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Title: Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain

Abstract

The assumption of sub-grid 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 high-resolution applications. Herein, we use the turbulence kinetic energy (TKE) budget equation to study the spatio-temporal variability in two types of terrain—complex (Columbia Basin Wind Energy Study [CBWES] site, north-eastern Oregon) and flat (ScaledWind Farm Technologies [SWiFT] site, west Texas) using the Weather Research and Forecasting (WRF) model. In each case six-nested domains (three domains each for mesoscale and large-eddy 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 » 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.« less

Authors:
 [1];  [1];  [1];  [1];  [2];  [3];  [4]
  1. Pacific Northwest National Laboratory, Richland, Washington
  2. National Center for Atmospheric Research, Boulder, Colorado
  3. Lawrence Livermore National Laboratory, Livermore, California
  4. 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 (EE-4WE)
OSTI Identifier:
1416688
Report Number(s):
PNNL-SA-125867
Journal ID: ISSN 1558-8424; WW0600000
DOE Contract Number:  
AC05-76RL01830
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:
Spatio-temporal; convective boundary layer; sub-grid 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/JAMC-D-17-0124.1.
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/JAMC-D-17-0124.1.
Rai, Raj K., Berg, Larry K., Pekour, Mikhail, Shaw, William J., Kosovic, Branko, Mirocha, Jeffrey D., and Ennis, Brandon L. Fri . "Spatiotemporal Variability of Turbulence Kinetic Energy Budgets in the Convective Boundary Layer over Both Simple and Complex Terrain". United States. doi:10.1175/JAMC-D-17-0124.1.
@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 sub-grid 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 high-resolution applications. Herein, we use the turbulence kinetic energy (TKE) budget equation to study the spatio-temporal variability in two types of terrain—complex (Columbia Basin Wind Energy Study [CBWES] site, north-eastern Oregon) and flat (ScaledWind Farm Technologies [SWiFT] site, west Texas) using the Weather Research and Forecasting (WRF) model. In each case six-nested domains (three domains each for mesoscale and large-eddy 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/JAMC-D-17-0124.1},
journal = {Journal of Applied Meteorology and Climatology},
number = 12,
volume = 56,
place = {United States},
year = {Fri Dec 01 00:00:00 EST 2017},
month = {Fri Dec 01 00:00:00 EST 2017}
}