Use of change-point detection for friction–velocity threshold evaluation in eddy-covariance studies Public Deposited

http://ir.library.oregonstate.edu/concern/defaults/w3763738j

To the best of our knowledge, one or more authors of this paper were federal employees when contributing to this work. This is the publisher’s final pdf. The published article is copyrighted by Elsevier and can be found at:  http://www.elsevier.com/.

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • The eddy-covariance method often underestimates fluxes under stable, low-wind conditions at night when turbulence is not well developed. The most common approach to resolve the problem of nighttime flux underestimation is to identify and remove the deficit periods using friction-velocity (u*) threshold filters (u*[superscript Th]). This study modifies an accepted method for u*[superscript Th] evaluation by incorporating change-point-detection techniques. The original and modified methods are evaluated at 38 sites as part of the North American Carbon Program (NACP) site-level synthesis. At most sites, the modified method produced u*[superscript Th] estimates that were higher and less variable than the original method. It also provided an objective method to identify sites that lacked a u*[superscript Th] response. The modified u*[superscript Th] estimates were robust and comparable among years. Inter-annual u*[superscript Th] differences were small, so that a single u*[superscript Th] value was warranted at most sites. No variation in the u*[superscript Th] was observed by time of day (dusk versus mid or late night), however, a few sites showed significant u*[superscript Th] variation with time of year. Among-site variation in the u*[superscript Th] was strongly related to canopy height and the mean annual nighttime u*. The modified u*[superscript Th] estimates excluded a high fraction of nighttime data - 61% on average. However, the negative impact of the high exclusion rate on annual net ecosystem production (NEP) was small compared to the larger impact of underestimating the u*[superscript Th]. Compared to the original method, the higher u*[superscript Th] estimates from the modified method caused a mean 8% reduction in annual NEP across all site-years, and a mean 7% increase in total ecosystem respiration (R[subscript e]). The modified method also reduced the u*[superscript Th]-related uncertainties in annual NEP and R-e by more than 50%. These results support the use of u*[superscript Th] filters as a pragmatic solution to a complex problem. (C) 2012 A.G. Barr. Published by Elsevier B.V. All rights reserved.
Resource Type
DOI
Date Available
Date Issued
Citation
  • Barr, A., Gu, L., Law, B., Margolis, H., McCaughey, J., Munger, J., . . . Fischer, M. (2013). Use of change-point detection for friction-velocity threshold evaluation in eddy-covariance studies. Agricultural and Forest Meteorology, 171, 31-45. doi: 10.1016/j.agrformet.2012.11.023
Academic Affiliation
Series
Keyword
Rights Statement
Funding Statement (additional comments about funding)
Publisher
Peer Reviewed
Language
Replaces
Additional Information
  • description.provenance : Made available in DSpace on 2013-04-15T17:48:28Z (GMT). No. of bitstreams: 1 LawBeverlyEForestEcosystemsSocietyUseChangePoint.pdf: 1376264 bytes, checksum: 2bdb494fdcbe52cfd42375221bd79cd5 (MD5) Previous issue date: 2013-04-15
  • description.provenance : Approved for entry into archive by Deborah Campbell(deborah.campbell@oregonstate.edu) on 2013-04-15T17:48:28Z (GMT) No. of bitstreams: 1 LawBeverlyEForestEcosystemsSocietyUseChangePoint.pdf: 1376264 bytes, checksum: 2bdb494fdcbe52cfd42375221bd79cd5 (MD5)
  • description.provenance : Submitted by Deborah Campbell (deborah.campbell@oregonstate.edu) on 2013-04-15T17:47:09Z No. of bitstreams: 1 LawBeverlyEForestEcosystemsSocietyUseChangePoint.pdf: 1376264 bytes, checksum: 2bdb494fdcbe52cfd42375221bd79cd5 (MD5)

Relationships

In Administrative Set:
Last modified: 07/08/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items