Accumulation and hoar effects on microwave emission in the Greenland ice-sheet dry-snow zones

Abstract

AbstractThe relationships between accumulation and microwave emissivity in the dry-snow regions of the Greenland ice sheet are studied with special focus on hoar formation. With the use of a discrete-ordinate radiative-transfer model, the relative contributions of hoar and accumulation to microwave omission are examined. The results show that the link between microwave emission and accumulation rates in the dry-snow area of the Greenland ice sheet is significant; however, the emissivity is also dependent on the extent of hoar development. As a result, accumulation estimates based on passive microwave observations in the low-accumulation dry-snow areas will require successful parameterization of hoar formation. Furthermore, the increasing Tb, trends that were observed during the 1980s, which have been hypothesized to be related to accumulation changes, may be strongly related to variations in hoar development. Other possible explanations for these observed trends, such as slight surface melt or atmospheric conditions, are also discussed.