Technical Note: Characterisation of a DUALER instrument for the airborne measurement of peroxy radicals during AMMA 2006 D. Kartal1, M. D. Andrés-Hernández1, L. Reichert*, H. Schlager2, and J. P. Burrows1 1Institute of Environmental Physics, University of Bremen, Germany 2Institute of Atmospheric Physics, German Aerospace Center (DLR), Oberpfaffenhofen, Germany *formerly at: Institute of Environmental Physics, University of Bremen, Germany
Abstract. A DUALER (dual-channel airborne peroxy radical chemical amplifier)
instrument has been developed and optimised for the airborne measurement of
the total sum of peroxy radicals during the AMMA (African Monsoon
Multidisciplinary Analyses) measurement campaign which took place in Burkina
Faso in August 2006. The innovative feature of the instrument is that both
reactors are sampling simultaneously from a common pre-reactor nozzle while
the whole system is kept at a constant pressure to ensure more signal
stability and accuracy.
Laboratory experiments were conducted to characterise the stability of the
NO2 detector signal and the chain length with the pressure. The results
show that airborne measurements using chemical amplification require
constant pressure at the luminol detector. Wall losses of main peroxy
radicals HO2 and CH3O2 were investigated. The chain length
was experimentally determined for different ambient mixtures and compared
with simulations performed by a chemical box model.
The DUALER instrument was successfully mounted within the German DLR-Falcon.
The analysis of AMMA data utilises a validation procedure based on the
O3 mixing ratios simultaneously measured onboard. The validation and
analysis procedure is illustrated by means of the data measured during the
AMMA campaign. The detection limit and the accuracy of the ambient
measurements are also discussed.
Citation: Kartal, D., Andrés-Hernández, M. D., Reichert, L., Schlager, H., and Burrows, J. P.: Technical Note: Characterisation of a DUALER instrument for the airborne measurement of peroxy radicals during AMMA 2006, Atmos. Chem. Phys., 10, 3047-3062, doi:10.5194/acp-10-3047-2010, 2010.