The aim of the project was to identify atmospheric visibility change predictors on a hourly time scale, among multi-sensor observation data sets, including ground-based instruments and satellites. The project involved the collaboration of CNRS and HYGEOS.

Assistance tool for fog formation nowcasting on a site

  • shows the evolution of local observed parameters in real time,
  • shows the evolution of the regional cloud cover observed by satellite,
  • shows results of weather modelling for the site,
  • identifies the fog formation type,
  • computes fog formation probability according to 6 observed predictors [Elias et al., 2017].

One shot of the PreViBOSS animated assistance decision tool.

Animations are proposed for several situations:


Six predictors were selected [Elias et al., 2017], from several parameters which can be observed operationally in an airport:

  • visibility level and change in time;
  • local and regional cloud cover observed by satellite and ceilometer;
  • vertical gradient of temperature.

We also conducted a study on the impact of the hydrated aerosols composing the mist: they can have a significant impact in radiative transfer in the fog as they contribute by ~20% in the visibility drop at the fog formation [Elias et al., 2009]; [Elias et al., 2015].

Particle extinction coefficient computed by Mie for different particle populations.
Extinction in the 2011/11/15 fog is caused not only by fog droplets but also by hydrated aerosols.

Funder: DGA via the RAPID scheme
Duration: 2010 - 2013
Contact at Hygeos: Thierry Elias