How Coronavirus is Affecting Weather Forecasting Skill
The coronavirus continues to affect millions across the globe, and one of the effects it’s having keeping people home. That has therefore had an effect on travel by airplane, for example.
In the United States, the Transportation Security Administration, or TSA, reported that only 87,543 passengers were screened at the nation’s airports. Last year on the same day, more than 2.2 million people passed through security checkpoints, making this about a 96% reduction in travel.
That significant decrease in travel is forcing hundreds of airplanes to be grounded in the U.S. and around the world, which is having some effects on weather forecasting skill.
Brian McNoldy, a senior research associate at the University of Miami’s Rosenstiel School of Marine and Atmospheric Science, studied the positive impacts aircraft and satellite observations have on weather forecasting in his master’s thesis completed in 2001.
McNoldy claims that the data collected by airplanes “allows airport crews to make icing forecasts and it allows weather forecasters to improve predictions of cloud formation and rainfall potential in nearly real-time. The data can even be used as input to computer forecast models…”
Weather data, such as water vapor and wind measurements, collected from aircraft is directly assimilated, or factored, into computer models that help meteorologists forecast the weather.
McNoldy acknowledges that “aircraft provide the unique ability to actually go to the place in the atmosphere where one desires a measurement.” There are weather observations taken from the ground and from satellites in space, but the gap that happens in between these two regions is taken by aircraft, helping to better sample the atmosphere and to improve forecasting abilities.
Unfortunately, these beneficial weather soundings from in the sky have taken a hit due to the large reduction in flights thanks to the coronavirus. Some meteorologists and forecasting agencies have concluded that this has had an effect on weather prediction skill while others claim it has not.
According to the United States’ National Oceanic and Atmospheric Administration, or NOAA, NOAA spokesperson Lauren Gaches says, "While there is a reduction of commercial passenger flights, we still receive valuable aircraft data from overnight cargo and package carriers. We also collect billions of Earth observations from other sources that feed into our models, such as weather balloons, surface weather observation network, radar, satellites and buoys."
Others, like the World Meteorological Organization (WMO), disagree, saying that it's "concerned about the impact of the COVID-19 pandemic on the quantity and quality of weather observations and forecasts."
The WMO has mentioned that “the [Aircraft Meteorological Data Relay programme] observing system produces over 800,000 high-quality observations per day of air temperature and wind speed and direction…”
Now the data is the most important factor when determining if there is in fact an effect.
According to the European Centre for Medium-Range Weather Forecasts (ECMWF), “studies have shown that removing all aircraft data degrades the short-range wind and temperature forecasts at those levels by up to 15%, with significant degradations at all forecast ranges up to seven days. There is a smaller, but still statistically significant, impact on near-surface fields, up to 3% on surface pressure.”
The ECMWF has made models in the past to examine how aircraft data affects forecasting, and found 12-hour forecasts to be about 10% worse in the upper-levels of the atmosphere where planes fly.
There is no clear or substantial sign that the reduction in flights is having a direct impact on weather forecasting skill, but there are still some suggestions based on the modeling of a situation like this that show to a minor reduction in proficiency.