Modellering av reflektans från ett sockerbetsbestånd med hjälp av en strålningsmodell
Canopy characteristicsChlorophyllMappingPhysical geographyLeaf area indexModellingRemote sensingGeomorphologyKlimatologiMarkläraNaturgeografiGeomorfologiPedologyClimatologyCartographyKartografiEarth and Environmental Sciences
The Multispectral Canopy Reflectance Model (MCRM) by Kuusk (1995) has beenused to simulate the reflectance of a sugarbeet canopy. The simulated reflectancevalues show high absorptance in the VIS area, compared to field measurements, andhigh reflectance values in the NIR area. The errors may be due to overestimation ofclorophyll content in the sugarbeet leaves and scattered light during fieldmeasurements. The estimation of the clorophyll content where carried out using thePROSPECT-model by Jacquemoud & Baret (1990).During the vegetation period, the state of the canopy moves towards a closed canopy,with sparse vegetation in spring. The MCRM-model was used to perform a ?spring?simulation, which was compared to the original simulation. It accurately describedthe differences in reflectance between the dense and sparse canopies. Thebackground, i.e. the soil, has larger influence on the canopy reflectance when thecanopy is sparse, while the influence from LAI and clorophyll lessens. The sensitivityof the model changes with the canopy characteristics. In a closed or dense canopy,the leaves completely cover the ground and the sensitivity for leaf properties are high.The sensitivity patterns for a sparse canopy shows a larger sensitivity to soilproperties and lesser sensitivity to leaf properties.