References

Biogeosciences

1726-4189

Copernicus Publications

Göttingen, Germany

10.5194/bg-7-301-2010

Heat storage in forest biomass improves energy balance closure

Lindroth

¹ Mölder

¹ Lagergren

Lund University, Geobiosphere Science Centre, Physical Geography and Ecosystems Analysis, Sölvegatan 12, 22362 Lund, Sweden

21 01 2010

7 1 301 313

2010

This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/

This article is available from https://bg.copernicus.org/articles/7/301/2010/bg-7-301-2010.html

The full text article is available as a PDF file from https://bg.copernicus.org/articles/7/301/2010/bg-7-301-2010.pdf

Temperature measurements in trunks and branches in a mature ca. 100 years-old mixed pine and spruce forest in central Sweden were used to estimate the heat storage in the tree biomass. The estimated heat flux in the sample trees and data on biomass distributions were used to scale up to stand level biomass heat fluxes. The rate of change of sensible and latent heat storage in the air layer below the level of the flux measurements was estimated from air temperature and humidity profile measurements and soil heat flux was estimated from heat flux plates and soil temperature measurements. The fluxes of sensible and latent heat from the forest were measured with an eddy covariance system in a tower. The analysis was made for a two-month period in summer of 1995. The tree biomass heat flux was the largest of the estimated storage components and varied between 40 and −35 W m−2 on summer days with nice weather. Averaged over two months the diurnal maximum of total heat storage was 45 W m−2 and the minimum was −35 W m−2. The soil heat flux and the sensible heat storage in air were out of phase with the biomass flux and they reached maximum values that were about 75% of the maximum of the tree biomass heat storage. The energy balance closure improved significantly when the total heat storage was added to the turbulent fluxes. The slope of a regression line with sum of fluxes and storage as independent and net radiation as dependent variable, increased from 0.86 to 0.95 for half-hourly data and the scatter was also reduced. The most significant finding was, however, that during nights with strongly stable conditions when the sensible heat flux dropped to nearly zero, the total storage matched the net radiation very well. Another interesting result was that the mean energy imbalance started to increase when the Richardson number became more negative than ca. −0.1. In fact, the largest energy deficit occurred at maximum instability. Our conclusion is that eddy covariance measurements can function well during stable conditions but that the functioning under strong instabilities might be a so far unforeseen problem.

References 1

Abramowitz, M. and Stegun, I. A.: Handbook of mathematical functions, National Bureau of Standards, Applied Mathematics Series, 55, 1046 pp., 1965.

Anonymous: Praktisk Skogshandbok, Sveriges Skogsvårdsförbund, Djursholm, 510 pp., 1994.

Aston, A. R.: Heat storage in a young Eucalypt forest, Agr. Forest Meteorol., 35, 281–297, 1985.

Aubinet, M., Grelle, A., Ibrom, A., Rannik, Ü., Moncrieff, J., Foken, T., Kowalski, A. S., Martin, P. H., Berbigier, P., Bernhofer, C., Clement, R., Elbers, J., Granier, A., Grunwald, T., Morgenstern, K., Pilegaard, K., Rebmann, C., Snijders, W., Valentini, R., and Vesala, T.: Estimates of the annual net carbon and water exchange of forests: The EUROFLUX methodology, Adv. Ecol. Res., 30, 113–175, 2002.

Barr, A. G., Morgenstern, K., Black, T. A., McCaughey, J. H., and Nesic, Z.: Surface energy balance closure by the eddy-covariance method above three boreal forest stands and implications for the measurement of the CO2 flux, Agr. Forest Meteorol., 140, 322–337, 2006.

Cava, D., Contini, D, Donateo, A., and Martano, P.: Analysis of short-term closure of the surface energy balance above short vegetation, Agr. Forest Meteorol., 148, 82–93, 2008.

Foken, T.: The energy balance closure problem: An overview, Ecol. Appl., 18(6), 1351–1367, 2008.

Gash, J. H. C. and Dolman, A. J.: Sonic anemometer (co)sine response and flux measurement I., The potential for (co)sine error to affect sonic anemometer-based flux measurements, Agr. Forest Meteorol., 119, 195–207, 2003.

Foken, T., Wimmer, F., Mauder, M., Thomas, C., and Liebethal, C.: Some aspects of the energy balance closure problem, Atmos. Chem. Phys., 6, 4395–4402, 2006.

Grelle, A.: Long term water and carbon dioxide fluxes from a boreal forest, Acta Universitatis Agriculturae Sueciae, Silvestria 28, 80 pp., 1994.

Grelle, A. and Lindroth, A.: Eddy-correlation system for long term monitoring of fluxes of heat, water vapour, and CO2, Glob. Change Biol., 2, 297–307, 1996.

Håkansson, J. and Körling, A.: Uppskattning av mängden kol i trädform – en metodstudie, Department of Physical Geography, Lund University, Diploma Thesis No. 86, 2002.

Guyot, G.: Physics of the Environment and Climates, John Wiley & Sons Ltd, 1998.

Halldin, S. and Lindroth, A.: Errors in net radiometry: Comparison and evaluation of six radiometer designs, J. Atmos. Ocean. Tech., 9(6), 762–783, 1992.

Kanda, M., Inagaki, A., Letzel, M. O., Raasch, S., and Watanabe, T.: LES studies of the energy imbalance problem with eddy covariance fluxes, Boundary-Layer Meteorology, 110, 381–404, 2004.

Lee, X.: On micrometeorological observations of surface-air exchange over tall vegetation, Agr. Forest Meteorol., 91, 39–50, 1998.

Lundblad, M. and Lindroth, A.: Transpiration of a coniferous forest in relation to weather and stand characteristics, Basic Appl. Ecol., 3, 229–243, 2002.

Lundin, L. C., Cienciala, E., Grelle, A., Halldin, S., Hjelm, P., Kellner, E., Lindroth, A., Mölder, M., Lundberg, A., Moren, A.-S., Nord, T., Seibert, J., and Stähli, M.: Continuous long-term measurements of soil-plant-atmosphere variables at a forest site, Agr. Forest Meteorol., 98-99, 53–74, 1999.

Massman, W. J. and Lee, X.: Eddy covariance flux corrections and uncertainties in long-term studies of carbon and energy exchanges, Agr. Forest Meteorol., 113, 121–144, 2002.

McCaughey, J. H. and Saxton, W. L.: Energy balance storage terms in a mixed forest, Agr. Forest Meteorol., 44, 1–18, 1988.

McCaughey, J. H., Lafleur, P. M., Joiner, D. W., Bartlett, P. A., Costello, A. M., Jelinski, D. E., and Ryan, M. G.: Magnitudes and seasonal patterns of energy, water and carbon exchanges at a boreal young jack pine forest in the BOREAS northern study area, J. Geophys. Res., 102(D24), 28997–29007, 1997.

Meesters, A. G. C. A. and Vugts, H. F.: Calculation of heat storage in stems, Agr. Forest Meteorol., 78, 181–202, 1996.

Moderow, U., Aubinet, M., Feigenwinter, C., Kolle, O., Lindroth, A., Mölder, M., Montaganai, L., Rebman, C., and Bernhofer, C.: Available energy and energy balance closure at four coniferous forest sites across Europe, Theor. Appl. Climatol., 98, https://doi.org/10.1007/s00704-009-0175-0, 2010.

Moore, C. J. and Fisch, G.: Estimating heat storage in Amazonian tropical forest, Agr. Forest Meteorol., 38, 147–169, 1986.

Mölder, M., Lindroth, A., and Halldin, S.: Water vapor, CO2, and temperature profiles in and above a forest – accuracy assessment of an unattended measurement system, J. Atmos. Ocean. Technol., 17(4), 417–425, 2000.

Näslund, M.: Functions and tables for computing the cubic volume of standing trees, Meddelanden från Statens skogsforskningsinstitut, 36, 3, Stockholm, 81 pp., 1947.

Oliphant, A. J., Grimmond, C. S. B., Zutter, H. N., Schmid, H. P., Su, H.-B., Scott, S. L., Offerle, B., Randolph, J. C., and Ehman, J.: Heat storage and energy balance fluxes for a temperate deciduous forest, Agr. Forest Meteorol., 126, 185–201, 2004.

Paw, U. K. T., Baldocchi, D., Meyers, T. P., and Wilson, K. B.: Correction of eddy-covariance measurements incorporating both advection effects and density fluxes, Agr. Forest Meteorol., 97, 487–511, 2000.

Roupsard, O., Bonnefond, J.-M., Irvine, M., Berbigier, P., Nouvellon, Y., Dauzat, J., Taga, S., Hamel, O., Jourdan, C., Saint-Andre, L., Mialet-Serra, I., Labouisse, J.-P., Epron, D., Joffre, R., Braconnier, S., Rouziere, A., Navarro, M., and Bouillet, J.-P.: Partitioning energy and evapo-transpiration above and below a tropical palm canopy, Agr. Forest Meteorol., 139, 252–268, 2006.

dos Santos Michiles, A. A. and Gielow, R.: Above-ground thermal energy storage rates, trunk heat fluxes and surface energy balance in a central Amazonian rainforest, Agr. Forest Meteorol., 148, 917–930, 2008.

Schmid, H. P.: Experimental design for flux measurements: matching scales of observations and fluxes, Agr. Forest Meteorol., 87, 179–200, 1997.

Tanaka, H., Hiyama, T., Kobayashi, N., Yabuki, H., Ishii, Y., Desyatkin, R. V., Maximov, T. C., and Ohta, T.: Energy balance and its closure over a young larch forest in eastern Siberia, Agr. Forest Meteorol., 148, 1954–1967, 2008.

Twin, T. E., Kustas, W. P., Norman, J. M., Cook, D. R., Houser, P. R., Meyers, T. P., Prueger, J. H., Starks, P. J., and Wesely, M. L.: Correcting eddy-covariance flux estimates over grassland, Agr. Forest Meteorol., 103, 279–300, 2002.

Van der Molen, M. K., Gash, J. H. C., and Elbers, J. A.: Sonic anemometer (co)sine response and flux measurement II. The effect of introducing an angle of attack dependent calibration, Agr. Forest Meteorol., 122, 95–109, 2004.

Wilson, K., Goldstein, A., Falge, E., Aubinet, M., Baldocchi, D., Berbigier, P., Bernhofer, C., Ceulemans, R., Dolman, H., Field, C., Grelle, A., Ibrom, A., Law, B. E., Kowalski, A., Meyers, T., Moncrieff, J., Monson, R., Oechel, W., Tenhunen, J., Valentini, R., and Verma, S.: Energy balance closure at FLUXNET sites, Agr. Forest Meteorol., 113, 223–243, 2002.

Wolf, A., Saliendra, N., Akshalov, K., Johnson, D. A., and Laca, E.: Effects of different eddy covariance correction schemes on energy balance closure and comparison with the modified Bowen ratio system, Agr. Forest Meteorol., 148, 942–952, 2008.