摘要：We present a dual scale trend analysis for characterizing and comparing two
contrasting areas of change in Russia and Kazakhstan that lie less than
800 km apart. We selected a global NASA MODIS (moderate resolution
imaging spectroradiometer) product (MCD43C4 and MCD43A4) at a
0.05° (~5.6 km) and 500 m spatial resolution and a 16-day temporal resolution from 2000
to 2008. We applied a refinement of the seasonal Kendall trend method to the
normalized difference vegetation index (NDVI) image series at both scales. We
only incorporated composites during the vegetative growing season which was
delineated by start of season and end of season estimates based on analysis of
normalized difference infrared index data. Trend patterns on two scales pointed to
drought as the proximal cause of significant declines in NDVI in Kazakhstan. In
contrast, the area of increasing NDVI trend in Russia was linked through the dual
scale analysis with agricultural land cover change. The coarser scale analysis was
relevant to atmospheric boundary layer processes, while the finer scale data revealed
trends that were more relevant to human decision-making and regional economics.
