Lambert, S.J., J. Sheng, and J. Boyle, 2002: Winter cyclone frequencies in thirteen models participating in the Atmospheric Model Intercomparison Project (AMIP1). Climate Dynamics, 19, 1-16.
Various aspects of the simulated behaviour of cyclones in thirteen models
participating in the AMIP1 exercise are presented. In the simulation of
the winter climatological mean sea level pressure field for the Northern
Hemisphere, the models produce reasonable simulations of the "semi-permanent"
features of the climatology. The greatest departures from the observed
climatology occur near the exit regions of the oceanic storm tracks; i.e.,
over northwestern North America, over and to the west of the British Isles
and in the Mediterranean. The departures in the three geographical areas
are very systematic in that at least eleven of the models exhibit similar
departures from observations. In the Southern Hemisphere the intensity
of the circumpolar trough is generally well simulated but positioned slightly
too far north. Most models exhibit errors south of Africa, New Zealand,
and South America. The simulations of the cyclone events show that the
models are reasonably successful in reproducing the large-scale aspects
of observed cyclone events but deficiencies in the details of the simulations
are apparent. The paucity of simulated events to the south of the Alps
and to the east of the Rockies suggests that the models have difficulty
simulating lee cyclogenesis. Over much of North America, the models have
difficulty simulating the correct level of synoptic activity as demonstrated
by the low numbers of both cyclone events and anticyclone events. The models
have difficulty simulating the distribution of cyclone events as a function
of central pressure. The most common problem is that the models exhibit
an ever increasing deficit of events with decreasing central pressure.
This problem is more apparent in the Southern Hemisphere than in the Northern
Hemisphere and does not appear to be resolution dependent. There is an
apparent ENSO signal in the observed Northern Hemisphere interannual variability
of intense winter cyclone events. With the exception of ECMWF, the models
fail to reproduce this phenomenon. There is some evidence that the models
do indeed respond to the interannual variability in the SSTs, but the response
tends to be negatively correlated with that of the real atmosphere. In
the Southern Hemisphere, there does not appear to be ENSO-induced interannual
variability in the observed numbers of cyclone events. Consequently, it
could be argued that the models have been reasonably successful in the
Southern Hemisphere since they, like the observations, do not exhibit any
ENSO-induced interannual variability.