THE PRODUCTION AND TRANSPORT OF MELTWATER (RUNOFF) IS AN IMPORTANT HYDROLOGICAL PROCESS OPERATING ON PARTS OF THE GREENLAND ICE SHEET SURFACE TODAY AND IS PROJECTED TO BECOME MORE PREVALENT IN THE FUTURE. RUNOFF GENERATED ON THE ICE SHEET SURFACE TYPICALLY PASSES THROUGH MOULINS TO THE BED THUS INFLUENCING BASAL CONDITIONS AND/OR EMANATES FROM THE ICE EDGE TO THE OCEAN THUS CONTRIBUTING TO GLOBAL SEA LEVEL RISE. THE PHYSICAL PROCESS OF SURFACE WATER RUNOFF ON ICE SHEETS THEREFORE WARRANTS STUDY BOTH FOR BASIC SCIENTIFIC UNDERSTANDING AND TO ENABLE BETTER REPRESENTATION AND PARAMETERIZATION OF ICE SHEET SURFACE RUNOFF IN ICE-DYNAMICS AND SURFACE MASS BALANCE (SMB) MODELS. .THE PROPOSED RESEARCH WOULD USE REMOTE SENSING IN SITU MEASUREMENTS ESTABLISHED HYDROLOGICAL THEORY AND MODELS TO ADDRESS THREE CURRENT KNOWLEDGE GAPS ABOUT GRIS SURFACE RUNOFF. THE PRINCIPAL SCIENTIFIC GOALS ARE TO LEARN WHAT AREAS OF THE GREENLAND ICE SHEET RECEIVE INPUTS OF SURFACE RUNOFF TO THE BED; TO IMPROVE REPRESENTATION OF SURFACE RUNOFF IN ICE SHEET MODELS; AND TO ASSESS WHETHER SUPRAGLACIAL DRAINAGE PATTERNS THAT FORM ON THE ICE SHEET SURFACE INFLUENCE ICE DYNAMICS. WE PROPOSE TO ACHIEVE THESE GOALS THROUGH TESTING OF THREE SCIENTIFIC HYPOTHESES AND A FOUR-PART WORK PLAN. IN BRIEF THE WORK PLAN WOULD: .1) USE 2016 SENTINEL-2 VISIBLE/NIR SATELLITE IMAGERY TO CREATE A FIRST PAN-GREENLAND MAP OF SURFACE RUNOFF DRAINAGE PATTERN; .2) OBTAIN IN SITU MEASUREMENTS OF PROGLACIAL RIVER DISCHARGE AT SITES OPTIMAL FOR VALIDATION OF CLIMATE/SMB RUNOFF MODELS INCLUDING A NEW HYDRO-METEOROLOGICAL GAUGING STATION IN INGLEFIELD LAND A UNIQUELY ADVANTAGED LITTLE-STUDIED AREA OF NW GREENLAND; .3) ASSESS AND REFINE CLIMATE/SMB MODEL RUNOFF PRODUCTS AND CALIBRATE A CLASSIC SURFACE WATER ROUTING PARAMETERIZATION FOR USE WITH ICE SHEET MODELS; AND .4) CONDUCT SENSITIVITY TESTS TO DETERMINE THE INFLUENCE OF ROUTING SUPRAGLACIAL RUNOFF TO MAPPED MOULINS IN THE SIMULATIONS OF SUBGLACIAL AND ICE FLOW MODELS. .BY THE CONCLUSION OF THE PROJECT WE ANTICIPATE DELIVERING I) A FIRST PAN-GREENLAND MAP OF SUPRAGLACIAL DRAINAGE PATTERN SURFACE CATCHMENTS AND TERMINAL MOULINS REVEALING WHERE AND HOW MUCH OBSERVABLE SURFACE RUNOFF PENETRATES THE ICE SHEET; II) VALIDATION OF CLIMATE/SMB MODEL RUNOFF PRODUCTS USING IN SITU PROGLACIAL DISCHARGE RECORDS; III) IMPROVED REPRESENTATION OF GRIS SURFACE RUNOFF IN THE MERRA-2 AND ISSM MODELS; IV) A SENSITIVITY STUDY OF THE INFLUENCE (OR LACK THEREOF) OF SURFACE FLUVIAL DRAINAGE PATTERNS ON ICE DYNAMICS. .THE PROPOSAL IS RESPONSIVE TO THIS NASA CRYOSPHERIC SCIENCE SOLICITATION S CALL FOR SYNERGY AMONG OBSERVATIONS MODELING AND FIELD CAMPAIGNS AND TO THREE (OF SEVEN) OF THE SOLICITATION S STATED LONG TERM GOALS NAMELY: DETERMINE THE MECHANISMS CONTROLLING MASS BALANCE AND DYNAMICS OF THE GREENLAND AND ANTARCTIC ICE SHEETS INCLUDING STUDIES AIMED AT IMPROVING FUNDAMENTAL UNDERSTANDING OF THE CONNECTIONS TO THE OCEAN SEA-ICE COVER AND ATMOSPHERE CHARACTERIZE LAND ICE PROPERTIES SUCH AS THICKNESS SURFACE MASS BALANCE ENGLACIAL AND SURFACE WATER LAYERING BED AND GROUNDING LINE PROPERTIES AND ALBEDO AND PHYSICAL PROCESSES SUCH AS FLOW CREVASSING ICE SHELF BEHAVIOR MELT WATER FATE AND CALVING SUCH THAT THEY CAN BE INCORPORATED INTO MODELS USE REMOTE SENSING DATA TO VALIDATE AND IMPROVE MODELS OF LAND-BASED ICE AND THEIR CONTRIBUTIONS TO SEA-LEVEL CHANGE .THE INVESTIGATIVE TEAM CONSISTS OF UNIVERSITY ACADEMICS AND CIVIL SERVANTS WITH PREVIOUS EXPERIENCE IN GREENLAND REMOTE SENSING FIELD WORK AND/OR MODELING. FOUR SUMMER FIELD ASSISTANTSHIPS WOULD INTRODUCE GRADUATE STUDENTS TO GREENLAND. NEW COLLABORATIONS WOULD BE ESTABLISHED WITH THE GEOLOGICAL SURVEY OF DENMARK (GEUS) AND THE GREENLAND WATER SURVEY (ASIAQ) INCLUDING SUPPLYING AUTOMATED WEATHER STATION DATA TO THE DANISH PROGRAMME FOR MONITORING OF THE GREENLAND ICE SHEET (PROMICE) TO FILL A GAP IN NW GREENLAND AWS COVERAGE. .