A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites.

C.R. Lloyd, P. Bessemoulin, F.D. Cropley, A.D. Culf, A.J. Dolman, J. Elbers, J. Moncrieff, B. Monteny, A. Verhoef

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

The variability between surface flux measurements at the fallow sites of the three HAPEX-Sahel supersites is examined over periods of three or four consecutive days. A roving eddy correlation instrument provided a common base for comparison at each supersite. The inhomogeneity of the surface and the instrumental layout did not provide the conditions to allow the separation of the effects of instrument error from those due to the spatial variability of vegetation cover and soil moisture. Surface fluxes of sensible and latent heat and energy balance terms were intercompared at each supersite over summation timescales of 1 hour and 3 days. It is shown that, generally, HAPEX-Sahel hourly sensible heat flux and latent heat values have confidence limits of 15% and 20% respectively. The three-day period energy balance shows the combined sensible and latent heat fluxes to have a confidence limit of 3%. It is concluded that, due to the averaging effect of longer time periods and larger flux footprints on spatial inhomogeneity, confidence in the surface flux measurements increases with longer summation periods and with neutral atmospheric surface layers which characterise the rainy period of the Intensive Observation Period.
Original languageEnglish
Pages (from-to)400-425
JournalJournal of Hydrology
Volume188-189
Issue number1-4
DOIs
Publication statusPublished - 1997

Fingerprint

surface flux
fallow
flux measurement
sensible heat flux
inhomogeneity
energy balance
heat balance
latent heat flux
footprint
vegetation cover
surface layer
eddy
soil moisture
timescale
comparison
effect

Keywords

  • microclimate
  • plants
  • boundaries
  • plant communities
  • vegetation
  • research
  • sahel

Cite this

Lloyd, C. R., Bessemoulin, P., Cropley, F. D., Culf, A. D., Dolman, A. J., Elbers, J., ... Verhoef, A. (1997). A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites. Journal of Hydrology, 188-189(1-4), 400-425. https://doi.org/10.1016/S0022-1694(96)03184-8
Lloyd, C.R. ; Bessemoulin, P. ; Cropley, F.D. ; Culf, A.D. ; Dolman, A.J. ; Elbers, J. ; Moncrieff, J. ; Monteny, B. ; Verhoef, A. / A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites. In: Journal of Hydrology. 1997 ; Vol. 188-189, No. 1-4. pp. 400-425.
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abstract = "The variability between surface flux measurements at the fallow sites of the three HAPEX-Sahel supersites is examined over periods of three or four consecutive days. A roving eddy correlation instrument provided a common base for comparison at each supersite. The inhomogeneity of the surface and the instrumental layout did not provide the conditions to allow the separation of the effects of instrument error from those due to the spatial variability of vegetation cover and soil moisture. Surface fluxes of sensible and latent heat and energy balance terms were intercompared at each supersite over summation timescales of 1 hour and 3 days. It is shown that, generally, HAPEX-Sahel hourly sensible heat flux and latent heat values have confidence limits of 15{\%} and 20{\%} respectively. The three-day period energy balance shows the combined sensible and latent heat fluxes to have a confidence limit of 3{\%}. It is concluded that, due to the averaging effect of longer time periods and larger flux footprints on spatial inhomogeneity, confidence in the surface flux measurements increases with longer summation periods and with neutral atmospheric surface layers which characterise the rainy period of the Intensive Observation Period.",
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Lloyd, CR, Bessemoulin, P, Cropley, FD, Culf, AD, Dolman, AJ, Elbers, J, Moncrieff, J, Monteny, B & Verhoef, A 1997, 'A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites.', Journal of Hydrology, vol. 188-189, no. 1-4, pp. 400-425. https://doi.org/10.1016/S0022-1694(96)03184-8

A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites. / Lloyd, C.R.; Bessemoulin, P.; Cropley, F.D.; Culf, A.D.; Dolman, A.J.; Elbers, J.; Moncrieff, J.; Monteny, B.; Verhoef, A.

In: Journal of Hydrology, Vol. 188-189, No. 1-4, 1997, p. 400-425.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites.

AU - Lloyd, C.R.

AU - Bessemoulin, P.

AU - Cropley, F.D.

AU - Culf, A.D.

AU - Dolman, A.J.

AU - Elbers, J.

AU - Moncrieff, J.

AU - Monteny, B.

AU - Verhoef, A.

PY - 1997

Y1 - 1997

N2 - The variability between surface flux measurements at the fallow sites of the three HAPEX-Sahel supersites is examined over periods of three or four consecutive days. A roving eddy correlation instrument provided a common base for comparison at each supersite. The inhomogeneity of the surface and the instrumental layout did not provide the conditions to allow the separation of the effects of instrument error from those due to the spatial variability of vegetation cover and soil moisture. Surface fluxes of sensible and latent heat and energy balance terms were intercompared at each supersite over summation timescales of 1 hour and 3 days. It is shown that, generally, HAPEX-Sahel hourly sensible heat flux and latent heat values have confidence limits of 15% and 20% respectively. The three-day period energy balance shows the combined sensible and latent heat fluxes to have a confidence limit of 3%. It is concluded that, due to the averaging effect of longer time periods and larger flux footprints on spatial inhomogeneity, confidence in the surface flux measurements increases with longer summation periods and with neutral atmospheric surface layers which characterise the rainy period of the Intensive Observation Period.

AB - The variability between surface flux measurements at the fallow sites of the three HAPEX-Sahel supersites is examined over periods of three or four consecutive days. A roving eddy correlation instrument provided a common base for comparison at each supersite. The inhomogeneity of the surface and the instrumental layout did not provide the conditions to allow the separation of the effects of instrument error from those due to the spatial variability of vegetation cover and soil moisture. Surface fluxes of sensible and latent heat and energy balance terms were intercompared at each supersite over summation timescales of 1 hour and 3 days. It is shown that, generally, HAPEX-Sahel hourly sensible heat flux and latent heat values have confidence limits of 15% and 20% respectively. The three-day period energy balance shows the combined sensible and latent heat fluxes to have a confidence limit of 3%. It is concluded that, due to the averaging effect of longer time periods and larger flux footprints on spatial inhomogeneity, confidence in the surface flux measurements increases with longer summation periods and with neutral atmospheric surface layers which characterise the rainy period of the Intensive Observation Period.

KW - microklimaat

KW - planten

KW - grenzen

KW - plantengemeenschappen

KW - vegetatie

KW - onderzoek

KW - sahel

KW - microclimate

KW - plants

KW - boundaries

KW - plant communities

KW - vegetation

KW - research

KW - sahel

U2 - 10.1016/S0022-1694(96)03184-8

DO - 10.1016/S0022-1694(96)03184-8

M3 - Article

VL - 188-189

SP - 400

EP - 425

JO - Journal of Hydrology

JF - Journal of Hydrology

SN - 0022-1694

IS - 1-4

ER -

Lloyd CR, Bessemoulin P, Cropley FD, Culf AD, Dolman AJ, Elbers J et al. A comparison of surface fluxes at the HAPEX-Sahel fallow bush sites. Journal of Hydrology. 1997;188-189(1-4):400-425. https://doi.org/10.1016/S0022-1694(96)03184-8