Stratospheric composition measurements in the Arctic and at mid-latitudes and comparison with chemical fields from atmospheric models.

摘要

The purpose of this research is to contribute to our understanding of the processes determining the Arctic stratospheric ozone budget by deploying an ultraviolet-visible spectrometer at the Arctic Stratospheric Ozone Observatory (ASTRO) located at Eureka, NU (80.1°N, 86.4°W). For four years, O 3 columns, NO2 vertical columns and profiles, and OCIO slant columns (in 2000) were measured during polar spring. The spectrometer was also deployed in Vanscoy, SK (52°N, 107°W) in 2000 and 2002 as part of the Middle Atmosphere Nitrogen TRend Assessment (MANTRA) project. The resulting O3 columns were compared with Brewer, TOMS and GOME data. The NO 2 columns, NO2 reference column density (RCD) and NO 2 diurnal variability were also determined.; The Arctic measurements were analysed in detail and combined with infrared Fourier transform spectrometer measurements at ASTRO and with HNO3 measurements at Thule, Greenland (76.5°N, 68.8°W) and Kiruna, Sweden (67.8°N, 20.4°E) (in 2001-2002). To assess the chemical fields of atmospheric models, the observational data set was compared with chemical fields from the Canadian Middle Atmosphere Model (CMAM) and SLIMCAT, a 3D Chemical Transport Model.; The comparison of CMAM with measurements made during the warm Arctic winters (1999, 2001, 2002 and 2003) provided an excellent opportunity to test the model simulations under PSC-free conditions. Generally, the CMAM inter-annual variability is small and does not fully cover the range of the observed variability. SLIMCAT O3 columns were generally higher than the observed values. Comparison with O3 profiles from sondes indicated that O3 mixing in the lower stratosphere was too fast in SLIMCAT. A sensitivity study on the contributions of NO2 RCD uncertainty to the retrieval of NO2 profiles showed that a 10% uncertainty in the RCD changes the retrieved profile by 5-10% at northern high latitudes.; This project extended the temporal-geographical range of polar stratospheric observations and strengthened Canadian capabilities in monitoring the mid-latitude and particularly the Arctic stratosphere. As part of an ongoing research program, it will provide a long-term data set in the Canadian High Arctic, which can be used for future trend analysis.