Azione B3: Intercalibrazione dei due strumenti
Durata: Aprile 2013 - Dicembre 2015
Scopo: Durante questa azione i due prototipi realizzati da West Systems verranno validati tramite confornto con differenti metodologie di misura. Queste attività verranno condotte presso il Centro di Ricerca di Versailles - Grignon dell'INRA, Istituto Nazionale di Ricerca Agronomica francese. Gli obiettivi dell'attività di validazione prevedono di testare le diverse caratteristiche degli strumenti fra cui la robustezza, la sensibilità e la mobilità dello strumento trasportabile.
Partner Responsabile: INRA, Grignon - Francia 
Stato dei Lavori: L'inizio delle attività di intercalibrazione è stato posticipato a Giugno 2013 a causa di alcuni ritardi nella realizzazione della strumentazione. La valiazione dello strumento trasportabile è stata condotta a partire dalla seconda metà di giugno durante una campagna di Intercomparazione organizzata dal progetto FP7 INGOS, a Easter Bush, Edimburgo. Le attività sono state proseguite a Grignon per la prima metà di Luglio 2013. L'elaborazione dei dati è stata conclusa a Gennaio 2014, con la redazione di un Report di Validazione. La validazione della Stazione di Monitoraggio Continuo è iniziata a partire da Giugno 2014 ed è stata condotta in parallelo alle attività di monitoraggio continuo presso il CIRAA a San Piero a Grado (Pi). La cross
validation della stazione è stata conclusa con la fine dell'anno 2015, con l'emissione del report di Validazione.
Action B3: Cross Validation of the two prototypes
From April 2013 to December 2015
In this action the two prototypes developed by West Systems will be validated by means of various methodologies. This validation will be conducted at the INRA Research Centre of Versailles-Grignon (France) for about 4 months (April to July 2013). The objectives will be to test different features of the prototypes (robustness, sensitivity) and for the portable set up its operational capability in terms of mobility.
In its "portable" and "station" set-up, the prototype will be tested using different methods of flux measurements.
To validate the portable set-up we plan to use integrating methods like the micrometeorological method during few weeks. These techniques are used to determine field-scale fluxes, and include mainly eddy covariance and gradient techniques. We will use the eddy covariance methodology. It consists in measuring in a given horizontal plan the gas flow by coupling measurements of vertical wind speeds with fluctuations of N2O gas concentration with high frequency. Wind measurements will be performed with a sonic anemometer (R3-50, Gill Instruments Ltd. UK), and N2O concentrations with INRA QCL spectrometer (QC-TILDAS 76, Aerodyne, MA). During these few weeks additional measurements with a set of manual accumulation chambers will be performed, the objective being to estimate the spatial variability of N2O fluxes all around the eddy correlation tower. A set of about 15 fixed chambers will be used. N2O gas concentrations will be subsequently analyzed by INRA gas chromatography (CP-3800, Varian).
To validate the station set-up of the prototype we plan to use the INRA automatic chamber device. This device was largely used during the Nitro Europe IP program (Laville, 2011). For this device N2O gas concentrations will be measured on line by using the IR spectrometer Thermo-Scientific, model 46C. Six auto-chambers (area 0.5 m²) will be available. They are closed using electric actuator for 15 minutes each in sequence allowing a rate of 16 mean flux measurements per day for the six chambers. In this set-up the objective will be to test the robustness of the West Systems prototype, to verify if the instrument is capable of measuring over extended periods N2O flux variations and with which detection threshold and sensitivity.
Grignon site has many advantages for this cross comparison. Since 2004, Grignon was alternately site of measurements in various European programs: CarboEurope, NitroEurope and ICOS now.
Expected results
The main expected result of this action will be the cross-validation of the two prototypes, that will be considered successful if the N2O concentration deviation will be lower than 5% and the N2O flux deviation will be less than 15%. In addition, the following performances will be tested:
(1) the robustness of the two prototypes under field conditions with large climatic variations (rain, air temperatures) and dust;
(2) the air tightness of the chamber;
(3) the sensitivity and detection threshold of the two prototypes;
(4) the feasibility of moving easily and quickly for the portable prototype to evaluate N2O flux variability at field scale.
