Oceananigans Coupling

[LenkaNovak]

(WIP!)

The Climate Modeling Alliance

Software Design Issue 📜

Purpose

• minimal coupling of Clima Ocean and ClimaCore-based models at ~1 deg resolution on cubed sphere meshes, demonstrating the required interfaces and coupler functionality for CMIP.

• (ideas from Ocean-Atmos Sequential Coupling (preliminary plan) #157)

Cost/Benefits/Risks

People and Personnel

Components

• generalised interface for flux exchange (using ideas from Generalized exchange interface #211 and DoubleTrouble.jl)
• Parallel remapping (using a super-halo) using TR to generate weights O? Distributed unstructured sparse CPU & GPU matrix-vector multiply, supporting mixed precision #188
• TempestRemap translation to Julia O5.4.1 Conservative regridding package between Ocean and Atmos  #262
• weight generation between conformal and equiangular meshes (extend TempestRemap capability in Julia) O5.1.4 (coupler) Extend TempestRemap functionality to conformal cubed sphere #263
• Spatial memory layout optimization Spatial memory layout optimization (for distributed regridding) #261
• Staggering projection done using Oceananigans’s infrastructure

Inputs

• original TempestRemap code
• ClimaCore interfaces and experiments
• Oceananigans interfaces and experiments
• ClimaComms functionality

Results and Deliverables

• new repo storing interface design https://github.com/CliMA/ClimaCoupler.jl/milestone/10
• simplified HeldSuarez repo for testing https://github.com/CliMA/ClimaCoupler.jl/milestone/9
• new TempestRemap.jl package including extension for conformal cubed spheres https://github.com/CliMA/ClimaCoupler.jl/milestone/8
• Buildkite driver coupling Oceananigans, ClimaLSM and a ClimaCore-based atmos model. https://github.com/CliMA/ClimaCoupler.jl/milestone/10

QA

• should close all issues here

Task Breakdown And Schedule

• Task 1: generalised interface for flux exchange [Greg, Lenka]: Use Oceananigans and ClimaCore to design a Simulations like
  • Port over code from a Held-Suarez experiments + Make new repo - https://github.com/glwagner/ClimaHeldSuarez.jl
  • massage the above into Simulations-like interface
  • set up ClimaEarth with Simulations-like interface
  • add coupling functionality to ClimaEarth
  • enable remapping with staggering
  • add examples to demonstrate Oceananigans and ClimaCore coupling
• Task 2: Parallel remapping: enable parallel remapping in ClimaCore + add drivers in ClimaCoupler O? Distributed unstructured sparse CPU & GPU matrix-vector multiply, supporting mixed precision #188
• Task 3: TempestRemap translate and extension for regridding of spherical domains
  • Backup: Can also try (x)ESMS LLC and equiangular CS? (GISS gnomonic CS and MITgcm LLC example)
• Task 4: Spatial memory layout optimization Spatial memory layout optimization (for distributed regridding) #261
• Task 5: Concurrent coupling
  • Explore/use Julia optimization tools (e.g., async etc)
  • Temporal memory layout optimization (leverage methods of DOE, NCAR, OASIS-MCT (+ research more recent methods)

SDI Revision Log

CC

[LenkaNovak]

To be tackled as part of O5.1 in ClimaEarth