Analysis of non-methane hydrocarbons in air samples collected aboard the CARIBIC passenger aircraft
The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) is a long-term monitoring program making regular atmospheric measurements from an instrument container installed monthly aboard a passenger aircraft. Typical cruising altitudes of th...
Main Authors: | , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2010-02-01
|
Series: | Atmospheric Measurement Techniques |
Online Access: | http://www.atmos-meas-tech.net/3/311/2010/amt-3-311-2010.pdf |
Summary: | The CARIBIC project (Civil Aircraft for the Regular Investigation of the
atmosphere Based on an Instrument Container) is a long-term monitoring
program making regular atmospheric measurements from an instrument container
installed monthly aboard a passenger aircraft. Typical cruising altitudes of
the aircraft allow for the study of the free troposphere and the
extra-tropical upper troposphere as well as the lowermost stratosphere.
CARIBIC measurements include a number of real time analyses as well as the
collection of aerosol and whole air samples. These whole air samples are
analyzed post-flight for a suite of trace gases, which includes non-methane
hydrocarbons (NMHC).<br>
<br>
The NMHC measurement system and its analytical performance are described
here. Precision was found to vary slightly by compound, and is less than
2% for the C<sub>2</sub>–C<sub>6</sub> alkanes and ethyne, and between 1% and
6% for C<sub>7</sub>–C<sub>8</sub> alkanes and aromatic compounds. Preliminary
results from participation in a Global Atmospheric Watch (WMO) VOC audit
indicate accuracies within the precision of the system. Limits of detection
are 1 pptv for most compounds, and up to 3 pptv for some aromatics. These
are sufficiently low to measure mixing ratios typically observed in the
upper troposphere and lowermost stratosphere for the longer-lived NMHC,
however, in air samples from these regions many of the compounds with
shorter lifetimes (<5 days) were frequently below the detection limit.
Observed NMHC concentrations span several orders of magnitude, dependent on
atmospheric region and air mass history, with concentrations typically
decreasing with shorter chemical lifetimes. |
---|---|
ISSN: | 1867-1381 1867-8548 |