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Recent variability of the solar spectral irradiance and its impact on climate modelling
Ermolli, I.,Matthes, K.,Dudok de Wit, T.,Krivova, N. A.,Tourpali, K.,Weber, M.,Unruh, Y. C.,Gray, L.,Langematz, U.,Pilewskie, P.,Rozanov, E.,Schmutz, W.,Shapiro, A.,Solanki, S. K.,Woods, T. N. Copernicus GmbH 2013 Atmospheric chemistry and physics Vol.13 No.8
<P>Abstract. The lack of long and reliable time series of solar spectral irradiance (SSI) measurements makes an accurate quantification of solar contributions to recent climate change difficult. Whereas earlier SSI observations and models provided a qualitatively consistent picture of the SSI variability, recent measurements by the SORCE (SOlar Radiation and Climate Experiment) satellite suggest a significantly stronger variability in the ultraviolet (UV) spectral range and changes in the visible and near-infrared (NIR) bands in anti-phase with the solar cycle. A number of recent chemistry-climate model (CCM) simulations have shown that this might have significant implications on the Earth's atmosphere. Motivated by these results, we summarize here our current knowledge of SSI variability and its impact on Earth's climate. We present a detailed overview of existing SSI measurements and provide thorough comparison of models available to date. SSI changes influence the Earth's atmosphere, both directly, through changes in shortwave (SW) heating and therefore, temperature and ozone distributions in the stratosphere, and indirectly, through dynamical feedbacks. We investigate these direct and indirect effects using several state-of-the art CCM simulations forced with measured and modelled SSI changes. A unique asset of this study is the use of a common comprehensive approach for an issue that is usually addressed separately by different communities. We show that the SORCE measurements are difficult to reconcile with earlier observations and with SSI models. Of the five SSI models discussed here, specifically NRLSSI (Naval Research Laboratory Solar Spectral Irradiance), SATIRE-S (Spectral And Total Irradiance REconstructions for the Satellite era), COSI (COde for Solar Irradiance), SRPM (Solar Radiation Physical Modelling), and OAR (Osservatorio Astronomico di Roma), only one shows a behaviour of the UV and visible irradiance qualitatively resembling that of the recent SORCE measurements. However, the integral of the SSI computed with this model over the entire spectral range does not reproduce the measured cyclical changes of the total solar irradiance, which is an essential requisite for realistic evaluations of solar effects on the Earth's climate in CCMs. We show that within the range provided by the recent SSI observations and semi-empirical models discussed here, the NRLSSI model and SORCE observations represent the lower and upper limits in the magnitude of the SSI solar cycle variation. The results of the CCM simulations, forced with the SSI solar cycle variations estimated from the NRLSSI model and from SORCE measurements, show that the direct solar response in the stratosphere is larger for the SORCE than for the NRLSSI data. Correspondingly, larger UV forcing also leads to a larger surface response. Finally, we discuss the reliability of the available data and we propose additional coordinated work, first to build composite SSI data sets out of scattered observations and to refine current SSI models, and second, to run coordinated CCM experiments. </P>
The Problems and Opportunities of Content-based Analysis and Description of Ethnic Music
Dirk Moelants,Olmo Cornelis,Marc Leman,Jos Gansemans,Rita De Caluwe,Guy De Tré,Tom Matthé,Axel Hallez 국립민속박물관 2007 International Journal of Intangible Heritage Vol.2 No.-
The Belgian Royal Museum for Central-Africa (RMCA)holds a large collection of ethnographic artifacts, includinga sound archive with music recordings from the early 20thCentury up to recently. The archive is one of the biggestand best-documented archives worldwide for the region ofCentral Africa. An on-going digitisation project is part of astrategy to conserve this archive and make it accessible tothe public by (i) the digitisation of the data, and (ii) theapplication of music information retrieval techniques forthe digitised data. While state-of-the-art research in musicinformation retrieval aims to search and retrieve music onthe basis of content description, most of the existing toolsare designed for Western music collections, without anyguarantee that these techniques can be applied to musicfrom other cultures. African music, in particular, createsnew challenges for content-based description andinformation retrieval. This paper describes some generalproblems regarding the content-based description ofAfrican and other non-Western music. It suggests anapproach for describing pitch structures which will allowfor the description of both Western music and non-Westernmusic.
Oh, Young-Suk,Kenea, S. Takele,Goo, Tae-Young,Chung, Kyu-Sun,Rhee, Jae-Sang,Ou, Mi-Lim,Byun, Young-Hwa,Wennberg, Paul O.,Kiel, Matthä,us,DiGangi, Joshua P.,Diskin, Glenn S.,Velazco, Voltaire A.,Gr Copernicus GmbH 2018 Atmospheric measurement techniques Vol.11 No.4
<P><p><strong>Abstract.</strong> Since the late 1990s, the meteorological observatory established in Anmyeondo (36.5382°<span class='thinspace'></span>N, 126.3311°<span class='thinspace'></span>E, and 30<span class='thinspace'></span>m above mean sea level) has been monitoring several greenhouse gases such as CO<sub>2</sub>, CH<sub>4</sub>, N<sub>2</sub>O, CFCs, and SF<sub>6</sub> as a part of the Global Atmosphere Watch (GAW) Program. A high resolution ground-based (g-b) Fourier transform spectrometer (FTS) was installed at this observation site in 2013 and has been operated within the frame work of the Total Carbon Column Observing Network (TCCON) since August 2014. The solar spectra recorded by the g-b FTS cover the spectral range 3800 to 16<span class='thinspace'></span>000<span class='thinspace'></span>cm<sup>−1</sup> at a resolution of 0.02<span class='thinspace'></span>cm<sup>−1</sup>. In this work, the GGG2014 version of the TCCON standard retrieval algorithm was used to retrieve total column average CO<sub>2</sub> and CH<sub>4</sub> dry mole fractions (XCO<sub>2</sub>, XCH<sub>4</sub>) and from the FTS spectra. Spectral bands of CO<sub>2</sub> (at 6220.0 and 6339.5<span class='thinspace'></span>cm<sup>−1</sup> center wavenumbers, CH<sub>4</sub> at 6002<span class='thinspace'></span>cm<sup>−1</sup> wavenumber, and O<sub>2</sub> near 7880<span class='thinspace'></span>cm<sup>−1</sup> ) were used to derive the XCO<sub>2</sub> and XCH<sub>4</sub>. In this paper, we provide comparisons of XCO<sub>2</sub> and XCH<sub>4</sub> between the aircraft observations and g-b FTS over Anmyeondo station. A comparison of 13 coincident observations of XCO<sub>2</sub> between g-b FTS and OCO-2 (Orbiting Carbon Observatory) satellite measurements are also presented for the measurement period between February 2014 and November 2017. OCO-2 observations are highly correlated with the g-b FTS measurements (<i>r</i><sup>2</sup> = 0.884) and exhibited a small positive bias (0.189<span class='thinspace'></span>ppm). Both data set capture seasonal variations of the target species with maximum and minimum values in spring and late summer, respectively. In the future, it is planned to further utilize the FTS measurements for the evaluation of satellite observations such as Greenhouse Gases Observing Satellite (GOSAT, GOSAT-2). This is the first report of the g-b FTS observations of XCO<sub>2</sub> species over the Anmyeondo station.</p> </P>
Valentino, Francesco,Daddi, Emanuele,Finoguenov, Alexis,Strazzullo, Veronica,Brun, Amandine Le,Vignali, Cristian,Bournaud, Fré,dé,ric,Dickinson, Mark,Renzini, Alvio,Bé,thermin, Matth American Astronomical Society 2016 The Astrophysical journal Vol.829 No.1
<P>We present the discovery of a giant >= 100 kpc Ly alpha nebula detected in the core of the X-ray emitting cluster CL J1449 +0856 at z = 1.99 through Keck/LRIS narrow-band imaging. This detection extends the known relation between Lya nebulae and overdense regions of the universe to the dense core of a 5-7 x 10(13) M-circle dot cluster. The most plausible candidates to power the nebula are two Chandra-detected AGN host cluster members, while cooling from the X-ray phase and cosmological cold flows are disfavored primarily because of the high Ly alpha to X-ray luminosity ratio (L-Ly alpha/L-X approximate to 0.3, greater than or similar to 10-1000 times. higher than in local cool-core clusters) and by current modeling. Given the physical conditions of the Ly alpha-emitting gas and the possible interplay with the X-ray phase, we argue that the Ly alpha nebula would be short-lived (less than or similar to 10 Myr) if not continuously replenished with cold gas at a rate of greater than or similar to 1000 M-circle dot yr(-1). We investigate the possibility that cluster galaxies supply the required gas through outflows and we show that their total mass outflow rate matches the replenishment necessary to sustain the nebula. This scenario directly implies the extraction of energy from galaxies and its deposition in the surrounding intracluster medium (ICM), as required to explain the thermodynamic properties of local clusters. We estimate an energy injection of the order of approximate to 2 keV per particle in the ICM over a 2 Gyr interval. In our baseline calculation, AGNs provide up to 85% of the injected energy and two-thirds. of the mass, while the rest is supplied by supernovae-driven winds.</P>