SIMULATION OF THE TROPICAL PACIFIC WARM POOL WITH THE NCAR-CLIMATE-SYSTEM-MODEL

The simulation of the tropical western Pacific warm pool is explored w ith the NCAR Climate System Model (CSM). The simulated sea surface tem peratures in the Pacific basin have biases that are similar to other c oupled model simulations in this region. Tn particular, an excessive c old tongue of water extends across the Pacific basin, with warm water on either side of this cold tongue. The warm pool region is also too c old. This cold bias exists in spite of an overestimate in surface net energy flux into this region. To understand the source of this bias in SST. simulations from the uncoupled and fully coupled models are anal yzed in terms of biases in surface energy budget. These analyses sugge st that the strong constraint of little ocean heat transport out of th e warm pool region forces a change in SST gradient that leads to an in crease in the atmospheric zonal wind. This increase in zonal wind caus es an increase in latent heat flux in the warm pool region. The increa se in latent heat flux is required to offset a significant (similar to 35 W m(-2)) bias in net surface solar Aux. The bias in surface solar flux is due to an underestimate of model cloud shortwave absorption.