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Relating CO2 fluxes to spectral vegetation indices in tundra landscapes: importance of footprint definition

Published online by Cambridge University Press:  27 October 2009

A.S. Hope ,
J.B. Fleming ,
G. Vourlitis ,
D.A. Stow ,
W.C. Oechel  and
T. Hack
A.S. Hope
Affiliation:
Department of Geography, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4493, USA
J.B. Fleming
Affiliation:
Department of Geography, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4493, USA
G. Vourlitis
Affiliation:
Department of Biology, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4614, USA
D.A. Stow
Affiliation:
Department of Geography, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4493, USA
W.C. Oechel
Affiliation:
Department of Biology, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4614, USA
T. Hack
Affiliation:
Department of Geography, San Diego State University, 5300 Campanile Drive, San Diego, CA 92182-4493, USA
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Abstract

Carbon flux measurements made at an elevated point are associated with an effective upwind area or ‘footprint.’ Since Arctic tundra landscapes can exhibit substantial heterogeneity within the footprint of an eddy correlation tower, it may be necessary to determine the relative point source contributions to the observed flux if landscape properties are to be related to the flux. This study evaluates the potential importance of representing footprint source contributions in relationships that are developed between tower observations of net ecosystem exchange of carbon dioxide (NEE) and a remotely sensed spectral vegetation index. Satellite data collected over the foothills region of the North Slope of Alaska are used to determine spatial patterns of a spectral vegetation index in the calculated footprints of 30 randomly selected tower locations. A previously developed relationship between NEE and the vegetation index is used to calculate NEE at each tower location using two techniques, one that explicitly considers the footprint pattern of relative contributions to tower fluxes and another that ignores these patterns. The results indicate that if carbon fluxes measured at a tower are to be related to remotely sensed spectral vegetation indices, then it is necessary to consider the relative flux contributions from within the tower footprints for sites on the North Slope of Alaska.

Type
Articles
Information
Polar Record , Volume 31 , Issue 177 , April 1995 , pp. 245 - 250
Copyright
Copyright © Cambridge University Press 1995

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