caa a22 4500 475777514 CHVBK 20180406123635.0 cr unu---uuuuu 170329e20000201xx s 000 0 eng 10.1023/A:1002401829007 doi (NATIONALLICENCE)springer-10.1023/A:1002401829007 Turbulence Statistics Above And Within Two Amazon Rain Forest Canopies [Elektronische Daten] [B. Kruijt, Y. Malhi, J. Lloyd, A. Norbre, A. Miranda, M. Pereira, A. Culf, J. Grace] The turbulence structure in two Amazon rain forestswas characterised for a range of above-canopystability conditions, and the results compared withprevious studies in other forest canopies and recenttheory for the generation of turbulent eddies justabove forest canopies. Three-dimensional wind speedand temperature fluctuation data were collectedsimultaneously at up to five levels inside and abovetwo canopies of 30-40 m tall forests, during threeseparate periods. We analysed hourly statistics, jointprobability distributions, length scales, spatialcorrelations and coherence, as well as power spectraof vertical and horizontal wind speed. The daytime results show a sharp attenuation ofturbulence in the top third of the canopies, resultingin very little movement, and almost Gaussianprobability distributions of wind speeds, in the lowercanopy. This contrasts with strongly skewed andkurtotic distributions in the upper canopy. At night,attenuation was even stronger and skewness vanishedeven in the upper canopy. Power spectral peaks in thelower canopy are shifted to lower frequencies relativeto the upper canopy, and spatial correlations andcoherences were low throughout the canopy. Integrallength scales of vertical wind speed at the top of thecanopy were small, about 0.15 h compared to avalue of 0.28 h expected from the shear lengthscale at the canopy top, based on the hypothesis that theupper canopy air behaves as a plane mixing layer. Allthis suggests that, although exchange is not totallyinhibited, tropical rain forest canopies differ from other forests in that rapid, coherentdownward sweeps do not penetrate into the lowercanopy, and that length scales are suppressed. This isassociated with a persistent inversion of stability inthat region compared to above-canopy conditions. Theinversion is likely to be maintained by strong heatabsorption in the leaves concentrated near thecanopy top, with the generally weak turbulence beingunable to destroy the temperature gradients over thelarge canopy depth. Kluwer Academic Publishers, 2000 Tropical forest nationallicence Skewness nationallicence Turbulence spectra nationallicence Coupling nationallicence Length scales nationallicence Canopy inversion nationallicence Kruijt B. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K. aut Malhi Y. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K. aut Lloyd J. Environmental Biology Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, 0200, Canberra, ACT, Australia aut Norbre A. Instituto Nacional de Pesquisas da Amazonia, CPU78, 69011, Manaus, AM, Brazil aut Miranda A. Departamento de Ecologia, Universidade de Brasilia, DF-70910, Brazil aut Pereira M. Instituto Nacional de Pesquisas da Amazonia, CPU78, 69011, Manaus, AM, Brazil aut Culf A. Institute of Hydrology, Wallingford, OX10 8BB, Oxon, U.K. aut Grace J. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K. aut Boundary-Layer Meteorology Kluwer Academic Publishers 94/2(2000-02-01), 297-331 0006-8314 94:2<297 2000 94 10546 https://doi.org/10.1023/A:1002401829007 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1002401829007 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Kruijt B. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K aut NATIONALLICENCE 700 1- Malhi Y. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K aut NATIONALLICENCE 700 1- Lloyd J. Environmental Biology Group, Research School of Biological Sciences, Institute of Advanced Studies, Australian National University, 0200, Canberra, ACT, Australia aut NATIONALLICENCE 700 1- Norbre A. Instituto Nacional de Pesquisas da Amazonia, CPU78, 69011, Manaus, AM, Brazil aut NATIONALLICENCE 700 1- Miranda A. Departamento de Ecologia, Universidade de Brasilia, DF-70910, Brazil aut NATIONALLICENCE 700 1- Pereira M. Instituto Nacional de Pesquisas da Amazonia, CPU78, 69011, Manaus, AM, Brazil aut NATIONALLICENCE 700 1- Culf A. Institute of Hydrology, Wallingford, OX10 8BB, Oxon, U.K aut NATIONALLICENCE 700 1- Grace J. Institute of Ecology and Resource Management, University of Edinburgh, Darwin Building, Mayfield Road, EH9 3JU, Edinburgh, U.K aut NATIONALLICENCE 773 0- Boundary-Layer Meteorology Kluwer Academic Publishers 94/2(2000-02-01), 297-331 0006-8314 94:2<297 2000 94 10546 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer