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Structural analysis of airborne flux estimates over a regionAircraft-based observations of turbulence fields of velocity, moisture, and temperature are used to study coherent turbulent structures that dominate turbulent transfer of moisture and heat above three different eco-systems. Flux traces are defragmented, to reconstruct the presumed full size (along the sampled transect) of these structures, and flux traces are simplified by elimination of those that contribute negligibly to the flux estimate. Structures are analyzed in terms of size, spatial distribution, and contribution to the flux, in the four 'quadrant' modes of eddy-covariance transfer (excess up/down and deficit up/down). The effect of nonlinear detrending of moisture and temperature data on this 'structural analysis,' over surfaces with heterogeneous surface wetness, is also examined. Results over grassland, wetland, and moist and dry agricultural land, show that nonlinear detrending may provide a more physically realistic description of structures. Significant differences are observed between structure size and associated relative flux contribution, between moist and dry areas, with smaller structures playing a more important role over the moist areas. Structure size generally increases with height, as spatial reorganization from smaller structures into larger ones takes place. This coincides with a gradual loss of surface 'signature' (position and clustering of plumes above localized source areas). The data are expected to provide a basis for an eventual statistical description of boundary-layer transfer events , and help to interpret the link between boundary-layer transfer and hydrological surface conditions.
Document ID
19940038992
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Caramori, Paulo
(McGill Univ. Macdonald Campus, Montreal, Quebec, Canada)
Schuepp, Peter
(McGill Univ. Macdonald Campus, Montreal, Quebec, Canada)
Desjardins, Raymond
(Centre of Land and Biological Resources Ottawa, Canada)
Macpherson, Ian
(National Research Council of Canada Ottawa, Canada)
Date Acquired
August 16, 2013
Publication Date
May 1, 1994
Publication Information
Publication: Journal of Climate
Volume: 7
Issue: 5
ISSN: 0894-8755
Subject Category
Meteorology And Climatology
Accession Number
94A62441
Distribution Limits
Public
Copyright
Other

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