Soot measurements were carried out by melting & filtering
the snow samples through 0.4 micron nuclepore filters
The filters were then compared with a set of standards
to determine the mass of soot on the filter assuming a
specific absorptance (beta) of 6 m^2 per gm.
Samples were stored frozen and melted immediately before filtering.
The technique worked very well for snow samples but the bacteria in sea ice
clogged the filters almost immediately making the sampling very slow
The ice samples that were processed showed soot concentrations at the background level

The data are contained in 3 files:
SOOTstn - soot observations on the station floes near the des Groseilliers
SOOTffld - soot observations in the far field out to 16 km away from the ship
SOOTice - soot observations of an ice core from a dirty ice area taken in mid-summer

Samples obtained by T. Grenfell, B. Light, M. Sturm, and J. Holmgren
Filtering and Analysis by T. Grenfell and B. Light
tcg@atmos.washington.edu


The presence of particulates in the snow cover and at the ice surface 
can decrease the spectral albedo of the system at visible wavelengths 
where absorption by ice and water is small. Because of this we were 
concerned that the release and local deposition of soot particles ice 
from fuel burned onboard the ship could impact both albedos and melt 
rates. We measured the levels of soot and other contaminants present 
in the snow and ice to allow us to evaluate the role of the background 
particulate levels in the spring and summer radiative energy balance. 
Most of the sampling was carried out on a 4x4 km grid centered on the 
ship, with a few samples taken up to 20 km from the ship. The particles 
were extracted by vacuum filtration of the meltwater immediately after 
melting the samples. The filters were compared on site with a reference 
set for preliminary estimates of mass concentration. They will be brought 
back to our laboratory for more precise analysis of composition and 
particle size distribution. As the plot indicates, ship contamination 
was not a factor in our measurements.