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
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 | Implement supercycling advection of ocean passive tracers |
| 2.Owner | Katherine Smith Andrew Bradley Mathew Maltrud |
| 3.Created | Aug 13, 2021 |
| 4.Equ | |
| 5.Ver | |
| 6.Perf | |
| 7.Val | |
| 8.Approver | |
| 9.Approved Date | |
| V2.0 |
Title: Ocean Passive Tracer Supercycling
Requirements and Design
E3SM CBGC Group
Date: 08/13/2021
Summary
Transport of ocean BGC tracers is ~70% of the cost of MPAS-O (when BGC tracers are turned on). We hypothesize that the advection step of the BGC tracer transport can be increased to 2-3 times that of the baroclinic time step with little loss in accuracy, thereby decreasing the overall cost of transport for BGC tracers in the ocean. We propose to implement a tracer-consistent, mass-conserving supercycling of the advection of all passive tracers in MPAS-O. If possible, options to (i) supercycle the tracer advection at time-steps larger than the sea-ice coupling interval (referred to as supercycling-over-coupling [SOC]) and (ii) subcycle the BGC reactions will be included. We propose to validate the scheme in MPAS by testing in a G-case configuration (ocean + ice), comparing mass conservation of carbon within the ocean, and comparing monthly averages of BGC tracer outputs.