Net short wave and net long wave radiation

The incoming solar radiation at the top of the atmosphere is computed from the formulas given in Smithsonian Meteorological Tables (List 1958), with an attenuation by clouds as in Reed (1977). The formula adopted here is the same as described in Rosati and Miyakoda (1988):

The parameter , the incident radiation under clear skies, is composed of direct and diffuse components of short wave radiation:

The direct component of short wave radiation is

where the atmospheric transmission coefficient , is the zenith angle of the sun, and is the incident radiation at the top of the atmosphere. The diffuse component of net short wave radiation is

where is the absorption due to water vapor and ozone. The solar noon altitude in degrees (), , and are computed from present day astronomy (see Appendix B).

The ocean surface albedo is taken from Payne (1972). In order to compute monthly means of , results from the formula are averaged for each day of the month, using analyzed monthly means of cloudiness for .

The net long wave radiation is based on an empirical formula which includes the effect of air-sea temperature difference (e.g., Rosati and Miyakoda 1988)

The dimensionless cloud coefficient is allowed to vary with latitude in order to account for different cloud types (Budyko 1974, Oberhuber 1988). This bulk parameterization is based on a formula originally given by Brunt (1932), later modified to include the term proportional to which attempts to include the effects of the temperature difference between the surface layer and the lower layer of air (Budyko 1974). Although several authors have adopted the proportionality term as above (e.g., Simpson and Paulson 1979, Rosati and Miyakoda 1988), others (Bunker 1976, Hsiung 1986, Oberhuber 1988, Isemer et al. 1989) have used instead.