The following plots show on top the 10 s averaged, range corrected backscatter signal at 1064 nm, which roughly shows the amount of particles in the atmosphere, and below the  volume linear depolarization ratio at 532 nm, i.e. the backscatter signal cross polarized to the linear laser polarization divided by the parallel polarized backscatter signal. The horizontal axis is the time (UTC), and the vertical axis the height above ground in km. The altitude in Maisach is 515 m NN. The temporal resolution of the measurements is 1/(10 seconds), and the height resolution increases between 7.5 m near ground to some hundred meters at 16 km. The noise in the upper part of the depolarization plots during day stems from the skylight background. Depolarization plots have a slightly different height averaging than the backscatter plots because of the higher noise level, which can sometimes give the impression of multiple scattering effects. Please contact me for details.

Volcanic ash particles are strongly depolarizing, similar to mineral dust and ice crystals in cirrus clouds, and can hence often be identified by enhanced depolarization structures in the plots of this episode. The plot at right shows an example with areas very probably containing volcanic ash. However, as this discrimination technique for volcanic ash can be ambiguous, we use additional signals, which are not shown here, to achieve a high confidence level.

The animation for each day shows the same plots as below but overlayed and alternating between the volume linear depolarisation ratio and the range corrected signal. In this way the depolarising (volcanic ash, cirrus, Saharan dust) layers can better be identified. The animated plots are horizontally compressed to fit on one page. The times and heights can be found on the full plots. The animations are Windows executable files and must be downloaded to your PC end executed. The animation can be stopped and restarted by pressing the space key, and when stopped the plots can manually be alternated by pressing the cursor left or right key. Leave the animation with the Esc key.  According to my daily updated virus scanner (Sophos) the files are free of viruses. However, I do not guarantee for any damage these files could do to your PC or to you. Use them at your own risk (I guess I have to say that...).

More plots,data, and info here and there.