Have you ever wondered how many leaves there are in a forest? Today, scientists use NASA satellites to map leaf area index—images processed to show how much of an area is covered by leaves. For example, a leaf area index of 1 means the area is entirely covered by one layer of leaves. These maps show monthly leaf area index from February 2000 to the present, produced using data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard NASA's Terra satellite. The colors in this palette range from tan, showing little or no leaf cover, to light green, indicating the area is entirely covered by one layer of leaves, to dark green showing thick forest canopies, where seven or more layers of leaves cover an area. Black means no data. Knowing the total area covered by leaves helps scientists monitor how much water, carbon, and energy the trees and plants are exchanging with the air above and the ground below.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0