The Design Document page provides a description of the algorithms, implementation and planned testing including unit, verification, validation and performance testing. Please read Step 1.3 Performance Expectations that explains feature documentation requirements from the performance group point of view.

Design Document

Click here for instructions to fill up the table below ......

The first table in Design Document gives overview of this document, from this info the Design Documents Overview page is automatically created.

In the overview table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation

Equations: Document the equations that are being solved and describe algorithms
Verification Plans: Define tests that will be run to show that implementation is correct and robust. Involve unit tests to cover range of inputs as well as benchmarks.
Performance expectations: Explain the expected performance impact from this development
Validation Plans: Document what process-based, stand-alone component, and coupled model runs will be performed, and with what metrics will be used to assess validity

Use the symbols below (copy and paste) to indicate if the section is in progress or done or not started.

In the table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation, - competed, - in progress, - not done

Overview table for the owner and an approver of this feature

1.Description	Langmuir turbulence parameterization
2.Owner	Qing Li (Unlicensed)
3.Created	07 Jun 2019
4.Equ
5.Ver
6.Perf
7.Val
8.Approver
9.Approved Date

Click here for Table of Contents ...

Table of Contents

Title: Langmuir Turbulence Parameterization

Requirements and Design

E3SM Water Cycle Group

Date: 07 Jun 2019

Summary

Ocean surface waves are known to affect ocean surface boundary layer (OSBL) vertical mixing. Langmuir turbulence is one important mechanism by which ocean surface waves interact with boundary layer turbulence. This new feature includes parameterizations of two effects of Langmuir turbulence: (1) Langmuir enhanced vertical mixing within the OSBL; (2) Langmuir enhanced entrainment at the base of OSBL, via CVMix. Ocean surface wave information is required for the parameterization, which normally requires coupling with an ocean surface wave model (e.g., WAVEWATCH III). A simple solution with wave parameters approximated from surface wind using empirical wave spectrum is provided. The Langmuir turbulence parameterization generally makes the ocean surface mixed layer deeper, especially in the extratropical regions (e.g., Southern Ocean). As a result of stronger OSBL vertical mixing, subsurface layer is generally warmer.

Requirements

Requirement: Parameterizing effects of Langmuir turbulence on ocean surface vertical mixing

Date last modified: 07 Jun 2019
Contributors: Qing Li (Unlicensed)

Ocean surface boundary vertical mixing should be enhanced in the presence of Langmuir turbulence.

Requirement: Wave parameters

Date last modified: 07 Jun 2019
Contributors: Qing Li (Unlicensed)

The Langmuir turbulence parameterization requires wave parameters such as variants of Langmuir number, which are computed from Stokes drift profile and ocean surface friction velocity. This normally requires coupling with an ocean surface wave model such as WAVEWATCH III.

Algorithmic Formulations

Design solution: Langmuir turbulence parameterization via CVMix

Date last modified: 07 Jun 2019
Contributors: Qing Li (Unlicensed)

The formulations of the Langmuir turbulence parameterization adopted here are detailed in Li et al., 2016 and Li and Fox-Kemper, 2017, which modify KPP (Large et al., 1994, Van Roekel et al., 2018) to include the effects of Langmuir turbulence. In particular, two effects of Langmuir turbulence are considered here:

Langmuir enhanced vertical mixing within the OSBL, which is parameterized by applying an Langmuir number-dependent enhancement factor to the turbulent velocity scale in KPP following the scaling derived from large eddy simulation (LES) study by Van Roekel et al., 2012.
Langmuir enhanced entrainment at the base of OSBL, which is parameterized by modifying the bulk Richardson number in KPP using the scaling of entrainment buoyancy flux derived from LES of Li and Fox-Kemper, 2017.

Design solution: Approximation of wave parameters from empirical wave spectrum

Date last modified: 07 Jun 2019
Contributors: Qing Li (Unlicensed)

A simple solution to approximate wave parameters required by the Langmuir turbulence parameterization is provided here, which estimates the Stokes drift profile from 10-meter wind using empirical wave spectrum and some assumptions of the swell statistics following Li et al., 2017.

Design and Implementation

Implementation: Modifications to CVMix

Date last modified: 07 Jun 2019
Contributors: Qing Li (Unlicensed)

The modifications to KPP to include the Langmuir turbulence parameterization are implemented in CVMix (tag v0.94b-beta or later). Additional MPAS-Ocean namelist entries to activate the options are implemented:

config_cvmix_kpp_langmuir_mixing_opt: Options for Langmuir-enhanced vertical mixing. Valid options: 'NONE', 'LWF16'
config_cvmix_kpp_langmuir_entrainment_opt: Options for Langmuir-enhanced entrainment. Valid options: 'NONE', 'LWF16', 'LF17'
config_cvmix_kpp_use_theory_wave: Use empirical wave spectrum to approximate wave parameters if set to .true.

Planned Verification and Unit Testing

Verification and Unit Testing: short-desciption-of-testing-here

Date last modified:
Contributors: (add your name to this list if it does not appear)

How will XXX be tested? i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?

Planned Validation Testing

Validation Testing: short-desciption-of-testing-here

Date last modified:
Contributors: (add your name to this list if it does not appear)

How will XXX be tested? What observational or other dataset will be used? i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?

Planned Performance Testing

Performance Testing: short-desciption-of-testing-here

Date last modified:
Contributors: (add your name to this list if it does not appear)

How will XXX be tested? i.e. how will be we know when we have met requirement XXX. Will these unit tests be included in the ongoing going forward?

Browser not supported