SRTM's FAQ shows that the argumentation in the article is backwards. Did the radar sample the tops of trees or the ground level? The radar does not "s

SRTM's FAQ shows that the argumentation in the article is backwards. Did the radar sample the tops of trees or the ground level? The radar does not "see" through thick vegetation canopies. It probably penetrated a little way into some canopies, but in general it followed near the top of the canopy. Did the radar signal bounce off treetops, or topography, or some combination of both that will provide separate data sets (geodesists like myself care about topography, whereas scientists more interested in forestry care about the height of the canopy). Unfortunately, the wavelength used, 5.6 centimeters, didn't penetrate vegetation very well. That means, for moderate-heavy vegetation, we mapped near the canopy top. We did penetrate a little, as some studies comparing our technique with laser altimeters showed, but not to the ground. If the vegetation was sparse, or had no leaves, we might get a return from the ground. The Vegetation Canopy Lidar, scheduled to fly as part of the Earth Observing System, will have this capability, which may provide some interesting data-set comparisons. https://www2.jpl.nasa.gov/srtm/faq.html https://www2.jpl.nasa.gov/srtm/faq.html