TY - JOUR
T1 - The necessity and availability of noise-free daily satellite-observed NDVI during rapid phonological changes in terrestrial ecosystems in East Asia
AU - Nagai, Shin
AU - Saitoh, Taku M.
AU - Suzuki, Rikie
AU - Nasahara, Kenlo Nishida
AU - Lee, Woo Kyun
AU - Son, Yowhan
AU - Muraoka, Hiroyuki
N1 - Funding Information:
We thank K. Kurumado, Y. Miyamoto, and Y. Yashiro (River Basin Research Center, Gifu University), H. Mikami (University of Tsukuba), S. Murayama (National Institute of Advanced Industrial Science and Technology), T. Motohka (Japan Aerospace Exploration Agency), K. Kuwata (University of Tokyo), M. Ishihara (National Institute for Environmental Studies), and T. Inoue (Waseda University) for their assistance in the field and H. Kobayashi (Japan Agency for Marine-Earth Science and Technology) for his helpful comments. We also thank all members of the Phenological Eyes Network for their cooperation. We thank the NASA Land Processes Distributed Active Archive Center in the Earth Observing System Data Gateway for providing the MODIS data. We thank the editor and the two anonymous reviewers for their kind and constructive comments. This study was supported by the Global Environment Research Fund (S-1; Integrated Study for Terrestrial Carbon Management of Asia in the 21st Century Based on Scientific Advancement) of the Ministry of Environment of Japan, the Japan Society for the Promotion of Science (JSPS) 21st Century COE Program (Satellite Ecology, Gifu University), the JSPS-NRF-NSFC A3 Foresight Program, a Global Change Observation Mission (GCOM; PI#102) of the Japan Aerospace Exploration Agency, and the Environment Research and Technology Development Fund (S-9) of the Ministry of the Environment of Japan. S. Nagai and R. Suzuki are supported by the Research Institute for Humanity and Nature (project number D-04). H. Muraoka is supported by JSPS Funding Program for Next Generation World-Leading Researchers (NEXT Program).
Publisher Copyright:
© 2011 Korean Forest Society.
PY - 2011/8/31
Y1 - 2011/8/31
N2 - General, global, long-term, and comprehensive phenological observations are required to evaluate the variability of photosynthetic activities due to environmental changes in terrestrial ecosystems. The observation of seasonal changes and detection of interannual variation in canopy phenology over regional and global scales require satellite data with high temporal resolution (i.e. a daily time step). However, satellite data often include noise caused by snow cover on vegetation, cloud contamination, and atmospheric aerosols. To accurately detect the timing of leaf-expansion and leaf-fall, which occur rapidly, and their rates, it is necessary to examine the observational frequency of noise-free satellite-observed vegetation index data during each phenological period. In this study, we investigated the spatiotemporal distribution of the number of observational days (NUMdays) in the Terra/MODIS (Moderate Resolution Imaging Spectroradiometer)-observed daily high-quality normalized difference vegetation index (NDVIhigh) data with no effects of snow cover, cloud contamination, or atmospheric noise. These data were examined for each month over 10 years in the various ecosystems of East Asia. To ground-truth the relationship between the Terra/MODISobserved daily NDVIhigh data and canopy surface images, we performed a long-term continuous field study in a cooltemperate deciduous broad-leaved forest in central Japan. During the leaf-expansion and leaf-fall periods, the NUMdays for NDVIhigh data in southern Russia, northeastern China, the Tibetan Plateau, Korea, and maritime Japan was about 3-7 for each month. The NUMdays for NDVIhigh data exceeded 10 for each month in arid regions during the growing season and in the subtropical region including northeastern India, Myanmar, and southwestern China during the dry season. In contrast, the NUMdays for NDVIhigh data was almost 0 for each month in southeastern China throughout the year and in the subtropical region during the southeastern monsoon season (July and August). By considering observations from both the Terra/MODIS and Aqua/MODIS satellites, the NUMdays for NDVIhigh data in the deciduous broad-leaved forest in Japan was increased by 40% compared with only Terra/ MODIS satellite observations. Our findings indicate that daily NDVI data from multiple satellites detect the seasonal changes in the various ecosystems of East Asia more accurately than 8-day or biweekly composite NDVI data.
AB - General, global, long-term, and comprehensive phenological observations are required to evaluate the variability of photosynthetic activities due to environmental changes in terrestrial ecosystems. The observation of seasonal changes and detection of interannual variation in canopy phenology over regional and global scales require satellite data with high temporal resolution (i.e. a daily time step). However, satellite data often include noise caused by snow cover on vegetation, cloud contamination, and atmospheric aerosols. To accurately detect the timing of leaf-expansion and leaf-fall, which occur rapidly, and their rates, it is necessary to examine the observational frequency of noise-free satellite-observed vegetation index data during each phenological period. In this study, we investigated the spatiotemporal distribution of the number of observational days (NUMdays) in the Terra/MODIS (Moderate Resolution Imaging Spectroradiometer)-observed daily high-quality normalized difference vegetation index (NDVIhigh) data with no effects of snow cover, cloud contamination, or atmospheric noise. These data were examined for each month over 10 years in the various ecosystems of East Asia. To ground-truth the relationship between the Terra/MODISobserved daily NDVIhigh data and canopy surface images, we performed a long-term continuous field study in a cooltemperate deciduous broad-leaved forest in central Japan. During the leaf-expansion and leaf-fall periods, the NUMdays for NDVIhigh data in southern Russia, northeastern China, the Tibetan Plateau, Korea, and maritime Japan was about 3-7 for each month. The NUMdays for NDVIhigh data exceeded 10 for each month in arid regions during the growing season and in the subtropical region including northeastern India, Myanmar, and southwestern China during the dry season. In contrast, the NUMdays for NDVIhigh data was almost 0 for each month in southeastern China throughout the year and in the subtropical region during the southeastern monsoon season (July and August). By considering observations from both the Terra/MODIS and Aqua/MODIS satellites, the NUMdays for NDVIhigh data in the deciduous broad-leaved forest in Japan was increased by 40% compared with only Terra/ MODIS satellite observations. Our findings indicate that daily NDVI data from multiple satellites detect the seasonal changes in the various ecosystems of East Asia more accurately than 8-day or biweekly composite NDVI data.
KW - East Asia
KW - Ground-truthing
KW - Leaf-expansion
KW - Leaf-fall
KW - MODIS
KW - Phenology
UR - http://www.scopus.com/inward/record.url?scp=84982682918&partnerID=8YFLogxK
U2 - 10.1080/21580103.2011.643388
DO - 10.1080/21580103.2011.643388
M3 - Article
AN - SCOPUS:84982682918
VL - 7
SP - 174
EP - 183
JO - Forest Science and Technology
JF - Forest Science and Technology
SN - 2158-0103
IS - 4
ER -