Generalized Non-dimensional Wind and Temperature Gradients in the Surface Layer

Sakagami, Yoshiaki; Haas, Reinaldo; Passos, Júlio César

doi:10.1007/s10546-020-00510-3

Cited by 2 publications

(9 citation statements)

References 40 publications

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“…where the first two linear terms on the right side of the equation may be associated with the mechanical ρu ′ m w ′ m and thermal ρu ′ h w ′ h contributions of Reynolds stress as demonstrated by Sakagami et al (2020). This study shows that these mechanical and thermal Reynolds stress components are derived from generalized non-dimensional wind and temperature gradients, which are in agreement with the literature of the Monin-Obukhov similarity theory (Högström 1988;Foken 2006).…”

Section: Reynolds Stresssupporting

confidence: 87%

“…where K is the eddy viscosity coefficient and the neutral shear ∂ Ūn /∂z and thermal shear ∂ Ūh /∂z are described in Section 2.2. For these two unknown nonlinear stress terms, we consider that the four terms from generalized wind and temperature profiles proposed by Sakagami et al (2020) should be associated with the four terms of the total Reynolds stress in Eq. 7.…”

Section: Reynolds Stressmentioning

confidence: 99%

“…Here, the well-known z/L parameter (Foken and Börngen 2021) was replaced by the non-dimensional stability parameter (zθ * /z h θ). In addition, two nonlinear terms (φ a and φ c ) were added from previous generalized non-dimensional function (Sakagami et al 2020).…”

Section: Non-dimensional Gradientmentioning

confidence: 99%

“…In this context, we propose non-dimensional wind and temperature gradients under stable, neutral and unstable conditions for the ABL in a single function. The proposed function is developed from a previous study (Sakagami et al 2020), and two reformulations are implemented. First, the thermal part of the wind shear is modified based on a surface temperature scale instead of the Obukhov length.…”

Section: Introductionmentioning

confidence: 99%

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Non-dimensional Wind and Temperature Gradients in the Atmospheric Boundary Layer

Sakagami

Acevedo

Maroneze

et al. 2022

Preprint

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We propose a single non-dimensional expression for the wind and temperature vertical profiles in the atmospheric boundary layer (ABL). Two major reformulations are implemented from the generalized function for dimensionless wind and temperature gradients, so that the theory from previous studies may be extended above the surface layer. First, the thermal part of the wind shear is modified based on a surface temperature scale θ* and a thermal-characteristic height zh instead of the Obukhov length. Second, we introduce two new terms in the total Reynolds stress associated with the nonlinear parts of the thermal-mechanical stress, where coefficients α and β maybe describe wind profiles of the low-level jets. The proposed wind and temperature profiles are compared with the universal function in the surface layer and validated with Wangara's wind and temperature profiles up to a height of 2 km, and their measurements of surface turbulent fluxes of heat and momentum. One case of unstable and four cases of stable conditions are selected from the Wangara dataset, representing cases of convective, stratified, nocturnal jet and transition between the stratified and jet profiles. The proposed function has a good correlation in the five cases of temperature and wind profiles with RMSE better than 0.7 K and 0.7 m s-1 respectively. The coefficients zh and b associated with the linear part of Reynolds stress, and the coefficients α and β associated with the nonlinear part of Reynolds stress are analized, and their possible physical meanings are discussed.

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Section: Reynolds Stresssupporting

confidence: 87%

Section: Reynolds Stressmentioning

confidence: 99%

Section: Non-dimensional Gradientmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Non-dimensional Wind and Temperature Gradients in the Atmospheric Boundary Layer

Sakagami

Acevedo

Maroneze

et al. 2022

Preprint

Self Cite

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“…Reviews of the first experiments and MOST can be found in Hicks and Baldocchi (2020) and references therein. Due to the diversity of measurements analyzed up to the present, new functions and coefficients are still proposed (Sakagami et al 2020).…”

Section: Introductionmentioning

confidence: 99%

Flux–Gradient Relationships Below 2 m Over a Flat Site in Complex Terrain

Martí

Martínez‐Villagrasa

Cuxart

2022

Boundary-Layer Meteorol

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The surface–atmosphere turbulent exchange fluxes are experimentally determined using the eddy-covariance method. Their estimation using profiles of the variables of interest is a less costly alternative, although restricted to certain ranges of stability and assumed to hold for relatively flat and homogeneous terrain. It relays usually on the prescription of the roughness lengths for momentum, heat and matter, the latter two being adjustable parameters with unclear physical significance. The relations are derived with data from screen level to a few tens of metres upward. The application of these expressions using data only at one level in the surface layer implies assuming zero wind speed and the land surface temperature at their respective roughness lengths. The latter is a quantity that experimentally can only be determined radiatively with a substantial uncertainty. In this work the flux-profile relationships for momentum and sensible heat are assessed over a flat site in moderately inhomogeneous complex terrain in the southern pre-Pyrenees, using data between 2 m and the surface. The main findings are that (i) the classical expressions hold in the daytime for most of the dataset, (ii) the iterative estimations using the Obukhov length and the direct ones using the bulk Richardson number provide very similar results, (iii) using a second observation of temperature avoids a radiometric measure of land surface temperature and the prescription of a thermal roughness length value, (iv) the estimations over wet terrain with high irradiance depart largely from observations.

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Generalized Non-dimensional Wind and Temperature Gradients in the Surface Layer

Cited by 2 publications

References 40 publications

Non-dimensional Wind and Temperature Gradients in the Atmospheric Boundary Layer

Non-dimensional Wind and Temperature Gradients in the Atmospheric Boundary Layer

Flux–Gradient Relationships Below 2 m Over a Flat Site in Complex Terrain

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