1. Neutral Winds in the Upper Atmosphere Qian Wu National Center for Atmospheric Research

2. Outline Overview of the upper atmosphere. Ozone heating. Neutral wind tides (the strongest dynamic feature). Why do we need to understand upper atmospheric winds? How do we measure upper atmospheric winds? Observational results. Satellite and Balloon borne instruments.

3. Upper Atmosphere

4. Temperature Profile

5. Forbes, Comparative Aeronomy, 2002

6. Hagan et al. Global Scale Wave Model (GSWM, March)

7. Hagan et al. GSWM (March)

8. Semidiurnal Tide in Meridional Winds Hagan et al. GSWM (June)

10. Phase Comparison

11. Coriolis Force Effect on Tidal Phase Velocity Coriolis force + - + + MeridionalZonal In the Northern Hemisphere In the Southern Hemisphere

12. Dynamics Equations

13. Tidal Wave Function

14. Migrating tidesNonmigrating tides Sun-synchronous westward non Sun-synchronous westward, eastward, standing zonal wavenumber: 1/period(days) (diurnal tide : 1 semidiurnal: 2) zonal wavenumber: any radiative forcing, …latent heat PW/tidal interaction, … comparable to / exceed the migrating tide longitude modulation

15. Why do we need to know upper atmosphere neutral wind tide? Tides are generated in the stratosphere and strongly affected by changes in that region such as: –Gravity wave activities, –Quasi-biennial oscillation (QBO) in the equatorial region –Sudden stratosphere warming in the high latitudes Long term trends in tides may be linked with changes in the stratosphere. Tides also have a great impact on the equatorial ionosphere through dynamo effect.

16. Neutral Wind Measurement

17. Airglow A view from Space Shuttle

18. Airglow Emission Rates Altitude (km) O 5577A OH 8920 A O2 (0,1) 8650A Na 5893 A 97 km 86 km

19. Thermosphere Airglow Emission Rates Altitude (km) O 6300 A

20. Airglow Emission Sources at Night O 6300 Å red line Dissociative recombination Collisional deactivation of N2 O 5577 Å green line Electron impact OH emission

21. Fabry-Perot Interferometer (FPI)

22. Etalon

23. Fabry-Perot Fringe Pattern

24. FPI Configuration Highlights Computerized micrometer Daily laser calibration High degree automation Michigan heritage NCAR enhancement Major Components Sky scanner Filters & filter wheel Etalon & chamber Thermal & pressure control Focusing lens Detector Computer system

25. Instrument Operation FPI OH Airglow Layer North WestEast South Zenith 87 km 174 km 45 deg (a) (b) 174 km

26. FPI at Resolute

28. Instrument Electronics

29. FPI Operational Mode Emission Integration time Wind ErrorsAltitude OH 8920 A3 minutes6 m/s87 km O 5577 A3 minutes1 m/s97 km O 6300 A5 minutes2-6 m/s250 km

30. FPI Fringes 8920 63005577 Laser

31. Mesospheric Wind Semidiurnal Tide

32. Lower Thermospheric Wind Semidiurnal tide

33. TIMED Fact Sheet

34. Limb-Scan Measurements Airglow layer

35. The TIMED Doppler Interferometer (TIDI) is a Fabry-Perot interferometer for measuring winds in the mesosphere and lower thermosphere. Primary measurement: Global neutral wind field, 60–120 km Primary emission observed: O 2 1  (0-0) P9 Additional emissions observed: O 2 1  (0-0) P15, O 2 1  (0-1) P7, O( 1 S) “green line” The TIDI Instrument Telescope Assembly Profiler

36. TIDI Measurement Viewing Directions 1 2 3 4 1 2 3 4 9 minutes Satellite Travel direction

37. TIDI Local Time Coverage Day 80 2002 Shifting 12 minutes per day in local time

39. TIDI Coldside Wind Vectors

40. TIDI Warmside Wind Vectors

41. TIDI Observations

42. Model Winds (GSWM) Oberheide and Hagan

43. Stratosphere Balloon Borne Fabry-Perot Interferometer Allow daytime observation of thermospheric winds due to low solar scatter background at high altitudes. Inexpensive compared to satellite instrument.

44. Summary  Upper atmospheric winds contain strong global scale waves (e.g. tides).  Tides are related to changes in the stratosphere and can affect the ionosphere.  Upper atmospheric winds are the key to a better understanding of the ionosphere.  There is a lack of observation upper atmospheric winds on a global scale.  I see a great opportunity for future balloon and satellite missions.