Berlin 2014 – wissenschaftliches Programm

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UP: Fachverband Umweltphysik

UP 6: Kryosphäre und Ozeanographie

UP 6.1: Vortrag

Mittwoch, 19. März 2014, 11:00–11:15, MAG 100

Snow grain size and snow depth retrieval over sea ice: investigating possible synergies — •Christian Melsheimer — Institut für Umweltphysik, Universität Bremen, Otto-Hahn-Allee 1, 28359 Bremen, Germany

A snow layer on sea ice has several significant effects: (1) The snow layer strongly reduces the heat flow between the ocean underneath the ice and the atmosphere above, which affects ice growth and melting; (2) the grain size of the snow layer determines the albedo and thus affects the radiative balance.

Both snow grain size and snow depth can be determined in principle from satellite remote sensing: The snow depth (SD) on level sea ice can be retrieved from microwave radiances near 19 and 37 GHz measured, e.g. by the sensor AMSR-E on the satellite Aqua (2001–2011) or its successor AMSR2 on the satellite GCOM-W1 (since 2012). The snow grain size (SGS) can be retrieved from visible/near infrared reflectances of three channels of MODIS on the satellites Terra and Aqua.

Here we want to study the synergy of these two remote sensing methods that use completely different parts of the electromagnetic spectrum to retrieve related parameters. Fresh snow has the smallest grains which then gradually grow when the snow ages, in particular after partial melting and refreezing. Thus, snowfall events should have an effect on the retrieved SGS (small) and on the SD (increase). Furthernore, the SD retrieval yields too large results in case of large SGS, so here the SGS retrieval might help to identify areas of bad SD retrieval.