The PARISFOG field campaign at SIRTA site

 

Authors

Martial P. Haeffelin — Institut Pierre Simon Laplace

Alain Protat — Australian Bureau of Meterology
Jean-Charles Dupont — Laboratoire de Météorologie Dynamique (LMD), IPSL
Julien Delanoë — University of Reading
Neda Boyouk — LMD/IPSL/Ecole Polytechnique
Christophe Boitel — LMD/IPSL/Ecole Polytechnique
Florian Lapouge — LMD/IPSL/Ecole Polytechnique
Christophe Pietras — LMD/IPSL/Ecole Polytechnique
Bernard Romand — LMD/IPSL/Ecole Polytechnique
Thierry Elias — HYGEOS Earth Observation
Laurent Gomes — CNRM/Meteo-France
Frédéric Burnet — CNRM/Meteo-France
Daniel Richard — Institut de Physique du Globe de Paris
Luc Musson-Genon — Atmospheric Environment Centre
Eric Dupont — Atmospheric Environment Centre
Yannick Lefranc — Atmospheric Environment Centre
Thomas Lhoir — Atmospheric Environment Centre
Jean Sciare — Climate and Environment Sciences Laboratory
Jose Nicolas — Climate and Environment Sciences Laboratory
Thierry Bourrianne — CNRM/Meteo-France

Category

Field Campaigns

Description

Fogs are weather conditions with significant socio-economic impacts, associated with increased hazards and constraints in road, maritime, and air traffic. While current numerical weather prediction models are able to forecast situations that are favorable to fog events, these forecasts are usually unable to determine the exact location and time of formation or dissipation. One-dimensional assimilation-forecast models have been implemented at a few airports and provide improved local predictions of fog events, but this approach is limited to locations. The occurrence, development, and dissipation of fog result from multiple processes (thermodynamical, radiative, dynamical, and microphysical) that occur simultaneously through a wide range of conditions and that feed back on each other, inducing non-linear behaviors. Hence, to advance our ability to forecast fog processes, we must gain better understanding on how critical physical processes interact with each other, to improve their parametric representations in models. To provide a data set suitable to study these processes simultaneously in continental fog, a suite of active and passive remote sensing instruments and in situ sensors are currently deployed at the SIRTA observatory (http://sirta.ipsl.polytechnique.fr/) near Paris, France, for six months (October 2010–March 2011) to monitor profiles of wind, turbulence, and microphysical and radiative properties, as well as temperature, humidity, aerosol, and fog microphysics and chemistry in the surface layer. This field experiment, called ParisFog (http://sirta.ipsl.polytechnique.fr/parisfog/), is focused on droplet and aerosol microphysics (size distribution between 4 nm and 50µm, liquid water content, black carbon, PM2.5) and on near-surface dynamics (vertical profile between surface and the top of boundary layer height). During this period almost 170 hours of fog, 180 hours of quasi-fog, and 800 hours of near-fog have been documented. Multiple radiative and stratus-lowering fogs occurred, conducting to dense and shallow events of low visibility. The ParisFog field campaign is described and several fog events are analyzed in order to better understand the different processes driving the fog life cycle, especially for the formation and the dissipation period.