ABSTRACT

Most of Antarctica is a high plateau of snow-covered ice, whose average temperature is -30°C in summer and -60°C in winter. A steep near-surface temperature inversion in winter is maintained by a balance of longwave radiation; the inversion can be destroyed by clouds and strong wind. The snow surface reflects about 83% of the incident sunlight, helping to maintain the cold climate. Continual snowfall throughout the year keeps the albedo high. Occasional melting occurs on the floating ice shelves and along the coast, but never on the high plateau. Clouds are thinner and lower than elsewhere on Earth. Cirrus ice-clouds are most common, but stratocumulus clouds of liquid droplets are also common in summer at temperatures of -20 to ‑30°C. Annual precipitation averages 17 cm for the whole continent, but is less than 5 cm over much of East Antarctica. Snowfall during occasional storms is supplemented by a nearly continuous fall of tiny "diamond-dust" ice crystals. The wind drifts the surface snow into longitudinal dunes called sastrugi.
About the Speaker:

Stephen Warren received his Ph.D. at Harvard University in 1973. He has been at the University of Washington in Seattle since 1982, where he is now Emeritus Professor of Atmospheric Sciences and Earth & Space Sciences. His research interest is the interaction of solar radiation with snow, clouds, and sea ice, and their role in climate. He has carried out fieldwork in the Southern Ocean, the East Antarctic Plateau, Greenland, Svalbard, Canada, Siberia, and China, with Australian, Russian, French, Danish, Norwegian, Chinese, and U.S. expeditions. He is a Fellow of the American Meteorological Society, the American Association for the Advancement of Science, and the American Geophysical Union. He received a Special Creativity Award from the National Science Foundation, and has been designated a Highly Cited Author by the Institute for Scientific Information. He was Chair of the Advisory Panel for the Alaska Field Site of the Atmospheric Radiation Measurement (ARM) Program. He has been a Council Member of the International Glaciological Society, a member of the U.S.-Russian Working Group on Arctic Climate, the Committee on Atmospheric Radiation of the American Meteorological Society, and the International Commission on Polar Meteorology. He was Station Science Leader of the South Pole Station in 1992. He has about 135 publications, which have been cited about 11,000 times (h-index=45). He teaches classes on climate, atmospheric radiation, glaciology, and scientific writing, and has won two awards for excellence in teaching. He has supervised 8 M.S. students and 12 Ph.D. students. All publications are available at http://www.atmos.washington.edu/~sgw/s_warren_pub.html