The influence of the stratospheric state on North Atlantic weather regimes

Stratosphere-troposphere coupling is often viewed from the perspective of the annular modes and their dynamics. Despite the obvious benefits of this approach, recent work has emphasised the greater tropospheric sensitivity to stratospheric variability in the Atlantic basin than in the Pacific basin. In this study, a new approach to understanding stratosphere-troposphere coupling is proposed, with a focus on the influence of the stratospheric state on North Atlantic weather regimes (during extended winter, November to March). The influence of the strength of the lower stratospheric vortex on four commonly used tropospheric weather regimes is quantified. The negative phase of the North Atlantic Oscillation is most sensitive to the stratospheric state, occurring on 33% of days following weak vortex conditions but on only 5% of days following strong vortex conditions. An opposite and slightly weaker sensitivity is found for the positive phase of the North Atlantic Oscillation and the Atlantic Ridge regime. For the North Atlantic Oscillation regimes, stratospheric conditions change both the probability of remaining in each regime and the probability of transitioning to that regime from others. A logistic regression model is developed to further quantify the sensitivity of tropospheric weather regimes to the lower stratospheric state. The logistic regression model predicts an increase of 40-60% in the probability of transition to the negative phase of the North Atlantic Oscillation for a one standard deviation reduction in the strength of the stratospheric vortex. Similarly it predicts a 10-30% increase in the probability of transition to the positive phase of the North Atlantic Oscillation for a one standard deviation increase in the strength of the stratospheric vortex. The stratosphere-troposphere coupling in the European Centre for Medium Range Weather Forecasts, Integrated Forecasting System model is found to be consistent with the re- analysis data by fitting the same logistic regression model

Passive, broadband and low-frequency suppression of laser amplitude noise to the shot-noise limit using hollow-core fibre

We use hollow-core fibre to preserve the spectrum and temporal profile of picosecond laser pulses in CBD to suppress 2.6 dB of amplitude noise at MHz noise frequencies, to within 0.01 dB of the shot-noise limit. We provide an enhanced version of the CBD scheme that concatenates circuits to suppress over multiple frequencies and over broad frequency ranges --- we perform a first demonstration that reduces total excess amplitude noise, between 2 - 6 MHz, by 85%. These demonstrations enable passive, broad-band, all-guided fibre laser technology operating at the shot-noise limit.Comment: 8 pages, 8 figure

Globally Guided Trajectory Planning in Dynamic Environments

Navigating mobile robots through environments shared with humans is challenging. From the perspective of the robot, humans are dynamic obstacles that must be avoided. These obstacles make the collision-free space nonconvex, which leads to two distinct passing behaviors per obstacle (passing left or right). For local planners, such as receding-horizon trajectory optimization, each behavior presents a local optimum in which the planner can get stuck. This may result in slow or unsafe motion even when a better plan exists. In this work, we identify trajectories for multiple locally optimal driving behaviors, by considering their topology. This identification is made consistent over successive iterations by propagating the topology information. The most suitable high-level trajectory guides a local optimization-based planner, resulting in fast and safe motion plans. We validate the proposed planner on a mobile robot in simulation and real-world experiments.Comment: 7 pages, 6 figures, accepted to IEEE International Conference on Robotics and Automation (ICRA) 202

First Steps in Air Quality for Built Environment Practitioners

Air pollution is the biggest environmental risk to health. Globally, nine out of ten people live in a city that does not comply with WHO air quality standards. Within the UK, poor outdoor air quality is linked to 50,000 deaths each year. The most vulnerable are children, the elderly, or those with pre-existing medical conditions. The design of our urban infrastructure 13 including Green Infrastructure (GI) such as trees, parks, and green walls 13 determines where air pollution is produced, and how it disperses. Built environment professionals should consider air quality at all stages of urban design and development

First Steps in Air Quality for Built Environment Practitioners

Air pollution is the biggest environmental risk to health. Globally, nine out of ten people live in a city that does not comply with WHO air quality standards. Within the UK, poor outdoor air quality is linked to 50,000 deaths each year. The most vulnerable are children, the elderly, or those with pre-existing medical conditions. The design of our urban infrastructure 13 including Green Infrastructure (GI) such as trees, parks, and green walls 13 determines where air pollution is produced, and how it disperses. Built environment professionals should consider air quality at all stages of urban design and development

Advancements towards restoration of the endangered limpet Patella ferruginea Gmelin, 1791 through controlled reproduction

The ferruginous limpet is one of the most threatened invertebrate species in the Mediterranean Sea. Its controlled reproduction has been considered one of the potentially most effective strategies for the production of juveniles for population restocking or for recolonization of areas where the species was brought to extinction by human pressure but is now under protection (e.g., MPAs). This approach has been pursued for at least two decades but with partial results: at most, some juveniles have been obtained and have reached adult stage, yet not starting from spawning induction but through sacrifice of female specimens (lethal approach), additionally resulting in low genetic diversity of the juveniles produced. Herein, we describe, for the first time, positive results of the spawning induction in P. ferruginea. The fertilizations made after these experiences allow describing the larval development of the species from its early stages to its metamorphosis. The fertilization rate in these spawning events was much higher (>97%) than in previous studies that were based on the extraction of oocytes by dissection. The rate of non-anomalous larvae after 15 hours was not negligible but variable, depending perhaps on the quality of the sperm available at each fertilization. The timing of larval development of the species and its variability, particularly regarding metamorphosis, are described. Settlement ability is reached at 3\u20134 days after fertilization, depending on water temperature, while a large variability is observed in metamorphosis, occurring between 7 and 32 days (probably up to 40 days), although inducing factors are still unknown

Identifying and accounting for the Coriolis Effect in satellite NO2 observations and emission estimates

Recent developments in atmospheric remote sensing from satellites have made it possible to resolve daily emission plumes from industrial point sources, around the globe. Wind rotation aggregation coupled with statistical fitting is commonly used to extract emission estimates from these observations. These methods are used here to investigate how the Coriolis Effect influences the trajectory of observed emission plumes, and to assess the impact of this influence on satellite derived emission estimates. Of the 17 industrial sites investigated, nine showed the expected curvature for the hemisphere they reside in. Five showed no or negligible curvature, and two showed opposing or unusual curvature. The sites which showed conflicting curvature all reside in topographically diverse regions, where strong meso-gamma scale (2&ndash;20 km) turbulence dominates over larger synoptic circulation patterns. For high curvature cases the assumption that the wind-rotated plume aggregate is symmetrically distributed across the downwind axis breaks down, which impairs the quality of statistical fitting procedures. Using NOx emissions from Matimba power station as a test case, not compensating for Coriolis curvature resulted in an10 underestimation of &sim; 9 % on average for years 2018 to 2021. This study is the first formal observation of the Coriolis Effect and its influence on satellite observed emission plumes, and highlight both the variability of emission calculation methods and the need for a standardised scheme for this data to act as evidence for regulators.</p