Future Precipitation Changes over Panama Projected with the Atmospheric Global Model Mri-AGCM3.2

Future change in precipitation over Panama was investigated with 20-km and 60-km mesh global atmospheric models. The present-day climate simulations were conducted for 21 years from 1983 through 2003, driving models by observed historical sea surface temperatures (SST). The future climate simulations were conducted for 21 years from 2079 through 2099, driving models by future SST distributions projected by the Atmosphere-Ocean General Circulation Models that participating in the Fifth phase of Coupled Model Intercomparison Project. The uncertainty of future precipitation change was evaluated by ensemble simulations giving four different SST patterns and three different cumulus convection schemes.

In the future, precipitation increases over the central and eastern part of Panama from May to November corresponding to the rainy season. Uncertainty of future precipitation change depends on cumulus convection schemes rather than SST distributions. Increase of precipitation over most regions can be attributed to the increase of water vapor transport originated in the Caribbean Sea which converges over Panama. Precipitation averaged over the Panama canal, the Gatun lake and related river basin (79.0-80.5°W, 8.5-9.5°N) will increase during the rainy season persisting from May to October, while precipitation in dry season persisting from December to April does not change in the future. Intense precipitation increases, but the possibility of drought increases. These results suggest that the planning of water resource management for the Panama canal may require some modifications in the future.