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Air motion within Kelvin‐Helmholtz billows determined from simultaneous Doppler radar and aircraft measurements
Author(s) -
Browning K. A.,
Bryant G. W.,
Starr J. R.,
Axford D. N.
Publication year - 1973
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.49709942203
Subject(s) - geology , vortex , clear air turbulence , radar , turbulence , physics , meteorology , wind shear , vorticity , geodesy , mechanics , wind speed , aerospace engineering , engineering
A new linked mode of operation has been used to obtain virtually simultaneous measurements by a fully instrumented aircraft and a ground‐based high power radar within a train of large amplitude Kelvin‐Helmholtz billows in the optically clear atmosphere. Both sets of data were analysed to show the detailed distribution of air motion and turbulence within the billows. The resulting pattern was consistent with a train of vortices each of which was characterized by a vertical wind shear of 6 m s −1 over 100 m, with downward motion of about 1 m s −1 on the downshear side and upward motion of about 1 m s −1 on the upshear side. Between the vortices the vertical shear decreased to almost half the maximum value. The most intense radar echoes occurred within inclined layers connecting the top of one region of maximum vorticity to the bottom of the next. The aircraft, which flew through the upper parts of the billows, encountered turbulence of up to moderate intensity as it penetrated the crests of the billows. Between successive penetrations of the billow crests the aircraft flew close to but just above the region of intense radar echo and encountered smooth air with a slowly varying vertical component of motion.