Sub-Seasonal Climate Forecasting via Machine Learning: Challenges, Analysis, and Advances
This work addresses the challenging problem of SSF, which has societal value for agriculture and emergency planning, but is incremental as it applies existing ML methods to this domain with feature improvements.
The paper tackles sub-seasonal climate forecasting (SSF) for predicting temperature and precipitation over 2-week to 2-month scales in the US mainland, showing that machine learning methods, particularly gradient boosting, outperform climatological baselines, with linear regression and deep learning also performing well with careful feature engineering.
Sub-seasonal climate forecasting (SSF) focuses on predicting key climate variables such as temperature and precipitation in the 2-week to 2-month time scales. Skillful SSF would have immense societal value, in areas such as agricultural productivity, water resource management, transportation and aviation systems, and emergency planning for extreme weather events. However, SSF is considered more challenging than either weather prediction or even seasonal prediction. In this paper, we carefully study a variety of machine learning (ML) approaches for SSF over the US mainland. While atmosphere-land-ocean couplings and the limited amount of good quality data makes it hard to apply black-box ML naively, we show that with carefully constructed feature representations, even linear regression models, e.g., Lasso, can be made to perform well. Among a broad suite of 10 ML approaches considered, gradient boosting performs the best, and deep learning (DL) methods show some promise with careful architecture choices. Overall, suitable ML methods are able to outperform the climatological baseline, i.e., predictions based on the 30-year average at a given location and time. Further, based on studying feature importance, ocean (especially indices based on climatic oscillations such as El Nino) and land (soil moisture) covariates are found to be predictive, whereas atmospheric covariates are not considered helpful.