The outbreak of the coronavirus COVID-19 is having an enormous impact on our daily lives. Nearly 20% of the global population are living in some form of lock-down and no longer travelling or commuting to work, via road, rail or air.
The disruption to the aviation industry has been immense, with airlines grounding their planes. Lufthansa, Europe’s biggest carrier, cut flights by 50% in April. As the pandemic continues to grip the globe and more countries impose travel restrictions, the German airline has indicated that it may need to thin schedules by 90%. It’s likely that the airline industry could be very different when the world re-emerges from the economic impact of the coronavirus, whether there are fewer airlines and / or the number of routes flown is reduced.
The aviation industry provides an important role for the weather community by collecting weather observations (e.g. wind speed and temperature). The airline industry makes available around 230,000 aircraft observations per day via the World Meteorological Organization’s communication system (WMO - GTS) in normal times.
Global weather forecasting centres, such as ECMWF (also known as the ‘European Centre model’), United States’ National Weather Service and the UK’s Met Office, collect an understanding of the atmosphere so that they can inform the starting conditions of their weather models.
ECMWF conducted test model runs in 2019 to evaluate the efficacy of aircraft reports in their models. According to their report, “Sensitivity studies at ECMWF 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.”
European Aircraft Meteorological Data Relay (AMDAR) coverage for 2 March 2020
European Aircraft Meteorological Data Relay (AMDAR) coverage for 23 March 2020
Many global weather centres are now evaluating how they can mitigate the loss of weather data provided by the airlines. Some weather forecasting centres are increasing the amount of satellite data they use and there are calls to increase the number of radiosonde flights (balloons filled with helium gas, carrying weather instruments) - both of which have their limitations.
Whilst satellite data provides a lot of information on temperature and humidity fields, it provides less data on wind fields. Plus, a closer look at satellite data reveals a gap in the planetary boundary layer (PBL), i.e. the first 1 to 2 km above ground level (AGL). This is crucial because weather phenomena such as fog, low cloud and storms form at this altitude.
Radiosondes do offer an alternative. However, it’s difficult for national weather centers to increase the number of radiosonde flights, as the equipment they carry can be expensive to manufacture, they’re filled with helium gas that is becoming a scarce natural resource and radiosondes are commonly lost after deployment, as they are carried away with the wind.
Meteomatics’ weather drones fill the observation gap in the PBL
Weather drones offer global weather forecasters and other intersted parties a reliable and scientifically robust method of collecting weather observations. Meteomatics, an international weather company based in St Gallen, Switzerland, manufactures its own weather drones, called ‘Meteodrones’. Meteodrones are engineered specifically for collecting weather observations and can operate in some of the most challenging weather conditions (e.g. severe thunderstorms – test flight completed with NOAA’s National Severe Storms Laboratory in the US).
The challenges of operating a drone in a wide variety of weather situations and in urban/remote locations have pushed the boundaries of drone design. Battery performance, an automatic recovery system and heating elements in the blades to prevent icing are just some of the unique capabilities of Meteodrones.
Single flight visualised in SKEW-T log-P diagram, 20th March 2020, at a location in Switzerland
Single flight visualised in SKEW-T log-P diagram, 22nd March 2020, at a location in Switzerland
In fact, Meteomatics is already ingesting weather data into limited area models (such as WRF), without implementing any additional forward observational operators. The data can be directly assimilated like any radiosonde data.
Depending on the topography and the height of the mission, the radius of influence of the Meteodrone-gathered data can be 15 to 45 km. Existing 4d-nudging, 4d-VAR or Ensemble Kalman filter routines can also be used to assimilate the drone data into the initial state of the weather model.
In order to estimate meteorological parameters in the lower atmosphere, the atmospheric lapse rates are traditionally calculated using weather station data. However, these estimates are prone to errors. The Meteodrone data enable the measurement of actual lapse rates, which can then be applied to other regions as well.
Initialising limited area model using Meteomatics’ weather drone data
Global forecasting centers are already purchasing weather drones, with Meteomatics supplying NOAA (United States National Oceanic and Atmospheric Administration). Meteomatics expects to see more national meteorological services move towards weather drone observations, but demand could accelerate as organisations concerned with the atmosphere look to mitigate the impacts of the coronavirus.
Meteomatics has published a white paper that contains further details on the capabilities of its drones and a number of case studies, accessible here.
Please contact Meteomatics if you would like any further information