USAP-DC

High latitude deep ice cores contain fundamental records of polar temperatures, atmospheric dust loads (and continental aridity), greenhouse gas concentrations, the status of the biosphere, and other essential properties of past environments. An accurate chronology for these records is needed if their significance is to be fully realized. The dating challenge has stimulated efforts at orbital tuning. In this approach, one varies a timescale, within allowable limits, to optimize the match between a paleoenvironmental property and a curve of insolation through time. The ideal property would vary with time due to direct insolation forcing. It would be unaffected by complex climate feedbacks and teleconnections, and it would give a clean record with high signal/noise ratio. It is argued strongly that the O2/N2 ratio of ice core trapped gases is such a property, and evidence is presented that this property, whose atmospheric ratio is nearly constant, is tied to local summertime insolation. This award will support a project to analyze the O2/N2 ratios at 1 kyr intervals from ~ 115-400 ka in the Vostok ice core. Ancillary measurements will be made of Ar/N2, and Ne/N2 and heavy noble gas ratios, in order to understand bubble close-off fractionation and its manifestation in the Vostok trapped gas record. O2/N2 variations will be matched with summertime insolation at Vostok to achieve a high-accuracy chronology for the Vostok core. The Vostok and other correlatable climate records will then be reexamined to improve our understanding of the dynamics of Pleistocene climate change.

Person	Role
Battle, Mark	Co-Investigator
Bender, Michael	Co-Investigator
Suwa, Makoto	Co-Investigator
Severinghaus, Jeffrey P.	Investigator

Antarctic Glaciology	Award # 0230448
Antarctic Glaciology	Award # 0230260

NSIDC-0311_1
NSIDC-0290_1
severinghaus_0230448

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Firn Air Inert Gas and Oxygen Observations from Siple Dome, 1996, and the South Pole, 2001	PDF	exist
USAP-DC	Trapped Gas Composition and Chronology of the Vostok Ice Core	PDF	exist