The map was first published in 2010 by Michael Lefsky of Colorado State University and updated last year by Marc Simard of NASA’s Jet Propulsion Laboratory. It is based on data from the Geoscience Laser Altimeter System (GLAS) from the ICESAT satellite and the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra and Aqua satellites, and incorporates additional elevation data from the Shuttle Radar Topography Mission (STRM) and climatology information from the Tropical Rainfall Measuring Mission (TRMM) and the Worldclim database. The updated map has a higher resolution than the original, allowing users to see variations in tree height within an ecosystem, like the differences between seasonally flooded várzea forest and terra firme rainforest in the Amazon.