Start date:
Late August 2009
End date:
Early October 2009
Garwood Valley
Principle Investigator:
Garwood Valley
University of Washington
According to the "snowball earth" hypothesis, climatic changes of the Neoproterozoic time, 600-800 million years ago, included episodes of extreme glaciation, during which ice may have covered nearly the entire ocean for several million years. In tropical regions of net sublimation, ice surfaces may have included: 1) bare, cold sea ice (perhaps cold enough that sodium chloride precipitated); 2) sea ice with a salt crust formed as a lag deposit: and 3) cold glacier ice exposed by sublimation of "sea-glaciers" (self-sustaining ice shelves) flowing from polar seas into the dry tropics. These ice types would have been widespread on the tropical ocean of "snowball earth" but they now exist only in Antarctica. Researchers will study processes that would have been important on an ice-covered ocean during such an event. Their albedos and surface properties will be investigated on naturally-occurring modern analogues: a) bare cold sea ice near the coast of Antarctica in early spring; b) a salt-encrusted lake in the McMurdo Dry Valleys; c) "blue ice" areas of the Transantarctic Mountains that have not experienced melting. For the 2009-2010 season a field team of three will arrive at McMurdo Station during WINFLY so that they can work on the sea ice at temperatures lower than -23C. They will be collaborating with an Antarctic New Zealand winterover sea ice group and will commute daily to their research sites by Piston Bully from McMurdo Station. They will also conduct a shared traverse to Garwood Valley where they wil establish a small field camp for two weeks in order to measure the optical properties of lake ice containing the hydrated salt mirabilite