Measurements of Erythemal Irradiance near Davis Station, Antarctica: Effect of Inhomogeneous Surface Albedo

To examine effects of inhomogeneous surface albedo on UV irradiance, measurements were taken near Davis Station (68.58° S, 77.97° E), East Antarctica during November/December 1997. Data were collected in transects perpendicular to an ice/water boundary, while one instrument continuously measured at the ice edge. Irradiances along transects were normalised by coincident measurements at the ice edge. Systematic differences in downwelling irradiance near the ice edge were observed over the highly reflective surface and open water. For cloudless conditions, the relative change in irradiance reached limiting values of about +5% from the ice edge to a point 2.5 km over snow-covered ice, and about -5% from the ice edge to a point 2.5 km over water. In overcast conditions, higher relative changes were observed (about +30% from the ice edge to a point 2.5 km over ice on 17 November 1997) with no sign of a constant relative change being reached. Copyright 1999 by the American Geophysical Union.