I am interested in examining the coupling between changes in the hydrologic and energy budgets from the CMIP II simulations. It is known that GCM predictions of the change in global-mean precipitation at the time of doubled CO2 differ by nearly a factor of 4 from one model to the next. On a global mean, the changes in the precipitation are determined by changes in surface evaporation. These associated changes in latent heat flux are, in turn, balanced by changes in other components of the surface energy budget; i.e., IR, solar and sensible heat fluxes.
Thus, intermodel differences in the response of precipitation to global warming are intimately linked to differences in the surface heat flux. It is our objective to better understand the cause of intermodel differences in the response of the hydrologic cycle to increasing CO2 by examining how they are related to changes in the surface energy budget. We hope to identify which components of the surface heat fluxes (IR, solar, sensible) balance the changes in evaporative heat flux. This work aims to build upon a recent paper (Soden, 2000: "The Sensitivity of the Tropical Hydrologic Cycle to ENSO", J. Climate, 13, 538-549) which identified significant discrepancies between AMIP I model simulations and satellite observations of the variability of tropical-mean precipitation and surface IR heat flux. In particular, the CMIP model archive provides the perfect opportunity to examine intermodel differences in surface heat fluxes and their connection to changes in the intensity of the hydrological cycle.
This work requires the following variables which are available from CMIP II:
In addition, to better understand how the changes in the hydrologic/energy budgets are linked to changes in the circulation/lapse-rate we also request: