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Some velocity and momentum‐flux statistics derived from transosonde flights
Author(s) -
Angell J. K.
Publication year - 1964
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.49709038609
Subject(s) - geostrophic wind , geology , zonal and meridional , latitude , atmospheric sciences , middle latitudes , eddy , flux (metallurgy) , meridional flow , angular momentum , climatology , geodesy , physics , meteorology , turbulence , classical mechanics , materials science , metallurgy
The wind speeds derived from 300 and 250 mb constant‐level balloon (transosonde) flights from Japan are found to be significantly greater than the wind speeds obtained from rawins and the geostrophic or gradient winds obtained from synoptic maps. This is partly due to a bias in the conventional data and perhaps partly due to horizontal entrainment of the transosondes into the jet‐stream core. Products of 2‐hour average zonal and meridional, geostrophic and ageostrophic velocity components obtained from transosonde trajectories indicate a northward ageostrophic flux of angular momentum in middle latitudes equal to about one‐fourth of the geostrophic flux. the product of 12‐hour average vertical and zonal velocity components indicates an upward flux of angular momentum in middle latitudes at 300 and 250 mb, thus implying that the downward flux of angular momentum in these latitudes is maintained by relatively small‐scale eddies. Temperature changes along transosonde trajectories suggest that on the average there is upward air motion on the ridges and downward air motion in the troughs. In conjunction with the mean position in the ridge‐trough pattern of the maximum ageostrophic flow to north and south, an indirect circulation in the meridional plane (Ferrel Cell) is postulated for middle latitudes.