On 1 April, the Global Ozone Monitoring Experiment (GOME-2) instruments on Metop-A and B observed elevated levels of NO2 total column concentration over parts of Germany, Belgium, the Netherlands and England.
At the same time elevated aerosol thickness was observed over the North Sea and over the Channel area. Note: GOME-2 can currently only observe aerosol concentration over water surfaces.
RGB Dust animation, 28 March 12:00 UTC–31 March 12:00 UTC (MPG, 3 MB)
by Ruediger Lang (EUMETSAT)
In late March a large amount of Saharan dust was transported to Europe, this was still being carried to South-East England on 1 April.
Also, as shown in this RGB dust video, 1 April 08:00 UTC–2 April 08:00 UTC (Source: Met Office/YouTube), further dust was lifted into the atmosphere on 1 April. The dust can clearly be seen being carried north towards Europe.
The animated gif is derived by the O3MSAF (DLR/EUMETSAT)
The animated gif is derived from Metop, GOME-2, AVHRR and IASI.
Convection RGB, 3 April 12:00 UTC
On the daytime convection RGB (Source: EUMeTrain) the dust-polluted clouds can be seen as the large yellow area.
Dust aerosols have a large impact on cloud microphysics such as cloud phase and cloud particle size.
In general, clouds that have ingested dust glaciate more quickly, forming a large number of very small ice particles. These have a higher reflectance than large ice particles in the 'microphysical' channels (near-IR 1.6 and IR 3.9 micrometer), so they appear as bright yellow in the convection RGB.
Met Office air pollution forecast, 2/3 April
The formation of aerosols, or Particulate Matter (PM), may originate from natural or anthropogenic sources. In industrial areas aerosols may be formed through the emission of gases like NOx, SOx or formaldehyde (HCHO), from combustion processes which form larger particles through chemical reactions in a process called secondary aerosol formation.
Belgium, the Netherlands, the German region of Ruhrgebiet and southern Britain are known to have elevated NO2 concentrations throughout the year, due to industrial emissions and emissions from traffic.
The formation of particulate matter or aerosols from these precursor gases depends largely on the weather conditions, including wind speed, humidity and temperature. A lack of rain over western Europe significantly contributed to the situation.
But also the inflow of natural aerosols, like long-range transport from Saharan dust, may contribute to the overall levels of abundant levels of PM, leading to a mixed-case scenario.
Air pollution: High levels to spread across England (BBC News)
UK smog alert: vulnerable people advised to stay indoors (The Guardian)
Pollution Forecast (Department for Environment Food & Rural Affairs)
Air quality forecast FAQ (Met Office)
WMO Sand and Dust Storm Warning Advisory and Assessment System (SDS-WAS)
Dusty Cirrus over Romania
Cellular convection in cirrus clouds
Forecasting coloured rain in Bulgaria