Severe Cold Winters in East Asia Linked to First Winter of La Nina Events and in North America Linked to Second Winter

La Nina often persists for two years, unlike El Nino. Five single-year and 8 multi-year La Nina events occurred over 71 boreal winters (1950/51-2020/21). Atmospheric reanalysis data show a marked increase in diabatic heating over the tropical northwestern Pacific (TNWP) in first winters of La Nina events in addition to a decrease in diabatic heating over the tropical eastern Pacific, common to first and second winters. Linear baroclinic model experiments indicate that combinations of the heating form different atmospheric teleconnections in the mid-latitudes; first winters with the increased heating over the TNWP form teleconnection across the North Pacific, leading to cold winters in Japan. In second winters with the reduced heating over the TNWP (similar to 50% of first winters), teleconnection shifts east, resulting in severe cold winters in northwestern North America, whereas there is no impact on Japan.

Automated summary

La Nina typically lasts for two years, unlike El Nino. In the first winter of La Nina, there is increased diabatic heating over the tropical northwestern Pacific, leading to a teleconnection across the North Pacific and cold winters in Japan. In the second winter, there is reduced diabatic heating over the tropical northwestern Pacific, resulting in a shift of the teleconnection eastward and severe cold winters in northwestern North America, with no impact on Japan.