Monitoring Multi -Year Snow Cover Dynamics on the Antarctic Peninsula U sing SAR Imagery

Summary:The capability of mapping different radar glacier zones on a regionalscale using multi-temporalSAR-mosaicsderived from ERS-l/2quicklookimagery is demonstrated. The 1992 and 1997 winter mosaics and the 1998sum­mer mosaic facilitate a discrimination of the major radar glacier zones on theAntarctic Peninsula: (1) the dry snow radar zone, (2) the frozen percolation ra­dar zone, (3) the wet snow radar zone and (4) the bare ice radar zone. The bound­aries between these zones have been identified as indicators of climatic varia­bility providing information on different time scales: (1) the dynamic wet snowline approximately coincides with the position of the actual 0 "C isotherm, (2)the transient snowline at the end of the ablation season documents the spatialextension ofthe ablation zone and (3) the dry snow line is a sensitive indicatorfor singular extreme melt events. Furthermore, SAR-data might be used to estab­lish the timing of melt onset over glaciers and thus enables to determine theduration of the annual ablation period. Comparison of the 1997 winter mosaicwith the mosaic from the 1998 ablation season reveals the seasonallarge-scalepatterns of snow cover dynamics along the Antarctic Peninsula. Although thequicklook - mosaics lack aradiometrie and geometrie correction, they providea cost- andtime-efficienttool for monitoring and investigating the large-scalepatterns of snow cover properties, identifying unusual radar signatures features,and discriminating areas of special interest. This is demonstrated with threeregional case studies from Adelaide Island, the inner Marguerite Bay and theSouth Shetland Islands.Zusammenfassung: Die vorliegende Arbeit zeigt die Moglichkeiten der gros­masstabigen Kartierung verschiedener Radar-Gletscherzonen unter Nutzung vonaus ERS-l/2-Quicklookserzeugten, multi-temporalenSAR-Mosaikenauf. DieMosaike der Winter 1992 und 1997 sowie des Sommers 1998 ermoglichen dieAusscheidung der dominierenden Radar-Gletscherzonenim Bereich der Ant­arktischen Halbinsel: