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Velocity spectra and cospectra and integral statistics over Arctic leads
Author(s) -
Andreas Edgar L.,
Paulson Clayton A.
Publication year - 1979
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49710544621
Subject(s) - spectral line , physics , anisotropy , computational physics , optics , astronomy
From the high frequency velocity measurements of the AIDJEX Lead Experiment we derive estimates of u and w spectra and uw cospectra both above Arctic leads and over relatively smooth pack ice. The measurements over the leads are unique for two reasons: they were made within a geophysical internal boundary layer (IBL) resulting from a large step change in surface temperature; and all were made within 50cm of the surface. The intense mixing within the IBL and the nearness of the measurements to the surface affect the shapes of all the over‐lead spectra and cospectra. The u and w spectra have rounded peaks and no inertial subrange. The cospectra contain substantial energy at frequencies typically in the inertial subrange. Coherence spectra are greater than zero out to nondimensional frequencies of order ten. Despite the anisotropy of their origin, however, normalized spectra and cospectra plotted against the nondimensional frequency fz/U and grouped according to Reynolds number collapse into single curves. The integral statistics ( w 2 / − uw )1/2 and ( u 2 / − uw )1/2 have values smaller than those usually reported, as a consequence of both the mixing and the low measurement height.