Interannual variability of precipitation in an ensemble of AMIP climate simulations conducted with the CCC GCM2

In this paper log-linear analysis and analysis of variance methods were use d to analyze the interannual variability and potential predictability of pr ecipitation as Simulated in an ensemble of six 10-yr Atmospheric Model Inte rcomparison Project climate simulations conducted with CCC GCM2, the second -generation general circulation model of the Canadian Centre for Climate Mo delling and Analysis. Since observed 1979-88 sea surface temperatures (SSTs ) and sea ice extent were prescribed as lower boundary conditions in ail si x simulations, it is possible to diagnose the extent to which the variabili ty of the seasonal frequency, seasonal mean intensity, and seasonal total o f precipitation is affected by the prescribed boundary conditions. The spec ified SST-sea ice forcing was found to significantly affect both the freque ncy and intensity of precipitation, particularly in the Tropics, but also i n the temperate latitudes. Precipitation frequency appears to be more sensi tive to the external forcing than precipitation intensity, especially over land areas. Potential predictability from internal sources such as land sur face variations is generally small.