On 20 March, the shadow of the Moon crossed the Earth causing a solar eclipse.
19 February 2021
20 March 2015
by Jochen Kerkmann and Johannes Müller (EUMETSAT), Sancha Lancaster (Bluemonday) and Ivan Smiljanic (DHMZ)
Parts of Norway, including the Metop Ground Station in Svalbard, saw a total solar eclipse, while other parts of Europe only had a partial eclipse.
The eclipse could be seen on satellite imagery as a large shadow passing over the Northern Hemisphere.
The geostationary location of Meteosat is ideal for following solar eclipses affecting its footprint, and lasting for a few hours, while the shadow of the Moon moves across in an eastward direction (Figure 2).
The solar channels are the most descriptive and dramatic around the umbra darkness. The areas of umbra and penumbra vary with the relative distances Sun-Moon-Earth.
The animated gif (Figure 3) shows the start of the eclipse over Europe seen by Meteosat-10 Natural RGB, 20 March 08:00 to 09:45 UTC.
The eclipse was also be observed by the Hungarian Met Service, using Meteosat-10. This image shows a comparison between AVHRR from 10.25 UTC on 19 March and at 10:04 UTC on 20 March. The shade caused by the eclipse can be clearly seen on the right-hand image.
The shadow can also be clearly seen over Svalbard on the Meteosat-9 Visible 0.6 µm Rapid Scan imagery (Figure 4).
The infrared channels of Meteosat can follow the cooling of a few degrees, due to the total and partial removal of solar illumination for a fraction of an hour in low-latitude eclipses.
The Meteosat-10 infrared animation, 20 March 07:00–10:30 UTC, clearly shows the cooling of the ground during the eclipse (the coldest areas are blue). In many clear-sky areas temperature dropped by as much as 5 °C.
Usually from the early morning the Earth's surface gets warmer and warmer until it reaches maximum temperature around the time Sun reaches its highest position. From the infrared imagery (Figure 5) it is obvious that this heating process was stopped, or even reversed, during the eclipse.
The graphs in figures 5a and 5b clearly show the surface temperature drop during the eclipse. Figure 5a shows the drop over time at one particular pixel in Southern Germany. Figure 5b shows the meteogram from the Darmstadt area in Germany. The thermogram data shows that the temperature stayed more or less constant for about an hour, during a morning period when the temperature had been rising fast.
Importance of satellite imagery
EUMETSAT imagery also proved to be very useful prior to the eclipse, to assess the possible impact of the solar eclipse on the stability of the German electrical power networks.
A solar eclipse (even when only partial) can cause instability in the networks because of the sudden reduction (at the beginning of the eclipse) and later increase (at the end) of electric power from photovaltaik (PV) installations. Weather, in particular cloudiness, plays a crucial role in this.
To mitigate Deutscher Wetterdienst (DWD) developed different scenarios, depending on the predicted cloud cover situation, to help the network companies guarantee stability in this difficult situation. In the two days running up to the eclipse, the forecast models predicted a mixed situation in Germany, with north-west Germany cloudy and central and southern Germany cloud free. The actual situation, shown in the HRV image (Figure 6) shows that the exact border ran along the Taunus mountains, with Frankfurt and Darmstadt cloud free and Cologne and Koblenz cloudy.
Images from the ground
Staff at EUMETSAT, like many offices around Europe, gathered to watch the eclipse, using telescopes, specially adapted cameras and even homemade pinhole cameras (Figure 7).
In the gallery below you can also see images of the eclipse taken by colleagues in the UK and at Svalbard.
The photos in the animation were taken by the equipment shown in the attached photo. The movie consists of 1541 single frames taken at five second intervals. The wobbling is due to manually aligning and cropping the original images, which was needed because of the non correct position of the telescope. Download animation.
YouTube animation of eclipse imagery (Michael Sachweh)
Other solar eclipse cases
Meteosat-8 captures image of partial solar eclipse
On 15 February 2018 a partial solar eclipse was visible from Antarctica, plus many locations within southern South America including Argentina, Chile, Paraguay, and Uruguay.
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Solar eclipse shadow over the Pacific
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Partial solar eclipse over Europe
Meteosat-8 rapid scan service captures images at 5-minute intervals of the partial solar eclipse over Europe (source: MeteoSwiss).
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