FLUX MEASUREMENTS OF NON-CO GHGS · flux measurements of non-co 2 ghgs (instrumentintercomparisons)...

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FLUX MEASUREMENTSOF NON-CO2 GHGS

(INSTRUMENTINTERCOMPARISONS)

3RD TRAINING COURSE/WORKSHOP ONEDDYUH: A SOFTWARE FOR EDDY COVARIANCE FLUX

CALCULATIONHELSINKI 23 – 27.02.2015

O. PELTOLAUNIVERSITY OF HELSINKI, DEP. OF PHYSICS, DIVISION OF ATMOSPHERIC SCIENCES

CONTENT• BACKGROUND• INSTRUMENTATION

• Measurement principle• Available instruments• Intercomparison campaigns

• CH4• N2O

• 1960’s & 1970’s:• eddy covariance was used only for

measuring sensible heat and momentumfluxes during short campaigns

• 1980’s:• fast CO2 analysers (based on NDIR)

started to be developed• 1990’s:

• continuous EC CO2 flux measurementswere set up => FLUXNET

• 1990’s & 2000’s:• First CH4 & N2O EC studies

• 2000’s & 2010’s:• Continuous CH4 & N2O flux

measurements

BACKGROUND

http://celebrating200years.noaa.gov/foundations/weather_obs/wea01106_650.html

BACKGROUND

100150

Amount of CH4+eddy covariancepapers

Amount of CO2+eddy covariancepapers

Amount of N2O+eddy covariancepapers

• Gases absorb radiation at certain distinctfrequencies called absorption lines

• This is due to the fact that certain amount ofenergy is needed to switch into certainexited state

• Absorption depends on the gasconcentration (Beer-Lambert law):

• Measure absorption, get the concentration!0

10 lcIAI

BASICSABOUTTHEMEASUREMENTPRINCIPLE

• Atmospheric concentrations of CH4 andN2O are approximately 200 and 1000smaller than CO2Þ much more difficult to measure than CO2Þ NDIR method not applicable for CH4 and

N2O, something more accurate is needed

• Laser absorption spectrometers (LAS)measure the shape of the absorption featureaccurately• usually diode lasers working at near-IR

area are used

• Cavity ring-down spectroscopy (Picarro):• Cavity is used to enhance the signal• Concentration is determined from the

decay of signal vs time

Picarro Inc.

• Off-axis integrated cavity outputspectroscopy (Los Gatos):• Cavity is used• Integrated absorption is used

Los Gatos Research

• Tunable laser absorption spectroscopyusing quantum cascade lasers (QCL)(Aerodyne Research):• QCLs work at mid-IR area where absorption

lines are strong => better signal

Aerodyne Research

• Tunable laser absorption spectroscopyenhanced with wavelength modulationspectroscopy (Licor)• WMS is used to enhance the signal

Licor Inc.

CH4:• Los Gatos

• FMA (CH4, possibly also H2O)• FGGA (CH4, H2O, CO2)

• Picarro• G1301-f (two out of CO2, CH4, H2O)• G2311-f (CO2, CH4, H2O)

• Licor• LI-7700 (CH4, open-path)

• Aerodyne• Continuous wave QCL• Pulsed QCL

• …

AVAILABLE INSTRUMENTSN2O:

• Los Gatos• N2O, CO, H2O analyser• N2O, CH4, H2O analyser

• Aerodyne• Continuous wave QCL• Pulsed QCL

• …

INTERCOMPARISONCAMPAIGNS

- CH4:- Siikaneva- Cabauw- Other campaigns

- N2O:- Maaninka- Easter Bush

SIIKANEVA CH4INTERCOMPARISON• Campaign:

• Siikaneva oligotrophic open fen• 1.4.-25.10.2010

• Instruments:• Sonic anemometer: Metek USA-1• Methane gas analysers:

• RMT-200 (Los Gatos Research Inc.)• G1301-f (Picarro Inc.)• TGA100A (Campbell Scientific Inc.)

• Needs liquid nitrogen• Dryer

• Prototype-7700 (Li-Cor Inc.)• Open-path instrument• Low power instrument

• Results published in Biogeosciences:Peltola et al. (2013)

• Prototype-7700 housing was filledwith water after ~ 1 month• Lenses of the open cell needed

a lot of cleaning• Picarro G1301-f internal filter was

clogged mid-July• Los Gatos RMT-200 (i.e. FMA) was

working fine throughout the summer

• Cumulative emissions (NB! gapfilled):• FMA: 12.3 g(CH4) m-2

• G1301-f: 11.9 g(CH4) m-2

• TGA-100A: 11.8 g(CH4) m-2

SIIKANEVA CH4INTERCOMPARISON

• For Prototype-7700 the correctionswere on the same order of magnitudeas the measured CH4 flux• Open-path => large WPL

• For closed-path instruments thecorrections were moderate

• Agreement between RMT-200 and G1301-f is really good• TGA-100A and Prototype-7700 plots show a bit more scatter

• TGA-100A is an old instrument• Prototype-7700 is based on different design

THE CH4 INTERCOMPARISON CAMPAIGNWAS ORGANIZED WITHIN INGOS FP7INFRASTRUCTURE PROJECT

WHERE: CABAUW, THE NETHERLANDS

WHEN: 6.6.-27.6.2012

RESULTS ARE PUBLISHED INBIOGEOSCIENCES:PELTOLA ET AL. (2014)

CABAUW CH4INTERCOMPARISON

CH4CH4

WINDWIND

MEASUREMENT SETUP

VANOUR MAST

CABAUW BIG TOWER

WINDWIND

MEASUREMENT SETUP

VANOUR MAST

CABAUW BIG TOWER

INSTRUMENTS

• G2311-f (Picarro)• CH4,CO2,H2O• Sampling line:

• 30 m long• Heating

• FGGA (LGR)• CH4, CO2, H2O• Sampling line:

• 30 m long• No heating

• LI-7700 (LI-COR)• CH4• Open-path

• DLT-100 (LGR)• CH4• Benchtop FMA• Sampling line:

• LI-7500 (LI-COR)• CO2, H2O• Open-path

METEK1

All sampling tubes were made of teflon

INSTRUMENTS

• FMA1 (LGR)• CH4• Sampling line:

• 41 m long• No Heating

• FMA2 (LGR)• CH4, H2O• Sampling line:

• G1301-f (Picarro)• CH4, CO2• Sampling line:

• Pulsed QCL (Aerodyne)• CH4, N2O• Sampling line:

• 41 m long• No heating• Drier

• LI-7000 (LI-COR)• CO2, H2O• Sampling line:

METEK2

INSTRUMENTS

• FMA1 (LGR)• CH4• Sampling line:

• 41 m long• No Heating

• FMA2 (LGR)• CH4, H2O• Sampling line:

• G1301-f (Picarro)• CH4, CO2• Sampling line:

• Pulsed QCL (Aerodyne)• CH4, N2O• Sampling line:

• 41 m long• No heating• Drier

• LI-7000 (LI-COR)• CO2, H2O• Sampling line:

METEK2

In total 8 CH4 analysers:2011 G2311-f (Picarro)2010 LI-7700 (LI-COR)2009 G1301-f (Picarro)2008 FGGA (LGR)2008 FMA1 (LGR)2006 FMA2 (LGR)2005 DLT-100 (LGR)2005 pulsed QCL (Aerodyne)

G1301-f, DLT-100 and LI-7700 produced less datathan others

• G1301-f and DLT-100due to data loggingproblems

• LI-7700 duemeasurement cellcontamination

CABAUW CH4INTERCOMPARISONExample of raw data from 22/06/2012,between 10:40-11:00

Picarro instruments have lowest noise levels

LI-7700 is greatly affected by data loggingproblem

G2311-f

G1301-f FGGA

FMA FMA

DLT-100 QCL

Cumulative CH4fluxes over theperiod range from330 mg(CH4) m-2 to400 mg(CH4) m-2

Instruments with in-situ H2O agree thebest (G2311-f, FGGAand FMA2)

±10%±5%

OTHER CH4INTERCOMPARISONSIwata et al. (2014)

- rice paddy field, LI-7700 & FMA- good agreement- spectral corrections should bedone with care, also for LI-7700

LI-7700

y=0.99x, r2 = 0.93

Detto et al. (2011)- three sites- LI-7700 and FMA- WPL and spectroscopiccorrections are large for LI-7700 => inevitably affectsthe precision of the fluxestimates

SUMMARY OF CH4INTERCOMPARISONS- Generally CH4 EC analysers agree well, within 10 %- Picarro analysers show lowest noise levels

=> best analysers for locations with low CH4 fluxes- LGR analysers are rugged but need large power hungry pumps- LI-7700 is a low power instrument

=> good for remote locations- LI-7700 needs large WPL and spectroscopic corrections- Best agreement was found between closed-path analysers which measure H2O

simultaneously with CH4

MAANINKA N2OINTERCOMPARISON

Photo: Sami Haapanala

• Campaign:• Bioenergy crop plantation, Maaninka• 20.4.-21.10.2011

• Instruments:• Sonic anemometer: METEK USA-1

• TGA100A (Campbell Scientific)• Needs liquid nitrogen• dryer• CS-TDL

• CW-TILDAS-CS (Aerodyne Research)• AR-CW-QCL

• N2O/CO-23d (Los Gatos Research)• LGR-CW-QCL

• Sonic anemometer: Gill R3-50• QC-TILDAS-76-CS (Aerodyne Research)

• AR-P-QCL

Results are published in Biogeosciences:Rannik et al. (2015)

MAANINKA N2OINTERCOMPARISON

Fertilization

- Daily mean N2O fluxes were around0.1-0.2 nmol m-2 s-1

- After fertilization the fluxes were 2-8nmol m-2 s-1

- CS-TDL was measuring until end ofAugust, LGR-CW-QCL was measuringafter the beginning of Aug

MAANINKA N2OINTERCOMPARISON- White noise in the instrument signal was

estimated from the data with the methodby Lenschow et al. (2000) (lecturetomorrow!)

- CS-TDL: 1.98 ppb- AR-CW-QCL: 0.12 ppb- LGR-CW-QCL: 0.60 ppb- AR-P-QCL: 0.46 ppb

- These numbers essentially tell howprecisely the instruments can measureN2O with 10 Hz sampling frequency

MAANINKA N2OINTERCOMPARISON- The newest analysers AR-CW-QCL and

LGR-CW-QCL agree well- AR-P-QCL underestimated the fluxes

significantly during the high flux period

D. Famulari, E. Nemitz, A. Ibrom, A. Vermeulen, A. Hensen, P. Van Den Bulk, P.Laville, B. Loubet, O. Masher, M. Laborde, A. Lohila, T. Laurila,

I. Mammarella, S. Haapanala , N. Cowan, M. Anderson, C. Helfter

Nitrous oxide fluxes from a Scottish grasslandmeasured by eddy covariance: a comparison between

different systems

Zurich, 4 February 2015 daniela.famulari@gmail.com

EASTER BUSH N2OINTERCOMPARISON

- Campaign:- Intensively managed grassland,

Edinburgh, UK- 3.6.2013-30.6.2013- Organised within InGOS FP7

infrastructure project- Instruments:

- 2 x Gill HS-50- CEH cw-QCL (AR-CW-QCL)- INRA cw-QCL (AR-CW-QCL)- DTU LGR (LGR-CW-QCL)- FMI LGR (LGR-CW-QCL)

- dryer!- UHEL LGR (LGR-CW-QCL)- ECN QCL (AR-P-QCL)

Results from Famulari et al. (in prep)

172170168166164Day of the year

Fertilisation LGR FMI QCL CEH LGR UHEL p-QCL ECN LGR DTU QCL INRA

- N2O fluxes were around 0.5-5 nmol m-2 s-1

- AR-P-QCL shows erratic behavior, otherwise instruments agree

- Noise values are similar to Maaninkaintercomparison Results from Famulari et al. (in prep)

0.1 1 10 100Integration Time (s)

370.5N2O

18:0024/06/2013

18:10 18:20 18:30

s [ppt]0.1 s 207.08189.0 s 13.25900 s 101.96

Instrument 0.1s

best 15min

ECN QCL 767 213 636 137CEH cw-QCL

200 19 38 20

INRA cw-QCL

207 13 102 23

DTU LGR 540 32 256 56FMI LGR 1046 27 194 91UHEL LGR 621 40 172 81

86420-2AVERAGE FLUX

1:1offset = 2.5e-5slope = 0.98r2 = 0.97

H86420-2

AVERAGE FLUX

offset = -8.9e-6slope = 1.03r2 = 0.99

86420-2AVERAGE FLUX

1:1offset = 3.3e-5slope = 1.05r2 = 0.95

86420-2AVERAGE FLUX

1:1offset = -4.5e-4slope = 1.06

86420-2AVERAGE FLUX

1:1offset = -7e-5slope = 1.06r2 = 0.89

86420-2AVERAGE FLUX

1:1offset = -3.1e-5slope = 0.98r2 = 0.94

Results fromFamulari et al.(in prep)

SUMMARY OF N2OINTERCOMPARISONS

- Generally N2O analysers agree within 10 % (not in Maaninka)- Using dryer vs not using did not seem make much difference

- The new Aerodyne laser was most precise- Best for low flux conditions

- Traditionally N2O fluxes have been measured only at agriculturalareas where fluxes are high

- With the latest generation lasers, it is possible to measure verysmall fluxes, potential for non-agricultural fluxes and uptakestudies

- Huge development has been made during the last decade in non-CO2 GHGinstrumentation

- The new analysers are more rugged and better suited for field conditions- Flux measurements can be conducted in places which were previously unavailable

(power restrictions, too low fluxes)- Bright future for non-CO2 GHG flux measurements!

SUMMARY

THANKS!

Photo taken by SamiHaapanala

FLUX MEASUREMENTS OF NON-CO GHGS · flux measurements of non-co 2 ghgs (instrumentintercomparisons)...

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