A study of non-local effects on the Budyko–Sellers infrared parametrization using atmospheric general circulation models

We perform a series of simplified atmospheric GCM runs with fixed zonally symmetric spherical harmonic sea surface temperature (SST) perturbations to study the response of the outgoing long-wave radiation (OLR) to SST anomalies of different horizontal scales and structures. The classical linear relationship used in energy balance models between the OLR and the SST holds quite well at high latitudes. This is not the case in the tropics; even for large-scale perturbations, especially antisymmetric about the equator, the correlation is poor. This is explained by the fact that the structure of the Hadley cell controls most of the properties of the tropical atmosphere, causing a local relationship between the surface and the top of the atmosphere to break down. This conclusion is supported by our analyses of the relationship between OLR and SST in the wavenumber domain. For very large-scale SST perturbations (wavenumbers 0–2) the agreement is reasonable — the OLR response has most of the energy in the same wavenumber. For higher wavenumbers, however, the correlation deteriorates and the OLR response has significant energy in other harmonics.