Research project CG/DD1/01 (Research action CG)
Context
The Earth's atmosphere is changing. Beside natural variations, important anthropogenic influences have been recognised. The quantification and understanding of these changes are among the objectives of ESAC.
Objectives
ESAC aims at assessing atmospheric changes, in particular the stratospheric composition including the ozone layer and ozone depleting constituents, tropospheric pollution effects, and the related changing UV irradiance at the Earth surface. The various temporal and spatial scales of the changes must be discerned. The goal is to provide scientific criteria upon which regulations to preserve the Earth atmosphere and environment can be based.
ESAC warrants the continuity of the Belgian contributions to international programmes like NDSC and WCRP (World Climate Research Program), and to the development of new or improved detection techniques and study approaches.
Methodologies
The methodology adopted in ESAC is based primarily on experimental observations, coupled to numerical modelling methods.
The observations are done with remote sensing methods based on optical spectrometry in the UV-visible (Differential Optical Absorption Spectroscopy, or DOAS) and infrared (Fourier Transform Infra-Red, or FTIR) spectral ranges, and on spectral UV radiometry. In situ ozone soundings are performed regularly at Ukkel. The instruments are operated on a quasi-continuous basis at four stations in Europe of which the former three are part of the NDSC: Harestua (Norway), Jungfraujoch (Switzerland), OHP (France), and Ukkel (Belgium). The obtained time series are complemented with data from campaign measurements at chosen sites, and with data from space experiments, in particular from ATMOS on the Space Shuttle. At the same time, they serve efforts for validation of atmospheric models and of space-based measurements.
Advanced numerical models are exploited to support the interpretation of the data sets.
Laboratory measurements of spectroscopic parameters of gases of atmospheric relevance are performed to improve the retrieval results of the observed atmospheric spectra.
Partners
ESAC counts 4 partners, complementing each other :
The Royal Meteorological Institute of Belgium (KMI-IRM), the Institut d’Astrophysique et Géophysique of the University of Liège (ULg), the Laboratoire de Chimie Physiqe Moléculaire of the Université Libre de Bruxelles (ULB), and the Belgian Institute for Space Aeronomy (BIRA-IASB) which coordinates the project.
They share the responsibilities regarding observations and data analysis.
BIRA-IASB, ULg, and KMI-IRM contribute to validation activities of space-based measurements, ozone in particular, and ULB and BIRA-IASB are in charge of the laboratory measurements.
Particular foci and methodologies of each partner are
1.For KMI-IRM:
- Determination of ozone trends and their origin over Belgium, and studies of ozone exchange between the atmospheric boundary layer and the free troposphere. Hereto, long time series of ozone, UV-B and relevant meteorological parameters are used. These time series come from regular balloon soundings and measurements with spectrophotometers, after homogenisation.
- Forecasts of the ozone abundance and of the UV-B index, by means of a radiation model; quality checks are provided by daily UV-B observations.
2. For ULg:
- Assessments of variabilities and trends of many stratospheric and tropospheric species and of some greenhouse gases above the Jungfraujoch. The time series start in 1985.
- Development of FTIR operational techniques.
- Contribution to the ATMOS experiment: data retrieval and validation.
3. For BIRA-IASB:
- Validation of ground-based ozone and NO2 measurements.
- Improvements to the DOAS technique and instrument developments.
- Developments as to FTIR retrieval algorithms.
- Detection of the variations of ozone, NO2, OClO and BrO at the three NDSC sites involved.
- Modelling support.
4. For ULB and BIRA-IASB:
- Laboratory spectroscopy with high resolution Fourier transform spectrometers (FTS).
- Theoretical studies concerning the Earth radiative balance.
- Studies of boundary layer pollution events in Brussels, by long-path DOAS measurements.
- Campaign measurements with mobile instruments.
Deliverables and expected results
- UV index forecasts, that are distributed through the media ; their meaning is explained to the public in a folder.
- Improved measurement techniques (instruments, algorithms,) and characterisation of instruments in use.
- Archives of validated databases of abundances of atmospheric constituents.
- Homogenised long time series of ozone (total amount and vertical distribution) and UV-B.
- Spectroscopic data in support of atmospheric studies.
- Trend analyses of various atmospheric constituents, in particular of ozone and its tropospheric budget.
- Process analyses, e.g., within THESEO, tropospheric campaign at ISSJ.
- Contribution to satellite validation, in particular ATMOS, HALOE/UARS, TOMS.
- Contributions to International Assessments (e.g., SPARC assessment of trends in the vertical distribution of O3, WMO/UNEP Assessment of O3 depletion) which are at the basis of regulations like the Montreal and Kyoto protocols, and of decisions by policy makers.
Scientific collaboration
- NDSC partners, including experimental and modelling groups.
- Memberships of the NDSC and SPARC Steering Committees.
- Partners in EC projects and campaigns, like COSE, SUVDAMA, PAUR, COST 713, RIFTOZ, TOR-2 (EUROTRAC-2), SCUVS-3, THESEO, ‘Ozone destruction by stratospheric bromine’; membership of the European Ozone Research Co-ordinating Unit - THESEO Core group.
- Membership of the Ozone SAF (Satellite Application Facility) of EUMETSAT.
- ATMOS-related : JPL, Caltech, Harvard, LaRC, GSFC, NCAR, U. Denver, U. Alabama, AER,...
- Satellite teams (ATMOS, HALOE, CLAES, MOPITT, TOMS, CRISTA, the ENVISAT Atmospheric Chemistry Validation Team,...).
- Solvay, many universities in Europe (e.g., UCL, Groupe de Spectrométrie Moléculaire at Atmosphérique of Univ. Reims, CNRS-SA and Univ. Paris VI), and the Univ. of Waterloo (Canada), for collaborations on laboratory spectroscopy data, and on the degradation and radiative forcing of HFC-365mfc.
Experimental studies of Atmospheric changes (ESAC): final report
De Mazière, M. - Colin, R. - De Muer, D. ... et al Brussels: OSTC, 2001 (SP0921)
[To download]
[Exhausted]
Experimental studies of atmospheric changes (ESAC): summary
Brussels: OSTC, 2001 (SP0991)
[To download]
Experimentele studies van veranderingen in de atmosfeer (ESAC): synthese
Brussel: DWTC, 2001 (SP0992)
[To download]
Etudes expérimentales de changements atmosphériques (ESAC): synthèse
Bruxelles: SSTC, 2001 (SP0993)
[To download]
