NIRvH: Decoupling the soil and vegetation contribution in mixed pixel radiance for the fluorescence yield estimation
Abstract
In 1985-7 Piers Sellers suggested that the near-infrared (NIR) radiance of vegetation (NIRVEG) should be a good proxy for absorbed PAR. An approximation of NIRVEG (NIRv=NDVI×NIR) was introduced to separate the NIR that has interacted with vegetation from contaminated NIR that has also interacted with soils and other non-chlorophyll containing materials. We have found that NIRv is strongly correlated with Solar Induced chlorophyll Fluorescence (SIF), and modeling studies indicate that the ratio of SIF/NIRv should be a good indicator of the fluorescence yield. We are using measurements of SIF and hyperspectral radiance in the 650-850 nm range with the airborne FLEX simulator, i.e., HyPlant, to evaluate this possibility in practice. Based on this study, we introduce the hyperspectral NIRVEG approximation (NIRvH), as an alternative and more accurate approximation of NIRVEG - particularly for sparse vegetation NIRvH takes advantage of variations in the red-edge region of canopy spectra to further reduce the effects of soil contamination and to better isolate the NIR reflectance of vegetation. We find a strong linear correlation with a near-zero intercept between NIRvH and SIF. We mapped fluorescence yield using the HyPlant-based NIRvH and SIF, and found that the resulted fluorescence yield map correctly represented the designed spatial patterns of heat and water stress.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B11Q2280Z
- Keywords:
-
- 3322 Land/atmosphere interactions;
- ATMOSPHERIC PROCESSES;
- 0428 Carbon cycling;
- BIOGEOSCIENCES;
- 0480 Remote sensing;
- BIOGEOSCIENCES;
- 1615 Biogeochemical cycles;
- processes;
- and modeling;
- GLOBAL CHANGE