Come varia nel tempo l'angolo associato alla terza rotazione (McMillen, 1988)

In Giugno 2019 è uscito il primo articolo scientifico dedicato ai dati della campagna di misura MetAlp presso l’Alpe Veglia. In particolare si studiano i dati ad alta frequenza, acquisiti con l’anemometro sonico, nei primi due mesi di misura (27 settembre, 16 novembre 2018). Con l’articolo intitolato “An Assessment of Coordinate Rotation Methods in Sonic Anemometer Measurements of Turbulent Fluxes over Complex Mountainous Terrain” si vuole, grazie ai dati della stazione, indagare come i diversi metodi di analisi del dato di turbolenza possano influire sulla loro qualità, e quale sia il metodo che introduce l’errore più piccolo.

L'articolo

An Assessment of Coordinate Rotation Methods in Sonic Anemometer Measurements of Turbulent Fluxes over Complex Mountainous Terrain

Autori: Alessio Golzio, Irene Maria Bollati, Silvia Ferrarese

Abstract

The measurement of turbulent fluxes in the atmospheric boundary layer is usually performed using fast anemometers and the Eddy Covariance technique. This method has been applied here and investigated in a complex mountainous terrain. A field campaign has recently been conducted at Alpe Veglia (the Central-Western Italian Alps, 1746 m a.s.l.) where both standard and micrometeorological data were collected. The measured values obtained from an ultrasonic anemometer were analysed using a filtering procedure and three different coordinate rotation procedures: Double (DR), Triple Rotation (TR) and Planar Fit (PF) on moving temporal windows of 30 and 60 min. A quality assessment was performed on the sensible heat and momentum fluxes and the results show that the measured turbulent fluxes at Alpe Veglia were of a medium-high quality level and rarely passed the stationary flow test. A comparison of the three coordinate procedures, using quality assessment and sensible heat flux standard deviations, revealed that DR and TR were comparable, with significant differences, mainly under low-wind conditions. The PF method failed to satisfy the physical requirement for the multiple planarity of the flow, due to the complexity of the mountainous terrain.

L'andamento delle variabili meteorologiche durante i primi due mesi di campagna.

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