Parallel software for retrieval of aerosol distribution from LIDAR data in the framework of EARLINET-ASOS

Osterloh, Lukas; García‐Pando, Carlos Pérez; Böhme, David; Baldasano, J. M.; Böckmann, Christine; Schneidenbach, Lars; Vicente, David

doi:10.1016/j.cpc.2009.06.011

Cited by 18 publications

(18 citation statements)

References 10 publications

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“…The volume distribution is given by v(r) = 4 r 3 3 n(r), so number and volume concentration can be directly calculated from each other. All our examples given will be mono-or multimodal log-normal distributions, defined already in equation (13). We will work with the associated volume distribution accordingly.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…For every error level, example and algorithm, we performed 100 test runs. We always use 21x21 grids for the refractive index, which according to computational experiments (see [13]) is a good compromise between speed and accuracy for the retrieval of the refractive index (on a normal workstation PC, one run needs about 15 minutes to complete). Now, let us take a look at Table 5.…”

Section: Unknown Refractive Indexmentioning

confidence: 99%

“…In this paper, we will focus solely on the retrieval of the volume distribution and refractive index, and the properties derived from it, like the effective radius or the volume concentration; of course, there exist several other problems on the chain from lidar signal data to microphysical properties, like obtaining the extinction and backscatter profiles from the preprocessed signals (see [11,12]), the recognition of homogenous aerosol layers in these profiles, see [6], or the computational complexity of the whole problem (see [13]). The EARLINET measurements started in May 2000 and are still ongoing; up to now, the EARLINET database represents the largest database for the aerosol distribution on a continental scale.…”

Section: Introductionmentioning

confidence: 99%

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An Adaptive Base Point Algorithm for the Retrieval of Aerosol Microphysical Properties

Osterloh

Böckmann²,

Mamouri³

et al. 2011

TOASCJ

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Abstract:We propose a new iterative algorithm for the retrieval of the microphysical properties of stratospheric and tropospheric aerosols from multiwavelength lidar data. We consider the basic equation as an ill-posed problem and solve the system derived from spline collocation via a Padé iteration. The algorithm takes special care of the fact that the reconstruction of the distribution via spline collocation is very sensitive to the choice of base points of the chosen spline basis. The algorithm makes use of this fact by changing the base points used for the spline collocation at certain iteration steps. In addition, the effects of projection to ensure a nonnegative solution are examined. We tested how well this and other algorithms are suitable for retrieving the complex refractive index of the particles as well. We also examine whether the algorithm is capable of distinguishing between different, very small imaginary parts of the refractive index, which is often a main problem in practice. Finally, the algorithm is applied to real multiwavelength Raman lidar data and our results are partially validated by the thermodynamic chemical model Isorropia II.

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Section: Numerical Resultsmentioning

confidence: 99%

Section: Unknown Refractive Indexmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Adaptive Base Point Algorithm for the Retrieval of Aerosol Microphysical Properties

Osterloh

Böckmann²,

Mamouri³

et al. 2011

TOASCJ

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“…the computer runtime of the inversion process is very large. Therefore, we developed a semi-automated software for spherical particles which is able to run on a parallel processor machine (Osterloh et al, 2009) (see Fig. 1).…”

Section: Work At Upmentioning

confidence: 99%

“…The current search algorithm allows for what we describe as embarrassingly parallel processing (i.e. it does not require any interaction between the workers and therefore scales to a large number of workers (Osterloh et al, 2009).…”

Section: Up Algorithm 221 Solving the Fredholm Equations And Descrimentioning

confidence: 99%

Microphysical particle properties derived from inversion algorithms developed in the framework of EARLINET

et al. 2016

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Abstract. We present a summary on the current status of two inversion algorithms that are used in EARLINET (European Aerosol Research Lidar Network) for the inversion of data collected with EARLINET multiwavelength Raman lidars. These instruments measure backscatter coefficients at 355, 532, and 1064 nm, and extinction coefficients at 355 and 532 nm. Development of these two algorithms started in 2000 when EARLINET was founded. The algorithms are based on a manually controlled inversion of optical data which allows for detailed sensitivity studies. The algorithms allow us to derive particle effective radius as well as volume and surface area concentration with comparably high confidence. The retrieval of the real and imaginary parts of the complex refractive index still is a challenge in view of the accuracy required for these parameters in climate change studies in which light absorption needs to be known with high accuracy. It is an extreme challenge to retrieve the real part with an accuracy better than 0.05 and the imaginary part with accuracy better than 0.005-0.1 or ±50 %. Single-scattering albedo can be computed from the retrieved microphysical parameters and allows us to categorize aerosols into high-and low-absorbing aerosols.On the basis of a few exemplary simulations with synthetic optical data we discuss the current status of these manually operated algorithms, the potentially achievable accuracy of data products, and the goals for future work. One algorithm was used with the purpose of testing how well microphysical parameters can be derived if the real part of the complex refractive index is known to at least 0.05 or 0.1. The other algorithm was used to find out how well microphysical parameters can be derived if this constraint for the real part is not applied.The optical data used in our study cover a range of Ångström exponents and extinction-to-backscatter (lidar) ratios that are found from lidar measurements of various aerosol types. We also tested aerosol scenarios that are considered highly unlikely, e.g. the lidar ratios fall outside the commonly accepted range of values measured with Raman lidar, even though the underlying microphysical particle properties are not uncommon. The goal of this part of the study is to test the robustness of the algorithms towards their ability to identify aerosol types that have not been measured so far, but cannot be ruled out based on our current knowledge of aerosol physics.We computed the optical data from monomodal logarithmic particle size distributions, i.e. we explicitly excluded the more complicated case of bimodal particle size distributions which is a topic of ongoing research work. Another constraint is that we only considered particles of spherical shape in our simulations. We considered particle radii as large asPublished by Copernicus Publications on behalf of the European Geosciences Union. D. Müller et al.: EARLINET inversion algorithms7-10 µm in our simulations where the Potsdam algorithm is limited to the lower value. We considered optical-d...

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Remote sensing and in-situ measurements of tropospheric aerosol, a PAMARCMiP case study

Hoffmann

Osterloh

Stone

et al. 2012

Atmospheric Environment

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a b s t r a c tIn this work, a closure experiment for tropospheric aerosol is presented. Aerosol size distributions and single scattering albedo from remote sensing data are compared to those measured in-situ. An aerosol pollution event on 4 April 2009 was observed by ground based and airborne lidar and photometer in and around Ny-Ålesund, Spitsbergen, as well as by DMPS, nephelometer and particle soot absorption photometer at the nearby Zeppelin Mountain Research Station.The presented measurements were conducted in an area of 40 Â 20 km around Ny-Ålesund as part of the 2009 Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project (PAMARCMiP). Aerosol mainly in the accumulation mode was found in the lower troposphere, however, enhanced backscattering was observed up to the tropopause altitude. A comparison of meteorological data available at different locations reveals a stable multi-layer-structure of the lower troposphere. It is followed by the retrieval of optical and microphysical aerosol parameters. Extinction values have been derived using two different methods, and it was found that extinction (especially in the UV) derived from Raman lidar data significantly surpasses the extinction derived from photometer AOD profiles. Airborne lidar data shows volume depolarization values to be less than 2.5% between 500 m and 2.5 km altitude, hence, particles in this range can be assumed to be of spherical shape. In-situ particle number concentrations measured at the Zeppelin Mountain Research Station at 474 m altitude peak at about 0.18 mm diameter, which was also found for the microphysical inversion calculations performed at 850 m and 1500 m altitude. Number concentrations depend on the assumed extinction values, and slightly decrease with altitude as well as the effective particle diameter. A low imaginary part in the derived refractive index suggests weakly absorbing aerosols, which is confirmed by low black carbon concentrations, measured at the Zeppelin Mountain as well as on board the Polar 5 aircraft.

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Parallel software for retrieval of aerosol distribution from LIDAR data in the framework of EARLINET-ASOS

Cited by 18 publications

References 10 publications

An Adaptive Base Point Algorithm for the Retrieval of Aerosol Microphysical Properties

An Adaptive Base Point Algorithm for the Retrieval of Aerosol Microphysical Properties

Microphysical particle properties derived from inversion algorithms developed in the framework of EARLINET

Remote sensing and in-situ measurements of tropospheric aerosol, a PAMARCMiP case study

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