Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 6977-6995, 2016
https://doi.org/10.5194/acp-16-6977-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
07 Jun 2016
Fennec dust forecast intercomparison over the Sahara in June 2011
Jean-Pierre Chaboureau1, Cyrille Flamant2, Thibaut Dauhut1, Cécile Kocha2,a, Jean-Philippe Lafore3, Chistophe Lavaysse2,b, Fabien Marnas2,c, Mohamed Mokhtari3,d, Jacques Pelon2, Irene Reinares Martínez1, Kerstin Schepanski4,e, and Pierre Tulet5 1Laboratoire d'Aérologie, Université de Toulouse, CNRS, UPS, Toulouse, France
2LATMOS/IPSL, UPMC Univ. Paris 06 Sorbonne Universités, UVSQ, CNRS, Paris, France
3CNRM, Météo-France-CNRS, Toulouse, France
4School of Earth and Environment, University of Leeds, Leeds, LS2 9JT, UK
5LACy, Université de la Réunion, Météo-France, UMR8105, CNRS, Saint-Denis de La Réunion, France
anow at: MeteoConsult, Paris, France
bnow at: European Commission, Joint Research Centre, 21027 Ispra Varese, Italy
cnow at: Capgemini Technology Services, Toulouse, France
dnow at: Office National de la Météorologie, Algiers, Algeria
enow at: Leibniz Institute for Tropospheric Research, Permoserstr. 15, 04318 Leipzig, Germany
Abstract. In the framework of the Fennec international programme, a field campaign was conducted in June 2011 over the western Sahara. It led to the first observational data set ever obtained that documents the dynamics, thermodynamics and composition of the Saharan atmospheric boundary layer (SABL) under the influence of the heat low. In support to the aircraft operation, four dust forecasts were run daily at low and high resolutions with convection-parameterizing and convection-permitting models, respectively. The unique airborne and ground-based data sets allowed the first ever intercomparison of dust forecasts over the western Sahara. At monthly scale, large aerosol optical depths (AODs) were forecast over the Sahara, a feature observed by satellite retrievals but with different magnitudes. The AOD intensity was correctly predicted by the high-resolution models, while it was underestimated by the low-resolution models. This was partly because of the generation of strong near-surface wind associated with thunderstorm-related density currents that could only be reproduced by models representing convection explicitly. Such models yield emissions mainly in the afternoon that dominate the total emission over the western fringes of the Adrar des Iforas and the Aïr Mountains in the high-resolution forecasts. Over the western Sahara, where the harmattan contributes up to 80 % of dust emission, all the models were successful in forecasting the deep well-mixed SABL. Some of them, however, missed the large near-surface dust concentration generated by density currents and low-level winds. This feature, observed repeatedly by the airborne lidar, was partly forecast by one high-resolution model only.

Citation: Chaboureau, J.-P., Flamant, C., Dauhut, T., Kocha, C., Lafore, J.-P., Lavaysse, C., Marnas, F., Mokhtari, M., Pelon, J., Reinares Martínez, I., Schepanski, K., and Tulet, P.: Fennec dust forecast intercomparison over the Sahara in June 2011, Atmos. Chem. Phys., 16, 6977-6995, https://doi.org/10.5194/acp-16-6977-2016, 2016.
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Short summary
The Fennec field campaign conducted in June 2011 led to the first observational data set ever obtained that documents the Saharan atmospheric boundary layer under the influence of the heat low. In addition to the aircraft operation, four dust forecasts were run at low and high resolutions with convection-parameterizing and convection-permitting models, respectively. The unique airborne and ground-based data sets allowed the first ever intercomparison of dust forecasts over the western Sahara.
The Fennec field campaign conducted in June 2011 led to the first observational data set ever...
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