TNA12: Access to AERONET-EUROPE Calibration Service

WP Leader: Philippe Goloub


Name of the infrastructure: AERONET-EUROPE Calibration Service
Location (town, country): The infrastructure is composed of separate but complementary installations. The leading and entrance installation is PHOTONS observatory, located in CNRS-LOA (Laboratoire d’Optique Atmospherique), University of Lille 1, Villeneuve d’Ascq city (France) coupled with a Meteofrance platform located in Carpentras city, France. The other installations are in Spain (CSIC/IZANA) and GOA-UVA (Groupe of Atmospheric Optics, University of Valladolid).

Web site address:
Legal name of organisation operating the infrastructure: Centre National de la Recherche Scientifique
Location of organisation (town, country): Paris, France
Annual operating costs (excl. investment costs) of the infrastructure (€): 408.949
(188.716 € for CNRS, 117.513 € for CSIC/IZANA, 102.720 € for GOA-UVA)

Description of the infrastructure:
AERONET (AERosol RObotic Network) is a ground-based standardized automatic sun/sky-photometer network devoted to characterization and monitoring of aerosol properties as well as water vapour water content. To enable AERONET network expansion, alternative calibration centers have been developped in Europe under the leadership of France, primarily by CNRS-LOA in France (Laboratoire d’Optique Atmospherique, Lille University) operated by PHOTONS national observatory, then in Spain by GOA (Grupo de Óptica Atmosférica, Valladolid) and by AEMET (CSIC) at Izaña Observatory, Tenerife Island. The main goal of the AERONET-EUROPE Service Activity is to operate this multi-site European infrastructure to provide calibration to european AERONET users.

The LOA installations for calibration are composed of indoor and outdoor platforms, located in Lille and Carpentras (France). The indoor platforms includea dark room for calibration relying on NASA-NIST traceable integrating spheres, polarized light sources, solar-simulator, maintenance and repair room, spectrometer for filters characterization, thermal chamber, and computers linked to AERONET/NASA database for calibration coefficients computation and data reprocessing. Two outdoor facilities were developped. The first outdoor plateform, located on the roof of LOA, is a special 100 m2 horizon-free platform, designed for functionnal tests (capacity: 10 sun photometers). Calibration transfer to field instruments relies on a complementary horizon-free outdoor platform located in the Carpentras Meteofrance center (100 m a.s.l) located in the South of France.
In 2010, LOA has a permanent capability to calibrate simultaneously 8 field instruments thanks to 2 reference instruments at the Carpentras site.

The Spanish installations comprise:

* GOA installation : it is composed of one outdoor horizon-free platform located at Autilla (870 m a.s.l.; 40 km from Valladolid university) enabling the calibration transfer simultaneously for 4 field instruments thanks 2 reference instruments. One indoor lab equiped with one integrating sphere plus a maintenance space at GOA. A computer is linked to AERONET/NASA database for calibration coefficients computation and data reprocessing. GOA received every 3 months a new set of 2 reference instruments calibrated at Izaña by LOA.

* Izaña platform (2400 m a.s.l) : this installation is composed of a set of 6 reference instruments continuously in operation and available for France and Spain needs on LOA and GOA installations. Such reference instrument has to be recalibrated every 3 months in order to preserve measurements accuracy. This site is similar to the one from NASA located in Hawaï at Mauna Loa Island.

Description of work

Modality of access under this project:
The typical sequence of calibration for annual calibration/maintenance is as follows: (1) reception of instrument sent by user in LOA or GOA; (2) post-field calibration-maintenance then pre-field calibration sequence; (3) final functionnal test in LOA or GOA; (4) inform user when instrument ready for shipping back; (5) calibration update in AERONET database; (6) request Quality Assurance analysis to GSFC/NASA. Continuity of observation during calibration phase can be requested to the AERONET-EUROPE service. The following user rights and duties apply:

1- Users will be given, once a year, access to calibration and standard cleaning / maintenance services.
Standard maintenance includes filters, polarizers and internal batteries changes for head and control box parts as well as microswitch and belt for robot. Once calibration achieved, quality assured data/products will be made available via the AERONET website.

2- The production of QA data also relies on the facts that users will have to
- perform weekly local maintenance of instrument following AERONET rules.
- reply promptly to send alarm regarding instruments problems detected by LOA & GOA
- manage shipping to the infrastructure and back.

Support offered under this project:
- Provide AERONET standard calibration services
- Reduce calibration time & increase length of observation period for user
- Reduce shipping time and custom’s issues thanks to availabilty of European calibration centers
- Provide unique polarization calibration facility

Outreach of new users:
The promotion of the AERONET-EUROPE Calibration TNA will be made through AERONET, LOA, GOA, Izaña and ACTRIS websites to provide timely, comprehensive information on the facilities and access opportunities. Network e-mailling list will be also considered.

Review procedure under this project:
-Distinction must be made between first time and reccurent user. Each AERONET user requesting, for the first time, calibration service will have to contact LOA. The selection of user will depend on a joint decision between LOA and GOA and will be based on several criteria such as, (i) prevent as much as possible geographical redundancy, (ii) favor user in region poorly or not yet covered, (iii) favor multi-instruments atmospheric stations.
-The choice of calibration installation (LOA or GOA) where the calibration will be performed is an internal decision mainly depending on (i) distance between calibration center and user’s site, (ii) instrument type, (iii) weather conditions, (iv) pre-existing scientific agreements.
-For recurrent calibration, within a 12-month period, the user will be automatically contacted by infrastructure staff to arrange the most suitable date for sending the instrument to the infrastructure.
-The calibration of reference instrument will be done at Izaña under the supervision of LOA.

Unit of Access:
The unit of access corresponds to the calibration and/or maintenance of one instrument per year per user.

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