WP 1: Chemistry
Leaders: F. Stroh, C. Camy-Peret
Stratospheric ozone which itself is partly dominated by chemistry is governing the radiative budget of the stratosphere and therefore is a key species in stratosphere-climate interactions. The need to integrate stratospheric processes controlling ozone into future climate models was recently identified by Baldwin et al., (Science, 2007). In order to reliably simulate the atmospheric ozone abundance varying in space and time within models all relevant processes have to be fully understood. Generally, the picture seems to be solid in terms of chemical reactions, however, the reaction rates of major chemical processes controlling stratospheric ozone are still under discussion. We propose to study the relevant processes in late winter and early spring inside as well as outside the polar vortex through balloon-borne measurements of four well-proven payloads.
The main objectives are:
- Characterization of the chemical state of the lower stratosphere in late winter and early spring conditions in- and outside of the arctic polar vortex.
-
Comprehensive investigation of the partitioning and photochemistry especially of chemical
species within the:
- Chlorine
- Bromine
- Nitrogen oxide chemical families
- Evaluation of the consistency of the ClOx chemistry and partitioning with laboratory results and numerical models
- Continuation of the bromine trend taking into account age of air issues and the photolysis rate of BrONO2.
- Evaluation of the rate of stratospheric nitrogen redistribution (de-/renitrification) and the associated processes
This proposal is thematically linked to the EU funded RECONCILE project. Within RECONCILE an airborne measurement campaign was conducted in winter 2009/2010 in the Arctic in order to improve the understanding of processes like ClOx partitioning, NOy redistribution, PSC formation, dynamical processes, and chemical ozone depletion (von Hobe, EGU Conf., 2010). We propose to extend the relevant research to the altitude regime above 20 km that can not be readily probed from high-flying aircraft but is crucial for chlorine activation, denitrification and ozone loss.
A. Chlorine chemistry
Questions we will try to answer- Is the partitioning within the Cly family in the altitude range 10-30 km consistent with current laboratory data and numerical models?
- How does the equilibrium between ClO and its dimer ClOOCl behave over the respective altitude regime?
- What are the consequences for the speed of the ClO dimer catalytic ozone destruction cycle?
B. Bromine chemistry
Questions we will try to answer- How does inorganic bromine, Bry evolve in the arctic stratosphere? Is there a stabilization?
- Is the Bry partitioning taking into account new measurements of BrONO2 consistent with the current understanding of BrONO2 photolysis?
- How well is our understanding of OClO formation and the speed of the ClO-BrO catalytic ozone loss cycle reproducing amospheric measurements ?
C. Nitrogen oxides chemistry
Questions we will try to answer- Probe the chemical and microphysical conditions of NOy redistribution in the Arctic vortex from the tropopause to ~32 km and compare to model scenarios.
- Determine the chemical partitioning in the complete NOy family and their linkages to the chlorine and bromine families over the complete lower arctic vortex and compare to models.
- Identify the origin of the NOx species (N2O dissociation, mesospheric or thermospheric descent), based on its source N2O and on mesospheric tracers (CH4, CO)
- Determine the relationship between density of surface per unit of volume for aerosols (used in the models) and size distribution (what is measured).
Link to the description of the other workpackages.
-
WP 2: Dynamics
- Leaders: N. Huret, A. Engel
-
WP 3: Cross comparison
- Leaders: V. Catoire, M. Dorf
-
WP 4: Satellite Validation
- Leaders: H. Oelhaf, S. Payan
