Fennec is a large multi-national collaboration led by Oxford University that seeks to better understand the Saharan climate. As the dustiest place in the world and the locus of widespread extremes in temperature and pressure, the Sahara plays a key role in regional and global climate. Fennec places a special emphasis on delivering and employing new field observations in the remote desert. Prior to Fennec, an area of the Sahara of roughly 1 million square km had been void of any meteorological observations.
Working together with the meteorological services of Algeria and Mauritania, Fennec deployed over 30 tonnes of meteorological equipment in the remote central Sahara (see map). In addition, 36 research flights were flown by the British BAe146 aircraft and 18 by the French Falcon aircraft, each of up to 5 hours in duration. The results of Fennec research done at Oxford and by partner universities are already changing how we view the climate of the Sahara.
Fennec research themes
Satellite retrieval is an important technique for learning about large and remote regions. Perhaps surprisingly, the location of dust sources in the central Sahara is still equivocal. By developing an automated satellite dust detection scheme and backtracking dust to its point of origin, Dr Ian Ashpole has produced an objective dust source map for the summertime central Sahara.
Fennec datasets provide a unique opportunity to validate satellite retrieval algorithms and to understand their biases and limitations. Such research is being undertaken at Oxford and also at Fennec partner university Imperial College London.
What are the atmospheric mechanisms that cause the central Sahara to be the summertime global dust maximum?
Dr Christopher Allen analyzed the Fennec ground observations and came to a surprising conclusion: the most important dust-producing mechanisms were associated with water, specifically, the West African Monsoon. The monsoon could raise dust as an intrusive surge, promote low-level jets or, most commonly, supply moisture for thunderstorms whose downdrafts caused highly efficient dust storms known as cold pool outflows.
Other Fennec institutions studying the dust mechanisms are Sussex University and the University of Leeds.
The Saharan atmosphere in summer is characterised by deep, hot thermals, creating the deepest boundary layer on the planet. The vertical structure of the Saharan atmosphere and its temporal evolution is a focus of Fennec research. On a larger scale, Fennec is examining the processes that create, maintain or erode the Saharan Heat Low, a thermal low that extends across the desert in the summer months and is responsible for organising atmospheric circulation patterns across West Africa.
Dust, clouds, and dust-cloud interactions modify how the Saharan atmosphere and desert surface are heated and cooled. The Fennec research aircraft provided unrivaled tools with which to measure these effects. A major finding was that dust particles were significantly larger than previously thought or measured – extending up to 300 microns in diameter. Such large particles were found to exert a much more potent heating effect than smaller ones. Fennec radiation research is led by the University of Reading.
Dynamical models can be used to run experiments or to do forecasts. Fennec has made use of both; in addition it has made important contributions to model evaluation thanks to the new observation datasets. An significant finding from Dr Allen’s work is that model wind speeds – at the surface and in the lower troposphere – are typically underestimated compared to observations, with significant knock-on effects for modelled dust emission.
Contacts and Partner Institutions
Prof Richard Washington (PI, Oxford University)
Prof Doug Parker (Leeds University)
Prof Martin Todd (Sussex University)
Prof Ellie Highwood (Reading University)
Dr Helen Brindley (Imperial College)
Dr Cyrille Flamant (LATMOS)
Dr Sebastian Engelstaedter (Oxford University)
Dr Christopher Allen (Oxford University)
Dr Ian Ashpole (Oxford University)
Facility for Airborne Atmospheric Measurements
Laboratoire Atmosphères, Milieux, Observations Spatiales
Office National de la Météorologie, Algérie
Office National de la Météorologie, Mauritanie
Fennec was principally funded by the Natural Environment Research Council. For more details about the project, see the Fennec website.
Publications (with Oxford authors)
- Allen, C.J.T., Washington, R. and Saci, A. (2015) Dust detection from ground-based observations in the summer global dust maximum: Results from Fennec 2011 and 2012 and implications for modeling and field observations. Journal of Geophysical Research: Atmospheres, 120(3): 897-916.
- Allen, C.J.T. and Washington, R. (2014) The low level jet dust emission mechanism in the central Sahara: observations from Bordj-Badji Mokhtar during the June 2011 Fennec Intensive Observation Period. Journal of Geophysical Research.
- Allen, C.J.T., Washington, R. and Engelstaedter, S. (2013) Dust emission and transport mechanisms in the central Sahara: Fennec ground-based observations from Bordj Badji Mokhtar, June 2011. Journal of Geophysical Research: Atmospheres, 118.
- Ashpole, I. and Washington, R. (2013) Intraseasonal variability and atmospheric controls on daily dust occurrence frequency over the central and western Sahara during the boreal summer. Journal of Geophysical Research: Atmospheres.
- Ashpole, I. and Washington, R. (2013) A new high-resolution central and western Saharan summer time dust source map from automated satellite dust plume tracking. Journal of Geophysical Research: Atmospheres, 118(13): 6981-6995.
- Ashpole, I. and Washington, R. (2012) An automated dust detection using SEVIRI: A multiyear climatology of summertime dustiness in the central and western Sahara. Journal of Geophysical Research, 118(D8).
- Engelstaedter, S., Washington, R., Flamant, C., Parker, D.J., Allen, C.J.T. and Todd, M.C. (2015) The Saharan heat low and moisture transport pathways in the central Sahara – multi-aircraft observations and Africa-LAM evaluation. Journal of Geophysical Research: Atmospheres.
- Garcia-Carreras L; Marsham JH; Parker DJ; Bain CL; Milton S; Saci A; Salah-Ferroudj M; Ouchene B; Washington R (2013) The impact of convective cold pool outflows on model biases in the Sahara, Geophysical Research Letters, 40, pp.1647-1652. doi: 10.1002/grl.50239.
- Hobby, M., Gascoyne, M., Marsham, J.H., Bart, M., Allen, C.J.T., Engelstaedter, S., Dieh, M.F., Seddik, F., Gandega, A., Lane, R., McQuaid, J.B., Ouchene, B., Parker, D.J., Rosenberg, P., Salah Ferroudj, M., Saci, A., Todd, M.C., Walker, D. and Washington, R. (2013) The Fennec Automatic Weather Station (AWS) Network: monitoring the Saharan Climate System. Journal of Atmospheric and Oceanic Technology, 30(4): 709-724.
- Marsham, J.H., Hobby, M., Allen, C.J.T., Banks, J.R., Bart, M., Brooks, B.J., Cavazos-Guerra, C., Engelstaedter, S., Gascoyne, M., Lima, A.R., Martins, J.V., McQuaid, J.B., O’Leary, A., Ouchene, B., Ouladichir, A., Parker, D.J., Saci, A., Salah-Ferroudj, M., Todd, M.C., and Washington, R. (2013) Meteorology and dust in the central Sahara: Observations from Fennec supersite-1 during the June 2011 Intensive Observation Period. Journal of Geophysical Research: Atmospheres, 118.
- Rosenberg, P., Parker, D., Ryder, C.L., Marsham, J.H., Garcia-Carreras, L., Dorsey, J.R., Brooks, I.M., Dean, A.R., Crosier, J., McQuaid, J.B., Washington, R., Quantifying Particle Size and Turbulent Scale dependence of Dust Uplift in the Sahara using Aircraft Measurements, 2014, J. Geophys. Res., 119, 12, doi:10.1002/2013JD021255
- Ryder, C.L., McQuaid, J.B., Flamant, C., Washington, R., Brindley, H.E., Highwood, E.J., Marsham, J.H., Parker, D.J., Todd, M.C., Banks, J.R., Brooke, J.K., Engelstaedter, S., Estellés, V., Formenti, P., Garcia-Carreras, L., Kocha, C., Marenco, F., Rosenberg, P., Sodemann, H., Allen, C.J.T., Bourdon, A., Bart, M., Cavazos-Guerra, C., Chevaillier, S., Crosier, J., Darbyshire, E., Dean, A.R., Dorsey, J.R., Kent, J., O’Sullivan, D., Schepanski, K., Szpek, K. and Woolley, A. (2015) Advances in understanding mineral dust and boundary layer processes over the Sahara from Fennec aircraft observations. Atmospheric Chemistry and Physics, 15, 8479-8520.
- Ryder, C.L., Highwood, E., Rosenberg, P., Trembath, J., Brooke, J., Bart, M., Dean, A., Crosier, J., Dorsey, J., Brindley, H., Banks, J., Marsham, J.H., McQuaid, J.B., Sodemann, H., Washington, R., Optical properties of Saharan dust aerosol and contribution from the coarse mode as measured during the Fennec 2011 aircraft campaign, 2013, 13, 303-325, doi:10.5194/acp-13-303-2013, Atmospheric Chemistry and Physics.
- Todd, M.C., Allen, C.J.T., Bart, M., Bechir, M., Bentefouet, J., Brooks, A.B.J., Cavazos-Guerra, C., Clovis, T., Dieh, M.F., Engelstaedter, S., Flamant, C., Garcia-Carreras, L., Gandega, A., Gascoyne, M., Hobby, M., Kocha, C., Lavaysse, C., Marsham, J.H., Martins, J.V., McQuaid, J.B., Ngamini, J.B., Parker, D.J., Podvin, T., Rocha-Lima, A., Traoré, S., Wang, Y. and Washington, R. (2013) Meteorological and dust aerosol conditions over the Western Saharan region observed at Fennec supersite-2 during the Intensive Observation Period in June 2011.Journal of Geophysical Research: Atmospheres.
- Washington, R., Flamant, C., Parker, D.J., Marsham, J., McQuaid, J.B., Brindley, H., Todd, M., Highwood, E.J., Ryder, C.L., Chaboreau, J.-P., Kocha, C., Bechir, M., Saci, A., Fennec – The Saharan Climate System, 2012, No. 60, Vol. 17, No. 3 p31-32, CLIVAR Exchanges.