Aerosol and Clouds
Significance of multidimensional radiative transfer effects measured in surface fluxes at an Antarctic coastline
Article first published online: 8 OCT 2002
Copyright 2002 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 107, Issue D19, pages AAC 10-1–AAC 10-9, 16 October 2002
How to Cite
Significance of multidimensional radiative transfer effects measured in surface fluxes at an Antarctic coastline, J. Geophys. Res., 107(D19), 4387, doi:10.1029/2001JD002030, 2002., , , and ,
- Issue published online: 8 OCT 2002
- Article first published online: 8 OCT 2002
- Manuscript Accepted: 20 MAR 2002
- Manuscript Revised: 19 MAR 2002
- Manuscript Received: 20 DEC 2001
- shortwave radiation;
- three-dimensional radiative transfer
 At a coastal high-latitude site, multiple reflection of photons between the high albedo surface and an overlying cloud can enhance the downwelling shortwave flux out over the adjacent open water to a distance of several kilometers. This coastal albedo effect has been predicted by theoretical radiative transfer studies and has also been measured under ideal conditions. In this study, three multispectral solar ultraviolet radiometers were deployed in the vicinity of Palmer Station, Antarctica (64° 46′S, 64° 04′W) to determine the prevalence of the coastal albedo effect under the region's natural variability in cloud cover. One radiometer was deployed near the base of a glacier, and the other two radiometers were deployed on Janus Island and Outcast Island, islets ∼2.8 km (1.5 nautical miles) and 5.6 km (3 nautical miles) distant from Palmer Station, respectively. The radiometers were operated simultaneously for 16 days during late December 1999 and January 2000. Under all cloudy sky conditions sampled by this experiment the coastal albedo effect is seen in the data 60% of the time, in the form of a decreasing gradient in surface flux from Palmer Station through Janus and Outcast Islands. During the other 40% of the cloudy sky measurements, local cloud inhomogeneity obscured the coastal albedo effect. The effect is more apparent under overcast layers that appear spatially uniform and occurs 86% of the time under the low overcast decks sampled. The presence of stratus fractus of bad weather, under higher overcast layers, obscures the coastal albedo effect such that it occurs only 43% of the time. A wavelength dependence is noted in the data under optically thin cloud cover: the ratio of a flux measured at an islet to that measured at the station increases with wavelength. This wavelength dependence can be explained by plane-parallel radiative transfer theory.