Spectroscopy and Radiative Transfer – Application to Martian atmosphere

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

2. Earth – Mars Comparison

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

4. Mars atmospheric composition H2O: 10 pr μm~150ppm; 0-80 pr μm O3 : 1 μm-atm=0.1DU~12ppb; 0-60 μm-atm H2O2: 0-40ppb CH4: 10ppb; space / time variability HCHO: 0.5ppm or < 3 ppb? SO2: < 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 HiRISE HiRISE HiRISE SPIRIT

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

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

18. Mesospheric clouds in the Martian atmosphere MOC image OMEGA spectra with CO2 clouds Pathfinder image

19. Thermal Emission Spectrometer spectra

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

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

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

23. Dominated by sun-synchrous diurnal tide

25. 6.5 sol Traveling waves in temperaure (K) at ~25km 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. GCM simulations of m = 3 traveling waves without and with forcing of traveling dust front Control run Traveling dust front increase m=3 waves which enhances further dust lifting

31. Mars photochemistry CO2 + hν → CO + O ; CO2 + hν → CO + O(1D) O + O + CO2 → O2 + CO2; O + O2 + CO2 → O3 + CO2 HOx catalytic chemistry maintaining Martian atmosphere stability O + CO + CO2 → CO2 + CO2 very slow H2O + hν → H + OH; O(1D) + H2O → OH + OH CO + OH → CO2 + H HOx rapidly destroys ozone HO2 + O3 → OH + 2O2 OH + O3 → HO2 + O2 O + HO2 → OH + O2 O + OH → O2 + H heterogeneous chemistry? [Yung and DeMore, 1999]

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

33. Extinction coefficient at 48km

34. 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]

37. [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 [Perrier e tal., 2006] [Fedorova et al., 2006] SPICAM NIR nadir water vapor column abundance

40. High CH4 in localized plumes during N. Summer ~20ppb on average [Mumma et al., 2009] • Conventional model predicts CH4 photochemical lifetime ~300 years • Variations imply recent/continuous release from localized sources • Terrestrial CH4 : 90% by life, 10% geochemical • Life on Mars?