Arctic winter observations in 2013 by the Solar Occultation for Ice Experiment (SOFIE) show significant transport from the lower-thermosphere to the stratosphere of air enriched in nitric oxide, but depleted in water and methane. The transport is triggered by the Stratospheric Sudden Warming (SSW) on 11 January and is continuously tracked for over 3 months. Ultimately, evidence for lower thermospheric air is seen at 40 km in mid-April. Area integrated nitric oxide (NO) fluxes are compared with previous events in 2004, 2006, and 2009, to show that this event is the second largest in the past 10 years. The SOFIE data are combined with a meteorological analysis to infer descent rates from 40 to 90 km. The descent profile initially peaks near 75 km, shifting downward by approximately 5 km per 10 days. Our work demonstrates the utility of SOFIE tracer measurements in diagnosing vertical transport from the stratosphere to the edge of space.
[1] The Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument operating onboard the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) satellite since 2002 has provided day and nighttime measurements of ozone on a daily basis in the middle to upper atmosphere (15-100 km) using limb scanning in the 9.6-mm band. The focus of this paper is on validation of v1.07 O 3 in the stratosphere and mesosphere region below 70 km. SABER v1.07 O 3 measurements have a precision of $1-2% in the stratosphere and $3-5% in the lower mesosphere. A SABER positive bias exists in all regions other than the lower stratosphere. The positive biases in the stratosphere are within $5-12% in most cases except in the equatorial to middle latitudes in the altitude range $30-50 km, where they reach $15-17% and exceed the combined systematic error by $5-6%. The comparisons in the lower mesosphere indicate that SABER O 3 captures the diurnal variability very well. The best agreement of $5-7% occurs for daytime comparisons with solar occultation measurements in the lower mesosphere. As with most large satellite data sets, a small portion of the O 3 profiles show unrealistically large values. The occurrences of these profiles were revealed using a probability approach, which enabled the identification of the time frames and spatial regions where these anomalies occur.
The interannual variability of the decay of lower stratospheric Arctic vortices is examined using NCEP/NCAR re-analyses between 1958 and 2000. There is large interannual variability in the characteristics of the decay of the vortex air, with very different characteristics for early and late vortex breakups. In early breakup years (when the vortex breaks up in February and early March) the remnants of the vortex survive as coherent potential vorticity structures for around two months, whereas in late breakups (late April and May) the potential vorticity remnants quickly disappear. There is a similar contrast in the stirring around the vortex between early and late breakup years, as diagnosed by the lengthening of material contours in contour advection calculations. In years with an early breakup there is a gradual decrease in the stretching rates from large winter to small summer values, whereas in late breakup years stretching rates are roughly constant until late spring when there is a rapid decrease. These differences in the decay of coherent vortex structures and stirring suggest that there are large differences in the mixing of vortex air into the surrounding middle latitudes between years with early and late breakups.
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