Winter cold of eastern continental boundaries induced by warm ocean waters

Both northeastern North America and northeastern Asia in winter are colder than other regions at similar latitudes. This has been attributed to stationary weather systems set by orography and to a lack of maritime influences by the prevailing westerly winds. However, the differences in size and orography between North America and Asia suggest that there are additional mechanisms involved. We show that this anomalous winter cold can result in part through westward radiation of nearly stationary Rossby waves, forming a beta-plume, which are generated by heating of the atmosphere over warm ocean waters. We demonstrate this mechanism through simulations with an idealized general circulation model with a localized surface heating, with which we show how the extent of the cold region depends on properties of Rossby waves, such as their group velocity and its dependence on planetary rotation rate.