Upper troposphere and lower stratosphere in global change: concerted European research action (COST)

March 19, 2002

Brussels, 18 March 2002

European Cooperation in the field of Scientific and Technical Research - COST Secretariat. Memorandum of Understanding for the implementation of a concerted European research action designated as COST Action 723 "The Role of the Upper Troposphere and Lower Stratosphere in Global Change." Brussels, 15 March 2002 (document COST 226/02). Full text

Delegations will find attached hereto the text of the abovementioned Memorandum, signed in Brussels on 6 March 2002 by Denmark, Germany and Greece, on 11 March 2002 by Poland and on 13 March 2002 by the United Kingdom.

The Signatories to this Memorandum of Understanding, declaring their common intention to participate in the concerted Action referred to above and described in the Technical Annex to the Memorandum, have reached the following understanding:

1. The Action will be carried out in accordance with the provisions of document COST 400/01 `Rules and Procedures for Implementing COST Actions', the contents of which the Signatories are fully aware of.

2. The main objective of the Action is to advance the understanding of the state of the global upper troposphere and lower stratosphere, and the role of the dynamical, chemical, and radiative processes in this altitude region, in order to provide an improved basis for policy advice in connection with global change.

3. The economic dimension of the activities carried out under the Action has been estimated, on the basis of information available during the planning of the Action, at EURO 7 million in 2001 prices.

4. The Memorandum of Understanding will take effect on being signed by at least five Signatories.

5. The Memorandum of Understanding will remain in force for a period of four years, unless the duration of the Action is modified according to the provisions of Chapter 6 of the document referred to in Point 1 above.


This COST Action deals with the global upper troposphere and lower stratosphere (UTLS), the region approximately 5 kilometres above and below the tropopause. This altitude region of the Earth's atmosphere plays an important role in the Earth's climate and in possible climate change.

The upper troposphere, lower stratosphere region (UTLS) is crucial for the Earth's energy balance, as changes in the composition of the UTLS, notably the water vapour and ozone distributions, have a direct impact on the amount of radiation absorbed and emitted. Water vapour is the main source of cooling in the upper troposphere, whereas ozone is the main source of warming in the lower stratosphere. Thus, changes in UTLS water vapour and ozone can change the temperature structure of the atmosphere, and hence atmospheric transport and cloud formation. This constitutes a complex feedback mechanism, as subsequent changes in UTLS temperature and transport exert a controlling influence on the ozone and water vapour distributions in the UTLS region.

An understanding of the UTLS region requires knowledge of composition, radiation, dynamics, transport, photochemistry, and cloud microphysics; knowledge of the climatology, variability, and long-term trends in the UTLS region; knowledge of the interactions between the troposphere and stratosphere, and between the tropics and extra-tropics. Current concerns about climate change and ozone depletion have also highlighted the need to have the ability to simulate and predict both natural and anthropogenically induced variability in the UTLS region.

The climate system and the UTLS region in particular, have several strong feedback mechanisms involving water vapour, ozone and clouds. These mechanisms involve radiative, photochemical, dynamical, transport, and microphysical processes. Despite their importance, the composition and processes in the UTLS region are not well understood. There is both a lack of data, and a lack of models, which resolve the crucial processes.

Currently, global remote sensing methods from operational or research satellite platforms are unable to make accurate height-resolved measurements in the UTLS region. In situ measurements in the UTLS region suffer from a lack of global coverage. To capture the behaviour of the UTLS region, processes such as cloud formation and chemistry on cloud particle surfaces must be modelled. Such processes are notoriously difficult to model because of the need for parameterisations in large-scale numerical models, and a lack of understanding of many of the crucial microphysical and photochemical processes.

The monitoring of the UTLS region requires an appreciation of the strengths and weaknesses of the various measurement techniques. It also requires the use of data assimilation techniques to confront observations and models, and combine them if they are consistent, thus adding value to the observations and evaluating both the observations and the models.

Modelling developments such as the coupling of climate and chemistry models, and observations from ESA's forthcoming Envisat satellite (as well as NASA's forthcoming EOS Aura satellite) will play an important role in our understanding of the UTLS region and will be a focus of this COST Action.

Understanding and monitoring the UTLS region requires a coordinated, broad-based and multi-disciplinary approach, which brings together the world-class expertise available in Europe. Key elements of this task are: (1) the optimum use of scarce Earth Observation and modelling resources which builds upon existing resources and avoids duplication of effort, (2) the exchange of ideas and information in order to advance understanding, and (3) the development of links (including electronic networks) for European and world-wide collaboration. The Action incorporates all of these key elements. Thus, it is a good tool to achieve the sustained multi-disciplinary effort that is necessary to provide policy makers with the information needed to make decisions in response to perceived environmental threats.

The COST Action can contribute to the European-wide training of scientists, the exploitation of Europe's world-class skills in Earth Observation and modelling, a European policy for Earth Observation and climate monitoring, and the concept of a European Research Area. Thus, the COST Action can help to provide the healthy and attractive research environment in Europe needed to retain the best scientists from Europe and elsewhere. The European Commission (EC) has identified all these issues as being highly desirable. In consonance with the goals of the European Research Area concept, the COST Action brings together several important European activities in the area of Earth Observation, modelling and data assimilation. These activities are described in Section D-4....

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