3 – 15 October 2005



Satellite instruments, in-situ and remote measurements of water vapour and chemical compounds, clouds in the UT/LS, data evaluation.

Data assimilation

Theory, assimilation of satellite data, numerical weather prediction, assimilation in global models of atmospheric chemistry

Modelling and understanding

Dynamics and global circulation, transport and mixing, ozone chemistry, cirrus clouds, water budget in the UT/LS, tropical dehydration


M. Baldwin (NWRA), F. Bouttier (MétéoFrance) , S. Buehler (Univ. Bremen), J.-P. Cammas (Univ. Toulouse), B. Carli (CNR/IFAC), D. Fonteyn (BIRA/IASB), A. Gettelman (NCAR), K. Gierens (DLR), A. Heymsfield (NCAR), H. Kelder (KNMI), W. Lahoz (Univ. Reading), B. Legras (LMD/IPSL), P. Levelt (KNMI), L. Moyer (Harvard Univ.), A. O'Neill (Univ. Reading), R. Swinbank (Met. Office), O. Talagrand (LMD/IPSL), G. Vaughan (Univ. Manchester), H. Wernli (Univ. Mainz)


A key region for meteorology and climate is the atmospheric layer made of the upper part of the troposphere and the lower stratosphere (UTLS). The chemical composition of this layer has a strong impact on the global ozone budget and therefore on the radiative balance of the Earth. Part of the changes of chemical composition (e.g. O3, CH4, CO and carbonated aerosols) observed in the UTLS can be directly traced to anthropogenic effects, like the injection of pollution by convection or the release of pollutants by air traffic. Other changes, like the increase of water vapour in the stratosphere and the decrease of temperature at the tropopause are probably part of a more general climate trend. The mechanisms underlying these changes are still poorly understood.

Outstanding issues concerning the UTLS region include: aerosols and their role in climate, stratosphere-troposphere coupling, feedbacks between water vapour and clouds, distribution and variability of lower stratosphere ozone and water vapour, and the role of tropospheric ozone and chemically active greenhouse gases.

Studies on the UTLS region have received a large impetus over recent years from dedicated research programs, notably those supported by the FP5 and FP6 programs of the EU. Furthermore, and after a gap of several years following the very successful NASA UARS project, there is a wealth of satellite data, either from missions in orbit or from missions due to be launched soon (e.g. ODIN, ENVISAT, EOS AURA). All these satellites carry instruments sounding the UTLS and provide measurements of key chemical species (e.g. water vapour, ozone and NOy). Several measurement campaigns are also planned over the next few years, particularly in the tropics (e.g. SCOUT-O3, AMMA, TC4).

A new development in the studies of the UTLS is the increased use by many research groups of assimilation methods to confront observations with advanced modelling tools. The resulting quality-controlled datasets are a key tool for understanding the role of the UTLS in climate.

The goal of the school is to present an integrated overview of the physical, chemical and dynamical processes in the UTLS as provided by observations, data assimilation and modelling.

The lecture courses will be complemented by computer practice, sessions of questions and anwers, theme discussions and poster presentations. The course is aimed primarely at PhD students, postdocs and other young scientists wishing to broaden and deepen their knowledge or to identify new research opportunities.

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