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Arctic Ocean response to Greenland Sea wind anomalies in a suite of model simulations (2019)

Morven Muilwijk, Mehmet Ilicak, Sam B. Cornish, Sergey Danilov, Renske Gelderloos, Rüdiger Gerdes, Verena Haid, Thomas W.N. Haine, Helen L. Johnson, Yavor Kostov, Tamás Kovács, Camille Lique, Juliana M. Marson, Paul G. Myers, Jeffery Scot

Wiley

In: Journal of Geophysical Research: Oceans

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Publikationsdatum: 2019

Beschreibung: Abstract Multi‐model Arctic Ocean ``Climate Response Function” (CRF) experiments are analyzed in order to explore the effects of anomalous wind forcing over the Greenland Sea (GS) on poleward ocean heat transport, Atlantic Water (AW) pathways, and the extent of Arctic sea ice. Particular emphasis is placed on the sensitivity of the AW circulation to anomalously strong or weak GS winds in relation to natural variability, the latter manifested as part of the North Atlantic Oscillation (NAO). We find that anomalously strong (weak) GS wind forcing, comparable in strength to a strong positive (negative) NAO index, results in an intensification (weakening) of the poleward AW flow, extending from south of the North Atlantic Subpolar Gyre, through the Nordic Seas, and all the way into the Canadian Basin. Reconstructions made utilizing the calculated CRFs explain ~50 % of the simulated AW flow variance; this is the proportion of variability that can be explained by GS wind forcing. In the Barents and Kara Seas there is a clear relationship between the wind‐driven anomalous AW inflow and the sea ice extent. Most of the anomalous AW heat is lost to the atmosphere, and loss of sea ice in the Barents Sea results in even more heat loss to the atmosphere, and thus effective ocean cooling. Release of passive tracers in a subset of the suite of models reveals differences in circulation patterns and shows that the flow of AW in the Arctic Ocean is highly dependent on the wind stress in the Nordic Seas.

Print ISSN: 2169-9275

Digitale ISSN: 2169-9291

Thema: Geologie und Paläontologie , Physik

Publiziert von Wiley im Namen von American Geophysical Union (AGU).

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IJERPH, Vol. 16, Pages 3399: Leg Dominance as a Risk Factor for Lower-Limb Injuries in Downhill Skiers—A Pilot Study into Possible Mechanisms (2019)

Arunee Promsri, Alessia Longo, Thomas Haid, Aude-Clémence M. Doix, Peter Federolf

MDPI

In: International Journal of Environmental Research and Public Health

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Publikationsdatum: 2019

Beschreibung: Leg dominance has been reported as one potential risk factor for lower-limb injuries in recreational downhill skiers. The current study proposed and tested two possible mechanisms for a leg dominance effect on skiing injuries—imbalance of the knee muscle strength and bilateral asymmetry in sensorimotor control. We hypothesized that the knee muscle strength (Hypothesis 1; H1) or postural control (Hypothesis 2; H2) would be affected by leg dominance. Fifteen well-experienced recreational downhill skiers (aged 24.3 ± 3.2 years) participated in this study. Isometric knee flexor/extensor muscle strength was tested using a dynamometer. Postural control was explored by using a kinematic principal component analysis (PCA) to determine the coordination structure and control of three-dimensional unipedal balancing movements while wearing ski equipment on firm and soft standing surfaces. Only H2 was supported when balancing on the firm surface, revealing that when shifting body weight over the nondominant leg, skiers significantly changed the coordination structure (p 〈 0.006) and the control (p 〈 0.004) of the lifted-leg movements. Based on the current findings, bilateral asymmetry in sensorimotor control rather than asymmetry in strength seems a more likely mechanism for the previously reported effect of leg dominance on lower-limb injury risk in recreational downhill skiers.

Print ISSN: 1661-7827

Digitale ISSN: 1660-4601

Thema: Energietechnik , Medizin

Publiziert von MDPI

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Entropy, Vol. 21, Pages 614: Changed Temporal Structure of Neuromuscular Control, Rather Than Changed Intersegment Coordination, Explains Altered Stabilographic Regularity after a Moderate Perturbation of the Postural Control System (2019)

Felix Wachholz, Tove Kockum, Thomas Haid, Peter Federolf

MDPI

In: Entropy

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Publikationsdatum: 2019

Beschreibung: Sample entropy (SaEn) applied on center-of-pressure (COP) data provides a measure for the regularity of human postural control. Two mechanisms could contribute to altered COP regularity: first, an altered temporal structure (temporal regularity) of postural movements (H1); or second, altered coordination between segment movements (coordinative complexity; H2). The current study used rapid, voluntary head-shaking to perturb the postural control system, thus producing changes in COP regularity, to then assess the two hypotheses. Sixteen healthy participants (age 26.5 ± 3.5; seven females), whose postural movements were tracked via 39 reflective markers, performed trials in which they first stood quietly on a force plate for 30 s, then shook their head for 10 s, finally stood quietly for another 90 s. A principal component analysis (PCA) performed on the kinematic data extracted the main postural movement components. Temporal regularity was determined by calculating SaEn on the time series of these movement components. Coordinative complexity was determined by assessing the relative explained variance of the first five components. H1 was supported, but H2 was not. These results suggest that moderate perturbations of the postural control system produce altered temporal structures of the main postural movement components, but do not necessarily change the coordinative structure of intersegment movements.

Digitale ISSN: 1099-4300

Thema: Chemie und Pharmazie , Physik

Publiziert von MDPI

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Agronomy, Vol. 9, Pages 214: Effect of Salinity and Water Stress on the Essential Oil Components of Rosemary (Rosmarinus officinalis L.) (2019)

Radhia Sarmoum, Soumia Haid, Mohamed Biche, Zahreddine Djazouli, Bachar Zebib, Othmane Merah

MDPI

In: Agronomy

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Publikationsdatum: 2019

Beschreibung: The effect of salinity and water stresses on the essential oil components of Rosmarinus officinalis essential oil was investigated. Rosemary plants were submitted to different water treatments: tap water (TW), salt water (SW) and without irrigation (NIR). GC/MS analysis showed that ten and eleven volatile compounds were identified in essential oil of rosemary plants irrigated with tap water (TW) and salt water (SW), respectively. However, thirteen volatile compounds were identified in essential oil of non-irrigated plants (NIR). Moreover, among these compounds, α-Pinene, Eucalyptol (1,8 Cineol), Camphene, Borneol, D-verbenone, Bornyl acetate were the major components of oil. Also, GC/MS results highlighted that non-irrigated rosemary plants showed the highest essential oil yield (Y). Obtained oil yields followed the order YNIR 〉 YTW 〉 YSW. In conclusion, qualitative and quantitative differences in rosemary essential oil components were highlighted in relation to water stress.

Digitale ISSN: 2073-4395

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Wirtschaftswissenschaften

Publiziert von MDPI

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Entropy, Vol. 21, Pages 70: The Effect of Cognitive Resource Competition Due to Dual-Tasking on the Irregularity and Control of Postural Movement Components (2019)

Thomas Haid, Peter Federolf

MDPI

In: Entropy

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Publikationsdatum: 2019

Beschreibung: Postural control research suggests a non-linear, n-shaped relationship between dual-tasking and postural stability. Nevertheless, the extent of this relationship remains unclear. Since kinematic principal component analysis has offered novel approaches to study the control of movement components (PM) and n-shapes have been found in measures of sway irregularity, we hypothesized (H1) that the irregularity of PMs and their respective control, and the control tightness will display the n-shape. Furthermore, according to the minimal intervention principle (H2) different PMs should be affected differently. Finally, (H3) we expected stronger dual-tasking effects in the older population, due to limited cognitive resources. We measured the kinematics of forty-one healthy volunteers (23 aged 26 ± 3; 18 aged 59 ± 4) performing 80 s tandem stances in five conditions (single-task and auditory n-back task; n = 1–4), and computed sample entropies on PM time-series and two novel measures of control tightness. In the PM most critical for stability, the control tightness decreased steadily, and in contrast to H3, decreased further for the younger group. Nevertheless, we found n-shapes in most variables with differing magnitudes, supporting H1 and H2. These results suggest that the control tightness might deteriorate steadily with increased cognitive load in critical movements despite the otherwise eminent n-shaped relationship.

Digitale ISSN: 1099-4300

Thema: Chemie und Pharmazie , Physik

Publiziert von MDPI

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Simulated heat flux and sea ice production at coastal polynyas in the southwestern Weddell Sea (2013)

V. Haid, R. Timmermann

Wiley

In: Journal of Geophysical Research JGR - Oceans

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Publikationsdatum: 2013-03-19

Beschreibung: [1] Coastal polynyas are areas in an ice-covered ocean where the ice cover is exported, mostly by off-shore winds. The resulting reduction of sea ice enables an enhanced ocean–atmosphere heat transfer. Once the water temperatures are at the freezing point, further heat loss induces sea ice production. The heat exchange and ice production in coastal polynyas in the southwestern Weddell Sea is addressed using the Finite-Element Sea-ice Ocean Model, a primitive-equation, hydrostatic ocean circulation model coupled with a dynamicthermodynamic sea-ice model, which allows to quantify the amount of heat associated with cooling of the water column. Three important polynya regions are identified: at Brunt Ice Shelf, at Ronne Ice Shelf and along the southern part of the Antarctic Peninsula. Multiyear winter means (May-September 1990–2009) give an upward heat flux to the atmosphere of 311 W/m 2 in the Brunt polynyas, 511 W/m 2 in Ronne Polynya and 364 W/m 2 in the Antarctic Peninsula polynyas, whereof 57 W/m 2 , 49 W/m 2 and 48 W/m 2 , respectively, are supplied as oceanic heat flux from deeper layers. The mean winter sea ice production is 7.2 cm/d in the Brunt polynyas corresponding to an ice volume of 1.3 · 10 10 m 3 /winter, 13.2 cm/d at Ronne polynya (4.4 · 10 10 m 3 /winter), and 9.2 cm/d in the Antarctic Peninsula polynyas (2.1 · 10 10 m 3 /winter. The heat flux to the atmosphere inside polynyas is 7 to 9 times higher than the heat flux in the adjacent area; polynya ice production per unit area exceeds adjacent values by a factor of 9 to 14.

Print ISSN: 0148-0227

Thema: Geologie und Paläontologie , Physik

Publiziert von Wiley im Namen von American Geophysical Union (AGU).

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Sea ice motion and open water area at the Ronne Polynia, Antarctica: SAR observations vs. model results (2013)

T. Hollands, V. Haid, W. Dierking, R. Timmermann, L. Ebner

Wiley

In: Journal of Geophysical Research JGR - Oceans

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Publikationsdatum: 2013-03-14

Beschreibung: [1] This study deals with observations and simulations of the evolution of coastal polynias focusing on the Ronne Polynia. We compare differences in polynia extent and ice drift patterns derived from satellite radar images and from simulations with the Finite Element Sea ice Ocean Model (FESOM), employing three atmospheric forcing data sets that differ in spatial and temporal resolution. Two polynia events are analysed, one from austral summer and one from late fall 2008. The open water area in the polynia is of similar size in the satellite images and in the model simulations, but its temporal evolution differs depending on katabatic winds being resolved in the atmospheric forcing data sets. Modelled ice drift is slower than the observed and reveals greater turning angles relative to the wind direction in many cases. For the summer event, model results obtained with high-resolution forcing are closer to the drift field derived from radar imagery than those from coarse-resolution forcing. For the late-fall event, none of the forcing data yields outstanding results. Our study demonstrates that a dense (1-3 km) model grid and atmospheric forcing provided at high spatial resolution (〈50 km) are critical to correctly simulate coastal polynias with a coupled sea-ice ocean model.

Print ISSN: 0148-0227

Thema: Geologie und Paläontologie , Physik

Publiziert von Wiley im Namen von American Geophysical Union (AGU).

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CROSSINN - a field experiment to study the three-dimensional flow structure in the Inn Valley, Austria (2020)

Adler, Bianca ; Gohm, Alexander ; Kalthoff, Norbert ; [weitere]

American Meteorological Society

In: Bulletin of the American Meteorological Society. 2020; 1-55. Published 2020 Sep 18. doi: 10.1175/bams-d-19-0283.1. [early online release]

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Publikationsdatum: 2020-09-18

Beschreibung: Capsule Summary The CROSSINN field experiment investigates the three-dimensional structure of thermally and dynamically driven flows and their impact on the boundary layer in a large Alpine valley using comprehensive state-of-the-art instrumentation.

Print ISSN: 0003-0007

Digitale ISSN: 1520-0477

Thema: Geographie , Physik

Publiziert von American Meteorological Society

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Foehn–cold pool interactions in the Inn Valley during PIANO IOP2 (2020)

Haid, M. ; Gohm, A. ; Umek, L. ; [weitere]

Wiley

In: Quarterly Journal of the Royal Meteorological Society. 2020; 146(728): 1232-1263. Published 2020 Jan 29. doi: 10.1002/qj.3735.

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Publikationsdatum: 2020-01-29

Print ISSN: 0035-9009

Digitale ISSN: 1477-870X

Thema: Geographie , Physik

Publiziert von Wiley

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Studying Urban Climate and Air Quality in the Alps: The Innsbruck Atmospheric Observatory (2020)

Karl, Thomas ; Gohm, Alexander ; Rotach, Mathias W. ; [weitere]

American Meteorological Society

In: Bulletin of the American Meteorological Society. 2020; 101(4): E488-E507. Published 2020 Apr 01. doi: 10.1175/bams-d-19-0270.1.

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Publikationsdatum: 2020-04-01

Beschreibung: The Innsbruck Atmospheric Observatory (IAO) aims to investigate atmospheric chemistry, micrometeorology, and mountain meteorology in a synergistic fashion within an urban setting. A new measurement supersite has been established in order to study processes affecting the exchange of momentum, energy, trace gases, and aerosols in an Alpine urban environment. Various long-term continuous measurements are augmented by frequent focused research campaigns with state-of-the-art instrumentation, linking different classes of data and addressing significant gaps in scientific data availability for urban environments. Current activities seek to address research objectives related to the urban heat island, trace gas emissions, the influence of foehn on air quality, and the atmospheric distribution of trace gases and aerosols in a mountainous city. We present initial results from long-term operations and first highlights from two intensive operational phases, showing that 1) the exchange of greenhouse gas emissions is dominated by anthropogenic activities and is driven by location-specific venting of street canyon air; 2) foehn events significantly perturb the photostationary state indicative for an extensive and rapid airmass exchange of the valley atmosphere; 3) the temporal distribution of pollutants is often decoupled from their emissions and primarily modulated by mountain boundary layer dynamics; 4) we can detect a large number of volatile chemical products in the urban atmosphere, which can be used to fingerprint anthropogenic emission sources; and 5) the first urban carbonyl sulfide (COS) flux measurements point toward anthropogenic emission sources.

Print ISSN: 0003-0007

Digitale ISSN: 1520-0477

Thema: Geographie , Physik

Publiziert von American Meteorological Society

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