Solar ultraviolet irradiance in the ozone hole region in Antarctica

To analyze characteristics of solar ultraviolet irradiance in the ozone hole region, solar ultraviolet-B (UV-B : 280-315nm) and ultraviolet-A (UV-A : 315-400nm) irradiance at noon were measured from October 4,1999 to January 31,2000 at Syowa Station in Antarctica (69°00′S, 39°35′E). UV-B irradiance measured at Syowa was compared with UV-B irradiance measured at Tokai University, in Hiratsuka, Kanagawa, Japan (35°21′N, 139°16′E). Maximum irradiance of the UV-B at Syowa was measured early in December 1999. It is equal to the maximum irradiance of UV-B measured in the middle of June 1999 and/or early in September 1999 at Hiratsuka. UV-B and UV-A irradiance at Syowa showed less scatter than that at Hiratsuka. This implies that the difference of scatter between irradiance at Syowa and at Hiratsuka may be attributed to the cloud types which appeared over both observation sites, providing different shielding effects of cloud types for UV irradiance. By eliminating the cloud effect by dividing UV-B irradiance by UV-A irradiance (UV-B/UV-A), a high negative correlation was obtained between UV-B/UV-A and the effective ozone amount. By applying this correlation, total ozone amount can be estimated by use of the values of UV-B/UV-A and air mas