Submitted by the Members* of the United States Contribution to the International Trans Antarctic Scientific Expedition (US ITASE)

*The members of US ITASE include: Mary Albert, Steve Arcone, Roger Bales, David Bromwich, Daniel Dixon, Andrea Isgro, Markus Frey, Tony Gow, Gordon Hamilton, Cobi Harris, Carl Hess, Bob Jacobel, Susan Kaspari, Ursula Leeman, Kirk Maasch, Paul Mayewski (Chief Scientist), Joe McConnell, Debra Meese, Steve Niles, Lynn Peters, David Schneider, Chris Shuman, Blue Spikes, Leigh Stearns, Eric Steig, Brian Welch, James White, Mark Wumkes, Betsy Youngman and Ann Zielinski.

Abstract
On 2 January 2003 the United States component of the International Trans Antarctic Scientific Expedition (US ITASE) arrived at South Pole having completed, over the period 1999-2003, >5000 km of over snow traverses that included much of West Antarctica and a portion of East Antarctica. During the traverses US ITASE focused on the collection of data that will allow the reconstruction of sub-annual scale climate variability and changes in the chemistry of the atmosphere for the last 200+ years. In the process   US  ITASE   collected  an   integrated,

multi-disciplinary assemblage of data extending from the bed of the ice sheet (>3000 m) to >20 km in the atmosphere. Forthcoming results from US ITASE will offer new insights into the understanding of Southern Hemisphere environmental variability, with particular emphasis on atmospheric teleconnections between the Pacific Ocean and West Antarctica.

Introduction
Antarctica is encircled by the world’s most biologically productive oceans, is the largest reservoir of fresh water on the planet, is a major site for the production of the cold deep water that drives global ocean circulation, is a significant influence (through albedo effects) on Earth’s energy budget, and is a crucial driving component for Southern Hemisphere atmospheric circulation. Antarctica thus plays a pivotal role in the coupling of critical components in Earth’s complex climate system. Yet despite its importance, Antarctica is the most poorly documented continent, in a climate sense, over the instrumental era of climate monitoring. Fortunately, it has the potential, through ice core sampling, glacier geophysics, and atmospheric chemistry programs, to be the best understood over multi-decadal to centennial and longer time scales.