Pictured at top, these graduate students are making measurements of plant productivity in the Canadian boreal forest during the 1994 BOREAS campaign. Below, sun photometers like these were deployed throughout Brazil—in the cerrado and rain-forest regions—to measure optical thickness during the 1995 SCAR-B campaign (David Herring, Goddard Space Flight Center). MISR Validation Field Measurements In the middle and bottom photos, these members of the MISR Team are preparing to make field measurements at Lunar Lake, Nevada, early on the morning of June 5, 1996. Here they are working on a portable instrument that can measure light reflected by the surface in many color bands and at multiple view angles. In the course of the day, they carried this instrument around the test site in a backpack, taking hundreds of images of the surface. During this experiment, they also used instruments that measure sunlight and skylight (Barbara Gaitley, Jet Propulsion Laboratory).

In both the pre- and post-launch periods of Terra, EOS instrument team members and interdisciplinary investigators will conduct scientific field campaigns to verify the quality and long-term stability of the EOS sensors' measurements, as well as the validity of the derived geophysical data products. The magnitudes of any uncertainties and errors in Terra data products must be quantified, on both spatial and temporal scales, to ensure that the data are scientifically credible and maximally useful. Understanding the uncertainties and errors is also essential for future improvement of the algorithms and Earth observing systems.

To obtain the necessary correlative observations required for validation, the EOS Program will use a four-pronged approach that incorporates the following:

1. surface-based (in situ) radiance observations and measurements at specific test sites obtained as part of the EOS interdisciplinary, instrument, and validation teams' investigations;

2. field experiments conducted by EOS interdisciplinary, instrument, and validation teams, as well as participation in, and support of, nationally and internationally coordinated field programs;

3. coordination with national and international observation sites and networks such as the Department of Energy (DoE) Atmospheric Radiation Measurement (ARM) Program, the National Science Foundation (NSF) Long-Term Ecological Research (LTER) sites, and the WCRP Baseline Surface Radiation Network (BSRN); and

4. airborne remote sensing measurements using specifically designed EOS instrument simulators, such as such as the MODIS Airborne Simulator (MAS), AirMISR, MOPITT Airborne Test Radiometer (MATR), and MODIS/ASTER Airborne Simulator (MASTER), as well as community airborne instruments, such as the Airborne Visible and Infrared Imaging Spectrometer (AVIRIS).

EOSDIS will serve as the primary data system for archiving of Science Working Group for the AM Platform (SWAMP) validation data. The EOS Project Science Office Validation Home Page ( http://eospso.gsfc.nasa.gov/validation/valpage.html) includes the Terra Instrument Science Team Validation Plans and a wealth of information on the EOS Validation Program.