To understand the main aspects of the mechanisms involved in the
present-day transfer of some atmospheric constituents from source
regions to the surface snow in Central Greenland.
The specific tasks are 1) to identify sources, source regions and
transport pathways of chemical species to the site, 2) to study
some of the main factors (both physical and chemical) that are
responsible for atmospheric modifications of the chemical
signatures of sources during transport, 3) to investigate the
relationship between the atmospheric phase and the chemical
composition of snow deposited at the surface, including studies
on local vertical transport and incorporation into precipitation,
and 4) to quantify mechanisms responsible for post-deposition
modifications of the chemical profiles in the upper layers of the
firn, for reversibly and irreversibly deposited chemical species.
All of this information will be used by some of the proposers in
the interpretation, in terms of past atmospheric conditions, of
the proxy-records retrieved with the palaeo-ice core data from
the GRIP core.
The project will build on field work, laboratory experiments and
computer modeling. The field aspect will take place at the
Summit of the Greenland Ice Sheet, at the location of the
drilling of the deep ice cores from the GRIP and GISP-2 programs.
It will benefit from preliminary efforts at the same site, that
were aiming at similar goals.
The project will be a collaborative effort with american
researchers, promoting complementarity in the research. The two
programs will share the logistical aspects of the field seasons.
The duration of the project will allow for access at the site in
spring/summer of 1994, 1995 and 1996.
Field work will include atmospheric sampling of aerosol, gases
and precipitation, and simultaneous surface and near surface snow
sampling. Part of the effort will include development of
year-round automatic aerosol and gas samplers. The project will
focus on the most appropriate chemical species for each specific
tasks mentioned above, with the overall transfer also followed
for some elements of major importance in the biogeochemical
cycles in the atmosphere (S, C, N). Laboratory work is intended
for studying more specifically the incorporation of some species
in the snow at the process level, and for deriving coefficients
to be used in parametrizations of the exchange processes.
A preliminary effort for modelling atmospheric transport to the
site is included in the program, as well as tentative modelling
of post deposition processes in relation with firn
Funding SchemeCSC - Cost-sharing contracts
73376 Le Bourget-du-lac