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Mars Express «atmospheric sciences »
Inputs for TGO…
François FORGET
Mars Express Interdisciplinary Scientist
IPSL Laboratoire de Météorologie Dynamique
CNRS, Paris, France
+ the Mars Express teams !
Outline
• Introduction to Mars Express
• Mars meteorology– Temperatures– Surface pressure– Dust and clouds
• Water vapor
• Other Trace gases
Mars Express Orbiter
• 7 main Instruments :
• HRSC (camera) : visible
• OMEGA (imaging Vis and NIR spectrometer) : 0.3-5.2 µm
• PFS (NIR and thermal spectrometer): SWC:1.2-5.8 µm + LWC 6-50 µm
• SPICAM (UV and NIR atmospheric spectrometer): 0.1-0.31 µm + 1-1.7 µm
• ASPERA (Energetic Neutral Atoms Imager
• MaRS: Radio Science Experiment
• Marsis : Radar
Eccentric Orbit + Pericenter latitude drift
Pericenter latitude = f(t)
10/01/04
30/05/04
Sun elevation
i < 0°
0 < i < 15°
15° < i <30°
I > 30°
orbit 10000 upcoming this year- Mission extension confirmed for 2011+2012 - and adopted for 2013+2014, pending mid-term confirmation.
Thermal structure in the lower atmosphere with PFS
spectral resolution 1.8 cm-1
PFS
TES
Zasova et al.
PFS obs
GCM model
Morning Evening
Thermal structure below 50 km : LMD GCM prediction with Mars Express PFS (Giuranna et al. 2007)
60 km
40 km
20 km
60 km
40 km
20 km
Ls = 50°-70° (N. spring)
PFS aerosol thermal infared observations
Silicate dust
Water ice clouds of different kinds-polar hood-topographic clouds -equatorial cloud belt-morning haze -night fog in Hellas-clouds above the melting polar cap.
One Lesson from Mars Express: Meteorology data from PFS (T(z), dust, clouds) could have been shared as well as possible and as early as possible with the other instruments team to help data processing
Role of MCS on TGO
MaRS : radio sciences(Pätzold et al. Tellmann et al.)
• uses the Radio Subsystem (High Gain Antenna) of Mars Express• no Ultrastable Oscillator (only ingress)But: higher sensitivity of measurement in Twoway
• coherent downlink at two frequencies: X-Band (8.4 GHz) S-Band (2.3 GHz)
MaRS : radio sciencesComparison with MGS
0 90 180 270 360
Solar Longitude [deg]
-90
-60
-30
0
30
60
90L
atit
ud
e [d
eg
]MaRSMGSOCC 10
Solar Longitude (Pätzold et al. Tellmann et al.)
Comparison with MGS
0 6 12 18 24
Local Time [hours]
-90
-60
-30
0
30
60
90
La
titu
de
[d
eg
]
MaRSMGSOCC 10
Local TimeLocal Time
(Pätzold et al. Tellmann et al.)
• Upper atmosphere temperature with SPICAM stellar occultations (60-130 km) [Forget et al. 2009]
Density to Temperature profiles
CO2 density Temperature
Ls = 11°, 16.8°N
Spectra
Slant densities
Montmessin et al. 2011
Surface pressure retrievals with OMEGA at 2 µm
Principle of the pressure retrieval
CO2 absorption
at 2 microns
Retrieval: Least-square fitting w/ synthetic spectra from line-by-line radiative transfer
Inputs 1. Observation geometry e,i,φ2. Atmospheric state T, τ3. Surface properties 4. Surface pressure
Features• Dust absorption / simple
scattering scheme• Multidimensional look-up
tables
Forget et al. 2007
Seasonal CO2 cycle monitored by OMEGA
Forget et al. 2007
Surface pressure oscillations
Very flat topography
Spiga et al. 2007
Relative error on a given pressure measurement
–Temperature–Dust opacity–Pyroxenes
–Instrumental noise
Forget et al. 2007
Total relative error: Monte-Carlo random exploration
1-sigma relative error of- 7 Pa for A_L=0.29- 10 Pa for A_L=0.2- 15 Pa for A_L=0.15
OMEGA instrumental standard deviation was evaluated to 1.3 Pa
Forget et al. 2007
Forget et al. 2007
Observation of aerosol at solar wavelengths
• OMEGA : – Nadir : not easy by several methods (Maatanen et al. 2010,
Vincendon et al. 2007,2011 : dust brighter than expected; Doute et al. 2011 use effect on CO2 2µm band at high airmass)
– Limb observations: very promising, but not yet fully analysed (Fouchet et al. 2006, Vincendon et al. 2011 more soon).
• SPICAM: UV : – limb observations (Rannou et al. 2006)– Stellar occultation (Montmessin et al., 2006)– Solar occultation (Listowski, 2011)
• SPICAM NIR : solar occultations– Fedorova et al. (2010)
27
surface reflectance is 0
at λ = 2.64 µm
refle
ctan
ce f
acto
r
CO2 ice
wavelength (µm)
sun
Dust at the south pole
Vincendon et al. 2007,2009
282004 / 2005 2006 / 2007
Spatial variations of the dust optical depth
Vincendon et al. 2009
Observation of aerosol at solar wavelengths
• OMEGA : – Nadir : not easy by several methods (Maatanen et al. 2010,
Vincendon et al. 2007,2011 : dust brighter than expected; Doute et al. 2011 use effect on CO2 2µm band at high airmass)
– Limb observations: very promising, but not yet fully analysed (Fouchet et al. 2006, more soon).
• SPICAM: UV : – limb observations (Rannou et al. 2006)
– Stellar occultation (Montmessin et al., 2006)
– Solar occultation (Listowski, 2011)
• SPICAM NIR : solar occultations– Fedorova et al. (2010)
Fedorova et al. (2010)
Simultaneous observations of H2O, CO2 and aerosols
• 1) H2O density from 1.38 m band• 2) Atmospheric density from 1.43 m CO2
band • 3) Aerosol extinction profiles and particle
size distribution with 10 spectral points outside gaseous absorption bands
CO2
H2O
Spectral range: 1-1.7 µm
Spectral power:Spectral resolution
R~20000.5-1.2 nm
FOV nadir occultation
1° ~0.07° (3.5 km at 3000 km to limb)
Aerosol points: dashed lines
SPICAM IR – AOTF spectrometer:
Cause: mis-pointing of the real optical axis wrt predicted oneSolution: find the altitude shift that gives the best agreement between observed and modeled CO2 profileMethod: weighted mean altitude difference of the profile NOTE: recently studied by Scanning the solar disk in two orthogonal planes with constant θ/φ coordinates wrt. spacecraft body frame
etc...
<Δh> = 14.64 km
Problem with solar occultation – Pointing
Maltagliatti et al.
Sun occultation examples of spectra
• A principle of sequential scanning of a spectrum: short windows and dots
• Two detectors
• The record of a spectrum takes 4-6 seconds
• Vertical resolution is 3.7 km with distance to limb 3000 km
• A new optimal command for SPICAM IR permitting simultaneous observations of CO2, H2O and aerosol vertical distributions with spectral dependence of aerosol extinction in solar occultation mode was adapted only in April 2006
4 sec4 sec
6 sec
4 sec
Fedorova et al. (2010)
Vertical distribution of reffRed line is the H2O refractive index, blue line is the ‘Marsdust’ model
High-altitude cloud with reff=0.1-0.3 m
Northern hemisphere
Reff ~0.4-0.8 m assuming a dust
Reff ~0.4-1.2 m assuming H2O
The size gradient has been observed
Southern hemisphere
Fedorova et al. (2010)
Particle size variationswith season and latitude
reff, m
Fedorova et al. (2010)
Observation of water ice clouds at solar wavelengths
• SPICAM UV : Mateshvili et al. (2007)• OMEGA NIR : Madeleine et al. (2011): Mars
water ice clouds opacity and particle size
• LIMB observations
36
37
A difficult retrieval using two observations with and without clouds (Madeleine et al. 2011)
Mars water ice clouds opacity and particle size using OMEGA (Madeleine et al., submitted to JGR)
• CO2 ice clouds
Detection of high altitude CO2 ice clouds with OMEGA (Montmessin et al. 2007)
Opacity > 0.2Altitude ~80 km
Reff up to 1.5 m
First spectroscopic identification by Mars First spectroscopic identification by Mars Express (PFS, OMEGA, Formisano et al. 2006, Express (PFS, OMEGA, Formisano et al. 2006, Montmessin et al. 2007)Montmessin et al. 2007) Observations by MOC & TES (Clancy et al. Observations by MOC & TES (Clancy et al. 2007), SPICAM (Montmessin et al. 2006), VMC, 2007), SPICAM (Montmessin et al. 2006), VMC, THEMIS (McConnochie et al.)THEMIS (McConnochie et al.)
CO2condensation
SPICAM stellar occultationForget et al. 2009
Detached aerosol layer simultaneously in the stellar occultation Montmessin et al., Icarus 2006CO2
condensation
Seasonal evolution mapSeasonal evolution map
HRSC
OMEGA
(spicam)
Mars Express H2O measurements
• PFS spectral resolution 1.4 cm-1
– LW 25-35 µm: processed by 2 groups: Fouchet et al., Icarus 2007– SW 2.56 µm: processed by 3 groups: Tschimmel et al., Icarus 2008.
• OMEGA 2.56 µm mapping processed by 2 groups– Encrenaz et al. A&A 2005, 2008– Melchiorri et al. PSS 2007, Icarus 2009– Maltagliati et al., 2008; 2009 in press?
• SPICAM 1.37 µm spectral resolution 3.5 cm-1 processed by one group– Fedorova et al., JGR 2006
Compared to Mars Global Surveyor TES• TES 25-50 µm, spectral resolution 6.25 or 12.5 cm-1
Korablev et al. 2009
On the difficulty of measuring water vapor : comparison of Mars Express H2O measurements
SPICAM
PFS LW
OMEGA
PFS SW
Korablev et al., ISSI group
usuallyPFS LW ≤ SPICAM ≤ OMEGA ≤ TES ≤ PFS SW
Side effects of Mars Express water vapour comparisons
• TES/MGS database modification– Bug in processing low resolution (12.5 cm-1)
portion of data
– Reduction of H2O content in this data by 30%
• MAWD/Viking dataset modification– Reprocessing of MAWD with new
spectroscopic database (HITRAN 2004)– Reduction of the entire dataset by 60%
Korablev et al., ISSI group
Solar occultation water vapor retrieval (Maltagliatti et al. : in revision for Science)
Solar occultation water vapor retrieval (Maltagliatti et al. : in revision for Science)
— Observation— Model fit
Solar occultation water vapor retrieval (Maltagliatti et al. : in revision for Science)
— Observation
— LMD GCM
Solar occultation water vapor retrieval (Maltagliatti et al. : in revision for Science)
Trace Gas Observations
– Ozone– O2 – NO– CO– SO2 ?– H2O2 ?– Methane
Trace Gas Observations
– Ozone• Spicam NADIR• Spicam stellar occultation
Typical duration of obs. 30 min
Frequency of records 1 spectrum/sec
Integration time 450 ms
Field of view at pericenter ~ 2 km
CO2 O3 dustcloudssurface
SPICAMobservations in nadir mode110-320 nm Ozone
Mapping with Spicam
SPICAM raw spectra SPICAM geometrylon(t), lat(t), HL(t), Ls, SZA(t), (t)(t)
Mars Climate Databasesurface pressure, T profile, O3 profile
Radiative Transfer Model
SHDOM210-300 nm0-60 km 12 layers
Optimal Parameters• ozone column• albedo at 210 nm• albedo at 300 nm• dust opacity
Correction of dark current and stray light
Averaging over 50 s(250 spectra)
Division by Data Reference Spectrum
Olympus Mons Ls =170° (Orbit 1448)
Spectral smoothing(5 nm)
Levenberg-Marquardt fit4 free parameters: • ozone column• albedo at 210 nm• albedo at 300 nm• dust opacity
262A01Ls = 13.3
lat = 35°
lat = 70°
lat = 50°
lat = 60°
SPICAM Ozone Column
polar night
polar night
spring
spring
summer
summer
autumn
autumn
winter
winter
Perrier et al., J. Geophys. Res., 2006
Analysis of SPICAM ozone columns with the LMD GCM
GCM ozone column (micron-atmosphere)
Lefèvre et al., Nature, 2008
70N-90N
50N-70N
winter
wintersummer
summer
Model Ozone column
wintersummer
O3 profile using SPICAM UV stellar occultation(Lebonnois et al. 2007)Comparison with GCM
Trace Gas Observations
– O2 • O2 florescence (1.27µm) resulting from dayside:
– OMEGA nadir and Limb : Altieri et al. 2009;
– SPICAM NIR Nadir and Limb Guslyakova et al. 2011;
– PFS Geminale et al. 2011
• O2 Recombination Nightglow Emission at 1.27 µm – OMEGA/MEX: Bertaux et al. 2011
– SPICAM Guslyakova et al. 2011 )
Gravity waves on polar regionsas observed by OMEGA with O2 emission
Southern late winter/early spring MY28
Northern late winter MY26
Apparent MR
Apparent MR
Altieri et al. 2009
Altieri et al. 2009
Carbon Monoxide
• OMEGA (resolution Encrenaz et al. (2006) – CO main line :(2–0) at 2.35 µm
• PFS
– CO main line :(2–0) band centered at 4255 cm−1 (around 2.35 μm) difficult to use because of affected by mechanical vibrations
– Billebaud et al. (2009) Billebaud et al. 4.7 μm spectra of Mars ((1–0) ro-vibrationnal)
– Sindoni et al. PSS 2011: Measuring CO at 4235cm1 (2.36 µm) branch of (2–0) band
CO mixing ratio Sindoni et al. PSS 20114235cm1 (2.36 µm)
CO enrichment in Hellas: predicted by GCM, detected by OMEGA (Encrenaz et al. 2006)
CO main line :(2–0) at 2.35 µm
GCM : % of non condensible gaz
OMEGA observations:
HELLAS
HELLAS
Trace Gas Observations
– Ozone– O2 – CO– NO– SO2 : search in the UV with SPICAM UV nadir
observations (Marcq et al. 2011)– H2O2 : search in the thermal IR using PFS with line
at 362 cm-1 (+ 379, 416 and 433 cm-1). So far inconsistent results (Kasaba, Aoki et al. 2010)
– Methane
Methane (PFS: 3018 cm-1)• Very difficult detection by Formisano et al. (Science 2004)
• Further results by the PFS team published recently – A. Geminale, V. Formisano, M. Giuranna. Methane in Martian
atmosphere: Average spatial, diurnal,and seasonal behaviour Planetary and Space Science 56 1194–1203(2008)
– Geminale, Sindony, Formisano: Mapping methane in Martian atmosphere with PFS-MEX data Planetary and Space Science 59 137–148 (2011)
Enigmatic variability,
patchy behaviour
Geminale et al. 2008
Geminale et al. 2011
• Thank you
