StraPolEte : Workpackages

Strategy
The core of the project is based on measurements obtained during an Arctic campaign involving six flights of balloon-borne instruments in August 2009. The project is divided into 6 workpackages (WPs). The first one is dedicated to the preparation of the campaign, the finalization of some instrumental developments and flight coordination during the campaign. Highly sensitive measurements will be provided and will serve the scientific objectives divided into four scientific WPs. For each WP, additional measurements from instruments onboard satellite platforms will be used and systematic comparison will help for data interpretation. The data set obtained from balloon-borne instruments and satellites will allow us to provide a detailed picture of the polar stratosphere in August. Concerning the modeling approach the goal is twofold with firstly an assessment of their operational results from comparisons with measurements and secondly detailed investigations to highlight key processes controlling the stratosphere composition and to improve the model calculations.
The five scientific WPs are :

Campaign
    Coordinators: V. Catoire and G. Berthet (Partner 1)
Dynamical investigations
    Coordinators: N. Huret and F. Lefèvre (Partner 1 and 4)
Stratospheric aerosol characterization
    Coordinator: J.-B. Renard (Partner 1)
Bromine budget investigations
    Coordinator: G. Berthet (Partner 1)
Reference state determination before the settling of the winter polar conditions
  Coordinator: S. Payan (Partner 2)

Measurements and data set

Data set used come from measurements obtained during the campaign (August 2009) by balloon borne instruments and by satellite plateform since the vortex breakdown ( March 2009) to autumn (2009) September 2009

Instrument	Measurement technique	Measurements used	Retrieval altitudes provided & vertical resolution
SPIRALE (Partner 1)	In situ Direct Infra-red absorption	O3, CH4, N2O, HCl, CO, HNO3, NO2, OCS	10km-35km 5m
IASI-Balloon (Partner 2)	Remote sensing Infra-red, nadir and limb	CO, CH4, CO2, OCS	Partial columns
LPMA (Partner 2)	Remote sensing Infra-red solar Occultation	O3, HNO3, NO, NO2, CH4, N2O, HCl	15km-35km 1km
DOAS (Partner 2)	Remote sensing UV Solar occultation	BrO	15km-35km 1km
SALOMON-N2 (Partner 1)	Remote sensing UV-visible solar pointing	O3, NO2, BrO, aerosol extinction	15km-35km 1 km
STAC (Partner 1)	In situ aerosol counter	Size distribution of aerosols	10km-35km 10m
MicroRADIBAL (Partner 3)	Remote sensing Scattering and polarization by photopolarimetry	Nature (liquid, solid), size distribution of aerosols	15km-35km 1km

Instrument	Measurement technique	Measurements used	Approximate retrieval altitudes provided & Vertical resolution
GOMOS (ENVISAT satellite)	Stellar occultation UV-visible and near-Infra-red	O3, NO2, aerosol extinction	18km-40km 2-3km
MIPAS (ENVISAT satellite)	Infra-Red atmospheric emission	O3, N2O, CH4,CO , NO2, HNO3, N2O5	18km-40km 3km
IASI (MetOp satellite)	Infra-Red Nadir pointing	O3, CO, CH4, N2O, O3	Column and partial column
MLS (EOS Aura satellite)	Microwaves	H2O, N2O, O3, CO, HNO3, HCl	18km–40km

Model
Four models will provide simulations; they differ in the processes there are able to investigate.

MODEL	Type	Scale	Characteristics	Outputs
FLEXPART (ECMWF)	Trajectories calculations	Global & synoptic	ECMWF fields	Air mass origin
REPROBUS (Partner 4)	Tridimensional chemical transport	Global	Comprehensive chemistry	Chemical species maps and vertical profiles
MIMOSA (ETHER data base)	Tridimensional dynamics	Global & synoptic	High resolution PV advection	Potential vorticity maps
MIMOSA_CHIM (Partner 4)	Tridimensional chemical transport	Global & synoptic	Advection on isentropic surfaces + Comprehensive Chemistry	Tracers (N2O, CH4) maps and vertical profiles

FLEXPART
is an atmospheric trajectory model used by 34 groups from 17 countries. FLEXPART will be driven offline with meteorological input data from the European Centre for Medium Range Weather Forecasts (ECMWF). The model is freeware: http://zardoz.nilu.no/~andreas/flextra+flexpart.html. Trajectory calculations associated with the points on the vertical profiles obtained by the all the balloon instruments give information on the origin of the sounded air masses.

REPROBUS
(Reactive Processes Ruling the Ozone Budget in the Stratosphere) is the stratospheric 3D chemical transport model (CTM) developed at Service d’Aéronomie for more than 10 years (e.g. Lefèvre et al., 1998). Transport and temperatures are driven by the ECMWF operational analysis. The model computes the evolution of 55 species through about 160 photolytic gas-phase and heterogeneous reactions. 40 species or chemical families, typically long-lived tracers, are transported by a semi-Lagrangian code. In StraPolEté will be used the recently improved version of REPROBUS including an explicit description of the inorganic bromine (Br_y) budget. The model is particularly well adapted to follow stratospheric global distribution of tracers and reactive species.

The MIMOSA model
(Modèle Isentropique de transport Mésoéchelle de l’Ozone Stratosphérique par Advection) is based on the advection of PV. It starts from a PV field on an isentropic surface provided by ECMWF analysis and interpolated on a fine horizontal grid that can be chosen at 3 pt/degree or 6 pt/degree. The model creates operationally high resolution PV maps and can be run on various isentropic levels from 350 K upwards (Hauchecorne et al., 2002). PV maps are useful tools to follow large scale isentropic transport.

The 3D CTM MIMOSA-CHIM
(Modele Isentropique de transport Méso-échelle de l´Ozone Stratosphérique par Advection avec CHIMie) is the combination of the dynamical model MIMOSA and the chemistry scheme of 3D CTM REPROBUS (Lefèvre et al., 1998; Tripathi et al., 2006). The diabatic transport of air across isentropic surfaces is computed from the heating rates calculated using the radiation scheme of the SLIMCAT model taken from MIDRAD (Chipperfield et al., 1999). It provides time evolution of 40 chemical species fields with high horizontal resolution and has been developed to follow the detailed transport processes such as filamentations.