Planetary waves in ozone and temperature in the Northern Hemisphere winters of 2002/2003 and early 2005

摘要

Temperature and ozone data from the sub-millimetre radiometer (SMR)installed aboard the Odin satellite have been examined to study therelationship between temperature and ozone concentration in the lower andupper stratosphere in winter time. The retrieved ozone and temperatureprofiles have been considered between the range of 24–46 km during theNorthern Hemisphere (NH) winter of December 2002 to March 2003 and Januaryto March 2005. A comparison between the ozone mixing ratio and temperaturefields has been made for the zonal means, wavenumber one variations and5-day planetary waves. The amplitude values in temperature variations are~5 K in the wavenumber one and 0.5–1 K in the 5-day wave. In ozonemixing ratio, the amplitudes reach ~0.5 ppmv in the wavenumber oneand 0.05–0.1 ppmv in the 5-day wave.Several stratospheric warming events were observed during the NH winters of2002/2003 and early 2005. Along with these warming events, amplification ofthe amplitude has been detected in wavenumber one (up to 30 K in temperatureand 1.25 ppmv in ozone) and partly in the 5-day perturbation (up to 2 K intemperature and 0.2 ppmv in ozone).In general, the results show the expected in-phase behavior between thetemperature and ozone fields in the lower stratosphere due to dynamiceffects, and an out-of-phase pattern in the upper stratosphere, which isexpected as a result of photochemical effects. However, these relationshipsare not valid for zonal means and wavenumber one components when the waveamplitudes are changing dramatically during the strongest stratosphericwarming event (at the end of December 2002/beginning of January 2003). Also,for several shorter intervals, the 5-day perturbations in ozone andtemperature are not well-correlated at lower heights, particularly whenconditions change rapidly.Odin's basic observation schedule provides stratosphere mode data everythird day and to validate the reliability of the 5-day waves extracted fromthe Odin measurements, additional independent data have been analysed inthis study: temperature assimilation data by the European Centre forMedium-range Weather Forecasts (ECMWF) for the NH winter of 2002/2003, andsatellite measurements of temperature and ozone by the Microwave LimbSounder (MLS) on board the Aura satellite for the NH winter in early 2005.Good agreement between the temperature fields from Odin and ECMWF data isfound at middle latitude where, in general, the 5-day perturbations from thetwo data sets coincide in both phase and amplitude throughout the examinedinterval. Analysis of the wavenumber one and the 5-day wave perturbations intemperature and ozone fields from Odin and from Aura demonstrates that, forthe largest part of the examined period, quite similar characteristics arefound in the spatial and temporal domain, with slightly larger amplitudevalues seen by Aura. Hence, the comparison between the Odin data, sampledeach third day, and daily data from Aura and the ECMWF shows that the Odindata are sufficiently reliable to estimate the properties of the 5-dayoscillations, at least for the locations and time intervals with strong waveactivity.