BLAST I Homepage
This is the official mission logo. Click on the image
to download an encapsuled postscript file from our public ftp site, it's
called blast94.eps (a compressed version is also available).
The goal of this expedition was twofold: first we intended to use a gas
chromatograph / mass spectrometer (GC/MS) combination and tried to find
out how reliable such an instrument can be out at sea. Secondly, the main
purpose then was to measure methyl bromide (CH3
in the marine air and the surface waters of the East Pacific Ocean and
to determine whether the ocean is a source or a sink for this compound.
Along with methyl bromide, we determined about 20 other compounds in both
air and surface waters. The expedition started in Seattle, WA, crossed
several regions of the East Pacific and reached the inland passage of Chile
at 41°S, and finally Punta Arenas, Chile, at 54°S about 4.5 weeks
after its beginning.
Surface waters along a cruise track in the East Pacific ocean were undersaturated
in methyl bromide (CH3Br) in most areas
except for coastal and upwelling regions, with saturation anomalies ranging
from +100% in coastal waters to -50% in open ocean areas, representing
a regionally weighted mean of -16 (-13 to -20) percent. The partial lifetime
of atmospheric CH3Br with respect to calculated
oceanic degradation along this cruise track is 3.0 (2.9 to 3.6) years.
The global, mean dry mole fraction of CH3Br
in the atmosphere was 9.8±0.6 parts per trillion (ppt) with an interhemispheric
ratio of 1.31±0.08. These data indicate that ~8 percent (0.2 ppt)
of the observed interhemispheric difference in atmospheric CH3Br
could be attributed to an uneven global distribution of oceanic sources
Methods and list of (the most important) measured compounds:
|Gas chromatograph / mass spectrometer combination:
|Gas chromatograph / electron capture detector
From left to right: Steve, Jim, Jürgen, Laurie, and Matt
The NOAA Ship Discoverer, R 102, is about 93m long, cruises at
about 14-16 knots maximum speed, and is staffed with around 50 crew members
with a maximum capacity of about 40 scientists. It was one of the largest
scientific vessels in the NOAA fleet and operated out of Seattle, Washington
until it was retired in 1996. The main laboratory was located on main deck
level close to the stern. The portholes of this lab can be seen in this
picture left of the ladder from the raft that is tied to the ship.
BLAST 94 is shown in blue through the East Pacific Ocean, out of Seattle,
Washington into Punta Arenas, Chile.
Data & Graphs
Data are available on our anonymous FTP account ftp.cmdl.noaa.gov,
see an on-line graph of results from the Science paper.