Quantifying trace gas emissions and the influence of surface exchange processes on the atmosphere is a necessary step towards the control of global greenhouse gas emissions and reliability of air quality models. This paper proposes a procedure based on the mass balance method and implemented on highly resolved aircraft data. It allows one to estimate surface exchanges on areas of several km2 and heterogeneous features exploiting the characteristics of convective boundary layer during steady state conditions that permit the estimation of emission/absorption terms as functions of advective fluxes only. A nonparametric approach is adopted and the fluxes on the surface of a virtual box surrounding the area of interest are reconstructed on the basis of scalar densities and wind vectors using Shepard functions. Two different techniques are also proposed to face lack of data on the top surface of the box. The method has been applied to experimental data coming from measurement campaigns on two different sites. It provides realistic estimates of the CO2 emission/absorption in the considered areas that are in good agreement with CO2 fluxes evaluated by Airborne Eddy Covariance and confirm the suitability of the proposed approach for the assessment of turbulent exchange of trace gases by composite landscapes. Uncertainties on the estimated emissions due to both propagation of the experimental error and interpolation have been quantified by bootstrap analysis as 6%.

Quantifying trace gas emissions and the influence of surface exchange processes on the atmosphere is a necessary step towards the control of global greenhouse gas emissions. Also air quality models require highly resolved emission data. This paper propose a procedure based on the mass balance method and implemented on highly resolved aircraft data, which allows us to estimate surface exchanges on areas of several km 2 and heterogeneous surface features. We adopt a nonparametric approach and reconstruct the fluxes on the surface of a virtual box surrounding the area of interest using Shepard functions. Two different techniques are also proposed to face lack of data on the top surface of the box. The method is applied to the experimental data from a measurement campaign in Eboli to obtain an evaluation of the CO2 emission/absorption in the area.

Uno degli interventi proposti dal protocollo di Kyoto per la stabilizzazione delle concentrazionidi gas serra si riferisce alla necessità di determinare la localizzazione delle sorgenti e delle fonti ditali gas. Il metodo del bilancio di massa, implementato a partire da misure rilevate da piattaforma aerea,presenta la potenzialità di poter quantificare gli scambi gassosi superficiali su aree di diversi chilometriquadrati, permettendo una stima anche in condizioni di eterogeneità superficiale, contrariamente ai metoditradizionali. In questo studio il metodo è stato applicato ad un sito nei pressi di Forlì utilizzando dati telerilevatiad alta frequenza nello strato limite planetario. La scarsa risoluzione verticale ottenuta in fase dirilevamento dati è stata risolta attraverso un metodo di regressione non parametrico. I campi di concentrazionedel gas e del vento in corrispondenza dell'altezza dello strato limite planetario sono determinaticon un modello additivo non parametrico. Risulta che la superficie del territorio esaminato emette un flussodi anidride carbonica di 13±0.3 ?moli/m2/s, a causa della presenza di un centro industriale all'internodell'area esaminata.