1. Spectroscopy and Radiative Transfer – Application to Martian atmosphere Helen Wang Smithsonian Astrophysical Observatory April 2012

2. Diameter (km)63783397 Gravity(m/s 2 )9.83.7 Tilt of axis (degree)23.525 Day23h, 56 min24h,37min Year (days)365687 Distance to Sun (AU) 11.5 Surface Pressure (mb) 10006 Earth – Mars Comparison

3. Occasional mesospheric clouds on both planets Dust Water ice CO2 ice

4. Mars atmospheric composition H 2 O: 10 pr μm~150ppm; 0-80 pr μm O 3 : 1 μm-atm=0.1DU~12ppb; 0-60 μm-atm H 2 O 2 : 0-40ppb CH 4 : 10ppb; space / time variability HCHO: 0.5ppm or < 3 ppb? SO 2 : < 1-2ppb

6. Mars Albedo Map 1971

7. Mars Albedo Map 2000

8. [Cantor et al., 2007]

9. MSSS

10. Albedo before 2007 global dust storm

11. Albedo after 2007 global dust storm

12. Development of global dust storm from Hellas basin

13. Development of planet-encircling dust storms through flushing events

14. Regional and Local dust storms

15. Dust devils and tracks HiRISE SPIRIT HiRISE

16. Polar hoods and aphelion tropical cloud belt 60S 60N 180W180E N. Winter N. Summer

17. Mars boundary layer water ice clouds and precipitation [Whiteway et al., 2009] LIDAR backscatter observed by the Phoenix lander

18. OMEGA spectra with CO 2 clouds Mesospheric clouds in the Martian atmosphere MOC image Pathfinder image

19. Thermal Emission Spectrometer spectra

20. Seasonal and interannual variations of Martian dust Dust has great impact on Martian atmospheric thermal strucutre [Smith, 2008] MY 24MY 25MY 26

21. water ice water vapor Seasonal & interannual variations of water ice clouds & water vapor Water vapor reflects water exchange among reservoirs in Martian water cycle controls Martian photochemistry, maintains atmos. composition stability [Smith, 2008] MY 24 MY 25MY 26

22. Mars zonal temperature structure during Mars Year 24 [Banfield et al., 2003]

23. Dominated by sun-synchrous diurnal tide

25. Traveling waves in temperaure (K) at ~25km 6.5 sol 20 sol

26. Vertical structure of traveling waves observed in TES temperature 20 sol 6.5 sol

27. Frontal / Flushing Dust Storms

28. Correlation between zonal m=3 traveling waves and flushing dust storms

29. Vertical temperature structure of GCM simulated m = 3 traveling wave Lat m=3 traveling waves are confined to the first scale height

30. Control run GCM simulations of m = 3 traveling waves without and with forcing of traveling dust front Traveling dust front increase m=3 waves which enhances further dust lifting

31. Mars photochemistry CO 2 + hν → CO + O ; CO 2 + hν → CO + O(1D) O + CO + CO 2 → CO 2 + CO 2 very slow heterogeneous chemistry? O + HO 2 → OH + O 2 O + OH → O 2 + H HOx rapidly destroys ozone HO 2 + O 3 → OH + 2O 2 OH + O 3 → HO 2 + O 2 H 2 O + hν → H + OH; CO + OH → CO 2 + H HOx catalytic chemistry maintaining Martian atmosphere stability O(1D) + H 2 O → OH + OH O + O + CO 2 → O 2 + CO 2 ; O + O 2 + CO 2 → O 3 + CO 2 [Yung and DeMore, 1999]

32. Absorption cross section of major absorbing species in the Martian atmosphere

33. Extinction coefficient at 48km

35. Actinic flux at different heights λ>200nm can reach the surface

36. SPICAM UV spectra of Martian atmosphere [Perrier e tal., 2006]

38. SPICAM seasonal evolution of nocturnal ozone layer [Lebonnois et al., 2006]

39. General anti-correlation of ozone and water vapor SPICAM UV nadir ozone column abundance SPICAM NIR nadir water vapor column abundance [Perrier e tal., 2006] [Fedorova et al., 2006]

40. [Mumma et al., 2009] High CH 4 in localized plumes during N. Summer Conventional model predicts CH 4 photochemical lifetime ~300 years Variations imply recent/continuous release from localized sources Terrestrial CH 4 : 90% by life, 10% geochemical Life on Mars? ~20ppb on average