Startseite
Podcasts
Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 01/05 Podcast
Aufbau und Erprobung eines in-situ NO/NOy-Mess-Systems am Höhenforschungsflugzeug M55-Geophysica

Aufbau und Erprobung eines in-situ NO/NOy-Mess-Systems am Höhenforschungsflugzeug M55-Geophysica

Fakultät für Physik - Digitale Hochschulschriften der LMU - Teil 01/05 vor 22 Jahren

0:00

The fully automated in-situ measuring system SIOUX (StratospherIc
Observation Unit for nitrogen oXides) has been developed and
established under flight conditions. SIOUX is a two channel
measuring device designed for the high-altitude research aircraft
M55-Geophysica to record reactive nitrogen oxides in the upper
troposphere and the lower stratosphere. Channel A detects nitric
oxide (NO) and channel B the total reactive nitrogen (NOy), which
is reduced to NO on the surface of a heated gold-converter in
conjunction with carbon monoxide (CO) as reducing agent. The
technique used for the measurement of NO is chemiluminescence. The
detection limit of channel A is 6 pmol/mol and of channel B 10
pmol/mol for an integration time of 1 s. The main components of
SIOUX are the sample inlet, the detector incorporating the reaction
chambers, photomultipliers and ozone generators, the converter, a
pumping system, a calibration/operation gas system and the data
recording unit. Except for the sample inlet all components are
housed in a pressurised aluminium container. This has a length of
1.1 m, a diameter of 0.6 m and a total mass of 250 kg; the maximum
power consumption of SIOUX is 1300 W. For aeronautical compliance
four test procedures were required to guarantee the flight
compatibility of the mechanics and electronics of the device:
shock/vibration/EMC (ElectroMagnetic Compatibility)/pressure test.
In October 2001 SIOUX was implemented for the first time aboard the
M55-Geophysica during a test campaign in Russia. There, the
measuring system was monitored under flight conditions and its
operation was established for stratospheric conditions. Mixing
ratios for NO and NOy were registered up to an altitude of 20 km.
In July 2002 SIOUX was used aboard the M55-Geophysica for
validation the ENVISAT instrument MIPAS-E in Italy. A comparison
was made for the first time between MIPAS-E measurements of nitric
acid (HNO3) and SIOUX measurements of NOy-NOx (≈ HNO3 in the
altitude range 17 - 20 km). A mean deviation of 20% ± 6% between
the MIPAS-E and the SIOUX data was registered.