1. Geography 441/541 S/16 Dr. Christine M. Rodrigue
Mars' Atmosphere
Geography 441/541
S/16
Dr. Christine M. Rodrigue
C.M. Rodrigue, 2016
Geography, CSULB

2. Mars' Atmosphere Mars' atmosphere, weather, and climate
Chemical composition and dustiness
Vertical temperature and pressure structure
Horizontal pressure structure
Winds and the global circulation
Martian weather:
Seasonality
Storms
Mars climate:
Geochemical cycles and weather
Climate zones
Climate change
C.M. Rodrigue, 2016
Geography, CSULB

3. Mars' Atmosphere Atmospheric gas composition: Earth dominated by
Molecular nitrogen (78%)
Molecular oxygen (21%)
Variable amounts of water
Trace amounts of carbon dioxide (0.04%), argon (0.93%), various others
Mars dominated by
Carbon dioxide (95%)
Molecular nitrogen (2.7%)
Argon (1.6%)
Trace amounts of oxygen, carbon monoxide, water vapor, hydrogen
C.M. Rodrigue, 2016
Geography, CSULB

4. Mars' Atmosphere Atmospheric density (p) and altitude (A):
Declines with altitude, as on Earth
Less atmosphere above compressing air
Mars lapse is less steep than Earth's
p = * e * A (Mars) vs. p = * e * A (Earth)
p (kPa); A (m)
C.M. Rodrigue, 2016
Geography, CSULB

5. Mars' Atmosphere Vertical temperature structure
Temperature behavior with altitude defines bands, as on Earth
Less atmosphere above compressing air
C.M. Rodrigue, 2016
Geography, CSULB

6. Mars' Atmosphere Hadley cell: O2 & NO glow 1.27 μm emission (NIR)
ESA MEX OMEGA
C.M. Rodrigue, 2016
Geography, CSULB

7. Mars' Atmosphere Spatial variations in air pressure:
Hadley circulation: temperature + Coriolis force (Wikipedia image)
C.M. Rodrigue, 2016
Geography, CSULB

8. Mars' Atmosphere Spatial variations in air pressure:
Hadley circulation: temperature + Coriolis force
Uplift at equator → low pressure
Air subsides ~45° → higher pressure
Like Earth around equinoces: 2 cells
Unlike Earth around solstices: 1 big cell
C.M. Rodrigue, 2016
Geography, CSULB

9. Mars' Atmosphere Spatial variations in air pressure:
Hadley circulation: temperature + Coriolis force
Uplift at equator → low pressure
Air subsides ~45° → higher pressure
Like Earth around equinoces: 2 cells
Unlike Earth around solstices: 1 big cell
C.M. Rodrigue, 2016
Geography, CSULB

10. Mars' Atmosphere Spatial variations in air pressure:
Hadley circulation: temperature + Coriolis force
Equinox and solstice
C.M. Rodrigue, 2016
Geography, CSULB

11. Martian Weather Temporal variations: Polar cyclones:
Resemble Earth polar hurricanes
Earth to right, Mars below
C.M. Rodrigue, 2016
Geography, CSULB

12. Martian Weather Temporal variations: Air pressure changes
Diurnal patterns (Pathfinder)
Midday spike, sundown pit
Note odd peak around midnight and "wee hours" drop
Complex secondary pattern, with as many as 4 pits and peaks
C.M. Rodrigue, 2016
Geography, CSULB

13. Martian Weather Temporal variations: Air pressure changes
Diurnal patterns
MRO Climate Sounder confirmed Pathfinder data
Found it is global
More pronounced away from equator
Thermal tide creates lows under late
afternoon sun
C.M. Rodrigue, 2016
Geography, CSULB

14. Martian Weather Temporal variations: Air pressure changes
Diurnal patterns
Thermal tide inverse relationship to pressure tide
These create local winds
C.M. Rodrigue, 2016
Geography, CSULB

15. Martian Weather Temporal variations: Air pressure changes
Seasonal patterns
Annual cycles of pressure changes
Huge increase as South Polar ice cap sublimes and starts moving to North Pole
Reverse blip from smaller North Pole effect
C.M. Rodrigue, 2016
Geography, CSULB

16. Mars' Climates Temporal variations: Length of seasons
Unequal (Earth's close to equal in length)
Mars' greater eccentricity
C.M. Rodrigue, 2016
Geography, CSULB

17. Mars' Climates Temporal variations: Thermal inertia
Some materials heat up/cool down quickly (like land surfaces on Earth)
Low specific heat/thermal inertia
This affects diurnal and seasonal temperature contrasts, pressure differences, and winds/breezes: land-and-sea breezes, monsoons
On Mars, high albedo regions (dusty) have low thermal inertia and function like "continents" or inland areas on Earth
Others heat up/cool slowly (like ocean/lake surfaces on Earth)
High specific heat/thermal inertia
On Mars, low albedo surfaces tend to have high thermal inertia and function like "water bodies" on Earth climatologically
C.M. Rodrigue, 2016
Geography, CSULB

18. Mars' Climates
Temporal variations in pressure and wind and spatial variations in albedo
C.M. Rodrigue, 2016
Geography, CSULB

19. Mars' Climates Temporal variations in global circulation: S. summer
C.M. Rodrigue, 2016
Geography, CSULB

20. Mars' Climates
Temporal variations in global circulation: morning at 0°
C.M. Rodrigue, 2016
Geography, CSULB

21. Mars' Climates
Temporal variations in global circulation: afternoon at 0°
C.M. Rodrigue, 2016
Geography, CSULB

22. Mars' Climates
Temporal variations in global circulation: evening at 0°
C.M. Rodrigue, 2016
Geography, CSULB

23. Mars' Climates Cloudiness: Carbon dioxide and water vapor
Pathfinder below
Phoenix to right
C.M. Rodrigue, 2016
Geography, CSULB

24. Mars' Climates Storms: Dust storms (Hubble) and dust devils
(Spirit in Gusev Crater)
C.M. Rodrigue, 2016
Geography, CSULB

25. Mars' Climate Change Polar ice cap accelerated sublimation
C.M. Rodrigue, 2016
Geography, CSULB

26. Mars' Climates Water and nitrogen cycle: Triple point
15N vs. 14N ratio high
Mars lost 90% of its N
Imagining it all back in the atmosphere, we get air pressure ~78 hPa
That would have allowed liquid water
Similarly, deuterium to hydrogen ratio high, ~7-8 x as high as Earth's
Mars must have lost 6.5 times as much water as there is in the modern ice caps!
C.M. Rodrigue, 2016
Geography, CSULB