Investigation of Martian water vapor with PFSSW

1
Investigation of Martian water vapor with PFS/SW

• M. Tschimmel, D.V. Titov, N.I. Ignatiev,
• E. Lellouch, T. Fouchet, M. Giuranna, V.
  Formisano

Mars Water Cycle Workshop, Paris - 21.04.2008
2
Outline

• The retrieval technique for PFS/SW
• Results
• Seasonal and spatial behavior of water vapor on
  Mars
• Comparison with PFS/LW
• Future work
• Conclusions

3
H2O retrieval procedure (2.6 µm band)

• preparation of the measured PFS spectrum
• averaging of 15 apodised PFS/SW spectra
• adjustment of the wavenumber grid
• normalization of the averaged PFS spectrum with
  piecewise function
• temperature pressure profiles from EMCD 4.1
  model
• within the fitting loop
• fast calculation of the monochromatic
  transmittances based on precalculated look-up
  tables of absorption coefficients
• convolution with the PFS spectral response
  solar spectrum
• normalization of the synthetic spectrum
• iteration over fH2O to find the mixing ratio
  with the
• best fit between 3820 cm-1 and 3900 cm-1
• account for water absorption in selected
  continuum points
• PFS continuum adjustment and iteration of the
  fitting loop
• saturation level included, but dust not included

4
result of the fitting loop
synthetic spectrum
PFS spectrum
solar spectrum
5
Results
6
seasonal development in MY 26/27
spring
summer autumn
7
seasonal development in MY 26/27
summer

autumn
8
Net water transport ?!
90 N - 60 N
60 N - 30 N
30 N - 0 N
no data
bad data
9
H2O column density map (orbits in summer)
10
H2O column density map (all orbits)
Arabia Terra
11
orbit 348 comparison of different results
LS26
saturation level
12
orbit 1023 comparison of different results
LS111
saturation level
13
orbit 1023 H2O confinement to 2.5 km
LS111
14
Ratio of SW/LW results vs. season
15
Future work much more data!
edge of the seasonal cap
MY 28
16
Conclusions I

• H2O average 10 - 15 pr.µm
• northern summer maximum ( 65 pr.µm)
• 1) peak 75N latitude
• 2) longitudinally inhomogeneous
• 3) weak latitudinal southward transport ( 25
  )
• Arabia Terra clearly above average ( factor 2)
• ? interaction with the surface

17
Conclusions II

• within uncertainties (20 30 ) agreement
  between different H2O-on-Mars teams
• indication of water confinement to the boundary
  layer, especially for the northern summer at high
  latitudes
• Northern maximum 5 ( 300 km) south of seasonal
  cap edge
• Strong interaction with the soil

18
extra slides
19
typical SW spectrum (averaged)
contamination
H2O
2.6 µm
S/C vibration
CO2
20
first normalization of the measured spectrum
PFS normalized spectrum
continuum
averaged PFS spectrum
21
adjustment of the PFS continuum for H2O absorption
PFS normalized spectrum
continuum (adjusted)
averaged PFS spectrum
22
Mars Odyssey neutron map


23
Orbit 278 comparison of different results
LS16
24
Orbit 278 H2O confinement to 2.5 km
LS16