Sources of variation in radiometric surface temperature over a tallgrass prairie

摘要: Abstract Numerous studies have noted a strong negative correlation between radiometric surface temperature and spectral vegetation indices such as the NDVI, suggested that this relationship might be exploited in strategies to model land energy balance from satellites. These been largely empirical nature relationships among remotely sensed data, properties, produce phenomenon remain unclear. We studied NDVI over tallgrass prairie northeastern Kansas. The study site included mix of landcovers, with fractional cover exposed soil backgrounds much site. observed persistent but found was highly date- time-specific. In context, depend on landcover type, significant proportion total variance both explained by stratifying data class. More importantly, our results show little association for sets acquired aircraft helicopters several dates during growing seasons 1987 1989. Based simulation soil-canopy-sensor system, we hypothesize covariance caused differences background canopy variation cover. This hypothesis is supported evidence showing moisture an important secondary control due its effect thermal inertia, rather than limiting latent heat flux, expected. findings indicate invertible models must account effects landcover, temperatures, before infrared imagery can effectively used estimate fluxes.