Coronavirus-linked decline in aviation affecting weather forecasts

Weather data are usually collected by aircraft--most of which the pandemic have grounded.

Weather stations around the world are deploying more weather balloons since the coronavairus pandemic cut flight data. Image: Robin van Lonkhuijsen / EPA

The coronavirus epidemic may make daily weather predictions less accurate, according to meteorologists.

Flight data plays a big role in weather forecasting. When airborne, planes relay real-time information on temperature, air pressure as well as on wind direction and speed. This information is fed into weather forecasting models used by meteorologists.

However flights over the European continent have dropped to one-fifth of pre-pandemic volumes. Today some 10,000 planes fly over Europe each day, mostly carrying cargo.

Meanwhile data collection has decreased as airlines have cut schedules. This is can make medium-range forecasts less accurate, according to Sami Niemelä, director of the meteorological and marine research programme at the Finnish Meteorological Institute (FMI).

Niemelä, however, pointed out that aircraft reports are just one of several meteorological tools available.

More weather balloons

Scientists also use radiosondes to record observations from the upper atmosphere. This is usually done by expanding a weather balloon with hydrogen or helium, allowing it to rise 30 kilometres into the atmosphere. The radiosonde captures information about air pressure, temperature, humidity and wind during both ascent and descent.

Every day the FMI launches four weather balloons--up from twice a day before the pandemic--in Jokioinen near Forssa in southern Finland as well as in Utsjoki in the far north.

Forecasters also have satellite imaging, weather cameras, offshore buoys, surface weather and ship observation data at their disposal.

"Predicting a certain type of weather may in some instances be a bit more difficult now," Niemelä explained.

"Slightly more uncertainty"

Yle meteorologist Joonas Koskela said the decrease in aircraft reports has not been making his job too difficult.

Story continues after photo.

Yle meteorologist Joonas Koskela. Image: Nella Nuora / Yle

"Perhaps there has been slightly more uncertainty in forecasting weather several days at a time,” he said, adding that rain predictions have varied more than usual lately.

"But this can be due to the record-mild winter, making it more difficult for forecasting models to make sense of the current situation."