1. Monitoring of Eyjafjallajökull Ash Layer Evolution over Payerne- Switzerland with a Raman Lidar Todor Dinoev, Valentin Simeonov*, and Mark Parlange Swiss Federal Institute of Technology –Lausanne (EPFL), Switzerland Bertrand Calpini MeteoSwiss – Payerne, Switzerland

2. Outlook General lidar principle Raman lidar for water vapor, temperature and aerosol measurements MeteoSwiss-EPFL lidar (RALMO –Raman Lidar for Meteorological Observation) Eyjafjallajöekull ash layer observation Conclusion

3. Lidar principle P I(z) z R A Laser Telesccope Spectral unit

4. Raman lidar Water vapor H2OH2O N2N2 O2O2 Laser

6. Temperature and aerosol measurements by the PRR S El

7. Laser Laser Power Supply Water Vapor Polychromator Aerosol / Temperature Polychromator Lidar Windows Laser Beam Telescope array Beam Expander 2005 mm Laser -400 mJ/pulse at 355 nm 30 Hz rep. rate Telescope-array of four 30 cm F#3 mirrors Polychromators- Grating based for water vapor and temperature Telescope / polychromators fiber coupled RALMO design

8. Inside view Fibers Output lens of the Beam Expander Mirrors Telescope Laser H 2 O Polychromator T° Polychromator

9. RALMO specifications Distance range 150 m-up to 5 km day/ 12km night Temporal resolution 30 min (optional 10 min) Spatial resolution - variable 15-300 m Detection limit water vapor 0.05 g/kg Temperature resolution 0.5 K Aerosol extinction and backscatter coefficients at 355 nm Statistical error < 10 % Automatic operation and data treatment Eye safe Operation Water vapor channel -Experimental operation since 2007 -Fully operational since 2008 Temperature/aerosol channel operational since 2009

10. Eyjafjallajöekull ash layer observations

11. Backscatter/water vapor MR 16 April17 April18 April

12. Backscatter/Relative humidity

13. Backtrajectories

14. Ash layer over Zurich Observation by ETHZ lidar (Thomas Peter)

15. Mass concentration

16. Conclusion Automated water vapor lidar for meteorological applications developed The lidar is in continuous operation from November 2007 at the aerological station of MeteoSwiss in Payerne. The data is regularly intercompared with SnowWhite and RS 92 sondes microwave radiometer, and GPS measurements. The lidar was upgraded with PRR channels for temperature, aerosol extinction and backscatter profiling Appearance and evolution of volcanic ash layer observed Optical properties measured and mass concentration estimated Anti correlation between aerosol load and water vapor mixing ratio observed

17. Thank you todor.dinoev@gmail.comtodor.dinoev@gmail.com or valentin.simeonov@epfl.ch

18. Transciever RALMO Transmitter Nd:YAG laser 400 mJ & 355 nm 30 Hz rep. rate Beam expander 15 X Receiver Matrix telescope of four mirrors 30 cm in diameter 0.2 mrad FOV

19. Time resolution - 10 min, Vertical resolution - 30 m up to 4 km No smooth or interpolation High pressure – Anticyclone ‘Rain stop’ Clouds/Fog < 500 m Clouds, Rain