Continuous observation of leaf area index at Fluxnet-Canada sites

Continuous observation of leaf area index (LAI) is needed in order to interpret and model carbon, water and energy fluxes measured at Fluxnet tower sites. Although remote sensing LAI products can be used in regional and global scale modelling with reasonable performance, the site level modelling of ecophysiological processes needs more accurate LAI time series than those provided by global LAI products. Here we present a semi-empirical approach using satellite measured modified soil-adjusted vegetation index (MSAVI) and sparsely sampled LAI time series measurements at 7 Canadian Carbon Program (CCP) flux tower sites to produce continuous observations of site level LAI. The results indicate that accurate and continuous observation of site level LAI time series is possible using a few ground measurements and remotely sensed MSAVI observations. In order for the semi-empirical model to work correctly, the ground LAI measurements should represent all seasons, preferably including extreme values in winter and the peak of growing season.