Climate models simulate accurate weather patterns in the Pacific Northwest, study finds

Climate models are powerful tools that scientists use to study how the climate system works today and how it will change in the future under different global warming scenarios. As models are updated with new scientific information, they need to be evaluated to see how well they represent various climate features, including weather patterns, found in specific geographic regions.

A new study led by Graham Taylor, a Ph.D. A student in Portland State’s Earth, Environment, and Society program and Paul Loikith, associate professor of geography at PSU, tested how well climate models represent large-scale weather patterns over the Pacific Northwest. Researchers from Oregon State University and the Jet Propulsion Laboratory also contributed to the study, which was published in the journal climate dynamics.

“These complex computer models simulating the Earth system can be viewed as virtual laboratories for climate science experiments,” says Loikith. “If the models cannot reproduce important features of the observed climate, they will not be very useful for studying future climate.”

Because all computer models have different strengths and weaknesses due to physical differences, scientists often use the results of many different climate models to evaluate projections of future climate change. For this study, researchers used data from the state-of-the-art sixth phase of the Coupled Model Intercomparison Project (CMIP6) to test how well 26 different climate models found the range of large-scale atmospheric circulation patterns (such as wind and pressure) over the Pacific Northwest. These patterns range from those associated with warm and dry weather to cold and stormy and everything in between.

To test the models, the team used a machine learning technique called self-organizing maps to group daily weather patterns simulated by the climate models into a set of 12 categories. They did the same for historically observed weather data. Then they compared the two sets of data to see how well they matched.

The researchers found that the climate models generally simulated the observed wind and pressure patterns very well, and that the temperature and precipitation patterns produced by the models closely matched the correct patterns found in the historical data.

These results are important because they suggest that current climate models represent large-scale weather patterns in the Pacific Northwest fairly well and can be used to better understand future climate change as global warming continues.

“These results increase our confidence in the ability of these models to help us better understand how the climate in the region will change and why these changes are occurring,” says Loikith.