This paper presents a reexamination of the Earth radiation budget' parameterization of energy balance climate models in light of data collected over the last 12 years. The study consists of three parts: (1) an examination of the infrared terrestrial radiation to space and its relationship to the surface temperature field on time scales from 1 month to 10 years; 2) an examination of the albedo of the Earth with special attention to the seasonal cycle of snow and clouds; (3) solutions for the seasonal cycle using the new parameterizations with special attention to changes in sensitivity. While the infrared parameterization is not dramatically different from that used in the past, the albedo in the new data suggest that a stronger latitude dependence be employed. After retuning the diffusion coefficient the simulation results for the present climate generally show only a slight dependence on the new parameters. Also, the sensitivity parameter for the model is still about the same (1.25øC for a 1% increase of solar constant) for the linear models and for the nonlinear models that include a seasonal snow line albedo feedback (1.34øC). One interesting feature is that a clear-sky planet with a snow line albedo feedback has a significantly higher sensitivity (2.57øC) due to the absence of smoothing normally occurring in the presence of average cloud cover. 1.relating the outgoing infrared flux to the surface temperature to be determined from data (these are part of the subject of this study); Q is the solar constant divided by 4; S(x, t) is the normalized seasonal distribution of heat flux entering the top of the atmosphere; and a[x, T(•, t)] is the coalbedo, which may be dependent on the local temperature as well as position (also a subject of the present study). In solving the equation we require the boundary condition that the horizontal heat flux into the poles vanish.When the temperature dependence of the coalbedo is held fixed, the model is linear and it is convenient to use the discrete Fourier representation since the harmonics are uncoupled. The nonlinearity stemming from the temperature dependence of the albedo is sufficiently mild that even when it is included the harmonic representation is often a useful approximation. Most of the studies have concentrated on applications that exploit the ability of the linear version of the model to reproduce the ensemble average seasonal cycle in the present and altered climates [Hyde et al., 1990; Crowley and North, 1988; Short et al., 1991; Baum and Crowley, 1991]. In addition, some studies have introduced noise forcing to simulate fluctuations at frequencies away from the forced seasonal cycle and its harmonics [North and Cahalan, 1982; Leung and North, 1990; Leung and North, 1991; Kim and North, 1991]. All of these studies have relied on parameterizations derived from satellite data taken from the 1970s [cf. North and Coakley, 1979]. Nonlinearity enters the model as the snowcover (and possibly cloud) movements alter the albedo leading to a feedback which can increase cl...

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