AVHRR to MODIS Transition for Characterizing Land Surface Phenology

HR: 0800h
AN: B51A-0046 [Abstracts]
TI: AVHRR to MODIS Transition for Characterizing Land Surface Phenology
AU: * Bradley, R
EM: reed@usgs.gov
AF: USGS, 2255 Gemini Drive, Flagstaff, AZ 86001, United States
AU: Eidenshink, J
EM: eidenshink@usgs.gov
AF: Earth Resources Observation and Science USGS, 47914 252nd Street, Sioux Falls, SD 57198, United States
AU: Gallo, K
EM: kgallo@usgs.gov
AF: NOAA, 47194 252nd Street, Sioux Falls, SD 57198, United States
AB: Challenges in characterizing land surface phenology from satellite imagery include creating a suitable phenology interpretation for difficult environments (e.g. arid lands, evergreen forests), dealing with non-vegetation signals, and more directly connecting the results to biophysical processes. In addition, transitioning from one generation of satellite sensors (e.g. AVHRR) to the next (e.g. MODIS) is critical for developing long-term satellite-derived records of phenology. However, this transition presents challenges for land surface phenology research as the sensors have differing radiometry, geometry, calibration, time of overpass and processing strategies. This study addresses some issues in transitioning between sensors by utilizing concurrent 16-day vegetation index composite data sets derived from AVHRR and MODIS. Phenological metrics including start of season and end of season time, duration of growing season, and time-integrated vegetation index are derived and evaluated for each sensor. Results show a varying agreement between the derived metrics, ranging from 0.28 to 0.68 r² for different land cover types. Forested and arid ecosystems have the poorest agreement, while agricultural lands have the highest. While research is in progress to identify and account for the sources of these discrepancies, it is clear that transition algorithms will need to be developed and refined to enable longer term satellite application records.
DE: 0480 Remote sensing
DE: 1630 Impacts of global change (1225)
DE: 1632 Land cover change
SC: Biogeosciences [B]
MN: 2007 Fall Meeting