Tropical storms are analysed in numerical simulations of two low-resolution Atmospheric General Circulation Model (ECHAM3 and ECHAM4.5) using observed sea surface temperatures for 50 years with a minimum of 10 ensemble members. The tropical storms are detected and tracked and in most ocean basins their climatology are very similar to observed ones.

The influence of different factors in the variability of the frequency, position, track and duration of these model storms is studied. The effect of ENSO on the different basins is analysed and compared with observed studies. Besides ENSO, other factors are also considered, such as sea surface temperature in different regions of the Atlantic and Pacific, and wind shear, which affect the storms at interannual and decadal timescales. Special emphasis is given to the variability of the Western North Pacific basin, including a more detailed analysis for 8 subbasins within the domain.