Blizzard in a forest. Credit: Alex Stemmers

January 2017: freezing temperatures and snow in Central and Southern Europe

19 January 2017 12:00 UTC

Region

Europe, Germany, Atlantic Ocean, Portugal, Spain, Madeira, Iceland, Ireland

Satellites

Meteosat-10, CALIPSO

Instruments

SEVIRI, CALIOP

Channels/Products

Natural Colour RGB, Airmass RGB, Day Microphysics RGB

Freezing temperatures and snow hit Central and Southern Europe in January 2017.

Last Updated

11 November 2022

Published on

19 January 2017

By Jochen Kerkmann (EUMETSAT) and Mike Fromm (US Naval Research Laboratory)

High pressure situation leads to high pollution (fine dust) in Central Europe. Easterly winds push highly polluted air out on the eastern Atlantic, as seen in Meteosat-10 RGB imagery. Due to a large-scale pressure pattern (a high over Western and Central Europe and a low over Mediterranean) Europe was in an easterly flow with quite cold, dry air in early-mid January, as can be seen on the Natural Colour RGB which has the ECMWF 850hPa map overlaid (Figure 1).

Meteosat-10 Natural Colour RGB with ECMWF 850 hPa map overlaid, 19 Jan 12:00 UTC. Credit: EUMeTrain ePort Pro — Figure 1: Meteosat-10 Natural Colour RGB with ECMWF 850hPa map overlaid, 19 January 12:00 UTC. Credit: EUMeTrain ePort Pro

Large areas in Europe were snow covered; the cold air invaded Spain and Portugal, and flowed further west out on the Atlantic where it met warmer, maritime air.

Because of the four-pressure configuration (two highs and two lows) the boundary between the European airmass (cold, polluted) and the Atlantic maritime airmass (warm, moist, clean) was very clear as it stretched along the deformation zone that ran from south of Iceland down to Madeira, as shown in the Airmass RGB (Figure 2).

In the Day Microphysics RGB product (Figure 3), observe the colour difference of the stratocumulus clouds across the deformation zone over the Atlantic, west of Europe — from nice yellow, indicating small droplets and polluted air, to magenta showing large droplets and clean air.

Met-10, 19 January, 12:00 UTC — Figure 2: Meteosat-10 Airmass RGB, 19 January, 12:00 UTC. Credit: EUMeTrain ePort Pro

Polluted air

Figure 4: Track of the CALIPSO daytime pass, 19 January

Due to the persistent high pressure weather, the fine dust values in Germany rose above the permitted limits for a number of days. In Stuttgart and Nuremberg the values even rose to unprecedented heights. On 16 January at the Neckartor in Stuttgart, 188 micrograms fine dust per cubic meter of air was recorded — setting new record. At the highly frequented Von-der-Tann-Straße in Nuremberg, the peak value was 232 micrograms — four times higher than the European-wide limit of 50 micrograms.

These high fine dust values were caused by the lack of winds and the high pressure. The cooling of air layers near the grounded results in an inversion. The warmer air at the top acts as a cover, so that the pollutants near the ground can not spread over the entire atmosphere. Since this 'barrier' was only 150m above the Stuttgart Talkessel (a 2–3km wide hollow in the Keuperbergland) the low mist was full of toxic pollutants.

Mike Fromm, of the US Naval Research Laboratory (NRL), investigated the levels of pollution within the airmass. Using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) data from NASA's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite.

On the daytime pass from 19 January (see zip file) stratocumulus clouds can be seen north of Spain, then some adjacent boundary layer liquid particles to the north, then a little 'clear' air, then more aerosol and stratocumulus clouds north of Ireland.