CALIFORNIAN SMOKE DRIFTED AS FAR AS EUROPE IN 2020 AND CAUSED HEAVY CLOUDING OF THE SUN

 Published by https://phys.org/

USA – The smoke from the extreme forest fires on the US West Coast in September 2020 traveled over many thousands of kilometers to Central Europe, where it continued to affect the atmosphere for days afterwards. A comparison of ground and satellite measurements now shows: The forest fire aerosol disturbed the free troposphere over Leipzig in Germany as never before. An evaluation by an international research team led by the Leibniz Institute for Tropospheric Research (TROPOS) revealed an extraordinary optical thickness on 11 September 2020, which attenuated sunlight by a third. The study, published in Geophysical Research Letters, is the first publication to show that ESA’s novel Aeolus satellite can not only reliably measure global wind profiles but also aerosols in the atmosphere as it was shown by comparing Aeolus measurements with lidar measurements from the ground. The Center National de Recherches Météorologiques (CNRM) of the University of Toulouse, the German Aerospace Center (DLR) and the European Space Agency (ESA) were involved in the study.

Since August 2018, a new type of research satellite has been orbiting the Earth, named after a Greek wind god—Aeolus. The aim of Aeolus is to actively measure wind from space and thus improve weather forecasting. On board of this satellite of the European Space Agency (ESA) is the Atmospheric Laser Doppler Instrument (ALADIN), a high-performance laser. ALADIN is the first instrument in space that can actively measure vertical profiles of wind speed. It uses the principle of a light radar (short: Lidar from “LIght Detection And Ranging”). A signal is emitted and the reflection provides information about location and distance. The Doppler effect is then used to measure the wind speed at different heights in the atmosphere.

To validate the laser measurements in space, they are compared with laser measurements from the ground. Several research groups from Germany are involved in this effort within the framework of the EVAA initiative (Experimental Validation and Assimilation of Aeolus observations). TROPOS, for example, measures with its lidar devices every Friday evening and Sunday morning when the Aeolus satellite flies over Leipzig. The data from ground and space can then be compared. On 11 September 2020, this resulted in the rare constellation that the extraordinary plume of smoke from the Californian forest fires could be measured over Leipzig simultaneously from ground and from space.

“Using revolutionary laser technology, Aeolus is currently the only satellite in the world that can measure profiles of horizontal wind speed as well as the backscatter and extinction of aerosols and clouds independently. The satellite thus provides valuable information on the radiative properties of these smoke aerosols,” emphasizes Dr. Sebastian Bley of TROPOS, who has been involved in the Aeolus project at the European Space Agency’s (ESA) ESRIN research center for the past three years. “It is expected that this unique configuration will contribute to improved predictions of such global smoke dispersion but also of weather in general.”

Source: https://gfmc.online/2021/06-2021/californian-smoke-drifted-as-far-as-eur...