Gap filling strategies for defensible annual sums of net ecosystem exchange

E. Falge; D. Baldocchi; R. Olson; P. Anthoni; M. Aubinet; C. Bernhofer; G. Burba; R. Ceulemans; R. Clement; H. Dolman; A. Granier; P. Gross; T. Grünwald; D. Hollinger; N.-O. Jensen; G. Katul; P. Keronen; A. Kowalski; C.T. Lai; B.E. Law; T. Meyers; H. Moncrieff; E. Moors; J.W. Munger; K. Pilegaard; Ü. Rannik; C. Rebmann; A. Suyker; J. Tenhunen; K. Tu; S. Verma; T. Vesala; K. Wilson; S. Wofsy

doi:10.1016/S0168-1923(00)00225-2

Gap filling strategies for defensible annual sums of net ecosystem exchange

E. Falge, D. Baldocchi, R. Olson, P. Anthoni, M. Aubinet, C. Bernhofer, G. Burba, R. Ceulemans, R. Clement, H. Dolman, A. Granier, P. Gross, T. Grünwald, D. Hollinger, N.-O. Jensen, G. Katul, P. Keronen, A. Kowalski, C.T. Lai, B.E. LawT. Meyers, H. Moncrieff, E. Moors, J.W. Munger, K. Pilegaard, Ü. Rannik, C. Rebmann, A. Suyker, J. Tenhunen, K. Tu, S. Verma, T. Vesala, K. Wilson, S. Wofsy

Research output: Contribution to journal › Journal article › Research › peer-review

Abstract

Heightened awareness of global change issues within both science and political communities has increased interest in using the global network of eddy covariance flux towers to more fully understand the impacts of natural and anthropogenic phenomena on the global carbon balance. Comparisons of net ecosystem exchange (F-NEE) responses are being made among biome types, phenology patterns, and stress conditions. The comparisons are usually performed on annual sums of F-NEE; however, the average data coverage during a year is only 65%. Therefore, robust and consistent gap filling methods are required.

We review several methods of gap filling and apply them to data sets available from the EUROFLUX and AmeriFlux databases. The methods are based on mean diurnal variation (MDV), look-up tables LookUp, and nonlinear regressions (Regr.), and the impact of different gap filling methods on the annual sum of FNEE is investigated. The difference between annual F-NEE filled by MDV compared to F-NEE filled by Regr. ranged from -45 to +200 g C m(-2) per year (MDV-Regr.). Comparing LookUp and Regr. methods resulted in a difference (LookUp-Regr.) ranging from -30 to +150g Cm-2 per year.

We also investigated the impact of replacing measurements at night, when turbulent mixing is insufficient. The nighttime correction for low friction velocities (u(*)) shifted annual F-NEE on average by +77 g C m(-2) per year, but in certain cases as much as +185 g C m-2 per year.

Our results emphasize the need to standardize gap filling-methods for improving the comparability of flux data products from regional and global flux networks. (C) 2001 Elsevier Science B.V. All rights reserved.

Original language	English
Journal	Agricultural and Forest Meteorology
Volume	107
Issue number	1
Pages (from-to)	43-69
ISSN	0168-1923
DOIs	https://doi.org/10.1016/S0168-1923(00)00225-2
Publication status	Published - 2001

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Falge, E., Baldocchi, D., Olson, R., Anthoni, P., Aubinet, M., Bernhofer, C., Burba, G., Ceulemans, R., Clement, R., Dolman, H., Granier, A., Gross, P., Grünwald, T., Hollinger, D., Jensen, N.-O., Katul, G., Keronen, P., Kowalski, A., Lai, C. T., ... Wofsy, S. (2001). Gap filling strategies for defensible annual sums of net ecosystem exchange. Agricultural and Forest Meteorology, 107(1), 43-69. https://doi.org/10.1016/S0168-1923(00)00225-2

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title = "Gap filling strategies for defensible annual sums of net ecosystem exchange",

abstract = "Heightened awareness of global change issues within both science and political communities has increased interest in using the global network of eddy covariance flux towers to more fully understand the impacts of natural and anthropogenic phenomena on the global carbon balance. Comparisons of net ecosystem exchange (F-NEE) responses are being made among biome types, phenology patterns, and stress conditions. The comparisons are usually performed on annual sums of F-NEE; however, the average data coverage during a year is only 65%. Therefore, robust and consistent gap filling methods are required.We review several methods of gap filling and apply them to data sets available from the EUROFLUX and AmeriFlux databases. The methods are based on mean diurnal variation (MDV), look-up tables LookUp, and nonlinear regressions (Regr.), and the impact of different gap filling methods on the annual sum of FNEE is investigated. The difference between annual F-NEE filled by MDV compared to F-NEE filled by Regr. ranged from -45 to +200 g C m(-2) per year (MDV-Regr.). Comparing LookUp and Regr. methods resulted in a difference (LookUp-Regr.) ranging from -30 to +150g Cm-2 per year.We also investigated the impact of replacing measurements at night, when turbulent mixing is insufficient. The nighttime correction for low friction velocities (u(*)) shifted annual F-NEE on average by +77 g C m(-2) per year, but in certain cases as much as +185 g C m-2 per year.Our results emphasize the need to standardize gap filling-methods for improving the comparability of flux data products from regional and global flux networks. (C) 2001 Elsevier Science B.V. All rights reserved. ",

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author = "E. Falge and D. Baldocchi and R. Olson and P. Anthoni and M. Aubinet and C. Bernhofer and G. Burba and R. Ceulemans and R. Clement and H. Dolman and A. Granier and P. Gross and T. Gr{\"u}nwald and D. Hollinger and N.-O. Jensen and G. Katul and P. Keronen and A. Kowalski and C.T. Lai and B.E. Law and T. Meyers and H. Moncrieff and E. Moors and J.W. Munger and K. Pilegaard and {\"U}. Rannik and C. Rebmann and A. Suyker and J. Tenhunen and K. Tu and S. Verma and T. Vesala and K. Wilson and S. Wofsy",

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doi = "10.1016/S0168-1923(00)00225-2",

language = "English",

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journal = "Agricultural and Forest Meteorology",

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Falge, E, Baldocchi, D, Olson, R, Anthoni, P, Aubinet, M, Bernhofer, C, Burba, G, Ceulemans, R, Clement, R, Dolman, H, Granier, A, Gross, P, Grünwald, T, Hollinger, D, Jensen, N-O, Katul, G, Keronen, P, Kowalski, A, Lai, CT, Law, BE, Meyers, T, Moncrieff, H, Moors, E, Munger, JW, Pilegaard, K, Rannik, Ü, Rebmann, C, Suyker, A, Tenhunen, J, Tu, K, Verma, S, Vesala, T, Wilson, K & Wofsy, S 2001, 'Gap filling strategies for defensible annual sums of net ecosystem exchange', Agricultural and Forest Meteorology, vol. 107, no. 1, pp. 43-69. https://doi.org/10.1016/S0168-1923(00)00225-2

TY - JOUR

T1 - Gap filling strategies for defensible annual sums of net ecosystem exchange

AU - Falge, E.

AU - Baldocchi, D.

AU - Olson, R.

AU - Anthoni, P.

AU - Aubinet, M.

AU - Bernhofer, C.

AU - Burba, G.

AU - Ceulemans, R.

AU - Clement, R.

AU - Dolman, H.

AU - Granier, A.

AU - Gross, P.

AU - Grünwald, T.

AU - Hollinger, D.

AU - Jensen, N.-O.

AU - Katul, G.

AU - Keronen, P.

AU - Kowalski, A.

AU - Lai, C.T.

AU - Law, B.E.

AU - Meyers, T.

AU - Moncrieff, H.

AU - Moors, E.

AU - Munger, J.W.

AU - Pilegaard, K.

AU - Rannik, Ü.

AU - Rebmann, C.

AU - Suyker, A.

AU - Tenhunen, J.

AU - Tu, K.

AU - Verma, S.

AU - Vesala, T.

AU - Wilson, K.

AU - Wofsy, S.

PY - 2001

Y1 - 2001

N2 - Heightened awareness of global change issues within both science and political communities has increased interest in using the global network of eddy covariance flux towers to more fully understand the impacts of natural and anthropogenic phenomena on the global carbon balance. Comparisons of net ecosystem exchange (F-NEE) responses are being made among biome types, phenology patterns, and stress conditions. The comparisons are usually performed on annual sums of F-NEE; however, the average data coverage during a year is only 65%. Therefore, robust and consistent gap filling methods are required.We review several methods of gap filling and apply them to data sets available from the EUROFLUX and AmeriFlux databases. The methods are based on mean diurnal variation (MDV), look-up tables LookUp, and nonlinear regressions (Regr.), and the impact of different gap filling methods on the annual sum of FNEE is investigated. The difference between annual F-NEE filled by MDV compared to F-NEE filled by Regr. ranged from -45 to +200 g C m(-2) per year (MDV-Regr.). Comparing LookUp and Regr. methods resulted in a difference (LookUp-Regr.) ranging from -30 to +150g Cm-2 per year.We also investigated the impact of replacing measurements at night, when turbulent mixing is insufficient. The nighttime correction for low friction velocities (u(*)) shifted annual F-NEE on average by +77 g C m(-2) per year, but in certain cases as much as +185 g C m-2 per year.Our results emphasize the need to standardize gap filling-methods for improving the comparability of flux data products from regional and global flux networks. (C) 2001 Elsevier Science B.V. All rights reserved.

AB - Heightened awareness of global change issues within both science and political communities has increased interest in using the global network of eddy covariance flux towers to more fully understand the impacts of natural and anthropogenic phenomena on the global carbon balance. Comparisons of net ecosystem exchange (F-NEE) responses are being made among biome types, phenology patterns, and stress conditions. The comparisons are usually performed on annual sums of F-NEE; however, the average data coverage during a year is only 65%. Therefore, robust and consistent gap filling methods are required.We review several methods of gap filling and apply them to data sets available from the EUROFLUX and AmeriFlux databases. The methods are based on mean diurnal variation (MDV), look-up tables LookUp, and nonlinear regressions (Regr.), and the impact of different gap filling methods on the annual sum of FNEE is investigated. The difference between annual F-NEE filled by MDV compared to F-NEE filled by Regr. ranged from -45 to +200 g C m(-2) per year (MDV-Regr.). Comparing LookUp and Regr. methods resulted in a difference (LookUp-Regr.) ranging from -30 to +150g Cm-2 per year.We also investigated the impact of replacing measurements at night, when turbulent mixing is insufficient. The nighttime correction for low friction velocities (u(*)) shifted annual F-NEE on average by +77 g C m(-2) per year, but in certain cases as much as +185 g C m-2 per year.Our results emphasize the need to standardize gap filling-methods for improving the comparability of flux data products from regional and global flux networks. (C) 2001 Elsevier Science B.V. All rights reserved.

KW - Vindenergi og atmosfæriske processer

U2 - 10.1016/S0168-1923(00)00225-2

DO - 10.1016/S0168-1923(00)00225-2

M3 - Journal article

SN - 0168-1923

VL - 107

SP - 43

EP - 69

JO - Agricultural and Forest Meteorology

JF - Agricultural and Forest Meteorology

IS - 1

ER -

Gap filling strategies for defensible annual sums of net ecosystem exchange

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