Correlation Between Northern Hemisphere Jet Change and Subtropical-Arctic Warming in CMIP6

Abstract:

Greenhouse gases’ continuously increasing emissions have a variety of implications for the future of our climate patterns. This includes potential changes in the northern hemisphere jet strength and location, which are influenced by the warming in the subtropics and the Arctic. Many climate models disagree on the northern jet response to climate change. Some predict a strengthened jet with a poleward shift in response to increased subtropical warming, and others predict a weakened jet with an equatorward shift in response to increased Arctic warming. This results in the “tug-of-war” hypothesis, that whichever part of the atmosphere, the subtropics or the Arctic, “wins” the tug-of-war by warming more will control the future jet response. This research applies the newer CMIP6 simulations to replicate previous analysis that used the correlation of the difference between upper-tropospheric subtropical warming and Arctic warming with zonal wind speed to predict models’ future jet response. CMIP6 follows the same pattern of previous research, further showing that the two variables are strongly correlated and useful as a predictor of future jet response. Current work focuses on repeating this method with the historical CMIP6 output to determine if the relationship is also evident. Reanalysis and microwave sounding unit observations over the satellite era will then be compared to the historical CMIP6 output to establish the validity of different models’ warming and jet response. Understanding how this simulated relationship relates to data over the satellite era will illuminate the models that are more trustworthy, and allow predictions of the future jet response to be refined.