Quantification of LAI interannual anomalies by adjusting climatological patterns

Scaling variations and shifts in the timing of seasonal phenology are central features of global change research. In this study, we propose a novel climatology fitting approach to quantify inter-annual anomalies in LAI seasonality. A consistent archive of daily LAI estimates was first derived from historical AVHRR satellite data for the 1981-2000 period over a globally representative sample of sites. The climatology values were then computed by averaging multi-year LAI profiles, gap filling and smoothing to eliminate possible high temporal frequency residual artifacts. The inter-annual variations in LAI were finally quantified by scaling and shifting the seasonal climatological patterns to the actual observations. In addition to capturing LAI dynamics and quantifying anomalies, this climatology fitting approach allows improving the continuity and consistency of time series by filling gaps and smoothing LAI dynamics.