A study of the assessment of air temperature, and sensible-and latent-heat fluxes from sonic-anemometer observations

Cassardo, Claudio; Sacchetti, D.; Morselli, M. G.; Anfossi, D.; Basso, Giuseppe; Longhetto, A.

doi:10.1007/bf02511367

Cited by 20 publications

(13 citation statements)

References 15 publications

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“…Two example of the difference between the "sonic" sensible heat flux (w T s ) and the actual sensible heat flux (w T ) related to field experiments can be found in [14] and [12]. The first work shows a general validity of the approximation (Equation 6) with a prevail of the first term on the right-hand side.…”

Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 96%

“…Hence, sonic anemometers can be considered instruments suitable for direct measurements of momentum and heat fluxes, due to their high-frequency acquisition rate (around 20 Hz). Latent heat fluxes can also be measured, coupling the anemometer with other fast response instruments ( [2,12]). Besides measuring the three components of the air wind vector, the sonic anemometer evaluates the sound speed c, which depends on the thermodynamic properties of the propagation fluid, according to the expression:…”

Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 99%

“…The first work shows a general validity of the approximation (Equation 6) with a prevail of the first term on the right-hand side. In some circumstances however the difference may be relevant and the direct sonic measurement can only give an idea of the order of magnitude of w T [12]. To evaluate the fluxes, an additional issue must be taken into account because the presence of a slope surface may distort the vertical flux propagation.…”

Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 99%

See 2 more Smart Citations

Preliminary Results on the Evaluation of Factors Influencing Evapotranspiration Processes in Vineyards

Francone

Cassardo

Spanna

et al. 2010

Water

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The paper summarizes the preliminary results from the analysis of data collected during the 2008 and 2009 vegetative seasons in a northern Italy vineyard (Vitis vinifera L., Barbera variety) and the simulations carried out in the same period with the land surface model UTOPIA. The aim of the work is to study the influence of the meteorological factors on the plant conditions. We collected a set of standard and advanced meteorological, physiological and physical data and we investigated the performance of UTOPIA in describing the different components of the energy and hydrological processes (in particular the evapotranspiration), with a special focus on the vegetation and soil. The comparison between observed data and UTOPIA simulations showed satisfactory results for the soil variables (RRMSE ranging between 15% and 40%, and correlation coefficients of 0.9). Net radiation and sensible heat fluxes RRMSE (30% and 63% respectively) suggest that both Water 2010, 2 917 the calibration of the vegetation parameters (including the influence of the grass among vine rows) and the availability of more specific measurements are very important.

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Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 96%

Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 99%

Section: Sonic Anemometer and Flux Measurementsmentioning

confidence: 99%

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Preliminary Results on the Evaluation of Factors Influencing Evapotranspiration Processes in Vineyards

Francone

Cassardo

Spanna

et al. 2010

Water

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“…As in that paper, the full data record was broken into 1-hour segments each containing 72,000 raw data of wind (u, v, w) and temperature (T) observations. The hourly wind data were first rotated with reference to a streamline system (McMillen, 1988;Cassardo et al, 1995). The linear trend was then removed from each series using the least squares method (Bendat and Piersol, 1971), noting the well-known fact that such a trend will be manifest in the spectrum as significant low frequency energy (Hanna, 1983).…”

Section: Tisby Datasetmentioning

confidence: 99%

An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

Anfossi

Oettl

Degrazia

et al. 2005

Boundary-Layer Meteorology

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169

184

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When the wind speed decreases below a certain value (1-2 m s À1 ) meandering (low frequency horizontal wind oscillations) starts to prevail. In these conditions it becomes difficult to define a precise mean wind direction and to estimate the airborne dispersion. To study the wind and turbulence characteristics during meandering, two sonic anemometer datasets, containing hourly wind observations, were analysed: the first one, lasting 1 year, was recorded in complex terrain (Graz, Austria) and the second one, lasting about 1 month, was recorded in a rather flat area (Tisby, Sweden). It was found that meandering seems to exist under all meteorological conditions regardless of the stability or wind speed and it was confirmed that meandering sets a lower limit for the horizontal wind component variances. Further, it was found that the autocorrelation functions of the horizontal wind components, computed for the low wind cases, show an oscillating behaviour with the presence of large negative lobes. Two different relationships from the literature, and relevant to these oscillatory aspects, were fitted to the data. They contain two parameters: one associated and relevant to the classical integral time scale and the second with meandering occurrence. Based on these relationships, expressions for the mean square displacement of particles r 2 y ðtÞ were also derived.

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“…One of the procedures most frequently adopted in the analysis of surface layer turbulence measurements, especially when dealing with flows over complex terrain, is the so called streamwise alignment (McM; Kaimal and Finnigan, 1994;Cassardo et al, 1995;Wilczak et al, 2001). This procedure takes into account only the dominant wind direction, but also compensates possible sensor misalignments from a reference system with vertical axis along the local gravity.…”

Section: Streamwise Alignmentmentioning

confidence: 99%

Analysis of second‐order moments in surface layer turbulence in an Alpine valley

Franceschi

Zardi

Tagliazucca

et al. 2009

Quart J Royal Meteoro Soc

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ABSTRACT:The paper presents the analysis of field measurements in the atmospheric surface layer over the floor of the Adige Valley, near the city of Bolzano in the Alps. Turbulence quantities, such as drag coefficient, displacement height and roughness length, appear similar to those reported in the literature concerning surface-layer turbulence over flat uniform terrain. The analysis of the non-dimensional standard deviations (σ u , σ v , σ w ) legitimates the adoption, for all the wind components, of the same Monin-Obukhov similarity relationship in the form σ i /u * = α i (1 + β i |ζ |) 1/3 , originally proposed only for flat uniform terrain under steady state conditions, and the extension of this expression to the case of winds over a valley floor in slowly varying situations. The coefficients α i are very similar for along-valley and cross-valley winds, as are the β i ones. Moreover the α u values are only slightly larger than the α v , contrary to what is reported in the literature. Conversely, σ θ /θ * shows distinctly different behaviour in the stable and unstable regimes. In particular, in the latter case a large scatter in the data is observed. However, since the most scattered data turn out to occur in transition periods (i.e. sunrise and sunset), after a specific data selection the best-fit parameters are more accurately estimated. In addition, emphasis is laid on the relevance of an appropriate formulation and use of a suitable recursive filter to separate the low-frequency unsteadiness of the mean flow from the turbulence signal.

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A study of the assessment of air temperature, and sensible-and latent-heat fluxes from sonic-anemometer observations

Cited by 20 publications

References 15 publications

Preliminary Results on the Evaluation of Factors Influencing Evapotranspiration Processes in Vineyards

Preliminary Results on the Evaluation of Factors Influencing Evapotranspiration Processes in Vineyards

An Analysis Of Sonic Anemometer Observations In Low Wind Speed Conditions

Analysis of second‐order moments in surface layer turbulence in an Alpine valley

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