ANTCI is a four
year "collaborative
research" program involving ten major institutions. This program
includes two major field studies (2003 and 2005) in Antarctica
that will be conducted during the spring/summer months of the southern
hemishpere. The broad based goal of this program is to enhance
our
understanding
of
the processes
that control levels of trace chemical
species in the lower atmosphere over the Antarctic continent. The
results will provide a far more comprehensive understanding of
Antarctic atmospheric
chemistry
as well as lead to further insights about the atmospheric factors
that influence the levels and distributions of species in
Antarctic ice cores used to determine past climate. Most important
to this study will be sulfur and nitrogen compounds and the
atmospheric
oxidizing
agents
that modulate
their levels. Major science objectives include: 1) evaluating the
detailed dynamical and chemical processes that control spring/summertime
levels
of the oxides of nitrogen and hydogen at the South Pole; 2) assessing
how representative measurements made at the South Pole and from
previous ground-based coastal studies are to the larger polar and
near shore regions of Antarctica; and 3) investigating the relative
importance of the oxidative processes involved in the coast-to-plateau
transport of reduced sulfur and determing where over the continent
these chemical transition occur. Of lower priority,
are the
following
secondary
objectives: 1b) investigating chemical species in the snow/firn
undergoing extensive exchange with the atmosphere (e.g., NOx, HNO3,
CH2O, H2O2,
and monocarboxylic acids); and 2b) assessing the different chemical
forms of the trace element mercury, Hg, and their relationships to
the levels of O3, OH and other oxidants.
Building on the results from several Antarctic field studies over the last 15 years, especially those from our recent projects SCATE (1994) and ISCAT (1998, 2000), this new study, the Antarctic Tropospheric Chemistry Investigation or ANTCI, entails experimental investigations at the South Pole and extensive airborne sampling. Both the broader chemical scope of the proposed science as well as the use of extensive airborne sampling are reflections of the major new findings from the NSF sponsored ISCAT project. More specifically, the finding that very high and variable levels of NO are present in the atmospheric mixed layer at South Pole has resulted in ANTCI focusing major attention on unraveling oxidation chemistry there. In addition, it is now evident from the ISCAT results that insignificant amounts of reduced sulfur (e.g., marine released dimethylsulfide, DMS) arrive at the South Pole during the Austral spring/summer months. This was found to be true even though the transit time from coastal sources in conjunction with model estimated oxidation rates would strongly suggest otherwise. Collectively, these new findings have shown us an Antarctic troposphere that appears to be very much different than that assumed for planning either of the earlier NSF programs SCATE or ISCAT. Thus, even though the oxidation chemistry of DMS continues to be of great interest and will be pursued in ANTCI, the new findings have necessarily changed the scope of the proposed project so as to address the most fundamental issues in Antarctic tropospheric chemistry. As such several new measurements have had to be added to the original ensemble defined in ISCAT. Many of these measurements incorporate state of the art techniques, while still others will be measured with established more conventional techniques. Almost all species will be sampled simultaneously at a resolution of 5 min or higher. When combined with the available meteorological data, these observations should provide an extraordinarily rich database for use as input into computer models.
The ANTCI program, in addition to its major advancement of Antarctic
atmospheric chemistry, will provided an educational setting for
the training of 5 to 7 new
Ph.Ds. Through continuously updated websites, it will also bring on-going
research activity in Antarctica to other professionals, college
and high school students,
as well as to the general public. Finally, the data generated from these
studies will be archived for all USA investigators to use and
will be exchanged with
international Antarctic research groups operating simultaneously at the coastal
stations of Neumeyer and Halley Bay.
