HR: 0800h
AN: A41A-0007    [Abstracts]
TI: A Recipe to Include the Vertical Distribution of Radiative Forcing and Feedbacks for Climate Sensitivity Studies
AU: * Lu, J
EM: jlu@met.fsu.edu
AU: Cai, M
EM: cai@met.fsu.edu
AB: This paper proposes a coupled atmosphere-surface climate feedback-response analysis model (CFRAM) as a new framework for estimating climate feedback and sensitivity in coupled general circulation models with a full physical parameterization package. The formulation of the CFRAM is based on the energy balance in an atmosphere-surface column. Because the infrared radiation is the only energy flux term in the balance equation of total energy that is explicitly and directly related to temperatures in the atmosphere-surface column, the CFRAM enable us to determine the coupled atmosphere-surface temperature responses to external climate forcing and subsequent thermodynamic and dynamical feedbacks separately via a linearized infrared radiation transfer model. The decomposition of feedbacks is based on the thermodynamic and dynamical processes that directly affect vertical distribution of individual energy flux terms. Therefore, not only those feedbacks that directly affect the TOA radiative fluxes, such as water vapor, clouds, and ice-albedo feedbacks, but also those feedbacks that do not directly affect the TOA radiation, such as evaporation, convections, and horizontal heat transport, are explicitly included in the CFRAM. In the coupled atmosphere-surface CFRAM, the feedback gain matrices measure the strength of individual feedbacks. The feedback gain matrices can be estimated from the forcing inferred from individual parameterization packages and dynamical modules. The inter-model spread of a feedback gain matrix enables us to quantitatively attribute the differences of climate responses among various climate models to a specific parameterization package or dynamical module and to help us to identify the origins of the uncertainty of future climate projections in climate model simulations. The differences between the CFRAM and other feedback analysis methods, such as the TOA-based partial radiative perturbation (PRP) feedback analysis method and the online feedback suppression approach, will be illustrated using a radiative-convective model.
DE: 3337 Global climate models (1626, 4928)
DE: 3359 Radiative processes
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting