Identification of platform exhaust on the RV Investigator
Oceans cover over 70 % of the Earth's surface. Ship-based measurements are an important component in developing an understanding of atmosphere of this vast region. A common problem that impacts the quality of atmospheric data collected from marine research vessels is exhaust from both diesel co...
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Published in | Atmospheric measurement techniques Vol. 12; no. 6; pp. 3019 - 3038 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
04.06.2019
Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | Oceans cover over
70 % of the Earth's surface. Ship-based measurements are an important
component in developing an understanding of atmosphere of this vast region. A
common problem that impacts the quality of atmospheric data collected from
marine research vessels is exhaust from both diesel combustion and waste
incineration from the ship itself. Described here is an algorithm, developed
for the recently commissioned Australian blue-water research vessel (RV)
Investigator, that identifies exhaust periods in sampled air. The RV
Investigator, with two dedicated atmospheric laboratories,
represents an unprecedented opportunity for high-quality measurements of the
marine atmosphere. The algorithm avoids using ancillary data such as wind
speed and direction, and instead utilises components of the exhaust itself –
aerosol number concentration, black carbon concentration, and carbon monoxide
and carbon dioxide mixing ratios. The exhaust signal is identified within
each of these parameters individually before they are combined and an
additional window filter is applied. The algorithm relies heavily on
statistical methods, rather than setting thresholds that are too rigid to
accommodate potential temporal changes. The algorithm is more effective than
traditional wind-based filters in removing exhaust data without removing
exhaust-free data, which commonly occurs with traditional filters. In
application to the current dataset, the algorithm identifies 26 % of the
wind filter's “clean” data as exhaust, and recovers 5 % of data falsely
removed by the wind filter. With suitable testing, the algorithm has the
potential to be applied to other ship-based atmospheric measurements where
suitable measurements exist. |
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ISSN: | 1867-8548 1867-1381 1867-8548 |
DOI: | 10.5194/amt-12-3019-2019 |