Geoscience Reference
In-Depth Information
Fig. 9 shows a measurement result around the cloud top. In the upper part of clouds, an
increase of spectral width up to 0.5-0.7 m s
-1
, which indicates the presence of small-scale
turbulence triggered by convective instabilities, is observed (Fig. 9c). Further, in the top part
of clouds (0-500 m below the cloud tops), downward wind
up to 0.2-0.3 m s
-1
, which was
caused by radiative cooling, was observed. For further discussion on the generation
mechanism of turbulence, see Yamamoto et al. (2009a). From a case study using data
measured by the MU radar and Raman/Mie lidar, Yamamoto et al. (2009b) showed a clear
relation between the cloud-top altitude of mid-latitude cirrus and the bottom altitude of
subtropical jet with high time and altitude resolutions (12 min and 150 m, respectively).
Fig. 9. Time-altitude plots of (a) backscattered power measured by a 532-nm Mie lidar, and
(b) vertical wind velocity and (c) spectral width measured by the vertical beam of the EAR
(Yamamoto et al., 2009a). Thick black curves in each panel indicate cloud boundaries
estimated by the lidar backscattered power.
3.3 Other measurements
Measurements using wind profiling radars and other instruments are not limited to cloud
researches. Measurement results of stratosphere-troposphere exchange (STE) processes have
been reported in the last decade. Using observation network of wind profiling radar and
lidar, Bertin et al. (2001) showed details of turbulent generation above and below the jet axis
associated with a tropopause folding in the middle latitude. Using measurement data
collected by the MU radar and ozonesonde, Gavrilov et al. (2006) compared distribution of
turbulent diffusivity with vertical ozone flux. It is well known that clear-air echo power
showed a vertical increase around the tropopause due to the increase of static stability or
turbulence intensity (see section 14 of Hocking, 2011). Using data collected by the intensive
observation of wind profiling radars and ozonesonde at Canada, Hocking et al. (2007)
showed that stratospheric ozone has impacts on tropospheric ozone by its downward
