Integrating AVHRR and MODIS data to monitor NDVI changes and their relationships with climatic parameters in Northeast China

On the basis of AVHRR GIMMS NDVI and MODIS NDVI, we constructed monthly NDVI sequences covering Northeast China from 1982 to 2009 using a per-pixel unary linear regression model. The expanded NDVI passed the consistency check and were well used for analysis. The monthly NDVI trends were highly correlated with climatic changes. Spatially averaged NDVI in summer exhibited a downward trend with increased temperature and significantly decreased precipitation in the 28 years. NDVI trends were spatially heterogeneous, corresponding with the regional climatic features of different seasons. NDVI for the 95 meteorological stations exhibited significant correlations with monthly mean temperature and monthly precipitation during the study period. The NDVI–temperature correlation was stronger than NDVI–precipitation correlation in most stations and for all vegetation types. Different vegetation types showed various spatial responses to climatic changes.