HR: 0830h
AN: A51A-13    [Abstracts]
TI: Long-Term Measurements of NO2 at Lauder, New Zealand
AU: Struthers, H
EM: h.strithers@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: Johnston, P V
EM: p.johnston@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: * Kreher, K
EM: k.kreher@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: Liley, B
EM: b.liley@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: McKenzie, R L
EM: r.mckenzie@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: Thomas, A
EM: a.thomas@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: Connor, B
EM: b.connor@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Lauder, Private Bag 50061, Omakau, 9182 New Zealand
AU: Chipperfield, M
EM: martyn@env.leeds.ac.nz
AF: School of the Environment, University of Leeds, Leeds, United Kingdom
AB: Daily NO2 column measurements have been made at Lauder, New Zealand (45S, 170E) since 1980. The measurement technique utilizes the highly structured absorptions by NO2 which are present in sunlight scattered from the zenith sky at twilight (dawn and dusk). The site is well suited to stratospheric observations because of the very clear troposphere and negligible amounts of NO2 in the boundary layer. The importance of nitrogen oxides, in particular the so called NOx species (NO and NO2), in determining stratospheric ozone concentrations has long been recognized. The NOx species catalytically destroy ozone but in the anthropogenically perturbed lower stratosphere, they can inhibit ozone depletion by converting active halogen and hydrogen compounds into their unreactive reservoirs (e.g. ClONO2 and HNO3). The dominant variation in the measured NO2 values at Lauder is the photochemically induced diurnal and annual cycles, with the El Chichon and Pinatubo volcanic eruptions producing significant episodic reductions. Longer-term patterns have also been identified which suggest that NO2 variation may be predicted by major atmospheric cycles: the solar cycle, quasi-biennial oscillation and southern oscillation index. Based on the current estimates of the influence of these atmospheric cycles and volcanic eruptions, the secular trend in the measurements is estimated to be 5% per decade. Convergence of the trend only occurs after a relatively long period of measurement (>15 years). A range of different models have been used to help elucidate aspects of the observed changes in NO2 over Lauder. Results from these studies will be summarized.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0340 Middle atmosphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2005 Joint Assembly