1. 1 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Scott M. Bailey AIM Deputy Principal Investigator University of Alaska scott.bailey@gi.alaska.edu 907-474-7741 Noctilucent Clouds A miners’ canary for global change?

2. 2 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Aeronomy of Ice in the Mesosphere (AIM) Ken Sassen, Alaska To Ground-based observers: Noctilucent or “night shining” Clouds (NLCs) To Satellite observers: Polar Mesospheric Clouds (PMCs)

3. 3 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Why do noctilucent clouds shine at night? NLC 83 km Clouds occur 50 miles above the earth surface causing them to be illuminated after sunset

4. 4 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey PMCs display complicated structure driven by atmospheric dynamics Bands Billows Timo Leponiemi, 2001

5. 5 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey

6. 6 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey

7. 7 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey

8. 8 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Space Station NLC Photograph Donald Pettit, Space Station Science Officer

9. 9 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NLCs were NOT observed before 1850. Fogle, 1965

10. 10 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Krakatoa injected water into the stratosphere

11. 11 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NLC occurrence is increasing. NLC occurrence is increasing. Thomas and Olivero, 2001

12. 12 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NH NLC Occurrence Frequency is Increasing Northern Hemisphere Observations by SBUV NLC Occurrence Frequency (%) Time Adapted from Deland et al., 2003 From SBUV

13. 13 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Measurements show bright cloud frequency has increased. Satellite Measurements Reveal Brighter Clouds after SME Shettle et al., 2002

14. 14 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NLCs usually occur in the polar regions during a 12 week period centered about two weeks after solstice SME defined the NLC climatology 20 years ago

15. 15 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey A Spectacular but Unexpected Event: June 22, 1999 A Spectacular but Unexpected Event: June 22, 1999 An NLC is observed and photographed at 40 o latitude for the first time!

16. 16 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Low latitude PMC event; June 23, 1999 Aimee Merkel SNOE data

17. 17 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NLC increases at the beginning of the northern season SBUV data analyzed for: 50 o N to 70 o N 20 to 40 days before summer solstice Rusch, 2003

18. 18 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey NLCs are changing NLCs at 42 o N for first time in history (Logan, Utah on June 22-23, 1999) Why are NLCs increasing in frequency and brightness? Why were they sighted at ~40 o N nearly every year now when usually they have only been seen poleward of 55 o ?

19. 19 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Are NLCs the “miner’s canary” of global change in the upper atmosphere? NLCs are changing NLCs at 42 o N for first time in history (Logan, Utah on June 22-23, 1999) Why are NLCs increasing in frequency and brightness? Why were they sighted at ~40 o N for 3 consecutive summers (1999, 2000 and 2001) when usually they are seen poleward of 55 o ?

20. 20 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey What do we know about NLC formation? NLC formation requires cold temperatures; thus global CO 2 changes may be one cause of increasing NLCs - CO 2 buildup in the lower atmosphere causes warming, but increases in the upper atmosphere should cause cooling H 2 O chemistry must be important since NLCs consist of water ice Poor knowledge exists of how NLCs nucleate, the environment for nucleation and how the mesosphere responds to forcings

21. 21 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Why do they form? What is the role of temperature, H 2 O, dynamics, and chemistry? AIM will address the critical questions

22. 22 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Why do they vary? Do extraterrestrial forcings such as cosmic dust or ionization play a role? AIM will address the critical questions Why do they form? What is the role of temperature, H 2 O, dynamics, and chemistry?

23. 23 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Why have they appeared at such low latitudes (~ 40  N) in recent NH summers? AIM will address the critical questions Why do they vary? Do extraterrestrial forcings such as cosmic dust or ionization play a role? Why do they form? What is the role of temperature, H 2 O, dynamics, and chemistry?

24. 24 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Is there a relationship to global change? AIM will address the critical questions Why have they appeared at such low latitudes (~ 40  N) in 3 recent NH summers? Why do they vary? Do extraterrestrial forcings such as cosmic dust or ionization play a role? Why do they form? What is the role of temperature, H 2 O, dynamics, and chemistry?

25. 25 AIM EPO Teacher Workshop, July 24, 2006 Scott Bailey Resolve why NLCs form and how and why they vary Quantify the connection between the clouds and the meteorology of the polar mesosphere by measuring the thermal, chemical and dynamical environment in which NLCs form Provide the basis for study of long-term variability in the mesospheric climate and its relationship to global change AIM goals are clearly defined