Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain
Abstract
The assumption of subgrid scale (SGS) horizontal homogeneity within a model grid cell, which forms the basis of SGS turbulence closures used by mesoscale models, becomes increasingly tenuous as grid spacing is reduced to a few kilometers or less, such as in many emerging highresolution applications. Herein, we use the turbulence kinetic energy (TKE) budget equation to study the spatiotemporal variability in two types of terrain—complex (Columbia Basin Wind Energy Study [CBWES] site, northeastern Oregon) and flat (ScaledWind Farm Technologies [SWiFT] site, west Texas) using the Weather Research and Forecasting (WRF) model. In each case sixnested domains (three domains each for mesoscale and largeeddy simulation [LES]) are used to downscale the horizontal grid spacing from 10 km to 10 m using the WRF model framework. The model output was used to calculate the values of the TKE budget terms in vertical and horizontal planes as well as the averages of grid cells contained in the four quadrants (a quarter area) of the LES domain. The budget terms calculated along the planes and the mean profile of budget terms show larger spatial variability at CBWES site than at the SWiFT site. The contribution of the horizontal derivative of the shear productionmore »
 Authors:
 Pacific Northwest National Laboratory, Richland, Washington
 National Center for Atmospheric Research, Boulder, Colorado
 Lawrence Livermore National Laboratory, Livermore, California
 Sandia National Laboratories, Albuquerque, New Mexico
 Publication Date:
 Research Org.:
 Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
 Sponsoring Org.:
 USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind Energy Technologies Office (EE4WE)
 OSTI Identifier:
 1416688
 Report Number(s):
 PNNLSA125867
Journal ID: ISSN 15588424; WW0600000
 DOE Contract Number:
 AC0576RL01830
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Applied Meteorology and Climatology; Journal Volume: 56; Journal Issue: 12
 Country of Publication:
 United States
 Language:
 English
 Subject:
 Spatiotemporal; convective boundary layer; subgrid scale; SGS; turbulence kinetic energy; TKE
Citation Formats
Rai, Raj K., Berg, Larry K., Pekour, Mikhail, Shaw, William J., Kosovic, Branko, Mirocha, Jeffrey D., and Ennis, Brandon L. Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain. United States: N. p., 2017.
Web. doi:10.1175/JAMCD170124.1.
Rai, Raj K., Berg, Larry K., Pekour, Mikhail, Shaw, William J., Kosovic, Branko, Mirocha, Jeffrey D., & Ennis, Brandon L. Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain. United States. doi:10.1175/JAMCD170124.1.
Rai, Raj K., Berg, Larry K., Pekour, Mikhail, Shaw, William J., Kosovic, Branko, Mirocha, Jeffrey D., and Ennis, Brandon L. 2017.
"Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain". United States.
doi:10.1175/JAMCD170124.1.
@article{osti_1416688,
title = {Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain},
author = {Rai, Raj K. and Berg, Larry K. and Pekour, Mikhail and Shaw, William J. and Kosovic, Branko and Mirocha, Jeffrey D. and Ennis, Brandon L.},
abstractNote = {The assumption of subgrid scale (SGS) horizontal homogeneity within a model grid cell, which forms the basis of SGS turbulence closures used by mesoscale models, becomes increasingly tenuous as grid spacing is reduced to a few kilometers or less, such as in many emerging highresolution applications. Herein, we use the turbulence kinetic energy (TKE) budget equation to study the spatiotemporal variability in two types of terrain—complex (Columbia Basin Wind Energy Study [CBWES] site, northeastern Oregon) and flat (ScaledWind Farm Technologies [SWiFT] site, west Texas) using the Weather Research and Forecasting (WRF) model. In each case sixnested domains (three domains each for mesoscale and largeeddy simulation [LES]) are used to downscale the horizontal grid spacing from 10 km to 10 m using the WRF model framework. The model output was used to calculate the values of the TKE budget terms in vertical and horizontal planes as well as the averages of grid cells contained in the four quadrants (a quarter area) of the LES domain. The budget terms calculated along the planes and the mean profile of budget terms show larger spatial variability at CBWES site than at the SWiFT site. The contribution of the horizontal derivative of the shear production term to the total production shear was found to be 45% and 15% of the total shear, at the CBWES and SWiFT sites, respectively, indicating that the horizontal derivatives applied in the budget equation should not be ignored in mesoscale model parameterizations, especially for cases with complex terrain with <10 km scale.},
doi = {10.1175/JAMCD170124.1},
journal = {Journal of Applied Meteorology and Climatology},
number = 12,
volume = 56,
place = {United States},
year = 2017,
month =
}

Comparison of Measured and Numerically Simulated Turbulence Statistics in a Convective Boundary Layer Over Complex Terrain
High resolution numerical simulation can provide insight into important physical processes that occur within the planetary boundary layer (PBL). The present work employs large eddy simulation (LES) using the Weather Forecasting and Research (WRF) model, with the LES domain nested within mesoscale simulation, to simulate real conditions in the convective PBL over an area of complex terrain. A multiple nesting approach has been used to downsize the grid spacing from 12.15 km (mesoscale) to 0.03 km (LES). A careful selection of grid spacing in the WRF Meso domain has been conducted to minimize artifacts in the WRFLES solutions. The WRFLESmore » 
Convective boundary layer budgets of moisture and sensible heat over an unstressed prairie
An evaluation of convective boundary layer budgets of sensible heat and moisture were examined for two days over the unstressed vegetation of the tallgrass Konza National Prairie. In addition to the budget evaluation the study had these goals: to estimate the areaaverage surface fluxes and compare them to independent, groundbased measurements, to estimate the near surface evaporative fraction, and to compare different evaluations of the ratio of surface to inversion fluxes, i.e., the entrainment parameter. The budget analyses indicate that vertical and horizontal advection were significant terms in the budget and cannot be ignored. 26 refs. 
Horizontal heat fluxes over complex terrain computed using a simple mixedlayer model and a numerical model
The thermally induced local circulation over a periodic valley is simulated by a twodimensional numerical model that doesnot include condensational processes. During the daytime of a clear, calm day, heat is transported from the mountainous region to the valley area by anabatic wind and its return flow. The specific humidity is, however, transported in an inverse manner. The horizontal exchange rate of sensible heat has a horizontal scale similarity, as long as the horizontal scale is less than a critical width of about 100 km. The sensible heat accumulated in an atmospheric column over an arbitrary point can be estimatedmore » 
Mesoscale boundary layer evolution over complex terrain. Part I: Numerical simulation of the diurnal cycle
The continuous development of a meso..beta..scale boundary layer over sloping terrain upwind of a high mountain barrier was simulated through a complete diurnal cycle using a nonhydrostatic boundarylayer model. The simulation detailed the evolution of a 500800m deep nocturnal boundary layer containing 13 m s/sup 1/ thermal circulations in the region upwind of a high ridge. Shear between the 5 m s/sup 1/ gradient level winds above the boundary layer and the mesoscale thermal circulations maintained the turbulent mixing of cold air upward against the stable stratification. The nocturnal boundary layer is replaced the following morning by a growing convectivemore »