Comparison of climate model large ensembles with observations in the
Arctic using simple neural networks
Abstract
Evaluating historical simulations from global climate models (GCMs)
remains an important exercise for better understanding future
projections of climate change and variability in rapidly warming
regions, such as the Arctic. As an alternative approach for comparing
climate models and observations, we set up a machine learning
classification task using a shallow artificial neural network (ANN).
Specifically, we train an ANN on maps of annual mean near-surface
temperature in the Arctic from a multi-model large ensemble archive in
order to classify which GCM produced each temperature map. After
training our ANN on data from the large ensembles, we input annual mean
maps of Arctic temperature from observational reanalysis and sort the
prediction output according to increasing values of the ANN’s confidence
for each GCM class. To attempt to understand how the ANN is classifying
each temperature map with a GCM, we leverage a feature attribution
method from explainable artificial intelligence. By comparing composites
from the attribution method for every GCM classification, we find that
the ANN is learning regional temperature patterns in the Arctic that are
unique to each GCM relative to the multi-model mean ensemble. In
agreement with recent studies, we show that ANNs can be useful tools for
extracting regional climate signals in GCMs and observations.