FLEXPART transport simulations for the Interantional Polare Year and further model development

Principal Investigator(s)

Dr.Sabine Eckhardt
Norwegian Institute for Air Research
PO Box 100
2027 Kjeller
Norway

sec@nilu.no

Other researchers: John Burkhart, Andreas Stohl, Harald Sodemann

Project description

Introduction

Aerosols have a large effect on radiation transmission in the Arctic troposphere, both directly and indirectly via clouds. We will study transport to the Arctic of aerosols, as well as of air pollution more generally, from anthropogenic sources and boreal forest fires. POLARCAT is an International Polar Year core project and coordinated at our institute. It will address the effects of this pollution on atmospheric chemistry and climate. For interpreting measurement data obtained during the POLARCAT campaigns, we want to perform a large number of FLEXPART simulations with input data from ECMWF.

Model

FLEXPART is a Lagrangian particle dispersion model developed and updated within this working
group (Stohl et al., 1998; Stohl and Thomson, 1999; Stohl et al., 2005) (see http://zardoz.nilu.no/~andreas/flextra+flexpart. html) and used at at least 37 international research institutes. FLEXPART was validated with data from continental scale tracer experiments (Stohl et al., 1998) and was used previously to study the transport of BB emissions into the Arctic (Stohl et al., 2006), as well as the transport of anthropogenic emissions between continents (Stohl et al., 2003) and into the Arctic (Eckhardt et al., 2003). FLEXPART can be driven with analyses from the European Centre for Medium-Range Weather Forecasts (ECMWF, 2002)

Applications

FLEXPART is a very suitable tool for analysing the measured data on various platforms. For
example the influence of anthropogenic and biomass burning emission on air chemistry and aerosol measurements taken from aircraft and at surface stations will be modelled.

Exploration of the horizontal and vertical structure and extent of Arctic Haze, and how it changes
seasonally, using aircraft and surface measurements. Study of the interannual variability in pollution transport pathways to and associated removal mechanisms (e.g., wet deposition) in the Arctic.

Identification of pathways for atmospheric contaminants (so-called persistent organic pollutants)
into the Arctic. FLEXPART has recently been developed to describe the transport of these
substances (Eckhardt et al, 2007) and shall be applied both for case studies as well as for
climatologies of POP transport into the Arctic.

Model Development:

Transport in frontal systems and transport to the Arctic are very often accompanied by rainfall.
Depending on the substances physic-chemical properties scavenging can have major effects on the concentration at the receptor. Most of the algorithms used in various transport model are quite simple and use only few meteorological parameters. Atmospheric removal processes in the
atmosphere will be tested and improved in the model and validated by results from the numerous aircraft measurements which take place during the POLARCAT.

As the resolution of the meteorological data has grown in the last years, there is the need to
optimize the performance and memory management of the models in order to get the most accurate results. FLEXPART will be modified in order to use fine resolution meteorological data and still run in a reasonable time frame.

References:

Eckhardt, S., K. Breivik, S. Manoe, A. Stohl (2007): Record high peaks in PCB concentrations in
the Arctic atmosphere due to long-range transport of biomass burning emissions, Atmos. Chem.
Phys. , 7, 4527-4536.

Stohl, A., M. Hittenberger, and G. Wotawa (1998): Validation of the Lagrangian particle dispersion model FLEXPART against large scale tracer experiments. Atmos. Environ. 32, 4245-4264.

Stohl, A., and D. J. Thomson (1999): A density correction for Lagrangian particle dispersion
models. Bound.-Layer Met. 90, 155-167.

Stohl, A., et al., 2003. A backward modeling study of intercontinental pollution using aircraft
measurements, J. Geophys. Res. , 108, 4370, doi:10.1029/2002JD002862.

Stohl, A., C. Forster, A. Frank, P. Seibert, and G. Wotawa (2005): Technical Note : The Lagrangian particle dispersion model FLEXPART version 6.2. Atmos. Chem. Phys. 5, 2461-2474.

Stohl, A., E. Andrews, J. F. Burkhart, C. Forster, A. Herber, S. W. Hoch, D. Kowal, C. Lunder, T.
Mefford, J. A. Ogren, S. Sharma, N. Spichtinger, K. Stebel, R. Stone, J. Stroem, K. Toerseth, C.
Wehrli, and K. E. Yttri (2006): Pan-Arctic enhancements of light absorbing aerosol concentrations due to North American boreal forest fires during summer 2004. J. Geophys. Res. 111, D22214, doi:10.1029/2006JD007216.

Additional information

New project for 2009

Would accept support for 1 year only, if necessary.