Dataset: Underway - SO2
Deployment: VDT0410

Underway Sulfur Dioxide Measurements

Notes on Sulfur Dioxide Measurements made during the SAGE Cruise; 27 March to 15 April 2004
Measurements were made using an HPLC technique:
Saltzman, E.S., Yvon, S.A. and Matrai, P.A. 1993. Low-level atmospheric sulfur dioxide measurement
using HPLC/fluorescence detection. J. Atmos. Chem., 17, 73-90

Measurements commenced on 01 April 2004
The following days there were no measurements made:
02 April 2004
07 April 2004
08 April 2004
10 April 2004
11 April 2004
12 April 2004

On these days either the weather was too bad for operation or deployment of the
ship meant that sampling of the stack was highly likely. The inlet of the instrument
was on the seaward side of the Atmospheric Container lab and it was imperative to
ensure that seawater did not enter the inlet, since seawater would have acted as
a sink for sulfur dioxide and would have damaged the nafion drier beyond repair.
In poor weather waves were breaking over the container occasionally, the instrument
was not operated in such conditions.

13 April 2004 was a dedicated "Atmospheric" day and sampling ran for 12 hours,
commencing at 04:15am, to obtain pre-dawn levels of sulfur dioxide.

The cleanest days of the cruise, when the measurements were not significantly affected
by ship emissions were 09 April and 13 April. 09 April 2004 was the cleanest day with
all measurements likely to be from clean background air

A further assessment of how clean samples were, will be made using the CN data at a later stage.

The inlet was at a height of 2m from the deck and 1m from the rail.