Parallel climate model (PCM) control and transient simulations

The Department of Energy (DOE) supported Parallel Climate Model (PCM) makes use of the NCAR Community Climate Model (CCM3) and Land Surface Model (LSM ) for the atmospheric and land surface components, respectively, the DOE Lo s Alamos National Laboratory Parallel Ocean Program (POP) for the ocean com ponent, and the Naval Postgraduate School sea-ice model. The PCM executes o n several distributed and shared memory computer systems. The coupling meth od is similar to that used in the NCAR Climate System Model (CSM) in that a flux coupler ties the components together, with interpolations between the different grids of the component models. Flute adjustments are not used in the PCM. The ocean component has 2/3 degrees average horizontal grid spaci ng with 32 vertical levels and a free surface that allows calculation of se a level changes. Near the equator, the grid spacing is approximately 1/2 de grees in latitude to better capture the ocean equatorial dynamics. The Nort h Pole is rotated over northern North America thus producing resolution sma ller than 3/3 degrees in the North Atlantic where the sinking part of the w orld conveyor circulation largely takes place. Because this ocean model com ponent does not have a computational Feint at the North pole, the Arctic Oc ean circulation systems are more realistic and similar to the observed. The elastic viscous plastic sea ice model has a grid spacing of 27 km to repre sent small-scale features such as ice transport through the Canadian Archip elago and the East Greenland current region. Results from a 300 year presen t-day coupled climate control simulation are presented, as well as for a tr ansient 1% per year compound CO2 increase experiment which shows a global w arming of 1.27 degreesC for a 10 year average at the doubling point of CO2 and 2.89 degreesC at the quadrupling point. There is a gradual warming beyo nd the doubling and quadrupling points with CO2 held constant. Globally ave raged sea level rise at the time of CO2 control simulation are 1% per year transient 1% doubling is approximately 7 cm and at the time of quadrupling it is 23 cm. Some of the regional sea level changes are larger and reflect the adjustments in the temperature, salinity, internal ocean dynamics, surf ace heat flux, and wind stress on the ocean. A 0.5% per year CO2 increase e xperiment also was performed showing a global warming of 1.5 degreesC aroun d the time of CO2 doubling and a similar warming pattern to the 1% CO2 per year increase experiment. El Nino and La Nina events in the tropical Pacifi c show approximately the observed frequency distribution and amplitude, whi ch leads to near observed levels of variability on interannual time scales.