The influence of water vapor fluctuations on turbulent fluxes

Brook, R. R.

doi:10.1007/bf00120609

Cited by 53 publications

(33 citation statements)

References 9 publications

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“…When measuring volume-related fluxes of air constituents such as water vapour, the so called WPL correction has to be applied (Webb et al 1980) in order to compensate for density fluctuations and a positive vertical mass flow. Some post-field data processing methods include the correction of Brook (1978). However, this correction should not be applied because of incorrect assumptions (Webb 1982), such as the formulation of the sensible heat flux, which lead to different opinions about which terms are negligible or not.…”

Section: Comparison Of Post-field Data Processing Methodsmentioning

confidence: 99%

The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods

Mauder

Oncley

Vogt

et al. 2006

Boundary-Layer Meteorol

197

166

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The eddy-covariance method is the primary way of measuring turbulent fluxes directly. Many investigators have found that these flux measurements oftenThe National Center for Atmospheric Research is supported by the National Science Foundation. do not satisfy a fundamental criterion-closure of the surface energy balance. This study investigates to what extent the eddy-covariance measurement technology can be made responsible for this deficiency, in particular the effects of instrumentation or of the post-field data processing. Therefore, current eddy-covariance sensors and several post-field data processing methods were compared. The differences in methodology resulted in deviations of 10% for the sensible heat flux and of 15% for the latent heat flux for an averaging time of 30 min. These disparities were mostly due to different sensor separation corrections and a linear detrending of the data. The impact of different instrumentation on the resulting heat flux estimates was significantly higher. Large deviations from the reference system of up to 50% were found for some sensor combinations. However, very good measurement quality was found for a CSAT3 sonic together with a KH20 krypton hygrometer and also for a UW sonic together with a KH20. If these systems are well calibrated and maintained, an accuracy of better than 5% can be achieved for 30-min values of sensible and latent heat flux measurements. The results from the sonic anemometers Gill Solent-HS, ATI-K, Metek USA-1, and R.M. Young 81000 showed more or less larger deviations from the reference system. The LI-COR LI-7500 open-path H 2 O/CO 2 gas analyser in the test was one of the first serial numbers of this sensor type and had technical problems regarding direct solar radiation sensitivity and signal delay. These problems are known by the manufacturer and improvements of the sensor have since been made.

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Section: Comparison Of Post-field Data Processing Methodsmentioning

confidence: 99%

The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods

Mauder

Oncley

Vogt

et al. 2006

Boundary-Layer Meteorol

197

166

View full text Add to dashboard Cite

show abstract

“…However, Brook (1978) pointed out that the fluctuation of Cp (specific heat of air) due to humidity fluctuation should be included. The sensible heat flux is equal to the enthalpy flux, and the enthalpy is defined as CpT (Huschke, 1959).…”

Section: Turbulent Fluxes and Meteorological Parametersmentioning

confidence: 99%

Surface Energy Balance Measurements around Ocean Weather Station-T during OMLET/WCRP

Tsukamoto¹,

Ishida²,

Mitsuta³

1995

Journal of the Meteorological Society of Japan

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Sea surface energy balance was analysed at the ocean weather station-T (OWS-T; 290N, 1350E), south of Japan, based on direct measurements on board. The intensive observation periods were set up during OMLET (Ocean Mixed Layer Experiment) as two cruises of the R/V Hakuhomaru, University of Tokyo around OWS-T in Apr/May 1988 and Jan/Feb 1991. The first period corresponds to the decaying stage of the ocean mixed layer and the second one is the stage of the development. Radiation measurements and turbulent flux measurements by the eddy correlation method were carried out during the cruises as well as the upper air soundings and the ocean measurements. A part of the results from OMLET'88 was already reported by Tsukamoto et al. (1990).The eddy correlation flux measurement is the most accurate one. However it is not always applicable for the sea-surface flux evaluations for a long term. The bulk aerodynamic formulas are usually accepted for practical purposes. The bulk transfer coefficient should be determined based on the eddy correlation flux measurements. However previous energy budget studies are based on universal bulk models and no confirmation was made of those results. In the present study, the bulk transfer coefficients were determined based on the eddy fluxes as a function of wind speed as in situ values. The bulk coefficients were applied to the continuous surface meteorological data for the evaluation of long-term fluxes.The net heat fluxes into the water were evaluated as +54 Wm-2 (downward) in Apr/May and -192 Wm-2 (upward) in Jan/Feb. The local time changes of the ocean mixed layer heat content were calculated with JMA buoy data as 356 Wm-2 and -297 Wm-2, respectively, The difference of these values can be regarded as due to horizontal or vertical heat transfer.

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“…However, Brook (1978) pointed that the fluctuation of Cp (specific heat of air) due to the humidity fluctuation should be included. The sensible heat flux is equal to the enthalpy flux and the enthalpy is defined as CpT (Huschke,1959).…”

Section: Turbulent Fluxes and Meteorological Parametersmentioning

confidence: 99%

Turbulent Flux Measurements and Energy Budget Analysis over the Equatorial Pacific during TOGA-COARE IOP

Tsukamoto

Ishida

1995

Journal of the Meteorological Society of Japan

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Turbulent flux measurements were carried out on board the R/V Hakuhomaru during TOGA-COARE IOP in Nov., 1992. She stayed at the station of 156E on the equator, north of the Intensive Flux Array (IFA) of COARE region for more than 2 weeks (Asai, 1993). Turbulent fluxes were evaluated by the eddy correlation method, including ship motion corrections for wind velocity fluctuations. The weather situation was relatively calm for most of the period. Convective activity developed in the latter half of the period with occasional showers. It was found that heat fluxes from the sea surface were about 14 Wm-2 and 88 Wm-2 for sensible and latent heat fluxes, respectively, as mean values of the period when Brook's correction was accepted. However they increased to almost double when a gust front developed from the precipitating cumulus as a downdraft.Bulk transfer coefficients were estimated from eddy fluxes and bulk meteorological values. The average values of CH=1.32x10-3 and CE=1.16x10-3 were evaluated. The wind speed dependencies of the coefficients were investigated and increases in the low wind speed region were observed, which supports the previous prediction. The surface energy budget was investigated based on radiation and turbulent flux measurements. The net heat flux into the water was estimated to be about 68Wm-2 in this period.The present data of eddy correlation measurements are considered to be one of the sea truth standards, as well as the ones from the R/V Moana Wave, Franklin and Natsushima.

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The influence of water vapor fluctuations on turbulent fluxes

Cited by 53 publications

References 9 publications

The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods

The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods

Surface Energy Balance Measurements around Ocean Weather Station-T during OMLET/WCRP

Turbulent Flux Measurements and Energy Budget Analysis over the Equatorial Pacific during TOGA-COARE IOP

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