Observations and simulation of the variability of the stratosphere and troposphere in January.

Global analyses from the lower troposphere to the stratopause for 7 Januaries (1979-85) are used to calculate the ensemble means of the geopotential height field and the zonally averaged temperature and zonal wind fields, together with their daily and interannual variability. These statistics are compared with corresponding statistics from a general circulation model experiment. The model generally simulates the ensemble mean fields reasonably well, but the interannual variability of the model is considerably larger than observed in the high latitude winter stratophere. This excessive variability may be related to the perpetual January methodology used in the model simulation. -from Authors