Set-up & scientific goals
Between 13 and 30 September of 2021 the RITA-1 intensive measurement campaign took place at and around the Cabauw observatory and the city of Utrecht. The acronym RITA-1 stands for “Ruisdael Land-Atmosphere Interactions Intensive Trace-gas and Aerosol measurement campaign – Nitrogen and Aerosol Budget Closure experiment” and it involved all partners of the Dutch Ruisdael consortium. Besides the stationary measurement activities at Cabauw the campaign included two additional mobile measurement platforms, being a fully equipped TNO measurement truck for in-situ observations of a suit of trace gases and aerosol characteristics, and the SkyArrow research aircraft (PH-WUR) carrying measurement instrument for air sampling and in-situ greenhouse gas observations. The combined observations of the stationairy Cabauw site and the mobile platforms on the ground and in the air provide a unique opportunity for regional 3D source mapping of GHGs and pollutant trace gas species. The main objective of the RITA-2021 campaign was to improve our understanding of boundary-layer dynamics and cloud formation, the nitrogen budget, and fluxes of GHGs in the ~30×30 km Cabauw footprint combining stationary and mobile observations and 3 different versions of the high-resolution Dutch Atmospheric Large-Eddy Simulation model (DALES).
The main campaign activities included:
- The ammonia flux measurement intercomparison experiment at Cabauw involving 3 different novel flux measurement devices.
- The WUR SkyArrow aircraft (PH-LAB) CO2-flux and in-situ CO2, CH4, N2O, and water vapor observations in the boundary layer and vertical profiles over Cabauw.
- The TNO measurement truck for regional source mapping of GHGs and pollutant trace gas species.
- The Convective Momentum Transport (CMT) experiment at Cabauw using intensified CMTRACE observations (WindCube, Dual-Freq cloud radar (CLARA), mobile cloud radar (MARA)) to provide observational evidence of CMT.
- The aerosol optical column and budget closure experiment combining LIDAR observations, aerosol pre-cursor and composition measurements and detailed meteo at Cabauw.
Participating institutes & responsible scientists
- Wageningen University & Research, The Netherlands (WUR): Ronald Hutjes (SkyArrow CO2 fluxes).
- University of Groningen, Centre for Isotope research Groningen, The Netherlands (RUG): Bert Scheeren, Steven van Heuven (SkyArrow Licor CO2 en CH4 flight profiles and vertical profiles; SkyArrow Active AirCore profiles for CO2, CH4, CO, N2O).
- Royal Netherlands Meteorological Institute, De Bilt, The Netherlands (KNMI): Fred Bosveld (Scintillometer path intercomparison experiment); Arnoud Apituley (Aerosol remote sensing Cabauw).
- Dutch Organization for Applied Scientific Research (TNO): Arjan Hensen (TNO truck tracks of in-situ CO2, CH4, N2O, CO, NOx, NH3, e.a.); Bas Henzing (In-situ aerosol observations at Cabauw).
- Rijksinstituut voor Volksgezondheid en Milieu, Bilthoven, The Netherlands (RIVM): Daan Swart (Ammonia flux intercomparison experiment).
- Imstitute for Marine and Atmospheric research Utrecht, Utrecht University, The Netherlands (IMAU): Rupert Holzinger (ACSM systems for aerosol composition at Cabauw).
- Vrije Universiteit van Amsterdam (VU): Katharina Heimerl, Sander Houweling (FTS-remote sensing vertical profiles of CO2 en CH4).
- Delft University of Technology (TUD): Louise Nuijens, Pier Siebesma (Cloud profiling & CMT observations).
Impressions of the RITA-2021 campaign
The WUR Sky Arrow research aircraft ready to take off at Hilversum airport.
Impressions of the Cabauw observatory, the SkyArrow research aircraft passing by, and the TNO measurement truck stationed at Cabauw.
The ammonia-flux experiment during RITA-2021 (left panel) and the portable Fourier transformation infrared spectrometer (right panel) to measure the column integrated mixing ratios of the trace gases CO2, CH4 and CO from the spectral absorption of direct sun light. In the background one can see the SkyArrow research plane starting a vertical profile measurement over the Cabauw site.
The TNO measurement truck underway (left panel) and from the insight (right panel).
Schematic of the RITA-2021 SkyArrow flight track of flight 2 on 14 September 2021 around Cabauw and the city of Utrecht. The white square represents a 50×50 km surface area.
Scientific output
Selected (preliminary) results from the RITA-1 2021 campaign:
On September the 26th the La Palma vulcanic dust plume was detected over Cabauw at an altitude between 5 and 6 km high by the Caeli Raman lidar system stationed at Cabauw (by courtesy of Arnoud Apituley, KNMI). The Caeli system provides continuous day and night high temporal and spatial resolution profiles of aerosol and humidity. Data is available here.
EM27 FTIR spectrometer total column-averaged dry-air mole fraction of CO2 during the RITA-2021 campaign period (preliminary data by courtesy of Katharina Heimerl, VU).
Measuring dry deposition of Ammonia with miniDOAS 2.2 at night at the Cabauw site (photo by courtesy of Daan Swart, RIVM).
MiniDOAS 2.2 preliminary emission (positive) and deposition (negative) fluxes of NH3 at Cabauw during September 2021 (data by courtesy of Daan Swart, RIVM).
Overview of preliminary Aerosol Chemical Speciation Monitor (ACSM) results showing the anorganic composition of PM2.5 aerosols observed at Cabauw during the RITA-2021 campaign (data by courtesy of Rupert Holzinger, IMAU, Utrecht University).
Example of a DALES model high resolution simulation for the area around Cabauw of total column (0-1500 m) integrated CH4 mixing ratios showing individual plumes from point sources such as landfills (image by courtesy of Sander Houweling, VU).
Between September 1 and 30 a total of 34 radiosondes were launched at the KNMI (at 12 and 24 hours) providing vertical profiles of wind direction and wind speed. Even though the KNMI (De Bilt) is 23 km away from the experimental site Cabauw we find that wind speed and direction profiles from radar and lidar system at Cabauw are very comparable to the radiosonde results (data by courtesy of Louise Nuijnes (TUD), and Arnoud Apituley (KNMI)).
Selected peer-reviewed publications
Liu, X., Henzing, B., Hensen, A., Mulder, J., Yao, P., van Dinther, D., van Bronckhorst, J., Huang, R., and Dusek, U.: Measurement report: Evaluation of the TOF-ACSM-CV for PM1.0 and PM2.5 measurements during the RITA-2021 field campaign, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2023-967, 2023.
Swart, D., Zhang, J., van der Graaf, S., Rutledge-Jonker, S., Hensen, A., Berkhout, S., Wintjen, P., van der Hoff, R., Haaima, M., Frumau, A., van den Bulk, P., Schulte, R., van Zanten, M., and van Goethem, T.: Field comparison of two novel open-path instruments that measure dry deposition and emission of ammonia using flux-gradient and eddy covariance methods, Atmos. Meas. Tech., 16, 529–546, https://doi.org/10.5194/amt-16-529-2023, 2023.
Schulte, R. B., Vilà-Guerau de Arellano, J., Rutledge-Jonker, S., van der Graaf, S., Zhang, J., and van Zanten, M. C.: Observational relationships between ammonia, carbon dioxide and water vapor under a wide range of meteorological and turbulent conditions: RITA-2021 campaign, Biogeosciences, 21, 557–574, https://doi.org/10.5194/bg-21-557-2024, 2024.
An overview of Ruisdael scientific publications can be found here.
Data products and data availability
For specific data products or additional info please contact the specific scientific PIs.
Ruisdael data can be found here.