Title | Spatial scaling of reflectance and surface albedo over a mixed-use, temperate forest landscape during snow-covered periods |
Publication Type | Journal Article |
Year of Publication | 2015 |
Authors | Burakowski, E, Ollinger, SV, Lepine, LC, Schaaf, CB, Wang, Z, Dibb, JE, Hollinger, DY, Kim, JH, Erb, A, Martin, ME |
Journal | Remote Sensing of Environment |
Volume | 158 |
Pagination | 465 - 477 |
Date Published | 2015/03/01/ |
ISBN Number | 0034-4257 |
Keywords | Albedo, Hyperspectral imagery, MODIS, Reflectance, snow, Spatial representativeness, temperate forest |
Abstract | Albedo products from the MODerate resolution Imaging Spectroradiometer (MODIS) have been validated extensively over spatially homogeneous sites with snow-cover. This study evaluated the spatial scaling of albedo and related reflectance-based quantities over areas of high spatial heterogeneity in temperate mixed forest, deciduous forest, urban and built-up, and cropland/natural mosaic lands under snow covered conditions. Reflectance-based quantities evaluated included spectral radiance, surface directional reflectance, and spectral and broadband albedo derived from ground- and tower-based measurements and high-resolution (5 m) hyperspectral imagery (HSI) to coarse resolution (~ 500 m) MODIS satellite data.Our approach first compared ground- and tower-based spectral and broadband reflectance quantities to HSI data, then to evaluate HSI with MODIS reflectance-based products. Over snow-covered pasture, HSI directional reflectance was biased lower than ground-based measurements collected using a spectroradiometer, and greatly underestimated at wavelengths less than 450 nm. Tower-based shortwave broadband albedo (280–2800 nm) and HSI albedo agreed within ± 0.04. HSI directional spectral reflectance agreed well with tower-based measurements of spectral albedo collected using a spectroradiometer and remote cosine receptor above a mixed forest canopy with underlying snow cover. Spectral albedo collected over a dormant deciduous broadleaf canopy increased from 0.10 for snow-free conditions to 0.14–0.18 when snow-cover was present under the canopy. Canopy shortwave broadband albedo was not very sensitive to underlying snowpack depth, indicative of strong vegetation masking. |
URL | http://www.sciencedirect.com/science/article/pii/S0034425714004751 |
Short Title | Remote Sensing of Environment |