An Extension of the Mellor–Yamada Model to the Terra Incognita Zone for Dry Convective Mixed Layers in the Free Convection Regime

Ito, Junshi; Niino, Hiroshi; Nakanishi, Mikio; Moeng, Chin Hoh

doi:10.1007/s10546-015-0045-5

Cited by 71 publications

(64 citation statements)

References 30 publications

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“…Boutle et al (2014) applied aircraft observations to evaluate simulations of stratocumulus formation under the proposed scale-aware modifications to the Met Office Unified Model, while nesting domains from 4 km to 100 m and considering a period of 2 days. They found that the performance of the scale-aware ABLP at the GZ matched the performance of the well-established one-dimensional large-scale ABLP used for coarser grids, 20 and that of the three-dimensional small-scale parameterization typically used for micro scale grid sizes. Another study by Shin and Hong (2015) proposed a scale-aware ABLP in WRF and validated it for real cases considering 24 hours of observational data focusing on the development of a convective roll at ∆ xy = 333 m. They found that the newly proposed scheme enhanced the simulation of vertical motions under convective conditions but highlighted the need for further improvements which will cover a wider range of simulation scenarios.…”

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confidence: 80%

“…Another alternative is to fully couple the meso and micro scales within a single code. As a consequence of these new developments, 20 two important questions have emerged. Firstly, how best to prescribe initial and boundary conditions to the LES and whether to allow feedback between the scales when the coupling is performed within a single code.…”

Section: Durationmentioning

confidence: 99%

“…Under the first coupling approach, the GZ is avoided but turbulence generation methods must still be applied to the meso scale fields before they can be used as driving inflow to LES (Haupt et al, 2015;Mirocha et al, 2013). Under the second coupling approach, an adequate treatment of GZ resolutions is required and may be achieved by developing more flexible parameterizations (Shin and Dudhia, 2016;Ito et al, 2015) or by avoiding the GZ domains altogether and relying on turbulence generation strategies alone to couple meso and micro scale domains (Muñoz-Esparza et al, 2017).…”

Section: Durationmentioning

confidence: 99%

“…For example, Shin and Hong (2015) and Ito et al (2015) used idealized WRF-LES as benchmarks and developed scale-aware capabilities within existing ABL parameterizations (ABLPs) to regulate their role at GZ resolutions. So far, these and other ABLPs expanded to accommodate GZ resolutions are limited to convective boundary layers (CBLs) and have mostly been 10 verified against reference idealized LES (e.g., Shin and Dudhia (2016); Ito et al (2015); Kitamura (2015); Honnert et al (2011)).…”

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confidence: 99%

“…So far, these and other ABLPs expanded to accommodate GZ resolutions are limited to convective boundary layers (CBLs) and have mostly been 10 verified against reference idealized LES (e.g., Shin and Dudhia (2016); Ito et al (2015); Kitamura (2015); Honnert et al (2011)). The only existing work evaluating meso-micro coupled simulations with WRF for a real case avoided the GZ by using a high nesting ratio and going directly from the meso (1 km) to the micro scale (90 m) domain (Muñoz-Esparza et al, 2017).…”

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confidence: 99%

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Analysis of Different Gray Zone Treatments in WRF-LES Real Case Simulations

Doubrawa

Montornès²,

Barthelmie

et al. 2018

Preprint

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Abstract. When conducting meso-micro scale coupled atmospheric simulations, it is crucial to ensure an adequate treatment of gray zone or terra incognita resolutions in which a large portion of the kinetic energy is naturally produced by the momentum balance equations in the model, while the remaining part still needs to be parameterized. In this work, we conduct three multiday, real case, full-physics atmospheric simulations that are fully coupled from the meso to the micro scale and in which the only difference is the treatment of boundary layer physics at the gray zone domain. One simulation uses a well-established 5 parameterization, another uses its scale-aware version previously modified to accommodate gray zone resolutions, and a final one uses no parameterization at all and assumes that the gray zone domain can be run in large-eddy simulation (LES) mode.The simulated fields are cross-compared, and further compared to measurements collected during the Prince Edward Island Wind Energy Experiment. Use of LES in the gray zone domain influences the flow fields in a manner that is robust to temporal averaging. The best predictions of vertical wind shear were found for the simulations in which the gray zone is parameterized, 10 and the inclusion of a micro scale nest run in LES mode within the gray zone domains increased the model errors by producing overly homogeneous flow fields. The parameterized simulations also produced better agreement in terms of kinetic energy spectra at the two innermost simulation domains. In the gray zone domain, the energy decays as f −3 throughout most of the spectral range considered. In the micro scale domain, the same is only seen in the low-frequency end of the gray zone spectral range. In the high-frequency end, the energy decay follows a f −1 slope. Outside the gray zone spectral range, the micro scale 15 simulated spectra follow the expected f −5/3 slope and produce good agreement with measurements.

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confidence: 80%

Section: Durationmentioning

confidence: 99%

Section: Durationmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Analysis of Different Gray Zone Treatments in WRF-LES Real Case Simulations

Doubrawa

Montornès²,

Barthelmie

et al. 2018

Preprint

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Impact of urbanization patterns on the local climate of a tropical city, Singapore: An ensemble study

Koh

Panda

et al. 2016

JGR Atmospheres

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The effect of urbanization and urbanization pattern on the thermal environment and local rainfall is investigated in the tropical coastal city, Singapore. The Weather Research and Forecasting (WRF) model is employed with 5 one-way nested domains and the highest horizontal resolution is 300 m. The urban effect is taken into account by a single-layer urban canopy model. Several scenarios with idealized urbanization patterns are designed and simulated for an ensemble of 28 members. In the asymmetric urbanization scenarios, in which either the southern or northern part of Singapore is urbanized while the other part is forest, the magnitude of urban heat island (UHI) intensity is higher than that in the symmetric urbanization scenario, in which the urban and forest land use is homogeneously distributed in Singapore. The anthropogenic heat (AH) associated with the urban areas will exacerbate the UHI intensity. Most of the rainfall in the examined cases occurs from late morning to afternoon when the sea breeze blows northeastward. The results suggest that sea breezes have stronger influence on the rainfall than the urbanization pattern since the downwind part always gets more rainfall than the upwind part. The urbanization and associated AH can have two opposite effects on the rainfall amount: increasing rainfall through increasing buoyancy by AH and decreasing rainfall through reducing evaporation by converting greenery to impervious surfaces. The ultimate effect is dependent on the relative strength of these two influences.

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Grey zone simulations of the morning convective boundary layer development

et al. 2016

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Numerical simulations of two cases of morning boundary layer development are conducted to investigate the impact of grid resolution on mean profiles and turbulent kinetic energy (TKE) partitioning from the large eddy simulation (LES) to the mesoscale limit. Idealized LES, using the 3‐D Smagorinsky scheme, is shown to be capable of reproducing the boundary layer evolution when compared against measurements. However, increasing grid spacing results in the damping of resolved TKE and the production of superadiabatic temperature profiles in the boundary layer. Turbulence initiation is significantly delayed, exhibiting an abrupt onset at intermediate resolutions. Two approaches, the bounding of vertical diffusion coefficient and the blending of the 3‐D Smagorinsky with a nonlocal 1D scheme, are used to model subgrid diffusion at grey zone resolutions. Simulations are compared against the coarse‐grained fields from the validated LES results for each case. Both methods exhibit particular strengths and weaknesses, indicating the compromise that needs to be made currently in high‐resolution numerical weather prediction. The blending scheme is able to reproduce the adiabatic profiles although turbulence is underestimated in favor of the parametrized heat flux, and the spin‐up of TKE remains delayed. In contrast, the bounding approach gives an evolution of TKE that follows the coarse‐grained LES very well, relying on the resolved motions for the nonlocal heat flux. However, bounding gives unrealistic static instability in the early morning temperature profiles (similar to the 3‐D Smagorinsky scheme) because model dynamics are unable to resolve TKE when the boundary layer is too shallow compared to the grid spacing.

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An Extension of the Mellor–Yamada Model to the Terra Incognita Zone for Dry Convective Mixed Layers in the Free Convection Regime

Cited by 71 publications

References 30 publications

Analysis of Different Gray Zone Treatments in WRF-LES Real Case Simulations

Analysis of Different Gray Zone Treatments in WRF-LES Real Case Simulations

Impact of urbanization patterns on the local climate of a tropical city, Singapore: An ensemble study

Grey zone simulations of the morning convective boundary layer development

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