Conveners:
Chiao-Yao (Joe) She (joeshe@lamar.colostate.edu)
Qian Wu (qwu@ucar.edu)
2005 Wednesday 29 June 0130 - 0330 PM
Approximately 50 people attended the workshop. Non-speaker audiences include Jeff Forbes, Maura Hagan, Murry Salby, Dave Fritts, Sam Yee, Phil Richards, Scott Palo, Xinzhao Zhu, Vincent Wickwar, and others adding much to the discussion that enhanced our understanding of observations reported. Speakers were asked to describe collaborative research using satellite and ground based observations in MLT region. Some speakers and audiences discussed the benefit of the combining the space-based and ground-based observations. Particularly, the satellite observations of the two day wave are of interest to many ground based investigators.
Prof. Chiao-Yao (Joe) She (Colorado State University) started the workshop by providing an overview pointing out the importance of synergistic studies with both ground-based (GB) and satellite observations, to help fine-tune the algorithm and to provide complementary (high spatial resolution vs. global) information. Joe then turned to the recent observations by the ODIN Odin/OSIRIS satellite on global sodium layers. The work was jointly done by Dr. John Plane and his student, Zeyu Fan, and Chiao-Yao She with Joe supplying the GB lidar data. While overpass comparisons between the satellite and ground based lidar measurements at Ft. Collins initially helped to establish the retrieval algorithm, and to reveal or confirm the ~2 km altitude offset in the limb observation, the resultant retrieval showed very good agreement, although an offset of the 2 km in height was noted. The ground based measurements not only helped correct the altitude offset, they also provide necessary information for the development of the retrieval algorithm. In the end, the satellite observations were able to provide a global view of the sodium layer distribution, confirming ice particle-sodium anti-correlation in the polar region summer and dramatizing diurnal perturbations in the equatorial region. Since OSIRIS is a Canadian instrument, an alternative title for the talk could be "Swedish God Odin uses Canadian instrument to observe Na day-glow, and British chemistry Guru retrieves global Na layers".
Dr. Tao Li (Colorado State University) presented analysis results for a 9-day continuous lidar MLT temperature and wind observations in 2003 of low-pass filtered contour plots of temperature, zonal and meridional winds in August 2002, 2003 and 2004, revealing a quasi two day wave (QTD) signal. The variations in the diurnal and semidiurnal tides were examined. Planetary waves were also observed in the lidar data set. Comparisons with TIMED SABER temperatures in all 3 years and TIDI wind measurements in 2004 were made. Consistent results on S=3 and S=4 quasi-two-day waves were noted. It is interesting to note that both lidar and SABER showed stronger QTD activities in 2002 and 2004 than in 2003, implicating quasi-biennial oscillation.
Dr. Yucheng Zhao (Utah State University) gave a brief description on her recent work with Mike Taylor on comparisons between ground based temperature mapper data and comparisons with SABER. She talked about her effort to extract the annual and semiannual oscillations and the difficulty due to limited local time coverage of both the satellite and ground based optical measurements.
Dr. Jeremy Winick (Air Force Research Lab.) presented recent results from SABER observations of temperature-inversion layers in conjunction with ground based measurements. He noted that TILs are associated with tidal phase at low latitudes. SABER revealed their spatial extent to be larger than anticipated, 1000-5000 km or more along the TIMED orbital track. Large inversions provide a duct for bores. Extended collaboration with ground based data can be very useful for the bore study.
Dr. Irfan Azeem (Embry Riddle Aeronautic University) described his recent work on the 4-day wave over the South Pole in the mesospheric temperature before and during a stratosphere warming event obtained from a Michelson interferometer. More study with satellite observations will help to determine the extent of the 4-day wave and its zonal wavenumber.
Dr. Qian Wu (NCAR) gave an overview of the TIDI observational results from migrating diurnal and semidiurnal tides. Comparisons between TIDI observations and ground based meteor radar data were made and showed promising consistency. In addition, a non-migrating diurnal tide analysis was also discussed. Moreover, the two-day wave and comparisons with observations from AURA satellite MLS data were also shown during the talk.
Dr. Hanli Liu (NCAR) showed his model simulation (with TIME-GCM) of tidal and planetary wave interactions. The focus was on the 9-day continuous observations by the CSU lidar observation. Overall, he was able to reproduce many of the features in the lidar and TIMED SABER and TIDI data. The results imply the possibility of planetary wave effects on the tidal waves in mid-latitudes.