HR: 1340h
AN: B43B-0265    [Abstracts]
TI: Multi-sensor analysis of changing growing season dynamics across northwest North America since 1998
AU: * Nemani, R
EM: rama.nemani@nasa.gov
AF: NASA Ames Research Center, MS242-4, Moffett Field, CA 94035 United States
AU: White, M
EM: mwhite@cc.usu.edu
AF: Utah State University, Dept aquatic,watershed and earth resources, Logan, UT 84322 United States
AU: Schwartz, M
EM: mds@uwm.edu
AF: University of Wisconsin, Dept of Geography, Milwakee, WI 53201 United States
AU: Saatchi, S
EM: saatchi@congo.jpl.nasa.gov
AF: NASA Jet Propulsion Lab., Mail Stop 300-319, Pasadena, CA 91109 United States
AU: Myneni, R
EM: rmyneni@crsa.bu.edu
AF: Boston University, Dept of Geography, Boston, MA 02215 United States
AU: Dettinger, M
EM: mddettin@usgs.gov
AF: USGS/Scripps Inst. Oceanography, Climate Research Division, La Jolla, CA 92093 United States
AU: Cayan, D
EM: dcayan@ucsd.edu
AF: USGS/Scripps Inst. Oceanography, Climate Research Division, La Jolla, CA 92093 United States
AB: Changes in Pacific Climate on interannual (ENSO) and decadal time scales (Pacific Decadal Oscillation, PDO)have a strong impact on a variety of biospheric processes over northwest North America, including changes in vegetation phenology, snow hydrology, summer drought and fire frequency, forest growth and crop yields. Though evidence exists for a shift in PDO in 1998, the impact of such a shift on terrestrial ecosystems is not yet known. We used a variety of satellite (AVHRR, SSM/I, GOES) and surface (NWS, SNOTEL, streamflow) networks to characterize changes in climate and ecosystem conditions between 1991-97 and 1998-04. Satellite data show that cooler sea surface temperatures during 1998-04 period led to lower atmospheric water vapor over the North Pacific, which in turn led to lower dewpoint and night minimum temperatures over northwest North America. Such climatic changes were dramatic over spring, leading to a delay in the satellite-derived onset of growing season. Modeled budbreak/flowering phases, based on observed weather data, also show a delay of 4-7 days during 1998-04 compared to 1991-97. The delay in growing season onset after 1998 was further supported by later occurrence of soil thaw and snowmelt. It is probably too early to determine if any of the observed changes are a part of the purported shift in PDO. However if they persist, climate-sensitive sectors such as viticulture, with large expansions in recent years, could face potential problems. Continuous monitoring facilitated by a variety of satellite and ground-based sensors offers an unprecedented, spatio-temporal view of changes as they happen.
UR: http://ecocast.arc.nasa.gov
DE: 0315 Biosphere/atmosphere interactions (0426, 1610)
SC: Biogeosciences [B]
MN: Fall Meeting 2005