A picture of QCLAS (July 2011).
QCLAS optical schematic.
QCLAS thermalization (P1, P2, P3, P4 are plates filled with water dispatched from the chiller).
Example of signals recorded by QCLAS: (a) a N2O absorption spectrum; (b) the Fabry Perot signal.
(a) N2O recorded signal and its baseline, (b) N2O calculated transmission and his fitted line, (c) residuals which are the difference between the calculated transmission and the fitted line.
Automatic control system for successive measurements with different calibrated N2O bottles.
Measurement protocol of the second data sets.
(a) Calculated N2O concentrations, (b) temperature in degree Celsius (°C), (c) pressure in millibar (mbar).
Calculated N2O concentrations of calibrated bottles and calibrated values (in solid lines): (a) all data, (b) averages on each bottle in each cycle (a point in (b) is the average of the concentration values corresponding to a given bottle), (c) difference between averages in (b) and the real calibrated values.
Principle of flux measurement.
A picture taken in Wallis and Futuna Island during the field campaign.
Temperatures (a) and pressures (b) of a recorded flux measurement.
(a) N2O and CH4 recorded signal and the baseline, (b) Fabry Perot signal, (c) N2O and CH4 calculated transmission and the fitted line, (d) residuals which are the difference between the calculated transmission and his fitted line.
N2O and CH4 concentrations and fluxes for two different measurement sites: (a) in an area close to a manure site featuring much stronger emission fluxes. The fluxes values are estimated from a linear regression over the concentration data; (b) in an area not impacted by pig farming.
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