On Wind-Driven Current and Temperature Profiles with Diurnal Period in the Oceanic Planetary Boundary Layer

Kondo, Junsei; Sasano, Yasuhiro; Ishii, Tetsuo

doi:10.1175/1520-0485(1979)009<0360:owdcat>2.0.co;2

Cited by 50 publications

(23 citation statements)

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“…Water temperature was sensitive to wind speed. The daily range of water temperature under clear day conditions depended on wind speed; under strong wind conditions, the daily range of temperatures was small due to mechanical mixing processes caused by wind (Kondo et al 1979).…”

Section: Vertical Profile Observationsmentioning

confidence: 99%

“…Here, z is the solar zenith angle (i.e., the incident angle), and n (¼ 1:33) is the refractive index of water (Kondo et al 1979). The observation sites were the 500 m point ðÂÞ and the 3.5 km point ðaÞ.…”

Section: Vertical Profile Observationsmentioning

confidence: 99%

“…Solar radiation sharply decreased to 10% and 2% of the surface value at effective depths of around 1 m and 2 m, respectively. A thick solid line (cal(b ¼ 9)) shows the results of Kondo et al (1979), which corresponds to polluted water in a coastal area. Since a large quantity of blue-green algae grew in Erhai Lake, transmissivity of the lake water was low.…”

Section: Vertical Profile Observationsmentioning

confidence: 99%

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Features of Air-Lake Interaction in Heat and Water Exchanges over Erhai Lake

Haginoya

Fujii

Sun

et al. 2012

Journal of the Meteorological Society of Japan

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This paper presents the characteristics of air-lake-land interactions, which arise from the di¤erent thermal properties of lake and land surfaces, as observed at Erhai Lake in Yunnan Province, China. The heat balance over the lake was estimated by using data on the lake surface obtained from the Erhai automatic weather station and solving the surface heat balance equation (HBE) for a mixed layer. Meteorological station data were also used to estimate the long-term heat balance. The surface temperature from in situ observations was compared with that from satellite observations, and the two results were found to be in reasonably good agreement. The satellite data were used to validate the heat balance calculation. The mixed layer depth of Erhai Lake was 6 m in 2008 and 8 m from 2003 to 2008. Lake heat storage showed large annual variation of 50 W m À2 in amplitude, with a maximum from March to April and a minimum in November. The phases of the latent heat, the sensible heat, and the di¤erence between surface and air temperatures tended to be delayed on the lake as compared with the land. The phase lag in the seasonal variation of evaporation was found to clearly depend on lake depth. The daily change in convection over the lake-land system was greatest in the daytime over the mountainous area and in the nighttime over the lake area. These features arose from di¤erences in the thermal properties of the lake and land surfaces. Non-dimensional evaporation increased with increasing annual mean air temperature, and there was no systematic di¤erence between regions. Nearly 92% of solar radiation was absorbed by the lake within a depth of 2 m. From this finding, the daily range of the lake's surface temperature was quantitatively determined to be about 5 C.

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Section: Vertical Profile Observationsmentioning

confidence: 99%

Section: Vertical Profile Observationsmentioning

confidence: 99%

Section: Vertical Profile Observationsmentioning

confidence: 99%

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Features of Air-Lake Interaction in Heat and Water Exchanges over Erhai Lake

Haginoya

Fujii

Sun

et al. 2012

Journal of the Meteorological Society of Japan

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“…Thus, any model that includes some form of an EUC and also gives a reasonably good simulation of the depth of mixing (which requires only a shear flow stability condition) would give a similar result for the overall dissipation, e.g., the models of Mellor and Durbin (1975) or Kondo et al (1979) should do as well as this one if run under similar conditions.…”

Section: 32ii Nighttime Dissipationmentioning

confidence: 99%

Upper ocean dynamics during the LOTUS and TROPIC HEAT experiments

Schudlich¹

1991

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This thesis examines the effect of mean large-scale currents on the vertical structure of the upper ocean during two recent observational programs: the Long Term Upper Ocean Study (LOTUS) and the TROPIC HEAT experiments. The LOTUS experiment took place in the northwest Atlantic Ocean, a mid-latitude region away from strong mean currents, and extended over one entire seasonal cycle. The TROPIC HEAT experiments took place in the central equatorial Pacific Ocean during two 12-day periods in 1984 and 1987, at opposite extremes of the seasonal cycle. We use observations from these field experiments as well as one-dimensional numerical models of the upper ocean to analyze the dynamics of the vertical structure of the upper ocean at the equator and in mid-latitudes. Due to the different nature of the observations, we focus on the long term mean structure of the upper ocean in the LOTUS observations (Chapters 2 and 3), and on the diurnal cycle in the equatorial upper ocean in our analysis of the TROPIC HEAT observations (Chapters 4 and 5).In the LOTUS observations, we find that the observed current is coherent with the wind over low frequencies (greater than an inertial period). Using a wind-relative averaging method we find good agreement with Ekman transport throughout the first summer and winter of the LOTUS experiment, with the exception of a downwind component in the wintertime. The mean current spiral is flat compared to the classic Ekman spiral, in that it rotates less with depth than does the Ekman spiral. The mean current has an e-folding depth scale of 12 m in the summer and 25 m in the winter.Diurnal cycling is the dominant variability in the summer and determines the vertical structure of the spiral. In the winter, diurnal cycling is almost non-existent due to greatly reduced solar insolation. There is a persistent downwind shear in the upper 15 m during the winter which may be partially due to a bias induced by surface wave motion but which is also consistent with a logarithmic boundary layer.The Price et al. (1986) model is reasonably successful in simulating the current structure during the summer, capturing both the mean and the diurnal variation. The model is less successful in the winter, though it does capture the overall depth scale of the current spiral.In our analysis of the TROPIC HEAT observations, we extend the Price et al. (1986) model to the equatorial upper ocean. The model is initialized with the stratification and shear of the Equatorial Undercurrent (EUC), and is driven with heating and wind stress. A surface mixed layer is determined by bulk stability requirements, and a transition layer below the mixed layer is simulated by requiring that the gradient Richardson number be no less than 1/4. A principal result is that the nighttime phase of the diurnal cycle is strongly affected by the EUC, resulting in deep mixing and large dissipation at night consistent with observations of the equatorial upper ocean during TROPIC HEAT. Other features of the equatorial circulation (upwelling and...

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“…Thus the velocity is surface intensifi ed during daytime under fair weather condi tions [Price et al, 1986]. For cases like this, Kondo et al [1979] computed eddy viscosities of the order of 10 at the surface which increased during nighttime to the order of 1000 in 10-m depth and remained about 50 cgs units below. As a consequence, the clockwise deviation of the current from the wind direction was larger during the day than during the night.…”

Section: Introductionmentioning

confidence: 97%

Ekman drift in homogeneous water

Krauß¹

1993

J. Geophys. Res.

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Measurements made with satellite-tracked buoys drogued in different layers between the sea surface and 30-m depth under homogeneous winter conditions in the North Sea allow analysis of the Ekman currents under a large variety of wind conditions. The experiment lasted from November 20, 1991, until February 29, 1992. The first 4 weeks of this period, during which the buoys stayed close together, are used to determine the Ekman stresses. The total current field is a superposition of barotropic currents due to sea level variations and Ekman currents. The classical Ekman theory is not able to describe properly the observed deflection of the currents to the right of the wind direction and their decay with depth. This deflection is 10° near the sea su1face and increases to approximately 50° in 25-m depth. The relation between wind stress and the stress field in the interior of the water is given by a tensor, which describes the rotation and the variation of the stress with increasing depth. The concept of eddy viscosity is applicable, if a viscosity tensor is used to relate stress and vertical shear. The viscosity tensor is a function of the vertical coordinate only and is independent from the wind stress. It shows maximum values in 15-to 20-m depth and may be due to Langmuir circulation cells. Further studies are needed to determine the physics of this tensor. Its magnitude in the interior of the mixed layer exceeds 1000 cgs units. Consequently, Ekman currents are weak and may not be the dominant currents within the mixed layer.

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On Wind-Driven Current and Temperature Profiles with Diurnal Period in the Oceanic Planetary Boundary Layer

Cited by 50 publications

References 0 publications

Features of Air-Lake Interaction in Heat and Water Exchanges over Erhai Lake

Features of Air-Lake Interaction in Heat and Water Exchanges over Erhai Lake

Upper ocean dynamics during the LOTUS and TROPIC HEAT experiments

Ekman drift in homogeneous water

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