1,2,1,4,1,1- 1Physical and Meteorological Observatory Davos and World Radiation Center (PMOD/WRC), Davos Dorf, Switzerland (team-office@pmodwrc.ch)
- 2Institute of particle physics and astrophysics, ETH Zurich, Zurich, Switzerland (nkalas@phys.ethz.ch)
- 3Izaña Atmospheric Research Center, State Meteorological Agency, Santa Cruz de Tenerife, Spain (ciai@aemet.es)
- 4Group of Atmospheric Optics, University of Valladolid, Valladolid, Spain (angel@goa.uva.es)
- 5CNRS, LOA – Laboratoire d'Optique Atmosphérique, University of Lille, Lille, France (loa-secretariat@univ-lille.fr)
Aerosol optical depth (AOD) describes the overall direct effect of the aerosol column direct on solar radiation, which makes it a particularly important parameter for Earth energy budget related studies. Various instrument networks measure AOD worldwide such as the Aerosol RObotic NETwork (AERONET), the Global Atmospheric Watch Precision Filter Radiometer (GAW-PFR) network (Kazadzis et al., 2018) and SKYNET.
PMOD/WRC is designated from the World Meteorological Organization (WMO) and the International Bureau of Weights and Measures to maintain the world reference AOD standards and serve as the central calibration laboratory under the WMO’s Global Atmosphere Watch Program. The reference AOD dataset is provided by three precision filter radiometers (PFR). PMOD/WRC aims at standardisation and homogenisation of AOD reference scales. Also to improve the calibration, processing algorithms and consistency of long‐term measurements. Under CARS (Calibration of Aerosol Remote Sensing) of ACTRIS, PMOD/WRC aims to establish the traceability link between the AOD measured by ACTRIS instruments to the WMO reference and thereby to the SI.
In accordance with this goal, in this work we focus on the comparison of AOD measurements from CIMEL and PFR traveling reference standards at the three ACTRIS/CARS and AERONET calibration sites:
- Izaña Observatory, Tenerife, Spain (28.3 N, 16.5 W, 2401 m above sea level). Parallel measurements at Izaña started in 2002.
- The Observatoire de Haute-Provence (43.93 N, 5.71 E, 680 m a.s.l.), France. The PFR observations started in 2020.
- The University of Valladolid, Spain (41.66 N, 4.70 W, 705m a.s.l.). PFR observations started in June of 2022.
We also assess the performance of the intercomparisons according to the WMO limits for traceability and the AOD instrument uncertainties.
Acknowledgements
This work was supported by the ACTRIS-CH (Aerosol, Clouds and Trace Gases Research Infrastructure – Swiss contribution) funded by the State Secretariat for Education, Research, and Innovation, Switzerland.
The authors acknowledge the support of the Spanish Ministry for Science and Innovation to ACTRIS ERIC.
References
Kazadzis, S., Kouremeti, N., Nyeki, S., Gröbner, J., and Wehrli, C.: The World Optical Depth Research and Calibration Center (WORCC) quality assurance and quality control of GAW-PFR AOD measurements, Geosci. Instrum. Method. Data Syst., 2018.
WMO: Aerosol Measurement Procedures, Guidelines and Recommendations, WMO No 1177, 2016.
How to cite: Karanikolas, A., Kouremeti, N., Barreto, A., Toledano, C., Goloub, P., Gröbner, J., and Kazadzis, S.: AOD long term comparisons of CIMEL and PFR measurements at the ACTRIS sun-photometer calibration sites, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18332, https://doi.org/10.5194/egusphere-egu26-18332, 2026.
