MIRACLE-FI at ImageCLEFphoto 2008: Experiences in merging text-based and content-based retrievals

This paper describes the participation of the MIRACLE consortium at the ImageCLEF Photographic Retrieval task of ImageCLEF 2008. In this is new participation of the group, our first purpose is to evaluate our own tools for text-based retrieval and for content-based retrieval using different similarity metrics and the aggregation OWA operator to fuse the three topic images. From the MIRACLE last year experience, we implemented a new merging module combining the text-based and the content-based information in three different ways: FILTER-N, ENRICH and TEXT-FILTER. The former approaches try to improve the text-based baseline results using the content-based results lists. The last one was used to select the relevant images to the content-based module. No clustering strategies were analyzed. Finally, 41 runs were submitted: 1 for the text-based baseline, 10 content-based runs, and 30 mixed experiments merging text and content-based results. Results in general can be considered nearly acceptable comparing with the best results of other groups. Obtained results from textbased retrieval are better than content-based. Merging both textual and visual retrieval we improve the text-based baseline when applying the ENRICH merging algorithm although visual results are lower than textual ones. From these results we were going to try to improve merged results by clustering methods applied to this image collection

La herramienta IDRA (Indexing and Retrieving Automatically)

Se presenta brevemente la herramienta IDRA, con licencia GPL 3.0, que a partir de unas funcionalidades básicas, facilita la agregación de nuevas funcionalidades para la investigación en recuperación de información

Feasibility of Ceilometers Data to Estimate Radiative Forcing Values: Application to Different Conditions around the COVID-19 Lockdown Period

The authors would like to acknowledge to ACTRIS-SPAIN (CGL2017-90884-REDIT), coordinated by Granada University, for providing quality-assured aerosol measurements and acknowledge to AERONET and COPERNICUS Global Land Services for sun-photometer and satellite quality-assured data processing and distribution. The authors also acknowledge to the Atmospheric Modelling & Weather Forecasting Group in the University of Athens, the Earth Science Dpt. from the Barcelona Supercomputing Centre and the Naval Research laboratory for the provision of SKIRON, DREAM/BSCDREAM8b and NAAPs aerosol maps, respectively. Philippe Dubuisson, the developer of the GAME code, is specially acknowledged. Furthermore, the developers of the HYSPLIT model are also acknowledged. The task of identifying African dust events and quantifying the dust contribution in the regions of the Spanish territory has been routinely carried out in the framework of projects funded by the Spanish ministry for the Ecological Transition (MITECO).In this study, the feasibility of using ceilometer signals to retrieve radiative forcing values is evaluated. The Global Atmospheric Model (GAME) radiative transfer model is used to estimate the shortwave and longwave radiative forcing using an aerosol parameterization based on AERONET data and vertical profiles from a Lufft CHM-15k Nimbus ceilometer. First, eight cases confirmed as dusty days are analyzed to check the feasibility of using ceilometer profiles to feed GAME. The obtained radiative forcing estimates are in good agreement with the literature showing negative values in the short wave (SW) (cooling effect) and positive values in the long wave (LW) (heating effect), both at all levels. As in the literature, radiative forcing estimates show a strong dependence on variations in the aerosol optical depth (AOD), solar zenith angle (θz), surface temperature (ST), and single scattering albedo at 440 nm (SSA440). Thus, GAME can be fed using ceilometer measurements obtaining reliable results. Then, as the temporal evolution of the AOD440 between 27 January and 15 June compared to the 6-year weekly AERONET AOD440 average (from 2014 to 2019) shows a decrease because of the lockdown imposed in Spain due to the COVID-19, a total of 37 radiative forcing calculations without African dust, divided into 8 scenarios, are performed in order to check the effect of the lockdown measures in the radiative forcing. It is shown that the decrease in the AOD, during the lockdown, caused a decrease in the cooling effect in the SW spectral range at all levels. Besides, the increase in the ST increased the heating effect of the aerosols in the LW at the top of the atmosphere and the presence of pollution and absorbing particles (SSA440 < 0.90) caused an increase of the heating effect in the LW at the surface. Therefore, the observed variations in the radiative forcing estimates before and during the lockdown are directly related with the decrease in emissions of aerosols related to human activities.Spanish Ministry of Economy and Competitivity (CRISOL) CGL2017-85344-RMadrid Regional Government (TIGAS-CM) Y2018/EMT-5177Maria Sklodowska-Curie IF 796539H2020 programme from the European Union 654109; 87111

Considerations about the determination of the depolarization calibration profile of a two-telescope lidar and its implications for volume depolarization ratio retrieval

We propose a new method for calculating the volume depolarization ratio of light backscattered by the atmosphere and a lidar system that employs an auxiliary telescope to detect the depolarized component. It takes into account the possible error in the positioning of the polarizer used in the auxiliary telescope. The theory of operation is presented and then applied to a few cases for which the actual position of the polarizer is estimated, and the improvement of the volume depolarization ratio in the molecular region is quantified. In comparison to the method used before, i.e., without correction, the agreement between the volume depolarization ratio with correction and the theoretical value in the molecular region is improved by a factor of 2–2.5.Peer ReviewedPostprint (published version

Two-dimensional mineral dust radiative effect calculations from CALIPSO observations over Europe

A demonstration study to examine the feasibility of retrieving dust radiative effects based on combined satellite data from MODIS (Moderate Resolution Imaging Spectroradiometer), CERES (Clouds and the Earth's Radiant Energy System) and CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) lidar vertical profiles along their orbit is presented. The GAME (Global Atmospheric Model) radiative transfer model is used to estimate the shortwave and longwave dust radiative effects below the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite) orbit assuming an aerosol parameterization based on the CALIOP vertical distribution at a horizontal resolution of 5¿km and additional AERONET (Aerosol Robotic Network) data. Two study cases are analyzed: a strong long-range transport mineral dust event (aerosol optical depth, AOD, of 0.52) that originated in the Sahara Desert and reached the United Kingdom and a weaker event (AOD¿=¿0.16) that affected eastern Europe. The radiative fluxes obtained are first validated in terms of radiative efficiency at a single point with space–time colocated lidar ground-based measurements from EARLINET (European Aerosol Research Lidar Network) stations below the orbit. The methodology is then applied to the full orbit. The strong dependence of the radiative effects on the aerosol load (and to a lesser extent on the surface albedo) highlights the need for accurate AOD measurements for radiative studies. The calculated dust radiative effects and heating rates below the orbits are in good agreement with previous studies of mineral dust, with the radiative efficiency obtained at the surface ranging between -80.3 and -63.0¿W¿m-2 for lower dust concentration event and -119.1 and -79.3¿W¿m-2 for the strong event. Thus, results demonstrate the validity of the method presented here to retrieve 2-D accurate radiative properties with large spatial and temporal coverage.Peer ReviewedPostprint (published version

Calibration of Raman lidar water vapor mixing ratio measurements using zenithal measurements of diffuse sunlight and a radiative transfer model

This is a postprint (author final draft) version of article that has been accepted for publication. A fully version can be found at: https://doi.org/10.1109/TGRS.2018.2851064 © 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Among the different techniques available for measuring the atmospheric water vapor content, Raman lidars stand out as accurate instruments providing detailed profiles with high temporal and altitude resolution. Their principle is based on obtaining the range-resolved ratio of the lidar signals corresponding to Raman returns from water vapor and nitrogen molecules, which is proportional to the water vapor mixing ratio. To do this, it is necessary to determine a calibration factor, specific of each lidar instrument. A method for obtaining this parameter, based on zenith measurements of diffuse sunlight, on Raman scattering models and on simulations, using a radiative transfer model, to estimate sky radiances at the wavelengths of interest, has been applied to the lidar system of Universitat Politècnica de Catalunya (UPC; Technical University of Catalonia, Barcelona, Spain). A set of calibrations, performed between 2016 and 2017, has permitted assessing the calibration procedure and analyzing the stability of the calibration factor in the UPC instrument. Results show that although the calibration factor can remain stable for long periods of time, it can suffer sudden variations that make indispensable to implement a convenient and reliable procedure to perform regular calibrations. We show that the method, which can be applied to any lidar with water vapor and nitrogen Raman channels, can completely dispense with radiosonde data. The calibration method is validated by comparison with simultaneous radiosonde water vapor measurements. Limitations of radiosondes for validating--and eventually calibrating--water vapor Raman lidars have been revealed.Peer ReviewedPostprint (author's final draft

MIRACLE (FI) at ImageCLEFphoto 2009

The Miracle-FI participation at ImageCLEF 2009 photo retrieval task main goal was to improve the merge of content-based and text-based techniques in our experiments. The global system includes our own implemented tool IDRA (InDexing and Retrieving Automatically), and the Valencia University CBIR system. Analyzing both “topics_part1.txt” and “topics_part2.txt” task topics files, we have built different queries files, eliminating the negative sentences with the text from title and clusterTitle or clusterDescription, one query for each cluster (or not) of each topic from 1 to 25 and one for each of the three images of each topic from 26 to 50. In the CBIR system the number of low-level features has been increased from the 68 component used at ImageCLEF 2008 up to 114 components, and in this edition only the Mahalanobis distance has been used in our experiments. Three different merging algorithms were developed in order to fuse together different results lists from visual or textual modules, different textual indexations, or cluster level results into a unique topic level results list. For the five runs submitted we observe that MirFI1, MirFI2 and MifFI3 obtain quite higher precision values than the average ones. Experiment MirFI1, our best run for precision metrics (very similar to MirFI2 and MirFI3), appears in the 16th position in R-Precision classification and in the 19th in MAP one (from a total of 84 submitted experiments). MirFI4 and MirFI5 obtain our best diversity values, appearing in position 11th (over 84) in cluster recall classification, and being the 5th best group from all the 19 participating ones

An architecture providing depolarization ratio capability for a multi-wavelength Raman lidar: implementation and first measurements

A new architecture for the measurement of depolarization produced by atmospheric aerosols with a Raman lidar is presented. The system uses two different telescopes: one for depolarization measurements and another for total-power measurements. The system architecture and principle of operation are described. The first experimental results are also presented, corresponding to a collection of atmospheric conditions over the city of Barcelona.Peer ReviewedPostprint (published version

Raman and infrared spectroscopy of Sr2B′UO6 (B′ = Ni; Co) double perovskites

Temperature dependent normal modes and lattice thermal expansion of Sr 2B′UO6 (B′ = Ni, Co) double perovskites were investigated by Raman/infrared spectroscopies and synchrotron X-ray diffraction, respectively. Monoclinic crystal structures with space group P21/n were confirmed for both compounds, with no clear structural phase transition between 10 and 400 K. As predicted for this structure, the first-order Raman and infrared spectra show a plethora of active modes. In addition, the Raman spectra reveal an enhancement of the integrated area of an oxygen stretching mode, which is also observed in higher-order Raman modes, and an anomalous softening of ∼1 cm-1 upon cooling below T* ∼ 300 K. In contrast, the infrared spectra show conventional temperature dependence. The band profile phonon anomalies are possibly related to an unspecified electronic property of Sr2B′UO6 (B′ = Ni, Co).Centro de Química Inorgánic

Raman and infrared spectroscopy of Sr2B′UO6 (B′ = Ni; Co) double perovskites

Temperature dependent normal modes and lattice thermal expansion of Sr 2B′UO6 (B′ = Ni, Co) double perovskites were investigated by Raman/infrared spectroscopies and synchrotron X-ray diffraction, respectively. Monoclinic crystal structures with space group P21/n were confirmed for both compounds, with no clear structural phase transition between 10 and 400 K. As predicted for this structure, the first-order Raman and infrared spectra show a plethora of active modes. In addition, the Raman spectra reveal an enhancement of the integrated area of an oxygen stretching mode, which is also observed in higher-order Raman modes, and an anomalous softening of ∼1 cm-1 upon cooling below T* ∼ 300 K. In contrast, the infrared spectra show conventional temperature dependence. The band profile phonon anomalies are possibly related to an unspecified electronic property of Sr2B′UO6 (B′ = Ni, Co).Centro de Química Inorgánic