QUANTIFYING THE DYNAMIC CHANGES IN SURFACE WATER EXTENT REMAINS A GLOBAL CHALLENGE. CHANGES IN THE SPATIAL EXTENT SEASONAL TIMING AND PERSISTENCE OF SURFACE INUNDATION CAN GREATLY IMPACT CARBON CYCLING IN TERRESTRIAL AND AQUATIC ECOSYSTEMS. SEASONAL FLUCTUATIONS OF WATER OVER ORGANIC-RICH SOILS AND SEDIMENTS ESPECIALLY IN RAPIDLY WARMING ARCTIC-BOREAL ENVIRONMENTS CAN RESULT IN HIGH EMISSIONS OF CH4 A POTENT GREENHOUSE GAS. MANY EFFORTS HAVE BEEN MADE TO DEVELOP GLOBAL-TO-REGIONAL MAPS OF SURFACE INUNDATION. HOWEVER IMPORTANT CHANGES IN LANDSCAPE INUNDATION ARE OCCURRING AT MUCH FINER SPATIAL RESOLUTIONS (&LT;1 TO 3 M) THAT ARE NOT CAPTURED BY EXISTING INUNDATION PRODUCTS. THE PLAN FOR THIS STUDY WILL: 1) FURTHER REFINE AND EVALUATE WATER DETECTION ALGORITHMS THAT CAPITALIZE ON THE FINE (3-M) RESOLUTION AND DAILY TO WEEKLY REVISIT FREQUENCY PROVIDED BY PLANETSCOPE IMAGERY (PLANET LABS) USE THESE ALGORITHMS TO CREATE NEW MULTI-YEAR MAPS (2018-2021) OF WATER COVERAGE FOR TWO TUNDRA AND BOREAL REGIONS IN ALASKA 2) IDENTIFY SEASONAL CHANGES IN FRACTIONAL WATER (FW) COVERAGE ON A PER-PIXEL BASIS IDENTIFY PIXELS HAVING TEMPORAL STABILITY IN WATER COVERAGE AND PIXELS HAVING DYNAMIC SEASONAL WETTING AND DRYING 3) USE THE NEW WATER MAPS TO IMPROVE REGIONAL CH4 EMISSION MAPPING AND IDENTIFY LOCATIONS OF CH4 EMISSION HOTSPOTS USING INFORMATION FROM REMOTE SENSING AND IN SITU OBSERVATIONS.