Weather forecasts are not immune to COVID-19
The World Meteorological Organisation (WMO) is concerned about the impact COVID-19 is having on international weather forecasts and climate monitoring.
In late March, the European Centre for Medium-Range Weather Forecasts (ECMWF) released data showing that aircraft-based weather observations had declined over the previous month. This drop was a result of mass flight cancellations around the world in response to the COVID-19 pandemic.
Image: This graph shows a reduction in the number of aircraft-based observations (reports) over Europe received by the ECMWF during March 2020. Between March 3rd and 23rd, the ECMWF reported a reduction of 65% over Europe and 42% globally. Source: ECMWF
Now, the WMO has revealed that the degradation of weather observations in recent weeks wasn't just confined to the air.
Surface-based weather observations have also taken a dive in some parts of the world, particularly in developing countries, where observing is still a manual process. Some countries have even stopped reporting their observations altogether.
Image: Thredbo Top Station, Australia's highest weather station
The most obvious impacts of COVID-19 on the global weather observing system have so far related to air-traffic and manual reporting. However, if the pandemic continues for too long, even automated parts of the system may not be immune.
"If the pandemic lasts more than a few weeks, then missing repair, maintenance and supply work, and missing redeployments will become of increasing concern," said the WMO.
So, what does this mean for weather forecasts and climate monitoring around the world and here in Australia?
A reduction in the quality and quantity of weather observations is likely to impact the performance of the computer models that underpin modern weather forecasting. These 'numerical weather prediction' (NWP) models use real-time observations from the world's atmosphere, land and oceans to create a starting point for their forecasts. If these observations are compromised, the accuracy of the starting point will be diluted and the model's overall performance will degrade.
The extent of COVID-19's impact on weather forecast accuracy will depend on how badly it disrupts observations in the coming weeks and months.
"At the present time, the adverse impact of the loss of observations on the quality of weather forecast products is still expected to be relatively modest. However, as the decrease in availability of aircraft weather observations continues and expands, we may expect a gradual decrease in reliability of the forecasts," said Lars Peter Riishojgaard, Director, Earth System Branch in WMO's Infrastructure Department.
"The same is true if the decrease in surface-based weather observations continues, in particular if the COVID-19 outbreak starts to more widely impact the ability of observers to do their job in large parts of the developing world. WMO will continue to monitor the situation, and the organization is working with its Members to mitigate the impact as much as possible," he said.
WMO figures show that over 10,000 manned and automatic surface weather stations, 1000 upper-air stations, 7,000 ships, more than 1000 buoys and nearly 70 satellites currently measure key parameters of the atmosphere, land and ocean every day.