Monitoring of Eyjafjallajökull Ash Layer Evolution over Payerne- Switzerland with a Raman Lidar

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 R z I(z) P Spectral unit Laser A Telesccope

4. Water vapor Laser Raman lidar N2 H2O O2

6. Temperature and aerosol measurements by the PRR SEl

7. RALMO design Lidar Windows Laser Beam Aerosol / Temperature Polychromator Water Vapor Polychromator Telescope array Beam Expander Laser Power Supply Laser 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

8. Fibers Output lens of the Beam Expander Fibers Mirrors Inside view Telescope T° Polychromator Telescope H2O Polychromator Laser

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 April 17 April 18 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.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 Clouds, Rain ‘Rain stop’Clouds/Fog < 500 m