Climate change is expected to bring more rain to the midlatitude regions of the Northern Hemisphere, such as parts of Europe, North America, and East Asia. To answer this, we looked at how large-scale air movements in the atmosphere—especially during winter—are related to precipitation. We used a scientific method called the Transformed Eulerian Mean (TEM) framework, which helps us better understand how rising and sinking air patterns influence rainfall.

Using climate model data from the CMIP6 project, we found that more winter precipitation tends to occur in areas where upward air movement, as described by TEM, becomes stronger. This link becomes even clearer in simulations of high future greenhouse gas emissions. By studying many models, we discovered that this stronger upward motion is mainly driven by how poleward eddy heat moves through the atmosphere.

In short, our study shows that how poleward eddy heat is transported plays a key role in shaping where and how much precipitation increases. Understanding and improving how models simulate these heat movements could help make future precipitation predictions more reliable.