A Method for Increasing the Turbulent Kinetic Energy in the Mellor–Yamada–Janjić Boundary-Layer Parametrization

Foreman, Richard; Emeis, Stefan

doi:10.1007/s10546-012-9727-4

Cited by 15 publications

(11 citation statements)

References 31 publications

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“…The larger TKE predicted by MYNN2 and that parameterized by equations ()–() for the three cases strengthen the conclusion that MYJ underpredicts TKE. Note that there are other ways to enhance the TKE predictions from MYJ; for example, Foreman and Emeis [] modified the closure constants and the surface length scale in MYJ and obtained larger TKE predictions that are closer to the observations. Those suggested modifications for the Mellor‐Yamada model will be evaluated against LES results and observations over different stability conditions in a future study.…”

Section: Wrf Simulations Across Se England In June and Novembermentioning

confidence: 99%

Structure of the planetary boundary layer over Southeast England: Modeling and measurements

et al. 2013

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[1] The Weather Research and Forecasting model was applied to analyze variations in the planetary boundary layer (PBL) structure over Southeast England including central and suburban London. The parameterizations and predictive skills of two nonlocal mixing PBL schemes, YSU and ACM2, and two local mixing PBL schemes, MYJ and MYNN2, were evaluated over a variety of stability conditions, with model predictions at a 3 km grid spacing. The PBL height predictions, which are critical for scaling turbulence and diffusion in meteorological and air quality models, show significant intra-scheme variance (> 20%), and the reasons are presented. ACM2 diagnoses the PBL height thermodynamically using the bulk Richardson number method, which leads to a good agreement with the lidar data for both unstable and stable conditions. The modeled vertical profiles in the PBL, such as wind speed, turbulent kinetic energy (TKE), and heat flux, exhibit large spreads across the PBL schemes. The TKE predicted by MYJ were found to be too small and show much less diurnal variation as compared with observations over London. MYNN2 produces better TKE predictions at low levels than MYJ, but its turbulent length scale increases with height in the upper part of the strongly convective PBL, where it should decrease. The local PBL schemes considerably underestimate the entrainment heat fluxes for convective cases. The nonlocal PBL schemes exhibit stronger mixing in the mean wind fields under convective conditions than the local PBL schemes and agree better with large-eddy simulation (LES) studies.

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Section: Wrf Simulations Across Se England In June and Novembermentioning

confidence: 99%

Structure of the planetary boundary layer over Southeast England: Modeling and measurements

et al. 2013

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“…Mellor and Yamada 1982;Nakanishi 2001;Foreman and Emeis 2012). As the original set of constants results in a turbulence cut-off at Ri c = 0.21, we have opted here for another set, based on a fit to atmospheric data (Łobocki 1993) that shifts Ri c to 0.56.…”

Section: Model Constantsmentioning

confidence: 99%

“…Janjić 1990;Gerrity et al 1994), the Japanese JMA-NHM model (Saito et al 2007), mesoscale atmospheric research (e.g. the WRF model (Sušelj and Sood 2010;Foreman and Emeis 2012)), ocean modelling (e.g. Blumberg and Mellor 1987;Kantha and Clayson 1994;Burchard and Bolding 2001), and global atmospheric models (e.g.…”

mentioning

confidence: 99%

Analysis of Vertical Turbulent Heat Flux Limit in Stable Conditions with a Local Equilibrium, Turbulence Closure Model

Łobocki

2013

Boundary-Layer Meteorol

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Assuming that the vertical turbulent heat flux vanishes at extremely stable conditions, one should expect its maximal absolute value to occur somewhere at moderate stability, between a neutral and extremely stable equilibrium. Consequently, in some situations duality of solutions may be encountered (e.g. two different values of temperature difference associated with the same values of heat flux and wind speed). A quantitative analysis of this feature with a local equilibrium Reynolds-stress model is presented. The fixed-wind / fixed-shear maximum has been identified both in the bulk and in single-point flux-gradient relationships (that is, in the vertical temperature gradient and wind-shear parameter domain). The value of the Richardson number corresponding to this maximum is derived from the model equations. To study the possible feedback in strongly stable conditions, weak and intense cooling scenarios have been simulated with a one-dimensional numerical, high-resolution atmospheric boundary-layer model. Despite the rapid cooling, flow decoupling at the surface has not been observed; instead, a stability-limited heat flux is maintained, with a gradual increase of the Richardson number towards the top of the turbulent layer, with some signs of oscillatory behaviour at intermediate heights. Vertical changes of wind shear and the Brunt-Väisälä frequency display a remarkably non-monotonic character, with some signs of a gradually developing instability.

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“…One study showed promising results with a method for enhancing the TKE in the MYJ scheme, giving more correct results for the TKE in hub height in stable conditions. Nielsen‐Gammon et al . reported that ‘data assimilation methods are capable of extracting significant information about parameterization behavior from the observations, and thus can be used to estimate model parameters while they adjust the model state’.…”

Section: Discussionmentioning

confidence: 99%

“…One study showed promising results with a method for enhancing the TKE in the MYJ scheme, giving more correct results for the TKE in hub height in stable conditions. 25 Nielsen-Gammon et al reported that 'data assimilation methods are capable of extracting significant information about parameterization behavior from the observations, and thus can be used to estimate model parameters while they adjust the model state'. 26 In that paper, 10 parameters in the ACM2 scheme were tested, and it was found that the three most sensitive parameters in the ACM2 scheme were an exponent in the formulation of the boundary layer scaling vertical eddy diffusivity, the value of the minimum eddy diffusivity and the critical Richardson number that defines the PBL height.…”

Section: Discussionmentioning

confidence: 99%

Validation of boundary layer parameterization schemes in the Weather Research and Forecasting (WRF) model under the aspect of offshore wind energy applications—part II: boundary layer height and atmospheric stability

Krogsæter

Reuder

2014

Wind Energy

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Five different planetary boundary layer (PBL) schemes in the Weather Research and Forecasting (WRF) model have been tested with respect to their capability to model boundary layer parameters relevant for offshore wind deployments. For the year 2005, model simulations based on the YSU, ACM2, QNSE, MYJ and MYNN2 PBL schemes with WRF have been performed for the North Sea and validated against measurements from the FINO1 platform. In part I, the investigations had focused on the key parameters 100 m mean wind speed and wind shear in terms of the power‐law exponent. In part II, the focus is now set on the capability of the model to represent height and stability of the marine atmospheric boundary layer.Considerable differences are found among the PBL schemes in predicting the PBL height. A substantial part of this variation is explained by the use of different PBL‐height definitions in the schemes. The use of a standardized procedure in calculating the PBL height from common WRF output parameters, in particular the temperature gradient and the wind shear, leads to reduced differences between the different schemes and a closer correspondence with the FINO1 measurements. The study also reveals a very clear seasonal dependency of the atmospheric stability over Southern North Sea. During winter time, the marine atmospheric boundary layer is more or less neutral with several episodes of unstable periods. During spring and early summer, the occurrence of periods with very stable stratification becomes dominant with stable conditions up to 40–45% of the time when warm continental air is advected from the South. In general, the results of part II confirm again that the MYJ scheme performs slightly better than the others and can therefore be suggested as first choice for marine atmospheric boundary layer simulations without a priori information of atmospheric stability in the region of interest. Copyright © 2014 John Wiley & Sons, Ltd.

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A Method for Increasing the Turbulent Kinetic Energy in the Mellor–Yamada–Janjić Boundary-Layer Parametrization

Cited by 15 publications

References 31 publications

Structure of the planetary boundary layer over Southeast England: Modeling and measurements

Structure of the planetary boundary layer over Southeast England: Modeling and measurements

Analysis of Vertical Turbulent Heat Flux Limit in Stable Conditions with a Local Equilibrium, Turbulence Closure Model

Validation of boundary layer parameterization schemes in the Weather Research and Forecasting (WRF) model under the aspect of offshore wind energy applications—part II: boundary layer height and atmospheric stability

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