HR: 0800h
AN: C21C-1129    [Abstracts]
TI: Satellite derived albedoes during spring melt for selected locations in the Arctic
AU: * Busse, J
EM: jbusse@papagayo.unl.edu
AF: University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340 United States
AU: Anderson, M
EM: mra@unl.edu
AF: University of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340 United States
AB: Snow and ice surfaces have a high level of reflectance, therefore, a high albedo, compared to open water and soil which have lower albedo values and absorb more sunlight. As the high albedo snow and ice begins to melt, the albedo values drop. This contributes to a positive feedback mechanism. The dropping albedo values indicate that more radiation is being absorbed by the surface. As more radiation is absorbed by the surface, more melt occurs, which then leads to lower albedoes and more absorption. This positive feedback continues until the fall when new snow covers the surface and the albedo begins to increase, disrupting the cycle. In the Arctic, the amount of sea ice surviving the summer melt season continues to decrease, indicating a change in the surface conditions during this important melt season. However, very little is known about the albedoes during the melt period. This study documents the albedo changes that occur during the melt season and compares these changes to melt onset dates derived from passive microwave data in order to obtain a multi-frequency response to the energy conditions. Time series of albedo data from the AVHRR Polar Pathfinder Twice-Daily 25-km EASE-Grid Composites are obtained to show the transition from winter to summer conditions from 13 different points within the Arctic. Areas experiencing melt are explored and melt onset dates are determined. Snow and ice melt can also be detected using SMMR and SSM/I passive microwave data. Microwave data are useful to pinpoint when melt occurs, because microwaves can also detect changes in surface conditions. The albedo data are compared with melt onset dates obtained from microwave sensors to determine relationships between microwave-derived melt and albedo responses. Data from areas experiencing early melt onset and late melt onset are explored. Studying the time series from the 13 different points in the Arctic show the relationship between surface melt and albedo variations during the spring to summer transition with the goal that a multiple frequency approach will provide a better understanding of the energy conditions.
DE: 0750 Sea ice (4540)
DE: 0758 Remote sensing
SC: Cryosphere [C]
MN: Fall Meeting 2005