The drop in aircraft flights because of the coronavirus may affect weather forecasts

The coronavirus pandemic has topped over 380,000 cases globally, with nearly 2 billion people worldwide affected by a lockdown, curfew or other movement restrictions.

Now, it could impact weather forecasts too.

Amid the spread of Covid-19, airlines have had to suspend passenger flights and cut schedules. Experts have found this has led to a severe decrease in aircraft-based observations, which help with weather predictions.

Weather data collected by aircrafts are crucial in forecast models that control daily weather predictions. Aircraft-based observations also help in greatly reducing errors in weather forecasts.

There has been a 42% reduction between March 1 to 23 in the number of aircraft reports received all over the world, the European Centre for Medium-Range Weather Forecasts (ECMWF) said in a news release on Tuesday.

In less than a month, the number of aircraft reports over Europe received and used by the ECMWF went down by 65%.

While international weather services are seeing a dramatic decrease in commercial passenger flights, they still receive valuable aircraft data from overnight cargo and package carriers, according to the National Oceanic and Atmospheric Administration (NOAA).

“Even though a decrease in this critical data will likely negatively impact forecast model skill, it does not necessarily translate into a reduction in forecast accuracy,” Susan Buchanan, a spokesperson for NOAA National Weather Service, told CNN.

This is because aviation industries use other instruments to collect weather data. In the US, the National Weather Service collects “billions of Earth observations” from other sources that feed into their forecast models, Buchanan said.

These include weather balloons, surface weather observation network, radar, satellites and buoys.

Although it will take more time to determine how detrimental the impact of the aircraft reductions will be on weather forecasts, studies have shown that aircraft observations are quite critical.

A study published in 2017 by the American Meteorological Society discovered that utilizing aircraft observations reduced six-hour forecast errors in wind, humidity and temperature by 15% to 30% across the US.

The “substantial reduction” in aircraft observations is expected to continue in upcoming weeks, NOAA’s Christopher Hill said in ECMWF’s news release.

This will likely “generate some measure of impact on the output of our numerical weather prediction systems.”