m. ghysels 1 , j. cousin 1 , n. amarouche 3 , l. gomez-martin 1 , e. d. riviere 1 , g. durry 1,2
DESCRIPTION
Development of PicoSDLA laser sensors for in-situ measurements of CH 4 , CO 2 and H 2 O in the UTLS in the frame of the TRO-pico project. M. GHYSELS 1 , J. COUSIN 1 , N. AMAROUCHE 3 , L. GOMEZ-MARTIN 1 , E. D. RIVIERE 1 , G. DURRY 1,2. - PowerPoint PPT PresentationTRANSCRIPT
Development of PicoSDLA laser sensors for in-situ measurements of CH4,
CO2 and H2O in the UTLS in the frame of the TRO-pico project.
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M. GHYSELS1, J. COUSIN1, N. AMAROUCHE3, L. GOMEZ-MARTIN1, E. D. RIVIERE1, G. DURRY1,2
1 Groupe de Spectrométrie Moléculaire et Atmosphérique, GSMA, UMR CNRS 7331UFR Sciences Exactes et Naturelles, BP 1039, 51687 REIMS Cedex 22 IPSL, Laboratoire Atmosphères, Milieux, Observations Spatiales, UMR CNRS 8190, 78280 Guyancourt, France3 Division technique de l'Institut National des Sciences de l'Univers, 1, place Aristide Briand, 92195, Meudon Cedex, France.
Scientific context
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+ 150%
Sources of methane:
• Anthropogenic : Fossils fuels production, rice cultivation, biomass burning, waste management, etc…
• Natural : Wetland, non-wetland soil, gas hydrates, premafrost, termites, oceans, etc…
More than 50% of methane emission come from human-related activitiesOn per molecule basis, 25 times more efficient radiatively than CO2 molecule
Water vapor and methane in the stratosphere
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In the tropics : Deep convection permits injection of species in the stratosphere by overshooting convection or slow ascent in the TTL
Oxidation of CH4 in stratosphere:
CH4 + OH CH3 + H2O
Methane in stratosphere: source of water vapor
Winter at poles: In the stratosphere, PSC formation → Ozone depletion
O3 depletion during winter 2011
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TRO-Pico balloon campaign (PI. E. D. Rivière, GSMA)Main Objective : Characterization of overshoots in order to quantify their impact on the hydratation of low stratosphere (regional → global scale)
•Cirrus formation, impact of electrically charged particules on TTL
•Validation of satellites measurements of water vapour of IASI/Metop and SAPHIR/Megha-tropiques
•Variability of low stratosphere humidity : regular sounding of water vapourLaunchs from Bauru (Brazil, 22°S) Collaboration: l’IPMet-UNESP
Development of PicoSDLA-CH4 : scientific objectives
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PicoSDLA-CH4 :
• Precision <5%
• Measurement time reduced:
10 ms to 1 s (measurement under parachutes, speed ≈ 15 m.s-1)
• Regular soundings under small meteorological balloons PicoSDLA-CH4
optical path lenght : 3.6 m
SDLA spectrometer, optical path lenght : 56m
PicoSDLA-CH4 ~15 kg : L= 3.6 m
SDLA [Durry and G. Megie, (1999)] Total weight ~80 kg, L = 56m
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Based on direct absorption spectroscopy :
Laser Détector
F0 F
40
CHatmosatmosatmosmol NLPTTSF
FA ),,()()(
Determination of mixing ratio from Beer-Lambert law : (low absorption hypothesis)
S(Tatmos) : Line strenght [cm-1/molec cm-2]φ(Tatmos, Patmos, σ) : Line profileL : Optical path lenght [cm]NCH4 : Number of molecules
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Novawave Technologies (Dr. J. JOST), Inc. (USA) 20 cm x 12 cm x 2.5 cm, 980g
CDFG Laser module
Laser head
Optical fiber
Output power ≈ 10µW
Continuous coverage: 3076 to 3096 cm-1
DFG laser source → access to the R(6) transition of the ν3 band of CH4 (3086 cm-1, 3.24 µm)
Strong fundamental band → Reduction of optical path lenght: 56m → 3.6 m
In laboratory, determination of spectroscopic parameter (uncertainty <2%)
Pump diode
Signal diode
PPLN crystal
1.5 µm
1 µm
3.24 µm
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PicoSDLA-CH4 sensor
Laser head
Germanium filter
Detector
Gold coating retroreflector
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2 balloon campaigns:
• ENRICHED, Kiruna 2011. Successfull test flight the 1st of April inside the polar vortex
M. Ghysels et al, Ap. Phys. B,104, Issue 4 (2011), Page 989-1000.
ComparisonTWIN/ PicoSDLA → good agreement
PicoSDLA-CH4 onboard TWIN(PI A. Engels, University of Frankfurt)
LOD 2. 10-4
Precision : 5% at 20km
Kiruna
1. 10-3
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TRO-Pico Bauru (Brazil, 22°S) 1 scientific flight 14th of March 2012
PicoSDLA-CH4 before flight (Bauru, 2012)
3085,8 3085,9 3086,0 3086,1 3086,2
0,992
0,994
0,996
0,998
1,000
Tra
ns
mis
sio
n
Wavenumber (cm-1)
Observed Calculated
CH4, R(6) manifold, ν3 band, Alt: 22.6 km
ρCH4 = 1.42 ± 0.05 ppmv
Preliminary results :
1,4 1,5 1,6 1,7 1,8 1,91000
100
-80 -60 -40 -20 0 20
Pre
ssu
re (
mb
ar)
Mixing ratio (ppmv)
Pico-SDLA CH4 ascent
Pre
ssu
re (
mb
ar)
Temperature (°C)
Temperature
PicoSDLA-CH4 flight14th of March 2012 (Bauru)
Sensor PicoSDLA-H2O
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PicoSDLA-H2O , Bauru 2012
1m
Date of the flight Remarks
9th of March Need more work for data process
11th of March Successfull, overshooting?
13th of March Sucessfull, convective conditions during the flight. Need more analysis
TRO-Pico : 3 flights (march 2012)ENRICHED (2011): comparison with ELHYSA (PI. G. Berthet, LPC2E, Orléans)
→ good agreement
1 m path lenght, 10kg weight
1E-6 1E-5200180160
140
120
100
80
60
40
-80 -70 -60 -50 -40 -30
Pre
ss
ure
(m
ba
r)
Mixing ratio
11th of March
13th of March
Temperature (°C)
Preliminary results
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Signature of overshoots ?
13th March 2012
PicoSDLA-CO2
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Calibration in laboratory:
• Long time measurements (4h) from calibrated mixing of carbon dioxide and dry air
• Allan variance : τAllan = 980 s, σ Allan = 280 ppbv
Precision ≈ 1ppmv for 1s averaging time
Calibrated value : 503.9 ppmvCalculated value : (502.6 ± 2.2) ppmv
4h
PicoSDLA-CO2 flights
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•ENRICHED balloon campaign from Kiruna (67°N) : 1 flight the12th of March 2011
•Shortly : TRO-Pico balloon campaign from Bauru (22°S), 2 flights
Objective : Lack of observations of the CO2 concentration’s decrease throught the UTLS [S. Park et al. (2010)]
About ≈ 10 ppmv (mid-latitudes)
Conclusion
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TRO-Pico :PicoSDLA-CH4 : 1 flights and 1 future flight (Jan-Feb of 2013).PicoSDLA-H2O : 3 flights, 2 flights in convective conditionsfuture: 15 background flights and 4 convective flightsPicoSDLA-CO2: 2 flights (in convective conditions)
ENRICHED : Intercomparison TWIN/ PicoSDLA-CH4 → good agreementIntensities (uncertainty <2%), γself determined Actually, temperature dependance of γair
Validation of PicoSDLA-H2O by intercomparison ELHYSA/PicoSDLATest flight of PicoSDLA-CO2
Thank you for attention
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