Another look at sonic thermometry

Kaimal, J. C.; Gaynor, J. E.

doi:10.1007/bf00119215

Cited by 338 publications

(186 citation statements)

References 11 publications

(12 reference statements)

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“…where v s is the speed of sound [e.g., Kaimal and Gaynor, 1991]. Sonic temperature closely approximates the virtual temperature of air, allowing the air temperature, T a , to be calculated from:…”

Section: Validation Of the Pkt Correction Proceduresmentioning

confidence: 99%

Direct measurements of the CO₂ flux over the ocean: Development of a novel method

Prytherch

Yelland

Pascal

et al. 2010

Geophysical Research Letters

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[1] Over the ocean, eddy correlation measurements of the air-sea CO 2 flux obtained with open-path sensors have typically been an order of magnitude larger than those estimated by other techniques or sensors. It is shown here that this discrepancy is due to cross sensitivity to water vapor fluctuations: a novel correction procedure is demonstrated, tested against an independent data set and proved to be robust. After correction, the observed gas transfer velocities are in reasonable agreement with published values obtained using closed-path sensors or by tracer techniques. Data from open-path sensors may now be used for air-sea CO 2 flux estimation, greatly increasing the information available on air-sea gas transfer velocity. Citation: Prytherch, J., M. J.Yelland, R. W. Pascal, B. I. Moat, I. Skjelvan, and C. C. Neill (2010), Direct measurements of the CO 2 flux over the ocean: Development of a novel method, Geophys. Res. Lett., 37, L03607,

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Section: Validation Of the Pkt Correction Proceduresmentioning

confidence: 99%

Direct measurements of the CO₂ flux over the ocean: Development of a novel method

Prytherch

Yelland

Pascal

et al. 2010

Geophysical Research Letters

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“…The sonic temperature T s is used in (5) instead of virtual potential temperature θ v , as a good approximation of virtual temperature T v (Schotanus et al, 1983;Kaimal and Gaynor, 1991), while T s is the average value at the measurement height. The term in parentheses in (6) accounts for the correction outlined in Schotanus et al (1983) for specific humidity fluctuations.…”

Section: Basic Scaling Parametersmentioning

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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“…Then R2 data were subjected to cross-wind correction according to Kaimal and Gaynor (1991). R2 was plotted against wind speed.…”

Section: Comparison Of Heat Flux Estimates Obtained With Sonic Anemommentioning

confidence: 99%

Critical re‐evaluation of the bulk transfer coefficient for sensible heat over the ocean during unstable and neutral conditions

Smedman

Erik

Johansson

2007

Quart J Royal Meteoro Soc

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ABSTRACT:A new analysis of the neutral heat transfer coefficient C HN on data fromÖstergarnsholm is presented, which is primarily based on a limited set of measurements with the very accurate MIUU (Meteorological Institute of the University of Uppsala) instrument, but with additional information from an extensive set of measurements with Solent sonic R2. Sonic data are, however, used with great caution, since for wind speed U above 10 m s −1 , a strongly windspeed-dependent correction is shown to be required. This error is roughly proportional to (U − 10) for sea-air temperature differences less than 4-5 K. For a larger temperature difference, no correction appears to be necessary in the wind speed range 10-15 m s −1 .We infer from our data that for conditions when unstable and near-neutral conditions prevail, measurements of the sea surface -air temperature difference are accurate to within 0.1 K at our site. This means that data for a range of relatively small temperature differences (0.5-1.5 K) which were often rejected in previous studies could be retained. It is observed that a rapid increase of C H and C HN occurs in that range.For wind speed above 10 m s −1 , C HN is observed to increase rapidly with U 10 . During those conditions, the wave field at the site is known to have characteristics very similar to those in deep-sea conditions. In a previous analysis of data fromÖstergarnsholm, it was speculated that observed high C HN values could be due to spray. Calculations with a spray model showed, however, conclusively that for wind speeds less than 14 m s −1 , the spray effect on the sensible heat flux is expected to be small. The high C HN values must instead be due to dynamic effects.It is demonstrated that when the Obukhov length L is less than about −150 m a regime with very specific characteristics ensues. This regime is dominated by surface-layer scale eddies, which cause Monin-Obukhov relations for the exchange of sensible heat to break down. The characteristics of this surface-layer regime are treated in detail in the companion paper.The rise of C HN with wind speed is shown to be closely related to a corresponding increase of z 0T with roughness Reynolds number for winds above 10 m s −1 . This means that during those conditions, traditional surface renewal theory for heat is no longer valid. It is suggested that this, in turn, is a result of increasing importance of wave-breaking with increasing wind and with a possible link to processes in near-surface atmospheric layers in the regime with −L > 150 m.

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Another look at sonic thermometry

Cited by 338 publications

References 11 publications

Direct measurements of the CO₂ flux over the ocean: Development of a novel method

Direct measurements of the CO₂ flux over the ocean: Development of a novel method

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

Critical re‐evaluation of the bulk transfer coefficient for sensible heat over the ocean during unstable and neutral conditions

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Another look at sonic thermometry

Cited by 338 publications

References 11 publications

Direct measurements of the CO2 flux over the ocean: Development of a novel method

Direct measurements of the CO2 flux over the ocean: Development of a novel method

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

Critical re‐evaluation of the bulk transfer coefficient for sensible heat over the ocean during unstable and neutral conditions

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Direct measurements of the CO₂ flux over the ocean: Development of a novel method

Direct measurements of the CO₂ flux over the ocean: Development of a novel method