Simon Lee @simonleewx.com · Jan 10 📣 New paper with Lorenzo Polvani published in @agu.org GRL! Increasing Frequency and Persistence of the Summertime Greenland High Regime Not Captured by a Seasonal Prediction Model Very Large Ensemble Open access: doi.org/10.1029/2025... @earthscista.bsky.social @lamont.columbia.edu
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Using a year-round North American weather regime classification (doi.org/10.1175/JCLI...), we find a large increase in the summer frequency and interannual variability of the GH regime in recent decades, which we attribute to increased GH regime persistence through a first-order Markov model.
Given that SEAS5 seems to capture well the extreme frequency/duration of GH blocks, if the GH persistence trend happens to be caused by internal variability (or eventually stops), should one still worry about a systematic bias in the seasonal and/or climate models?