Evaluation of atmosphere–land interactions in an LES from the perspective of heterogeneity propagation

Liu, Shaofeng; Hintz, M.; Li, Xiaolong

doi:10.1007/s00376-015-5212-6

Cited by 5 publications

(5 citation statements)

References 32 publications

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“…Recently, a new multiscale decomposition method, the orthogonal PDF decomposition (OPD) (Liu et al, 2015), has been proposed for pattern recognition and scale decomposition. It has been applied to surface heterogeneity quantification and turbulence structure identification (Liu et al, 2015(Liu et al, , 2016. The OPD performs decomposition in the PDF domain and its reconstruction for nonperiodic signals can be done more effectively than that of traditional wave-based transforms (e.g., Fourier transform, wavelet transform) which are performed in the physical space.…”

Section: Introductionmentioning

confidence: 99%

Further Improvement of Surface Flux Estimation in the Unstable Surface Layer Based on Large‐Eddy Simulation Data

et al. 2019

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The Monin-Obukhov similarity theory (MOST) is widely used for the surface turbulence flux-gradient relations in modeling and data analysis. Here we quantify multiscale turbulence processes by applying our newly developed analysis technique to large-eddy simulation data, and find that in the unstable surface layer, large convective eddies (with the scaling of boundary layer depth) and local free convection exist in addition to small eddies. An empirical MOST function (considering the last two processes only) is found to underestimate the surface friction velocity and heat flux both by about 30%. Much better results can be obtained using a function that explicitly considers all three processes. Generally, the nondimensional wind shear exhibits larger scatter and deviates more from the MOST than the temperature gradient. Based on these results, we propose the revised Sorbjan (1986, https://doi.org/10.1007/BF00120989) function (with coefficients determined from this study) for wind shear and MOST function for temperature gradient, for estimating surface fluxes in the unstable surface layer. The three-dimensional multiscale analysis method we develop in this study is of general nature and can be of interest for problems of three-dimensional multiscale process description in other disciplines.In this section, we will first present briefly the OPD technique and its extension to three dimensions (see Method S1 in the supporting information for details). The standard MOST and previous efforts to improve the flux-gradient relations for the unstable condition will be described as well. Finally, we will describe how the data used in this study are obtained via large-eddy simulation.

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Section: Introductionmentioning

confidence: 99%

Further Improvement of Surface Flux Estimation in the Unstable Surface Layer Based on Large‐Eddy Simulation Data

et al. 2019

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“…4 of 8 atmospheric boundary layer turbulence (e.g., Catalano & Moeng, 2010;G. Liu et al, 2011;Ma & Liu, 2017;Ma et al, 2020) and land-atmosphere interactions (e.g., Ma & Liu, 2019;Shao et al, 2013;S. Liu et al, 2016S.…”

Section: 1029/2022gl101754mentioning

confidence: 99%

“…In addition, we use the same LES model, that is, LES of the Weather Research and Forecasting model (WRF) (Skamarock et al., 2008), to generate more new data to evaluate the simplified formula. The WRF‐LES model has been widely used for studying atmospheric boundary layer turbulence (e.g., Catalano & Moeng, 2010; G. Liu et al., 2011; Ma & Liu, 2017; Ma et al., 2020) and land‐atmosphere interactions (e.g., Ma & Liu, 2019; Shao et al., 2013; S. Liu & Shao, 2013; S. Liu et al., 2016, 2017).…”

Section: Theory and Datamentioning

confidence: 99%

A Surface Flux Estimation Scheme Accounting for Large‐Eddy Effects for Land Surface Modeling

Liu

Zeng

Dai

et al. 2022

Geophysical Research Letters

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Land-atmosphere interaction is a crucial component of numerical weather and climate models. Predictions of these numerical models are sensitive to surface-air exchanges (i.e., surface fluxes) of energy, mass, and momentum. The surface fluxes are always subgrid-scale (SGS) processes that cannot be explicitly resolved but must be parameterized. The surface flux parameterization in almost all current numerical models is based on the Monin-Obukhov similarity theory (MOST; Monin & Obukhov, 1954).The MOST has been a fundamental theory for studying the atmospheric surface layer (ASL) since its proposal (Monin & Obukhov, 1954). According to the MOST, the statistical structure of the surface layer, under horizontally homogeneous and quasi-stationary conditions, is governed by four independent parameters: height above ground, surface friction velocity, kinematic surface heat flux, and a buoyancy parameter. The MOST has been widely tested with field measurements for mean wind and mean temperature gradients (e.g.

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“…The intense evapotranspiration makes the near surface temperature lower and the humidity higher over oases areas than in the surrounding deserts, making the oasis as a wet-cold island called oasis cold island (OCI) effect or oasis effect [4,5]. The OCI effect, which has already been confirmed by observational and numerical simulations studies [6][7][8], is thought to have an important impact on the sustainability of oasis [9][10][11][12]. In fact, the OCI effect may generate local atmospheric circulation called oasis-desert breeze circulation (OBC) [13], with a low-level divergent flow from the oasis to the surroundings desert and a convergent flow in the upper boundary layer.…”

Section: Introductionmentioning

confidence: 96%

Numerical Study of the Interaction between Oasis and Urban Areas within an Arid Mountains-Desert System in Xinjiang, China

Cai

Hamdi

et al. 2020

Atmosphere

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The rapid oasis expansion and urbanization that occurred in Xinjiang province (China) in the last decades have greatly modified the land surface energy balance and influenced the local circulation under the arid mountains-plain background system. In this study, we first evaluated the ALARO regional climate model coupled to the land surface scheme SURFEX at 4 km resolution using 53 national climatological stations and 5 automatic weather stations. We found that the model correctly simulates daily and hourly variation of 2 m temperature and relative humidity. A 4-day clear sky period has been chosen to study both local atmospheric circulations and their mutual interaction. Observations and simulations both show that a low-level divergence over oasis appears between 19:00 and 21:00 Beijing Time when the background mountain-plain wind system is weak. The model simulates a synergistic interaction between the oasis-desert breeze and urban-rural breeze from 16:00 until 22:00 with a maximum effect at 20:00 when the downdraft over oasis (updraft over urban) areas increases by 0.8 (0.4) Pa/s. The results show that the oasis expansion decreases the nocturnal urban heat island in the city of Urumqi by 0.8 °C, while the impact of urban expansion on the oasis cold island is negligible.

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Evaluation of atmosphere–land interactions in an LES from the perspective of heterogeneity propagation

Cited by 5 publications

References 32 publications

Further Improvement of Surface Flux Estimation in the Unstable Surface Layer Based on Large‐Eddy Simulation Data

Further Improvement of Surface Flux Estimation in the Unstable Surface Layer Based on Large‐Eddy Simulation Data

A Surface Flux Estimation Scheme Accounting for Large‐Eddy Effects for Land Surface Modeling

Numerical Study of the Interaction between Oasis and Urban Areas within an Arid Mountains-Desert System in Xinjiang, China

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