(1) IGCR-Tsukuba, Frontier Research System for Global Change
(2) Data Analysis and Research Division, Remote Sensing Technology Center of Japan
(3) Institute of Geoscience, University of Tsukuba; IGCR-Tsukuba, Frontier Research System for Global Change
The phenology of the vegetation over north Asia (mainly over Siberia) and its spatial characteristics were investigated by utilizing remotely-sensed Normalized Difference Vegetation Index (NDVI) data. The analysis was carried out base on weekly NDVI averaged through 3 years (1989 - 1991) using the second generation weekly Global Vegetation Index data set (0.144 x 0.144 spatial resolution). In the NDVI seasonal cycle, three kinds of phenological events, green-up week (NDVI exceeds over 0.2), maximum week, and senescence week (NDVI drops down below 0.2) in a year, were defined at each pixel.
Generally, a west-early east-late spatial gradient was found in those three events. In the zonal transect between 45N and 50N , green-up, maximum, and senescence timings around 60E (Kazakh) is about 3, 8, and 14 weeks earlier than those around 110E (Mongolia), respectively. It was suggested that vegetation around Kazakh can flourish during a short time period when the snow thawing water is available from late spring to early summer. While in Mongolia, abundant water is available for the vegetation even in mid summer due to the precipitation.
In the 50N - 60N zonal transect, the green-up and maximum around 40E are about 4 to 5 weeks earlier than around 115E. As to the week of senescence, there was not a clear regionality. This west-east phenological contrast was tried to relate to the weekly cumulative temperature (over 0C). It was revealed that the weeks in which the cumulative temperature exceeds over 30C and 120C has quite similar west-east regionality with green-up and maximum weeks regionality of the NDVI, respectively.
Submittal Information
Name :
Date :
Rikie Suzuki
22-May-01-13:41:11
Organization :
Theme :
Frontier Research System for Global Change
Theme 4
Address :
Presentation :
c/o National Research Institute for Earth Science and Disaster Prevention, Tennodai 3-1, Tsukuba, Ibaraki 305-0006, Japan