Wind monitoring satellites need to take more vertical measurements

(ORDO NEWS) — Future wind monitoring satellites should increase vertical resolution to improve measurements in the tropics, writes a group of scientists from the Leibniz Institute for Tropospheric Research, ESA, the European Center for Medium Range Weather Forecasts (ECWMF), the University of Hamburg and Loon.

The quality of weather forecasts depends to a large extent on the available data, so in recent decades a global observing system has been created, which also includes wind profiles from weather balloons and data received from aircraft.

However, most of the information comes from the densely populated Northern Hemisphere. In the Southern Hemisphere, over the oceans and in the tropics, the network of direct measurements is still relatively sparse.

The launch on 22 August 2018 of ESA’s Aeolus satellite was an important step towards global wind measurements.

This new satellite is equipped with a powerful ALADIN laser. ALADIN is the first Doppler wind lidar in space that allows you to get horizontal wind speed profiles from the Earth‘s surface or from the top of dense clouds.

It takes 90 minutes for Aeolus to circumnavigate the world once. During the week, the satellite collects wind data from around the globe. Since there have been no comparable satellite missions so far, the data is compared with other wind measurements.

A recently published study used data from 229 Loon stratospheric balloons between July 2019 and December 2020 from tropical regions of Latin America, the Atlantic Ocean, Africa and the Indian Ocean for comparison.

Loon was a commercial project that provided Internet access to remote regions using helium balloons in the stratosphere.

To maintain the net, the balloons had to take into account the direction of the wind. This has created an extensive data set of wind speeds in these layers of the atmosphere, which partially fills a gap in the wind data at this height in the global observing system.

“Our analysis confirms that the Aeolus satellite provides virtually error-free wind measurements in the upper troposphere and lower stratosphere.

In contrast, the current ECWMF weather model systematically underestimates the wind speed there by about 1 meter per second, which can be demonstrated by the Aeolus and Loon data.

These results are important for a better understanding of the dynamics in the upper troposphere and lower stratosphere and for the further improvement of weather models,” said Dr. Sebastian Blay of TROPOS, who worked on the study at ESA in Frascati, Italy.

The researchers’ recommendation is to take more vertical measurements to be able to provide more information about atmospheric wind. The scientists also hope that future wind monitoring missions will be able to provide more information about aerosols.

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