KARL: KOLDEWEY AEROSOL RAMAN LIDAR
KARL observation (Ny Ålesund)
Purpose of Participation
- Establish link between optical and microphysical parameters and validate specific data reduction algorithms
- Monitor occurrence of aerosol over Ny-Ålesund
Instrument description
Light of a pulsed laser is backscattered by particles in the troposphere. Profiles of backscatter coefficients (m-1 sr-1) and extinction coefficients (m-1) can be measured by time delay when backscattered light meets detector via velocity of light. Single scattering is to be assumed (no cloud measurements). Using an inversion code real and imaginary part of index of refraction and, in a second step, particle size distribution can be derived.
| Species | Aerosols (vertical profile) |
| Method | Measure photons which are backscattered in atmosphere versus time of pulsed laser |
| Quantity primary | Backscatter and extinction coefficients profiles |
| Quantity secondary | in case of spherical particles: index of refraction (real + imaginary part); mean particle size; size distribution |
| Spectral range | 355 nm to 1064 nm |
| Altitude range | Backscatter: 400 m to 8 km / extinction:400 m to 5 km |
| Vertical resolution | 60 m |
| Temporal resolution | Backscatter: 10 minutes / extinction:1 h |
| Operation | Operation always under clear sky conditions |
| Precision | ± 10% |
| Data availability (during campaign) | Next day |
| Final data (after campaign) | Three months |
Specific remarks
- Confirmation by photometers, particle counters and information about aerosol-scattering is planned.
References
Schumacher, R.,Neuber, R.,Herber, A.,Rairoux, P.,Schrems, O.(2001). Extinction profiles measured with a Raman Lidar in the Arctic troposphere, Advances in Laser Remote Sensing - selected papers, presented at the 20th ILRC, Vichy, France 10 - 14th July 2000", Editors : A. Dabas, C. Loth, J. Pelon; Edition de l'Ecole polytechnique, 229 - 232.
Schumacher, R.(2001). Messung von optischen Eigenschaften troposphärischer Aerosole in der Arktis, Berichte zur Polar- und Meeresforschung, 386 (2001), Universität Potsdam.