End of Season Field Reports

2008-2009 Field Season

Atmospheric, Snow and Firn Chemistry Studies for Interpretation of WAIS-Divide Cores (I-151-M)
NSF-OPP supported
PI: Roger Bales (University of California, Merced)

Field Team:
Wolfgang Rogge and Sylvain Masclin (University of California, Merced)

Season Objectives:
To make concurrent measurements of atmospheric ozone (O3), nitric oxide (NO), formaldehyde (HCHO), hydrogen peroxide (H2O2) and methylhydroperoxide (CH3OOH) of sufficient duration and accuracy to constrain modeling of the atmospheric boundary layer chemistry of HOx radicals (OH+HO2), including diel cycles, snowpack sources and response to changes in surface UV radiation.

Field Season Overview:
Both members of the field team deployed to Antarctica on November 10th, handled cargo in McMurdo, and arrived at WAIS Divide on December 3rd. Much of the 1st 2 weeks was spent on setup of the Polar Haven tent and the instruments at a clean-air site 3.5 km from the main camp. Staff from the main camp worked with the team during this period to establish the satellite camp. Wolfgang Rogge departed WAIS Divide on December 18th, and Sylvain Masclin continued making measurements and collecting samples through January 11th.

The field team sampled the snow surface daily, collected profiles of firn samples from 3 shallow snowpits and twice sampled fresh snow following precipitation events. Each location of the surface snow and snowpit sampling was recorded with a GPS to avoid risk of contamination or artifact during subsequent resampling. All these samples were shipped to UC Merced for analysis of concentrations of nitrate (NO3-), HCHO, H2O2 and CH3OOH.

Continuous atmospheric measurements of HCHO, H2O2, CH3OOH, NO and O3 were made daily. Measurements of O3 were most straightforward, and data quality appears to be excellent. The team had planned to measure vertical profiles of O3, but cargo limits necessitated leaving the profiling equipment in McMurdo. Data quality of NO is also thought to be excellent, with the caveat that calibration gas only arrived at the end of the deployment owing to a mixup. Delay in receipt of reagents for the peroxide detector, problems with the tent heater, and generator problems introduced severe instrument stability problems and limited reliable measurements of HCHO, H2O2, CH3OOH. However, measurements from past ITASE deployments in the area will be used for these species. Firn air was sampled at the site on January 9th and 10th. A weather station (lent by the Crary Lab) was set up at the satellite camp to monitor the wind speed and direction, as generator exhaust can contaminate samples, and record temperature variations, which can influence the atmospheric concentrations.