ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-3-2127-2003 Intercomparison of aircraft instruments on board the C-130 and Falcon 20 over southern Germany during EXPORT 2000 Brough N. 1 Reeves C. E. 1 Penkett S. A. 1 Stewart D. J. 1 Dewey K. 2 Kent J. 2 Barjat H. 2 Monks P. S. 3 Ziereis H. 4 Stock P. 4 Huntrieser H. 4 Schlager H. 4 School of Environmental Sciences, University of East Anglia, Norwich, UK Meteorological Research Flight (MRF), Atmospheric Chemistry Group, UK Meteorological Office, Bracknell, UK Department of Chemistry, University of Leicester, Leicester, UK Institute für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany 03 12 2003 3 6 2127 2138 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/3/2127/2003/acp-3-2127-2003.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/3/2127/2003/acp-3-2127-2003.pdf

In the summer 2000 EXPORT aircraft campaign (European eXport of Precursors and Ozone by long-Range Transport), two comprehensively instrumented research aircraft measuring a variety of chemical species flew wing tip to wing tip for a period of one and a quarter hours. During this interval a comparison was undertaken of the measurements of nitrogen oxide (NO), odd nitrogen species (NO<sub>y</sub>), carbon monoxide (CO) and ozone (O<sub>3</sub>). The comparison was performed at two different flight levels, which provided a 10-fold variation in the concentrations of both NO (10 to 1000 parts per trillion by volume (pptv)) and NO<sub>y</sub> (200 to over 2500 pptv). Large peaks of NO and NO<sub>y</sub> observed from the Falcon 20, which were at first thought to be from the exhaust of the C-130, were also detected on the 4 channel NO<sub>xy</sub> instrument aboard the C-130. These peaks were a good indication that both aircraft were in the same air mass and that the Falcon 20 was not in the exhaust plume of the C-130. Correlations and statistical analysis are presented between the instruments used on the two separate aircraft platforms. These were found to be in good agreement giving a high degree of correlation for the ambient air studied. Any deviations from the correlations are accounted for in the estimated inaccuracies of the instruments. These results help to establish that the instruments aboard the separate aircraft are reliably able to measure the corresponding chemical species in the range of conditions sampled and that data collected by both aircraft can be co-ordinated for purposes of interpretation.