This image of Lake Geneva was captured by the Sentinel-2A satellite on Friday, 24 April, and shows deposits of pollen that match the currents on the lake surface. For remote sensing expert Daniel Odermatt of the Eawag aquatic research institute, the image is not only aesthetically pleasing but also extremely interesting because the currents that are suddenly visible can be compared with models. Indeed, the pattern shows very good agreement with the calculation issued for the same day on www.meteolakes.ch.

The large, central gyre off the shore of Lausanne rotates approximately once every two days. “We have many individual point measurements taken from boats or from the floating platform LéXPLORE,” says Odermatt, “but the patterns in the satellite photos help us gain a better understanding of the lake’s behaviour across its entire surface.”