Automated, unsupervised inversion of multiwavelength lidar data with TiARA : Assessment of retrieval performance of microphysical parameters using simulated data

We evaluate the retrieval performance of the automated, unsupervised inversion algorithm, Tikhonov Advanced Regularization Algorithm (TiARA), which is used for the autonomous retrieval of microphysical parameters of anthropogenic and natural pollution particles. TiARA (version 1.0) has been developed in the past 10 years and builds on the legacy of a data-operator-controlled inversion algorithm used since 1998 for the analysis of data from multiwavelength Raman lidar. The development of TiARA has been driven by the need to analyze in (near) real time large volumes of data collected with NASA Langley Research Center's high-spectral-resolution lidar (HSRL-2). HSRL-2 was envisioned as part of the NASA Aerosols-Clouds-Ecosystems mission in response to the National Academy of Sciences (NAS) Decadal Study mission recommendations 2007. TiARA could thus also serve as an inversion algorithm in the context of a future space-borne lidar. We summarize key properties of TiARA on the basis of simulations with monomodal logarithmic-normal particle size distributions that cover particle radii from approximately 0.05 μm to 10 μm. The real and imaginary parts of the complex refractive index cover the range from nonabsorbing to highly light-absorbing pollutants. Our simulations include up to 25% measurement uncertainty. The goal of our study is to provide guidance with respect to technical features of future space-borne lidars, if such lidars will be used for retrievals of microphysical data products, absorption coefficients, and single-scattering albedo. We investigate the impact of two different measurement-error models on the quality of the data products.We also obtain for the first time, to the best of our knowledge, a statistical view on systematic and statistical uncertainties, if a large volume of data is processed. Effective radius is retrieved to 50% accuracy for 58% of cases with an imaginary part up to 0.01i and up to 100% of cases with an imaginary part of 0.05i. Similarly, volume concentration, surface-area concentration, and number concentrations are retrieved to 50% accuracy in 56%-100% of cases, 99%-100% of cases, and 54%-87% of cases, respectively, depending on the imaginary part. The numbers represent measurement uncertainties of up to 15%. If we target 20% retrieval accuracy, the numbers of cases that fall within that threshold are 36%-76% for effective radius, 36%-73% for volume concentration, 98%-100% for surface-area concentration, and 37%-61% for number concentration. That range of numbers again represents a spread in results for different values of the imaginary part. At present, we obtain an accuracy of (on average) 0.1 for the real part. A case study from the ORCALES field campaign is used to illustrate data products obtained with TiARA.Peer reviewe

Retrieval of aerosol parameters from multiwavelength lidar : Investigation of underlying inverse mathematical problem

This is the accepted version of the following article: Eduard Chemyakin, Sharon Burton, Alexei Kolgotin, Detlef Muller, Chris Hostetler, and Richard Ferrare, ‘Retrieval of aerosol parameters from multiwavelength lidar: investigation of the underlying inverse mathematical problem’, Applied Optics Vol 55(9): 2188-2202 (2016). Under embargo. Embargo end date: 16 March 2017. The final, published version is available online via doi: https://doi.org/10.1354/AO.55.002188 © 2016 Optical Society of America.We present an investigation of some important mathematical and numerical features related to the retrieval of microphysical parameters (complex refractive index, single-scattering albedo, effective radius, total number, surface area, and volume concentrations) of ambient aerosol particles using multiwavelength Raman or high-spectral-resolution lidar. Using simple examples we prove the non-uniqueness of an inverse solution to be the major source of the retrieval difficulties. Some theoretically possible ways of partially compensating for these difficulties are offered. For instance, an increase in the variety of input data via combination of lidar and certain passive remote sensing instruments will be helpful to reduce the error of estimation of complex refractive index. Also we demonstrate significant interference between Aitken and accumulation aerosol modes in our inversion algorithm and confirm that the solutions can be better constrained by limiting the particle radii. Applying a combination of analytical approach and numerical simulations, we explain statistical behavior of the microphysical size parameters. We reveal and clarify why the total surface area concentration is consistent even in the presence of non-unique solution sets and is on average the most stable parameter to be estimated, as long as at least one extinction optical coefficient is employed. We find that for a selected particle size distributions the total surface area and volume concentrations can be quickly retrieved with fair precision using only a single extinction coefficients in a simple arithmetical relationship.Peer reviewedFinal Accepted Versio

Improved identification of the solution space of aerosol microphysical properties derived from the inversion of profiles of lidar optical data, part 3: Case studies

This is an Open Access article published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License https://creativecommons.org/licenses/by/4.0/. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.We conclude our series of publications on the development of the gradient correlation method (GCM) which can be used for an improved stabilization of the solution space of particle microphysical parameters derived from measurements with multiwavelength Raman and High‐Spectral‐Resolution Lidar (3 backscatter + 2 extinction coefficients). We show results of three cases studies. The data were taken with a ground‐based multiwavelength Raman lidar during the Saharan Mineral Dust Experiment (SAMUM) in the Cape Verde Islands (North Atlantic). These cases describe mixtures of dust with smoke. For our data analysis we separated the contribution of smoke to the total signal and only used these optical profiles for the test of GCM. The results show a significant stabilization of the solution space of the particle microphysical parameter retrieval on the particle radius domain from 0.03 μm to 10 μm, the real part of the complex refractive index domain from 1.3 to 1.8 and the imaginary part from 0 to 0.1. This new method will be included in TiARA (Tikhonov Advanced Regularization Algorithm) which is a fully automated, unsupervised algorithm that is used for the analysis of the world‐wide first airborne 3 backscatter + 2 extinction high‐spectral‐resolution lidar developed by NASA Langley Research Center.Peer reviewe

A new method to retrieve the real part of the equivalent refractive index of atmospheric aerosols

This document is the Accepted Manuscript version of the following article: S. Vratolis, et al, ‘A new method to retrieve the real part of the equivalent refractive index of atmospheric aerosols’, Journal of Aerosol Science, Vol. 117: 54-62, March 2018. Under embargo until 29 December 2019. The final, published version is available online at DOI: https://doi.org/10.1016/j.jaerosci.2017.12.013.In the context of the international experimental campaign Hygroscopic Aerosols to Cloud Droplets (HygrA-CD, 15 May to 22 June 2014), dry aerosol size distributions were measured at Demokritos station (DEM) using a Scanning Mobility Particle Sizer (SMPS) in the size range from 10 to 550 nm (electrical mobility diameter), and an Optical Particle Counter (OPC model Grimm 107 operating at the laser wavelength of 660 nm) to acquire the particle size distribution in the size range of 250 nm to 2.5 μm optical diameter. This work describes a method that was developed to align size distributions in the overlapping range of the SMPS and the OPC, thus allowing us to retrieve the real part of the aerosol equivalent refractive index (ERI). The objective is to show that size distribution data acquired at in situ measurement stations can provide an insight to the physical and chemical properties of aerosol particles, leading to better understanding of aerosol impact on human health and earth radiative balance. The resulting ERI could be used in radiative transfer models to assess aerosol forcing direct effect, as well as an index of aerosol chemical composition. To validate the method, a series of calibration experiments were performed using compounds with known refractive index (RI). This led to a corrected version of the ERI values, (ERICOR). The ERICOR values were subsequently compared to model estimates of RI values, based on measured PM2.5 chemical composition, and to aerosol RI retrieved values by inverted lidar measurements on selected days.Peer reviewe

1064 nm rotational Raman lidar for particle extinction and lidar-ratio profiling: cirrus case study

For the first time, vertical profiles of the 1064 nm particle extinction coefficient obtained from Raman lidar observations at 1058 nm (nitrogen and oxygen rotational Raman backscatter) are presented. We applied the new technique in the framework of test measurements and performed several cirrus observations of particle backscatter and extinction coefficients, and corresponding extinction-to-backscatter ratios at the wavelengths of 355, 532, and 1064 nm. The cirrus backscatter coefficients were found to be equal for all three wavelengths keeping the retrieval uncertainties in mind. The multiple-scattering-corrected cirrus extinction coefficients at 355 nm were on average about 20–30 % lower than the ones for 532 and 1064 nm. The cirrus-mean extinction-to-backscatter ratio (lidar ratio) was 31 ± 5 sr (355 nm), 36 ± 5 sr (532 nm), and 38 ± 5 sr (1064 nm) in this single study. We further discussed the requirements needed to obtain aerosol extinction profiles in the lower troposphere at 1064 nm with good accuracy (20 % relative uncertainty) and appropriate temporal and vertical resolution

Depolarization and lidar ratios at 355, 532, and 1064 nm and microphysical properties of aged tropospheric and stratospheric Canadian wildfire smoke

We present spectrally resolved optical and microphysical properties of western Canadian wildfire smoke observed in a tropospheric layer from 5-6.5 km height and in a stratospheric layer from 15-16 km height during a recordbreaking smoke event on 22 August 2017. Three polarization/ Raman lidars were run at the European Aerosol Research Lidar Network (EARLINET) station of Leipzig, Germany, after sunset on 22 August. For the first time, the linear depolarization ratio and extinction-to-backscatter ratio (lidar ratio) of aged smoke particles were measured at all three important lidar wavelengths of 355, 532, and 1064 nm. Very different particle depolarization ratios were found in the troposphere and in the stratosphere. The obviously compact and spherical tropospheric smoke particles caused almost no depolarization of backscattered laser radiation at all three wavelengths ( 500nm). The stratospheric smoke particles formed a pronounced accumulation mode (in terms of particle volume or mass) centered at a particle radius of 350-400 nm. The effective particle radius was 0.32 μm. The tropospheric smoke particles were much smaller (effective radius of 0.17 μm). Mass concentrations were of the order of 5.5 μgm-3 (tropospheric layer) and 40 μgm-3 (stratospheric layer) in the night of 22 August 2017. The single scattering albedo of the stratospheric particles was estimated to be 0.74, 0.8, and 0.83 at 355, 532, and 1064 nm, respectively

Measurements of Aerosol Size and Microphysical Properties: A Comparison Between Raman Lidar and Airborne Sensors

This manuscript compares measurements of aerosol size distributions and microphysical properties retrieved from the Raman lidar BASIL with those obtained from a series of aircraft sensors during HyMeX-SOP1. The attention is focused on a measurement session on 02 October 2012, with BASIL measurements revealing the presence of a lower aerosol layer extending up to 3.3 km and an elevated layer extending from 3.6 to 4.6 km. Aerosol size distribution and microphysical properties are determined from multi-wavelength particle backscattering and extinction profile measurements through a retrieval approach based on Tikhonov regularization. A good agreement is found between BASIL and the microphysical sensors' measurements for all considered aerosol size and microphysical properties. Specifically, BASIL and in-situ volume concentration values are in the range 2-5 mu m(3) cm(-3) in the lower layer and in the range 1-3.5 mu m(3) cm(-3) in the upper layer. Values of the effective radius values from BASIL and the in-situ sensors are in the range 0.2-0.6 mu m in both the lower and upper layer. Aerosol size distributions are determined at 2.2, 2.8, 4 and 4.3 km, with a good agreement between the Raman lidar and the microphysical sensors at all considered heights. We combined these size and microphysical results with Lagrangian back-trajectory analyses and chemical composition measurements. From this combination of datasets we conclude that aerosol particles below 3 km were probably originated by wildfires in North America and/or by anthropogenic activities in North-Eastern Europe, while aerosols above 3 km were also probably originated by wildfires in North America

ГОСУДАРСТВЕННО-ЧАСТНОЕ ПАРТНЕРСТВО В ИННОВАЦИОННОЙ СФЕРЕ: СОВРЕМЕННОЕ СОСТОЯНИЕ И ПЕРСПЕКТИВЫ

In article the current state is analyzed is state-private partnership, the problems constraining its further development, among which imperfection of legislative and standard and legal base, a fi scal orientation of the tax law, lack of mechanisms of long-term fi nancing, low level of trust of business to the government, the high level of corruption, etc. are revealed. It is off ered to introduce amendments in partnership mechanisms the including creations of the favorable economic and standard and legal environment, formation at businessmen of motivation to development of innovative activity, development of new organizational mechanisms of system of public-private partnership, strengthening of state support of commercialization of results of scientifi c activity, etc. The purpose of article is increase of effi ciency of public-private partnership in the innovative sphere.Article tasks: to investigate the main reasons constraining development of public-private partnership in the innovative sphere to off er measures for their elimination really to promote increase of the mechanism of public-private partnership.Methodology. Process, system, integration and functional approaches are the basis for methodical development.Results. The main forms of public-private partnership used in the Russian practice are analysed. The rating of regions of the Russian Federation on public-private partnership development is given. The main reasons infl uencing further development of public-private partnership in modern economic conditions are analysed. The measures of legislative and institutional orders urged to increase efficiency of this mechanism in the conditions of transition to innovative economy are off ered.Conclusions / importance. Expansion of use of the mechanism of public-private partnership will allow Russia to answer modern technological calls surely. However it can be reached only due to ensuring due level of economic freedom, creation of equal conditions of competitiveness, rule of law, and also eff ective integration of the power, science, education and business.В статье анализируется современное состояние государственно-частного партнерства, выявлены проблемы, сдерживающие его дальнейшее развитие, среди которых несовершенство законодательной и нормативно-правовой базы, фискальная направленность налогового законодательства, отсутствие механизмов долгосрочного финансирования, низкий уровень доверия бизнеса к государственной власти, высокий уровень коррупции и др. Предложено внести коррективы в механизмы партнерства включающие создание благоприятной экономической и нормативно-правовой среды, формирование у предпринимателей мотивации к развитию инновационной деятельности, разработку новых организационных механизмов системы государственно-частного партнерства, усиление господдержки коммерциализации результатов научной деятельности и др.Целью статьи является повышение эффективности государственно-частного партнерства в инновационной сфере. Задачи статьи: исследовать основные причины, сдерживающие развитие государственно-частного партнерства в инновационной сфере, предложить меры по их устранению с тем, чтобы реально способствовать повышению механизма государственно-частного партнерства.Методология. В основу методических разработок положены процессный, системный, интеграционный и функциональный подходы.Результаты. Проанализированы основные формы государственно-частного партнерства, используемые в российской практике. Приведен рейтинг регионов РФ по развитию государственно-частного партнерства. Проанализированы основные причины, влияющие на дальнейшее развитие государственно-частного партнерства в современных экономических условиях. Предложены меры законодательного и институционального порядков, призванные повысить эффективность этого механизма в условиях перехода к инновационной экономике.Выводы / значимость. Расширение использования механизма государственно-частного партнерства позволят России уверенно ответить на современные технологические вызовы. Однако это может быть достигнуто лишь за счет обеспечения должного уровня экономической свободы, создания равных условий конкурентоспособности, верховенства закона, а также эффективной интеграции власти, науки, образования и бизнеса

Effects of systematic and random errors on the retrieval of particle microphysical properties from multiwavelength lidar measurements using inversion with regularization

In this work we study the effects of systematic and random errors on the inversion of multiwavelength (MW) lidar data using the well-known regularization technique to obtain vertically resolved aerosol microphysical properties. The software implementation used here was developed at the Physics Instrumentation Center (PIC) in Troitsk (Russia) in conjunction with the NASA/Goddard Space Flight Center. Its applicability to Raman lidar systems based on backscattering measurements at three wavelengths (355, 532 and 1064 nm) and extinction measurements at two wavelengths (355 and 532 nm) has been demonstrated widely. The systematic error sensitivity is quantified by first determining the retrieved parameters for a given set of optical input data consistent with three different sets of aerosol physical parameters. Then each optical input is perturbed by varying amounts and the inversion is repeated. Using bimodal aerosol size distributions, we find a generally linear dependence of the retrieved errors in the microphysical properties on the induced systematic errors in the optical data. For the retrievals of effective radius, number/surface/volume concentrations and fine-mode radius and volume, we find that these results are not significantly affected by the range of the constraints used in inversions. But significant sensitivity was found to the allowed range of the imaginary part of the particle refractive index. Our results also indicate that there exists an additive property for the deviations induced by the biases present in the individual optical data. This property permits the results here to be used to predict deviations in retrieved parameters when multiple input optical data are biased simultaneously as well as to study the influence of random errors on the retrievals. The above results are applied to questions regarding lidar design, in particular for the spaceborne multiwavelength lidar under consideration for the upcoming ACE mission.This work was supported by the NASA/Goddard Space Flight Center, the Spanish Ministry of Science and Technology through projects CGL2010-18782 and CSD2007-00067, the Andalusian Regional Government through projects P10-RNM-6299 and P08-RNM-3568, the EU through ACTRIS project (EU INFRA-2010-1.1.16-262254) and the Postdoctoral Program of the University of Granada