UFAM Ozone and Aerosol Lidar


Geraint Vaughan, Emily Norton, Dave Wareing, Hugo Ricketts

The five wavelength ozone profiler is a compact stand alone differential absorption lidar (DIAL) system designed by Elight uses a Continuum PL8020 Nd:YAG laser in conjunction with a multiplexer to pump Raman shifting cells to produce wavelengths of 266, 289, 299, 316 and 315 nm. The wavelengths 289 nm, 299 nm and 316 nm are generated by stimulated Raman scattering in three respective Raman cells. The 266 nm light beam of the laser pumps the Raman gas cells sequentially by means of a continuously triggering multiplexer. These beams are expanded and emitted into the atmosphere. Backscattered light is collected in a double-coaxial 40 cm diameter telescope allowing measurements in both the near and far field and detected using analogue photo-multiplier tubes.

The system uses five wavelength beams in the UV region two 'on' and three 'off' the absorption cross-section of ozone . The attenuation at these wavelengths is measured and used to calculate the vertical distribution of ozone and aerosols up to altitudes of ~5 km.

Contents.

Schematic of the five wavelength lidar designed by Elight lasers.

The Ozone and Aerosol lidar at Writtle.

Operation requirements

Length x width 5 x 1.9 m
Weight ~ < 3 tonne
Dismantling time ~ 2 hours
Set-up time ~ 1 day
Power requirements Single phase 230 V 64 A

Three phase

Specifications of the 5 wavelength lidar

Ozone Measurement accuracy ~ 2 ppb
Range (dependent on atmospheric conditions) 200 m to 5 km
Altitude resolution
200 m below 2 km
600 m above 2 km
Specifications of the Nd:YAG continuum 8020 laser
Repetition rate 20 Hz
Energy
  • 1200 mJ @ 1064 nm
  • 550 mJ @ 532 nm
  • 300 mJ @ 355 nm
  • 80 mJ @ 266 nm
Pulsewidth
  • 6-8 ns @1064
  • 5-7 ns @266, 355, 532 nm
Divergence 0.45 mrad
Pointing stability 30 microrad
Power requirements 220-240 V, 50/60 Hz, 15 Amps, single phase
cooling requirements 4-8 l/min @ 3-4 bar, 22.3 Co max

Sample backscatter lidar data from the 10th August 2003

The absorption cross-section of ozone with the emitted wavelengths superimposed (wavelengths ‘on’ marked in red and ‘off’ marked in green)

Maintained by: Emily Norton