2010 Workshop:Turbopause
From CedarWiki
Turbopause: measurements, concepts, and implications
Location, Date/Time and Duration
Friday 25 June 2010 0800-1000 and 1030-1230 (as needed) Room ECCR265
Conveners
G. Lehmacher
R. Collins
M. Larsen
Workshop Categories
Altitudes: MLT - Latitudes: global - Inst/Model: modeling - Other: experiment, theory
Format of the Workshop
Panel discussion
Estimated attendance
40
Conflicts with other workshops or Requested Specific Days
Parallel workshops are Recent Advances in Modeling the Ionosphere (0800-1000) Equatorial Aeronomy Across South America (0800-1230) CEDAR Electrodynamics Thermosphere Ionosphere (ETI) Challenge (1030-1230)
Special technology requests
Description
The turbopause can be defined as the atmospheric transition region between the regime of turbulent mixing and the regime of molecular diffusion, and, although spatially and temporarily varying, is mostly between 90 and 110 km altitude. This altitude has been visualized since the 1950s by using sodium release experiments, and has been studied since; however, some issues, such as the impact of wind shears and instabilities at around 100 km, the role for transport of minor species, and the experimental and model determination of diffusion coefficients, are still not well understood.
In February 2009, a rocket salvo was launched from Alaska entitled "Where is the Turbopause? Instabilities, Generation and Development of Turbulence in the 100-km Region". The experiment obtained in situ wind and temperature profiles, neutral and plasma fluctuations, and wave and tidal activity from ground based lidar, radar, and other instrumentation. Among the goals are comparisons of turbulent energy dissipation rates measured by spectral analysis and from chemical trail expansion rates.
This workshop invites presentations about recent results in the experimental determination of the turbopause and related research, but also contributions on modeling the turbopause transition, including parametrization of eddy processes and gravity wave breaking. We also welcome papers on new and alternative concepts of the turbopause besides the diffusion coefficient, such as the "wave turbopause" and the "radar turbopause”.
The proposed format will be a series of 10-15 min key presentations from invited speakers representing their area of expertise, followed by contributed talks, and finally a panel discussion. If you are interested in this workshop, please send an email to the conveners. Student participation is encouraged and talks should be not too specialized.
Schedule
- 08:00 Gerald Lehmacher: Introduction, turbopuase experiments, workshop questions, schedule, 2009 Turbopause experiment
- 08:15 Rich Collins: Turbopause 2009 experiment, stratospheric conditions, lidar results
- 08:30 Tyler Scott: Turbopause 2009 experiment, TMA trails
- 08:45 Jim Hecht: Media:hecht_turbopause.pdf TOMEX: Some thoughts 10+ years after launch, new results from Chile
- 09:00 Miguel Larsen: 2-D and 3-D turbulence, experimental challenges
- 09:20 Cora Randall: Media:randall_abstract.pdf Atmospheric Coupling via Energetic Particle Precipitation
- 09:35 Hanli Liu: large wind shears as related to temperature structures near the turbopause region; modelling challenges
- 09:50 Discussion
- 10:00 Break
- 10:30 Jia Yue: Media:Yue_turbopause.pdf On large wind shears and fast meridional transport near the turbopaus
- 10:45 Liying Qian: Media:Qian_liying_abstract.pdf Impact of Eddy Diffusivity in the Mesopause Region on Seasonal Variations in the Thermosphere
- 11:00 Panel Discussion
- 12:30 Adjourn
Workshop Summary
The workshop was well attended for a time on the last day, approximately 25 attendees including presenters. The presentations covered a range of topics related to turbopause processes: (1) experimental results with an emphasis on the 2009 Turbopause rocket experiments, airglow observations of wave breaking, enhanced NO downward transport in presence and absence of electron precipitation, lidar observations of stability and wind shears at midlatitudes, fast meridional transport of a shuttle plume, (2) modeling results and challenges including 2-D and 3-D turbulence at the turbopause, modeling challenges due to the intermittency of wave input, impact of variable eddy diffusion on thermospheric variability. The discussion demonstrated that there is still a gap in connecting experimental results with modeling. Models must use simplified schemes to describe wave breaking and eddy diffusion, on the other hand, there are only few experiments that capture the small scale processes and instabilities, and it remains a challenging question how to describe them in terms useful for models. More detailed wave forcing in whole atmosphere models may provide answers, as well as more experimental studies of the dynamics of the turbopause.
Presentation Resources
Upload presentation and link to it here. Links to other resources.
- Add links to your presentations here, including agendas, that are uploaded above. Please add bullets to separate talks. See further information on how to upload a file and link to it.
- Media:Lehmacher_ppt_turbopause.pdf | Lehmacher presentation
- Media:Collins_ppt_turbopause.pdf | Collins presentation
- Media:Randall_ppt_turbopause.pdf | Randall presentation
- Media:Liu_ppt_turbopause.pdf | Liu presentation
- Media:Yue_ppt_turbopause.pdf | Yue presentation
- Media:Qian_ppt_turbopause.pdf | Qian presentation
