UAS-DC Scope and Participation

Scope of the UAS Demonstration Campaign

The requirements of UAS-DC participants were determined by the scope of the campaign, which is described in detail in the UAS-DC description and summarized below.

The over-arching aim is described in the UAS-DC project theme:

WMO will coordinate a global demonstration project on the utility and efficacy of Uncrewed Aircraft Systems (UAS) to routinely and operationally contribute to the WIGOS Global Basic Observing Network (GBON).

The scope of the campaign was based on key requirements and expectations derived from the theme and the aims.

Element of scope	Scope (as implemented)
Observing period	8 months, from 1 March to 31 October 2024
3 Special Observing Periods (SOPs)	Periods in which participants were asked to make observations, where possible, with higher temporal resolution (more frequent flights and observations) and wider coverage (more sites): 1. April 2024, the whole month, with high priority on the week starting 8 April (total solar eclipse of 8 April) 2. 28 July – 14 August 2024, overlapping with the Paris 2024 Olympic Games 3. 8–13 September 2024, overlapping with the ISARRA 2024 flight week and the SCALES campaign (mesoSCALES and microSCALES) in Tulsa, Oklahoma, USA
Participants	Participant Operators: WMO Member, research and private UAS operators. In total, 44 operators from 13 countries took part on a voluntary basis, including national meteorological and hydrological services, research institutions and commercial companies. Participant Data Users: Member data users, NWP centres (including ECMWF, DWD, MeteoSwiss and NOAA GSL) and research data users. Other stakeholders: WMO, INFCOM, ICAO and national civil aviation authorities.
Geographical scope	Open globally to participants in all regions where UAS can be flown in compliance with national airspace regulations. In practice, all observations were made in the Northern Hemisphere, mostly in Europe and the United States, with sites in Asia (Japan, Russia and Taiwan). The northernmost site was Ny-Ålesund, Svalbard. The southernmost observations were made by high-altitude balloons over the Atlantic Ocean west of Cabo Verde.
UAS types	Planned: autonomous or remotely piloted small copter or fixed-wing UAS, and automated or remotely piloted high-altitude fixed-wing UAS. Flown: multirotor (about 82 % of logged flights), fixed-wing (about 10 %), VTOL (about 2 %) and balloon-launched dropsondes (about 5 %), plus balloon-launched gliders and long-duration high-altitude balloons. Maximum altitudes ranged from 100 m to 9,000 m above mean sea level (MSL) for UAS, and up to 23,177 m MSL for balloon-based platforms.
Observing locations and modes	Observations from all locations and modes, including but not limited to: • Oceanic atmospheric boundary layer (ABL): vertical profiles of the ABL from stationary or moving platforms • Remote land, mountain, coastal and cryosphere observations and vertical profiles • Upper-troposphere and lower-stratosphere observations • Testbed observations and vertical profiling • Symbiotic observations collected by private UAS performing another primary mission (e.g. package delivery) Most flights stayed below about 500 m MSL, although a substantial number exceeded 1,000 m MSL.
Reported variables	Required: air temperature, air pressure and relative humidity. These were reported in nearly all uploaded files. Additional: horizontal wind speed and direction were reported in more than 90 % of files. A small fraction of files also contained vertical wind, aerosol concentrations, and O₃, NH₃, CO, NO₂, H₂S, SO₂ and total volatile organic compounds. About 1 % of files contained turbulence data (turbulent kinetic energy and eddy dissipation rate).
Data provision	Operators were welcome to provide UAS profiles throughout the campaign and were encouraged to concentrate their effort on the SOPs. 1. Continuous, routine data provision: observations of the required variables, with supporting metadata, at least once per day on at least 4 days per week. 2. Near-real time: preferably within 30 minutes of the observation and no later than 3 hours afterwards. In practice, more than 80 % of files were uploaded within one hour of acquisition. 3. Standard data format: data were submitted as NetCDF files in the WMO-CF UAS Trajectory format to a central repository on Amazon Web Services, operated by Synoptic Data PBC. The files were converted automatically to BUFR and distributed to subscribed data users through the WIS 2.0 Global Broker. Converting NetCDF files that contain multiple profiles to BUFR was not supported. Total contribution: more than 13,000 flights and more than 13,100 data files.

Summary of Requirements of Participants

To ensure that participants could best meet the scope and aims of the campaign, specific requirements were set for the role each participant played.

Participants fell into two main categories:

Participant UAS Operator: provided UAS observations in accordance with the scope above.
Participant Data User: received and used the UAS data to determine data quality and impact.

UAS Operator requirements	Data User requirements
General requirements 1. Adhere to the UAS-DC Data Policy. 2. Endeavour to provide continuous, routine data for at least 1 month during the observing period. 3. Endeavour to take part in at least one of the three Special Observing Periods. 4. Submit participant reports that WMO may use as input to the final report of the UAS-DC. Operators also recorded each flight in the Daily Operator Log (1,414 entries) and completed the Post-Campaign Report (27 operators). 5. Make observations available to Participant Data Users through the central data repository in the standard UAS data format. 6. Provide a standard Participant Operator Report and input to the reports on demonstration results and outcomes. Requirements for UAS operations 1. Endeavour to provide continuous, routine data for at least 1 month during the observing period and during at least one SOP. 2. Endeavour to provide one or more required atmospheric variables, with supporting metadata, under continuous, routine data provision throughout at least one month of the campaign. Preferably do so during at least one SOP, in at least one of the modes of operation and in one or more of the observing locations. 3. Provide data in the standard format to the central data repository in near-real time. 4. Where and when possible, compare measurements with intercomparison systems (radiosondes, towers, Doppler lidars, etc.). 5. Endeavour to operate UAS according to the UAS-DC Guidance for UAS Operators.	1. Adhere to the UAS-DC Data Policy. 2. Commit to taking part in assessing observation data quality and/or impact on forecasts. 3. Operate an NWP system with which the quality of UAS data and their impact on forecasts can be assessed. 4. Endeavour to assess the quality and, if possible, the forecast impact of the data provided by UAS operators. 5. Be able to process and use the UAS-DC standard data format for requirements 2–4 above, and evaluate the usability of the data format for operational real-time data exchange in NWP systems. 6. Submit reports to

UAS Operator requirements

Data User requirements

General requirements
1. Adhere to the UAS-DC Data Policy.
2. Endeavour to provide continuous, routine data for at least 1 month during the observing period.
3. Endeavour to take part in at least one of the three Special Observing Periods.
4. Submit participant reports that WMO may use as input to the final report of the UAS-DC. Operators also recorded each flight in the Daily Operator Log (1,414 entries) and completed the Post-Campaign Report (27 operators).
5. Make observations available to Participant Data Users through the central data repository in the standard UAS data format.
6. Provide a standard Participant Operator Report and input to the reports on demonstration results and outcomes.

Requirements for UAS operations
1. Endeavour to provide continuous, routine data for at least 1 month during the observing period and during at least one SOP.
2. Endeavour to provide one or more required atmospheric variables, with supporting metadata, under continuous, routine data provision throughout at least one month of the campaign. Preferably do so during at least one SOP, in at least one of the modes of operation and in one or more of the observing locations.
3. Provide data in the standard format to the central data repository in near-real time.
4. Where and when possible, compare measurements with intercomparison systems (radiosondes, towers, Doppler lidars, etc.).
5. Endeavour to operate UAS according to the UAS-DC Guidance for UAS Operators.

1. Adhere to the UAS-DC Data Policy.
2. Commit to taking part in assessing observation data quality and/or impact on forecasts.
3. Operate an NWP system with which the quality of UAS data and their impact on forecasts can be assessed.
4. Endeavour to assess the quality and, if possible, the forecast impact of the data provided by UAS operators.
5. Be able to process and use the UAS-DC standard data format for requirements 2–4 above, and evaluate the usability of the data format for operational real-time data exchange in NWP systems.
6. Submit reports to