Water vapor line parameters: Some feedback from atmospheric users

S. Fally http://www.ulb.ac.be/cpm

A. C. Vandaele http://aeronomie.be

S. Trabelsi, E. Mahieu, P. Demoulin http://girpas.astro.ulg.ac.be

C. Frankenberg http://www.sron.nl

H. Vogelmann, T. Trickl http://imk-ifu.fzk.de

ASA2008 1 Outline

gb-FTIR @ Junfraujoch, Swiss Alps

Discrepancies between ≠ H2O µwindows

Near-IR DIAL @ Zugspitze, Germany

HITRAN compared to Ponsardin & Browell

Near-IR SCIAMACHY /

Effect of H2O parameters on CH4 retrievals

IR SOIR /

Spectroscopic needs for CO2 broadened H2O

ASA2008 2 gb-FTIR @ Jungfraujoch, Swiss Alps (46.5°N, 8°E, 3580 m a.s.l.)

ASA2008 3 gb-FTIR @ Jungfraujoch …

-1 Numerous wv lines in the 700-4300 cm range

Best retrieval strategy to retrieve H2O vertical information? Find suitable lines in ≠ spectral domains (T° insensitive, free of interferences, ...) Lot of µwindows investigated

Spectral domain Nb H2O lines Selected µw -1 16 (cm ) (mainly H2 O) 700 - 1300 2130 16 1900 - 2200 1236 8 2500 - 3100 2348 10 3100 - 3500 2727 17 4000 - 4300 1837 12

ASA2008 4 gb-FTIR @ Jungfraujoch …

vertical sensitivity ?

3 Info close to the ground in the wings of strong line

3 Info at high altitude at the center of weak & strong lines (but strong is saturated)

Combination of µwindows including strong & weak lines

Matrix of the contribution functions for O3 profile inversion (from B. Barret, PhD thesis, 2003)

ASA2008 5 gb-FTIR @ Jungfraujoch … Multi-µwindows fits:

824.74 Wavenb (cm-1) 825.45 841.60 Wavenb (cm-1) 842.20

924.42 Wavenb (cm-1) 925.63 954.95 Wavenb (cm-1) 955.85 Poor quality (poorer than with single µwindow) HITRAN line parameters must be modified Tuned line parameters have been adopted Detailed results: See poster 2-3 by P. Demoulin et al.

ASA2008 Inconsistencies between different regions 6 Outline

gb-FTIR @ Jungfraujoch, Swiss Alps

Discrepancies between ≠ H2O µwindows

Near-IR DIAL @ Zugspitze, Germany

HITRAN compared to Ponsardin & Browell

Near-IR SCIAMACHY / ENVISAT

Effect of H2O parameters on CH4 retrievals

IR SOIR / Venus Express

Spectroscopic needs for CO2 broadened H2O

ASA2008 7 Near-IR DIAL @ Zugspitze, Germany (47.42 °N, 10.98 °E)

Zugspitze Summit 2964 m FTIR, GPS, in-situ Schneefernerhaus 2675 m LIDAR

Garmisch-Partenkirchen 734 m FTIR, GPS, in-situ

ASA2008 8 Near-IR DIAL @ Zugspitze … Optimum line choice ? 935nm, 3 Simulations of the LIDAR performance Mid-lat in 3 spectral regions: 725, 817, 935 winter, dry -1 935nm, nm (13800, 12200, 10700 cm ) Mid-lat summer, dry using mid-lat summer & winter H2O 817nm, profiles (LOWTRAN5 model) Mid-lat 3 Error analysis: summer 817nm, Minimize error at high altitude Mid-lat winter # Abs. cross-section = strong enough to get significant light loss = weak enough to avoid too much attenuation at low alt. # Error next to the tropopause < 5% Both criteria# met by the 817 nm range Altitudinal profile of the relative meas. error (noise neglected) (from Vogelmann

ASA2008 & Trickl, Appl. Optics47, 2116-2132, 2008)9 Near-IR DIAL @ Zugspitze … Chosen lines

-1 λon = 817.223nm = 12236.6 cm winter (dry) -1 λon = 817.162nm = 12237.5 cm summer -1 λon = 816.757nm = 12243.5 cm summer (not shown) -1 λoff = 817.351nm = 12235.0 cm (from http://gap-vm-pub1.gap.fzk.de/305.php) Exp. details in Vogelmann & Trickl, Appl. Opt., 47, 2116-2132, 2008 ASA2008 10 Near-IR DIAL @ Zugspitze …

Dataset choice for line parameters ? 3 Comparison of strengths for 1 line @ 12236.56 cm-1

4.5E-23 Sche rmaul '01 (RAL) # HITRAN= Ponsa rdin Tolchenov '08 & B rowell '97 (RAL reanalysed) Toth’94 Flaud et al Tolchenov et al '97 4.0E-23 '03 (RAL HIT RAN '00 reanalysed) + update'01 HITRAN '04 Mérienne '0 3 # Tolchenov’08 + update'06 (from HITRA N) (from Toth94) ≈ Ponsardin & ] 2 3.5E-23 Browell’97 ec cm l o m

-1 m

[c # ICLAS y t i s n

e 3.0E-23 (Mazzotti’06): t In only weak lines (≤ 5e-26)

2.5E-23 Tolchenov et al # TDLS '02 (f rom RAL) (Ibrahim’08): 4.12 3.97 3.69 3.70 3.72 4.33 2.17 3.84 4.15 2.0E-23 Not reported 3 Toth & Mérienne / Ponsardin: Avg 7 lines around 12200cm-1 = 0.897 & 0.899 (±0.015 & 0.011) ~ 10% systematic diff. (although high internal precision) linked to meas. technique & lineshape ? Inconsistencies between different databases ASA2008 11 Near-IR DIAL @ Zugspitze … Dataset choice for line parameters? 3 Comparison between lab. FTS & simulated spectra GaP diode Si diode Si diode InSb MCT Xe arc lamp Xe arc lamp W lamp W lamp W lamp 0.020

ν 5ν 7ν 2ν+δ ν+δ

δ ) 4ν+δ 0.018 s

7ν+δ 6ν+δ it 5ν+δ n

)

s

t

i n 0.016

u

. u . 8ν 6ν

b

r b a 2ν FTIR spe (600m, 0.4 torr, 291K)

(

y

t

i 4ν ar

s ( n 0.014 Flaud97

e t 3ν

n y

I

it Hitran06 3ν+δ 0.012 Ponsardin97 ens t

n Tolchenov02 I 0.010 26000 24000 22000 20000 18000 16000 14000 12000 10000 8000 6000 4000 2000 Tolchenov08 Wavenumber (cm-1) 0.008

0.0010 Stronger line @ 0.0005 12236.5 simulates 0.0000 worse than the 2 -0.0005 weaker ones -0.0010 HITRAN = 12236.5 12237.5 12238.0 12238.5 best results Wavenumber (cm-1) Others (exc. Tolch02)= similar results (with peak err~10%) Inconsistencies both within each database (strong>

gb-FTIR @ Jungfraujoch, Swiss Alps

Discrepancies between ≠ H2O µwindows

Near-IR DIAL @ Zugspitze, Germany

HITRAN compared to Ponsardin & Browell

Near-IR SCIAMACHY / ENVISAT

Effect of H2O parameters on CH4 retrievals

IR SOIR / Venus Express

Spectroscopic needs for CO2 broadened H2O

ASA2008 13 SCIAMACHY / ENVISAT

ASA2008 14 SCIAMACHY / ENVISAT…

SCIAMACHY / ENVISAT : 3 8 channel grating spectrometer 3 UV VIS IR (240-2380 nm) 3 http://envisat.esa.int/instruments/sciamachy/

CH4 retrievals : 3 Nadir spectra -1 3 1630-1670 nm (5990-6130 cm ) Interfering spe= CO2 & H2O 3 See Frankenberg et al.,ACP, 2005; JGR, 2006; ACPD, 2008

Context : 3 Unresolved seasonal bias in the SH

Impact of wv spectroscopy on CH4 retrievals ? 3 See Frankenberg et al., GRL35, L15811, 2008 (Aug. 12)

ASA2008 15 SCIAMACHY / ENVISAT… Comparison of HITRAN & BR (Bxl-Reims) databases

Retrievals from 2 g-b high resolution FTIR solar absorption spectra (Paramaribo, Suriname & Bremen, Germany) (from Frankenberg et al., GRL35, 2008) Systematic residuals with HITRAN mostly vanish with modified BR = up to 6% @ Paramaribo; < @ Bremen due to < wv Very strong residuals for few strong lines with BR, esp. 5975-5998 cm-1 -1 (γair<< or unprovided) + same for 4200-4350cm Proposed modifications to BR list Overall, substantial reduction of systematic errors with BR as

ASA2008compared to HITRAN 16 SCIAMACHY / ENVISAT…

Impact of wv spectroscopy on SCIAMACHY CH4 retrievals

3 Retrieved CH4 vs total wv column over Sahara:

# Exclude latitudinal bias # Exclude true correlation

CH4 emissions/specific humidity

+ correlation if HITRAN

No correlation if modified BR list

Retrieval bias caused by erroneous wv HITRAN database ASA2008 17 SCIAMACHY / ENVISAT…

Impact of wv spectroscopy on SCIAMACHY CH4 retrievals 3 BR – HITRAN for column yearly averaged mixing ratio:

(from Frankenberg et al., GRL35, 2008) up to -60ppb in the tropics = 3% overestimation with HITRAN over tropics

Significant -& surprisingly big !- impact of wv on CH4 retrievals in the 5990-6150 cm-1 range ASA2008 18 Outline

gb-FTIR @ Jungfraujoch, Swiss Alps

Discrepancies between ≠ H2O µwindows

Near-IR DIAL @ Zugspitze, Germany

HITRAN compared to Ponsardin & Browell

Near-IR SCIAMACHY / ENVISAT

Effect of H2O parameters on CH4 retrievals

IR SOIR / Venus Express

Spectroscopic needs for H2O

ASA2008 19 SOIR / Venus Express

ASA2008 20 SOIR / Venus Express …

SPICAV = Spectroscopy for Investigation of Characteristics of the Atmosphere of Venus = 3 UV-IR spectrometers ground H corona (> 40000km alt) = SPICAV-UV (SUV), SPICAV-IR (SIR), SOIR (Solar Occultat° at )

Key questions: 3 Why such a ≠ evolution compared to Earth ?

3 High D/H (150 x terresrial) dramatic H2O escape

Which scenario? Dry from the beginning OR H2O lost? New measurements are necessary

SOIR: simult. meas. H2O & HDO H2O, HDO, H/D vertical profiles retrievals

Best candidates: -1 3 H2O 3830 cm ν1 & ν3 fund. bands 70-110 km 3 HDO 2715 cm-1 ν1 fund. band 70- 95 km

More info: 3 Friday talk by A. C. Vandaele

3 H2O, HDO, CO2: Fedorova et al., JGR, in press, 2008

3 CO, CO2, HCl, HF: Vandaele et al., JGR, in press, 2008 3 Venus Express: http://sci.esa.int & http://www.venus.wisc.edu

ASA2008 21 SOIR / Venus Express …

H2OHDO Order 171 Order 121 1 1

0.8 0.8

0.6 0.6 ance ance t t i i ansm 0.4 ansm 0.4 Tr Tr

0.2 0.2

0 0 3825 3830 3835 3840 3845 3850 2705 2710 2715 2720 2725 Wavenumber [cm-1] Wavenumber [cm-1]

Evolution of 1 occultation at sunset Aug. 20th 2007:

Transmittance spectra in specific ranges of H2O (left) & HDO (right) absorptions (from Vandaele et al., 2008)

ASA2008 22 SOIR / Venus Express … H2O

HDO

Examples of best fit on July 27th 2007 (from Fedorova et al., 2008) = chosen region because lines=higher intensity, lower sensitivity

to T°, poor CO2 contamination Broader lines in the model: # uncertainties in the T° profile # instrument function width & resolut° # lineshape

ASA2008 23 SOIR / Venus Express …

Literature data for γCO2 ?

3 Howard et al., J.Opt.Soc.Am, ’56 γCO2/γair= 1.3

3 Gamache et al., JMS, ’95 1.0-2.5µm γCO2/γair= 1.3 2.0

3 Brown et al., JMS, ’07 5.0-7.7µm γCO2/γair= 1.67(.95 3.07)

NO experimental / calculated values in our region

Chosen value: γair(HITRAN) x 1.7

BUT accurate γCO2 needed to reduce uncertainties

-1 γCO2 for wv 2.3-4.2 µm (2250-4360 cm ) required

ASA2008 24 ’’Spectroscopic’’ conclusions

H2O spectroscopic problems Improvements Needs 3 Discrepancies between µwindows in HITRAN for 700-4300 cm-1 (FTS spectra @ Jungfraujoch) Tuned HITRAN line parameters proposed More consistent parameters 3 Discrepancies between literature data @ ~12300 cm-1 (DIAL measurements @ Zugspitze) More consistent parameters

3 Inaccuracies in wv parameters for 5990-6130 cm-1

(CH4 retrievals with SCIAMACHY) BR list better than HITRAN + update for spurious lines proposed

-1 3 No γCO2 in 2250-4360 cm (SOIR/SPICAV/VENUS Express)

γCO2

ASA2008 25 General conclusions

Importance of : - inter-comparisons, cross-validations - feedback from users - close collaborations between experimentalists & atmospherists - new dedicated measurements

Importance of high quality water spectroscopy & lab-work, both for wv retrieval itself & for other species

ASA2008 26 Acknowledgments Colleagues 3 A. C. Vandaele & SPICAV/SOIR team, 3 S. Trabelsi, E. Mahieu, P. Demoulin, 3 C. Frankenberg, 3 H. Vogelmann, T. Trickl

Funding Belgian Federal Science Policy Office (SSD program/AGACC project, ESA-PRODEX program/C90268, C90113, C17645 contracts) European Space Agency ESA (ESA-PRODEX program) National Fund for Scientific Research, Belgium (FRFC program) Communauté Française de Belgique (Actions de Recherche Concertées) GAW-CH Programme, MeteoSwiss, Zurich

Thank YOU for …21 your attention ! ☺

ASA2008 27