Aircraft measurements of boundary-layer turbulence over the central Equatorial Pacific Ocean

Greenhut, Gary K.; Bean, B. R.

doi:10.1007/bf00119904

Cited by 12 publications

(8 citation statements)

References 14 publications

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“…Since the boundary layer mean wind speed measured along the transect was the same on both sides of the front (Table 2) cients are (1.8 _+ 0.1) x 10 -3 for latent heat on both sides of the front and (0.9 -+ 0.2) x 10 -3 for sensible heat on the warm side. These are in reasonable agreement with values obtained previously in the MABL [e.g., Greenhut and Bean, 1981] and therefore support the procedures used to obtain the sea-air differences in Table 1. Larger sea-air temperature and moisture differences on the warm side of the front should produce greater atmospheric instability and therefore larger surface momentum flux on the warm side than on the cold side. The opposite is observed in the data taken during the transect (Table 2).…”

Section: Secondary Circulations In the Vicinity Of An Sst Front Have supporting

confidence: 91%

Atmospheric turbulence structure in the vicinity of an oceanic front

Khalsa¹,

Greenhut²

1989

J. Geophys. Res.

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Fast response data taken aboard the National Oceanic and Atmospheric Administration WP‐3D aircraft are used to determine the structure of atmospheric boundary layer turbulence on either side of a well‐developed sea surface temperature front southwest of Bermuda. The data were taken on February 17, 1986, as part of the Frontal Air‐Sea Interaction Experiment (FASINEX). A broad region of low‐humidity air extending from 15 km to 35 km south of the front is probably due to the presence of a frontally induced secondary circulation. Evidence for a secondary flow is found in both the time series of atmospheric variables and the statistics obtained from conditionally sampled updrafts and downdrafts in the transect across the SST front. Larger sea‐air temperature and humidity differences on the warm (south) side of the front give rise to surface layer sensible and latent heat and buoyancy fluxes that are larger than those on the cold side. Turbulence structure appears to be influenced as much by the presence of strong wind shear at the top of the boundary layer as by differing conditions at the surface on either side of the front. A larger rate of entrainment on the warm side of the front is indicated by the greater influence of low‐momentum air from the overlying shear layer on updrafts in the upper part of the mixed layer, as well as the more frequent overturning of cool/moist updrafts and warm/dry downdrafts. It is conjectured that the larger entrainment rate is due to the interaction between the inversion layer and more energetic updrafts produced by greater surface forcing on the warm side of the front.

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Section: Secondary Circulations In the Vicinity Of An Sst Front Have supporting

confidence: 91%

Atmospheric turbulence structure in the vicinity of an oceanic front

Khalsa¹,

Greenhut²

1989

J. Geophys. Res.

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“…The solid lines are least-square linear fits to the data. For comparison, the dashed lines are profiles obtained over the central equatorial Pacific during an earlier series of EPOCS flights (Greenhut and Bean, 1981). The cooler and drier conditions observed over the eastern Pacific, and the correspondingly lower values of saturation water vapor density, are presumably the result of coastal upwelling.…”

Section: Flux Profilesmentioning

confidence: 99%

“…The surface layer fluxes of latent heat, buoyancy and momentum are 73 W/m2, 7.2 W/m2 and 0.057 N/m', respectively. From these values, the representative Monin--Obukhov length is -120 m and the surface roughness length is 6.5 x 10m5 m. Reduction of the calculated drag coefficient to a height of 10 m is made using surface layer similarity (Greenhut and Bean, 1981) with the result C,(lO) = 1.3 x 1o-3 appropriate to a mean surface layer wind speed of 6.5 m s-'. The drag coefftcient over the central Pacific was found to be 1.6 x 1O-3 for a mean wind speed of 8.5 m SK'.…”

Section: Flux Profilesmentioning

confidence: 99%

Stability dependence of fluxes and bulk transfer coefficients in a tropical boundary layer

Greenhut¹

1982

Boundary-Layer Meteorol

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Turbulence data obtained abo+rd a NOAA P-3 research aircraft during flights over the eastern equatorial Pacific Ocean are used to obtain mean vertical profiles of water vapor density, potential temperature, wind speed and fluxes of latent heat, buoyancy and momentum. The variation of eddy fluxes and bulk transfer coefficients as a function of atmospheric stability are plotted for two of the flights. The observed transfer coefficients generally agree with those obtained from parameterizations based on surfacelayer similarity theory (Deardorff, 1968;Kondo, 1975).

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“…So it is not adequate to include this correction to the latent heat flux. When Brook's correction is applied to bulk formula, Greenhut and Bean (1981) used the following scheme after Reinking (1980),…”

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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Aircraft measurements of boundary-layer turbulence over the central Equatorial Pacific Ocean

Cited by 12 publications

References 14 publications

Atmospheric turbulence structure in the vicinity of an oceanic front

Atmospheric turbulence structure in the vicinity of an oceanic front

Stability dependence of fluxes and bulk transfer coefficients in a tropical boundary layer

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

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