Exploring the 4D scales of eco-geomorphic interactions along a river corridor using repeat UAV Laser Scanning (UAV-LS), multispectral imagery, and a functional traits framework

Vegetation plays a critical role in the modulation of fluvial process and morphological evolution. However, adequately capturing the spatial variability and complexity of vegetation characteristics remains a challenge. Currently, most of the research seeking to address these issues takes place at either the individual plant scale or via larger scale bulk classifications, with the former seeking to characterise vegetation-flow interactions and the latter identifying spatial variation in vegetation types. Herein, we devise a method which extracts functional vegetation traits using UAV laser scanning and multispectral imagery, and upscale these to reach scale guild classifications. Simultaneous monitoring of morphological change is undertaken to identify eco-geomorphic links between different guilds and the geomorphic response of the system in the context of long-term decadal changes. Identification of four guilds from quantitative structural modelling based on analysis of terrestrial and UAV based laser scanning and two further guilds from image analysis was achieved. These were upscaled to reach-scale guild classifications with an overall accuracy of 80 % and links to magnitudes of geomorphic activity explored. We show that different vegetation guilds have a role in influencing morphological change through the stabilisation of banks, but that limits on this influence are evident in the prior long-term analysis. This research reveals that remote sensing offers a solution to the difficulty of scaling traits-based approaches for eco-geomorphic research, and that these methods may be applied to larger areas using airborne laser scanning and satellite imagery datasets.

What makes a human? Conscious human beings are hyperobjects that interact via physical and mental representations in an ecosystem based on fundamental story-flow interactions.

What is a human being? Some might answer this question by referring to a biological body, growing from genetic information passed on through generations. Others refer to a mind, developed from infancy to adulthood, expressing itself self-aware and intelligently. Few will argue that a human being could exist without one or the other, but many disagree on their relative contribution. Does the conscious mind emerge solely from a single physical body? Is the developing body shaped purely by biological predetermination? I propose that the formation of individual human beings is subject to an environment that envelops both, the physical and mental realms. This environment is here referred to as story-verse of humanity. It is an ecosystem that emerged from biological activity but grew and evolved into an interactive space that includes temporal interactions, such as created by nervous system activity. The emerging story-verse gives rise to persistent hyperobjects, including individual human beings, whose stories perpetuate themselves via physical and mental representations. The story-verse is a real physics realm that includes the four fundamental interactions described by particle physics, but additionally requires higher-order fundamental forces that facilitate interactions between the physical and mental realm.

Towards a transient gravity wave parametrization in atmospheric models

<p>Subgrid-scale internal gravity waves (IGWs) are important distributors of energy in a stratified atmosphere. While they are mostly excited at lower altitudes their effects are most important between the upper troposphere to the mesopause (~85km). During propagation–both in the vertical and the horizontal–nonlinear IGWs can exert a wave drag on the mean winds, interact with the mean potential temperature, and mix atmospheric tracers such as aerosols or greenhouse gases.</p> <p>In state-of-the art weather prediction models IGWs are typically parametrized using the single-column and the steady-state assumptions. These parametrizations take into account dissipative effects of IGWs but neglect their horizontal propagation and all of their transient interaction mechanisms such as direct wave-mean-flow interactions. However, the latter have been shown to contribute to IGW dynamics in various idealized studies.</p> <p>Here we present advances of the use of the transient Multi Scale Gravity Wave Model (MS-GWaM) in the upper atmosphere model UA-ICON. Based on Lagrangian ray-tracing the parametrization includes various non-orographic wave sources, transient propagation in both the horizontal and vertical directions, direct wave-mean-flow interactions and wave breaking. The resulting setup satisfactorily reproduces the observed mean-wind and potential temperature climatology and already shows promising insights into the details of the role of IGWs in the atmosphere.</p>

Suppressed Thermocline Mixing in the Center of Anticyclonic Eddy in the North South China Sea

Direct microstructure observations and fine-scale measurements of an anticyclonic mesoscale eddy were conducted in the northern South China Sea in July 2020. An important finding was that suppressed turbulent mixing in the thermocline existed at the center of the eddy, with an averaged diapycnal diffusivity at least threefold smaller than the peripheral diffusivity. Despite the strong background shear and significant wave–mean flow interactions, the results indicated that the lack of internal wave energy in the corresponding neap tide period during measurement of the eddy’s center was the main reason for the suppressed turbulent mixing in the thermocline. The applicability of the fine-scale parameterization method in the presence of significant wave–mean flow interactions in a mesoscale eddy was evaluated. Overprediction via fine-scale parameterization occurred in the center of the eddy, where the internal waves were inactive; however, the parameterization results were consistent with microstructure observations along the eddy’s periphery, where active internal waves existed. This indicates that the strong background shear and wave–mean flow interactions affected by the mesoscale eddy were not the main contributing factors that affected the applicability of fine-scale parameterization in the northern South China Sea. Instead, our results showed that the activity of internal waves is the most important consideration.

Towards a numerical laboratory for investigations of gravity-wave mean-flow interactions in the atmosphere

Idealized integral studies of the dynamics of atmospheric inertia-gravity waves (IGWs) from their sources in the troposphere (e.g., by spontaneous emission from jets and fronts) to dissipation and mean-flow effects at higher altitudes could contribute to a better treatment of these processes in IGW parameterizations in numerical weather prediction and climate simulation. It seems important that numerical codes applied for this purpose are efficient and focus on the essentials. Therefore a previously published staggered-grid solver for f-plane soundproof pseudo-incompressible dynamics is extended here by two main components. These are 1) a semi-implicit time stepping scheme for the integration of buoyancy and Coriolis effects, and 2) the incorporation of Newtonian heating consistent with pseudo-incompressible dynamics. This heating function is used to enforce a temperature profile that is baroclinically unstable in the troposphere and it allows the background state to vary in time. Numerical experiments for several benchmarks are compared against a buoyancy/Coriolis-explicit third-order Runge-Kutta scheme, verifying the accuracy and efficiency of the scheme. Preliminary mesoscale simulations with baroclinic-wave activity in the troposphere show intensive small-scale wave activity at high altitudes, and they also indicate there the expected reversal of the zonal-mean-zonal winds.

Multiple airflow patterns in human microenvironment and the influence on short-distance airborne cross-infection – A review

The global spread of the coronavirus disease 2019 (COVID-19) has increased the demand of effective control of the disease transmission between people, especially when they are in close distance between each other. The microenvironment between the people in short distance contains multiple airflow patterns that directly affect the disease transmission. By understanding and respecting this special localized environment, the airborne cross-infection at both short and long distance can be minimized. This paper gives an overview of the flow fields in human microenvironment. The exhalation flow from different respiratory activities, e.g. normal breathing, speaking, coughing or sneezing is considered as a part of the microenvironment. The dynamics of the exhalation flow and the contained droplets or aerosols are summarized from previous studies. The factors influencing the flow fields in human microenvironment are discussed, including both the physiological factors of the occupants and the environmental factors in the ventilated context (macroenvironment). Effective control of these influencing factors can be helpful to mitigate airborne transmission risk between individuals. This paper highlights the importance of better understanding of the dynamics and transmission routes of the expelled virus-laden droplets or aerosols, which are largely affected by complex flow interactions in human microenvironment.