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Title: The KPP boundary layer scheme for the ocean: revisiting its formulation and benchmarking one-dimensional simulations relative to LES

Abstract

We evaluate the Community ocean Vertical Mixing (CVMix) project version of the K-profile parameterization (KPP) for modeling upper ocean turbulent mixing. For this purpose, one-dimensional KPP simulations are compared across a suite of oceanographically relevant regimes against horizontally averaged large eddy simulations (LES). We find the standard configuration of KPP consistent with LES across many forcing regimes, supporting its physical basis. Our evaluation also motivates recommendations for KPP “best practices” within ocean circulation models, and identifies areas where further research is warranted. The original treatment of KPP recommends the matching of interior diffusivities and their gradients to the KPP predicted values computed in the ocean surface boundary layer (OSBL). However, we find that difficulties in representing derivatives of rapidly changing diffusivities near the base of the OSBL can lead to loss of simulation fidelity. To mitigate this difficulty, we propose and evaluate two computationally simpler approaches: (1) match to the internal predicted diffusivity alone, (2) set the KPP diffusivity to zero at the OSBL base. We find the KPP entrainment buoyancy flux to be sensitive to vertical grid resolution and details of how to diagnose the KPP boundary layer depth. We modify the KPP turbulent shear velocity parameterization to reducemore » resolution dependence. Additionally, an examination of LES vertical turbulent scalar flux budgets shows that the KPP parameterized non-local tracer flux is incomplete due to the assumption that it solely redistributes the surface tracer flux. This result motivates further studies of the non-local flux parameterization.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [2];  [3];  [3]; ORCiD logo [3];  [2];  [1];  [4]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. NOAA Geophysical Fluid Dynamics Lab., Princeton, NJ (United States); Princeton Univ., NJ (United States). Program in Atmospheric and Oceanic Sciences
  3. National Center for Atmospheric Research, Boulder, CO (United States). Climate and Global Dynamics Lab.
  4. Leibniz Inst. for Baltic Sea Research, Rostock (Germany)
Publication Date:
Research Org.:
Oak Ridge National Laboratory, Oak Ridge Leadership Computing Facility (OLCF); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); National Center for Atmospheric Research, Boulder, CO (United States); Princeton Univ., NJ (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); Princeton Univ. (United States)
OSTI Identifier:
1480901
Alternate Identifier(s):
OSTI ID: 1475346; OSTI ID: 1480902
Report Number(s):
LA-UR-16-26992
Journal ID: ISSN 1942-2466
Grant/Contract Number:  
AC52-06NA25396; AC05-00OR22725; SC0012605
Resource Type:
Published Article
Journal Name:
Journal of Advances in Modeling Earth Systems
Additional Journal Information:
Journal Name: Journal of Advances in Modeling Earth Systems; Journal ID: ISSN 1942-2466
Publisher:
American Geophysical Union (AGU)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; KPP; vertical mixing; ocean surface boundary layer; parameterization; ocean model

Citation Formats

Van Roekel, Luke, Adcroft, Alistair, Danabasoglu, Gokhan, Griffies, Stephen M., Kauffman, Brian, Large, William, Levy, Michael, Reichl, Brandon G., Ringler, Todd, and Schmidt, Martin. The KPP boundary layer scheme for the ocean: revisiting its formulation and benchmarking one-dimensional simulations relative to LES. United States: N. p., 2018. Web. doi:10.1029/2018MS001336.
Van Roekel, Luke, Adcroft, Alistair, Danabasoglu, Gokhan, Griffies, Stephen M., Kauffman, Brian, Large, William, Levy, Michael, Reichl, Brandon G., Ringler, Todd, & Schmidt, Martin. The KPP boundary layer scheme for the ocean: revisiting its formulation and benchmarking one-dimensional simulations relative to LES. United States. doi:10.1029/2018MS001336.
Van Roekel, Luke, Adcroft, Alistair, Danabasoglu, Gokhan, Griffies, Stephen M., Kauffman, Brian, Large, William, Levy, Michael, Reichl, Brandon G., Ringler, Todd, and Schmidt, Martin. Mon . "The KPP boundary layer scheme for the ocean: revisiting its formulation and benchmarking one-dimensional simulations relative to LES". United States. doi:10.1029/2018MS001336.
@article{osti_1480901,
title = {The KPP boundary layer scheme for the ocean: revisiting its formulation and benchmarking one-dimensional simulations relative to LES},
author = {Van Roekel, Luke and Adcroft, Alistair and Danabasoglu, Gokhan and Griffies, Stephen M. and Kauffman, Brian and Large, William and Levy, Michael and Reichl, Brandon G. and Ringler, Todd and Schmidt, Martin},
abstractNote = {We evaluate the Community ocean Vertical Mixing (CVMix) project version of the K-profile parameterization (KPP) for modeling upper ocean turbulent mixing. For this purpose, one-dimensional KPP simulations are compared across a suite of oceanographically relevant regimes against horizontally averaged large eddy simulations (LES). We find the standard configuration of KPP consistent with LES across many forcing regimes, supporting its physical basis. Our evaluation also motivates recommendations for KPP “best practices” within ocean circulation models, and identifies areas where further research is warranted. The original treatment of KPP recommends the matching of interior diffusivities and their gradients to the KPP predicted values computed in the ocean surface boundary layer (OSBL). However, we find that difficulties in representing derivatives of rapidly changing diffusivities near the base of the OSBL can lead to loss of simulation fidelity. To mitigate this difficulty, we propose and evaluate two computationally simpler approaches: (1) match to the internal predicted diffusivity alone, (2) set the KPP diffusivity to zero at the OSBL base. We find the KPP entrainment buoyancy flux to be sensitive to vertical grid resolution and details of how to diagnose the KPP boundary layer depth. We modify the KPP turbulent shear velocity parameterization to reduce resolution dependence. Additionally, an examination of LES vertical turbulent scalar flux budgets shows that the KPP parameterized non-local tracer flux is incomplete due to the assumption that it solely redistributes the surface tracer flux. This result motivates further studies of the non-local flux parameterization.},
doi = {10.1029/2018MS001336},
journal = {Journal of Advances in Modeling Earth Systems},
number = ,
volume = ,
place = {United States},
year = {2018},
month = {9}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
DOI: 10.1029/2018MS001336

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Cited by: 4 works
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