Surface Heterogeneity Effects on Regional-Scale Fluxes in the Stable Boundary Layer: Aerodynamic Roughness Length Transitions

Miller, Nathan E.; Stoll, Rob

doi:10.1007/s10546-013-9839-5

Cited by 15 publications

(7 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Second, the parameterization of subgrid‐scale surface heterogeneity effects in numerical models has been studied for more than three decades now but continues to be one of the most challenging issues facing the land and atmospheric modeling communities (Bou‐Zeid et al, ; ; Brutsaert, ; Chen & Avissar, ; ; Dalu et al, ; Li & Avissar, ; Mahrt, ; ; ; Maronga & Raasch, ; Miller & Stoll, ; Patton et al, ; Pielke & Uliasz, ; Pielke et al, ; Stoll & Porté‐Agel, ; Zeng & Pielke, ; ; Zhou et al, ). Currently, many land surface models use the so‐called mosaic or tiling approach to parameterize the subgrid‐scale surface heterogeneity effects on land‐atmosphere exchanges (Avissar & Pielke, ; Giorgi & Avissar, ; Koster & Suarez, ; Li et al, ), which in essence is based on the conceptualization shown in Figure a.…”

Section: Discussionmentioning

confidence: 99%

Sensitivity of Surface Temperature to Land Use and Land Cover Change‐Induced Biophysical Changes: The Scale Issue

Wang

2019

Geophysical Research Letters

View full text Add to dashboard Cite

While the signs of the sensitivities of surface temperature (Ts) to land use and land cover change‐induced biophysical changes are relatively well understood, their exact magnitude and how their magnitude depends on the scale characterizing the size of the change remain elusive. In this study, we compare the sensitivities of surface temperature to changes in surface albedo and surface water availability from three analytical/semianalytical models, which are designed for small (<1 km), intermediate (from ∼1 to ∼10 km), and large (>10–20 km) scales. Results suggest that the sensitivities of surface temperature to biophysical changes are scale dependent due to atmospheric feedbacks. Our results demonstrate that it is important to consider the scale and the associated atmospheric feedbacks when quantifying the sensitivities of surface temperature to biophysical changes.

show abstract

Section: Discussionmentioning

confidence: 99%

Sensitivity of Surface Temperature to Land Use and Land Cover Change‐Induced Biophysical Changes: The Scale Issue

Wang

2019

Geophysical Research Letters

View full text Add to dashboard Cite

show abstract

“…First is the flow configuration, which is boundary layer in the experiments, while is typically full channel or open-channel flow in the computations. Second is Re τ , which is of the order 10 3 in the experiments (Antonia & Luxton 1971;Hanson & Ganapathisubramani 2016), while is of the order 10 5 − 10 6 in the WMLES studies (Miller & Stoll 2013;Silva-Lopes et al 2015) and is about 200−1000 in the DNS studies (Lee 2015;Ismail et al 2018).…”

Section: Introductionmentioning

confidence: 94%

Direct numerical simulation of open-channel flow over smooth-to-rough and rough-to-smooth step changes

2019

View full text Add to dashboard Cite

Direct numerical simulations (DNS) are reported for open-channel flow over streamwise-alternating patches of smooth and fully rough walls. The rough patch is a three-dimensional sinusoidal surface. Owing to the streamwise periodicity, the flow configuration consists of a step change from smooth to rough, and a step change from rough to smooth. The friction Reynolds number varies from 437 over the smooth patch to 704 over the rough patch. Through the fully resolved DNS dataset it is possible to explore many detailed aspects of this flow. Two aspects motivate this work. The first one is the equilibrium assumption that has been widely used in both experiments and computations. However, it is not clear where this assumption is valid. The detailed DNS data reveal a significant departure from equilibrium, in particular over the smooth patch. Over this patch, the mean velocity is recovered up to the beginning of the log layer after a fetch of five times the channel height. However, over the rough patch, the same recovery level is reached after a fetch of two times the channel height. This conclusion is arrived at by assuming that an error of up to 5 % is acceptable and the log layer, classically, starts from 30 wall units above the wall. The second aspect is the reported internal boundary-layer (IBL) growth rates in the literature, which are inconsistent with each other. This is conjectured to be partly caused by the diverse IBL definitions. Five common definitions are applied for the same DNS dataset. The resulting IBL thicknesses are different by 100 %, and their apparent power-law exponents are different by 50 %. The IBL concept, as a layer within which the flow feels the surface underneath, is taken as the basis to search for the proper definition. The definition based on the logarithmic slope of the velocity profile, as proposed by Elliot (Trans. Am. Geophys. Union, vol. 39, 1958, pp. 1048–1054), yields better consistency with this concept based on turbulence characteristics.

show abstract

“…The simulated turbulence close to the surface depends on the prescribed roughness length (Zilitinkevich et al 2006). Miller and Stoll (2013) analyzed how the results of the GABLS1 intercomparison depend on the momentum and thermal roughness lengths showing a decrease of surface friction velocity, boundary-layer height and Obukhov length with lower roughness lengths. Here, we have tested how the results for this more stable case depend on prescribed values of roughness length.…”

Section: Roughness Lengthmentioning

confidence: 99%

Intercomparison of Large-Eddy Simulations of the Antarctic Boundary Layer for Very Stable Stratification

Couvreux

Bazile

Rodier

et al. 2020

Boundary-Layer Meteorol

View full text Add to dashboard Cite

In polar regions, where the boundary layer is often stably stratified, atmospheric models produce large biases depending on the boundary-layer parametrizations and the parametrization of the exchange of energy at the surface. This model intercomparison focuses on the very stable stratification encountered over the Antarctic Plateau in 2009. Here, we analyze results from 10 large-eddy-simulation (LES) codes for different spatial resolutions over 24 consecutive hours, and compare them with observations acquired at the Concordia Research Station during summer. This is a challenging exercise for such simulations since they need to reproduce both the 300-m-deep convective boundary layer and the very thin stable boundary layer characterized by a strong vertical temperature gradient (10 K difference over the lowest 20 m) when the sun is low over the horizon. A large variability in surface fluxes among the different models is highlighted. The LES models correctly reproduce the convective boundary layer in terms of mean profiles and turbulent characteristics but display more spread during stable conditions, which is largely reduced by increasing the horizontal and vertical resolutions in additional simulations focusing only on the stable period. This highlights the fact that very fine resolution is needed to represent such conditions. Complementary sensitivity studies are conducted regarding the roughness length, the subgrid-scale turbulence closure as well as the resolution and domain size. While we find little dependence on the surface-flux parametrization, the results indicate a pronounced sensitivity to both the roughness length and the turbulence closure.

show abstract

Surface Heterogeneity Effects on Regional-Scale Fluxes in the Stable Boundary Layer: Aerodynamic Roughness Length Transitions

Cited by 15 publications

References 58 publications

Sensitivity of Surface Temperature to Land Use and Land Cover Change‐Induced Biophysical Changes: The Scale Issue

Sensitivity of Surface Temperature to Land Use and Land Cover Change‐Induced Biophysical Changes: The Scale Issue

Direct numerical simulation of open-channel flow over smooth-to-rough and rough-to-smooth step changes

Intercomparison of Large-Eddy Simulations of the Antarctic Boundary Layer for Very Stable Stratification

Contact Info

Product

Resources

About