Objectif
Theoretical studies have indicated that, especially during summer, two-way exchange across the midlatitude tropopause can occur relatively freely. This is supported by a limited number of aircraft measurements (e.g. by this group), indicating that polluted tropospheric air can be mixed into the lowermost stratosphere. This can have important implications for ozone trends and aircraft emissions in this part of the atmosphere.
The first objective of the proposed project is to investigate the effects of stratosphere-troposphere exchanges on the chemical composition of the lowemmost stratosphere in northem mid-latitudes.
Particular emphasis is given to the budget of reactive nitrogen species (NOy). The research will be performed on the basis of aircraft measurements over Canada, the North-Atlantic Ocean and westem Europe, during the summer of 1998. The measurements will provide a basis for modelling studies.
The project involves deployment of a high flying twinjet aircraft (70 flight hours) to measure nitrogen oxides, ozone, water vapor, aerosols, sulphur species, carbon monoxide, hydrocarbons and many other gases to quantify the chemistry and dynarnical history of air parcels in the lowemmost stratosphere. These studies will be supported by high resolution ECMWF meteorological analyses, back-trajectory calculations and associated chemistry modelling.
The measurements will guide 3-D chemistry-transport and radiative transfer simulations to simulate the consequences of anthropogenic perturbations. In particular, we will assess the importance of cross-tropopause exchanges of trace species relative to aircraft emissions in the lowemmost stratosphere.
In addition to these pollution studies we plan to investigate the sulphur budget of the unperturbed lower stratosphere. This will be particularly interesting if no major volcanic eruptions reach the stratosphere before our campaign in the summer of 1998. The measurements will quantify the relationship between carbonyl sulphide and sulphate and provide a much needed basis for model calculations of the stratospheric sulphur cycle.
The project will reinforce the collaborative efforts of 9 European research groups and a Canadian group that have collaborated successfully in the past. This proposal requests support for a 2 year project that includes a 40 flight hour measurement campaign, and the salaries of 1.5 technical staff, 8 Ph.D students and post-docs to prepare and participate in the measurements, data analysis and their interpretation. The Canadian part of the campaign (30 flight hours) and scientific contributions by York University, will be supported through Canadian resources.
Champ scientifique
- natural sciencescomputer and information sciencesdata science
- natural scienceschemical sciencesinorganic chemistryinorganic compounds
- engineering and technologymechanical engineeringvehicle engineeringaerospace engineeringaircraft
- natural scienceschemical sciencesorganic chemistryhydrocarbons
- natural sciencesearth and related environmental sciencesatmospheric sciencesmeteorologytroposphere
Appel à propositions
Data not availableRégime de financement
CSC - Cost-sharing contractsCoordinateur
3584 CC UTRECHT
Pays-Bas