Solar radiation measurements taken at Davis, California (38.5¿N, 121.8¿W, 18 m above mean sea level), are analyzed for the effects of known stratospheric aerosol variation. The data are selected for cloud free periods with high global transmissivity and for zenith angles of 60¿¿2¿. These data include the normal incidence direct and the diffuse and the global components in the spectral intervals 295--3000 nm and 630--3000 nm. Global radiation in the near ultraviolet (295--400 nm) is also analyzed. The data set begins in April 1979 and is analyzed through June 1983. Variations of these data from 3-year averages are compared with observed middle northern latitude stratospheric aerosol variations. The results are that the global UV radiation shows short-period reductions of 10--15% associated with increased stratospheric aerosol. A decrease in the maximum received UV in the fourth quarter of each year is also evident at about 4% per year. The direct components show 7--25% decrease at all wavelengths during periods of increased stratospheric aerosol. The decrease is more persistant at the shorter wavelengths (λ≤630 nm) than for the red and near-IR region. Conversely, the longer-wavelength diffuse components are affected the most by the presence of stratospheric aerosol, with increase of 70--140% over their earlier 3-year mean observed in 1982 and 1983. The global radiation shows relatively small changes with the presence of stratospheric particles. Through most of the observational period, variability in global radiation with stratospheric aerosol variability is comparable to the apparent seasonal variation. However, in 1983, the first quarter global radiation is 12% lower than its preruption value, and the global transmissitivity for the first half of 1983 is nearly 4% lower than its average for the first half of the preceding 3-years. The selective attenuation of direct radiation and the long-term reduction in the shorter-wavelength spectral region imply reduced efficiencies in high-temperature solar to thermal energy applications and to photovoltaic electrical power generation.