Modeling and simulation of aircraft emissions

General context and motivations

Main objective

The main objective of the project is to better quantify the chemical and radiative atmospheric impacts of aviation at the various scales from the aircraft near field to the global atmosphere. An integrated evaluation of the different steps that involves the emission transformations must be performed, from the gaseous and particulate species generation in the combustion chambers, their chemical and microphysical transformations in the aircraft near field, their vertical and horizontal dilution in the far wake along the contrail path, up to the formation of corridors by the fleets and their transport by the general circulation of the atmosphere. At each of those steps the chemical and radiative atmospheric perturbations must be assessed. This will be done using a hierarchy of numerical models, AVBP and NTMIX from CERFACS and Méso-NHC, Arpège (1D and 3D), MOBIDIC (2D) and MOCAGE (3D) from CNRM.

In addition the atmospheric impact of aviation must be compared to the other sources of pollution, in particular those from surface transportation.

For the period in consideration the objectives of the CERFACS are:

To further develop the NTMIX model for contrail simulation with introduction of an improved microphysics and heterogeneous chemistry.
To investigate the far-field aircraft wake with emphasis on the effects of atmospheric stratification on the vortex dynamics and the wake turbulence.
To develop and validate the coupling between NTMIX and Méso-NH for the simulation of pollutant dispersion and contrails-to-cirrus transition. To obtain a first evaluation of effective emission indices for Noy species.
To update and further develop the linerarized ozone chemical scheme derived from MOBIDIC taking into account NOy perturbations and to validate this approach against MOBIDIC and MOCAGE full chemical simulations.

Main steps

Development of the NTMIX model for contrail simulation.

Simulations of contrail formation with various initial size distributions of exhaust particles have been performed with NTMIX code (Paoli et al., 2004), by implementing a simplified microphysical model for ice condensation. In coordination with F. Garnier from ONERA and Ph. Mirabel from Strasbourg University an updated microphysical model that takes into account interactions with NOx and sulphur chemistry will be implemented. Contrail simulations will then be performed and the non linearity in the chemical system will be assessed.
Simulation at mesoscale: coupling of NTMIX and Méso-NH.

The above simulations will be extended to cover the far-field wake (5 to 10 km from the aircraft). Emphasis will be put on the transition from the contrail 3D structure of the exahust gases and particles trapped into the descending vortex pair, to the quasi-2D cirrus-like shape occurring in the dispersion regime of the wake, after the vortex breakdown. A strategy to couple these simulations to Méegrave;so-NH computations that will cover the 10 to 100 km domain will then be defined, in particular the possible use of a nested version of Méso-NH will be investigated. The overall approach of the mesoscale coupled simulations will be validated using existing observations (in situ and satellite).
Approaches to the linearization of the atmospheric chemistry.

A linearized ozone scheme is used in the Arpege/Climat model. It has been developed by Cariolle and Déqué, 1986 in order to study the interactions between the ozone distribution and the climate evolution. It is computationally efficient and can be used for first rapid assessment of impacts without the need to use more sophisticated chemical models such as MOCAGE, which is much more resource demanding. In order to use the linearized scheme for emission scenarios from aircraft it must be updated to include the heterogeneous chemistry, and the influence on ozone chemical production and destruction rates of the perturbations due to NOy species (mainly NO+NO2 and HNO3), CO and H2O. To this end the MOBIDIC model will be used and comparison with the MOCAGE model will be performed using emissions and/or distributions of perturbed species from the FP5 SCENIC project.

References

[1] Cariolle, D. and M. Déqué: "Southern hemisphere medium-scale waves and total ozone disturbances in a spectral general circulation model", Journal of Geophysical Research, 91,10.825--10.846, 1986.

[2] Paoli, R., J. Hélie, and T. Poinsot: "Contrail formation in aircraft wakes", Journal of Fluid Mechanics, 502, 361-373, 2004.

[3] D. Cariolle, D. Caro, R. Paoli, D. Hauglustaine, B. Cuenot, A. Cozic, and R. Paugam: "Introduction of non-linear plume chemistry into large-scale atmospheric models: application to aircraft emissions", Journal of Geophysical Research, 114, D19302, 2009.

[4] R. Paugam, R. Paoli, and D. Cariolle: "Influence of vortex dynamics and atmospheric turbulence on the early evolution of a contrail", Atmospheric Chemistry and Physics, 10, 3933--3952, 2010.

Partnership

External:

CNRM is the major partner of CERFACS within the program, in particular for development and implementation of Méso-NH, MOBIDIC and Arpège/Climat.
COS. The "Comité d'Orientation Supersonique" supports the project with emphasis on the high altitude impact of aircraft. Additional funding comes from the CCRRDT/ Région Midi-Pyrénées.
ONERA is a partner of CERFACS for the simulation of near field aircraft, contrail formation and associated micophysics.
QUANTIFY. QUANTIFY is an integrated project (IP) that has been selected for funding by the European commission within the 6 framework research program. The project is coordinated by Robert Sausen (DLR). It is a 5 year project starting on 02/2005 with contributions from 40 institutions, among which 2 are from USA and 6 from eastern Europe. The project benefit also from the involvement of industrial manufacturers, AIRBUS in particular. The main objective of the project is to quantify the climate impact of the global transportation system in actual conditions and according to various scenarios for future development. Within this project CERFACS will coordinate the sub-project "Regional dilution and processing" and contribute to the sub-project "Aviation, shipping and clouds".

Internal:

PALM group for the work on linearization of the chemistry

Bibliography

Emission Indices

Contrails and Cirrus

Reports and Theses