Thermal anomalies in Central Elysium Planitia andArsia Mons.
Evidence and implications of aerothermal systems

Téodolina LOPEZ
PhD Advisors : David BaratouxMichel Rabinowicz

Seminar in Kobe Institute12/10/2009

A new word

Hydrothermal system

Water

Aerothermal system

Air

Contents
I/ Introduction
1) Recent finding : Aerothermal systems in terrestrial volcanic soils
Application to Mars : search for aerothermal systems in permeable soils
II/ Martian surface temperature
1) Data
2) Interpretation
III/ Part. 1: Case of Cerberus Fossae
1) Geological setting and morphology
2) Thermal study3) Modelling the aerothermal system
IV/ Part. 2: Case of Arsia Mons’ skylights
1) Geological setting and geometric characteristics
2) Thermal study3) Local and regional aerothermal systems at Arsia Mons
V/Conclusion

Location of Formica Léo

Antoine et al., JVGR 2009
Introduction

Aerothermal systems in terrestrial volcanic soils

Location

Formica Léoa) Blocks : bottom SE crater (A)b) Fine lapillis: top of Formica Leo (D)Picture of Formica Léo with the classes
material location.
Antoine et al., JVGR 2009
Introduction

Aerothermal systems in terrestrial volcanic soils

Formica Léo

Thermal study

Midnight surface temperature profiles of the two craters. A
drop of about 3K is observed from the rim crest to the crater
center.

Thermal images of Formica Léo during
night. Craters bottom are cold while therim crests are warm.
Introduction

Aerothermal systems in terrestrial volcanic soils

Formica Léo

Antoine et al., JVGR 2009

Thermal conductivity• Definition : It is the property of a material that indicates its ability to conduct
heat. It is expressed in Watt/Kelvin/meters.

Presley and Christensen (1997) have shown that
thermal conductivity increases with increasing
particle size and atmospheric pressure.

Piqueux and Christensen (2009) : Their thermal model reproduces the thermal
conductivity dependency of a sample with grain size and pressure and also
confirms that higher porosities generally lead to lower conductivities.
Introduction

Aerothermal systems in terrestrial volcanic soils

2D Numerical model _ Presentation
Antoine et al., JVGR 2009

Representation of the box
used for the airconvection model.
Equations of the model:

Ra = ρa g α ΔT H K / μ κRaeq = γ Ra

Notation and values used for the model
Introduction

Aerothermal systems in terrestrial volcanic soils

Formica Léo

2D Numerical model _ Resultsa) Surfaces temperatures calculated atdifferent times for a Raeq = 45 (dottedlines). Explains the observed rim crest tocrater center temperature drop.

b)

Surfaces temperatures calculated at
different times for a Raeq = 6000 (dottedlines). Fit the observed temperature shape,
while its amplitude is twice as large.

Air convection within the craters can explain the observed
temperature pattern.
Antoine et al., JVGR 2009
Introduction

Aerothermal systems in terrestrial volcanic soils

Formica Léo

Measurements of Spontaneous Potential (SP)

Picture of Formica Léo
with the SP profiles (P1to P5).

SP profiles (solid lines) and temperature profiles extrat from thethermal images (dotted lines).

Air convection within the craters can have an influence on the SP patterns.
Antoine et al., submitted 2009
Introduction

Aerothermal systems in terrestrial volcanic soils

Formica Léo

Air convection at the scale of Piton de la Fournaise
Antoine et al., submitted 2009a) Piton de la Fournaise SP map. Twopeaks, reaching 2V, are observedon the terminal cone.
b) Possible link with the meteoritic
water infiltration.

a - b) Pluricentimetric and plurimetric fractures near
the Bory-Dolomieu Caldera.
c – d) Fractures thermal images near the caldera (4 a.m)Introduction

Aerothermal systems in terrestrial volcanic soils

Piton de la Fournaise

Air convection at the scale of Piton de la Fournaise

Like for Formica Léo, the existence of hot fractures at the Dolomieu edges
can be explained by air convection. This air convection can have an impact in
the SP pattern observed on this volcano.

Antoine et al., submitted 2009
Introduction

Aerothermal systems in terrestrial volcanic soils

Piton de la Fournaise

Contents
I/ Introduction
1) Recent finding : Aerothermal systems in terrestrial volcanic soils
Application to Mars : search for aerothermal systems in permeable soils
II/ Martian surface temperature
1) Data
2) Interpretation
III/ Part. 1: Case of Cerberus Fossae
1) Geological setting and morphology
2) Thermal study3) Modelling the aerothermal system
IVI/ Part. 2: Case of Arsia Mons’ skylights
1) Geological setting and geometric characteristics
2) Thermal study3) Local and regional aerothermal systems at Arsia Mons
V/Conclusion

Thermal data on MarsN

10.40• Radiance at the sensor,• Surface temperature obtained by theblack-body’s law.
161.109.20

Introduction

Martian surface temperature

DataSurface Temperature : energy balance( Mellon et al, 2000)

S/R² (1-A) cos(i) + FIR + L ∂m/∂t + I √(π/P * ∂T/ ∂z’) = ε σT4S
• 1st term Insolation :S = solar flux, R = orbital radius, A = surface albedo, i = incidence angle.
• 2 nd term Thermal Radiation of atmosphere• 3 rd term Saisonal CO2 condensation:
L = CO2 latent heat of sublimation , m = mass of CO2 frost.
• 4th term : Subsurface conduction:
I = thermal inertia, P = diurnal period, T = temperature, z’ = depth normalised• 5 th term Radiations lost in space :ε = emissivity of the soil surface or CO2, σ = Stefan-Boltzann constant, Ts = surfacetemperature.
Martian surface temperature

DataThermal inertia• Definition :I = thermal inertia (J/m²/K/s1/2)

I = √ (kρc)

k = thermal conductivity (W/K/m)
ρ = density (kg/m3)
c = thermal capacity (J/kg/K)• Practically : It is the ability of the sub-surface to conduct and store
heat energy away from the surface during day and to return thatenergy to the surface during the night.

Martian surface temperature

DataWhy temperature is varying?

Influence of the thermal inertia, the albedo, the surface pressure and the dust opacity on the variation ofdiurnal surface temperature ( Mellon et al, 2000)
Martian surface temperature

Interpretation

Standard uses of thermal data

Martian surface temperature

Interpretation

Standard uses of thermal data

Mangold et al., EPSL 2009
Martian surface temperature

Interpretation

Contents
I/ Introduction
1) Recent finding : Aerothermal systems in terrestrial volcanic soils
Application to Mars : search for aerothermal systems in permeable soils
II/ Martian surface temperature
1) Data
2) Interpretation
III/ Part. 1: Case of Cerberus Fossae
1) Geological setting and morphology
2) Thermal study3) Modelling the aerothermal systemIV/ Part. 2: Case of Arsia Mons’ skylights
1) Geological setting and geometric characteristics
2) Thermal study3) Local and regional aerothermal systems at Arsia Mons
V/Conclusion

Cerberus Fossae

Context map : Location
Central Elysium Planitia.

Central Elysium Planitia
Cerberus Fossae

Geological settingof

Cerberus Fossae
N

Central Elysium Planitia

•
•
•
•

Young volcanic plain,
Fracture width: 2 km,
Fracture depth: 600 m,
Slope ≈ 30°.

Cerberus Fossae

Morphology

10 kmInfrared image• Two superposed thermal images inbrightness temperature,• Area warmer ≈ 220 K,• Fracture center cold ≈ 190 K.
Relation between lithology andobserved thermal behaviour?

N

10.40

161.109.20

Antoine, Lopez et al., submitted 2009
Cerberus Fossae

Morphology

Lithology _ Bedrocks

Antoine, Lopez et al., submitted 2009N

Lithology _ Landslides scars

Antoine, Lopez et al., submitted 2009

N250 mLithology _ Debris Apron

Antoine, Lopez et al., submitted 2009N

Lithology _ Dunes

Antoine, Lopez et al., submitted 2009N

Mosaic of thermal images
N• THEMIS visible
image under
infrared nightime
image

Antoine, Lopez et al., submitted 2009
Cerberus Fossae

Thermal study

Comparison between temperature and topographic profile
Thermal image of Cerberus Fossae. Temperature and topographic profiles across thefracture with dunes in the bottom.
Dashed line : temperature profile
Solid line : topographic profile

NAntoine, Lopez et al., submitted 2009
Cerberus Fossae

Thermal study

Comparison between temperature and topographic profile
Thermal image of Cerberus Fossae. Temperature and topographic profiles across thefracture without dunes in the bottom.
Dashed line : temperature profile
Solid line : topographic profile

There are no influence of the lithology on the temperature variation.
Antoine, Lopez et al., submitted 2009
Cerberus Fossae

Thermal study

Numerical model of air convection
Representationof the box
used for the airconvection
model.

Notation and values used for the model
Equations of the model:

Ra = ρa g α ΔT H K / μ κRaeq = γ Ra

Antoine, Lopez et al., submitted 2009
Cerberus Fossae

Air convection model

Model results
Plot of the observed infrared
temperature (solid line), thesurface convective temperature
for a Raeq = 45 (dotted line) andthesurface
convective
temperature for a Raeq = 1000(dashed line)

The rim crest to floor
temperature drop can beexplained
byaCO2convection for a Raeq = 45.

Antoine, Lopez et al., submitted 2009
Cerberus Fossae

Air convection model

Results

Preliminary conclusions
 Lithology, topography and surface albedo do not explain thethermal pattern, CO2 convection does explain the observed thermal behaviour :- convection permits the transport of heat through the debris apron,- for Raeq = 45, geothermal flux = 20 mW/m2, the convective temperatures fit
the observed temperatures.

 Presence of aerothermal systems on martian permeable soils.
 Others volcanic area might be possible candidates for thisconvection like the Tharsis region.

Cerberus Fossae

Contents
I/ Introduction
1) Recent finding : Aerothermal systems in terrestrial volcanic soils
Application to Mars : search for aerothermal systems in permeable soils
II/ Martian surface temperature
1) Data
2) Interpretation
III/ Part. 1: Case of Cerberus Fossae
1) Geological setting and morphology
2) Thermal study3) Modelling the aerothermal system
IV/ Part. 2: Case of Arsia Mons’ skylights
1) Geological setting and geometric characteristics
2) Thermal study3) Local and regional aerothermal systems at Arsia Mons
V/Conclusion

Arsia Mons and pits location
Lopez et al., in preparation, 2009

Context map : Location of Arsia Mons

Geographical Information System (GIS) with MOLA,HRSC and THEMIS visibles images. White cross arepits previously discovered (Cushing et al., 2007) andred cross are pits discovered during this study.
Arsia Mons’

Geological settingLocation

Pits presentation
N80 m

Three pits images extracts from HiRISE.

Bar charts of the pits size distribution
using √2D interval of pits diameters.
Lopez et al., in preparation, 2009
Arsia Mons’

Geometric characteristicDiameters

Pits presentation

Lopez et al., in preparation, 2009a)

d = - D² tan (90 - i) / 4( x0 – D/2)b)a) Schematic illustration of topographic model.
b) Application of the model in the biggest pit (i =64°).
Arsia Mons’
Geometric characteristic
DepthsMorphological values

Relation between pits and geomorphology

NLegend
Slide terrain
Collapse unit
Smooth unit
Hummocky unitAligned features
Lava channels features
Sinuous rilles
Raised ridges
Lopez et al., in preparation, 2009
Arsia Mons’

Geological setting

Morphological map madewith HRSC images.
Geomorphologic map

50 km

Relation between pits and geomorphology

N

Preferential direction NE-SW > Tharsis Montes rift zone
(extension area, Mouginis-Mark and Christensen, 2005)

Pits repartition in taking account themorphology associated at each pits.
Sinuous rilles have the most importantnumbers of pits.
Lopez et al., in preparation, 2009
Arsia Mons’

Geological setting

Geomorphologic map

50 km

Thermal study of the pitsa)b)c)

Extracts of THEMIS visible (a), infrared daytime (b) and infrared nightime (c)images (Cushing et al, 2007)
The study of the pits thermal signal is interesting because of theirtemperature. They are, in average, 10K warmer than the surroundings. Is
this observation is compatible with a CO2 convection?

Arsia Mons’

Thermal study

Thermal behaviour of Annie
Plot of the thermal pattern at different acquisition date. Rightcorner extract from a THEMIS visible image.

Lopez et al., in preparation, 2009
Arsia Mons’ slyligthsThermal study

Evolution

Thermal behaviour of Dena
Plot of the thermal pattern at different acquisition date. Rightcorner extract from a THEMIS visible image.

Lopez et al., in preparation, 2009
Arsia Mons’

Thermal study

Evolution

Influence of the geometry?

Topographic influence on cooling during night (Baratoux et al, 2005)

Case B, the cooling is less efficient during night.

Arsia Mons’

Thermal study

Geometric effectTHEMIS sub-pixels modelingb)a) HiRISE image extract of pits.
a) b) Infrared nightime image extract with the limits of hotpixels associated at pits
N80 mb)b)

Hot pixels seems to exceeds the pits entrance. To confirm this observation, athermal model tacking account sub-pixels temperature heterogeneity have beendeveloped
Lopez et al., in preparation, 2009
Arsia Mons’

Thermal study

THEMIS modelTHEMIS sub-pixels modelingT1 and T2 > pit and background temperature.
White grid > THEMIS spatial resolution. Displaced with
an offset from 0 to 1 pixel.

Blackbody law applied to each pixel with two different temperature:

Representation of the effective temperature at THEMISresolution.

Model warmer surface exceeds the pit entrance
Lopez et al., in preparation, 2009
Arsia Mons’

Thermal study

THEMIS modelResults

Observations : 17 hot pixels
Prediction assuming that the warm
surface equal that of the sky hole : 9 hot
pixel - 13 hot pixels

Lopez et al., in preparation, 2009
Arsia Mons’

Thermal study

THEMIS model

Results

Results

Observations : 11 hot pixels
Prediction assuming that the warm
surface equal that of the sky hole : 4 hot
pixel - 7 hot pixels
Comparison between model predictions
and observations confirm that the warmerarea exceeds the pit entrance. CO2
convection can explain this observation.
Lopez et al., in preparation, 2009
Arsia Mons’

Thermal study

THEMIS modelResults

Pits distribution
Compressive zone

Location of pits across the topographic profile on the South flank. Colors are theΔT between pits and surrounding.
In the compressive zone (slope break), most of the pits have a ΔT < 5K.
Lopez et al., in preparation, 2009
Arsia Mons’

Aerothermal system

Geomorphology

Thermal pattern of sinuous rilles
Thermal image of one sinuous rille located in the South flank. Temperature andtopographic profiles across the sinuous rille.
Dashed line : temperature profile
Solid line : topographic profile

Geometry of the sinuous rille> Length : 56 km, depth : 600 m, wide ≈ 965 m
Lopez et al., in preparation, 2009
Arsia Mons’

Aerothermal system

Collapse sinuous rilles

Thermal pattern of sinuous rilles
Thermal image of one sinuous rill located in the South flank. Temperature andtopographic profiles across the sinuous rille.
Dashed line : temperature profile
Solid line : topographic profile

Geometry of the sinuous rille> Length : 36.5 km, depth : 520 m, wide ≈ 3 km
Sinuous rilles have also a thermal pattern which can not be only explained bytheir shapes.
Lopez et al., in preparation, 2009
Arsia Mons’

Aerothermal system

Collapse sinuous rilles

2D Numerical model

Representation of the box used for the air convection model.

Lopez et al., in preparation, 2009
Arsia Mons’

Aerothermal system

Air convection modelPreliminary conclusions
 Pits formation : on an extensive region (rift zone), formed by theroof collapse of lava tubes.
 Temperature differences
independently of seasons

alwaysobserved

duringnight,

 Radiative effects can not explain the pits thermal pattern.
 CO2 convection is the best candidate for explaining the thermalbehaviour.
 Other arguments for this hypothesis : warm sinuous rilles andcorrelation between the pits temperature and compressive region .
 Aerothermal system at the scale of Arsia Mons can exist and could
explain the observed thermal pattern.
Arsia Mons’Conclusion
In Earth, aerothermal system was first observed in a volcanic soils
where permeability is very high. First results on Mars shows that thisaerothermal system is also possible.
N500 mIn Mars: Cerberus Fossae is a young volcanic plain where thermal pattern can be explain by a
CO2 convection. This convection is enough vigorous to transport an important amountof heat, only possible where permeability is high.
 In Arsia Mons, pits thermal behaviour :Are always observed (independently of season)
The geometric radiative effects can not explain the observations.
Pits seems to be warmer where extension is observed. It creates an area wherevertical permeability is high, making easier the exit of the warm air.
Remaining questions:- size of the convective cells (local and/or global- indirect measurement of geothermal heat flow,- search for the presence of alteration within a pit (data CRISM).

volcanoscale),Pits :Common structures on solid planets?

Pits on Earth (Mauna loa)

Pit on Moon (Haruyama et al., 2009)

Pits on Mars (Cushing et al., 2007)

Thank you for your attention