TY  - JOUR
A1  - Osterloh, Lukas
A1  - Böckmann, Christine
A1  - Nicolae, Doina
A1  - Nemuc, Anca
T1  - Regularized inversion of microphysical atmospheric particle parameters -  theory and application
JF  - Journal of computational physics
N2  - Retrieving the distribution of aerosols in the atmosphere via remote sensing techniques is a highly complex task that requires dealing with a wide range of different problems stemming both from Physics and Mathematics. We focus on retrieving this distribution from multi-wavelength lidar data for aerosol ensembles consisting of spherical particles via an iterative regularization technique. The optical efficiencies for spherical scatterers are examined to account for the behavior of the underlying integral equation. The ill-posedness of the problem and the conditioning of the discretized problem are analyzed. Some critical points in the model, like the assumed wavelength-independence of the refractive index and the fixed grid of investigated refractive indices, are studied with regard to their expected impact on the regularized solution. A new Monte-Carlo type method is proposed for retrieval of the refractive index. To validate the results, the developed algorithm is applied to two measurement cases of burning biomass gained from multi-wavelength Raman lidar.
KW  - Inverse ill-posed problem
KW  - Regularization
KW  - Lidar remote sensing
KW  - Microphysical particle properties
Y1  - 2013
U6  - https://doi.org/10.1016/j.jcp.2012.11.040
SN  - 0021-9991
VL  - 237
IS  - 11
SP  - 79
EP  - 94
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - GEN
A1  - Osterloha, Lukas
A1  - Böckmann, Christine
A1  - Nicolae, Doina
A1  - Nemuc, Anca
T1  - Regularized inversion of microphysical atmospheric particle parameters: Theory and application (vol 237, pg 79, 2013)
T2  - Journal of computational physics
Y1  - 2014
U6  - https://doi.org/10.1016/j.jcp.2014.07.041
SN  - 0021-9991
SN  - 1090-2716
VL  - 275
SP  - 696
EP  - 696
PB  - Elsevier
CY  - San Diego
ER  - 
TY  - JOUR
A1  - Samaras, Stefanos
A1  - Nicolae, Doina
A1  - Böckmann, Christine
A1  - Vasilescu, Jeni
A1  - Binietoglou, Ioannis
A1  - Labzovskii, Lev
A1  - Toanca, Florica
A1  - Papayannis, Alexandros
T1  - Using Raman-lidar-based regularized microphysical retrievals and Aerosol Mass Spectrometer measurements for the characterization of biomass burning aerosols
JF  - Journal of computational physics
N2  - In this work we extract the microphysical properties of aerosols for a collection of measurement cases with low volume depolarization ratio originating from fire sources captured by the Raman lidar located at the National Institute of Optoelectronics (INOE) in Bucharest. Our algorithm was tested not only for pure smoke but also for mixed smoke and urban aerosols of variable age and growth. Applying a sensitivity analysis on initial parameter settings of our retrieval code was proved vital for producing semi-automatized retrievals with a hybrid regularization method developed at the Institute of Mathematics of Potsdam University. A direct quantitative comparison of the retrieved microphysical properties with measurements from a Compact Time of Flight Aerosol Mass Spectrometer (CToF-AMS) is used to validate our algorithm. Microphysical retrievals performed with sun photometer data are also used to explore our results. Focusing on the fine mode we observed remarkable similarities between the retrieved size distribution and the one measured by the AMS. More complicated atmospheric structures and the factor of absorption appear to depend more on particle radius being subject to variation. A good correlation was found between the aerosol effective radius and particle age, using the ratio of lidar ratios (LR: aerosol extinction to backscatter ratios) as an indicator for the latter. Finally, the dependence on relative humidity of aerosol effective radii measured on the ground and within the layers aloft show similar patterns. (C) 2015 Elsevier Inc. All rights reserved.
KW  - Aerosols
KW  - Microphysical properties
KW  - Lidar
KW  - AMS
KW  - AERONET
Y1  - 2015
U6  - https://doi.org/10.1016/j.jcp.2015.06.045
SN  - 0021-9991
SN  - 1090-2716
VL  - 299
SP  - 156
EP  - 174
PB  - Elsevier
CY  - San Diego
ER  -