Cross-Product Comparison of Multiple Resolution Microwave Remote Sensing Data Sets Supporting Global Mapping of Inundated Wetlands

Inundated vegetation and open water bodies are common features across the landscape and exert major impacts on hydrologic processes and surface-atmosphere carbon exchange. Their carbon dioxide and methane emissions can have a large impact on global climate. It is therefore of great importance to assess their spatial extent and temporal variations in order to improve upon carbon balance estimates. Despite their importance in the global cycling of carbon and water and climate forecasting, they remain poorly characterized and modeled, primarily because of the scarcity of suitable regional-to-global remote sensing data for characterizing wetlands distribution and dynamics. Spaceborne synthetic aperture radar (SAR) offers an effective tool for characterizing these ecosystems since it is particularly sensitive to surface water and to vegetation structure, and it allows monitoring large inaccessible areas on a temporal basis regardless of atmospheric conditions or solar illumination. We are assembling a multi-year Earth System Data Record (ESDR) of global inundated wetlands to facilitate investigations on their role in climate, biogeochemistry, hydrology, and biodiversity. The ESDR is comprised of (1) fine-resolution (100m) maps of wetland extent, vegetation type, and seasonal inundation extent, derived from L-band SAR data from the Advanced Land Observing Satellite (ALOS) Phased Array L-Band SAR (PALSAR) and the Japanese Earth Resources Satellite (JERS) SAR, for continental-scale areas covering crucial wetland regions, and (2) global multi-temporal mappings of inundation extent at 25 km resolution derived from data sets from combined passive and active microwave remote sensing instruments (AMSR-E, QuikSCAT). We present a comparative analysis of the high-resolution SAR-based data sets and the coarse resolution inundation data sets for wetland ecosystems in the Amazonian tropics and the northern high latitudes of Alaska, Canada, and Eurasia. We compare information content and accuracy of the coarse resolution data sets relative to the SAR-based data sets. We integrate land cover information inferred from the SAR data sets within a calibration-validation scheme to assess potential of improving the accuracy of the coarse resolution data sets. This work has been undertaken in part within the framework of the JAXA ALOS Kyoto & Carbon Initiative. ALOS PALSAR data have been provided by JAXA EORC. Portions of this work were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.