Temporal Variations of Satellite Indices at the Beginning of the Growing Period of Boreal Evergreen Forest as Detected by Terra/MODIS

Abstract

Relationship between the seasonal change of satellite indices and the beginning of the growing period of boreal evergreen forest was investigated. The data of the flux site "NSA-OBS" was used for the analysis. In this study, the time when NEP turned from negative to positive was defined as the beginning of the growing period. Good correspondence was found between the beginning of the growing period and snow index S3 when it turned from positive to negative. S3=0 is the threshold to estimate snow cover or snow free. Previous studies did not discuss the relationship between snowmelt and CO₂ flux in the study area. Therefore, this study shows the relationship between snowmelt and the beginning of the growing period in the study area for the first time.