Ian R. Young

Bio: Ian R. Young is an academic researcher from University of Melbourne. The author has contributed to research in topics: Wind wave & Wind speed. The author has an hindex of 50, co-authored 162 publications receiving 8795 citations. Previous affiliations of Ian R. Young include University of Adelaide & Australian National University.

Global Trends in Wind Speed and Wave Height

Abstract: Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

Global trends in wind speed and wave height over the past 25 years

Abstract: Wind speeds over the world’s oceans have increased over the past two decades, as have wave heights. Studies of climate change typically consider measurements or predictions of temperature over extended periods of time. Climate, however, is much more than temperature. Over the oceans, changes in wind speed and the surface gravity waves generated by such winds play an important role. We used a 23-year database of calibrated and validated satellite altimeter measurements to investigate global changes in oceanic wind speed and wave height over this period. We find a general global trend of increasing values of wind speed and, to a lesser degree, wave height, over this period. The rate of increase is greater for extreme events as compared to the mean condition.

A three-dimensional analysis of marine radar images for the determination of ocean wave directionality and surface currents

Abstract: A series of spatial wave images recorded by a conventional marine radar is analyzed to determine the three-dimensional E(kx, ky, ω) spectrum. In the absence of a surface current the spectral energy in this three-dimensional wave number frequency space will lie on a shell defined by the dispersion relationship. Any deviation from the expected dispersion relationship can be interpreted as being due to a current induced Doppler shift of the wave frequency. A least squares curve fitting technique is used to determine the surface current required to account for the observed Doppler shift. A comparison of the radar determined spectra and surface currents with ground truth data indicates that the radar system and analysis technique produces results consistent with conventional instrumentation.

Wind Generated Ocean Waves

Abstract: Part 1 Wave theory: introduction small amplitude or linear theory wave transformation limitations of linear wave theory. Part 2 Stochastic properties of ocean waves: introduction probability distribution of wave heights global distribution of wave properties limitations of global statistics. Part 3 Physical mechanisms of wave evolution: introduction radiative transfer equation atmospheric input, Sin* nonlinear quadruplet interactions, Sni* white-cap dissipation, Sds* the spectral balance. Part 4 Fetch and duration limited growth: introduction similarity theory and dimensionless scaling growth curves for energy and peak frequency one-dimensional spectrum directional spreading. Part 5 Non-stationary wind fields: introduction the interaction of swell and wind sea rapid change in wind speed rapid change in wind direction hurricane wind and wave fields. Part 6 Finite depth effects: introduction physical processes finite depth growth curves finite depth one-dimensional spectra finite depth directional spreading. Part 7 Numerical modelling of waves: introduction phase resolving models phase averaging models source term representation computational aspects the WAM model data assimilation. Part 8 Ocean wave measurement: introduction "in situ" methods data analysis remote sensing techniques.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

A third-generation wave model for coastal regions: 1. Model description and validation

Abstract: A third-generation numerical wave model to compute random, short-crested waves in coastal regions with shallow water and ambient currents (Simulating Waves Nearshore (SWAN)) has been developed, implemented, and validated. The model is based on a Eulerian formulation of the discrete spectral balance of action density that accounts for refractive propagation over arbitrary bathymetry and current fields. It is driven by boundary conditions and local winds. As in other third-generation wave models, the processes of wind generation, whitecapping, quadruplet wave-wave interactions, and bottom dissipation are represented explicitly. In SWAN, triad wave-wave interactions and depth-induced wave breaking are added. In contrast to other third-generation wave models, the numerical propagation scheme is implicit, which implies that the computations are more economic in shallow water. The model results agree well with analytical solutions, laboratory observations, and (generalized) field observations.

The role of coastal plant communities for climate change mitigation and adaptation

Abstract: Marine vegetated habitats occupy a small fraction of the ocean surface, but contribute about 50% of the carbon that is buried in marine sediments. In this Review the potential benefits of conservation, restoration and use of these habitats for coastal protection and climate change mitigation are assessed. Marine vegetated habitats (seagrasses, salt-marshes, macroalgae and mangroves) occupy 0.2% of the ocean surface, but contribute 50% of carbon burial in marine sediments. Their canopies dissipate wave energy and high burial rates raise the seafloor, buffering the impacts of rising sea level and wave action that are associated with climate change. The loss of a third of the global cover of these ecosystems involves a loss of CO2 sinks and the emission of 1 Pg CO2 annually. The conservation, restoration and use of vegetated coastal habitats in eco-engineering solutions for coastal protection provide a promising strategy, delivering significant capacity for climate change mitigation and adaption.

Antarctic ice-sheet loss driven by basal melting of ice shelves

Abstract: Using satellite laser altimetry, basal melting of ice shelves is determined to be the main driver of Antarctic ice-sheet loss,with changing climate the likely cause. Ice shelves — those parts of the ice sheets that extend over the ocean — are known to provide a buttressing effect that limits the velocity of upstream glaciers and ice streams. In Antarctica, loss of ice shelves has already been implicated in the accelerated motion of some ice masses, but the extent of ice-shelf wasting remained unknown. Now, Pritchard et al. present a complete survey of Antarctic ice-shelf thinning between 2003 and 2008, and reveal loss rates of up to 7 metres per year. Much of the thinning is attributable to wind-driven movement of warm water through deep troughs crossing the continental shelf. The authors conclude that the thinning has led to loss of buttressing strength and accelerated loss of ice mass. Accurate prediction of global sea-level rise requires that we understand the cause of recent, widespread and intensifying1,2 glacier acceleration along Antarctic ice-sheet coastal margins3. Atmospheric and oceanic forcing have the potential to reduce the thickness and extent of floating ice shelves, potentially limiting their ability to buttress the flow of grounded tributary glaciers4. Indeed, recent ice-shelf collapse led to retreat and acceleration of several glaciers on the Antarctic Peninsula5. But the extent and magnitude of ice-shelf thickness change, the underlying causes of such change, and its link to glacier flow rate are so poorly understood that its future impact on the ice sheets cannot yet be predicted3. Here we use satellite laser altimetry and modelling of the surface firn layer to reveal the circum-Antarctic pattern of ice-shelf thinning through increased basal melt. We deduce that this increased melt is the primary control of Antarctic ice-sheet loss, through a reduction in buttressing of the adjacent ice sheet leading to accelerated glacier flow2. The highest thinning rates occur where warm water at depth can access thick ice shelves via submarine troughs crossing the continental shelf. Wind forcing could explain the dominant patterns of both basal melting and the surface melting and collapse of Antarctic ice shelves, through ocean upwelling in the Amundsen6 and Bellingshausen7 seas, and atmospheric warming on the Antarctic Peninsula8. This implies that climate forcing through changing winds influences Antarctic ice-sheet mass balance, and hence global sea level, on annual to decadal timescales.