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  • 1
    Publikationsdatum: 2021-06-16
    Beschreibung: While a quantitative climate theory of tropical cyclone formation remains elusive, considerable progress has been made recently in our ability to simulate tropical cyclone climatologies and understand the relationship between climate and tropical cyclone formation. Climate models are now able to simulate a realistic rate of global tropical cyclone formation, although simulation of the Atlantic tropical cyclone climatology remains challenging unless horizontal resolutions finer than 50 km are employed. This article summarizes published research from the idealized experiments of the Hurricane Working Group of U.S. CLIVAR (CLImate VARiability and predictability of the ocean-atmosphere system). This work, combined with results from other model simulations, has strengthened relationships between tropical cyclone formation rates and climate variables such as mid-tropospheric vertical velocity, with decreased climatological vertical velocities leading to decreased tropical cyclone formation. Systematic differences are shown between experiments in which only sea surface temperature is increased versus experiments where only atmospheric carbon dioxide is increased, with the carbon dioxide experiments more likely to demonstrate the decrease in tropical cyclone numbers previously shown to be a common response of climate models in a warmer climate. Experiments where the two effects are combined also show decreases in numbers, but these tend to be less for models that demonstrate a strong tropical cyclone response to increased sea surface temperatures. Further experiments are proposed that may improve our understanding of the relationship between climate and tropical cyclone formation, including experiments with two-way interaction between the ocean and the atmosphere and variations in atmospheric aerosols.
    Beschreibung: Published
    Beschreibung: 997–1017
    Beschreibung: 4A. Clima e Oceani
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): tropical cyclones ; hurricanes ; climate change ; CLIVAR ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Publikationsdatum: 2017-04-04
    Beschreibung: In this work the authors investigate possible changes in the intensity of rainfall events associated 28with tropical cyclones (TCs) under idealized forcing scenarios, including a uniformly warmer climate, with a special focus on landfalling storms. A new set of experiments designed within the U.S. CLIVAR Hurricane Working Group allows disentangling the relative role of changes in atmospheric carbon dioxide from that played by sea surface temperature (SST) in changing theamount of precipitation associated with TCs in a warmer world. Compared to the present day simulation, we found an increase in TC precipitation under the scenarios involving SST increases. On the other hand, in a CO2 doubling-only scenario, the changes in TC rainfall are small and we found that, on average, TC rainfall tends to decrease compared to the present day climate. The results of this study highlight the contribution of landfalling TCs to the projected increase in theprecipitation changes affecting the tropical coastal regions.
    Beschreibung: Published
    Beschreibung: 4642–4654
    Beschreibung: 4A. Clima e Oceani
    Beschreibung: JCR Journal
    Beschreibung: open
    Schlagwort(e): tropical cyclones ; precipitation ; extreme events ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Publikationsdatum: 2017-04-04
    Beschreibung: Future tropical cyclone activity is a topic of great scientific and societal interest. In the absence of a climate theory of tropical cyclogenesis, general circulation models are the primary tool available for investigating the issue. However, the identification of tropical cyclones in model data at moderate resolution is complex, and numerous schemes have been developed for their detection. We here examine the influence of different tracking schemes on detected tropical cyclone activity and responses in the Hurricane Working Group experiments. These are idealized atmospheric general circulation model experiments aimed at determining and distinguishing the effects of increased sea-surface temperature and other increased CO2 effects on tropical cyclone activity. We apply two tracking schemes to these data and also analyze the tracks provided by each modelling group. Our results indicate moderate agreement between the different tracking methods, with some models and experiments showing better agreement across schemes than others. When comparing responses between experiments, we find that much of the disagreement between schemes is due to differences in duration, wind speed, and formation-latitude thresholds. After homogenisation in these thresholds, agreement between different tracking methods is improved. However, much disagreement remains, accountable for by more fundamental differences between the tracking schemes. Our results indicate that sensitivity testing and selection of objective thresholds are the key factors in obtaining meaningful, reproducible results when tracking tropical cyclones in climate model data at these resolutions, but that more fundamental differences between tracking methods can also have a significant impact on the responses in activity detected.
    Beschreibung: Published
    Beschreibung: 9197–9213
    Beschreibung: 4A. Clima e Oceani
    Beschreibung: JCR Journal
    Beschreibung: restricted
    Schlagwort(e): tropical cyclones ; tracking schemes ; climate change ; hurricanes ; 01. Atmosphere::01.01. Atmosphere::01.01.02. Climate
    Repository-Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Materialart: article
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Publikationsdatum: 2014-06-21
    Beschreibung: Inclusion body myositis (IBM), a degenerative and inflammatory disorder of skeletal muscle, and Alzheimer's disease share protein derangements and attrition of postmitotic cells. Overexpression of cyclins and proliferating cell nuclear antigen (PCNA) and evidence for DNA replication is reported in Alzheimer's disease brain, possibly contributing to neuronal death. It is unknown whether aberrant cell cycle reentry also occurs in IBM. We examined cell cycle markers in IBM compared with normal control, polymyositis (PM) and non-inflammatory dystrophy sample sets. Next, we tested for evidence of reentry and DNA synthesis in C2C12 myotubes induced to express β-amyloid (Aβ42). We observed increased levels of Ki-67, PCNA and cyclins E/D1 in IBM compared with normals and non-inflammatory conditions. Interestingly, PM samples displayed similar increases. Satellite cell markers did not correlate with Ki-67-affected myofiber nuclei. DNA synthesis and cell cycle markers were induced in Aβ-bearing myotubes. Cell cycle marker and cyclin protein expressions were also induced in an experimental allergic myositis-like model of PM in mice. Levels of p21 (Cip1/WAF1), a cyclin-dependent kinase inhibitor, were decreased in affected myotubes. However, overexpression of p21 did not rescue cells from Aβ-induced toxicity. This is the first report of cell cycle reentry in human myositis. The absence of rescue and evidence for reentry in separate models of myodegeneration and inflammation suggest that new DNA synthesis may be a reactive response to either or both stressors.
    Print ISSN: 0964-6906
    Digitale ISSN: 1460-2083
    Thema: Biologie , Medizin
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Publikationsdatum: 2016-08-24
    Beschreibung: In this work, we analyse Jovian Trojans in the space of suitable resonant elements and we identify clusters of possible collisional origin by two independent methods: the hierarchical clustering and a so-called randombox. Compared to our previous work, we study a twice larger sample. Apart from Eurybates, Ennomos and 1996 RJ families, we have found three more clusters – namely families around asteroids (20961) Arkesilaos, (624) Hektor in the L 4 libration zone and (247341) 2001 UV 209 in L 5 . The families fulfill our stringent criteria, i.e. a high statistical significance, an albedo homogeneity and a steeper size–frequency distribution than that of background. In order to understand their nature, we simulate their long term collisional evolution with the Boulder code and dynamical evolution using a modified SWIFT integrator. Within the framework of our evolutionary model, we were able to constrain the age of the Hektor family to be either 1–4 Gyr or, less likely, 0.1–2.5 Gyr, depending on initial impact geometry. Since (624) Hektor itself seems to be a bilobed-shape body with a satellite, i.e. an exceptional object, we address its association with the D-type family and we demonstrate that the moon and family could be created during a single impact event. We simulated the cratering event using a smoothed particle hydrodynamics. This is also the first case of a family associated with a D-type parent body.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2013-07-26
    Beschreibung: Evidence in the Solar system suggests that the giant planets underwent an epoch of radial migration that was very rapid, with an e-folding time-scale shorter than 1 Myr. It is probable that the cause of this migration was that the giant planets experienced an orbital instability that caused them to encounter each other, resulting in radial migration. A promising and heavily studied way to accomplish such a fast migration is for Jupiter to have scattered one of the ice giants outwards; this event has been called the ‘jumping Jupiter’ scenario. Several works suggest that this dynamical instability occurred ‘late’, long after all the planets had formed and the solar nebula had dissipated. Assuming that the terrestrial planets had already formed, then their orbits would have been affected by the migration of the giant planets as many powerful resonances would sweep through the terrestrial planet region. This raises two questions. First, what is the expected increase in dynamical excitement of the terrestrial planet orbits caused by late and very fast giant planet migration? And secondly, assuming that the migration occurred late, can we use this migration of the giant planets to obtain information on the primordial orbits of the terrestrial planets? In this work, we attempt to answer both of these questions using numerical simulations. We directly model a large number of terrestrial planet systems and their response to the smooth migration of Jupiter and Saturn, and also two jumping Jupiter simulations. We study the total dynamical excitement of the terrestrial planet system with the angular momentum deficit (AMD) value, including the way it is shared among the planets. We conclude that to reproduce the current AMD with a reasonable probability (~20 per cent) after late rapid giant planet migration and a favourable jumping Jupiter evolution, the primordial AMD should have been lower than ~70 per cent of the current value, but higher than 10 per cent. We find that a late giant planet migration scenario that initially had five giant planets rather than four had a higher probability of satisfying the orbital constraints of the terrestrial planets. Assuming late migration, we predict that Mars was initially on an eccentric and inclined orbit while the orbits of Mercury, Venus and Earth were more circular and coplanar. The lower primordial dynamical excitement and the peculiar partitioning between planets impose new constraints for terrestrial planet formation simulations.
    Print ISSN: 0035-8711
    Digitale ISSN: 1365-2966
    Thema: Physik
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 2017-08-04
    Print ISSN: 0894-8755
    Digitale ISSN: 1520-0442
    Thema: Geographie , Geologie und Paläontologie , Physik
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
  • 9
    Publikationsdatum: 2002-01-01
    Print ISSN: 0021-924X
    Digitale ISSN: 1756-2651
    Thema: Biologie , Chemie und Pharmazie
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2007-05-15
    Beschreibung: Objectively derived resolution-dependent criteria are defined for the detection of tropical cyclones in model simulations and observationally based analyses. These criteria are derived from the wind profiles of observed tropical cyclones, averaged at various resolutions. Both an analytical wind profile model and two-dimensional observed wind analyses are used. The results show that the threshold wind speed of an observed tropical cyclone varies roughly linearly with resolution. The criteria derived here are compared to the numerous different criteria previously employed in climate model simulations. The resulting method provides a simple means of comparing climate model simulations and reanalyses.
    Print ISSN: 0894-8755
    Digitale ISSN: 1520-0442
    Thema: Geographie , Geologie und Paläontologie , Physik
    Standort Signatur Erwartet Verfügbarkeit
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