Development and application of a backscatter lidar forward operator for quantitative validation of aerosol dispersion models and future data assimilation
A new backscatter lidar forward operator was developed which is based on the distinct calculation of the aerosols' backscatter and extinction properties. The forward operator was adapted to the COSMO-ART ash dispersion simulation of the Eyjafjallajökull eruption in 2010. While the particle n...
| Main Authors: | , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-12-01
|
| Series: | Atmospheric Measurement Techniques |
| Online Access: | https://www.atmos-meas-tech.net/10/4705/2017/amt-10-4705-2017.pdf |
| Summary: | A new backscatter lidar forward operator was developed which is based on the
distinct calculation of the aerosols' backscatter and extinction properties.
The forward operator was adapted to the COSMO-ART ash dispersion simulation
of the Eyjafjallajökull eruption in 2010. While the particle number
concentration was provided as a model output variable, the scattering
properties of each individual particle type were determined by dedicated
scattering calculations. Sensitivity studies were performed to estimate the
uncertainties related to the assumed particle properties. Scattering
calculations for several types of non-spherical particles required the usage
of T-matrix routines. Due to the distinct calculation of the backscatter and
extinction properties of the models' volcanic ash size classes, the
sensitivity studies could be made for each size class individually, which is not the case for forward
models based on a fixed lidar ratio. Finally, the forward-modeled lidar
profiles have been compared to automated ceilometer lidar (ACL) measurements
both qualitatively and quantitatively while the attenuated backscatter
coefficient was chosen as a suitable physical quantity. As the ACL
measurements were not calibrated automatically, their calibration had to be
performed using satellite lidar and ground-based Raman lidar measurements. A
slight overestimation of the model-predicted volcanic ash number density was
observed. Major requirements for future data assimilation of data from ACL
have been identified, namely, the availability of calibrated lidar
measurement data, a scattering database for atmospheric aerosols, a better
representation and coverage of aerosols by the ash dispersion model, and more
investigation in backscatter lidar forward operators
which calculate the backscatter coefficient directly for each
individual aerosol type. The introduced forward operator offers the
flexibility to be adapted to a multitude of model systems and measurement
setups. |
|---|---|
| ISSN: | 1867-1381 1867-8548 |