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  • 1
    In: Journal of Clinical Immunology, Springer Science and Business Media LLC, Vol. 43, No. 1 ( 2023-01), p. 46-56
    Abstract: Almost 2 years into the pandemic and with vaccination of children significantly lagging behind adults, long-term pediatric humoral immune responses to SARS-CoV-2 are understudied. The C19.CHILD Hamburg (COVID-19 Child Health Investigation of Latent Disease) Study is a prospective cohort study designed to identify and follow up children and their household contacts infected in the early 2020 first wave of SARS-CoV-2. We screened 6113 children  〈  18 years by nasopharyngeal swab-PCR in a low-incidence setting after general lockdown, from May 11 to June 30, 2020. A total of 4657 participants underwent antibody testing. Positive tests were followed up by repeated PCR and serological testing of all household contacts over 6 months. In total, the study identified 67 seropositive children (1.44%); the median time after infection at first presentation was 83 days post-symptom onset (PSO). Follow-up of household contacts showed less than 100% seroprevalence in most families, with higher seroprevalence in families with adult index cases compared to pediatric index cases (OR 1.79, P  = 0.047). Most importantly, children showed sustained seroconversion up to 9 months PSO, and serum antibody concentrations persistently surpassed adult levels (ratio serum IgG spike children vs. adults 90 days PSO 1.75, P   〈  0.001; 180 days 1.38, P  = 0.01; 270 days 1.54, P  = 0.001). In a low-incidence setting, SARS-CoV-2 infection and humoral immune response present distinct patterns in children including higher antibody levels, and lower seroprevalence in families with pediatric index cases. Children show long-term SARS-CoV-2 antibody responses. These findings are relevant to novel variants with increased disease burden in children, as well as for the planning of age-appropriate vaccination strategies.
    Type of Medium: Online Resource
    ISSN: 0271-9142 , 1573-2592
    RVK:
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2023
    detail.hit.zdb_id: 2016755-6
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  • 2
    In: Atmosphere, MDPI AG, Vol. 11, No. 3 ( 2020-02-26), p. 227-
    Abstract: Simulations of a Regional Climate Model (RCM) driven by identical lateral boundary conditions but initialized at different times exhibit the phenomenon of so-called internal model variability (or in short, Internal Variability—IV), which is defined as the inter-member spread between members in an ensemble of simulations. Our study investigates the effects of air-sea coupling on IV of the regional atmospheric model COSMO-CLM (CCLM) of the new regional coupled system model GCOAST-AHOI (Geesthacht Coupled cOAstal model SysTem: Atmosphere, Hydrology, Ocean and Sea Ice). We specifically address physical processes parameterized in CCLM, which may cause a large IV during an extreme event, and where this IV is affected by the air-sea coupling. Two six-member ensemble simulations were conducted with GCOAST-AHOI and the stand-alone CCLM (CCLM_ctr) for a period of 1 September–31 December 2013 over Europe. IV is expressed by spreads within the two sets of ensembles. Analyses focus on specific events during this period, especially on the storm Christian occurring from 27 to 29 October 2013 in northern Europe. Results show that simulations of CCLM_ctr vary largely amongst ensemble members during the storm. By analyzing two members of CCLM_ctr with opposite behaviors, we found that the large uncertainty in CCLM_ctr is caused by a combination of two factors (1) uncertainty in parameterization of cloud-radiation interaction in the atmospheric model. and (2) lack of an active two-way air-sea interaction. When CCLM is two-way coupled with the ocean model, the ensemble means of GCOAST-AHOI and CCLM_ctr are relatively similar, but the spread is reduced remarkably in GCOAST-AHOI, not only over the ocean where the coupling is done but also over land due to the land-sea interactions.
    Type of Medium: Online Resource
    ISSN: 2073-4433
    Language: English
    Publisher: MDPI AG
    Publication Date: 2020
    detail.hit.zdb_id: 2605928-9
    SSG: 23
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  • 3
    In: Water, MDPI AG, Vol. 13, No. 4 ( 2021-02-05), p. 415-
    Abstract: This study investigates the effects of wind–wave processes in a coupled wave–ocean circulation model on Lagrangian transport simulations. Drifters deployed in the southern North Sea from May to June 2015 are used. The Eulerian currents are obtained by simulation from the coupled circulation model (NEMO) and the wave model (WAM), as well as a stand-alone NEMO circulation model. The wave–current interaction processes are the momentum and energy sea state dependent fluxes, wave-induced mixing and Stokes–Coriolis forcing. The Lagrangian transport model sensitivity to these wave-induced processes in NEMO is quantified using a particle drift model. Wind waves act as a reservoir for energy and momentum. In the coupled wave–ocean circulation model, the momentum that is transferred into the ocean model is considered as a fraction of the total flux that goes directly to the currents plus the momentum lost from wave dissipation. Additional sensitivity studies are performed to assess the potential contribution of windage on the Lagrangian model performance. Wave-induced drift is found to significantly affect the particle transport in the upper ocean. The skill of particle transport simulations depends on wave–ocean circulation interaction processes. The model simulations were assessed using drifter and high-frequency (HF) radar observations. The analysis of the model reveals that Eulerian currents produced by introducing wave-induced parameterization into the ocean model are essential for improving particle transport simulations. The results show that coupled wave–circulation models may improve transport simulations of marine litter, oil spills, larval drift or transport of biological materials.
    Type of Medium: Online Resource
    ISSN: 2073-4441
    Language: English
    Publisher: MDPI AG
    Publication Date: 2021
    detail.hit.zdb_id: 2521238-2
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  • 4
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-3-24)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-3-24)
    Abstract: Deep-sea sponges inhabit multiple areas of the deep North Atlantic at depths below 250 m. Living in the deep ocean, where environmental properties below the permanent thermocline generally change slowly, they may not easily acclimatize to abrupt changes in the environment. Until now consistent monitoring timeseries of the environment at deep sea sponge habitats are missing. Therefore, long-term simulation with coupled bio-physical models can shed light on the changes in environmental conditions sponges are exposed to. To investigate the variability of North Atlantic sponge habitats for the past half century, the deep-sea conditions have been simulated with a 67-year model hindcast from 1948 to 2014. The hindcast was generated using the ocean general circulation model HYCOM, coupled to the biogeochemical model ECOSMO. The model was validated at known sponge habitats with available observations of hydrography and nutrients from the deep ocean to evaluate the biases, errors, and drift in the model. Knowing the biases and uncertainties we proceed to study the longer-term (monthly to multi-decadal) environmental variability at selected sponge habitats in the North Atlantic and Arctic Ocean. On these timescales, these deep sponge habitats generally exhibit small variability in the water-mass properties. Three of the sponge habitats, the Flemish Cap, East Greenland Shelf and North Norwegian Shelf, had fluctuations of temperature and salinity in 4–6 year periods that indicate the dominance of different water masses during these periods. The fourth sponge habitat, the Reykjanes Ridge, showed a gradual warming of about 0.4°C over the simulation period. The flux of organic matter to the sea floor had a large interannual variability, that, compared to the 67-year mean, was larger than the variability of primary production in the surface waters. Lateral circulation is therefore likely an important control mechanism for the influx of organic material to the sponge habitats. Simulated oxygen varies interannually by less than 1.5 ml/l and none of the sponge habitats studied had oxygen concentrations below hypoxic levels. The present study establishes a baseline for the recent past deep conditions that future changes in deep sea conditions from observations and climate models can be evaluated against.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 5
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 8 ( 2022-1-25)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 8 ( 2022-1-25)
    Abstract: The Barents Sea is a key region in the Earth System and is home to highly productive marine resources. An integrated approach for strategic sustainable management of marine resources in such shelf-sea marine ecosystems requires, among many other aspects, a robust understanding of the impact of climate on local oceanic conditions. Here, using a combined observational and modelling approach, we show that decadal climatic trends associated with the North Atlantic Subpolar Gyre (SPG), within the period 1960–2019, have an impact on oceanic conditions in the Barents Sea. We relate hydrographic conditions in the Barents Sea to the decadal variability of the SPG through its impact on the Atlantic Inflow via the Faroe-Shetland Channel and the Barents Sea Opening. When the SPG warms, an increase in the throughput of subtropical waters across the Greenland-Scotland Ridge is followed by an increase in the volume of Atlantic Water entering the Barents Sea. These changes are reflected in pronounced decadal trends in the sea-ice concentration and primary production in the Barents Sea, which follow the SPG after an advective delay of 4–5 years. This impact of the SPG on sea-ice and primary production provides a dynamical explanation of the recently reported 7-year lagged statistical relationship between SPG and cod ( Gadus morhua ) biomass in the Barents Sea. Overall, these results highlight a potential for decadal ecosystem predictions in the Barents Sea.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 6
    Online Resource
    Online Resource
    Frontiers Media SA ; 2022
    In:  Frontiers in Marine Science Vol. 9 ( 2022-2-3)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 9 ( 2022-2-3)
    Abstract: The potential impact of offshore wind farms through decreasing sea surface wind speed on the shear forcing and its consequences for the ocean dynamics are investigated. Based on the unstructured-grid model SCHISM, we present a new cross-scale hydrodynamic model setup for the southern North Sea, which enables high-resolution analysis of offshore wind farms in the marine environment. We introduce an observational-based empirical approach to parameterize the atmospheric wakes in a hydrodynamic model and simulate the seasonal cycle of the summer stratification in consideration of the recent state of wind farm development in the southern North Sea. The simulations show the emergence of large-scale attenuation in the wind forcing and associated alterations in the local hydro- and thermodynamics. The wake effects lead to unanticipated spatial variability in the mean horizontal currents and to the formation of large-scale dipoles in the sea surface elevation. Induced changes in the vertical and lateral flow are sufficiently strong to influence the residual currents and entail alterations of the temperature and salinity distribution in areas of wind farm operation. Ultimately, the dipole-related processes affect the stratification development in the southern North Sea and indicate potential impact on marine ecosystem processes. In the German Bight, in particular, we observe large-scale structural change in stratification strength, which eventually enhances the stratification during the decline of the summer stratification toward autumn.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2022
    detail.hit.zdb_id: 2757748-X
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  • 7
    In: Marine Geology, Elsevier BV, Vol. 432 ( 2021-02), p. 106402-
    Type of Medium: Online Resource
    ISSN: 0025-3227
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1500648-7
    detail.hit.zdb_id: 2181-7
    SSG: 13
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  • 8
    Online Resource
    Online Resource
    Elsevier BV ; 2021
    In:  Marine Geology Vol. 438 ( 2021-08), p. 106523-
    In: Marine Geology, Elsevier BV, Vol. 438 ( 2021-08), p. 106523-
    Type of Medium: Online Resource
    ISSN: 0025-3227
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2021
    detail.hit.zdb_id: 1500648-7
    detail.hit.zdb_id: 2181-7
    SSG: 13
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  • 9
    Online Resource
    Online Resource
    Frontiers Media SA ; 2023
    In:  Frontiers in Marine Science Vol. 10 ( 2023-7-10)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 10 ( 2023-7-10)
    Abstract: High biological productivity and the efficient export of carbon-enriched subsurface waters to the open ocean via the continental shelf pump mechanism make mid-latitude continental shelves like the northwest European shelf (NWES) significant sinks for atmospheric CO 2 . Tidal forcing, as one of the regionally dominant physical forcing mechanisms, regulates the mixing-stratification status of the water column that acts as a major control for biological productivity on the NWES. Because of the complexity of the shelf system and the spatial heterogeneity of tidal impacts, there still are large knowledge gaps on the role of tides for the magnitude and variability of biological carbon fixation on the NWES. In our study, we utilize the flexible cross-scale modeling capabilities of the novel coupled hydrodynamic–biogeochemical modeling system SCHISM–ECOSMO to quantify the tidal impacts on primary production on the NWES. We assess the impact of both the barotropic tide and the kilometrical-scale internal tide field explicitly resolved in this study by comparing simulated hindcasts with and without tidal forcing. Our results suggest that tidal forcing increases biological productivity on the NWES and that around 16% (14.47 Mt C) of annual mean primary production on the shelf is related to tidal forcing. Vertical mixing of nutrients by the barotropic tide particularly invigorates primary production in tidal frontal regions, whereas resuspension and mixing of particulate organic matter by tides locally hinders primary production in shallow permanently mixed regions. The tidal impact on primary production is generally low in deep central and outer shelf areas except for the southwestern Celtic Sea, where tidal forcing substantially increases annual mean primary production by 25% (1.53 Mt C). Tide-generated vertical mixing of nutrients across the pycnocline, largely attributed to the internal tide field, explains one-fifth of the tidal response of summer NPP in the southwestern Celtic Sea. Our results therefore suggest that the tidal NPP response in the southwestern Celtic Sea is caused by a combination of processes likely including tide-induced lateral on-shelf transport of nutrients. The tidally enhanced turbulent mixing of nutrients fuels new production in the seasonally stratified parts of the NWES, which may impact the air–sea CO 2 exchange on the shelf.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2757748-X
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  • 10
    Online Resource
    Online Resource
    Frontiers Media SA ; 2023
    In:  Frontiers in Marine Science Vol. 10 ( 2023-2-1)
    In: Frontiers in Marine Science, Frontiers Media SA, Vol. 10 ( 2023-2-1)
    Abstract: The Pearl River Delta (PRD), where several megacities are located, has undergone drastic morphological changes caused by anthropogenic impact during the past few decades. In its main estuary, the water area has been reduced by 21% whilst the average water depth has increased by 2.24 m from 1970s to 2010s. The mainly human-induced morphological change together with sea level rise has jointly led to a remarkable change in the water stratification. However, the spatial and temporal variability of stratification in the estuary and associated driving mechanisms remain less understood. In this study, stratification in the Pearl River Estuary (PRE) in response to morphological change and external forcing is investigated by 3-dimensional numerical modeling. Simulation results indicate that stratification in the PRE exhibits distinct spatial and temporal variabilities. At a tidal-to-monthly time scale, variation of stratification is mainly driven by advection and straining through tidal forcing. At a monthly-to-seasonal scale, monsoon-driven river runoff and associated plume and fronts dominate the variation of stratification. Human-induced morphological change leads to an enhancement of stratification by up to four times in the PRE. Compared to an overwhelming human impact in the past few decades, future sea level rise would further enhance stratification, but to a much lesser extent than past human impacts. In addition, stratification in different areas of the estuary also responds differently to the driving factors. The western shoal of the estuary is most sensitive to changes in morphology and sea level due to its shallowness, followed by the channels and other parts of the estuary, which are less sensitive.
    Type of Medium: Online Resource
    ISSN: 2296-7745
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2023
    detail.hit.zdb_id: 2757748-X
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