2012-2013 Science Planning Summaries
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Bromide in snow in the sea ice zone
Graduate student Ross Lieb-Lappen erects a tower to collect blowing snow samples. Photo Credit: Ignatius Rigor. 

Program Manager:
Dr. Peter Milne

O-263-M

ASC POC/Implementer:
Addie Coyac / Jessica Jenkins

Dr. Rachel W Obbard (Principal Investigator)
rachel.w.obbard@dartmouth.edu

Dartmouth College
Thayer School of Engineering
Hanover, New Hampshire

Supporting Stations:  McMurdo Station
Research Locations:  Cape Bird Sea Ice

Project Description:
Tropospheric ozone depletion events (ODEs) are a phenomenon associated with the sea ice zone, and are routinely observed in the springtime at coastal locations when incoming winds have traversed sea ice covered areas. ODEs are caused by high levels of bromine gas (BrO and Br). Rapid formation of bromine gas, called the "bromine explosion," requires available seawater brine (containing bromide ions) and a high surface area. Snow on sea ice is thought to provide the bromide (Br) the surface area for this reaction, and the means for Br to enter the boundary layer atmosphere. Meteorological analysis has shown that most Ross Sea locations receive a majority of their wind from the continent from September until November. Historical meteorological records show that the Cape Bird Automatic Weather Station (AWS) receives more than two thirds of its wind from over sea ice.

Field Season Overview:
Two participants will deploy to McMurdo and make helicopter-supported day-trips to the Cape Bird and Marble Point AWS sites. They will use snow machines to collect snow samples within 4 kilometers of McMurdo Station. Cape Bird and Marble Point samples will be collected every-other-day as weather permits. On each visit, they will also collect snow from three locations walking distance apart, and one sea ice core using a Kovacs corer. During a visit early in the field season, they will erect a tower with snow collection and collect samples from it on subsequent visits, and remove it before the end of our sampling.

Deploying Team Members:

  • Ross Lieb-Lappen
  • Rachel Obbard (PI)

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Curator: Esther L. Hill PhD, Antarctic Support Contract   |   NSF Official: Alexandra Isern, Division of Polar Programs