Turbulent diffusivity and diurnal variations in the atmospheric boundary layer

Yasuda, Nobuhisa

doi:10.1007/bf00128403

Cited by 18 publications

(8 citation statements)

References 12 publications

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“…This is different from the case in the atmospheric boundary layer (within the altitudes of a few hundred metres) where turbulence has a prominent diurnal variation reaching a maximum around midday (e.g. Yasuda, 1988;Englberger and Dörnbrack, 2016).…”

Section: Climatology Of Turbulence With Radarcontrasting

confidence: 59%

Derivation of turbulent energy dissipation rate with the Middle Atmosphere Alomar Radar System (MAARSY) and radiosondes at Andøya, Norway

Rapp

Schrön

et al. 2016

Ann. Geophys.

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Abstract. We present the derivation of turbulent energy dissipation rate ε from a total of 522 days of observations with the Middle Atmosphere Alomar Radar SYstem (MAARSY) mesosphere-stratosphere-troposphere (MST) radar running tropospheric experiments during the period of 2010-2013 as well as with balloon-borne radiosondes based on a campaign in the summer 2013. Spectral widths are converted to ε after the removal of the broadening effects due to the finite beam width of the radar. With the simultaneous in situ measurements of ε with balloon-borne radiosondes at the MAARSY radar site, we compare the ε values derived from both techniques and reach an encouraging agreement between them. Using all the radar data available, we present a preliminary climatology of atmospheric turbulence in the UTLS (upper troposphere and lower stratosphere) region above the MAARSY site showing a variability of more than 5 orders of magnitude inherent in turbulent energy dissipation rates. The derived ε values reveal a log-normal distribution with a negative skewness, and the ε profiles show an increase with height which is also the case for each individual month. Atmospheric turbulence based on our radar measurements reveals a seasonal variation but no clear diurnal variation in the UTLS region. Comparison of ε with the gradient Richardson number Ri shows that only 1.7 % of all the data with turbulence occur under the condition of Ri < 1 and that the values of ε under the condition of Ri < 1 are significantly larger than those under Ri > 1. Further, there is a roughly negative correlation between ε and Ri that is independent of the scale dependence of Ri. Turbulence under active dynamical conditions (velocity of horizontal wind U > 10 m s −1 ) is significantly stronger than under quiet conditions (U < 10 m s −1 ). Last but not least, the derived ε values are compared with the corresponding vertical shears of background wind velocity showing a linear relation with a corresponding correlation coefficient r = 58 % well above the 99.9 % significance level. This implies that wind shears play an important role in the turbulence generation in the troposphere and lower stratosphere (through the Kelvin-Helmholtz instability).

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Section: Climatology Of Turbulence With Radarcontrasting

confidence: 59%

Derivation of turbulent energy dissipation rate with the Middle Atmosphere Alomar Radar System (MAARSY) and radiosondes at Andøya, Norway

Rapp

Schrön

et al. 2016

Ann. Geophys.

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“…Aerodynamic conductance in a well‐mixed layer was estimated by where k is Von Karmen's constant (0.40 dimensionless), u is horizontal wind speed (m s −1 ), Z x is measurement height (m), d is the zero‐plane displacement (m), Z m is the aerodynamic roughness length, and Ψ m and Ψ h are the diabatic correction factors (m) for momentum and sensible heat, respectively [ Yasuda , 1988; Arya , 1988]. Zero‐plane displacement and aerodynamic roughness changed with stability and were empirically estimated for this study site [ Loescher et al , 2003].…”

Section: Methodsmentioning

confidence: 99%

Characterization and dry deposition of carbonaceous aerosols in a wet tropical forest canopy

et al. 2004

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[1] Carbon aerosol concentration was measured using an impactor on a 42 m tower over a wet tropical forest in northeast Costa Rica. Samples were collected at three different heights, 42, 21, and 2 m, for 2 months during the wet season in 1998. Winds originated from two directions, southeast from the Caribbean Sea and west from the continental isthmus. Concentrations were normalized by the fraction of dry sampling time during the collection. The distribution was negatively skewed for the range of aerodynamic diameter aerosols measured. The main size constituent was in the class 4.7-3.3 mm, accounting for $0.70 mg C mol À1 . No significant difference was found in the distribution of aerosol carbon with height, suggesting a well-mixed column of air, minimal resuspension, and that the source was from surrounding land use types. Functional relationships were developed to describe the loading of aerosols to the atmosphere and the removal by precipitation. Deposition was estimated using these relationships, combined with three different estimates of velocity deposition derived from (1) aerodynamic and canopy conductance, (2) aerodynamic and momentum conductance, and (3) traditional estimates of gravitational settling diffusion, impaction, and interception. Annual deposition estimates were 2.9, 5.0, and 9.6 kg ha À1 yr À1 , respectively. Concentrations of carbon aerosols reported here are as much as two orders of magnitude higher than those reported elsewhere. Annual dry deposition estimates, however, were within the range of other estimates but were likely underestimated. Potential effects on deposition caused by seasonal burns and El Niño-Southern Oscillation are discussed.

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“…where k is von Karman's constant (0.40), d is the zeroplane displacement (m), z m is the aerodynamic roughness length (m), and J m and J h are the diabatic correction factors (dimensionless) for momentum and sensible heat, respectively (Yasuda, 1988;Arya, 1988). Zero-plane displacement and aerodynamic roughness changed with stability and were empirically estimated for this study period (Loescher et al, 2003).…”

Section: Modeled Conductance and Evapotranspirationmentioning

confidence: 99%

Energy dynamics and modeled evapotranspiration from a wet tropical forest in Costa Rica

Loescher

Gholz

Jacobs

et al. 2005

Journal of Hydrology

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Turbulent diffusivity and diurnal variations in the atmospheric boundary layer

Cited by 18 publications

References 12 publications

Derivation of turbulent energy dissipation rate with the Middle Atmosphere Alomar Radar System (MAARSY) and radiosondes at Andøya, Norway

Derivation of turbulent energy dissipation rate with the Middle Atmosphere Alomar Radar System (MAARSY) and radiosondes at Andøya, Norway

Characterization and dry deposition of carbonaceous aerosols in a wet tropical forest canopy

Energy dynamics and modeled evapotranspiration from a wet tropical forest in Costa Rica

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