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Dual‐scale transport of sensible heat and water vapor over a short canopy under unstable conditions
Author(s) -
Saito Makoto,
Asanuma Jun,
Miyata Akira
Publication year - 2007
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr005136
Subject(s) - mesoscale meteorology , eddy covariance , sensible heat , turbulence , water vapor , environmental science , atmospheric sciences , meteorology , advection , mechanics , flux (metallurgy) , geology , physics , materials science , thermodynamics , ecology , ecosystem , metallurgy , biology
This study examines the nature of vertical transport of sensible heat and water vapor density due to mesoscale motions and how they are observed with surface eddy covariance systems. For this purpose, turbulence data measured above a flat and irrigated rice paddy field under unstable conditions were analyzed. It was shown that the larger‐scale component in the measured time series represents mesoscale motions. Wavelet cospectra of the scalar fluxes revealed the presence of vertical transport at horizontal scales larger than the cospectral gap. A time series and the eddy covariance flux were decomposed into a turbulence and a mesoscale component using the identified cospectral gap. The mesoscale transport component of sensible heat and water vapor were found to be related to the wind direction and therefore characteristic of the upwind surface conditions at this scale. In contrast, the turbulence flux component exhibits universal attributes resulting from the local surface characteristics.