HR: 0800h
AN: B41A-0095    [Abstracts]
TI: Exploring Climate Driven Dynamics in Vegetation Phenology Using Data from MODIS
AU: * Zhang, X
EM: xyzhang@crsa.bu.edu
AF: Xiaoyang Zhang, Dept of Geography/Center for Remote Sensing Boston University 675 Commonwealth Avenue, Boston, MA 02215 United States
AU: Friedl, M A
EM: friedl@crsa.bu.edu
AF: Xiaoyang Zhang, Dept of Geography/Center for Remote Sensing Boston University 675 Commonwealth Avenue, Boston, MA 02215 United States
AU: Schaaf, C B
EM: schaaf@crsa.bu.edu
AF: Xiaoyang Zhang, Dept of Geography/Center for Remote Sensing Boston University 675 Commonwealth Avenue, Boston, MA 02215 United States
AU: Strahler, A H
EM: alan@crsa.bu.edu
AF: Xiaoyang Zhang, Dept of Geography/Center for Remote Sensing Boston University 675 Commonwealth Avenue, Boston, MA 02215 United States
AU: Hodges, J C
EM: jcfh@bu.edu
AF: Xiaoyang Zhang, Dept of Geography/Center for Remote Sensing Boston University 675 Commonwealth Avenue, Boston, MA 02215 United States
AB: Vegetation phenology is an effective indicator of intra-annual dynamics in vegetation growth caused by climate variability. The aim of this study is to use global estimates of vegetation phenological transition dates to (1) examine the controls of climate forcing on global phenological patterns; and (2) to assess the linkage between satellite observations and field measurements. To achieve these goals, we used time series data from NASA�s Moderate Resolution Imaging Spectroradiometer (MODIS). To estimate phenological transition dates from MODIS data, piecewise sigmoidal models were fit to annual trajectories of the enhanced vegetation index computed from MODIS nadir bidirectional reflectance distribution function adjusted reflectances for each pixel at 1 km resolution, globally. Using these models, it is relatively straightforward to identify phenological transition dates over vegetated land areas, including areas with multiple growth cycles. The resultant phenological patterns were then related to MODIS land surface temperature data and precipitation data from the Tropical Rainfall Measuring Mission. The results from this analysis reveal strong relationships between phenology and land surface temperature in the temperate mid-latitudes, and strong covariance between phenology and precipitation in semi-arid regions, especially in regards to the timing of greenup onset. Finally, validation efforts using field measurements show good agreement between satellite-derived transition dates and in-situ measurements. These results provide strong support regarding the quality of global phenological retrievals from MODIS.
DE: 1600 GLOBAL CHANGE (New category)
DE: 1615 Biogeochemical processes (4805)
DE: 1640 Remote sensing
DE: 0315 Biosphere/atmosphere interactions
DE: 0330 Geochemical cycles
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting