Transcript of 11 Collisional effects on spectral shapes and remote sensing H. Tran LISA, CNRS UMR 7583,...
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- 11 Collisional effects on spectral shapes and remote sensing H.
Tran LISA, CNRS UMR 7583, Universit Paris-Est Crteil and Universit
Paris Diderot HiResMIR@CAES-Frejus-2013
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- 22 Outline Introduction: Atmospheric observation and spectral
shape Isolated line : - The Doppler, Lorentzian and Voigt profiles
- Limits of the Voigt profile - Laboratory studies - Influence on
atmospheric retrieval Line-mixing for closely spaced lines -
Line-mixing effects - Laboratory studies - Influence on
spectroscopic data extraction - Influence on atmospheric retrieval
Conclusions HiResMIR@CAES-Frejus-2013
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- 33 Measured spectra (satellite, balloon, ground,) - P, T
profiles - Molecule mole fraction profiles - Cloud altitude,
aerosol - etc. Input spectroscopic data (Position, Intensity,
spectral shape,) Spectral shapes Collisional (pressure) effects on
the spectral shape Radiative transfer Forward model Introduction:
Atmospheric retrievals HiResMIR@CAES-Frejus-2013
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- 44 Pressure DopplerDoppler+CollisionCollisions
GaussienVoigtLorentzian Comparaison between the Gaussian, the
Lorentz and the Voigt profiles. Introduction: The Voigt profile
HiResMIR@CAES-Frejus-2013
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- 55 Bernath et al., GRL, 32, L15S01 (2005) ACE spectra at
different tangent altitudes (1-0) R(0) 3 R(9) Introduction:
isolated lines and closely spaced lines
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- 66 Isolated lines HiResMIR@CAES-Frejus-2013
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- 77 Measured and adjusted spectra using the Voigt profile. H 2
O/N 2, 3 band, 11 1,11 10 1,10 11 0,11 10 0,10 Limits of the Voigt
profile HiResMIR@CAES-Frejus-2013
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- 88 Limits of the Voigt profile HiResMIR@CAES-Frejus-2013 It
neglects: 1.The velocity changes induced by collisions. The
detailed balance: change from v to v v. reduction of the Doppler
broadening Dicke narrowing effect 2.The speed-dependences of the
collisional width (v) and shift (v) of the line. This also (in
general) leads to a narrowed line
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- 99 - For the velocity changes effect: The Galatry (soft
collisions) and Rautian (hard collisions) line-shapes. Introducing
a parameter VC (or ) - the velocity changing collisions frequency.
- For the speed dependences of the line-width and shift: The
speed-dependent Voigt profile, assuming a simple quadratic
dependence on the absolute speed or polynomial dependence on the
relative speed Simple and widely used non-Voigt approaches
HiResMIR@CAES-Frejus-2013
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- 10 In situ absorption spectrum of tropospheric H 2 O recorded
by balloonborne diode laser and its fits using the Voit profile and
the Hard Collision profile Durry et al, JQSRT 94, 387,2005
Influence of non-Voigt effects on atmospheric retrievals
HiResMIR@CAES-Frejus-2013
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- 11 Barret et al, JQSRT 95, 499, 2005 HF profile retrieved from
ground-based absorption FTIR measurements (Jungfraujoch station) in
the (1-0) R(1) micro-window by using the Voigt profile and the Soft
Collision model, compared with the HALOE profiles smoothed.
Influence of non-Voigt effects on atmospheric retrievals
HiResMIR@CAES-Frejus-2013
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- 12 (Diode laser) Measured absorption of pure H 2 O (left) and H
2 O in air (right) and their differences with those adjusted using
the VP, HC, and SDVP HC Influence of non-Voigt effects on line
parameters determination HiResMIR@CAES-Frejus-2013
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- 13 Ratios of the self-broadening coefficients and intensity
obtained by the HC (o) and SDVP ( ) to those obtained by the VP,
for 13 H 2 O lines in the near-infrared. Influence of non-Voigt
effect on line parameters HiResMIR@CAES-Frejus-2013
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- 14 VC rate in red (SC) Rohart et al, J Mol Spectrosc 251, 282,
2008 Dependence of VC on pressure Relaxation of the 317.2 GHz line
of O 3 in collision with O 2 at 240 K. Remaining problems with
these non-Voigt approaches HiResMIR@CAES-Frejus-2013 Need to take
into account both Dicke and speed dependence effects
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- 15 2 limits Hard collision model Soft collision model : memory
parameter KS more realistic than these two extreme cases and more
suitable for intermediate cases Velocity changing by the Keilson
and Storer model HiResMIR@CAES-Frejus-2013
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- 16 With the model we compute the line shape. Then we fit the
calculated spectra (as the measured ones) by Voigt profiles and
look at the residuals. Pure H 2 O, 296K, 2 1 + 2 + 3 band:
measured, calculated 6 06 7 07 5 15 4 14 Model-experiment
comparison : pure H 2 O HiResMIR@CAES-Frejus-2013
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- 17 H 2 O/N 2, 296K, 3, 11 111 10 110, 11 011 10 010 doublet H 2
O/air, 296K, 2 1 + 2 + 3, 5 15 4 14 line measured, calculated
Model-experiment comparison: H 2 O/air
HiResMIR@CAES-Frejus-2013
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- 18 Model-experiment comparison: H 2 /N 2 Collisional width 296
K, Q(1) m = 0.92, 0 = 0.41 Bonamy et al., Eur. Phys. J. D, 2004 995
K, Q(1) m = 0.95, 0 = 0.50 HiResMIR@CAES-Frejus-2013
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- 19 Non-isolated transitions: Line-mixing effects
HiResMIR@CAES-Frejus-2013
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- 20 In some cases, for closely spaced lines, the Voigt profile
fails when P increases. It predicts shapes that are too broad.
Collisions induce transfers of populations between the levels of
the two lines that lead to transfers of intensity between the
lines. Line-mixing effects HiResMIR@CAES-Frejus-2013
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- 21 Line-mixing effects: Absorption coefficient k populations d
k matrix element of radiation-matter coupling tensor L 0 matrix of
positions W relaxation operator. All effects of collisions.
Independent of within the impact approximation (not too far in the
wings) W lk 0 Line coupling between |k> and |l> W lk =0 No
line coupling (Lorentz ) HiResMIR@CAES-Frejus-2013
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- 22 For moderate line overlapping, a first order perturbation
approach is possible. Then we only need to know one coupling
parameter (Y, related to the W matrix elements) per line
Line-mixing effects: Relaxation matrix HiResMIR@CAES-Frejus-2013
Relations for W
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- 23 HiResMIR@CAES-Frejus-2013 Nadir looking instruments onboard
satellites Greenhouse gases Observation SATellite (GOSAT,
JAXA-NIES, in orbit) Orbiting Carbon Observatory (OCO 2, NASA)
MicroCarb (CNES, under study), CarbonSat (ESA, under study)
Spectral regions and aims - CO 2 from 1.6 m (weak) and 2.1 m
(strong) bands - Air mass from O 2 A band (0.76 m) - CH 4 from 2 3
band (near 1.7 m) - aerosols from CO 2 and O 2 bands
Detection/quantifying sinks and sources (1 ppm for x CO2, 0.3 %)
Extreme accuracy of spectra modelling. Huge constraints on the
spectroscopic data and the prediction of pressure effects
(collisions and spectral-shape) Line-mixing and remote sensing:
Monitoring GreenHouse Gases from space
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- 24 Sza 79.9, Park Falls, region 2.1 m Wrong air-mass (and time)
dependences CO 2 retrieved Sza 79.9, Park Falls, region 1.6 m CO 2
: ground-based measurements HiResMIR@CAES-Frejus-2013
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- 25 Sza 79.9, Park Falls, 1.27 m band Sza 79.9, Park Falls, A
band Wrong time (and air-mass) dependences O 2 : Ground-based
measurements HiResMIR@CAES-Frejus-2013
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- 26 Spectra: air mass 5.7, Park Falls Wrong time and airmass
dependences Largely erroneous conclusions on sinks and sources CH 4
: Ground-based atmospheric solar absorption
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- 27 No use CO 2 bands: Scaling model, self consistent model for
all bands. Adjustment of model in 720 cm -1 Q branch. No use of
present NIR bands CH 4 : Semi-classical model. Self consistent
model for 3, 4 and 2 3 bands. Adjustment of model in 3 band at high
pressure. No use of present 2 3 band No use O 2 A-band: Scaling
model. Model developed from O 2 A band at elevated pressure. No use
of low pressure spectra Collision induced absorption: From analysis
of O 2 A band at elevated pressures Modeling of line-mixing effect
HiResMIR@CAES-Frejus-2013
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- 28 O 2 /N 2 A band 76.0 atm 47.6 atm 28.1 atm ___ measurement,
___ Line-mixing ___ Lorentz CO 2 /N 2 Line-mixing effects:
Laboratory studies HiResMIR@CAES-Frejus-2013
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- 29 Line-mixing effects: Influence on spectroscopic parameters
retrieval CH 4 /N 2, 2 3, R(6), 296 K
HiResMIR@CAES-Frejus-2013
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- 30 12990130201305013080131101314013170 -0.05 0.00 0.05 0.10
0.15 observed-(LM+CIA) Residual wavenumber (cm ) -0.05 0.00 0.05
0.10 0.15 observed-Voigt 0.0 0.2 0.4 0.6 0.8 1.0 Transmission
Influence on retrievals: O 2 ground-based measurements
HiResMIR@CAES-Frejus-2013 Spectra: Sza 79.9, Park Falls O 2 A band
region O 2 A band: Relative errors on surface pressures retrieved
from atmospheric spectra
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- 31 Fits of a ground based transmission spectra in the region of
the 2 1 + 3 band of CO 2 Significant errors (10%) on the CO 2
atmospheric amount. Sinks and sources !!! Influence on retrievals:
CO 2 ground-based measurements HiResMIR@CAES-Frejus-2013
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- 32 Influence on retrievals: CH 4 ground-based measurements
Methane amounts retrieved from atmospheric spectra
HiResMIR@CAES-Frejus-2013
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- 33 Jupiter ISO/SWS spectrum in the 4 band region of CH 4
Influence on planetary spectra HiResMIR@CAES-Frejus-2013
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- 34 Summary Spectral shape has become a key issue for high
precision soundings (OCO, ACE, ) When line is isolated: - The Voigt
profile fails to model isolated line-shape -> need to take into
account Dicke narrowing and speed dependence effects (velocity
effects) - Influence of velocity effects on atmospheric retrieval
is quite small (but few studies available) When lines are closely
spaced (especially at high pressure): - line-mixing can be observed
- Increasing evidences of influence of line-mixing for remote
sensing - Need to take into account both line-mixing and velocity
effects HiResMIR@CAES-Frejus-2013
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- 35 -General Equations -Isolated Lines -Line-mixing -Far wings
-Collision Induced processes -Consequences for applications
-Remaining problems HiResMIR@CAES-Frejus-2013