January 2026 (Month: 2026-01) focused on advancing diffusion physics in FESOM2 to improve accuracy in regions with sharp gradients and preserve mesoscale variability. Delivered a draft implementation adding optional harmonic diffusion coefficients to couple biharmonic and harmonic viscosity diffusion, enabling more selective diffusion and better representation of mesoscale features. The change is tracked under commit fae1ae5154dfb03aaad72271f5cfa026575e5930 for traceability. Next steps include continued validation and production-readiness work.

Month 2025-12 — FESOM2 development focused on strengthening CMIP data quality, configurability, and numerical stability. Delivered centralized CMOR diagnostics with enhanced outputs for CMIP6/CMIP7, migrated configuration to namelist.io for maintainability, and advanced grid handling for level-based FESOM2 grids. Implemented numerical stability improvements in cavity dynamics CFLz, and refined forcing/naming conventions to support CMIP workflows with clearer documentation and safety checks.

Month 2025-11 (FESOM/fesom2) achieved stability, accuracy, and reliability gains across configuration, parallelism, and physics tuning. Key outcomes include stabilized testing environments, safer OpenMP execution, and more accurate simulations.

October 2025 focused on robustness, CI reliability, and configuration-driven capabilities for FESOM2. Delivered a new metric_factor_zero option behind a namelist switch, fixed pointer association after allocation changes, improved restart robustness by warning on mismatches, refined CI baselines with updated truth values and an automation script for maintenance, and cleaned up the build system naming for clarity. These changes reduce maintenance overhead, improve CI trust, and enable controlled experimentation with metric behavior.

September 2025 monthly summary for repository FESOM/fesom2. Focused on delivering tangible features, stabilizing CI, and hardening restart robustness to improve reliability, reproducibility, and developer productivity. Key features delivered and major fixes: - Melt Pond parameterization and output controls in ice model: added pond area, depth, and ice thickness variables; introduced a melt pond toggle; updated albedo and freshwater flux calculations; gating of outputs based on simulation switches (oifs/ifs) and use_meltpond state; default meltpond switch set to false to ensure safe experimentation and controlled activation. - Build system and dependency cleanups for CI: refactored build configuration with CMake, re-enabled original GNU debug flags, moved debug options behind buildtype, removed lasan, and optimized settings for CI reliability and reproducibility. - NetCDF include fix for Fortran interface: added missing include netcdf.inc in gen_surface_forcing.F90 to expose NetCDF Fortran constants nf_noerr and nf_nowrite, enabling correct interface usage. - Robust restart/shutdown handling for mismatched timestamps: when restart timestamps don’t align, now call par_ex to exit gracefully across all MPI processes, improving robustness in parallel runs. - Restart/read_subroutine clarity improvements: refactored read_restart to pass mpicomm and mype directly to par_ex, improving argument handling and maintainability without changing behavior. - Disable thetao diagnostic: removed unused thetao diagnostic call to reduce overhead and potential divergence. Overall impact and accomplishments: - Increased reliability and maintainability of the codebase, improved parallel restart robustness, and more predictable CI behavior. The changes lay groundwork for safer, scalable simulations and faster integration cycles for future features. Technologies/skills demonstrated: - Fortran, MPI parallelism, NetCDF integration, CMake-based build configuration, CI optimization, code refactoring for readability, feature toggling and gating logic, and debugging/issue analysis.

August 2025 monthly summary for esm-tools/esm_tools focusing on LPJ-GUESS configuration modernization, YAML-based template adoption, and ignore rules to improve reproducibility and data quality. The work delivered reduces configuration drift, enables dynamic resource allocations, and filters artifacts for cleaner processing and tracking.

July 2025 saw focused delivery across esm_tools/esm_tools and FESOM/fesom2 to boost scalability, reliability, and automation. Key features include enabling OpenMP for FESOM with config loaded from source files, enabling the MPI switch for OIFS 48r1 with corrected O3 input folder paths, and reducing log noise by default (non-verbose) to improve signal-to-noise for operators and automation. Notable refactors include using create_folders for directory creation to improve reproducibility, along with updates to default versions and runscripts to support stable, scalable runs. A set of targeted bug fixes and stability improvements (Levante procs, beta EVP for SO3, CMIP6 and dataset reverts, and a rollback to a stable MCT) reduce operational risk and improve correctness across platforms. Collectively, these changes advance HPC performance, automation, and maintainability, delivering clearer value to stakeholders and end users.

June 2025 monthly summary for esm_tools/esm_tools and FESOM/fesom2. Focused on delivering robust defaults, multi-model coupling capabilities, and configuration hygiene to enable reproducible, scalable experiments across AWI-CM/ESM3 workflows. Emphasized business value by improving stability, setup simplicity, and CI reliability while enabling new research scenarios through wind coupling and advanced EVP/mEVP selection.

Concise monthly summary for May 2025, focusing on delivered features/bug fixes, impact, and technical accomplishments across the esm_tools/esm_tools and FESOM/fesom2 repositories.

April 2025: Delivered cross-repo Oasis-based and FESOM2 improvements focused on stability, compatibility, and data quality. Implemented OASIS v5.0+ load balancing options and run script updates for esm_tools; added cy48 compatibility for OIFSAMIP and standalone configurations; migrated RNFMAP to send mass fluxes with ocean-side enthalpy computation; fixed restart resume/overwrite handling to prevent unintended data overwrites; increased default output frequency for FESOM2 temperature and salinity to monthly, enabling higher-resolution data by default. These changes improve restart reliability, cross-version stability, data integrity, and deployment reliability in HPC environments.

March 2025 performance summary for the esm_tools repository (esm_tools). Focused on enabling repeatable experiments and improving model integration across AWIESM3 and FESOM workflows. Delivered features for vendor integration, contained runs workflow, test infrastructure, and runtime/config improvements; fixed coupling and config issues to improve reliability and maintainability.

February 2025 performance summary for esm_tools/esm_tools and FESOM/fesom2 focusing on reproducibility, HPC environment tuning, and up-to-date model/tool integrations. Delivered multiple environment standardizations, vendor-branch integrations, and model updates that improve portability, stability, and simulation fidelity across Levante, Juwels, Glogin, and 48r1 workflows.

Concise monthly summary for 2025-01 covering esm_tools and FESOM/fesom2 with business-value oriented outcomes.

December 2024 was focused on portability, reproducibility, and HPC readiness across esm_tools/esm_tools and FESOM/fesom2. Key work delivered includes templating improvements, centralized YAML-based module loading, structural refactor for LPJ-GUESS and Loctrans support, AWICM3 v3.x adjustments to outputs, and critical cleanup for reproducibility. The changes enable yearly restarts, easier configuration management, and more reliable builds across HPC environments.

November 2024: Stabilized cross-platform execution and advanced AWICM v3.x support. Delivered initial v3.3/v3.4 configurations with YAML coupling/configs, new component namelists (FESOM, OIFS, ICEPACK), precision tweaks for OpenIFS, and Lucia-enabled OASIS run scripts to enable longer, configurable simulations. Fixed critical MPI/OpenMPI environment and library path issues to ensure consistent builds/runtimes across platforms. Updated Oasis MCT NLOGPRT handling to work across newer MCT versions while preserving legacy behavior for older versions, enabling reliable load-balancing analysis. These efforts improve reliability, scalability, and onboarding for users deploying AWICM-enabled simulations.

Month: 2024-10 — Focused on improving test environment for faster validation in esm_tools/esm_tools. Implemented test environment configuration enhancements by adjusting simulation parameters and adding NAMFPC namelist parameters for testing/minimal IO scenarios to boost validation throughput and reproducibility. The work enables quicker feedback to developers and more consistent test results, with improved resource efficiency.