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Deliverable No. 4.2: Evaluation of the contribution of the Arctic observing system to forecast skill from short/medium-range-to-seasonal time scales
No full textAPPLICATE – GA 727862 Deliverable 4.2
APPLICATE WP4 (‘Support for Arctic observing system design’) demonstrated that numerical models can be successfully used to assess the importance of current Arctic observations for predictive skill in the Arctic and beyond and for guiding the design of future Arctic observing
system. This deliverable summarizes part of this effort made in Task 4.2. This task aimed (i) to assess the importance of current Arctic observing systems for predictive skill from hours to months ahead, (b) to identify which enhancements to the observing systems themselves would contribute to improved predictive skill in the Arctic and beyond and (c) to guide the design of future observing systems in Arctic region. These objectives were accomplished by making use of data denial experiments, in which the quality of the initial conditions of weather predictions is artificially degraded by removing the contribution of a certain observation type, and of historical simulations with various coupled global circulation models.
Coordinated idealized ‘data denial’-type experiments performed with two coupled climate models HadGEM3-GC3 and EC-EARTH, were used to quantify the impact of accurate sea ice thickness initialization on the Arctic sea-ice and atmospheric circulation forecast skill up to a year ahead. These idealized ‘data denial’ experiments consisted in initializing ensemble simulations using degraded sea ice thickness information and comparing the loss of skill with respect to control simulations assumed as the ‘truth’. This provided a theoretical understanding on the improvement of sea ice and atmospheric predictions linked to the sea ice thickness assimilation in coupled prediction systems. It was shown that an accurate sea ice initialization on the 1st of January improves the skill in all performed experiments. In particular, there is a high skill gain for the sea ice volume and extent in January-February and a re-emergence of skill gain from September onwards. The 2m air temperature shows a prediction skill gain in January with some improvements in September. The fact that the two models show a good agreement in terms of the regions where they show either a skill gain or loss increases the confidence in these findings.
Observing System Experiments performed for the first time for Arctic atmospheric observations with a global state-of-the-art numerical weather prediction system (the ECMWF Integrated Forecasting System) were used to demonstrate the value of these observations for short and medium-range weather forecasts. It was demonstrated that all observing systems contribute to forecast skill in the Arctic and mid-latitudes and have complementary positive impacts on forecast skill. Conventional observations play the most important role during winter, emphasizing the need to maintain and further develop conventional observational networks, which are sparse and costly to maintain in polar regions. Satellite microwave observations play the most important role during summer, while for winter the use of these observations is found to be suboptimal due to issues with their assimilation, in particular over snow and sea ice. This is one of the success stories in APPLICATE highlighting that the quality of weather predictions could be further enhanced by increasing the uptake of these observations in numerical weather prediction systems. For this to be achieved investments are needed in all key components of numerical weather prediction systems, i.e. coupled modelling, ensemble and data assimilation techniques and use of observations. Similarly, to the idealized data denial experiments, the fact that the results obtained at ECMWF are corroborated by coordinated observing system experiments performed at other
weather centres in the framework of YOPP, increases the confidence in these results and in the ways forward presented herein and in D4.4.
Finally, Ponsoni et al. (2020) used coupled historical simulations performed in the framework of CMIP with several coupled climate models to test the hypothesis that an ideal sampling strategy, characterized by only a few optimal sampling locations of key parameters, can provide in situ data for statistically reproducing and predicting the interannual sea ice volume (SIV) variability. Indeed, it was shown that four well-placed locations are sufficient for reconstructing about 70% of the SIV anomaly variance. These stations are placed at the transition Chukchi Sea– central Arctic–Beaufort Sea (79.5◦N, 158.0◦W), near the North Pole (88.5◦N, 40.0◦E), at the transition central Arctic–Laptev Sea (81.5◦N, 107.0◦E), and offshore the Canadian Archipelago (82.5◦N, 109.0◦W), in this respective order. These results provide recommendations for the ongoing and upcoming observational initiatives, in terms of an Arctic optimal observing design, for studying and predicting the pan-Arctic SIV and its interannual variability
Data used in 'An inter-comparison of the mass budget of the Arctic sea ice in CMIP6 models' by Ann Keen et al.
No full textData and processing code used in 'An inter-comparison of the mass budget of the Arctic sea ice in CMIP6 models' by Ann Keen, Ed Blockley, David A. Bailey, Jens Boldingh Debernard, Mitchell Bushuk, Steve Delhaye, David Docquier, Daniel Feltham, François Massonnet, Siobhan O’Farrell, Leandro Ponsoni, José M. Rodriguez, David Schroeder, Neil Swart, Takahiro Toyoda, Hiroyuki Tsujino, Martin Vancoppenolle, and Klaus Wyser, to be published in The Cryosphere, 2021
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Brazil Current System: a proposal for using XBT Data in its dynamical investigation
No full textO sistema de correntes composto pela Corrente do Brasil (CB) e Corrente de Contorno Intermediária (CCI), 20°S e 28°S, são talvez um dos menos estudados sistemas de correntes de contorno subtropical de todo oceano. Dentro desta região, a CB desenvolve vigorosos meandros e vórtices. Uma combinação de simulações numéricas e estudos observacionais representam importantes ferramentas para investigar este fenômeno. Medidas diretas de velocidade são raras e usualmente restritas a curtos intervalos de tempo, para que padrões de longo termo sejam descritos. Similarmente, dados hidrográficos quase sinóticos e dados de ADCP são esparsos. Por outro lado, dados de XBT armazenados pela Marinha do Brasil são abundantes. Investigaremos aqui como que perfis de temperatura (T) amostrados por XBT podem complementar a climatologia regional e serem utilizados para gerar campos de inicialização e assimilação para modelos numéricos. Um método para a construção de perfis sintéticos de salinidade (S) é proposto considerando o complexo padrão da curva TS da região, o formato do perfil da temperatura in situ e a salinidade superficial. Mais especificamente, salinidade superficial e o perfil adimensional da temperatura in situ são usados para a reconstrução da salinidade nos primeiros 200 m da coluna de água, para perfis com profundidade local superior a 1899 m. O perfil não dimensional da salinidade climatológica é usado para as reconstruções no intervalo de 900-1300 m. Este perfil é então redimensionalizado usando valores estimados pela relação TS climatológica em seus extremos. A reconstrução do perfil de salinidade nas demais porções da coluna de água se dá pelo ajuste linear de um polinômio S(T), para cada intervalo de 25 m. Também é necessária a extrapolação dos perfis verticais de temperatura a partir da profundidade máxima de 1800 m (máxima profundidade das sondas de XBT) até o fundo. Propusemos aqui a utilização de um perfil climatológico de T não dimensional, para então fazer a redimensionalização e extensão da estrutura vertical de temperatura até a profundidade local. Cálculos geostróficos utilizando dados provenientes de cruzeiros hidrográficos quase sinóticos são empregados para testar a metodologia. Uma comparação entre o método proposto e as velocidades geostróficas calculadas por outras metodologias é conduzida. Esta comparação inclui velocidades geostróficas calculadas mediante salinidade constante (S=35), uma adaptação da teoria baseada em ajustes polinomiais para a curva TS, e mediante um polinômio ajustado diretamente entre anomalia do volume específico e temperatura. O método proposto neste trabalho foi o que melhor reproduziu, em termos médios, a estrutura vertical de correntes e o respectivo transporte de volume associado, dentre todos aqueles testados. Em particular, o transporte de volume da CB foi praticamente idêntico ao valor obtido com os campos in situ.The Brazil Current (BC) and the Intermediate Western Boundary Current (IWBC) between 20°S and 28°S are perhaps two of the less studied subtropical boundary currents of the world ocean. Within this region, the BC develops vigorous meanders and rings. A combination of numerical simulations and observational studies are important tools to unravel these phenomena. Direct current measurements are rare and usually too short to depict the mean, long term circulation patterns. Similarly, quasi-synoptic hydrographic and ADCP data in the region are sparse. On the other hand, XBT data archived by the Brazilian Navy are abundant. Here we investigate how XBT temperature (T) profiles may improve the study region climatology and be used to generate initialization fields for numerical models. A method for constructing synthetic salinity (S) profiles is proposed considering the complex shape of the TS curve of the area, the shape of the in situ temperature profile and surface salinity. More specifically, surface salinity and nondimensionalized in situ temperature profiles are used for reconstructing salinity in the upper 200 m of the water column for locations with local depth greater than 1899 m. The mean nondimensionalized climatological salinity profile is used for the depth interval between 900 and 1300 m. The nondimensionalized profile is then redimensionalized using values estimated by the climatological TS relationship in its extrema. The salinity vertical profile of the remaining portions of the water column by linear fitting S to T each 25 m interval. It is also necessary to vertically extrapolate the temperature profiles from 1800 m (maximum depth reached by the XBT probes) to the ocean bottom. We propose using the nondimensionalized climatological T profile and the values of the temperature sampled at 1800 m as well as the bottom climatological temperature to redimensionalize it and extend the temperature vertical structure to the local depth. Geostrophic calculations using data from recent quasi-synoptic hydrographic surveys in the area are employed to test the methodology. A comparison between the currently proposed method and the geostrophic velocities calculated by other techniques is conducted. This comparison also includes geostrophic velocity estimates considering: constant salinity (S=35), an adaptation of classical techniques based solely on the TS curve shape, and by direct relating specific volume anomaly and temperature. The method proposed in this work is the one which best reproduces the current vertical structure and current volume transport in mean terms among all tested. In particular, the BC volume transport is virtually identical to the values obtained with the in situ fields
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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