Characterizing and Constraining Uncertainty Associated with Surface and Boundary Layer Turbulent Fluxes in Simulations of Lake-Effect Snowfall

Abstract Lake-effect snow (LeS) storms are driven by strong turbulent surface layer (SL) and planetary boundary layer (PBL) fluxes of heat and moisture caused by the flow of cold air over relatively warm water. To investigate the sensitivity of simulated LeS to the parameterization of SL and PBL turbulence, high-resolution simulations of two major storms, downwind of Lakes Superior and Ontario, are conducted using the Weather Research and Forecasting Model. Multischeme and parameter sensitivity experiments are conducted. Measurements of overlake fluxes and downwind snowfall are used to evaluate the simulations. Consistent with previous studies, LeS is found to be strongly sensitive to SL and PBL parameterization choices. Simulated precipitation accumulations differ by up to a factor of 2 depending on the schemes used. Differences between SL schemes are the dominant source of this sensitivity. Parameterized surface fluxes of sensible and latent heat can each vary by over 100 W m−2 between SL schemes. The magnitude of these fluxes is correlated with the amount of downwind precipitation. Differences between PBL schemes play a secondary role, but have notable impacts on storm morphology. Many schemes produce credible simulations of overlake fluxes and downwind snowfall. However, the schemes that produce the largest surface fluxes produce fluxes and precipitation accumulations that are biased high relative to observations. For two SL schemes studied in detail, unrealistically large fluxes can be attributed to parameter choices: the neutral stability turbulent Prandtl number and the threshold friction velocity used for defining regimes in the overwater surface roughness calculation.

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Parameterization of fluxes over heterogeneous snow cover for GCMs

Annals of Glaciology ◽

10.3189/s0260305500013768 ◽

1997 ◽

Vol 25 ◽

pp. 38-41 ◽

Cited By ~ 2

Author(s):

Richard Essery

Keyword(s):

Boundary Layer ◽

Snow Cover ◽

Surface Fluxes ◽

Layer Model ◽

Boundary Layer Model ◽

Single Column ◽

Hadley Centre ◽

Heat And Moisture ◽

The Impact ◽

Tile Model

Fluxes of heat and moisture over heterogeneous snow cover are studied using a boundary-layer model. The performance of a “tile” model, suitable for calculating gridbox-average surface fluxes in a GCM, is assessed in comparison with the boundary-layer model. The impact of using a tile representation for heterogeneous snow cover in a single-column version of the Hadley Centre GCM is discussed.

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Integrating canopy and large-scale effects in the convective boundary-layer dynamics during the CHATS experiment

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-1623-2017 ◽

2017 ◽

Vol 17 (3) ◽

pp. 1623-1640 ◽

Cited By ~ 5

Author(s):

Metodija M. Shapkalijevski ◽

Huug G. Ouwersloot ◽

Arnold F. Moene ◽

Jordi Vilà-Guerau de Arrellano

Keyword(s):

Boundary Layer ◽

Latent Heat ◽

Convective Boundary Layer ◽

Friction Velocity ◽

Surface Fluxes ◽

Convective Boundary ◽

Diurnal Variability ◽

Drag Coefficients ◽

Boundary Layer Dynamics ◽

The Impact

Abstract. By characterizing the dynamics of a convective boundary layer above a relatively sparse and uniform orchard canopy, we investigated the impact of the roughness-sublayer (RSL) representation on the predicted diurnal variability of surface fluxes and state variables. Our approach combined numerical experiments, using an atmospheric mixed-layer model including a land-surface-vegetation representation, and measurements from the Canopy Horizontal Array Turbulence Study (CHATS) field experiment near Dixon, California. The RSL is parameterized using an additional factor in the standard Monin–Obukhov similarity theory flux-profile relationships that takes into account the canopy influence on the atmospheric flow. We selected a representative case characterized by southerly wind conditions to ensure well-developed RSL over the orchard canopy. We then investigated the sensitivity of the diurnal variability of the boundary-layer dynamics to the changes in the RSL key scales, the canopy adjustment length scale, Lc, and the β = u*/|U| ratio at the top of the canopy due to their stability and dependence on canopy structure. We found that the inclusion of the RSL parameterization resulted in improved prediction of the diurnal evolution of the near-surface mean quantities (e.g. up to 50 % for the wind velocity) and transfer (drag) coefficients. We found relatively insignificant effects on the modelled surface fluxes (e.g. up to 5 % for the friction velocity, while 3 % for the sensible and latent heat), which is due to the compensating effect between the mean gradients and the drag coefficients, both of which are largely affected by the RSL parameterization. When varying Lc (from 10 to 20 m) and β (from 0.25 to 0.4 m), based on observational evidence, the predicted friction velocity is found to vary by up to 25 % and the modelled surface-energy fluxes (sensible heat, SH, and latent heat of evaporation, LE) vary up to 2 and 9 %. Consequently, the boundary-layer height varies up to 6 %. Furthermore, our analysis indicated that to interpret the CHATS measurements above the canopy, the contributions of non-local effects such as entrainment, subsidence and the advection of heat and moisture over the CHATS site need to be taken into account.

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Evaluation of an E–ε and Three Other Boundary Layer Parameterization Schemes in the WRF Model over the Southeast Pacific and the Southern Great Plains

Monthly Weather Review ◽

10.1175/mwr-d-19-0084.1 ◽

2020 ◽

Vol 148 (3) ◽

pp. 1121-1145 ◽

Cited By ~ 2

Author(s):

Chunxi Zhang ◽

Yuqing Wang ◽

Ming Xue

Keyword(s):

Boundary Layer ◽

Great Plains ◽

Wrf Model ◽

Weather Research And Forecasting ◽

Liquid Water Path ◽

Southern Great Plains ◽

Southeast Pacific ◽

Tke Dissipation Rate ◽

Pbl Parameterization ◽

The University

Abstract To accurately simulate the atmospheric state within the planetary boundary layer (PBL) by PBL parameterization scheme in different regions with their dominant weather/climate regimes is important for global/regional atmospheric models. In this study, we introduce the turbulence kinetic energy (TKE) and TKE dissipation rate (ε) based 1.5-order closure PBL parameterization (E–ε, EEPS) in the Weather Research and Forecasting (WRF) Model. The performances of the newly implemented EEPS scheme and the existing Yonsei University (YSU) scheme, the University of Washington (UW) scheme, and Mellor–Yamada–Nakanishi–Niino (MYNN) scheme are evaluated over the stratocumulus dominated southeast Pacific (SEP) and over the Southern Great Plains (SGP) where strong PBL diurnal variation is common. The simulations by these PBL parameterizations are compared with various observations from two field campaigns: the Variability of American Monsoon Systems Project (VAMOS) Ocean–Cloud–Atmosphere–Land Study (VOCALS) in 2008 over the SEP and the Land–Atmosphere Feedback Experiment (LAFE) in 2017 over the SGP. Results show that the EEPS and YSU schemes perform comparably over both regions, while the MYNN scheme performs differently in many aspects, especially over the SEP. The EEPS (MYNN) scheme slightly (significantly) underestimates liquid water path over the SEP. Compared with observations, the UW scheme produces the best PBL height over the SEP. The MYNN produces too high PBL height over the western part of the SEP while both the YSU and EEPS schemes produce too low PBL and cloud-top heights. The differences among the PBL schemes in simulating the PBL features over the SGP are relatively small.

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Physical Processes

An Introduction to Global Spectral Modeling ◽

10.1093/oso/9780195094732.003.0010 ◽

1998 ◽

Author(s):

T. N. Krishnamurti ◽

H. S. Bedi ◽

V. M. Hardiker

Keyword(s):

Boundary Layer ◽

Energy Balance ◽

Surface Energy ◽

Surface Energy Balance ◽

Weather Prediction ◽

Surface Fluxes ◽

Physical Processes ◽

Numerical Weather ◽

Spectral Models ◽

Heat And Moisture

In this chapter we present some of the physical processes that are used in numerical weather prediction modeling. Grid-point models, based on finite differences, and spectral models both generally treat the physical processes in the same manner. The vertical columns above the horizontal grid points (the transform grid for the spectral models) are the ones along which estimates of the effects of the physical processes are made. In this chapter we present a treatment of the planetary boundary layer, including a discussion on the surface similarity theory. Also covered is the cumulus parameterization problem in terms of the Kuo scheme and the Arakawa- Schubert sheme. Large-scale condensation and radiative transfer in clear and cloudy skies are the final topics reviewed. There are at least three types of fluxes that one deals with, namely momentum, sensible heat, and moisture. Furthermore, one needs to examine separately the land and ocean regions. In this section we present the socalled bulk aerodynamic methods as well as the similarity analysis approach for the estimation of the surface fluxes. The radiation code in a numerical weather prediction model is usually coupled to the calculation of the surface energy balance. This will be covered later in Section 8.5.6. This surface energy balance is usually carried out over land areas, where one balances the net radiation against the surface fluxes of heat and moisture for the determination of soil temperature. Over oceans, the sea-surface temperatures are prescribed where the surface energy balance is implicit. Thus it is quite apparent that what one does in the parameterization of the planetary boundary layer has to be integrated with the radiative parameterization in a consistent manner.

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Integrating canopy and large-scale atmospheric effects in convective boundary-layer dynamics during CHATS experiment

10.5194/acp-2016-714 ◽

2016 ◽

Author(s):

Metodija M. Shapkalijevski ◽

G. Huug Ouwersloot ◽

F. Arnold Moene ◽

Jordi Vilà‐Guerau Arellano

Keyword(s):

Boundary Layer ◽

Convective Boundary Layer ◽

Friction Velocity ◽

Surface Fluxes ◽

Atmospheric Effects ◽

Convective Boundary ◽

Diurnal Variability ◽

Drag Coefficients ◽

Boundary Layer Dynamics ◽

The Impact

Abstract. By characterizing the dynamics of a convective boundary layer above a relatively sparse and uniform orchard canopy, we investigated the impact of the roughness sublayer (RSL) representation on the predicted diurnal variability of surface fluxes and state variables. Our approach combined numerical experiments, using an atmospheric mixed-layer model including a land surface-vegetation representation, and measurements from the Canopy Horizontal Array Turbulence Study (CHATS) field experiment near Dixon, California. The RSL is parameterized using an additional factor in the standard Monin-Obukhov Similarity Theory flux-profile relationships that takes into account the canopy’s influence on the atmospheric flow. We selected a representative case characterised by southerly wind conditions to ensure well-developed RSL over the orchard canopy. We then investigated the sensitivity of the diurnal variability of the boundary-layer dynamics to the changes in the RSL key scales, the canopy adjustment length scale, Lc, and the β = u*/|U| ratio at the top of the canopy, due to their stability and dependence on canopy structure. We found that the inclusion of the RSL parameterisation resulted in improved prediction of the diurnal evolution of the near-surface mean quantities (e.g. up to 50 % for the wind velocity) and transfer (drag) coefficients. We found relatively insignificant effects on the modelled surface fluxes (e.g. up to 5 % for the friction velocity, while 3 % for the sensible and latent heat), which is due to the compensating effect between the mean gradients and the drag coefficients, which are both largely affected by the RSL parameterisation. When varying Lc (from 10 to 20 m) and β (from 0.25 to 0.4), based on observational evidence, the predicted friction velocity is found to vary by up to 25 % and the modeled surface energy fluxes (SH and LE) vary up to 2 % and 9 %, respectively. Consequently, the boundary-layer height varies up to 6 %. Furthermore, our analysis indicated that to interpret the CHATS measurements above the canopy, the contributions of non-local effects such as entrainment, subsidence and the advection of heat and moisture over the CHATS site need to be taken into account.

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Observations and WRF simulations of fog events at the Spanish Northern Plateau

Advances in Science and Research ◽

10.5194/asr-8-11-2012 ◽

2012 ◽

Vol 8 (1) ◽

pp. 11-18 ◽

Cited By ~ 34

Author(s):

C. Román-Cascón ◽

C. Yagüe ◽

M. Sastre ◽

G. Maqueda ◽

F. Salamanca ◽

...

Keyword(s):

Boundary Layer ◽

Surface Layer ◽

Weather Prediction ◽

Liquid Water Content ◽

Weather Research And Forecasting ◽

Mean Square ◽

Gravitational Settling ◽

Pbl Scheme ◽

Pbl Parameterization

Abstract. The prediction of fogs is one of the processes not well reproduced by the Numerical Weather Prediction (NWP) models. In particular, the role of turbulence in the formation or dissipation of fogs is one of the physical processed not well understood, and therefore, not well parameterized by the NWP models. Observational analysis of three different periods with fogs at the Spanish Northern Plateau has been carried out. These periods have also been simulated with the Weather Research and Forecasting (WRF) numerical model and their results have been compared to observations. The study includes a comparison of the skill of different planetary boundary layer (PBL) parameterizations, surface layer schemes and a test of the gravitational settling of clouds/fogs droplets option. A statistical analysis of this comparison has been evaluated in order to study differences between the periods and between the various parameterizations used. The model results for each PBL parameterization were different, depending on the studied period, due to differences in the features of each fog. This fact made it difficult to obtain generalized conclusions, but allowed us to determine which parameterization performed better for each case. In general, judging from the models results of liquid water content (LWC), none of the PBL schemes were able to correctly simulate the fogs, being Mellor-Yamada Nakanishi and Niino (MYNN) 2.5 level PBL scheme the best one in most of the cases. This conclusion is also supported by the root mean square error (RMSE) calculated for different meteorological variables.

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Parameterization of fluxes over heterogeneous snow cover for GCMs

Annals of Glaciology ◽

10.1017/s0260305500013768 ◽

1997 ◽

Vol 25 ◽

pp. 38-41 ◽

Cited By ~ 1

Author(s):

Richard Essery

Keyword(s):

Boundary Layer ◽

Snow Cover ◽

Surface Fluxes ◽

Layer Model ◽

Boundary Layer Model ◽

Single Column ◽

Hadley Centre ◽

Heat And Moisture ◽

The Impact ◽

Tile Model

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Evaluation of the Weather Research and Forecasting Model in the Durance Valley Complex Terrain during the KASCADE Field Campaign

Journal of Applied Meteorology and Climatology ◽

10.1175/jamc-d-15-0258.1 ◽

2016 ◽

Vol 55 (4) ◽

pp. 861-882 ◽

Cited By ~ 19

Author(s):

Peter Christiaan Kalverla ◽

Gert-Jan Duine ◽

Gert-Jan Steeneveld ◽

Thierry Hedde

Keyword(s):

Boundary Layer ◽

Heat Flux ◽

Soil Moisture ◽

Land Surface ◽

Soil Moisture Content ◽

Sensible Heat Flux ◽

Weather Research And Forecasting ◽

Sensible Heat ◽

Initial Soil ◽

Pbl Parameterization

AbstractIn the winter of 2012/13, the Katabatic Winds and Stability over Cadarache for the Dispersion of Effluents (KASCADE) observational campaign was carried out in southeastern France to characterize the wind and thermodynamic structure of the (stable) planetary boundary layer (PBL). Data were collected with two micrometeorological towers, a sodar, a tethered balloon, and radiosoundings. Here, this dataset is used to evaluate the representation of the boundary layer in the Weather Research and Forecasting (WRF) Model. In general, it is found that diurnal temperature range (DTR) is largely underestimated, there is a strong negative bias in both longwave radiation components, and evapotranspiration is overestimated. An illustrative case is subjected to a thorough model-physics evaluation. First, five PBL parameterization schemes and two land surface schemes are employed. A marginal sensitivity to PBL parameterization is found, and the sophisticated Noah land surface model represents the extremes in skin temperature better than does a more simple thermal diffusion scheme. In a second stage, sensitivity tests for land surface–atmosphere coupling (through parameterization of z0h/z0m), initial soil moisture content, and radiation parameterization were performed. Relatively strong surface coupling and low soil moisture content result in a larger sensible heat flux, deeper PBL, and larger DTR. The larger sensible heat flux is not supported by the observations, however. It turns out that, for the selected case, a combination of subsidence and warm-air advection is not accurately simulated, but this inaccuracy cannot fully explain the discrepancies found in the WRF simulations. The results of the sensitivity analysis reiterate the important role of initial soil moisture values.

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