA)

PB - American Meteorological Society

CY - Boston

ER -

Lothon M, Lohou F, Durand P, Couvreux F, Hartogensis OK, Legain D et al. The Boundary Layer Late Afternoon and Sunset Turbulence 2011 field experiment. In 20th Symposium on Boundary Layers and Turbulence/18th Conference on Air-Sea Interaction, American Meteorological Society (9-13 July 2012, Boston, MA). Boston: American Meteorological Society. 2012. p. 14B.1