HR: 17:15h
AN: B44A-05    [Abstracts]
TI: Land Surface Phenologies in the North American Great Plains: Detecting Climate Change Amidst Climate Variation
AU: * Henebry, G M
EM: ghenebry@calmit.unl.edu
AF: University of Nebraska-Lincoln, School of Natural Resources 102 E. Nebraska Hall, Lincoln, NE 68588-0517 United States
AU: Goodin, D G
EM: dgoodin@ksu.edu
AF: Kansas State University, Department of Geography 120 Seaton Hall, Manhattan, KS 66506 United States
AB: The continental climate of the North American Great Plains is characterized by high interannual variability in growing season weather. Local averages of temperature and precipitation are not very helpful for predicting expected growing season conditions for vegetation production. We examined the temperature and precipitation records from a network of 'sentinel' weather stations across Kansas, Nebraska, and South Dakota. We assigned these stations into one or more of Wendland and Bryson's airstream regions (ASRs). For each station for each year, we calculated the day of year that the accumulated growing degree-days using a base of 0 oC reaches particular thermal thresholds. We call these Threshold Arrival Dates (TADs). Within each ASR we analyzed the station time series of TADs for two thermal thresholds--at the beginning and at the middle of the growing season for C4 grasses--using 30 year moving averages and Mann-Kendall trend tests. We found that the interannual variation of the onset of the growing season for C4 has increased over the period of record and especially in the last 30 years. At the same time, the central tendencies of the TADs have not changed significantly over the period of record. We also analyzed the TAD series using frequency domain analyses to identify characteristic periodicities. The spectral densities of the TADs point to possible linkages with climate modes. Finally, using the NASA Pathfinder AVHRR Land NDVI dataset, we demonstrate how to interpret the land surface phenologies revealed by synoptic sensors within the broader context of the regions' climatic envelopes.
DE: 3322 Land/atmosphere interactions
DE: 1851 Plant ecology
DE: 1640 Remote sensing
DE: 0400 Biogeosciences
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting