Temporal validation case study: 6 regression models achieve R²≈0.99 via cross-validation but collapse to R²=0.34 on a real 2020-2023 holdout — investigating why, including a leakage ablation and a failed extrapolation fix
python machine-learning random-forest scikit-learn oceanography xgboost lightgbm climate-data mlp socat model-evaluation catboost google-colab time-series-validation pyco2sys
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Updated
Aug 31, 2026 - Jupyter Notebook