Connecting the failure of Ktheory inside and above vegetation canopies and ejectionsweep cycles by a large eddy simulation
Abstract
Parameterizations of biosphereatmosphere interaction processes in climate models and other hydrological applications require characterization of turbulent transport of momentum and scalars between vegetation canopies and the atmosphere, which is often modeled using a turbulent analogy to molecular diffusion processes. However, simple fluxgradient approaches (Ktheory) fail for canopy turbulence. One cause is turbulent transport by large coherent eddies at the canopy scale, which can be linked to sweepejection events, and bear signatures of nonlocal organized eddy motions. Ktheory, that parameterizes the turbulent flux or stress proportional to the local concentration or velocity gradient, fails to account for these nonlocal organized motions. The connection to sweepejection cycles and the local turbulent flux can be traced back to the turbulence triple moment $$\overline{C'W'W'}$$. In this work, we use largeeddy simulation to investigate the diagnostic connection between the failure of Ktheory and sweepejection motions. Analyzed schemes are quadrant analysis (QA) and a complete and incomplete cumulant expansion (CEM and ICEM) method. The latter approaches introduce a turbulence timescale in the modeling. Furthermore, we find that the momentum flux needs a different formulation for the turbulence timescale than the sensible heat flux. In conclusion, accounting for buoyancy in stratified conditions is also deemed to be important in addition to accounting for nonlocal events to predict the correct momentum or scalar fluxes.
 Authors:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Karlsruhe Inst. of Technology (KIT) (Germany). Inst. of Meteorology and Climate Research, Atmospheric Environmental Research (IMKIFU)
 Karlsruhe Inst. of Technology (KIT) (Germany). Inst. of Meteorology and Climate Research, Atmospheric Environmental Research (IMKIFU)
 Publication Date:
 Research Org.:
 Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
 Sponsoring Org.:
 USDOE; German Research Foundation (DFG)
 OSTI Identifier:
 1407897
 Report Number(s):
 LAUR1726916
Journal ID: ISSN 15588424; TRN: US1703062
 Grant/Contract Number:
 AC5206NA25396
 Resource Type:
 Journal Article: Accepted Manuscript
 Journal Name:
 Journal of Applied Meteorology and Climatology
 Additional Journal Information:
 Journal Name: Journal of Applied Meteorology and Climatology; Journal ID: ISSN 15588424
 Publisher:
 American Meteorological Society
 Country of Publication:
 United States
 Language:
 English
 Subject:
 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; Earth Sciences; Canopy turbulence; large eddy simulation; gradient  diffusion; sweep  ejection cycles
Citation Formats
Banerjee, Tirtha, De Roo, Frederik, and Mauder, Matthias. Connecting the failure of Ktheory inside and above vegetation canopies and ejectionsweep cycles by a large eddy simulation. United States: N. p., 2017.
Web. doi:10.1175/JAMCD160363.1.
Banerjee, Tirtha, De Roo, Frederik, & Mauder, Matthias. Connecting the failure of Ktheory inside and above vegetation canopies and ejectionsweep cycles by a large eddy simulation. United States. doi:10.1175/JAMCD160363.1.
Banerjee, Tirtha, De Roo, Frederik, and Mauder, Matthias. 2017.
"Connecting the failure of Ktheory inside and above vegetation canopies and ejectionsweep cycles by a large eddy simulation". United States.
doi:10.1175/JAMCD160363.1.
@article{osti_1407897,
title = {Connecting the failure of Ktheory inside and above vegetation canopies and ejectionsweep cycles by a large eddy simulation},
author = {Banerjee, Tirtha and De Roo, Frederik and Mauder, Matthias},
abstractNote = {Parameterizations of biosphereatmosphere interaction processes in climate models and other hydrological applications require characterization of turbulent transport of momentum and scalars between vegetation canopies and the atmosphere, which is often modeled using a turbulent analogy to molecular diffusion processes. However, simple fluxgradient approaches (Ktheory) fail for canopy turbulence. One cause is turbulent transport by large coherent eddies at the canopy scale, which can be linked to sweepejection events, and bear signatures of nonlocal organized eddy motions. Ktheory, that parameterizes the turbulent flux or stress proportional to the local concentration or velocity gradient, fails to account for these nonlocal organized motions. The connection to sweepejection cycles and the local turbulent flux can be traced back to the turbulence triple moment $\overline{C'W'W'}$. In this work, we use largeeddy simulation to investigate the diagnostic connection between the failure of Ktheory and sweepejection motions. Analyzed schemes are quadrant analysis (QA) and a complete and incomplete cumulant expansion (CEM and ICEM) method. The latter approaches introduce a turbulence timescale in the modeling. Furthermore, we find that the momentum flux needs a different formulation for the turbulence timescale than the sensible heat flux. In conclusion, accounting for buoyancy in stratified conditions is also deemed to be important in addition to accounting for nonlocal events to predict the correct momentum or scalar fluxes.},
doi = {10.1175/JAMCD160363.1},
journal = {Journal of Applied Meteorology and Climatology},
number = ,
volume = ,
place = {United States},
year = 2017,
month =
}

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