Leaf optical properties (reflectance & transmittance) measured by Univsity of Nebraska

Surface reflectance factors, radiances, and temperatures were measured with a Mast-borne Modular Multiband Radiometer (MMR), predominantly in the solar principal plane, with nadir and off-nadir, view-zenith angles. The MMR was mounted on a portable mast in order to achieve a spatial sampling at a variety of sites as well as within each site. The portable mast alignment varied from the solar principal plane, to the azimuthal plane aligned perpendicular to the principal plane and aligned with the satellite azimuthal plane. Measurements were periodically collected with the MMR over a barium sulfate reference panel. Measurements were typically coordinated with aircraft and/or satellite overpasses. Solar radiation data at or near the specific site should be used to screen possible times of variable cloud cover.

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.

The Leaf Area Index and PAR Determined from the UNL Light Bar Data were collected in 1987, 1988, and 1989. Incoming, reflected, and transmitted photosynthetically active radiation (PAR) was measured with a LI-COR LI-191SA line quantum sensor. Absorbed and intercepted PAR calculated from these measurements. The objectives of this research were to characterize bi-directional reflectance factor distributions, estimate surface albedo, determine the variability of reflected and emitted fluxes in selected spectral wavebands as a function of topography, vegetative community and management practice, determine the influence of plant water status on surface reflectance factors, and determine sun angle affects on radiation fluxes.

The MOD15A2H Version 6.1 Moderate Resolution Imaging Spectroradiometer (MODIS) combined Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) product is an 8-day composite dataset with 500 meter (m) pixel size. The algorithm chooses the “best” pixel available from all the acquisitions of the Terra sensor from within the 8-day period.LAI is defined as the one-sided green leaf area per unit ground area in broadleaf canopies and as one-half the total needle surface area per unit ground area in coniferous canopies. FPAR is defined as the fraction of incident photosynthetically active radiation, 400-700 nanometers (nm), absorbed by the green elements of a vegetation canopy.Science Datasets (SDSs) in the Level 4 (L4) MOD15A2H product include LAI, FPAR, two quality layers, and standard deviation for LAI and FPAR. Two low resolution browse images, LAI and FPAR, are also available for each MOD15A2H granule.The LAI product has attained stage 2 (https://landweb.modaps.eosdis.nasa.gov/cgi-bin/QA_WWW/newPage.cgi?fileName=maturity) validation and the FPAR product has attained stage 1 (https://landweb.modaps.eosdis.nasa.gov/cgi-bin/QA_WWW/newPage.cgi?fileName=maturity) validation.Improvements/Changes from Previous Versions* The Version 6.1 Level-1B (L1B) products have been improved by undergoing various calibration changes that include: changes to the response-versus-scan angle (RVS) approach that affects reflectance bands for Aqua and Terra MODIS, corrections to adjust for the optical crosstalk in Terra MODIS infrared (IR) bands, and corrections to the Terra MODIS forward look-up table (LUT) update for the period 2012 - 2017.* A polarization correction has been applied to the L1B Reflective Solar Bands (RSB).

The MMR Calibration Data Set contains radiance data collected in the summer of 1987 and in July and August of 1989 via a Modular Multiband Radiometer (MMR) instrument. The MMR instrument monitored a nearly lambertian calibration panel stationed near the center of the FIFE study area. The radiances recorded from this instrument can be used to monitor solar insolation and clouds. In some cases, these data were also used to calculate the reflectance factor for reflective radiances measured over vegetation using other MMR instruments located at other FIFE sites or mounted on a helicopter.

This data set contains soil moisture data derived from the brightness temperatures measured by the Passive Active L-band System (PALS) microwave aircraft instrument. The data were collected as part of the Soil Moisture Active Passive Validation Experiment 2015 (SMAPVEX15).

This data set contains soil moisture data derived from the brightness temperatures measured by the Passive Active L-band System (PALS) microwave aircraft instrument. The data were collected as part of the Soil Moisture Active Passive Validation Experiment 2015 (SMAPVEX15).

The Visible Infrared Imaging Radiometer Suite (VIIRS) Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) Version 2 data product (VJ115A2H) provides information about the vegetative canopy layer at 500 meter resolution. The VIIRS sensor is located aboard the NOAA-20 satellite. LAI is an index that quantifies the one-sided leaf area of a canopy, while FPAR is the fraction of incoming solar energy absorbed through photosynthesis at 400 to 700 nanometers. This product is intentionally designed after the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) LAI/FPAR operational algorithm to promote the continuity of the Earth Observation System (EOS) mission. The VJ115A2H product includes six Science Data Set Layers for the analysis of key factors in LAI/FPAR measurements. These include the LAI and FPAR measurements, quality detail for LAI/FPAR, extra quality detail for FPAR, and the standard deviation for LAI and FPAR. Two low resolution browse images are also available for each VJ115A2H granule: LAI and FPAR.Known Issues* For complete information about known issues please refer to the [MODIS/VIIRS Land Quality Assessment website](https://landweb.modaps.eosdis.nasa.gov/knownissue?sensor=VIIRS).Improvements/Changes from Previous Version* Improved calibration algorithm and coefficients for entire NOAA-20 mission.* Improved geolocation accuracy and applied updates to fix outliers around maneuver periods.* Corrected the aerosol quantity flag (low, average, high) mainly over brighter surfaces in the mid- to high-latitudes such as desert and tropical vegetation areas. This has an impact on the retrieval of other downstream data products such as VNP13 Vegetation Indices and VNP43 Bidirectional Reflectance Distribution Function (BRDF)/Albedo.* Improved cloud mask input product for corrections along coastlines and artifacts from use of coarse resolution climatology data. * Replaced the land/water mask input product with the eight-class land/water mask from the VNP03 geolocation product that better aligns with MODIS.* More details can be found in this [VIIRS Land V2 Changes document](https://landweb.modaps.eosdis.nasa.gov/data/userguide/VIIRS_Land_C2_Changes_09152022.pdf).

The Visible Infrared Imaging Radiometer Suite (VIIRS) Leaf Area Index (LAI) and Fraction of Photosynthetically Active Radiation (FPAR) Version 1 data product provides information about the vegetative canopy layer at 500 meter resolution (VNP15A2H). The VIIRS sensor is located aboard the NOAA/NASA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. LAI is an index that quantifies the one-sided leaf area of a canopy, while FPAR is the fraction of incoming solar energy absorbed through photosynthesis at 400 to 700 nanometers. This product is intentionally designed after the Terra and Aqua Moderate Resolution Imaging Spectroradiometer (MODIS) LAI/FPAR operational algorithm to promote the continuity of the Earth Observation System (EOS) mission. The VNP15A2H product includes six Science Data Set Layers for the analysis of key factors in LAI/FPAR measurements. These include the LAI and FPAR measurements, quality detail for LAI/FPAR, extra quality detail for FPAR, and the standard deviation for LAI and FPAR. Two low resolution browse images are also available for each VNP15A2H granule: LAI and FPAR.