Technical note: Absorption aerosol optical depth components from AERONET observations of mixed dust plumes

© Author(s) 2019.Absorption aerosol optical depth (AAOD) as obtained from sun–sky photometer measurements provides a measure of the light-absorbing properties of the columnar aerosol loading. However, it is not an unambiguous aerosol-type-specific parameter, particularly if several types of absorbing aerosols, for instance black carbon (BC) and mineral dust, are present in a mixed aerosol plume. The contribution of mineral dust to total aerosol light absorption is particularly important at UV wavelengths. In this study we refine a lidar-based technique applied to the separation of dust and non-dust aerosol types for the use with Aerosol Robotic Network (AERONET) direct sun and inversion products. We extend the methodology to retrieve AAOD related to non-dust aerosol (AAODnd) and BC (AAODBC). We test the method at selected AERONET sites that are frequently affected by aerosol plumes that contain a mixture of Saharan or Asian mineral dust and biomass-burning smoke or anthropogenic pollution, respectively. We find that aerosol optical depth (AOD) related to mineral dust as obtained with our methodology is frequently smaller than coarse-mode AOD. This suggests that the latter is not an ideal proxy for estimating the contribution of mineral dust to mixed dust plumes. We present the results of the AAODBC retrieval for the selected AERONET sites and compare them to coincident values provided in the Copernicus Atmosphere Monitoring System aerosol reanalysis.We find that modelled and AERONET AAODBC are most consistent for Asian sites or at Saharan sites with strong local anthropogenic sources.Peer reviewe

A vingança da mímesis: historicidade e midiatização da cultura na narrativa seriada televisiva

The serial televised fiction takes place in a situation in which the empirical reality interacts with the fictional creation. History is recounted through criteria, which are dictated by the principles, which govern the construction of the televised show. The flowing of this narrative undergoes a course of two-way course: the facts, which mark the daily action of the media and regulate fiction and vice-versa. Thus, the soap opera becomes the object of informal conversations, proposing a wide debate, which goes beyond the conventional spheres of the fictional narrative, bringing to the common citizen elements to judge issues of interest to the polis. This article discusses this specific way in which media and public interact, mapping some essential elements to understand the most comprising questions, which mark the interaction between the televised media and culture. Keywords: telenovela, television, narrativity.A ficção seriada televisiva constitui-se num espaço em que a realidade empírica interage com a criação ficcional. Ali, a História é recontada a partir de critérios ditados pelos princípios que regem as práticas de construção do espetáculo televisivo. O fluxo dessa narrativa percorre um caminho de duas mãos: os fatos que marcam o cotidiano da mídia pautam a ficção e vice-versa. Assim, a telenovela torna-se objeto das conversas informais, propondo um amplo debate que ultrapassa as esferas convencionais da narrativa ficcional, fornecendo ao cidadão comum elementos para opinar sobre questões de interesse da polis. O presente artigo discute esse modo específico de interação da mídia com o público, mapeando alguns elementos essenciais para a compreensão de questões mais abrangentes que marcam a interação da mídia televisiva com a cultura. Palavras-chaves: telenovela, televisão, narratividade

A vingança da mímesis: historicidade e midiatização da cultura na narrativa seriada televisiva

The serial televised fiction takes place in a situation in which the empirical reality interacts with the fictional creation. History is recounted through criteria, which are dictated by the principles, which govern the construction of the televised show. The flowing of this narrative undergoes a course of two-way course: the facts, which mark the daily action of the media and regulate fiction and vice-versa. Thus, the soap opera becomes the object of informal conversations, proposing a wide debate, which goes beyond the conventional spheres of the fictional narrative, bringing to the common citizen elements to judge issues of interest to the polis. This article discusses this specific way in which media and public interact, mapping some essential elements to understand the most comprising questions, which mark the interaction between the televised media and culture. Keywords: telenovela, television, narrativity.A ficção seriada televisiva constitui-se num espaço em que a realidade empírica interage com a criação ficcional. Ali, a História é recontada a partir de critérios ditados pelos princípios que regem as práticas de construção do espetáculo televisivo. O fluxo dessa narrativa percorre um caminho de duas mãos: os fatos que marcam o cotidiano da mídia pautam a ficção e vice-versa. Assim, a telenovela torna-se objeto das conversas informais, propondo um amplo debate que ultrapassa as esferas convencionais da narrativa ficcional, fornecendo ao cidadão comum elementos para opinar sobre questões de interesse da polis. O presente artigo discute esse modo específico de interação da mídia com o público, mapeando alguns elementos essenciais para a compreensão de questões mais abrangentes que marcam a interação da mídia televisiva com a cultura. Palavras-chaves: telenovela, televisão, narratividade

Seasonal variation of aerosol water uptake and its impact on the direct radiative effect at Ny-Ålesund, Svalbard

© Author(s) 2014. This work is distributed under the Creative Commons Attribution 3.0 LicenseIn this study we investigated the impact of water uptake by aerosol particles in ambient atmosphere on their optical properties and their direct radiative effect (ADRE, W m-2) in the Arctic at Ny-Ålesund, Svalbard, during 2008. To achieve this, we combined three models, a hygroscopic growth model, a Mie model and a radiative transfer model, with an extensive set of observational data. We found that the seasonal variation of dry aerosol scattering coefficients showed minimum values during the summer season and the beginning of fall (July-August-September), when small particles (< 100 nm in diameter) dominate the aerosol number size distribution. The maximum scattering by dry particles was observed during the Arctic haze period (March-April-May) when the average size of the particles was larger. Considering the hygroscopic growth of aerosol particles in the ambient atmosphere had a significant impact on the aerosol scattering coefficients: the aerosol scattering coefficients were enhanced by on average a factor of 4.30 ± 2.26 (mean ± standard deviation), with lower values during the haze period (March-April-May) as compared to summer and fall. Hygroscopic growth of aerosol particles was found to cause 1.6 to 3.7 times more negative ADRE at the surface, with the smallest effect during the haze period (March-April-May) and the highest during late summer and beginning of fall (July-August-September).Peer reviewe

Are violations to temporal Bell inequalities there when somebody looks?

The possibility of observing violations of temporal Bell inequalities, originally proposed by Leggett as a mean of testing the quantum mechanical delocalization of suitably chosen macroscopic bodies, is discussed by taking into account the effect of the measurement process. A general criterion quantifying this possibility is defined and shown not to be fulfilled by the various experimental configurations proposed so far to test inequalities of different forms.Comment: 7 pages, 1 eps figure, needs europhys.sty and euromacr.tex, enclosed in the .tar.gz file; accepted for publication in Europhysics Letter

Modeling and Simulation of a Microstrip-SQUID Amplifier

Using a simple lumped-circuit model, we numerically study the dependence of the voltage gain and noise on the amplifier's parameters. Linear, quasi-linear, and nonlinear regimes are studied. We have shown that the voltage gain of the amplifier cannot exceed a characteristic critical value, which decreases with the increase of the input power. We have also shown that the spectrum of the voltage gain depends significantly on the level of the Johnson noise generated by the SQUID resistors.Comment: 13 page

A first global height-resolved cloud condensation nuclei data set derived from spaceborne lidar measurements

We present a global multiyear height-resolved data set of aerosol-type-specific cloud condensation nuclei concentrations (nCCN) estimated from the spaceborne lidar aboard the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. For estimating nCCN, we apply the recently introduced Optical Modelling of the CALIPSO Aerosol Microphysics (OMCAM) algorithm to the CALIPSO Level 2 Aerosol Profile product. The estimated nCCN are then gridded into a uniform latitude–longitude grid of 2∘×5∘, a vertical grid of resolution 60 m from the surface to an altitude of 8 km, and a temporal resolution of 1 month. The data span a total of 186 months, from June 2006 to December 2021. In addition, we provide a 3D aerosol-type-specific climatology of nCCN produced using the complete time series. We further highlight some potential applications of the data set in the context of aerosol–cloud interactions. The complete data set can be accessed at https://doi.org/10.1594/PANGAEA.956215 (Choudhury and Tesche, 2023).</p

Optimal Monitoring of Position in Nonlinear Quantum Systems

We discuss a model of repeated measurements of position in a quantum system which is monitored for a finite amount of time with a finite instrumental error. In this framework we recover the optimum monitoring of a harmonic oscillator proposed in the case of an instantaneous collapse of the wavefunction into an infinite-accuracy measurement result. We also establish numerically the existence of an optimal measurement strategy in the case of a nonlinear system. This optimal strategy is completely defined by the spectral properties of the nonlinear system.Comment: 4 pages, REVTeX 3.0, 4 PostScript figure

Numerical simulations of optical properties of Saharan dust aerosols with emphasis on lidar applications

In the framework of the Saharan Mineral Dust Experiment (SAMUM) for the first time the spectral dependence of particle linear depolarization ratios was measured by combining four lidar systems. In this paper these measurements are compared with results from scattering theory based on the T-matrix method. For this purpose, in situ measurements—size distribution, shape distribution and refractive index—were used as input parameters; particle shape was approximated by spheroids. A sensitivity study showed that lidar-related parameters—lidar ratio Sp and linear depolarization ratio δp—are very sensitive to changes of all parameters. The simulated values of the δp are in the range of 20% and 31% and thus in the range of the measurements. The spectral dependence is weak, so that it could not be resolved by the measurements. Calculated lidar ratios based on the measured microphysics and considering equivalent radii up to 7.5μm show a range of possible values between 29 and 50 sr at λ = 532 nm. Larger Sp might be possible if the real part of the refractive index is small and the imaginary part is large. A strict validation was however not possible as too many microphysical parameters influence Sp and δp that could not be measured with the required accuracy

Microphysical and optical properties of dust and tropical biomass burning aerosol layers in the Cape Verde region – An overview of the airborne in-situ and lidar measurements during SAMUM-2

In the framework of the Saharan Mineral Dust Experiment (SAMUM) airborne High Spectral Resolution Lidar and in situ measurements of the particle size, aerosol mixing state and absorption coefficient were conducted. Here, the properties of mineral dust and tropical biomass burning layers in the Cape Verde region in January/February 2008 are investigated and compared with the properties of fresh dust observed in May/June 2006 close the Sahara. In the Cape Verde area, we found a complex stratification with dust layers covering the altitude range below 2 km and biomass burning layers aloft. The aerosol type of the individual layers was classified based on depolarization and lidar ratios and, in addition, on in situ measured Ångström exponents of absorption °aap. The dust layers had a depth of 1.3 ± 0.4 km and showed a median °aap of 3.95. The median effective diameter Deff was 2.5 μm and the dust layers over Cape Verde yielded clear signals of aging: large particles were depleted due to gravitational settling and the accumulation mode diameter was shifted towards larger sizes as a result of coagulation. The tropical biomass layers had a depth of 2.0 ± 1.1 km and were characterized by a median °aap of 1.34. They always contained a certain amount of large dust particles and showed a median Deff of 1.1 μm and a fine mode Deff,fine of 0.33. The dust and biomass burning layers had a median aerosol optical depth (AOD) of 0.23 and 0.09, respectively. The median contributions to the AOD of the total atmospheric column below 10 km were 75 and 37%, respectively