Differences from average atmospheric thickness (standardized geopotential height anomalies) in the column of air over the Arctic from the troposphere to the stratosphere for (left panel) the average over all observed major sudden stratospheric warmings and (right panel) recent observations and forecasts from the Global Forecast System (GFS) model. On average (left panel), increased atmospheric thickness (orange shading) is observed from the middle stratosphere to the tropopause after warming occurs on day 0. Atmospheric thickness is also enhanced below the tropopause but the magnitude is smaller and more intermittent in nature.
In recent observations (right panel), atmospheric thickness was enhanced from the surface to the stratosphere for most of mid-January, but in the last 10 days has been lower than normal (purple shading) in the troposphere. Forecasts suggest the enhanced thickness associated with the major warming in mid-January is descending to the tropopause and may re-emerge in the troposphere in February. NOAA Climate.gov image adapted from original by Amy Butler (left panel) and Laura Ciasto (right panel).