• Variables: profiles of aerosol extinction and backscattering, lidar ratio, particle linear depolarization ratio, Ångström exponents; geometrical boundaries of aerosol layers and layer-mean optical properties, columnar spectral aerosol optical depth and sky radiance, particle microphysical and radiative properties
  • High-power aerosol lidar

Optimum: 3-l Raman/HSR lidar with polarization capability (355, 532, 1064 nm), continuous operation –Minimum: 1-l Raman/HSR lidar with polarization (355 or 532 nm), operated on fixed schedule

  • Automatic sun/sky and moon photometer

Optimum: Sun/sky and moon photometer –Minimum: Sun/sky photometer

Two instruments are required.

Data are centrally processed at the associated CFs in RRT*.

*RRT = real real-time, within 3 hours after data acquisition


  • Variables: number size distribution (0.01–0.8 µm + other size ranges), light scattering & backscattering coefficients, light absorption coefficient & equivalent black carbon concentration, mass concentration of particulate organic & elemental carbon, particulate elements, particulate organic tracers, non-refractory organic and inorganic aerosols, CCN
  • Minimum instrument set: 3 mandatory + at least 2 specializing variables (out of 9)
    • Mobility Particle Size Spectrometer
    • Integrating Nephelometer
    • Absorption Photometer
    • Thermo-optical method on quartz filters
    • Aerodynamic & Optical Particle Size Spectrometer
    • Condensation Particle Counter
    • Filter-based XRF/PIXE/ICP_OES/ICP_MS
    • Filter-based IC, GC-MS HPLC-MS, LC/MS
    • Cloud Condensation Nuclei Counter
    • Aerosol Mass Spectrometer
    • PSM-CPC
    • Scanning PSM, (N)AIS, N-MPSS
  • Variables: liquid water content (LWC), effective droplet diameter (Deff), cloud droplet number concentration and size distribution, ice crystal number concentration and size distribution, ice nucleating particle (INP), number concentration and temperature spectra, bulk cloud water chemical composition
  • Minimum instrument set: 2 mandatory (LWC and Deff) + at least 2 specializing variables
    • cloud probes
    • scattering cloud probes
    • imaging cloud probes
    • on-line INP instruments
    • off-line INP analysis of aerosol samples
    • Bulk cloud water collectors and off-line chemical analysis

Data processing at NFs. Data delivery at least yearly.

  • Variables: vertical cloud structure, cloud fraction, cloud and aerosol target classification, liquid water content, ice water content, drizzle properties (size distribution, water content, water flux), dissipation rate of TKE (turbulent kinetic energy), liquid water path, integrated water vapour path, temperature and humidity profiles
  • Doppler cloud radar (with polarization)
    Optimum: full Doppler spectrum, together with first 3 moments
    Minimum: mean Doppler velocity
  • Aerosol lidar
    –Optimum: high-power lidar with polarization capability
    –Minimum: low-power lidar/ceilometer (for liquid-cloud detection)
  • Microwave radiometer
    –Optimum: multi-channel and scanning
    –Minimum: dual-frequency
  • Doppler lidar (for optimum setup only).

Three instruments are required. All instruments operated continuously.

Data are centrally processed at the associated CF in RRT.

  • Variables: Nitrogen oxides (NO and NO2), volatile organic compounds (non-methane hydrocarbons, oxygenated VOCs, biogenic VOCs, extremely low volatile organic compounds) - Optimum: NO, NO2, ozone and relative humidity, J(NO2), NMHC in the C2-C9 range (about 30 compounds), OVOCs in the C1-C5 range (about 10 compounds), BVOCs, aerosol precursors
    - Minimum: NO, NO2, ozone and relative humidity (if needed for analysis), at least 6 VOCs
  • NOx - Chemiluminescence detection (CLD)
    - Photolytic conversion with Cavity Attenuated Phase Shift (CAPS) instrument
    - Other NO2-specific techniques
  • VOC
    - Gas chromatography (GC) systems equipped with flame ionization detection (GC-FID) and/or
    - mass spectrometry (GC-MS), on-line or off-line
    - Alternatively: Proton transfer reaction–mass spectrometry (e.g. PTR-MS)

Data processing at NFs.

Data delivery at least yearly. NRT/RRT recommended.

  • Variables: ozone (O3) column, partial column and vertical profile; nitrogen dioxide (NO2) column, partial columns and lower tropospheric profile; formaldehyde (HCHO) column and lower tropospheric profile; ethane (C2H6) column; ammonia column (NH3)
  • Fourier transform Infrared Spectrometers (FTIR)
    Optimum: double FTIR (700–5000 cm-1, KBr beamsplitter, InSb and MCT detectors)
    Minimum: single FTIR (1900–4100 cm-1, CaF2 beamsplitter, InSb detector; no O3 meas.)
  • UVVIS (DOAS) spectrometersOptimum: UVVIS/MAX-DOASMinimum: UVVIS/zenith-sky
  • O3 DIAL for optimum setup only -Optimum: double FTIR + MAX-DOAS or single FTIR + O3 DIAL + MAX-DOAS -Minimum:double FTIR or single FTIR + UVVIS/zenith-sky

Data processing mainly at NFs (for UVVIS central processing planned).

Data delivery required within 3 months. NRT delivery recommended.