Downwelling and Upwelling Radiation During the Forest Ecosystem Dynamics - Multisensor Aircraft Campaign

Forest Ecosystem Dynamics Multisensor Airborne Campaign (FED MAC):
Hemispherical Downwelling Solar Irradiance and Hemispherical
Upwelling Reflected Radiance of Forest Canopy

The Biospheric Sciences Branch (formerly Earth Resources Branch)
within the Laboratory for Terrestrial Physics at NASA's Goddard Space
Flight Center and associated University investigators are involved in
a research program entitled Forest Ecosystem Dynamics (FED) which is
fundamentally concerned with vegetation change of forest ecosystems at
local to regional spatial scales (100 to 10,000 meters) and temporal
scales ranging from monthly to decadal periods (10 to 100 years). The
nature and extent of the impacts of these changes, as well as the
feedbacks to global climate, may be addressed through modeling the
interactions of the vegetation, soil, and energy components of the
boreal ecosystem.

Measurements of hemispherical downwelling solar irradiance and
hemispherical upwelling reflected radiance from the forest canopy were
taken with pyranometers (0.3 to 3.0 micron) mounted on the tower in
the Northern Experimental Forest in Howland, Maine. Both upward and
downward viewing Eppley PSP pyranometers were mounted on a boom
extending 2.4 meters west from the tower's topmost rail, which is
about 25.8 meters above the ground level. The pyranometer
instantaneous output voltages were recorded in digital form at 59
second intervals on an automatic data logger. The pyranometers used
in this study were intercalibrated against a reference instrument by
exposing all instruments upward on a clear, cloudless day. Calibration
coefficients were then computed for the instruments so that radiances
were equal to the reference instrument values. The instrument that was
used as the reference instrument was calibrated at the Eppley
Laboratory in November 1989.

The FED Home Page is at: "https://forest.gsfc.nasa.gov/".