Bidirectional reflectances measured with SE590

The SE-590 Spectroradiometer Reflectance Factors from GSFC Data Set contains spectral data collected with the Spectron SE-590 Spectral Radiometer at selected FIFE sites located primarily on the Konza Prairie. These measurements were acquired in conjunction with the Surface Reflectances measured by the PARABOLA bi-directional measurements. Ground SE-590 data were acquired in all four 1987 Intensive Field Campaigns and in the 1989 Intensive Field Campaign. The ground SE-590 data were collected at approximately every 10 degree change in solar zenith angle (SZA) to characterize diurnal variations and/or simultaneous observations acquired by helicopter, airplane, or satellite over flights. The data were collected as wavelength intensity values which were converted to spectral radiances with instrument and campaign-specific calibration coefficients.

Spectral reflectance measurements made by Spectron SE590 instruments in the context of validation of geometric-optical BRDF models

The SE-590 Reflectance Factors and Radiances Measured from a Helicopter Data Set were collected using the helicopter-borne SE-590 during Intensive Field Campaign 5 (IFC-5) in 1989. These data were collected at 17 different grid locations within the FIFE study area. Data were collected on 6 days from July 28, 1989 through August 8, 1989, when sky conditions were clear. The helicopter missions were designed to provide a means of spectrally characterizing each FIFE site and provide an intermediate scale of sampling between that of the surface measurements and the higher altitude aircraft and spacecraft multispectral imaging devices. The SE-590 instrumentation was chosen to provide compatibility with surface-based radiometers and TM spacecraft sensors. Off-nadir measurements were made as a means of providing more accurate estimates of hemispherical reflectance and for use with bi-directional reflectance models.

Spectral reflectance measurements made by Spectron SE590 instruments in the context of validation of geometric-optical BRDF models.

SE-590 reflectance factors and radiances measured from a helicopter

The SE-590 Reflectance Factors and Radiances from UNL Data Set contains surface reflectance and viewing angle data that was collected at three sites within the FIFE study area via a SE590 mounted on a portable mast. All measurements were made on eleven days between July 15 and August 11, 1989. Measurements were typically coordinated with aircraft and/or satellite overpasses. On days when measurements were not made the bare soil was covered with a plastic mulch that allowed moisture to penetrate the surface but hindered the regrowth of the vegetation. Solar radiation data at or near the specific site should be used to screen possible times of variable cloud cover. Canopy, illumination, and viewing geometry are critical in determining the amount of reflected radiation received at the sensor. The measurements were predominantly made in the solar principal plane since the greatest variation in observed reflected radiation is expected to occur in that plane due to extremes in sunlit and shaded portions of the canopy (Norman and Walthall 1985). Reflected radiation measurements were converted to radiances and reflectance factor. Reflected radiation from a field reference panel corrected for non-perfect reflectance and sun angle was used as an estimate of the ideal Lambertian standard surface (Walter-Shea and Biehl 1990).

The SE-590 Leaf Level Spectral Observations from GSFC Data Set were acquired in situ with a Spectron SE590 spectroradiometer fitted with the 1 degree IFOV lens, and coupled with a LI-COR integrating sphere. The purpose in collecting SE590 leaf reflectance and transmittance data was to characterize the optical properties of the canopy components to gain a better understanding of how these optical properties contribute to canopy reflection and absorption of radiation. To measure the reflectance and transmittance of leaf surfaces an integrating sphere was used. The integrating sphere collected all of the radiation reflected from or transmitted through a surface. These data are the average spectral optical properties (i.e., reflectance, transmittance) and the standard deviations for the three dominant species found on each of three sites: 916 (i.e., Big Bluestem, Indiangrass, and Switchgrass), 906 (i.e., Big Bluestem, Indiangrass, and Switchgrass), and 26 (i.e., Big Bluestem, Lovegrass and Dropseed) during late July and early August, 1989. The average spectral reflectance and transmittance represent the mean values for the adaxial (top) and abaxial (bottom) sides of 4 - 10 leaves for wavelengths between 400 - 1050 nm at approximately 3 nm intervals.

Leaf optical properties (reflectance & transmittance) from SE590 & LICOR

Bidirectional spectral reflectance factors of landscape elements (litter, scrubs and grasses, leaves) measured by the Spectron SE590 spectroradiometer.