Momentum and heat fluxes via the eddy correlation method on the R/V <i>L'Atalante</i> and an ASIS buoy

Pedreros, Rodrigo; Dardier, G.; Dupuis, Hélène; Graber, Hans C.; Drennan, William M.; Weill, Alain; Guérin, C.; Nacass, P.

doi:10.1029/2002jc001449

Cited by 41 publications

(40 citation statements)

References 34 publications

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“…As a very rough estimate, the bulk transfer coefficient of CE = 1.2×10 3 corresponds to the eddy covariance latent heat flux. According to the previous studies of CE based on the eddy-covariance measurements (e.g., Pedreros et al 2003), the value ranged between 1.1 1.2×10 3 and the present preliminary result is almost consistent with them. The transfer coefficient can be variable with the wind speed or atmospheric stability, however, the dependency was not observed in the present data.…”

Section: Quality Controlsupporting

confidence: 79%

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On-board Automated Eddy Flux Measurement System over Open Ocean

Takahashi

Kondo

Tsukamoto

et al. 2005

SOLA

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On-board direct eddy flux measurement is essential in the quantitative air-sea flux evaluation as sea truth flux. Present authors have developed a new real-time automated eddy flux system and it is operating as a routine measurement on R/V MIRAI, JAMSTEC. As compared to our previous system, ship motion correction scheme is simplified and real-time eddy flux data processing system is introduced as the automated system. As a continuously operating real time eddy flux ship in the world, this is a unique system.The quality control of the flux datasets is essential as the data is collected continuously including during unfavorable conditions. Preliminary quality control was applied and the results show the reasonable values as compared to the bulk parameters. Based on the detailed quality control, the bulk transfer coefficients can be parameterized in various conditions. IntroductionIn order to understand the air-sea interaction in the climate system, direct eddy flux measurement is necessary as well as bulk aerodynamic algorithm. However, it is rarely experienced due to many difficulties as described in the next section. The present authors have experienced on-board eddy flux measurement including ship motion correction. Based on their experiences, an automated eddy flux measurement system was developed and can be used without unexperienced scientists. This system includes ship motion correction for the eddy covariance method and real-time, in-situ fluxes are monitored on-board.This can be applied to many ships cruising global oceans and should be helpful to realize sea surface energy fluxes. On-board direct eddy covariance systemDirect eddy covariance system requires fast response turbulence sensors which include a sonic anemometerthermometer and an infrared H2O/CO2 analyzer. This kind of eddy covariance system has been applied over land surfaces such as over plant canopies and bare soils including CO2 eddy flux measurements.However, application of the eddy covariance system over the ocean includes a lot of difficulties and very few measurements are reported as compared to land surface measurements. One of (and the most of) the difficulties 37 On-board Automated Eddy Flux Measurement System over Open Ocean

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Section: Quality Controlsupporting

confidence: 79%

“…Since then Fujitani (1985), Tsukamoto et al (1990), Tsukamoto and Ishida (1995) has developed and improved the correction scheme. Around the world, research groups (e.g., Edson et al 1998;Pedreros et al 2003) have developed on-board eddy flux system.…”

Section: On-board Direct Eddy Covariance Systemmentioning

confidence: 99%

On-board Automated Eddy Flux Measurement System over Open Ocean

Takahashi

Kondo

Tsukamoto

et al. 2005

SOLA

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“…The study of Pedreros et al (2003) is particularly interesting. It reports simultaneous measurements with Solent sonic anemometers of C HN on a ship and on an ASIS (Air-Sea Interaction Spar) buoy.…”

Section: Discussion and Comparison With Other Datamentioning

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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“…Direct comparisons between shipboard momentum-flux measurements and those from low-profile buoys or floating platforms (FLIPs) have shown significant differences (Pedreros et al, 2003;Edson et al, 1998). Landwehr et al (2015) showed that these discrepancies could be explained by inappropriate application of the platform motion correction and rotation of the wind vector, which can lead to overestimations of the deflection of the apparent wind vector and provided an adapted correction.…”

Section: Introductionmentioning

confidence: 99%

Using eddy covariance to measure the dependence of air–sea CO<sub>2</sub> exchange rate on friction velocity

et al. 2018

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Abstract. Parameterisation of the air-sea gas transfer velocity of CO 2 and other trace gases under open-ocean conditions has been a focus of air-sea interaction research and is required for accurately determining ocean carbon uptake. Ships are the most widely used platform for air-sea flux measurements but the quality of the data can be compromised by airflow distortion and sensor cross-sensitivity effects. Recent improvements in the understanding of these effects have led to enhanced corrections to the shipboard eddy covariance (EC) measurements.Here, we present a revised analysis of eddy covariance measurements of air-sea CO 2 and momentum fluxes from the Southern Ocean Surface Ocean Aerosol Production (SOAP) study. We show that it is possible to significantly reduce the scatter in the EC data and achieve consistency between measurements taken on station and with the ship underway. The gas transfer velocities from the EC measurements correlate better with the EC friction velocity (u * ) than with mean wind speeds derived from shipboard measurements corrected with an airflow distortion model. For the observed range of wind speeds (u 10 N = 3-23 m s −1 ), the transfer velocities can be parameterised with a linear fit to u * . The SOAP data are compared to previous gas transfer parameterisations using u 10 N computed from the EC friction velocity with the drag coefficient from the Coupled Ocean-Atmosphere Response Experiment (COARE) model version 3.5. The SOAP results are consistent with previous gas transfer studies, but at high wind speeds they do not support the sharp increase in gas transfer associated with bubblemediated transfer predicted by physically based models.

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Momentum and heat fluxes via the eddy correlation method on the R/V L'Atalante and an ASIS buoy

Cited by 41 publications

References 34 publications

On-board Automated Eddy Flux Measurement System over Open Ocean

On-board Automated Eddy Flux Measurement System over Open Ocean

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

Using eddy covariance to measure the dependence of air–sea CO<sub>2</sub> exchange rate on friction velocity

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Momentum and heat fluxes via the eddy correlation method on the R/V L'Atalante and an ASIS buoy

Cited by 41 publications

References 34 publications

On-board Automated Eddy Flux Measurement System over Open Ocean

On-board Automated Eddy Flux Measurement System over Open Ocean

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

Using eddy covariance to measure the dependence of air–sea CO&lt;sub&gt;2&lt;/sub&gt; exchange rate on friction velocity

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Using eddy covariance to measure the dependence of air–sea CO<sub>2</sub> exchange rate on friction velocity