NSF HDR: Physics-based Machine Learning
for Sub-Seasonal Climate Forecasting
NSF HDR: Physics-based Machine Learning
for Sub-Seasonal Climate Forecasting
Forecasts of climate variables on sub-seasonal
time scales (2-8 weeks)
Societal Impact
Agricultural productivity, transportation and aviation systems, and water resource management
Advance machine learning models based on physics laws
Characteristics of Climate Data
Observational data obeying physical laws
is limited
Climate models, e.g., NMME, SubX, etc.
Vast amounts “imperfect” outputs
SSF Benchmark Dataset (1980 - recent)
Prediction task - mean temperature in week 3-4
Residualized w.r.t. climatology, 30-year average
on each location and each date
Climate variables - atmosphere, land, and ocean
Investigate ML approaches to SSF forecasting over the contiguous U.S.
ML models are doing better than climatology
Coastal areas are overall easier to predict than inland
Interpretable Data-driven Climate Indices
Transformation of climate variables via clustering
Spatially coherent
Predictive of key climate variables
Improve predictive performance over raw data
ML-Enhanced Physics
Use machine learning and optimization to improve the performance of physics-based models for earth systems
Climate (Dynamical) Models
Dynamics based on PDEs
(partial differential equations)
Billions of variables governed by PDEs
Several hundreds of parameters characterize
the PDEs
Improve Dynamical Models (PDEs)
Develop ML tools to estimate PDE parameters
Approximate Bayesian Inference
Derivative-Free Optimization (DFO)
Monte Carlo Tree Search (MCTS)
Tune real-world climate model with billions of variables
Approximate Bayesian Inference
Gaussian prior based on the “observational” data
Initial Results CESM2
Estimating clubbgamma and dcs
6 ensemble members
Observations
Model parameters can be estimated fairly accurately after 6 months
Contour plot of objective Contour plot of objective
on a single time interval on six time intervals
Derivative-Free Optimization (DFO)
Initial Results
2-variable Lorenz-96 Model
Observations
Integration over a long-time horizon
Chaotic, hard to optimize
Integration over a short horizon
Akin to convex function, easy to optimiz
Monte Carlo Tree Search (MCTS)
Build a hierarchical partition tree
Search in a coarse-to-fine manner
Descend on most promising branches first based on the mismatch
Find global minimum efficiently