Middle atmospheric ozone, nitrogen dioxide and nitrogen trioxide in?2002–2011: SD-WACCM simulations compared to GOMOS observations

摘要

Most of our understanding of the atmosphere is based on observations and their comparison with model simulations. In middle atmosphere studies it is common practice to use an approach, where the model dynamics are at least partly based on temperature and wind fields from an external meteorological model. In this work we test how closely satellite measurements of a few central trace gases agree with this kind of model simulation. We use collocated vertical profiles where each satellite measurement is compared to the closest model data. We compare profiles and distributions of Osub3/sub, NOsub2/sub and NOsub3/sub from the Global Ozone Monitoring by Occultation of Stars instrument?(GOMOS) on the Envisat satellite with simulations by the Whole Atmosphere Community Climate Model?(WACCM). GOMOS measurements are from nighttime. Our comparisons show that in the stratosphere outside the polar regions differences in ozone between WACCM and GOMOS are small, between 0 and 6%. The correlation of 5-day time series show a very high?0.9–0.95. In the tropical region 10°?S–10°?N below 10?hPa WACCM values are up to 20?% larger than GOMOS. In the Arctic below 6?hPa WACCM ozone values are up to 20?% larger than GOMOS. In the mesosphere between 0.04 and 1?hPa the WACCM is at most 20?% smaller than GOMOS. Above the ozone minimum at 0.01?hPa (or 80?km) large differences are found between WACCM and GOMOS. The correlation can still be high, but at the second ozone peak the correlation falls strongly and the ozone abundance from WACCM is about 60?% smaller than that from GOMOS. The total ozone columns (above 50?hPa) of GOMOS and WACCM agree within ±2?% except in the Arctic where WACCM is 10?% larger than GOMOS. Outside the polar areas and in the validity region of GOMOS NOsub2/sub measurements (0.3–37?hPa) WACCM and GOMOS NOsub2/sub agree within ?5 to +25?% and the correlation is high (0.7–0.95) except in the upper stratosphere at the southern latitudes. In the polar areas, where solar particle precipitation and downward transport from the thermosphere enhance NOsub2/sub abundance, large differences up to ?90?% are found between WACCM and GOMOS NOsub2/sub and the correlation varies between?0.3 and 0.9. For NOsub3/sub, we find that the WACCM and GOMOS difference is between ?20 and 5?% with a very high correlation of?0.7–0.95. We show that NOsub3/sub values strongly depend on temperature and the dependency can be fitted by the exponential function of temperature. The ratio of NOsub3/sub to Osub3/sub from WACCM and GOMOS closely follow the prediction from the equilibrium chemical theory. Abrupt temperature increases from sudden stratospheric warmings?(SSWs) are reflected as sudden enhancements of WACCM and GOMOS NOsub3/sub values.