The lack of commercial flights due to the Covid-19 crisis is not only a problem for the aviation industry but also has weather forecasters concerned.
Sensors, computers and communications systems onboard commercial jets automatically collect and transmit meteorological observations to ground stations, which have been curtailed by the sharp decline in air traffic.
“In-flight measurements of ambient temperature and wind speed and direction are a very important source of information for both weather prediction and climate monitoring,” the World Meteorological Organization states.
The Geneva-based UN specialised agency says 43 airlines and several thousand aircraft contribute to the Aircraft Meteorological Data Relay programme (AMDAR), producing over 800,000 daily observations such as air temperature, wind speed and direction, humidity and even turbulence.
In Europe, contributing airlines include Aer Lingus, Air France, British Airways, easyJet, Finnair, KLM, Lufthansa, Turkish Airlines, SAS and Wizz Air.
However, with airlines worldwide grounding most of their fleets due to coronavirus-related travel restrictions, those observations are also down.
WMO says that in many parts of the world, over Europe and the USA in particular, the number of observations from aircraft is down anywhere from 50% to over 80%.
Lars Peter Riishojgaard, director, Earth System Branch in WMO’s Infrastructure Department, said: “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.”
Besides aircraft observations, the WMO also uses satellites, ground stations, surface monitoring systems and marine-based platforms to gather meteorological data. To try and compensate for the lack of aircraft observations, some WMO member states, especially in Europe, are sending up more radiosondes on weather balloons to take meteorological readings.
