310 research outputs found

    Anatomizing Civil War

    Get PDF
    Imperial Latin epic has seen a renaissance of scholarly interest. This book illuminates the work of the poet Lucan, a contemporary of the emperor Nero who as nephew of the imperial adviser Seneca moved in the upper echelons of Neronian society. This young and maverick poet, whom Nero commanded to commit suicide at the age of 26, left an epic poem on the civil war between Caesar and Pompey that epitomizes the exuberance and stylistic experimentation of Neronian culture. This study focuses on Lucan's epic technique and traces his influence through the Middle Ages and the Renaissance. Martin T. Dinter's newest volume engages with Lucan's use of body imagery, sententiae, Fama (rumor), and open-endedness throughout his civil war epic. Although Lucan's Bellum Civile is frequently decried as a fragmented as well as fragmentary epic, this study demonstrates how Lucan uses devices other than teleology and cohesive narrative structure to bind together the many parts of his epic body

    Remote sensing of coccolithophore blooms in selected oceanic regions using the PhytoDOAS method applied to hyper-spectral satellite data

    Get PDF
    In this study temporal variations of coccolithophore blooms are investigated using satellite data. Eight years (from 2003 to 2010) of data of SCIAMACHY, a hyper-spectral satellite sensor on-board ENVISAT, were processed by the PhytoDOAS method to monitor the biomass of coccolithophores in three selected regions. These regions are characterized by frequent occurrence of large coccolithophore blooms. The retrieval results, shown as monthly mean time series, were compared to related satellite products, including the total surface phytoplankton, i.e. total chlorophyll a (from GlobColour merged data) and the particulate inorganic carbon (from MODIS-Aqua). The inter-annual variations of the phytoplankton bloom cycles and their maximum monthly mean values have been compared in the three selected regions to the variations of the geophysical parameters: sea-surface temperature (SST), mixed-layer depth (MLD) and surface wind-speed, which are known to affect phytoplankton dynamics. For each region, the anomalies and linear trends of the monitored parameters over the period of this study have been computed. The patterns of total phytoplankton biomass and specific dynamics of coccolithophore chlorophyll a in the selected regions are discussed in relation to other studies. The PhytoDOAS results are consistent with the two other ocean color products and support the reported dependencies of coccolithophore biomass dynamics on the compared geophysical variables. This suggests that PhytoDOAS is a valid method for retrieving coccolithophore biomass and for monitoring its bloom developments in the global oceans. Future applications of time series studies using the PhytoDOAS data set are proposed, also using the new upcoming generations of hyper-spectral satellite sensors with improved spatial resolution

    A enargeia épica ou a falta de ekphrasis na Guerra Civil de Lucano

    Get PDF
    This paper plunges into the thick of Latin poetry to interrogate one particular example of epic’s engagement with the visual: ekphrasis. It considers how the theoretical approach of “intermediality” can provide a framework for exploring the blurring of ekphrastic and narrative modes in Latin epic. This framework helps us better understand the relationship of art and text in Latin epic in general and the workings of epic construction.Este estudo mergulha no íntimo da poesia latina a fim de questionar um exemplo particular de engajamento épico com o visual: a ekphrasis. Ele considera como a abordagem teórica da “intermidialidade” pode nos fornecer um parâmetro para explorar a imbricação dos modos narrativo e ecfrástico na épica latina. Tal parâmetro permite a melhor compreensão da relação entre arte e texto na épica latina de um modo geral, bem como do funcionamento da construção épica

    Sententiae na épica latina

    Get PDF
    This paper examines Virgil’s and Lucan’s sententiae, a much-neglected thetorical feature of Latin epic. While Virgil’s sententiae are frequently quoted by later authors, Lucan in particular was famous for his highly rhetorical sententiae in antiquity (cf. Quint. Inst. 10.1.90). Lucan strives on the syntactic level to create unique and memorable phrases, which secure the Nachleben of his epic body through excerptability. Reading of Lucan as a mine for one-liners is no modern imposition, but instead confirms that this style of reading brings out the strength of the poem’s energetic formulation of its key themes such as downfall and flight: sententiae lay down the epic’s laws and simultaneously create a discourse on epic values that spans the entire epic.Este artigo examina as sententiae, um expediente retórico bastante negligenciado da épica latina, em Virgílio e Lucano. Enquanto as sententiae de Virgílio são frequentemente citadas por autores posteriores, Lucano, em particular, ficou famoso na Antiguidade por suas sententiae altamente retóricas (Inst. Or. 10.1.90). Lucano concentra seus esforços no nível sintático a fim de criar frases únicas e memoráveis, as quais asseguram o Nachleben de seu épico – haja vista que são extraíveis de seus contextos originais e realocáveis em novos contextos. Ler Lucano como uma mina de versos singulares não é uma imposição moderna, mas, ao contrário, confirma que este estilo de leitura exibe a força de formulações enérgicas sobre temas-chave da épica lucaniana, tais como derrocada e fuga. As sententiae estabelecem as leis da épica e, simultaneamente, criam um discurso sobre valores que se estendem por toda a épica

    Cloud and surface classification using SCIAMACHY polarization measurement devices

    Get PDF
    International audienceA simple scheme has been developed to discriminate surface, sun glint and cloud properties in satellite based spectrometer data utilizing visible and near infrared information. It has been designed for the use with data measured by SCIAMACHY's (SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY) Polarization Measurement Devices but the applicability is not strictly limited to this instrument. The scheme is governed by a set of constraints and thresholds developed by using satellite imagery and meteorological data. Classification targets are ice, water and generic clouds, sun glint and surface parameters, such as water, snow/ice, desert and vegetation. The validation is done using MERIS (MEdium Resolution Imaging Spectrometer) and meteorological data from METAR (MÉTéorologique Aviation Régulière ? a network for the provision of meteorological data for aviation). Qualitative and quantitative validation using MERIS satellite imagery shows good agreement. The comparison with METAR data exhibits very good agreement

    Spectral studies of ocean water using DOAS

    No full text
    International audienceMethods enabling the retrieval of oceanic parameter from the space borne instrumentation Scanning Imaging Absorption Spectrometer for Atmospheric ChartographY (SCIAMACHY) using Differential Optical Absorption Spectroscopy (DOAS) are presented. SCIAMACHY onboard ENVISAT measures back scattered solar radiation at a spectral resolution (0.2 to 1.5 nm). The DOAS method was used for the first time to fit modelled Vibrational Raman Scattering (VRS) in liquid water and in situ measured phytoplankton absorption reference spectra to optical depths measured by SCIAMACHY. Spectral structures of VRS and phytoplankton absorption were clearly found in these optical depths. Both fitting approaches lead to consistent results. DOAS fits correlate with estimates of chlorophyll concentrations: low fit factors for VRS retrievals correspond to large chlorophyll concentrations and vice versa; large fit factors for phytoplankton absorption correspond with high chlorophyll concentrations and vice versa. From these results a simple retrieval technique taking advantage of both measurements is shown. First maps of global chlorophyll concentrations were compared to the corresponding MODIS measurements with very promising results. In addition, results from this study will be used to improve atmospheric trace gas DOAS-retrievals from visible wavelengths by including these oceanographic signatures

    Improvement to the PhytoDOAS method for identification of coccolithophores using hyper-spectral satellite data

    Get PDF
    The goal of this study was to improve PhytoDOAS, which is a new retrieval method for quantitative identification of major phytoplankton functional types (PFTs) using hyper-spectral satellite data. PhytoDOAS is an extension of the Differential Optical Absorption Spectroscopy (DOAS, a method for detection of atmospheric trace gases), developed for remote identification of oceanic phytoplankton groups. Thus far, PhytoDOAS has been successfully exploited to identify cyanobacteria and diatoms over the global ocean from SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) hyper-spectral data. This study aimed to improve PhytoDOAS for remote identification of coccolithophores, another functional group of phytoplankton. The main challenge for retrieving more PFTs by PhytoDOAS is to overcome the correlation effects between different PFT absorption spectra. Different PFTs are composed of different types and amounts of pigments, but also have pigments in common, e.g. chl <i>a</i>, causing correlation effects in the usual performance of the PhytoDOAS retrieval. Two ideas have been implemented to improve PhytoDOAS for the PFT retrieval of more phytoplankton groups. Firstly, using the fourth-derivative spectroscopy, the peak positions of the main pigment components in each absorption spectrum have been derived. After comparing the corresponding results of major PFTs, the optimized fit-window for the PhytoDOAS retrieval of each PFT was determined. Secondly, based on the results from derivative spectroscopy, a simultaneous fit of PhytoDOAS has been proposed and tested for a selected set of PFTs (coccolithophores, diatoms and dinoflagellates) within an optimized fit-window, proven by spectral orthogonality tests. The method was then applied to the processing of SCIAMACHY data over the year 2005. Comparisons of the PhytoDOAS coccolithophore retrievals in 2005 with other coccolithophore-related data showed similar patterns in their seasonal distributions, especially in the North Atlantic and the Arctic Sea. The seasonal patterns of the PhytoDOAS coccolithophores indicated very good agreement with the coccolithophore modeled data from the NASA Ocean Biochemical Model (NOBM), as well as with the global distributions of particulate inorganic carbon (PIC), provided by MODIS (MODerate resolution Imaging Spectroradiometer)-Aqua level-3 products. Moreover, regarding the fact that coccolithophores belong to the group of haptophytes, the PhytoDOAS seasonal coccolithophores showed good agreement with the global distribution of haptophytes, derived from synoptic pigment relationships applied to SeaWiFS chl <i>a</i>. As a case study, the simultaneous mode of PhytoDOAS has been applied to SCIAMACHY data for detecting a coccolithophore bloom which was consistent with the MODIS RGB image and the MODIS PIC map of the bloom, indicating the functionality of the method also in short-term retrievals

    High resolution water column phytoplankton composition across the Atlantic Ocean from ship-towed vertical undulating radiometry.

    Get PDF
    Different phytoplankton groups dominate ocean biomes and they drive differently the marine food web and the biogeochemical cycles. However, their distribution over most parts of the global ocean remains uncertain due to limitations in the sampling resolution of currently available in situ and satellite data. Information below surface waters are especially limited because satellite sensors only provide information on the first optical depth. We present measurements obtained during Polarstern cruise PS113 (May–June 2018) across the Atlantic Ocean from South America to Europe along numerous transects. We measured the hyperspectral underwater radiation field continuously over several hours from a vertical undulating platform towed behind the ship. Equivalent measurements were also taken at specific stations. The concentrations of phytoplankton pigments were determined on discrete water samples. Via diagnostic pigment analysis we derived the phytoplankton group chlorophyll a concentration (Chla) from this pigment data set. We obtained high resolution phytoplankton group Chla data from depth resolved apparent optical properties derived from the underwater radiation data by applying an empirical orthogonal function (EOF) analysis to the spectral data set and subsequently developing regression models using the pigment based phytoplankton group Chla and selected EOF modes. To our knowledge, this is the first data set with high horizontal coverage (50–150 km) and resolution (∼1 km) that is also resolved vertically for the Chla of major taxonomic phytoplankton groups. Subsampling with 500 permutations for cross validation verified the high robustness of our estimates to enable predictions of seven different phytoplankton groups’ Chla and of total Chla (R2 and median percent differences of the cross validation are within 0.45–0.68 and 29–53%, respectively). Our depth resolved phytoplankton groups’ Chla data reflect well the different biogeochemical provinces within the Atlantic Ocean transect and follow the distributions encountered by previous point observations. This verifies the high quality of our retrievals and provides the prospect to put similar radiometers on profiling floats or gliders which would enable the large-scale collection of vertically resolved phytoplankton data at much improved horizontal coverage relative to discrete sampling
    corecore