Newman, M. E., M. A. Alexander, C. R. Winkler, J. D. Scott, and J. J. Barsugli, 2000: A linear diagnosis of the coupled extratropical ocean-atmosphere system in the GFDL AGCM. Atmos. Sci. Lett., 1, 1-8.


Diagnosing a coupled system with linear inverse modelling (LIM) can provide insight into the nature and strength of the coupling. This technique is applied to the cold season output of the GFDL GCM, forced by observed tropical Pacific SSTs and including a slab mixed layer ocean model elsewhere. It is found that extratropical SST anomalies act to enhance atmospheric thermal variability and diminish barotropic variability over the east Pacific in these GCM runs, in agreement with other theoretical and modelling studies. Northwest Atlantic barotropic variability is also enhanced. However, all these feedbacks are very weak. LIM results also suggest that North Pacific extratropical SST anomalies in this model would rapidly decay without atmospheric forcing induced by tropical SST anomalies.