W14: Alternative ocean surface flux schemes Design Document

Owned by Kai Zhang
Last updated: Aug 09, 2019 by Jack Reeves Eyre (Unlicensed)
2 min read

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

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In the 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

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Overview table for the owner and an approver of this feature

1.Description

Alternative ocean surface flux
2.Owner
Kai Zhang, Jack Reeves Eyre (Unlicensed)
3.Created
4.Equ(tick)
5.Ver(tick)
6.Perf(tick)
7.Val(tick)
8.Approver
9.Approved Date
V2.0
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Table of Contents

Title: Alternative ocean surface flux schemes

Requirements and Design

Date: 

Summary

Two alternative ocean surface flux schemes are implemented in E3SM in order to better simulate the heat and moisture fluxes over the ocean.


Algorithmic Formulations

The first scheme is the COAREv3.0 scheme that is based on Fairall et al (2003). This scheme was previously implemented in NorESM and it showed positive impacts on the climate. The second scheme is the UA flux scheme that is based on Zeng et al. (1998). See slide 1 in PowerPoint below for summary table.


Design and Implementation

Text below is copied from Jack's page.

PR: https://github.com/E3SM-Project/E3SM/tree/jackreeveseyre/cime/alternate_surface_flux

  1. Default scheme (ocn_surface_flux_scheme = 0)
  2. COARE (ocn_surface_flux_scheme = 1)
  3. UA scheme (ocn_surface_flux_scheme = 2)

To turn on the UA scheme add the following to user_nl_cpl:

ocn_surface_flux_scheme = 2

or add to your run script:

cd $CASEROOT
 
cat << EOF >> user_nl_cpl
  ocn_surface_flux_scheme = 2
EOF

This flag defaults to 0 (E3SMv1 scheme; Large and Pond etc.) and can also take value 1 (COARE v3.0).

Verification and Unit Testing 


Validation

Atmosphere-only (5yr) simulations were performed and evaluated against observation. Details can be found at:


/wiki/spaces/EWCG/pages/942342153

/wiki/spaces/EWCG/pages/976519868

Performance Testing 

No significant changes in model performance.