Publications

Li, XS; Zhang, J (2016). Derivation of the Green Vegetation Fraction of the Whole China from 2000 to 2010 from MODIS Data. EARTH INTERACTIONS, 20.

Abstract
The green vegetation fraction Fg, which represents the horizontal density of live vegetation, is an important parameter for the study of global energy, carbon, hydrological, and biogeochemical cycling. A common method of calculating Fg is to create a simple linear mixing model between two NDVI endmembers: bare soil NDVI, NDVI0, and full vegetation NDVI, NDVI infinity. However, many uncertainties exist for the determination of these parameters at large scales. The present study investigates how NDVI infinity and NDVI0 determination can impact Fg calculations for all of China, based on different land-cover datasets, hyperspectral data, and soil type classification maps. The results show the following: 1) The regional ChinaCover dataset, with higher accuracy and more detailed classification, is preferable for calculating Fg in China, compared with the most commonly used MOD12Q1 dataset, although it would not lead to too much difference in NDVI infinity values. 2) The soil NDVI from Hyperion datasets shows that soils have highly variable NDVI values (0.006-0.2), and 79.36% of the area studied has a much larger NDVI value than the commonly used value of 0.05. Therefore, the dynamic NDVI0 values with different soil types are much better for Fg calculation than the invariant NDVI0 value (0.05), which would yield a significant overestimation of Fg, especially for areas with low vegetation coverage. 3) A high-quality Fg dataset for China from 2000 to 2010 was established with NDVI infinity and NDVI0 parameters based on MOD13Q1 250-m NDVI data.

DOI:
10.1175/EI-D-15-0010.1

ISSN:
1087-3562