Weather forecasts are a product of science that impacts the lives of many people. They play an important part in economic activity, such as helping businesses and people plan for power production, transportation hazards, and crop protection. A new study conducted by the American Geophysical Union, however, finds that weather forecasts have become less accurate during the Covid-19.
How grounded aircrafts made weather forecast less reliable
Their study, which appeared in AGU’s journal Geophysical Research Letters, explains that the assimilation of meteorological observations from aircraft enhances weather forecasts greatly. Yet, global lockdown from March to May 2020 due to the Covid-19 pandemic has eliminated 50 to 75% aircraft observations and this imperils weather forecasting.
The idea of making scientific atmospheric measurements from aircraft is almost as old as aviation itself. According to the World Meteorological Organization (WMO), their Aircraft Meteorological Data Relay (AMDAR) Panel was established in 1998 for a global application of the inherent observing capability of aircraft. The ADMAR observing system commenced as an operational program that uses existing onboard sensors and systems, which produce nearly half a million observations per day of winds, temperatures, and humidity.
Forecasts meteorologists find it useful and valuable to use ADMAR data. This led to the improvement in applications for prediction and monitoring of weather systems and phenomena, including (1) surface and upper air forecasts of temperature and wind, (2) thunderstorm genesis, severity, and location, (3) low cloud formation, duration, and location, (4) fog formation, duration, and location, (5) jet stream location and intensity, (6) conditions leading to aircraft icing, (7) precipitation amounts and rates, (8) turbulence location and intensity, and (9) wind shear location and intensity.
However, with significantly fewer aircraft in the sky because of pandemic-related travel restrictions, forecasts of meteorological conditions have become less reliable. The study found that the impact of the Covid-19 pandemic in weather forecasts is more pronounced.
The impact of inaccurate weather forecasts
Lancaster Environment Centre’s senior research associate Ying Chen, who is also the lead author of the study, told Science Daily that inaccurate forecasts can affect the economy. Chen highlighted those that will be most affected are those in the agriculture industry and the energy sector. Inaccurate weather forecast moreover affects the stability of the electrical grid. The lead author added that wind turbines depend on the accurate forecast of wind speed as well as energy firms rely on the temperature forecast in estimating what the energy load will be every day.
Chen said that if the uncertainty in weather forecasts goes over the threshold, it can lead to unstable voltage for the electrical grid. If this happens, it can also lead to a blackout, which is probably the last thing that people wanted to see during the pandemic.
The study further mentions the regions that are mostly affected by the drop in aircraft weather observations are those with normally heavy traffic, such as Australia, southeast China, and the United States, and those isolated regions, like Antarctica, Greenland, and the Sahara Desert. A notable exception is Western Europe as its weather forecasts have been fairly unaffected despite the number of flights in the region dropped by 80 to 90% during the lockdown. Chen finds it surprising as he suspects that Western Europe was able to avoid inaccuracies as it has a tightly-packed network of weather stations based on the ground. The region also has balloon measurements that compensate for the lack of planes flying during the lockdown.
Their findings serve as a “good lesson” to tell us that we should have more observation sites, particularly in regions with little data observations, the lead author pointed out. By doing so, it can help the world in the future by buffering the impact of this kind of global emergency.
Global precipitation forecasts have also not been significantly affected as rainfall forecasts relied on satellite observations, the authors added. Yet, most parts of the world have been relatively dry between March to May so the lead author cautioned that precipitation forecasts may suffer as monsoon and hurricane seasons arrive.
The ADMAR program
The ADMAR program includes more than 40 commercial airlines and 3,500 aircraft that typically provide over 700,000 meteorological reports every day. When the study authors compared the accuracy of weather forecasts between March to May 2020 to the same periods in 2017, 2018, and 2019, they found that the 2020 weather forecasts were less accurate for air pressure, relative humidity, and temperature. This is even though weather forecasts were more reliable in February 2020 compared in the past years.
They mentioned that when there are a greater number of meteorological observations, forecast models are more accurate. On the other hand, meteorological observations are greatly diminished when fewer planes are flying in the air as was the case during the global lockdown. The authors likewise found that wind speed and surface pressure forecasts were not affected in the short term or within 1 to 3 days but were less accurate for the long term or 4 to 8 days forecasts.
Coronavirus air travel: statistics
The travel curbs have turned the air travel industry as one of the biggest casualties of the Covid-19 pandemic. According to the travel review platform Condé Nast Traveler, at least half the planes in the world were grounded in late March. Airlines worldwide are losing $1.6 billion per day as part of the economic impact of the health crisis. In a survey of 1,250 Americans, one in five or 20% don’t plan to travel for the rest of the year other than for business or essential reasons. Only 11% of Americans aged 18 to 25 said they would wait until 2021 to take their next trip.
Database company Statista also shares that for the week starting March 2, the global flight frequency was down by 7.9%. In the week of March 30, Spain’s flight frequency was down by 88.5%. Other countries most affected in the same period were Hong Kong (-88.3%), Germany (-88.6%), and Singapore (-90.8%). As of July 6, the number of scheduled flights worldwide was down by 55.3% compared to the week of July 8, 2019. Before the pandemic, the global aviation industry was at its steady pace across countries.
The longer the weather forecasters lack aircraft observation data, the more our weather forecasts will be affected. Just as the American Geophysical Union researchers have suggested in their study, weather data sources need to be diversified, particularly in regions that depend heavily on commercial aircraft.