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Gross Primary Productivity
This page contains archived content and is no longer being updated. At the time of publication, it represented the best available science. However, more recent observations and studies may have rendered some content obsolete.
NASAs new Moderate-resolution Imaging Spectroradiometer (MODIS)
allows scientists to gauge our planet's metabolism on an almost daily
basis. GPP, gross primary production, is the technical term for plant photosynthesis.
This composite image over the continental United States,
acquired during the period March 26April 10, 2000, shows
regions where plants were more or less productivei.e., where they
#147;inhaled carbon dioxide and then used the carbon from
photosynthesis to build new plant structures.
This false-color image provides a map of how much carbon was absorbed
out of the atmosphere and fixed within land vegetation. Areas
colored blue show where plants used as much as 60 grams of carbon per
square meter. Areas colored green and yellow indicate a range of
anywhere from 40 to 20 grams of carbon absorbed per square meter.
Red pixels show an absorption of less than 10 grams of carbon per
square meter and white pixels (often areas covered by snow or masked as urban) show
little or no absorption.
This is one of a number of new measurements that MODIS provides to
help scientists understand how the Earths landscapes are changing
over time. Scientists goal is use of these GPP measurements to refine
computer models to simulate how the land biosphere
influences the natural cycles of water, carbon, and energy throughout
the Earth system. The GPP will be an integral part of global carbon
cycle source and sink analysis, an important aspect of Kyoto Protocol assessments.
This image is the first of its kind from the MODIS instrument, which
launched in December 1999 aboard the Terra spacecraft. MODIS began
acquiring scientific data on February 24, 2000, when it first opened
its aperture door. The MODIS instrument and Terra spacecraft are
both managed by NASA's Goddard Space Flight Center, Greenbelt, MD.
Image courtesy Steven Running, MODIS Land Group Member, University of Montana