Development and application of a new mobile LOPAP instrument for the measurement of HONO altitude profiles in the planetary boundary layer

R. Häseler, T. Brauers, F. Holland, A. Wahner
2009 Atmospheric Measurement Techniques Discussions  
The LOPAP (long path absorption) technique has been shown to be very sensitive for the detection of nitrous acid (HONO) in the atmosphere. However, current instruments were mainly built for ground based applications. Therefore, we designed a new LOPAP instrument to be more versatile for mobile measurements and to meet the requirements 5 for airborne application. The detection limit of the new instrument is below 1 ppt at a time resolution of 5 to 7 min. As a first test, the instrument was
more » ... nstrument was successfully employed during the ZEPTER-1 campaign in July 2007 on board of the Zeppelin NT airship. During 15 flights on six days we measured HONO concentration profiles over southwest Germany, predominantly in the range between 100 m and 650 m above ground level. 10 On average, a mixing ratio of 34 ppt was observed, almost independently of height. Within a second campaign, ZEPTER-2 in fall 2008, higher HONO mixing ratios were observed in the Lake Constance area. Abstract 2029 AMTD 2, Abstract 25 2030 Abstract 20 the fiber from the liquid and reduces the risk of leaks. The size of the dead volume is not affected. We also replaced the spectrometers (Ocean Optics, SD 2000) by new USB spectrometers (OMT, ctf-60) which provide a high stability and low noise. -Electronic I/O interface: the components of the LOPAP-Z (with exception of the 25 spectrometers), are interfaced through one I/O board. This board provides the data and settings of the flow controller, valves, pumps, LEDs, and temperatures 2031 AMTD Abstract 2032 AMTD 2, Abstract 20 wavelengths for the evaluation (Heland et al., 2001) . In this study we used an optical path length of 2.9 m. From the calibrations we calculate an accuracy of 6% which represents the 2-σ error of the sensitivity. The Zeppelin airship and the ZEPTER campaigns The LOPAP-Z instrument was designed and setup in the first half of 2007. During two 25 field campaigns, it was employed on a Zeppelin NT airship for 15 flights in Abstract The LOPAP-Z instrument participated in all flights of both campaigns, however, 2035 AMTD 2, Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Printer-friendly Version Interactive Discussion Schlosser, E., Siese, M., and Wahner, A.: Daytime formation of nitrous acid: a major source of OH radicals in a forest, Geophys. Res. Lett., 32, L05 818, Intercomparison of the DOAS and LOPAP techniques for the detection of nitrous 5 Ammann, M.: Light induced conversion of nitrogen dioxide into nitrous acid on submicron humic acid aerosol, Atmos. Chem. Phys., 7, 4237-4248, 2007,
doi:10.5194/amtd-2-2027-2009 fatcat:dxqa5lsh7zb4bpn6jfe3etahwa