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Protocol for Picarro

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Protocol for filling liquid nitrogen 

Be aware that the tanks of liquid nitrogen are continuously leaking in small amount. Therefore DO NOT take the elevator with these containers. Use the stairs while the tanks is taking the lift.

Protocol for microbalance

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Memory reduction 

Memory between liquid injections is one of the prime concerns with spectroscopic water isotope measurements. Liquid remaining in the measurement system on tubing walls, filters and other parts is removed over several injections, increasing time demand, cost and reducing precision. We explore and evaluate different methods to reduce memory, by modifying the sample precision software, injections methods, coating of parts of the analyser and accessories. Results are continuously made available to the public in a FARLAB report series.

Vapour calibration 

Raw vapour measurements are first corrected for humidity dependency using an isotope-dependent humidity dependency correction developed at FARLAB (Weng and Sodemann, in prep.). Calibration of vapour data is based on the recommendations by the IAEA (2009). Standards bracketing a measurement period (typically 24h) are identified and quality-checked. Calibration interpolates then linearly in time between both standard measurements. Data are archived in a netCDF data format, including metadata on sampling and calibration procedures. 

Weng, Y. and Sodemann H., in prep: Correction of water concentration and isotope ratio dependence in water vapour isotope measurements with CDRS instrumentation. 

IAEA (2009): Reference Sheet for VSMOW2 and SLAP2 international measurement standards. Issued 2009-02-13, International Atomic Energy Agency, Vienna, 5 p. 

Liquid calibration with FLIIMP 

Calibration of liquid measurements is performed following recommendations by the IAEA (2009). The calibration procedure, including selection of samples and control of instrument parameters has been implemented into a processing package named FLIIMP (FARLAB Liquid Isotope Measurement Processor). FLIIMP reports raw and calibrated data in HTML format and data tables in CSV format for further processing. FLIIMP will be made available on the FARLAB website as open-access software after completed quality check procedures. 

IAEA (2009): Reference Sheet for VSMOW2 and SLAP2 international measurement standards. Issued 2009-02-13, International Atomic Energy Agency, Vienna, 5 p.