m. ghysels 1 , j. cousin 1 , n. amarouche 3 , l. gomez-martin 1 , e. d. riviere 1 , g. durry 1,2

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.

21/04/23 1

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

21/04/23 M. GHYSELS, GSMA 2

+ 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


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


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


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


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


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


PicoSDLA-CH4 sensor

Laser head

Germanium filter

Detector

Gold coating retroreflector


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), 89-1000.

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


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


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


Signature of overshoots ?

13th March 2012

PicoSDLA-CO2


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


•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


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


m. ghysels 1 , j. cousin 1 , n. amarouche 3 , l. gomez-martin 1 , e. d. riviere 1 , g. durry 1,2

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