OBSERVER: Monitoring desertification and desert dust plumes with Copernicus data

OBSERVER: Monitoring desertification and desert dust plumes with Copernicus data

OBSERVER: Monitoring desertification and desert dust plumes with Copernicus dataCSO Tanya Walker
Thu, 12/08/2021 – 12:19

Rising air temperature and change in precipitation patterns are some of the more visible effects of climate change. In arid areas of the world, these changes could ultimately lead to an increase in the areas covered by deserts and, in regions where water is scarce, to a general degradation of the land.

The umbrella term for these phenomena is “desertification” and it has various causes. Climate change certainly has a strong influence, but it is also strongly induced by the overexploitation of land and soil. More arid areas result in less fertile land which poses a threat to many communities and ecosystems. Moreover, an increase in the surface covered by deserts causes more sand to be transported by winds, which can have important consequences far from the desert itself.   

The Copernicus services can help monitor desertification and atmospheric transport of sand and dust particles around the world to help policymakers and local authorities take appropriate action.

Monitoring desertification and land degradation

Overexploitation and inappropriate land use, reinforced by the effects of climate change, can lead to land degradation and an increased danger of drought. Land degradation in turn can lead to desertification, especially in areas vulnerable to aridity, threatening biodiversity and the functioning of ecosystems, as well as the food security of local communities. The global component of the Copernicus Land Monitoring Service, implemented by the European Commission’s Joint Research Centre, monitors land cover change, vegetation, the energy budget and the water cycle across the global land surface, providing information that can be effectively used to estimate land degradation and desertification.

One of the indicators of potentially ongoing land degradation and desertification is declining land productivity and water stress. The Copernicus Land Monitoring Service offers products on the state and change of vegetation cover, which is a good indicator of the ecological state of an area, as well as its rate of biomass production.

CLMS Normalized Difference Vegetation Index (NDVI) time series and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) indices were used to estimate the Land Productivity Dynamics included in the World Atlas of Desertification. The Atlas provides a comprehensive, evidence-based assessment of all biophysical and socio-economic aspects of land degradation at a global level and offers a tool for decision-makers to improve local responses to those critical issues. The third version was published in 2018 by the European Commission’s Joint Research Centre.

Global Land Productivity Dynamics. The map shows 5 classes of persistent land productivity trajectories (i.e. ongoing trends in land productivity, from persistent severe decline to persistent increase) from 1999-2013. Source: WAD3-JRC, 2018, Cherlet, M., 2014.

According to the World Atlas of Desertification, over 75% of the Earth’s land area is already degraded to some extent, and over 90% could become degraded by 2050. Persistent decline of land productivity is observed on about 20% of the land surface. The Atlas estimates that land degradation and climate change will lead to a reduction of global crop yields by about 10% by 2050, mostly in areas already affected by food insecurity, such as India or sub-Saharan Africa.

The Copernicus Land Monitoring Service provides essential information for understanding and monitoring desertification, which helps assist local authorities tackle this global issue.

Monitoring desert dust plumes and their predicted impact

Aside from monitoring desertification, it is also important to monitor atmospheric dust and specifically, desert dust plumes which can be transported thousands of kilometres from their source. Indeed, while it is important to note that desert dust plumes play a crucial role in the Earth’s ecosystem, bringing much needed nutrients to phytoplankton in the ocean or fertilising the soil of the Amazon rainforest, they also have negative effects on air quality and human health, reduce visibility and solar energy generation.

The Copernicus Atmosphere Monitoring Service (CAMS) provides forecasts that help scientists study the impacts of dust particles in the atmosphere, help local authorities take adequate preventive measures and help solar energy companies prepare for the impact of the dust clouds ahead of time.

CAMS provides global atmospheric composition and regional air quality forecasts for a wide-range of atmospheric pollutants. The global atmospheric composition forecasts provide twice daily five-day forecast of aerosols, atmospheric pollutants, greenhouse gases, stratospheric ozone and the UV-Index. The European regional air quality forecasts provide daily, four-day forecasts of large and fine particulate matter, different kinds of pollen and other pollutants such as ozone, carbon monoxide (CO), nitrogen dioxide (NO2) and sulphur dioxide (SO2).

When it comes to monitoring desert dust plumes, CAMS provides a handful of relevant products which are openly available from the Atmosphere Data Store (ADS): global forecasts of aerosol optical depth (AOD)[1] and the concentration of large particulate matter (PM10) at the Earth’s surface; regional forecasts of the concentration of dust and PM10 from the surface up to 5 km.

Additionally, the CAMS global forecast system also estimates surface deposition of dust particles, data which are available upon request to the CAMS team at ECMWF.  

CAMS can thus detect any significant dust transport from the Sahara towards Europe several days prior to the event. For example, in early February 2021, Sahara Desert dust caused the white snow-covered slopes of the Pyrenees and the Alps to turn a brownish colour. The CAMS global and regional forecasts had predicted this event several days in advance showing high values of surface PM10 concentrations and aerosol optical depth across southern and central Europe.

Snow in the Pyrenees turns brownish from Saharan dust in early February 2021. Credit: European Union, Copernicus Sentinel-2 imagery – available here.


CAMS global surface PM10 concentration forecast (left) and CAMS dust aerosol optical depth forecast on 5 February 2021. Credit: Copernicus Atmosphere Monitoring Service/ECMWF. Source: Sahara dust episode impacts air quality in European cities

Mark Parrington, CAMS Senior Scientist, noted on the successful prediction of the event: “The main volume of dust centred over southern France on the 6th of February, and it is remarkable how well the CAMS regional 4-day and global 5-day forecasts showed a very consistent shape and location of the dust cloud over the full range of the preceding day’s forecasts”.

Time Series of daily mean analysis of PM10 for the city of Barcelona/Spain, showing a great peak between 05-07 February 2021 that likely originates in the Saharan dust episode. Credit: Copernicus Atmosphere Monitoring Service/ECMWF. Source: Sahara dust episode impacts air quality in European cities

Aside from the unusually coloured snow, CAMS data also showed that this desert plume episode substantially affected air quality. As Mark Parrington put it: “These dust clouds brought with them high values of surface PM10 concentrations and aerosol optical depth. We saw air quality values in the affected regions drop significantly. In fact, the impact of the Saharan dust clouds is clearly visible for affected cities, such as, for example, Barcelona or Marseille on our Website. Our microsite dedicated to monitoring air quality in the context of COVID-19 can be used to see the impact of the event”.

CAMS also successfully predicted a second dust plume moving towards Europe, reaching all the way north to Scandinavia, towards the end of February 2021. Mark Parrington once again highlighted the impact these desert dust plumes can have and the importance of the CAMS forecasts: “high concentrations of dust at the surface can enhance local surface air pollution and can have impacts on, for example, the respiratory health of all people in the affected regions.”

Information provided by the CAMS forecasts can not only help local authorities prepare for the potential health impacts of dust plumes, it can also help solar energy producers better manage their solar farms.

Indeed, desert dust plumes can negatively impact solar energy production, as the dust acts as a restrictive barrier to the sun’s radiation and dust deposits on the solar panels can further reduce energy production. According to a 2017 study by Duke University, accumulated dust particles on solar panels can reduce energy output of solar cells by more than 25% in some parts of the world. As photovoltaic power production increases, there is a growing need for reliable forecasts of incoming solar radiation.

Copernicus – monitoring desertification and desert dust plumes

Ongoing overexploitation and inappropriate land use, combined with the effects of climate change, will likely cause an increase in land degradation and ultimately, in the surface covered by deserts. In turn, this will increase the amount of desert dust being carried around the Earth. This will affect ecosystem and communities living on the edges of existing deserts, as well as citizens and energy producers thousands of kilometres away from the desert.

It is thus important to monitor the evolution of land degradation and desertification around the world. Data from the Copernicus Land Monitoring Service provides much needed insight into the state of land cover change, vegetation, the energy budget and the water cycle around the world, helping scientists and policymakers better understand and monitor land condition and desertification. While the Copernicus Atmosphere Monitoring Service provides essential information for local environmental and health authorities, as well as solar energy producers, to help them prepare for potential health risks and disturbances linked to desert dust plume events.





[1] Aerosol Optical Depth refers to the measure of how much direct sunlight is prevented from reaching the ground by aerosol particles (e.g., dust, smoke, pollution) in the atmosphere absorbing or scattering light.

Thu, 12/08/2021 – 12:00