GEDI Surface Topography, Height and 3-D Structure Measurements: Algorithm Overview and Waveform Product Assessment

The Global Ecosystem Dynamics Investigation (GEDI) was launched to the ISS on December 5^th 2018. GEDI is a medium-footprint (25m diameter) waveform-recording laser altimeter system. It is used to measure surface topography and 3-d structure at ~50m spacing along 8 data tracks each separated by about 600 m. Science operations began in May 2019 for a 2 year mission. GEDI utilizes a waveform based approach to record surface structure within each laser footprint. This approach relies extensively on techniques developed using data collected in the airborne environment by the LVIS sensor. Here we describe the algorithms used to derive surface elevation, height and structure measurements from the GEDI waveforms and provide an overview of the data products that are available. Initial validation of the GEDI data products at orbit crossover points will be shown along with comparisons to coincident data collected by the LVIS Facility along and across GEDI reference ground tracks in the US, Canada and Costa Rica.