2002-2003 Science Planning Summary

Oceans & Climate

Dr. Bernhard Lettau
Program Manager

OO-201-O

NSF/OPP 00-03826
Station: McMurdo Station
RPSC POC: Kirk Salveson
Research Site(s): Dome C

Solar radiation on the East Antarctic Plateau
Dr. Stephen G. Warren
University of Washington
Atmospheric Sciences Dept.
sgw@atmos.washington.edu
Dr. Thomas Grenfell
University of Washington

Deploying Team Members: Richard E Brandt . Delphine M Six . Stephen G Warren
Research Objectives: This project is an experimental study of solar radiation processes near the surface at Dome C, the French-Italian station in East Antarctica. It will be carried out in cooperation with the Laboratoire de Glaciologie et Geophysique de l'Environment in Grenoble, France. The emphasis is on the reflection of sunlight by snow and the transmission of sunlight through clouds. The observations researchers gather will be relevant to climate, remote sensing, and the physics of ice and snow.

The research team will measure transmissions of solar radiation through clouds, and these measurements will be used to obtain effective cloud optical depths to estimate cloud radiative forcing, with applications in climate models. They will develop a method to obtain this information from pyranometers alone so that the historical record of solar radiation observations in the antarctic interior can be analyzed for climatological information on clouds.

Observations of the angular pattern of solar radiation reflected from the snow surface will allow the researchers to validate information derived from satellite-derived atmospheric profiles. Using radiative transfer modeling through the atmosphere, the projectís research team will reconcile measured surface reflection functions with the empirical functions obtained from advanced Vidicon high-resolution radiometers on the polar orbiting satellites of the National Oceanic and Atmospheric Administration.

Finally, the spectral peak of snow albedo will be accurately located in order to resolve a discrepancy over the spectral absorption of pure ice in the visible to near-ultraviolet range.


Field Season Overview:
Project team members will travel by fixed-wing aricraft to Dome Concordia (Dome C) and use a portable spectrophotometer and sun photometer to measure the spectral and angular dependence of sunlight reflection by snow, and the spectral transmission of sunlight through clouds on the East Antarctic Plateau at Dome C. The measurements collected may show that the Dome-C region is the optimum antarctic surface for calibrating Earth-observing satellites.

This project is a collaboration with Dr. Michel Fily of the French Polar Research Institute, who will have one participant travelling with this project team. The researchers will be working at the same remote sensing site near Dome C as Dr. Von Walden's group (OO-213-M) and are coordinating research activities with that group.