WAIS Divide

The WAIS Divide is the ice flow divide on the West Antarctic Ice Sheet (WAIS) which is a linear boundary that separates the region where the ice flows to the Ross sea, from the region where the ice flows to the Weddell sea. It is similar to a continental hydrographic divide.

The WAIS Divide ice core project (West Antarctic Ice Sheet Divide ice core project) investigated past climate changes, ice sheet dynamics and cryobiology. The project was completed by the United States Antarctic Program(USAP) and was funded by the National Science Foundation (NSF). The focus of the project was to develop records spanning the last ~ 80,000 years of the concentration of greenhouse gases in the atmosphere and Antarctic climate, and to do this with the highest possible time resolution. The project is best known for producing records of atmospheric carbon dioxide and methane with high time resolution and dating accuracy. This was accomplished by collecting and analyzing an ice core from a site named WAIS Divide (79.468° S 112.086° W) that is on the WAIS ice flow divide. This can cause confusion because the name “WAIS Divide” can refer to the WAIS Divide ice flow divide or the WAIS Divide drill site that is at a single spot on the ice flow divide.

Site selection started in 2000 with the goal of finding the best place meeting the following requirements. 1) A site in Antarctica was needed because Greenland ice contains enough dust that post-depositional chemical reactions comprise the record of atmospheric carbon dioxide. 2) A site with minimal horizontal ice flow was needed to avoid complications caused by different ice deposition locations for ice at different depths. This required drilling on an ice flow divide. 3) A site with high annual ice accumulation and thick ice was needed to provide a high time resolution record extending ~80,000 years into the past. This required drilling in West Antarctica which has higher ice accumulation rates than East Antarctica. 5) Other requirements included simple basal topography, avoiding the depth interval of brittle ice during the deglacial part of the record, and logistics considerations.

Site preparation started in the 2005/2006 season with the construction of the skiway, and a steel arch shelter for drilling and core processing. Camp logistics were done by Raytheon polar services. Air transport was provided by the New York Air National Guard using LC-130 aircraft. The deep coring started in the 2006/2007 season using the Deep Ice Sheet Coring (DISC) drill developed and operated by the Ice Drilling Design and Operations group at the University of Wisconsin, Madison. The coring was stopped in December 2011 at a depth of 3,405 m, which is ~ 50 m above the bottom of the ice sheet. The last 50 m of ice was left in place to provide a barrier between the borehole and the pristine aqueous basal environment. The ice at the bottom of the hole fell as snow 67,748 years ago. In the 2012-2013 season additional core was collected in zones of high scientific interest. This was done by drilling through the side of the main bore hole and coring along a path nearly parallel to the main core.

...
Wikipedia