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Negative GEDI RH Metrics

Posted: Tue Feb 09, 2021 3:49 pm America/New_York
by LP DAAC - ckrehbiel
Question from GEDI NASA Earthdata Webinar: Why are GEDI RH metrics negative for some footprints?

Re: Negative GEDI RH Metrics

Posted: Wed Feb 10, 2021 2:19 pm America/New_York
by LP DAAC - ckrehbiel
Relative Height is calculated by the following equation: elev_highestreturn - elev_lowestmode. The lower RH metrics (e.g., RH10) will often have negative values, particularly in low canopy cover conditions. This is because a relatively high fraction of the waveform energy is from the ground and below elev_lowestmode. For example, if the ground return contains 30% of the energy, then RH1 through 15 are likely to be below 0 since half of the ground energy from the ground return is below the center of the ground return, which is used to determine the mean ground elevation in the footprint (elev_lowestmode). The RH metrics are intended for vegetated surfaces. Results over bare/water surfaces are still valid but may present some confusing results. See Section 6 of the Level 2 User Guide for more detailed information.