Measurements of surface ultraviolet irradiances are presented for the period of June 1997 to December 1998 from Socorro, NM (34 ¿N, 107 ¿W). The observations are used with results of radiative transfer calculations to retrieve total column ozone. Mean differences between Socorro daily ozone measurements and Earth Probe TOMS satellite data are -1.8 DU and 0.6 DU for 1997 and 1998, respectively. Unusually low ozone was observed in late November and December of 1998, with levels near or below the lowest ozone in the 17-year Nimbus-7 and Earth Probe TOMS record for this location. The clear-sky correlation between the UV Index at 60¿ solar zenith angle and total ozone is well described by a power law, with an exponent (Radiation Amplification Factor) of 0.97¿0.16. One exception occurred during a 10-day period in December 1997 and January 1998 in the aftermath of a heavy snow storm, when the UV Index exhibited clear-sky enhancements of up to 30%. Increases in downwelling ultraviolet radiation were related to a higher effective surface albedo with maximum estimated values between 0.7 to 0.9. ¿ 1999 American Geophysical Union