MOUNTAIN SNOWPACK SERVES AS AN IMPORTANT NATURAL RESERVOIR OF WATER RECHARGING AQUIFERS SUSTAINING STREAMS AND PROVIDING IMPORTANT ECOSYSTEM SERVICES. SNOW PROVIDES IMPORTANT SPRING MOISTURE FOR FORESTS WHILE FORESTS FUNDAMENTALLY ALTER SNOW ACCUMULATION AND ABLATION. UNDER AVERAGE CONDITIONS THESE INTERACTIONS HAVE IMPORTANT CONNECTIONS WITH WESTERN US WATER RESOURCES ECOHYDROLOGY AND FOREST MANAGEMENT. THE WARMING CLIMATE AND SUBSEQUENT REDUCTION IN SEASONAL SNOWPACK HAS RESULTED IN AN INCREASE IN FOREST FIRES ACROSS THE WESTERN US. THE HYDROLOGIC IMPLICATIONS OF THESE CHANGES REMAIN UNCERTAIN. CONSEQUENTLY THE DEMAND FOR ACCURATE ESTIMATES OF SNOW COVER SNOW ALBEDO SNOW MELT AND DURATION WILL INCREASE AS GLOBAL CLIMATE CHANGES SIMULTANEOUSLY ALTER THE EXTENT AND DURATION OF SNOW-WATER RESOURCES AS WELL AS THE EXTENT AND HETEROGENEITY OF FOREST COVER. FOREST FIRES MODIFY THE SNOW ENERGY BALANCE AND THE SPATIO-TEMPORAL PATTERN OF SNOW ACCUMULATION AND ABLATION. CHARRED FORESTS REDUCE SNOW SURFACE ALBEDO THROUGH DEPOSITION OF LIGHT ABSORBING IMPURITIES (LAI) ON THE SNOWPACK SURFACE FROM STANDING BURNED TREES. ALSO THE MORE OPEN BURNED FOREST CANOPY INCREASES THE TRANSMITTANCE OF SOLAR RADIATION TO THE SNOWPACK SURFACE. AS A RESULT FOREST FIRES ACCELERATE SNOWMELT RATES AND ADVANCE THE TIMING OF SNOWPACK DISAPPEARANCE ACROSS BURNED AREAS FOR MANY YEARS FOLLOWING FIRE. LAI IN SNOW PERPETUATE POWERFUL ALBEDO FEEDBACKS IN BURNED FORESTS HOWEVER NO STUDY HAS CHARACTERIZED THE LIGHT ABSORBING IMPURITIES IN SNOW FOLLOWING FOREST FIRE OR QUANTIFIED THE RESULTING EFFECTS TO SNOW SURFACE ALBEDO ACROSS SPACE AND TIME. THE OVERARCHING GOAL OF THIS PROPOSED RESEARCH IS TO DEVELOP A MUCH NEEDED OBSERVATIONAL AND PREDICTIVE CAPACITY OF HYDROLOGICALLY RELEVANT SNOW PROPERTIES IN BURNED FORESTED WATERSHEDS. TO ACHIEVE THIS GOAL WE WILL ADDRESS THE FOLLOWING SPECIFIC OBJECTIVE: 1. CHARACTERIZE THE SPATIO-TEMPORAL DISTRIBUTIONS OF LAI IN SEASONAL SNOWPACK AND THE RESULTING MULTI-SCALE EFFECTS TO SNOW ALBEDO IN BURNED AND UNBURNED FORESTS. 2. IMPROVE THE REPRESENTATION OF SNOW ALBEDO IN BURNED AND UNBURNED FORESTS IN LAND SURFACE MODELS (LSMS) BY INCORPORATING A FOREST FIRE EFFECTS ON SNOW ALBEDO (FFESA) ALGORITHM. 3. DEVELOP AND ASSESS A HYBRID REMOTE SENSING-MODELING METHOD FOR CHARACTERIZING SNOW ALBEDO IN BURNED FORESTED WATERSHEDS. 4. RECOMMEND STRATEGIES FOR MAPPING AND CHARACTERIZING SNOW IN BURNED FORESTED REGIONS FOR CURRENT AND FUTURE NASA MISSION OUR APPROACH COMBINES REMOTE SENSING AND SNOW MODELING WITH FIELD OBSERVATIONS IN THE TRIPLE DIVIDE REGION AN AREA WITH EXTENSIVE BURNED FORESTS IN MOUNTAINOUS HEADWATERS OF THE THREE MAJOR RIVER SYSTEMS IN THE WESTERN US. THE FIELD MEASUREMENT PLAN INCLUDES A CONSISTENT STRATIFIED SET OF SNOW AND FOREST MEASUREMENTS TO FULLY CHARACTERIZE SNOW ALBEDO- BURNED FOREST INTERACTIONS DURING ACCUMULATION AND ABLATION PERIODS. THESE FINDINGS WILL BE USED TO IMPROVE REPRESENTATIONS OF SNOW ALBEDO-BURNED FOREST INTERACTIONS IN LSMS AND TO ASSESS MODEL PERFORMANCE. REMOTE SENSING DATA FROM A RANGE OF INSTRUMENTS WILL PROVIDE MULTI-SCALE MEASUREMENTS OF SNOW COVERED AREA ALBEDO MELT ONSET AND SNOW DISAPPEARANCE. OUR INTEGRATED APPROACH WILL USE REMOTE SENSING TO INFORM THE LSM OF BURNED FOREST STRUCTURE AND SNOW CONDITIONS AND WILL USE THE MODEL TO EVALUATE HYDROLOGICAL IMPACTS OF FOREST FIRE EFFECTS ON OUR APPROACH COMBINES REMOTE SENSING AND SNOW MODELING WITH FIELD OBSERVATIONS IN THE TRIPLE DIVIDE REGION AN AREA WITH EXTENSIVE BURNED FORESTS IN MOUNTAINOUS HEADWATERS OF THE THREE MAJOR RIVER SYSTEMS IN THE WESTERN US. THE FIELD MEASUREMENT PLAN INCLUDES A CONSISTENT STRATIFIED SET OF SNOW AND FOREST MEASUREMENTS TO FULLY CHARACTERIZE SNOW ALBEDO- BURNED FOREST INTERACTIONS DURING ACCUMULATION AND ABLATION PERIODS. THESE FINDINGS WILL BE USED TO IMPROVE REPRESENTATIONS OF SNOW ALBEDO-BURNED FOREST INTERACTIONS IN LSMS AND TO ASSESS MODEL PERFORMANCE. REMOTE SENSING DATA FROM