Weather and Climate on Mars

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Weather and Climate on Mars

• Joshua L. Bandfield
• Arizona State University

THEMIS IR image of the Martian limb (NASA/JPL/ASU)
2
Overview

• Some basics about Mars
• Orbit, atmosphere, etc
• Mars seasons and weather
• What is the day to day weather like?
• Martian climate
• How does the climate change over long time
  periods?

3
Mars Facts

• Year 687 days
• Day 24.67 hours
• Distance from the sun 1.5 AU
• (Earth 1 AU)
• Tilt 25.19 degrees
• (Earth 23.45 degrees)
• Radius 3390 km
• (Earth 6371 km)
• Surface pressure 6.36 mbar
• (Earth 1000 mbar)
• Atmosphere 95.3 CO2
• 2.7 N2
• 1.6 Ar

4
More Mars Facts

• Polar Caps are made of CO2 and H2O ice
• Atmospheric pressure is too low for liquid water
  to be stable
• Dry conditions make lots of loose dust and sand
• Surface temperatures vary from -123 C to 35 C

5
Mars Elliptical Orbit

• Closer to the sun during Southern summer
• Causes more intense southern summers and northern
  winters

NASA CMEX (M. Caplinger)
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Temperatures and Season
Northern Summer

• Temperature slice of the Martian atmosphere
• Orange and red is warm (-50 C) Blue and purple
  is cold (-120 C)

Altitude
S. Pole
N. Pole
NASA/JPL/GSFC
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Temperatures and Season
Northern Fall

• Temperature slice of the Martian atmosphere
• Orange and red is warm (-50 C) Blue and purple
  is cold (-120 C)

Altitude
S. Pole
N. Pole
NASA/JPL/GSFC
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Temperatures and Season
Northern Winter

• Temperature slice of the Martian atmosphere
• Orange and red is warm (-50 C) Blue and purple
  is cold (-120 C)

Altitude
S. Pole
N. Pole
NASA/JPL/GSFC
9
Temperatures and Season
Northern Spring

• Temperature slice of the Martian atmosphere
• Orange and red is warm (-50 C) Blue and purple
  is cold (-120 C)

Altitude
S. Pole
N. Pole
NASA/JPL/GSFC
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Temperatures and Season
NASA/JPL/GSFC
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Polar Caps and Mars Atmosphere

• Unlike Earth, the Martian atmosphere can freeze
  directly at the polar caps

Mars North Pole
Mars South Pole
NASA/JPL/MSSS
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Mars Atmospheric Pressure

• Changes throughout the year as CO2 freezes and
  sublimates at the polar caps

9 mbar
8
Pressure
7
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Northern Spring
N. Summer
N. Fall
N. Winter
Season
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Martian Dust
NASA/JPL/MSSS
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Martian Dust

• Mars atmosphere is always dusty
• From dust devils and dust storms
• More dust is present during the more intense
  southern summer

Dust Storm Near Mars North Pole
NASA/JPL/MSSS
15
NASA Earth Observatory
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NASA/JPL/MSSS
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June 10, 2001
NASA/JPL/MSSS
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July 31, 2001
NASA/JPL/MSSS
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Atmospheric Temperatures and Dust

• When the dust abundance is relatively low the
  atmospheric temperatures are also low

Global temperature and dust maps ?
NASA/JPL/ASU
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Atmospheric Temperatures and Dust

• When the dust abundance is relatively high the
  atmospheric temperatures are also high

Global temperature and dust maps ?
NASA/JPL/ASU
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Effects of Dust

• Dust absorbs sunlight and heats up the atmosphere
• During global dust storms high dust abundances
  shade and cool the surface
• This stabilizes the atmosphere and allows dust to
  settle out

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Dust Devils

• Dust devils vacuum dust up from the surface and
  pump it into the atmosphere
• Dust devils form with intense heating of the air
  near the surface
• Martian dust devils have been seen to be several
  kilometers tall!

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Dust Devils At Gusev Crater
NASA/JPL
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Dust Devils and Tracks
NASA/JPL/MSSS
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Dust Devil Tracks

• Dust Devil tracks form seasonally

NASA/JPL/ASU
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Mars Ice Clouds
NASA/JPL

• Martian ice clouds are much like Earth

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Equatorial Cloud Belt

• Mars has a cloudy season near the equator during
  northern summer

Global water ice cloud abundance map (yellow,
orange, and red indicate thick clouds)
Latitude
West Longitude
NASA/JPL/GSFC
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ESA/DLR/FU Berlin
Morning Ice Fog in Valles Marineris
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Martian Climate

• Climate is long term weather patterns
• Climate is predictable, weather isnt
• Mars climate appears to have periodic cycles in
  addition to long term changes over the planets
  history

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Martian Climate Cycles

• Changes in tilt, wobble, and eccentricity of Mars
  and its orbit have dramatic effects on its
  climate
• Similar cycles on Earth causes ice ages and warm
  periods

NASA CMEX (M. Caplinger)
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Martian Climate Cycles

• Mars appears to show remnant ice features from
  its last ice age
• These cycles last for 10,000 year time scales

NASA/JPL/ASU
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Layers of dust and ice on Mars may record recent
climate cycles

• CO2 Frost forms over many surfaces annually

NASA/JPL/MSSS
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Long Term Climate Change
NASA/JPL/ASU
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Delta on Mars
NASA/JPL/MSSS
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Long Term Climate Change

• Liquid water appears to have been stable for some
  period on the surface of Mars
• This requires a thicker atmosphere
• Probably also warmer temperatures
• Where did the atmosphere go??
• Mars lower gravity and lack of magnetic field
  allows at least some of it to escape to space
  over time

36
Long Term Climate Change

• At least some of Mars atmosphere is also in the
  rocks!
• Atmospheric CO2 is used to create carbonate rocks
• Mars doesnt have plate tectonics to heat up and
  decompose carbonates back to CO2 to complete the
  cycle

NASA Earth Observatory
37
NASA/JPL/MSSS