Cascading decrease of the surface snow SSA at Kohnen Station, DML, Antarctica

Katharina.Klein [ at ]


Grain size of the surface snow is the key parameter for albedo in interior Antarctica, as impurity content is very small. The snow surface at the end of austral winter is characterized by very small grains. The small snow grains consist of broken precipitation particles and partially sublimated or mechanically fractured older ice particles. The albedo is consequently very high. The size of snow grains can be determined quite accurately by measuring its specific surface area (SSA), which is equivalent to the optical grain radius. The SSA as a material property used for albedo estimates typically shows an annual cycle. During the summer it decreases due to grain coarsening caused by snow metamorphism. However the surface layer is affected by a variety of processes including wind driven redistribution, precipitation or surface hoar formation. To discriminate the influence of the different processes on the evolution of the SSA during the summer we measured SSA along a 50m transect on a daily basis at Kohnen Station (75◦00′ S, 00◦00′ E, 2892 m a.s.l) in Dronning Maud Land (DML) indirectly by reflectance at 1310 nm. We found that the SSA was not reducing steadily but showed a cascading decrease. The peaks corresponded to precipitation events and frost formation lasting for several days and inhibiting the general expected decrease during the summer period. Our study indicates that even small amounts of precipitation during the summer period can affect the decrease of SSA, respectively the albedo, in the DML region on the East Antarctic Plateau.

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Conference (Poster)
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EGU General Assembly 2014, 28 Apr 2014 - 02 May 2014, Vienna.
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Klein, K. , Schneebeli, M. , Birnbaum, G. , Reijmer, C. H. and Freitag, J. (2014): Cascading decrease of the surface snow SSA at Kohnen Station, DML, Antarctica , EGU General Assembly 2014, Vienna, 28 April 2014 - 2 May 2014 .

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