Fennec - The Saharan Climate System

Lead Research Organisation: Imperial College London
Department Name: Dept of Physics

Abstract

The central Sahara has one of the most extreme climates on Earth. During the northern summer months, a large low pressure system caused by intense sunshine develops over a huge, largely uninhabited expanse of northern Mali, southern Algeria and eastern Mauritania. Temperatures in the high 40s are normal and uplift of dry air through more than 6000m of the atmosphere is routine in what is thought to be the deepest such layer on the planet. This large zone is also where the thickest layer of dust anywhere in the Earth's atmosphere is to be found. Although the central Sahara is extremely remote, it turns out to be vitally important to the world's weather and climate. The large low pressure system drives the West African Monsoon and the dry, dusty air layers are closely related to the tropical cyclones which form over the Atlantic Ocean. Likewise, the dusty air has a strong influence on the way the atmosphere is heated, a process which is poorly understood. It is not surprising that the models we use to predict weather and climate and which are a crucial tool for understanding how the atmosphere works, all have problems in dealing with the central Sahara. Insights into how the climate system works, improving the models and therefore the predictions have all been held back in the case of the Sahara by a lack of measurements of the atmosphere and the processes that make dust and extreme weather. This will always be the case until a team goes to the central Sahara and makes these measurements. A key part of this proposal aims to do just that. We want to set up an array of special instruments, at the surface in two carefully chosen places in the central Sahara, which will monitor the winds, temperatures, dust and so on for an entire year. We will add to this collection for a shorter period of even more intense measurements during the core summer month of June. We plan also to fly instruments attached to an aeroplane overhead the surface array and across the desert so that we can get an idea of the structure of the atmosphere and how it changes through the day. To find out how dust storms work, we will leave 10 weather stations at places where we think dust storms happen frequently. Satellites play an essential role in measuring weather and climate and are especially useful in remote places. The best available information from satellites will help to quantify how weather and climate works in the Sahara. We also expect to improve the way the satellites are able to make their measurements too. Because models are so important to understanding and predicting weather, we will make heavy use of them in this work. We want to know how well the models work over the Sahara and what can be done to improve them. We are especially interested in seeing whether the models work better if we allow them to deal with small parts of the climate system or whether we can still represent extreme places in the Sahara by ignoring these details in the models.

Publications

10 25 50

 
Description Through the collaborative research carried out in this grant we have developed an improved, observationally based, understanding of the processes governing Saharan climate. The measurements collected during the dedicated field campaigns are truly novel and will provide a resource for scientists interested in the region for many years to come. Particular findings from my team include a clear understanding of the factors that can confound dust detection (and hence source identification) from space, a detailed evaluation of the strengths and weaknesses of state-of-the-art satellite aerosol retrieval schemes and the first study of the sub-daily variability in dust radiative effect (the impact of dust on the energy budget) at the surface, top of atmosphere and within the atmosphere over a Saharan site. We also developed a dedicated website to monitor dust activity to support the project which we have subsequently extended to cover other geographical areas for research and for educational activities.
Exploitation Route The results have already been taken forward to inform solar cell/renewable energy network design: this could be extended further. Similarly we have developed climatologies of dust activity that have helped inform a study into the efficacy of solar cooking in Sahelian refugee camps. More directly, the work will be of use to improve both NWP and climate modelling.
Sectors Education,Energy,Environment,Other

 
Description The results been taken forward to inform solar cell/renewable energy network design: this could be extended further. Similarly we have developed climatologies of dust activity that have helped inform a study into the efficacy of solar cooking in Sahelian refugee camps. More directly, the work has been to improve both NWP (weather forecasting) and climate modelling.
First Year Of Impact 2011
Sector Education,Energy,Environment,Other
Impact Types Societal,Policy & public services

 
Description Quantifying the Radiative Impact of Dust aerosol over the Arabian Peninsula and Red Sea and its implications for local, regional and global climate
Amount £400,000 (GBP)
Organisation King Abdullah University of Science and Technology (KAUST) 
Sector Academic/University
Country Saudi Arabia
Start 01/2013 
End 01/2016
 
Description Participation in Imperial Science Festival 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact 3 day event involving interactive displays to demonstrate research activity and outcomes to the general public
Year(s) Of Engagement Activity 2013
 
Description School visits (Hertfordshire) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Schools
Results and Impact Used illustrations from research to encourage female students to select Physics at A-level. School reported enhanced numbers taking the subject in subsequent years.
Year(s) Of Engagement Activity 2013,2014
 
Description Science Late event at the Science Museum London 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Demonstration of the way in which satellites can be used to monitor climate, focusing on specific atmospheric phenomena.
Year(s) Of Engagement Activity 2013