2 research outputs found
The PROUST radar: First results
Two campaigns took place in 1984 with the PROUST Radar operating in a bistatic mode, the transmitting antenna pointing at the vertical and the receiving one, 1 deg. off the vertical axis. The antenna beam intersection covers an altitude range between 3 and 9 km. The first of these campaigns are analyzed. The results analyzed show the capability of the PROUST Radar to measure the turbulent parameters and study the turbulence-wave interaction. In its present configuration (bistatic mode and 600 m vertical resolution), it has been necessary to make some assumptions that are known not to be truly fulfilled: homogeneous turbulence and constant vertical wind intensity over a 600-m thickness. It is clear that a more detailed study of the interaction between wave and turbulence will be possible with the next version of PROUST Radar (30-m altitude resolution and monostatic mode) that will soon be achieved
UHF radar observation of strato-tropospheric transfers on the anticyclonic side of a jet streak
An observation by UHF ST radar of a
subsidence pattern on the right side of the exit region of a jet streak is
reported. The onset of the subsidence pattern occurred at 23:30 UTC on the 29
November 1991, when a downward motion was initiated above 14 km. The injections
of stratospheric air in this region seem to have an intermittent nature; they
occur during at least three intervals during the lifetime of the subsidence
pattern. Comparison of these results with an ECMWF analysis suggests that it is
an unfolding case. However, observation of turbulent intensities w'
greater than 60 cm s–1 at the tropopause level also suggests the
existence of a turbulent flux between the stratosphere and the troposphere. From
the turbulence characteristics measured by the radar and the potential
temperature profile obtained by radiosonde data, the eddy diffusivity at the
tropopause level has been calculated. An eddy diffusion coefficient ranging
between 5 and 7 m2 s–1 is found. From these values, and
with the assumption of a climatological gradient of the volume mixing ratio of
ozone in the lower stratosphere, it is possible to deduce a rough estimate of
the amount of ozone injected from the stratosphere into the troposphere during
this event. A rate of transfer of 1.5×1020 molecules of ozone per
day and per square meter is found