Behind the Forecast: COVID-19’s unexpected impact on weather forecast accuracy

Science Behind the Forecast: COVID-19's unexpected impact on weather forecasts

LOUISVILLE, Ky. (WAVE) - The coronavirus’s impact on our society has filled the recent news cycle. The lack of air travel because of the coronavirus could lead to a less accurate forecast.

Aircraft consistently buzz around our planet, collecting and sending data such as air pressure, temperature, wind speed back to the ground. Various weather models input this data for use in forecasting.

The United States' contribution to Aircraft Meteorological Data Reports (AMDAR) is called Meteorological Data Collection and Reporting System (MDCRS); it is sometimes also referred to as Aircraft Communications Addressing and Reporting System (ACARS), according to the National Weather Service. MDCRS is paid for by the United States government and the following airlines: American, Delta, Federal Express, Northwest, Southwest, United, and United Parcel Service.

The Transportation Security Administration (TSA) said that the number of passengers going through security year-over-year was roughly the same at the beginning of March. But in the second half of the month, the number of passengers passing through security dropped by nearly 50 percent from 2.5 million down to 1.3 million. Then on Tuesday, April 7, the TSA saw fewer than 100 thousand people go through the checkpoints. That shows definitively the number of flights that aren't leaving the ground.

While there has been a drop in the number of commercial flights, the National Weather Service told NPR that they are still receiving data from overnight cargo and package carriers.

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“We have directed our pilots who have transited affected areas to seek medical attention immediately should they experience flu-like symptoms,” UPS Strategic Communications Director Mike Mangeot said.
“We have directed our pilots who have transited affected areas to seek medical attention immediately should they experience flu-like symptoms,” UPS Strategic Communications Director Mike Mangeot said. (Source: Unsplash)

According to the National Weather Service, more than 3,500 commercial aircraft provide more than 250 million weather observations each year.

One of the weather models that uses this data is the European Centre for Medium-Range Weather Forecasts (ECMWF); many meteorologists call it the European Model for short.

In a statement on April 7, the ECMWF said that the decrease in flights worldwide has led to an 80% drop in weather observations across Europe and a 60% drop worldwide.

A 2019 study found that removing all aircraft data from the ECMWF degrades short-range wind and temperature forecasts at the levels at which planes fly by up to 15%. At the surface, the degradation is small but still statistically significant at 3%.

A 2017 University of Colorado report found that aircraft observations reduced temperatures, winds, and humidity forecast errors by 15 to 30% in the High-Resolution Rapid Refresh (HRRR) model, which runs every hour.

While the drop in weather data from aircraft is significant, other types of observations can fill the void left behind.

Weather balloons are launched from almost 900 locations around the world each day. Twice a day, every day, balloons are launched from 92 sites across the United States. On severe weather days, the National Weather Service may launch extra balloons in order to get more information about ongoing changes in the atmosphere.

Buoys, satellites, and radar can all also help provide pertinent information that can continue to keep forecasts as accurate as possible.

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