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

Assessing lidar-based classification schemes for polar stratospheric clouds based on 16 years of measurements at Esrange, Sweden

This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License CC BY-NC-ND 3.0 https://creativecommons.org/licenses/by-nc-nd/3.0/, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.Lidar measurements of polar stratospheric clouds (PSCs) are commonly analyzed in classification schemes that apply the backscatter ratio and the particle depolarization ratio. This similarity of input data suggests comparable results of different classification schemes - despite measurements being performed with a variety of mostly custom-made instruments. Based on a time series of 16 years of lidar measurements at Esrange (68°N, 21°E), Sweden, we show that PSC classification differs substantially depending on the applied scheme. The discrepancies result from varying threshold values of lidar-derived parameters used to define certain PSC types. The resulting inconsistencies could impact the understanding of long-term PSC observations documented in the literature. We identify two out of seven considered classification schemes that are most likely to give reliable results and should be used in future lidar-based studies. Using polarized backscatter ratios gives the advantage of increased contrast for observations of weakly backscattering and weakly depolarizing particles. Improved confidence in PSC classification can be achieved by a more comprehensive consideration of the effect of measurement uncertainties. The particle depolarization ratio is the key to a reliable identification of different PSC types. Hence, detailed information on the calibration of the polarization-sensitive measurement channels should be provided to assess the findings of a study. Presently, most PSC measurements with lidar are performed at 532 nm only. The information from additional polarization-sensitive measurements in the near infrared could lead to an improved PSC classification. Coincident lidar-based temperature measurements at PSC level might provide useful information for an assessment of PSC classification. Key Points Assessment of PSC classification schemes Statistical analysis of PSC observations Recommendations for lidar-based PSC studiesPeer reviewe

Tax Harmonization or Competition?: Croatia and Neighboring Countries

Tax systems vary widely among countries, or in the cases of the US or Germany, among lower levels of government as well. There is some consensus that taxes among neighboring countries should be harmonized, or at least that the rates should be fairly close, to prevent distortions in trade. On the other hand, tax competition in the form of various tax concessions to attract new businesses is also common. In the US, a number of States have come to agreements to harmonize rates or otherwise cooperate, but more do not make any attempt to deal with the effects of differing rates. The EU is currently discussing harmonization of direct taxes while indirect tax rates still vary widely. Countries and lower levels of governments do not willingly give up their right to set tax rates, regardless of the possible effects on trade. This paper will briefly consider the recent history of tax harmonization and competition in the US and Europe. This will be followed by an examination of the current situation in Croatia and neighboring countries. The scope for competition and/or need for harmonization will be explored. Comparison tables of taxes and rates in the US, EU, Croatia, Slovenia, Hungary, Yugoslavia and BiH will be included.

Assessment of two aerosol optical thickness retrieval algorithms applied to MODIS aqua and terra measurements in Europe

© Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 LicenseThe aim of the present study is to validate AOT (aerosol optical thickness) and A° ngström exponent (α), obtained from MODIS (MODerate resolution Imaging Spectroradiometer) Aqua and Terra calibrated level 1 data (1 km horizontal resolution at ground) with the SAER (Satellite AErosol Retrieval) algorithm and with MODIS Collection 5 (c005) standard product retrievals (10 km horizontal resolution), against AERONET (AErosol RObotic NETwork) sun photometer observations over land surfaces in Europe. An inter-comparison of AOT at 0.469 nm obtained with the two algorithms has also been performed. The time periods investigated were chosen to enable a validation of the findings of the two algorithms for a maximal possible variation in sun elevation. The satellite retrievals were also performed with a significant variation in the satellite-viewing geometry, since Aqua and Terra passed the investigation area twice a day for several of the cases analyzed. The validation with AERONET shows that the AOT at 0.469 and 0.555 nm obtained with MODIS c005 is within the expected uncertainty of one standard deviation of the MODIS c005 retrievals (1AOT =±0.05±0.15 ·AOT). The AOT at 0.443 nm retrieved with SAER, but with a much finer spatial resolution, also agreed reasonably well with AERONET measurements. The majority of the SAER AOT values are within the MODIS c005 expected uncertainty range, although somewhat larger average absolute deviation occurs compared to the results obtained with the MODIS c005 algorithm. The discrepancy between AOT from SAER and AERONET is, however, substantially larger for the wavelength 488 nm. This means that the values are, to a larger extent, outside of the expected MODIS uncertainty range. In addition, both satellite retrieval algorithms are unable to estimate accurately, although the MODIS c005 algorithm performs better. Based on the inter-comparison of the SAER and MODIS c005 algorithms, it was found that SAER on the whole is able to obtain results within the expected uncertainty range of MODIS Aqua and Terra observations.Peer reviewe

Versions of political history trauma in the Rodrigo Lira poetry

Indexación: Scopus.Este artículo tiene por objetivo realizar una nueva propuesta de análisis de la poesía de Rodrigo Lira (1949-1981) que desde la textualidad articula la dimensión histórico-política y la experiencia del trauma en un momento específico de la sociedad chilena, a saber, post golpe militar. Desde un enfoque interdisciplinario, que considera el aporte de los estudios culturales y el psicoanálisis, se sostiene que en la poesía del autor las versiones del trauma histórico político entendidas como tensiones discursivas, corresponden a un proceso de propuesta/resistencia discursiva e ideológica. El corpus utilizado corresponde a poemas seleccionados del texto Proyecto de obras completas (2013).This article aims to make a new proposal for the analysis of the poetry of Rodrigo Lira (1949-1981) from the textuality articulates the historical-political dimension and the «trauma» cultural experience at a specific moment of chilean society, namely, post military coup. From an interdisciplinary approach that considers the contribution of cultural studies and psychoanalysis, the hypothesis holds that in the poetry of the author's versions of political historical trauma understood as discursive tensions correspond to a process of proposal / discursive and ideological resistance. The corpus used correspond to select poems form the text Proyecto de obras completas (2013).http://ref.scielo.org/39zjr

Tax Harmonization or Competition?: Croatia and Neighboring Countries

Tax systems vary widely among countries, or in the cases of the US or Germany, among lower levels of government as well. There is some consensus that taxes among neighboring countries should be harmonized, or at least that the rates should be fairly close, to prevent distortions in trade. On the other hand, tax competition in the form of various tax concessions to attract new businesses is also common. In the US, a number of States have come to agreements to harmonize rates or otherwise cooperate, but more do not make any attempt to deal with the effects of differing rates. The EU is currently discussing harmonization of direct taxes while indirect tax rates still vary widely. Countries and lower levels of governments do not willingly give up their right to set tax rates, regardless of the possible effects on trade. This paper will briefly consider the recent history of tax harmonization and competition in the US and Europe. This will be followed by an examination of the current situation in Croatia and neighboring countries. The scope for competition and/or need for harmonization will be explored. Comparison tables of taxes and rates in the US, EU, Croatia, Slovenia, Hungary, Yugoslavia and BiH will be included

Testing temporal Bell inequalities through repeated measurements in rf-SQUIDs

Temporal Bell-like inequalities are derived taking into account the influence of the measurement apparatus on the observed magnetic flux in a rf-SQUID. Quantum measurement theory is shown to predict violations of these inequalities only when the flux states corresponding to opposite current senses are not distinguishable. Thus rf-SQUIDs cannot help to discriminate realism and quantum mechanics at the macroscopic level.Comment: 12 pages, 4 Postscript figures in an uuencoded file figures.uu, uses revtex.st

Aerosol-type classification based on AERONET version 3 inversion products

© Author(s) 2019. This work is distributed under the Creative Commons Attribution 4.0 License.This study proposes an aerosol-type classification based on the particle linear depolarization ratio (PLDR) and single-scattering albedo (SSA) provided in the AErosol RObotic NETwork (AERONET) version 3 level 2.0 inversion product. We compare our aerosol-type classification with an earlier method that uses fine-mode fraction (FMF) and SSA. Our new method allows for a refined classification of mineral dust that occurs as a mixture with other absorbing aerosols: pure dust (PD), dust-dominated mixed plume (DDM), and pollutant-dominated mixed plume (PDM). We test the aerosol classification at AERONET sites in East Asia that are frequently affected by mixtures of Asian dust and biomass-burning smoke or anthropogenic pollution. We find that East Asia is strongly affected by pollution particles with high occurrence frequencies of 50 % to 67 %. The distribution and types of pollution particles vary with location and season. The frequency of PD and dusty aerosol mixture (DDM+PDM) is slightly lower (34 % to 49 %) than pollution-dominated mixtures. Pure dust particles have been detected in only 1 % of observations. This suggests that East Asian dust plumes generally exist in a mixture with pollution aerosols rather than in pure form. In this study, we have also considered data from selected AERONET sites that are representative of anthropogenic pollution, biomass-burning smoke, and mineral dust. We find that average aerosol properties obtained for aerosol types in our PLDR–SSA-based classification agree reasonably well with those obtained at AERONET sites representative for different aerosol types.Peer reviewe

Europe's Banking Union: what progress has been made?

The creation of a European Banking Union was seen as one of the key responses to the Eurozone crisis. But despite being agreed in 2012, the banking union remains incomplete. Tobias Tesche assesses the progress that has been made so far, writing that the banking union has so far failed to deliver on its promises

Profiling of fine and coarse particle mass : Case studies of Saharan dust and Eyjafjallajökull/Grimsvötn volcanic plumes

© Author(s) 2012. This work is distributed under the Creative Commons Attribution 3.0 LicenseThe polarization lidar photometer networking (POLIPHON) method introduced to separate coarse-mode and fine-mode particle properties of Eyjafjallajokull volcanic aerosols in 2010 is extended to cover Saharan dust events as well. Furthermore, new volcanic dust observations performed after the Grimsvotn volcanic eruptions in 2011 are presented. The retrieval of particle mass concentrations requires mass-specific extinction coefficients. Therefore, a review of recently published mass-specific extinction coefficients for Saharan dust and volcanic dust is given. Case studies of four different scenarios corroborate the applicability of the profiling technique: (a) Saharan dust outbreak to central Europe, (b) Saharan dust plume mixed with biomass-burning smoke over Cape Verde, and volcanic aerosol layers originating from (c) the Eyjafjallajokull eruptions in 2010 and (d) the Grimsvotn eruptions in 2011. Strong differences in the vertical aerosol layering, aerosol mixing, and optical properties are observed for the different volcanic eventsPeer reviewe