2002-2003 Science Planning Summary

Glaciology

Dr. Julie Palais
Program Manager

IU-158-O

NSF/OPP 98-14810
Station: McMurdo Station
RPSC POC: Kirk Salveson
Research Site(s): Traverse from Byrd Surface Camp to South Pole

U.S. ITASE: Hydrogen peroxide, formaldehyde, and sub-annual snow accumulation in West Antarctica
Dr. Roger Bales
University of Arizona
Department of Hydrology & Water Resources
roger@hwr.arizona.edu
http://www.hwr.arizona.edu/roger/
http://www.hwr.arizona.edu/~Alpine/WAIS/wais.html
Dr. Joseph R. McConnell
Desert Research Institute
jmcconn@dri.edu

Deploying Team Members: See U.S. ITASE Management (IU-153-A)
Research Objectives: Atmospheric photochemistry leaves valuable traces in snow, firn, and ice. It has been verified that the efficiency of atmosphere-to-snow transfer and the preservation of hydrogen peroxide and formaldehyde are both strongly related to temperature and to the rate and timing of snow accumulation. Thus, measurements of these components in the firn and atmosphere will provide data needed to study changes in the tropospheric chemistry of the boundary layer over West Antarctica.

This group will collect samples and take atmospheric measurements along the U.S. ITASE traverses. The wide-ranging extent of these traverses will train the scientific lens upon a variety of locations, covering much of the west antarctic region, and reflecting a range of different depositional environments.

In the study of atmospheric chemistry, it is necessary to estimate the inter-annual patterns of snow accumulation at sub-annual resolution in the pits and cores. This project will measure the concentration of seasonally dependent species (including hydrogen peroxide, nitrate, and chloride) on all samples, which together with stable isotope and ionic analyses by others will provide a highly resolved accumulation record. This project will use a recently developed, physically based, atmosphere-to-snow transfer model to elucidate the photochemistry that led to the concentrations in the snow/firn. These snow chemistry data will also shed light on the inter-annual variability of snow accumulation over a wide spatial range in West Antarctica.

Data developed on current atmospheric levels of hydrogen peroxide, higher peroxides such as methylhydroperoxide, and formaldehyde will constrain model boundary conditions and the state of photochemistry in the austral summer.


Field Season Overview:
The ITASE project team and support contractor staff traverse West Antarctica from Byrd Surface Camp (BSC) to South Pole Station. Two trains pulled by Challenger 55 Caterpillar tractors will transport personnel, instruments, and field camp equipment. Along the way, team members will collect ice cores and surface snow and ice samples, take meteorological readings, and collect radar profiles of the ice sheet. Periodically, Twin Otter aircraft will resupply the traverse team and transport samples back to Byrd Surface Camp. At the end of the traverse, the group will return to McMurdo Station where they will begin to analyze some of their samples. Other samples will be returned to their home institutions.