The Copernicus Atmospheric Service (CAS), previously known as GAS (GMES Atmospheric Service), is to deliver policy-relevant services on atmospheric composition and climate. Quality assessment and quality control of the CAS data products and services are of key importance for ensuring the suitability of the CAS products for the atmospheric and climate change research communities, and for the adequacy of policy decisions. The satisfaction of the users and the competitiveness of the Service will depend strongly on the quality of the delivered data products. Therefore, this project aims at assessing and improving the quality of the CAS operational data products through the development and provision of customized high quality ground-based remote sensing data from the Network for the Detection of Atmospheric Composition Change (NDACC; This will be beneficial for all CAS applications beyond 2015.

In NORS, the required research and developments will be made to optimize the NDACC data and data products for the purpose of supporting the quality assessments of the future CAS.

The major objectives are

to implement procedures for operational data delivery of NDACC data to CAS actors with a delay of maximum 1 month;

to provide an extensive characterisation of targeted NDACC data and user documentation. The NDACC data will also be evaluated in comparison with satellite data that are assimilated in the CAS products, and against other network data like Global Atmosphere Watch (GAW) surface data and the Total Carbon Column Observing Network (TCCON) data, in a comprehensive and coordinated way;

to investigate the integration of ground-based data products from various sources (groundbased in-situ surface and remote-sensing data, and satellite data), and to provide the integrated data products to CAS. Hereto, new scientific methodologies will be developed.

to provide ground-based measurement time series back to 2003 in support of the reanalysis products of CAS. NORS will provide and archive quality-controlled long-term reference data sets for open access by CAS and Copernicus users, a need expressed in the CAS Implementation Group Final Report.

to develop and implement a new CAS-compliant web-based application for operational validation of CAS products using the NORS data products. In this validation service, better methodologies for validation will be included, based on the improved characterisation of the ground-based data. This service will be user-oriented.

to support the extension of NDACC to stations outside Western Europe, namely in the tropics, in China, Latin America, Africa and Eastern Europe.

NDACC is a cross-border international research network of remote sounding stations. It is a major contributor to the World Meteorological Organisation (WMO) GAW programme and it works under the auspices of United Nations Environment Programme (UNEP) and the International Ozone Commission (IO3C). Relying on a strong involvement of European partners and efficient collaboration with partners worldwide, the network started operations officially in 1991, but a few data records extend back to the 1970s and even to the 1950s. At present time it includes more than 70 high-quality, remote-sensing research stations/sites distributed worldwide for (i) observing and understanding the physical / chemical state of the stratosphere and troposphere, and (ii) assessing the impact of stratospheric changes on the underlying troposphere and on global climate.

Several NDACC priorities are directly relevant to the CAS:

  • Detecting trends in overall atmospheric composition and understanding their impacts on the stratosphere and troposphere,
  • Studying atmospheric composition variability at interannual and longer timescales,
  • Establishing links and feedbacks between climate change and atmospheric composition,
  • Calibrating and validating space-based measurements of the atmosphere,
  • Supporting process-focused scientific field campaigns, and
  • Testing and improving theoretical models of the atmosphere.

In NORS, we will focus on key species for the stratospheric ozone, air quality, and climate areas of CAS at 4 NDACC sites managed by European partners, as a demonstrator, with the objective of exporting the achievements of NORS to many stations of the global NDACC network and to additional species in the near-future.

The species actually focused on in NORS are

  • tropospheric and stratospheric ozone columns and vertical profiles up to 70 km altitude;
  • tropospheric and stratospheric NO2 columns and profiles;
  • lower tropospheric profiles of NO2, H2CO, aerosol extinction;
  • tropospheric and stratospheric columns of CO
  • tropospheric and stratospheric columns of CH4

They are listed in the CAS Implementation Group Final Report as priority species for the above mentioned areas, and they are products of the current MACC (Monitoring Atmospheric Composition and Climate Interim Implementation) services.
Within NORS they will be monitored using standard NDACC remote-sensing techniques, based on Fourier Transform InfraRed (FTIR) and MicroWave (MW) spectroscopy, UV-Visible Differential Optical Absorption Spectroscopy (DOAS) and multi-axis DOAS or MAXDOAS, Microwave spectroscopy and differential absorption lidar technique. This selection of instruments represents all NDACC type of instruments that are suited to monitor the above species, with the exception of Dobson/Brewer instruments and ozone sondes of which the data are already included in the validation activities for CAS. The sites included in NORS for operational data delivery to CAS are NyÅlesund in the Arctic (79°N, 12°E), the Alpine station including the International Scientific Station of the Jungfraujoch (47°N, 8°E), Bern (47°N, 7°E) and the Observatoire de Haute Provence (44°N, 6°E), Izana (28°N, 16°W) in Tenerife at low northern latitudes, and Ile de La Réunion (21°S, 55°E) in the southern hemisphere tropics.

Hereinafter, the above products will be called the target NORS data products and the sites will be referred to as the 4 NDACC pilot stations.

Regarding the web-based validation services, it will be investigated how the NORS validation service can be integrated in existing systems or systems under development in support of the CAS. Developed in response to the GEO Tasks DA-06-02/DA-09-01 that address a GEOSS data quality strategy for Earth Observation data and higher level data products, the ESA Generic Environment for Calibration/Validation Analysis (GECA) is a natural candidate. This system will already provide a server for consistent validation of European satellite sensors using ground-based data and it is our intention in NORS to extend its capabilities to include a validation service for CAS. Therefore, the NORS Steering Committee will include an ESA representative for GECA. The collaboration with the Copernicus Atmospheric Core Service project and the use of the GECA system will ensure access to the satellite data needed in the NORS project.

The project will be carried out in close collaboration with other actors in Copernicus, previously known as GMES (Global Monitoring for Environment and Security): leading members of relevant Copernicus Atmospheric Service projects will be invited to be member of the NORS Steering Committee. The Project Management Team will liaise with the European Environmental Agency (EEA) who is responsible for the coordination of the in-situ data for Copernicus; an EEA representative will be member of the NORS Steering Committee. It will also promote the NORS activities in the NDACC community: the NDACC co-chairman will be a member of the NORS Steering Committee and several members of the NORS consortium have steering roles in NDACC as co-chairmen of working groups and as members of the NDACC Steering Committee. The idea behind this is to gradually achieve an enlarged and sustained involvement of NDACC partners in the CAS products chain. The project will also liaise with upstream satellite partners of CAS, namely, the community of operational satellite data providers, represented in the NORS Steering Committee by a member of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration and Validation (WGCV).

NORS will be addressing several points that, according to the CAS Implementation Group Final Report, should be in the focus of EU funding for CAS: (i) the European contribution, in particular through European capacities, to international observation networks and data management systems, (ii) technical coordination activities like cal/val and data management facilities, and (iii) gap filling in observation infrastructure in eastern Europe and outside Europe.