Environmental Science and Engineering Seminar

There is considerable interest in determining how surface temperature variability is influenced by mean warming. Model ensembles project that variability will decrease in the future, consistent with physical arguments related to polar amplification. However, observational studies have thus far come to conflicting conclusions. Several analytical pitfalls in interpreting observational records lead to these discrepancies, and highlight the importance of accounting for non-normality and the effects of filtering, time-averaging, gridding, and smoothing. Applying a set of methods designed to overcome these challenges, I will show that a decrease in temperature variability is already robustly detectable in the extratropics during winter. The effects of polar amplification on synoptic-scale advection explain much of the decreased variability, though a substantial residual signal suggests that additional mechanisms are of similar importance.