Wenyu Zhou, Da Yang, Shang-Ping Xie, and Jing Ma


June 2020

Amplified Madden–Julian oscillation impacts in the Pacific–North America region


The Madden–Julian Oscillation (MJO) is a slow-moving tropical mode that produces a planetary-scale envelope of convective storms. By exciting Rossby waves, the MJO creates teleconnections with far-reaching impacts on extratropical circulation and weather. Although recent studies have investigated the response of the MJO to anthropogenic warming, not much is known about potential changes in its teleconnections. Here, we show that the MJO teleconnection pattern in boreal winter will likely extend further eastward over the North Pacific. This is primarily due to an eastward shift in the exit region of the subtropical jet, to which the teleconnection pattern is anchored, and assisted by an eastward extension of the MJO itself. The eastward-extended teleconnection enables the MJO to have a greater impact downstream on the Northeast Pacific and North American west coast. Over California specifically, the multi-model mean projects a 54% increase in MJO-induced precipitation variability by 2100 under a high-emissions scenario.