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VINTERSOL – A New European Field Campaign

N.R.P. Harris , EORCU, University of Cambridge, UK (Neil.Harris@ozone-sec.ch.cam.ac.uk)
G.T. Amanatidis, European Commission, DG Research, Belgium (georgios.amanatidis@cec.eu.int)

 

VINTERSOL (Validation of INTERnational Satellites and study of Ozone Loss) is a major European field campaign studying stratospheric ozone. VINTERSOL (‘Winter sun’ in the Scandinavian languages) is taking place from late 2002 until mid 2004. There have been three previous European campaigns: the European Arctic Stratospheric Ozone Experiment (EASOE) in 1991/92; the Second European Stratospheric Arctic and Mid-latitude Experiment (SESAME) in 1994/95; and the Third European Stratospheric Experiment on Ozone (THESEO) in 1998/2000. Like them, VINTERSOL relies on support from national funding agencies and from the Environment and Sustainable Development programme of EC DG Research. More information on VINTERSOL, including the full planning document, can be found at http://www.ozone-sec.ch.cam.ac.uk/

There are four main scientific themes within VINTERSOL:

These are being addressed in the three main phases:

In addition, a number of measurement and modelling projects are running continuously through this period yielding information on the longer time-scale processes in the stratosphere, and there is a small balloon campaign in the tropics in early 2003 in preparation for the main tropical phase.

An important dimension for VINTERSOL is the involvement of several new European satellite instruments. Measurements from the ERS-2 GOME satellite instrument (operational since 1995) and from the POAM III instrument on the SPOT IV satellite (operational since 1998) continue to be used. The ODIN satellite (launched in February 2001) and ESA’s Envisat satellite (launched in March 2002) data are being validated and analysed.

The international dimension to earth observation studies is increasingly evident. There is close collaboration between VINTERSOL and field campaigns primarily associated with satellite validation. Close links, including joint flight planning and data sharing, have been forged with the NASA SAGE III Ozone Loss and Validation Experiment II (SOLVE II, see http://cloud1.arc.nasa.gov/solveII/index.html) based on the successful cooperation in SOLVE THESEO 2000 in the 1999/2000 winter. Cooperation has also been agreed with the Envisat validation activities (http://envisat.esa.int) organised by the ESA and national space agencies through the Atmospheric Chemistry and Validation Team (ACVT) and particularly its Envisat Stratospheric Aircraft and Balloon Campaigns (ESABC). All three field campaigns have extensive field activities in Kiruna, Sweden (68°N) during the 2002/03 winter. The joint initiative involves over 400 scientists from the European Union, Canada, Iceland, Japan, Norway, Poland, Russia, Switzerland and the United States. Aircraft, large and small balloons, ground-based instruments and satellites are being used to measure ozone and other atmospheric gases and particles. The combined activities thus aim to improve understanding of Arctic ozone depletion, and at upgrading satellite observation of the ozone layer. In addition, VINTERSOL significantly extends the scope and duration of the other planned satellite validation activities.

Arctic Ozone – November 2002 to March 2003

An improved understanding of polar ozone loss is one of the major aims of VINTERSOL. A great deal has been learnt in recent years, particularly during SOLVE-THESEO 2000, but there are a number of outstanding issues which restrict our ability to understand the processes leading to polar ozone loss and to predict future ozone losses with confidence. Many of these (vortex dynamics; particle composition; denitrification; heterogeneous processes; the photochemical reactions depleting ozone; empirically determined and modelled ozone losses; and the relation between Arctic and Antarctic ozone loss) are addressed directly in VINTERSOL

The 2002/03 Arctic phase will involve several aspects:

The M55 Geophysica and the DLR Falcon are based in Kiruna during January and February 2003 in the EC EUPLEX project. The Falcon with a remote-sensing payload acts as a pathfinder for the Geophysica (with primarily an in situ payload) directing it, for example, into synoptic and lee-wave PSCs. The Geophysica is also studying the chemical evolution in individual air parcels by measuring in them twice a few days apart. Trajectory calculations based on analysed and forecast winds from ECMWF are triggered along all flight tracks. If the air masses return to within the aircraft range, e.g. after they circled the polar vortex once, they can be probed again. The NASA DC-8 is based in Kiruna in January and early February, and is closely coordinated with the Geophysica and Falcon. In March, the Geophysica and Falcon are involved in Envisat validation with the Geophysica based in Kiruna and the Falcon covering a wide range of latitudes from the pole to the equator.

Three successful balloon flights took place in early December 2002 within the CIPA/POSTA projects. Two flights of the PSC Analysis gondola and one of the MIPAS-B instrument were made from Esrange in synoptic scale PSCs. The PSC Analysis payload carried instruments for comprehensive in situ measurements of chemical and physical properties of PSC particles. The MIPAS instrument flew simultaneously with the second PSC Analysis flight to study the interaction between HNO3 gas phase abundance and PSC formation, while the DLR Falcon aircraft performed upwind and downwind flights to observe the larger scale properties of the PSCs. In addition to these VINTERSOL flights, there are two flights of the NASA OMS remote balloon payload within SOLVE II and 11 flights for a variety of European payloads in ESABC, four in late January and seven in March.

An Arctic Match campaign involving about 500 ozonesondes and 13 stations is organised within the QUOBI project. Air parcels in which ozone has been measured are tracked and, if these air parcels are likely to pass over another station, launch requests are issued to the stations. While the main aim is to provide accurate estimates of ozone loss rates for comparison with stratospheric models, two periods of special interest have been identified. First, with the vortex cold in November/December 2002, a Match campaign is being run to study ozone loss in cold dark conditions. Second, special attention is being paid to making good estimates of the ozone loss as this is the period where there are significant disagreements with photochemical models. The Match ozone loss studies are complemented by other approaches using ozonesonde, satellite and ground-based data.

Ground-based observations in the northern hemisphere are being made throughout the 2002/2003 Arctic winter, using instruments measuring stratospheric composition (UV-vis, FTIR, lidars and microwave instruments which are principally from NDSC and NDSC-related sites), total ozone in the WMO GO3OS, and UV radiation in the European UV network. These are involved in the EU projects EDUCE, QUILT and UFTIR. In addition, the lidar at Esrange is operational for several weeks in January and February 2003. The NDSC comparison of UV-vis instruments takes place between mid-February and mid-March 2003.

Measurements from satellites such as GOME, POAM III and ODIN are used for studies of the 2002/2003 Arctic winter. With the ODIN satellite, atmospheric measurements (ClO, HNO3, OClO and BrO) are made normally about one day in three. However arrangements have been made for additional 15 days of atmospheric observations in early 2003. Further with a few days warning, it is possible to change the observational schedule so that extended periods of observations can be made in periods of special interest. Envisat measurements are not routinely available for scientific use until after the commissioning and validation phase. However the available data are being used in chemical data assimilation models to produce synoptic maps of several key species and in cloud detection schemes to identify PSCs and cirrus. In addition, GOME data are being assimilated to provide ozone fields. SAGE III data are also available in near real-time.

A range of models are being run in the 2002/03 winter within the MAPSCORE, QUOBI and TOPOZ III projects. SLIMCAT and REPROBUS are run throughout the winter with full 3-D chemical fields available within a few days, and other 3D CTMs will be run with longer delays. Detailed models of PSC microphysics and chemistry are used to interpret the aircraft measurements and the PSC Analysis, MIPAS and other balloons. Any widespread denitrification of the vortex is being studied with composite model approaches linking microphysical models, pseudo-Lagrangian trajectories including sedimentation, and 3D chemical transport models. Photochemical Lagrangian models are used to study detailed chemical evolution, for example the results of any aircraft Match flights and the ozone losses from the Match ozonesonde campaign.

Antarctic Ozone – June to October 2003

The first ever Antarctic Match campaign will be run between June and October 2003 within the QUOBI project. It will be the most comprehensive analysis of ozone loss rates in the Antarctic ozone hole. Nine stations will be involved in the Match campaign with the participation of the Antarctic research programmes from 8 countries (Argentina, Australia, Finland, France, Germany, Japan, Spain, UK and USA). A total of nearly 600 ozonesondes will be launched between 65° and 90°S (4-5 ozonesondes per day inside the vortex). Approximately 400 additional radiosondes will be launched to improve the quality of the meteorological analyses provided by ECMWF. This will improve the quality of the ozone loss estimates derived by Match and other empirical ozone loss techniques. In addition, it will have the benefit of assisting the meteorological agencies in understanding the factors which limit the quality of their forecasts in this data-sparse part of the world.

The Match campaign will be supplemented by satellite studies, ground-based measurements and modelling. In particular, this will be the first winter at either pole where Envisat measurements are made operationally, so the chemical and particle fields will be well characterised. This means allow detailed, well-constrained studies of the observed ozone loss rates can be made. The experience gained in the Antarctic should significantly improve our understanding of the processes occurring in the Arctic

Tropical phase – January to March 2004

The source of chemical species involved in stratospheric ozone depletion at global scale lies in the tropics where they are transported vertically from surface level to the tropopause by deep convection. This vertical transport can take place either gradually as part of the general atmospheric circulation or rapidly in convective storm systems. A number of issues related to the tropical UT/LS which are important for ozone and climate in the future are:

These issues are important in order to assess the chemical impact on the UTLS of biomass burning, changes of agricultural practices and pollution from the fast growing populations in tropical developing countries. In addition the transport of air out of the tropical UTLS into mid-latitudes is one of the critical factors which determine the composition of air in the mid-latitude lower stratosphere.

The main sub-tropical phase will involve balloons and aircraft campaigns in the HIBISCUS and TROCCINOX projects. It will take place in January and February 2004 in Sao Paolo State in Brazil. Small balloon and long duration MIR balloon flights will be launched from Bauru and the M55 Geophysica and the DLR Falcon will be deployed nearby. Ozonesondes and additional radiosondes will be launched in the region of Bauru, and there will be access to the measurements made by the lightning network and 2.6 GHz radar. In addition, coordinated measurements will be made from the ground station at La Réunion and full use will be made of in service commercial aircraft measurements within the MOZAIC and CARIBIC projects. Global fields of many chemical constituents in the UTLS will be provided by satellite instruments such as those on Envisat and ODIN. These plans can be modified in the light of the preliminary phase in February 2003. A scientific workshop will take place from 15-17 May 2003 at DLR Oberpfaffenhofen.

This article was written on behalf of the VINTERSOL core group (other members G.O. Braathen, NILU, Norway; M.P. Chipperfield, Univ. Leeds, UK; H. Kelder, KNMI, Netherlands; N. Larsen, DMI, Denmark; M.De Mazière, BIRA-IASB, Belgium; G. Mégie, CNRS, France; D. Murtagh, Chalmers Univ., Sweden; J-P. Pommereau, CNRS-SA, France; J. Remedios, Univ. Leicester, UK; H. Schlager, DLR, Germany; L. Stefanutti, CNR, Italy; F. Stroh, FZ Jülich, Germany; P. Taalas, FMI , Finland; and P. von der Gathen, AWI-Potsdam, Germany).

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