 |
| Titel |
Estimation of sunlit/shaded light-use efficiency of cropland using tower-based multi-angle remote sensing data and eddy covariance flux measurements |
| VerfasserIn |
Dongjie Fu, Baozhang Chen, Lifu Zhang |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250103449
|
| Publikation (Nr.) |
 EGU/EGU2015-2861.pdf |
|
|
|
|
|
| Zusammenfassung |
| The light-use efficiency (LUE) is one of critical parameters in the terrestrial ecosystem
production studies. However, it is still a challenge how to up-scale LUE from canopy to the
landscape/regional scales. One potential solution is to use automated multi-angle tower-based
remote sensing platforms, which observe canopy reflectance with high spatial, temporal,
spectral and angle resolution. Although some published paper on the LUE in boreal and
temperate forests had used continuous multi-angle measurements of the surface reflectance,
lack of study in literature investigated the vegetation physiological parameters of cropland
using the surface reflectance with high spatio-temporal and high spectral data with multiple
angles. To improve our understanding of physiological status of cropland, the maize within
the footprint of the Daman Superstation flux tower site of Heihe Watershed Allied Telemetry
Experiment Research (HiWATER) was employed in this study. Based on the observed
reflectance and flux data, a Bidirectional Reflectance Distribution Function (BRDF) of
vegetation index (Photochemical Reflectance Index, PRI and Vegetation Index using the
Universal Pattern Decomposition method, VIUPD) at continuous time series was established
by integrating of a semi-empirical kernel-driven BRDF model (RossThick-LiSparse), a
footprint model (the Simple Analytical Footprint model on Eulerian coordinates for scalar
Flux, SAFE-f) and a LUE model. Besides, based on the sky-condition (direct/diffused
radiation) data, the relationships between the vegetation index (PRI and VIUPD) and
sunlit/shaded LUE under corresponding sky conditions were established. Taking
maize field as an example, the measurements were obtained during June to August,
2012. The relationships between PRI and LUE for sunlit and shaded leaves were:
PRIsu=0.06339xlog(LUEsu) + 0.04882, PRIsh= 0.02675xlog(LUEsh) + 0.01619, where,
the subscript su, sh represent sunlit and shaded leaves respectively; p< 0.0001,
R2 (Coefficient of determination) equal 0.6443 and 0.6081 for sunlit and shaded,
respectively. Then the LUE was up-scaled to landscape/regional scales based on these
relationships and sky conditions, and it can be used for the estimation of gross
primary productivity (GPP) of cropland using a LUE-based model with high accuracy. |
|
|
|
|
|
|