Teleconnection Between Large-Scale Oscillations and Northern High-Latitude Terrestrial Net Primary Production
Ke
Zhang, Flathead Lake Biological Station and Numerical Terradynamic Simulation Group, University of Montana, Missoula MT., zhang@ntsg.umt.edu
(Presenting)
John
S
Kimball, Flathead Lake Biological Station and Numerical Terradynamic Simulation Group, University of Montana, Missoula MT., johnk@ntsg.umt.edu
(Presenting)
Kyle
C
McDonald, Jet Propulsion Laboratory, California Institute of Technology, Pasadena CA., kyle.mcdonald@jpl.nasa.gov
John
J
Cassano, CIRES and Department of Atmospheric and Ocean Sciences, University of Colorado, Boulder CO., cassano@cires.colorado.edu
Steve
W
Running, Numerical Terradynamic Simulation Group, University of Montana, Missoula MT., swr@ntsg.umt.edu
We derived annual time series of vegetation net primary production (NPP) and growing season dynamics on a grid cell by cell basis across the pan-arctic basin and Alaska using the MOD17A2/A3 production efficiency model driven by satellite derived leaf area index (LAI) and fraction of photosynthetically active radiation (FPAR) from NOAA AVHRR Pathfinder and NASA EOS MODIS records with gridded daily surface meteorology developed from a regional correction of the NCEP/NCAR reanalysis and NASA SRB daily shortwave solar radiation. Early-spring (Feb-Apr) patterns of the Arctic Oscillation (AO) were found to be proportional to growing season onset (r = -0.653; P = 0.001), while growing season patterns of the Pacific Decadal Oscillation (PDO) were proportional to the supply of plant-available moisture for NPP (r = -0.471; P = 0.02). Relatively strong, negative PDO phases from 1988-1991 and 1998-2002 coincided with prolonged regional droughts indicated by a standardized moisture stress index. These severe droughts resulted in widespread reductions in NPP, especially for relatively drought prone boreal ecosystems. Our results indicate that the AO and PDO influence NPP by regulating the timing of annual growing season onset and the supply of plant-available moisture, respectively. However, the influences of AO and PDO patterns on northern high-latitude vegetation productivity appear to be decreasing and increasing, respectively, as low temperature constraints to plant growth relax and NPP becomes increasingly limited by available water supply under a warming climate.
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