THE PERCOLATION ZONE OF THE GREENLAND ICE SHEET (GRIS) IS CHARACTERIZED BY HETEROGENEOUS SNOW AND FIRN STRUCTURE MITIGATED BY SHORT DURATION MELT EVENTS IN WHICH MELTWATER PERCOLATES THROUGH THE SNOWPACK AND MOSTLY REFREEZES. THE GRIS HAS EXPERIENCED SIGNIFICANT AND WIDE SPREAD WARMING OVER THE LAST COUPLE DECADES RESULTING IN INCREASING OCCURRENCE AND INTENSITY OF SURFACE MELTING OVER THE PERCOLATION ZONE EVEN THOUGH THIS FACIES HAS REMAINED SPATIALLY STABLE BELOW 2000 M DURING THE 20TH CENTURY. MELT ENHANCEMENTS WITHIN THIS FACIES COULD FACILITATE NEAR SUBSURFACE CONDITIONS SUITABLE FOR THE ENCROACHMENT OF MORE DEVELOPED SUPRAGLACIAL HYDROLOGIC SYSTEMS (I.E. LAKES STREAMS). GIVEN THIS WE SEEK TO LEVERAGE NASA OPERATIONAL ICEBRIDGE RADAR TO UPDATE THE SPATIAL EXTENT OF THE PERCOLATION ZONE FROM 2009 TO PRESENT. OVER THIS PERIOD WE WILL EVALUATE SPATIAL VARIABILITY IN CONDITIONS IN THE TRANSITIONAL ZONE BETWEEN THE ABLATION AND PERCOLATION FACIES WHICH INCLUDES EXAMINATION OF ICE SHEET-WIDE CHANGES IN THE OCCURRENCE AND DISTRIBUTION OF SUPRAGLACIAL LAKES AND STREAMS. WE WILL ALSO EMPLOY A NOVEL SATELLITE-BASED RETRIEVAL MODEL BASED ON A DATA FUSION OF PASSIVE MICROWAVE AND COUPLED OPTICAL/THERMAL MEASUREMENTS TO ASSESS THE SPATIO-TEMPORAL VARIABILITY IN MELT MAGNITUDE OR SURFACE LIQUID WATER FRACTION. LASTLY WE SEEK TO ASSESS HOW CHANGES IN THE PERCOLATION FACIES CORRELATE WITH PREVIOUSLY DETECTED FIRN AQUIFERS AND DIAGNOSE HOW CONTEMPORARY SEASONAL VARIABILITY IN SURFACE MASS BALANCE CONDITIONS ALLOW FOR THE DEVELOPMENT AND PROLIFERATION OF AQUIFER SYSTEMS.