Optimizing Seasonal-to-Decadal Analog Forecasts with a Learned
Spatially-Weighted Mask
Abstract
Seasonal-to-decadal climate prediction is crucial for decision-making in
a number of industries, but forecasts on these timescales have limited
skill. Here, we develop a data-driven method for selecting optimal
analogs for seasonal-to-decadal analog forecasting. Using an
interpretable neural network, we learn a spatially-weighted mask that
quantifies how important each grid point is for determining whether two
climate states will evolve similarly. We show that analogs selected
using this weighted mask provide more skillful forecasts than analogs
that are selected using traditional spatially-uniform methods. This
method is tested on two prediction problems within a perfect model
framework using the Max Planck Institute for Meteorology Grand Ensemble:
multi-year prediction of North Atlantic sea surface temperatures, and
seasonal prediction of El Niño Southern Oscillation. This work
demonstrates a methodical approach to selecting analogs that may be
useful for improving seasonal-to-decadal forecasts and understanding
their sources of skill.