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.

Stratospheric Sudden Warmings (SSWs) followed by the formation of an elevated stratopause at 70-80 km occurred in four of the five recent Arctic winters (2009)(2010)(2011)(2012)(2013). We use global high-latitude temperature measurements from the Solar Occultation for Ice Experiment (SOFIE) to analyze the gravity wave (GW) activity in the upper stratosphere and mesosphere (30-90 km) during different phases of the SSW events. We characterize GW activity in terms of temperature fluctuations and the growth of GW potential energy with altitude. At both 40 and 60 km, compared to the non-SSW year of 2011, the GW activity in the SSW years of 2009, 2010, 2012, and 2013 was reduced after the warming, during the occurrence of an isothermal atmosphere and an elevated stratopause. In contrast, at 80 km the GW activity was highly variable between the individual stratospheric warming events. A case study of GW activity during the 2013 warming event and coincident SOFIE observations of water vapor (H 2 O) from~40 to 90 km indicate a correlation between increase in wave activity at each altitude and the time of descent of dry air. This study supports previous modeling studies' findings that enhanced GW activity is responsible for the downward transport of trace species from the mesosphere to the stratosphere following an SSW event.

We report Rayleigh lidar measurements of nightly temperature profiles in the 40–80 km altitude region and 30 min relative density profiles in the 40–50 km altitude region at Chatanika, Alaska (65°N, 147°W) in December, January, February, and March over two winters (2007–2008, 2008–2009). We characterize the gravity wave activity in terms of the measurements of buoyancy period and relative density fluctuations and estimate the gravity wave potential energy density. We compare these measurements with measurements at Kangerlussuaq, Greenland (67°N, 51°W) and Kühlungsborn, Germany (54°N, 12°E). We use satellite and global meteorological data to analyze the synoptic structure of the stratospheric vortex and the Aleutian anticyclone, the planetary wave activity, and the mean winds. Major stratospheric warmings with displacement of the vortex and splitting of the vortex occurred in 2007–2008 and 2008–2009, respectively. We find a positive correlation between the gravity wave activity in the upper stratosphere and the winds in the stratosphere at all three sites. During January and February 2008, we attribute the lower average potential energy density (1.6 J/kg) at Chatanika (relative to 4.7 J/kg at Kangerlussuaq and 2.6 J/kg at Kühlungsborn) to the blocking of gravity waves by the lower winds in the Aleutian anticyclone, while the higher value at Kangerlussuaq (where the winds are similar in strength to those at Kühlungsborn) may reflect stronger sources of gravity waves. During February and March 2009, we attribute the lower average potential energy density (1.1 J/kg) at both Chatanika and Kühlungsborn to the seasonal decrease of the middle atmosphere winds. In general the gravity wave activity is lowest when the wind is weak at the lowest altitudes. We compare the gravity wave activity and winds in these winters at Chatanika with the winter of 2003–2004, when an extreme warming event occurred resulting in an elevated stratopause and major reduction of gravity wave activity. We find that the 2004 warming had a stronger influence on the gravity wave activity.

[1] We report Rayleigh lidar measurements of nightly temperature profiles in the 40-80 km altitude region and 15 min relative density profiles in the 40-50 km altitude region at Poker Flat Research Range, Chatanika, Alaska (65°N, 147°W), in December, January, and February over three winters (2002-2003, 2003-2004, and 2004-2005). We characterize the gravity wave activity in terms of the measurements of buoyancy period and relative density fluctuations and estimate the potential energy density and growth of potential energy density with altitude. We use satellite and reanalysis data to analyze the synoptic structure of the stratospheric vortex and the Aleutian anticyclone, the planetary wave activity, and the mean winds. These three winters have a major stratospheric warming

Abstract. An ensemble of space-borne and ground-based instruments has been used to evaluate the quality of the version 2.2 temperature retrievals from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). The agreement of ACE-FTS temperatures with other sensors is typically better than 2 K in the stratosphere and upper troposphere and 5 K in the lower mesosphere. There is evidence of a systematic high bias (roughly 3-6 K) in the ACE-FTS temperatures in the mesosphere, and a possible systematic low bias (roughly 2 K) in ACE-FTS temperatures near 23 km. Some ACE-FTS temperature profiles exhibit unphysical oscillations, a problem fixed in preliminary comparisons with temperatures derived using the next version of the ACE-FTS retrieval software. Though these relatively large oscillations in temperature can be on the order of 10 K in the mesosphere, retrieved volume mixing ratio profiles typically vary by less than a percent or so. Statistical comparisons suggest these oscillations occur in about 10% of the retrieved profiles. Analysis from a set of coincident lidar measurements suggests that the random error in ACE-FTS version 2.2 temperatures has a lower limit of about ±2 K.