Observational validation of an extended mosaic technique for capturing subgrid scale heterogeneity in a GCM

A technique called extended mosaic (EM) was designed to allow the subgrid scale interactions between the land surface and the atmosphere to extend vertically. EMaddresses a limitation of previously existing techniques, and has been shown to have an important impact on the simulated climate in global models. The present work focuses on an observational validation of the climate characteristics of a general circulation model using EM, based on a set of 10-yr simulations with each of EM and the standard mosaic technique (M), driven by climatological sea surface temperatures. Model simulations using EM show improvements in many aspects of the mid-latitude climate and in wintertime air temperature over Alaska and Western Canada and in the pattern of the Australian monsoon precipitation over land. An example of a degradation in the EM simulation is the temperature over southern South America in wintertime.