SOuth west FOGs 3D experiment for processes study

Coordinator Frédéric BURNET
Type ANR
Partners and Collaborations CNRM, LMD, LATMOS, UK MET OFFICE, the Köln University, MeteoSwiss, ONERA, LA, IRSN, ENM, DSO
Beginning Oct 2018
Duration 4 years


The primary objective of SOFOG3D is to advance our understanding of fog processes at the smallest scale to improve forecasts of fog events by numerical weather prediction (NWP) models. Specifically, SOFOG3D conducts process studies on very well documented situations, using synergy between 3D high-resolution Large Eddy Simulation (LES) and unprecedented detailed observations. A field campaign specifically designed to explore both horizontal and vertical variability of fog layers will be conducted with innovative sensors including in situ and remote sensing networks and Unmanned Aerial Vehicle (UAV) fleet.

 Description of the project

The main objective of SOFOG3D is to advance our understanding of fog processes by conducting process studies on very well documented situations, using synergy between 3D high-resolution LES and unprecedented detailed observations.
To this end, the proposed project is divided into five general tasks (Figure 5) : observations collected during the field campaign feed all other tasks (thin black arrows) : they are processed in task 1 and 2 for in-situ and remote sensing measurements, respectively, used to validate 3D LES case studies in task 3, analysed in synergy with LES results in task 4 to conduct process studies and develop conceptual models, and finally assimilated and used to validate operational forecasts in task 5.
Improvement of our understanding of fog physics will result from reinforced interactions between measurements analysis, 3D LES and process studies (thick purple arrows).
Ultimately derived refinement of processes parametrizations and assimilation strategies will contribute to improve forecasts of fog events by NWP models.

Task1: Field campaign and in situ data analysis (CNRM)
Task2: Fog retrievals based on remote sensing measurements (LATMOS)
Task3 : 3D LES simulation and impact of heterogeneities (CNRM)
Task4 : Advanced process studies based on highly documented cases (LMD,CNRM)
Task5 : Data Assimilation and Forecast (CNRM)


D1.2.1 Conduct the six month field campaign with continuous monitoring and IOP operations
D1.2.2 Database integrated in the AERIS web site at the end of the project
D1.3.1 Analysis of energy budget closure and impact of heterogeneities on the residual.
D1.3.2 Analysis of turbulence anisotropy parameter
D1.3.3 Characterization of CCN activation spectra to prescribe CCN parameterization
D1.3.4 Aerosol absorption properties within fog
D1.3.5 Vertical profile of fog microphysics (droplet size distribution and LWC)
D1.3.6 Analysis of entrainment-mixing processes at fog top

D2.1.1 LWC profiles depending on different constraints from dedicated variational method
D2.1.2 Dynamics of the fog layer from velocity azimuth display technique
D2.2.1 Evaluation of radar LWC retrievial vs in-situ measurements
D2.2.2 Improve radar forward model thanks to calibrated metallic targets
D2.3.1 Improved MWR temperature and humidity profiles retrieved with cloud radar LWC
D2.3.2 Feasibility study of cloud radar LWC assimilation within the MWR 1D-Var framework
D2.4.1 Time series of 2-D maps of cloud classes using a classification adapted for fog and low stratus evolution tracking (e.g. separating core fog, dissipation fog, formation fog pixels)
D2.4.2 Time series of fog evolution indicators, such as distance to fog boundaries, cloud albedo and evolution of brightness temperature of the different cloud classes.

D3.1 : LES simulations of observed fog cases and validation of advances in physical parametrizations
D3.2 : Report analyzing the impact of surface heterogeneities during the fog life cycle
D3.3 : Report analyzing the impact of orography on the formation and evolution of fog

D4.1 Analysis of the transition thin/thick fog and fog-top entrainment
D4.2 Thesis on the stratus-to-fog transition
D4.3.1 LWP budget for each documented fog case
D4.3.2 Sensitivity of fog life cycle to key variables driving major processes

D5.1 Data assimilation trials with different settings and configurations (observations, background-errors, vertical and temporal resolutions)
D5.2 Data assimilation strategy for an optimal use of «fog sensitive» observations to improve NWP fog forecasts
D5.3 Quantitative evaluation of the benefit on the fog forecast using in-situ observations

 Partners and roles

The project involves 3 French partners (CNRM, LMD/IPSL, LATMOS/IPSL) whose expertise encompasses all the required skills to tackle the challenges raised in that project. They have already collaborated in fog related projects (ParisFOG experiments since 2006 funded by LEFE, PreViBOSS 2010-2013 funded by DGA.)
The experiment seeks an international dimension with participation of the Met Office (PI J. Price), the Köln University (PI U. Löhnert), the CNR-IMAA, (PI D. Cimini) and MeteoSwiss (PI A. Haeffele). This international collaboration on the MWR network is driven by the European COST action TOPROF which aimed at an operational use of MWR observations among other instruments.

 Work in progress

 Final meeting - 12 juin 2023
Hybrid meeting : CIC and BlueJeans 9h30-17h30 - 30 personnes

Main objective : review main results obtained so far and discuss plans for future projects.
— 9h00 : Welcome coffee
— 9h30 : Intro – update on the project & Task 1 report – F. Burnet
— 10h25 : In situ microphysics and tethered balloon measurements – T. Costabloz
(Coffee break)
— 11h25 : Radiative closure - Intership – A. Veau
— 11h55 : Observations of fog droplet deposition at Le Couye - J. Price
— 12h15 : Radar measurements – Task 2 report - J. Delanoë
— 12h45 : UKMO UM report - A. Mccabe
(Lunch break)

— 14h00 : AROME forecast report – S. Antoine
— 14h35 : Impact of surface heterogeneities on the fog life cycle - M. Taufour
— 15h00 : Contrasting the evolution of radiation fog over a heterogeneous region - J. Price / J. Thornton
— 15h15 : Task 3 report - C. Lac
— 15h50 : Role of thermodynamics and turbulence processes on the fog life cycle – C. Dione
— 16h30 : Fog formed by stratus lowering – M. Fathalli
— 17h05 : Task 4 report - M. Haeffelin
— 16h30 : Enf of meeting (General discussion canceled)

 Data and Science meeting III - 7 juin 2022
Visio BlueJeans 9h30-17h - 25 connected

Main objective : review on-going work and share the latest results to plan future work.
— 9h30 : Intro – update on the project & AERIS database – F. Burnet
— 9h45 : In situ microphysics and tethered balloon measurements – T. Costabloz
— 10h15 : Aerosols measurements – I. Vonpaseut
— 10h30 : Observations of fog droplet deposition at Le Couye - J. Price
— 10h50 : Observations at two 50m-mast sites over two radiation fog cases in Oct. 2019 - J. Thornton
— 11h10 : Radar measurements – Task2 - J. Delanoë
— 11h40 : Synergy MWR/radar – P. Martinet / PhD A. Bell
— 12h00 : MWR network and assimilation - Task5 - P. Martinet
— 12h10 : MWR assimilation trial - G. Thomas
(Lunch break)
— 14h00 : AROME fog forecasts and influence of microphysical parameterizations – S. Antoine
— 14h50 : UKMO – Comparison between the deterministic model output and observations. J. Thornton
— 15h20 : 3D LES Meso-NH and heterogeneities – Task 3 – M. Tauffour
— 15h50 : Formation of fog due to stratus lowering – Task 4.2 – M. Fathalli
— 15h50 : Fog dissipation phase process studies – Task 4.3 – C. Dione
— 16h30 : General discussion : data analysis, collaborations, papers, next meeting, etc...

 Data and Science meeting II - June 6, 2021
Visio BlueJeans 9h30-17h - 35 connected

Main objective : review on-going work and share the latest results to plan future work.
— 9h30 : Intro – update on the project – F. Burnet
— 9h40 : Update on the AERIS database – W. Maurel
Discussion on data status
— 9h50 : In situ microphysics – T. Costabloz
— 10h20 : Turbulence and flux measurements – W. Maurel
— 10h30 : MWR network and assimilation - Task5 - P. Martinet
— 11h00 : Radar measurements – Data processing - J. Delanoë
— 11h15 : Radar measurements – Retrieving cloud properties - P. Vishwakarma
— 11h30 : Synergy MWR/radar – A. Bell
12h00 : Parafog v2 – J.F. Ribaud
— 12h15 : Update on the MO data analysis and future aims – J. Thornton / J. Price
(Lunch break)
— 14h00 : Evavuation of AROME – S. Antoine
14h30 : MO ensemble modelling – work in progress and future plans - A. McCabe
— 15h00 : Ensemble modelling with PE-AROME – M. Letillois
— 15h30 : 3D LES and heterogeneities – Task 3 – M. Tauffour
16h00 : Advanced process studies – Task 4 – M. Haeffelin
16h30 : General discussion : data analysis, collaborations, papers, next meeting, etc...

 Modeling meeting CNRM - May 17, 2021
Visio BlueJeans 9h-11h - 12 connected
— Prévision du brouillard avec AROME : résultats statistiques – S. Antoine
— Etude de la prévisibilité du brouillard à l’aide de la PEARO - M. Letillois
— Impact des hétérogénéités de surface sur le brouillard - M. Taufour

 Modeling meeting with UKMO - March 30, 2021
Visio BlueJeans 15h-17h - 13 connected
— Statistical study on arome forecast during SOFOG3D – sensitivity tests on
parametrization and model resolution
– S. Antoine
— SOFOG3D – UK Met Office update on UM model comparison with observations – J. Thornton
— SOFOG: Ensemble Fog Forecasting – A. McCabe

 Data and Science meeting part II - November 25, 2020
Visio BlueJeans 14h-16h30 - 25 connected

Main objectives will be to discuss the preliminary results presented at the last meeting and the future plans for data analysis.
It might be interesting for everyone involved in the data analysis to prepare one slide to share their plans with the science questions they want to address and how.
This will hopfully stimulates collaborations and avoids duplication of work.
We’ll also review publication intentions to draw up a first list.
An important point concerns the access and management of the database :
— AERIS database website – W. Maurel

 Data and Science meeting I - November 9, 2020
Visio BlueJeans 9h-13h - 54 people connected

Main objectives of the meeting were to present the available data set, discuss the first results from preliminary analysis and determine the best analysis strategy for the rest of the project.
The program was ambitious for just one half day and the extremely dense presentations took longer than expected.
A second meeting will then be organized very soon to present AERIS data website, discuss plans for data analysis and and review future papers considered by the different groups and collaborations.

— Intro and 2019-2020 campaign overview — F. Burnet
— MWR network – assimilation Task5 - P. Martinet
— temperature profiling with MWR - A. Kremer
— Radar measurements - Task2 - J. Delanoë / S. Jorquera / P. Vishwakarma
— Evaluation of a 95 GHZ Radar Simulator - A. Bell
— UKMO contribution – J. Price
— Turbulence and flux measurements - G. Canut / A. Roy
— Effect of aerosol on fog life cycle - S. Tinorua
— UAV measurements - J. Viviand
— 3D LES and heterogeneities – Task 3 – C. Lac / Q. Rodier
— Advanced process studies – Task 4 – M. Haeffelin / C. Lac
— St to fog transition – Task 4.2 – M. Fathalli
— Evaluation of AROME model – S. Antoine
— AERIS database website – W. Maurel

 Seminar CNRM - Oct. 15, 2019

Frédéric BURNET
Christine LAC

 Kick off meeting - April 16, 2019

Here is an agenda attempt for our meeting next Tuesday. A constrain is to make it in half a day, to start the sites visit in the afternoon.
The meeting will be held at the CIC - Commission 2 room.

9h : welcome coffee
9h30 : project overview, experimental strategy, sites search — F. Burnet (20’)
9h50 : UKMO contribution, LANFEX experience - J. Price (20’)
10h10: MWR network – WP 5 - P. Martinet (20’)
10h30: Task 2 - radar strategy - P. Martinet / J. Delanoë (20’)
10h50: Task 3 & 4 – 3D LES simulation & Advanced process studies - C. Lac & M. Haeffelin (20’)
11h10: Task 4.2 – Stratus to fog transition (PhD) - M. Fathalli (10’)
11h30: round table of PI scientific objectives (1h)
— turbulence and flux measurements - G. Canut
— aerosol measurements and closure - C. Denjean
— aerosol modeling LIMA for AROME - Y. Seity
— turbulence modeling – R. Honert
— radiative closure - Q. Libois
— stable layer dynamics - A. Paci
— machine learning for boundary layer detection - T. Rieutord
— ?????
=> this is a very preliminary list : all people who want to contribute are very welcome. Please let me know by email
12h30: next step (20’)
data policy, AERIS website, CDD/ post doc positions. Campaign organisation.
Next meeting date.

 Publications - Conférences

Costabloz, T., Burnet, F., Lac, C., Martinet, P., Delanoë, J., Jorquera, S., and Fathalli, M.: Vertical Profiles of Liquid Water Content in fog layers during the SOFOG3D experiment, EGUsphere [preprint],, 2024.

Dione, C., Haeffelin, M., Burnet, F., Lac, C., Canut, G., Delanoë, J., Dupont, J.-C., Jorquera, S., Martinet, P., Ribaud, J.-F., and Toledo, F.: Role of thermodynamic and turbulence processes on the fog life cycle during SOFOF3D experiment, EGUsphere [preprint],, 2023.

Thornton J., J. D. Price, F. Burnet, and C. Lac., Contrasting the evolution of radiation fog over a heterogeneous region in south-west France during the SOFOG3D campaign. Quart. J. Roy. Meteor. Soc., 1–19., 2023.

Antoine, S , R. Honnert, Y. Seity, B. Vié, F. Burnet, and P. Martinet. Evaluation of an improved AROME configuration for fog forecasts during the SOFOG3D campaign. Weather and forecasting, 38, 9, 1605-1620,, 2023.

Vishwakarma, P., Delanoë, J., Jorquera, S., Martinet, P., Burnet, F., Bell, A., and Dupont, J.-C.: Climatology of estimated liquid water content and scaling factor for warm clouds using radar–microwave radiometer synergy, Atmos. Meas. Tech., 16, 1211–1237,, 2023.

Martinet, P., Unger, V., Burnet, F., Georgis, J-F., Hervo, M., Huet, T., Löhnert, U., Miller, E., Orlandi, E., Price, J., Schröder, M., Thomas, G.: A dataset of temperature, humidity, and liquid water path retrievals from a network of ground-based microwave radiometers dedicated to fog investigation. Bull. of Atmos. Sci.& Technol., 3, 6 (2022)., 2022

Bell, A., Martinet, P., Caumont, O., Burnet, F., Delanoë, J., Jorquera, S., Seity, Y., and Unger, V.: An Optimal Estimation Algorithm for the Retrieval of Fog and Low Cloud Thermodynamic and Micro-physical Properties, Atmos. Meas. Tech., 15, 5415–5438,, 2022.

Marquet, P., Martinet, P., Mahfouf, J.-F., Barbu, A. L., and Ménétrier, B.: Towards the use of conservative thermodynamic variables in data assimilation: a case study using ground-based microwave radiometer measurements, Atmos. Meas. Tech., 15, 2021–2035,, 2022.

Conférences :

Cimini, D., Gandoin, R., Fiedler, S., Wilson, H., Pospichal, B., Martinet, P., Balotti, A., Gentile, S., and Romano, F.: Assessment of atmospheric stability measurements from microwave radiometer observations for offshore wind energy applications, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12954,, 2022.

Martinet, P., Bell, A., Caumont, O., Vié, B., Burnet, F., and Delanoë, J.: Optimal estimation of thermodynamic and microphysical profiles within fog events from ground-based microwave radiometer and cloud radar synergy., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12410,, 2022

Thomas, G., Martinet, P., Brousseau, P., Chambon, P., and Burnet, F.: Data assimilation experiments of a ground-based microwave radiometer network for fog forecast improvement., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022,
EGU22-7025,, 2022.

McCabe A., J. Thornton, J. Price, P. Field, A. Lock, S. Derbyshire, and A. Hill : The potential benefits and challenges of using ensembles to forecast fog. 14th Symposium on Aerosol-Cloud-Climate Interactions, AMS Metting 2022, Houston, 24-27 January 2022.

Martinet P., A. Bell, A. Kremer, M. Letillois et al: Benefit of microwave radiometer and cloud radar observations for data assimilation and model evaluation studies during the SOFOG3D experiment, 2021 EMS Annual Meeting 2021, online, 6–10 Sep 2021, EMS2021-232,, 2021.

Vishwakarma, P., Delanoë, J., Le Gac, C., Bertrand, F., Dupont, J.-C., Haeffelin, M., Martinet, P., Burnet, F., Lac, C., Bell, A., Vignelles, D., Toledo, F., Jorquera, S., and Vinson, J.-P.: Fog Analysis during SOFOG3D Experiment, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9941,, 2021.

Burnet, F., Lac, C., Martinet, P., Fourrié, N., Haeffelin, M., Delanoë, J., Price, J., Barrau, S., Canut, G., Cayez, G., Dabas, A., Denjean, C., Dupont, J.-C., Honnert, R., Mahfouf, J.-F., Montmerle, T., Roberts, G., Seity, Y., and Vié, B.: The SOuth west FOGs 3D experiment for processes study (SOFOG3D) project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17836,, 2020.

View online : Conférence IFDA2019