Absolute Calibration of Reference Photometers and Total Ozone Spectroradiometers at Izaña July 31 - August 21, 2023

The Izaña Atmospheric Research Center (IARC) in Tenerife, a branch of the Spanish State Meteorological Agency (AEMET) under the Ministry for Ecological Transition and Demographic Challenge (MITECO), has announced that it will serve as a calibration centre for the reference photometers of total ozone spectroradiometers and the AERONET network since the volcanic eruption at the Mauna Loa Observatory on Hawaii Island.

The eruption, which started on November 27, 2022, has severely damaged the infrastructure of the observatory operated by the National Oceanic and Atmospheric Administration (NOAA). As a result, IARC will temporarily take over the role of the global calibration centre for the standard photometers of the network, hosting the instruments from Hawaii until the volcanic emergency is over and the observatory is fully functional again.

The reference instruments for total ozone measurements of the World Meteorological Organization (WMO) Global Atmospheric Ozone Monitoring Network of the Global Atmosphere Watch (GAW) program are also affected by the eruption. These instruments are normally calibrated at Mauna Loa by NOAA and in Toronto by Environment and Climate Change Canada (ECCC) for Dobson and Brewer spectrometers respectively. This year, the calibration campaign will be held at IARC from July 31 to August 21, 2023 with the support of the ATMO-ACCESS project. This is a collaboration between the World Calibration Centers for Dobsons (NOAA) and Brewers (ECCC) and the RBCC-E (Regional Brewer Calibration Center -Europe) of IARC.

IARC is hosting a TNA (TransNational Access) Absolute Calibration campaign, thanks to the support of the ATMO-ACCESS project (Sustainable Access to Atmospheric Research Facilities,[ click here for information on this effort, supported by the European Commission under the Horizon 2020 – Research and Innovation Framework Programme (grant agreement No 101008004)]).

 The AERONET network, coordinated by NASA, is a federal network that has provided AOD (Aerosol Optical Depth) measurements for over 25 years from sun-sky-lunar photometers to monitor aerosol properties and provide satellite validations.

Since 2006, and following the AERONET protocols, field instruments are calibrated by GOA-UVa (Group of Atmospheric Optics-University of Valladolid) in Valladolid, Spain, whereas network reference instruments are calibrated by AEMET at Izaña in Tenerife, Spain, within the AEROSPAIN (AERONET-Spain) network, jointly managed by these two institutions.

The Mauna Loa Observatories (Hawaii) and Izaña Observatory (Tenerife) are the only two centers globally capable of calibrating reference standards in their photometers. Once the reference standards in the photometers are calibrated at these two high-altitude centers, they are sent to secondary calibration centers, located in USA, France, Spain and China, where field photometers can be calibrated using these standards. In this way, until the vocanic emergency subsides, Izaña will be responsible for calibrating the photometers of the Spanish network AEROSPAIN, and the Chinese network CARSNET (as it has been doing in recent years), in addition to the reference photometers of the European network AERONET-Europe and the American network of NASA by means of an ATMO-ACCESS fast-track TNA access.


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