Links between atmospheric cloud radiative effects and tropical circulations

2021 Spring.Includes bibliographical references.Atmospheric cloud radiative effects (ACRE) quantify the radiative heating or cooling due to clouds within the atmosphere. In this study, a framework is developed with which to analyze the ways that ACRE impact large-scale circulations in humid and dry regions of the tropics. The frame-work is applied to a set of simulations from a global atmospheric model configured with uniform tropical sea surface temperatures, following the protocol of the Radiative Convective Equilibrium Model Intercomparison Project. It is found that humid regions export energy and import moisture, and that ACRE in extremely humid regions are strong enough to change the sign of the net radiation tendency. This net heating drives a feedback in which large-scale ascent moistens the troposphere by lifting latent energy from near the surface. Moisture at these higher levels then forms clouds which in turn reinforce the ACRE, continuing the process. The relevance of this feedback to the germinal study of Riehl and Malkus (1958) is discussed. Additionally, the analysis method reveals a simple relationship between cloud radiative effects and column relative humidity in the idealized model. The same relationship is also observed in cloud radiative effects calculated from satellite observations. This suggests a simple way to estimate the cloud radiative effect at the top of the atmosphere. The estimated cloud radiative effect may be useful in estimating the ACRE, which is harder to infer from measurements using previous methods. The estimation shows some skill at estimating the cloud radiative effect in humid regions across the tropics on time scales of one month or longer. The method is found to be extremely effective at estimating observed cloud radiative effects in the equatorial west Pacific. Weaknesses of the estimation method in relation to marine stratus clouds are discussed

MARKERLESS MOTION CAPTURE WITHIN SPORT: AN EXPLORATORY CASE STUDY

The purpose of this case study was to compare centre of mass (CoM) recorded by a markerless motion capture system (60 Hz) to a criterion marker based system (120 Hz). Gait kinematics of one healthy male participant was recorded five times by both capture systems simultaneously. CoM position was assessed using a full body six degrees of freedom model, normalised to the stance phase based on a 20 N vertical force threshold recorded with force plates. T-tests on RMSE indicated frontal (0.002 m) and sagittal (0.066 m) CoM coordinates were not significantly different between systems, transverse CoM (0.020 m) was significantly different. Statistical parametric mapping showed significant difference in sagittal CoM during the last 20% of stance. Markerless systems show promise in accurately assessing CoM. Future work should focus on sport actions with larger cohorts

LOWER LIMB ASYMMETRY DURING THE SKELETON PUSH START

The aim of this study was to identify the presence and performance implication of asymmetry within the skeleton push start. Motion data were captured on 13 international skeleton athletes, using a custom 9-camera computer vision system. 6 maximal effort pushes were captured allowing the reconstruction of a 0–15 m push. Intra-limb differences for spatiotemporal variables and the change in velocity (ΔV) across a step were analysed. A negative relationship existed between 5 – 15 m split time and ΔV across a stride. Athletes who maximise their velocity across a stride were more likely to perform well in the skeleton push start. Though athletes employed different strategies based on inside and outside leg ΔV to achieve their performance outcome

Resilience, alexithymia, and university stress in relation to anxiety and problematic alcohol use among female university students

Objectives University students in Australia report higher levels of stress than non‐students of the same age, with females reporting higher stress than males. The ability to successfully adapt to, and cope with, stressful situations and events, often referred to as resilience, requires social and interpersonal resources as well as the ability to effectively self‐regulate emotions. When such resources and abilities are deficient, responses to university stress are likely to be maladaptive. Deficient emotional self‐regulation is characteristic of individuals with the subclinical personality trait alexithymia, who also tend to suffer from social and interpersonal difficulties; thus students with alexithymia may be especially susceptible to university stress and associated adverse outcomes of low resilience. The present study examined resilience in relation to alexithymia, university stress, and two common outcomes of the latter in female university students: anxiety and problematic drinking. Method Validated self‐report measures of the relevant constructs were completed online by 136 female university students from two Australian universities. All participants indicated they had English‐language proficiency and no history of serious head injury or diagnosed psychological disorder. Results Serial mediation models indicated that resilience showed the predicted protective relationship to both problematic drinking and anxiety through lower levels of alexithymia and university stress. Conclusions Findings suggest that students who lack resilience are more likely to report stress at university, as well as associated adverse outcomes such as anxiety and problematic drinking, due to deficiencies in emotional self‐regulation and inadequate use of social and interpersonal resources for successful coping

Intertidal habitat mapping for ecosystem goods and services: Tairua harbour

In January 2013, Waikato Regional Council (WRC) contracted the National Institute of Water and Atmospheric Research (NIWA), to develop rapid assessment techniques for mapping of intertidal habitats associated with the provision of ecosystem goods and services. Ecosystem goods and services are defined as ‘the direct and indirect benefits that humankind receives or values from natural or semi-natural habitats’ and include the provision of food and raw materials, waste treatment, processing and storage, disturbance prevention, sediment retention, water filtration and regulation, nutrient regulation, gas and climate regulation, habitat structure and cultural services such as spiritual heritage and leisure and recreation (Townsend et al. 2010). Assessment techniques were to be trialled and implemented for the intertidal area of the Tairua estuary with the view of providing: • Descriptions of habitat types that may be linked to levels of ecosystem goods and services. • Descriptions of the techniques involved in differentiating and mapping habitats, and an analysis of the precision and accuracy/validity of the methods. This report documents the evolution of the methodology and a proof of concept using Tairua estuary as a test case to build a habitat map. The goal is to generate precursor maps that will facilitate the mapping of ecosystem goods and services in the near future

A Wasserstein-type Distance for Gaussian Mixtures on Vector Bundles with Applications to Shape Analysis

This paper uses sample data to study the problem of comparing populations on finite-dimensional parallelizable Riemannian manifolds and more general trivial vector bundles. Utilizing triviality, our framework represents populations as mixtures of Gaussians on vector bundles and estimates the population parameters using a mode-based clustering algorithm. We derive a Wasserstein-type metric between Gaussian mixtures, adapted to the manifold geometry, in order to compare estimated distributions. Our contributions include an identifiability result for Gaussian mixtures on manifold domains and a convenient characterization of optimal couplings of Gaussian mixtures under the derived metric. We demonstrate these tools on some example domains, including the pre-shape space of planar closed curves, with applications to the shape space of triangles and populations of nanoparticles. In the nanoparticle application, we consider a sequence of populations of particle shapes arising from a manufacturing process, and utilize the Wasserstein-type distance to perform change-point detection

Topological Optimal Transport for Geometric Cycle Matching

Topological data analysis is a powerful tool for describing topological signatures in real world data. An important challenge in topological data analysis is matching significant topological signals across distinct systems. In geometry and probability theory, optimal transport formalises notions of distance and matchings between distributions and structured objects. We propose to combine these approaches, constructing a mathematical framework for optimal transport-based matchings of topological features. Building upon recent advances in the domains of persistent homology and optimal transport for hypergraphs, we develop a transport-based methodology for topological data processing. We define measure topological networks, which integrate both geometric and topological information about a system, introduce a distance on the space of these objects, and study its metric properties, showing that it induces a geodesic metric space of non-negative curvature. The resulting Topological Optimal Transport (TpOT) framework provides a transport model on point clouds that minimises topological distortion while simultaneously yielding a geometrically informed matching between persistent homology cycles.Comment: Comments are welcome