Data analysis and a GCM simulation of the decadal temperature variation in the Arctic lower stratosphere in winter and spring

The lower-stratospheric polar temperatures and the eddy heat fluxes in winter and spring for the past 50 years were investigated based on NCEP/NCAR, ERA40 reanalysis data and a GCM run. Characteristic features of polar temperature in the Arctic lower stratosphere are investigated. The monthly mean polar temperatures at 70 hPa in January, February and March are compared with the eddy heat fluxes at 70 hPa averaged for the preceding two months, respectively. Year-to-year variations of the polar temperature at 70 hPa are correlated with eddy heat flux in both mid-winter and early spring. However, the decadal components of polar temperature and eddy heat flux show different patterns. The polar temperature variation in January is correlated with the stationary eddy heat flux from November 15 to January 15, whereas polar temperature in March is correlated with the transient eddies from January 15 to March 15. The above characteristic features in the decadal temperature variation were tried to be reproduced in a 100-year simulation by the SNUGCM. Although the role of transient and stationary eddies are not dominant in March and January, respectively, they are significant in each month.