Mountain polar stratospheric cloud measurements by ground based FTIR solar absorption spectroscopy

An analysis of mountain polar stratospheric cloud observations by solar absorption FTIR from Kiruna/Sweden was performed and compared with co-located airborne lidar measurements, The infrared cloud spectral signature and optical depth indicated water ice particles compatible with the high backscatter and depolarization ratio of the lidar signal. Retrieval of mean particle properties from the FTIR spectrum depend on the assumed width of the particle size distribution and range from 2.0 to 1.1 μum radius anti from 1.9 to 5.1 cm^-3 number density. The volume density is well determined with 63.8-60.2 μum³/cm³ equivalent to about 2.5 ppmv of condensed water at 20 hPa. Simulations of lidar backscatter ratio based on these results are consistent with the lidar observations.