Accommodating Complex Substitution Patterns in a Random Utility Model of Recreational Fishing

We employed a cross-nested logit (CNL) model that permits a rich pattern of substitution among alternatives within a closed form choice model. The specification we employed is ideal for applications with many choice alternatives, such as the 431 fishing sites in this application. The CNL model provided a significant improvement over multinomial and nested logit model specifications at explaining observed recreational fishing site choices by residents of northern Ontario, Canada. Results from two scenarios illustrated the implications of using the CNL model on spatial substitution patterns and welfare measures associated with attribute change scenarios. The CNL model forecasts demonstrated that the relative change in fishing site use was lower at the most affected sites and higher at sites near the affected sites than was predicted by the multinomial logit model. No consistent pattern was found in mean or variance of welfare estimates associated with hypothetical attribute changes.Compensating variation, cross-nested logit, fishing site choice, random utility model, spatial substitution, Demand and Price Analysis, Institutional and Behavioral Economics, Q26,

An inter-comparison of Arctic synoptic scale storms between four global reanalysis datasets

The Arctic is becoming more accessible as sea ice extent continues to decline, resulting in higher human exposure to Arctic storms. This study compares Arctic storm characteristics between the ECMWF-Interim Reanalysis, 55-year Japanese Reanalysis, NASA-Modern Era Retrospective Analysis for Research and Applications Version 2 and National Centre for Environmental Prediction-Climate Forecast System Reanalysis datasets between 1980 and 2017, in winter (DJF) and summer (JJA). It is shown that Arctic storm characteristics are sensitive to the variable used for storm tracking. Arctic storm frequency is found to be similar in summer and winter when using sea level pressure minima to track Arctic storms, whereas, the storm frequency is found to be higher in winter than summer when using 850 hPa relative vorticity to track storms, based on using the same storm tracking algorithm. It is also found that there are no significant trends in Arctic storm characteristics between 1980 and 2017. Given the sparsity of observations in the Arctic, it might be expected that there are large differences in Arctic storm characteristics between the reanalysis datasets. Though, some similar Arctic storm characteristics are found between the reanalysis datasets, it is found that the differences in Arctic storm characteristics between the reanalysis datasets are generally higher in winter than in summer. Overall, the results show that there are differences in Arctic storm characteristics between reanalysis datasets, but even larger differences can arise between using 850 hPa relative vorticity or mean sea level pressure as the storm tracking variable, which adds to the uncertainty associated with current Arctic storm characteristics

Atmospheric response in summer linked to recent Arctic sea ice loss

Since 2007 a large decline in Arctic sea ice has been observed. The large-scale atmospheric circulation response to this decline is investigated in ERA-Interim reanalyses and HadGEM3 climate model experiments. In winter, post-2007 observed circulation anomalies over the Arctic, North Atlantic and Eurasia are small compared to interannual variability. In summer, the post-2007 observed circulation is dominated by an anticyclonic anomaly over Greenland which has a large signal-to-noise ratio. Climate model experiments driven by observed SST and sea ice anomalies are able to capture the summertime pattern of observed circulation anomalies, although the magnitude is a third of that observed. The experiments suggest high SSTs and reduced sea ice in the Labrador Sea lead to positive temperature anomalies in the lower troposphere which weaken the westerlies over North America through thermal wind balance. The experiments also capture cyclonic anomalies over Northwest Europe, which are consistent with downstream Rossby wave propagatio

Representation of western disturbances in CMIP5 models

Western disturbances (WDs) are synoptic extratropical disturbances embedded in the subtropical westerly jet stream. They are an integral part of the South Asian winter climate, both for the agriculture-supporting precipitation they bring to the region and for the associated isolated extreme events that can induce devastating flash flooding. Here, WD behaviour and impacts are characterised in 23 CMIP5 historical simulations and compared with reanalysis and observations. It is found that WD frequency has a strong relationship with model resolution: higher resolution models produce significantly more WDs, and a disproportionately high fraction of extreme events. Exploring metrics of jet strength and shape, we find that the most probable cause of this relationship is that the jet is wider in models with coarser resolution, and therefore the northern edge in which WDs are spun up sits too far north of India. The frequency of WDs in both winter and summer is found to be overestimated by most models, and thus the winter frequency of WDs estimated from the multi-model mean (30 winter−1) is above the reanalysis mean (26 winter−1). In this case, the error cannot be adequately explained by local jet position and strength. Instead, we show that it is linked with a positive bias in upstream mid-tropospheric baroclinicity. Despite a positive winter precipitation bias in CMIP5 models over most of India and Pakistan and a dry bias in the western Himalaya, the fraction of winter precipitation for which WDs are responsible is accurately represented. Using partial correlation, it is shown that the overestimation in WD frequency is the largest contributor to this bias, with a secondary, spatially heterogeneous contribution coming from the overestimation of WD intensity

Evaluation of the onset of space charge and electroluminescence as a marker for cross linked polyethylene ageing

The aim of the “ARTEMIS” project is to investigate the ageing mechanisms for cross-linked polyethylene under thermo-electrical stress and to identify ageing markers, which can be used to carry out diagnostic procedures. A carefully selected set of techniques which can give cross-correlated information on space charge phenomenology and material degradation were used to investigate specimens peeled from reference and aged cables. The paper shows that ageing induces a change in the density and depth of trapping levels, and an increase in the number and size of mesovoids. Interpretation of these results is discussed in terms of physico-chemical modifications, which can affect trap distribution and microstructure

Falling trend of western disturbances in future climate simulations

Western disturbances (WDs) are synoptic-scale cyclonic weather systems advected over Pakistan and north India by the subtropical westerly jet stream. There, they are responsible for most of the winter precipitation, crucial for agriculture of the rabi crop, as well as more extreme precipitation events, which can lead to local flooding and avalanches. Despite their importance, there has not yet been an attempt to objectively determine the fate of WDs in future climate GCMs. Here, a tracking algorithm is used to build up a catalogue of WDs in both CMIP5 historical and representative concentration pathway (RCP) experiments of the future. It is shown that in business-as-usual (RCP8.5) future climate simulations, WD frequency falls by around 15% by the end of the twenty-first century, with the largest relative changes coming in pre- and post-monsoon months. Meanwhile, mean WD intensity will decrease, with central vorticity expected to become less cyclonic by about 12% over the same period. Changes in WD frequency are attributed to the projected widening and weakening of the winter subtropical jet; as well as decreasing meridional wind shear and mid-tropospheric baroclinic vorticity tendency, which also explain the changes in intensity. Finally, the impact of these changes on regional precipitation is explored. The decline in WD frequency and intensity will cause a decrease in mean winter rainfall over Pakistan and north India amounting to about 15% of the mean -- subject to the ability of the models to represent the processes responsible. The effect on extreme precipitation events, however, remains unclear

Wrack Lines Volume 22, Number 2, Fall-Winter 2022-2023

With the theme, Looking Ahead: People and Projects Shaping the Future, the Fall-Winter 2022-2023 leads with the first in what will be a series of articles about offshore wind development impacting Connecticut. That is followed by the inspiring story of how a dying forest was replanted for climate resilience. Next, a profile of longtime marine educator Tim Visel tells about his lasting impact on Connecticut schools and students. Lastly, the complex challenge of dealing with Contaminants of Emerging Concern is examined, with descriptions of how Sea Grant is involved and the particularly troublesome group of substances called PFAS

Microwave irradiation enhances the <i>in vitro </i>antifungal activity of citrus by-product aqueous extracts against <i>Alternaria alternata</i>

The effect of two lemon by-product aqueous extracts at different concentrations (14, 7, 3.5 and 1 mg mL−1) was tested against the in vitro growth of Alternaria alternata. Prior to extraction, one batch of by-product was dehydrated by freeze-drying (untreated by-product), while the other batch was treated by microwave irradiation in conjunction with freeze-drying (microwave-treated by-product). High-performance liquid chromatography (HPLC) was employed for the identification of individual phenolic compounds with potent antifungal activities. Both lemon by-product aqueous extracts inhibited the mycelial growth and suppressed the spore germination of the fungus in a concentration-dependent manner. In general, the extracts obtained from the microwave-treated lemon by-product displayed enhanced antifungal activity than those obtained from the untreated one. Scanning electron microscopy (SEM) revealed that both lemon by-product extracts affected the hyphal morphology of the fungus. The antifungal activity of the extracts was attributed to their phenolic acid and ascorbic acid contents

Modelado y control de un captador solar tipo Fresnel

XXXII Jornadas Nacionales de Automática Sevilla 2011En este artículo se presenta el modelado matemático, así como algoritmos de control de un captador solar tipo Fresnel que pertenece planta de refrigeración solar situada en la Escuela Superior de Ingenieros de la Universidad de Sevilla. Se va a desarrollar un modelo de parámetros distribuidos, ajustando los parámetros del mismo con datos tomados del sistema real y comparando la respuesta del modelo con la salida del sistema. Por último, se implementará una estrategia de control clásica, un PID con un compensador de perturbaciones de tipo feedforward paralelo, cuyo desempeño será validado mediante simulación usando el modelo de parámetros distribuidos.Unión Europea DPI 2008-05818Junta de Andalucía P07-TEP-0272

Large-scale and synoptic meteorology in the south-east Pacific during the observations campaign VOCALS-REx in austral Spring 2008

We present a descriptive overview of the meteorology in the south eastern subtropical Pacific (SEP) during the VOCALS-REx intensive observations campaign which was carried out between October and November 2008. Mainly based on data from operational analyses, forecasts, reanalysis, and satellite observations, we focus on spatio-temporal scales from synoptic to planetary. A climatological context is given within which the specific conditions observed during the campaign are placed, with particular reference to the relationships between the large-scale and the regional circulations. The mean circulations associated with the diurnal breeze systems are also discussed. We then provide a summary of the day-to-day synoptic-scale circulation, air-parcel trajectories, and cloud cover in the SEP during VOCALS-REx. Three meteorologically distinct periods of time are identified and the large-scale causes for their different character are discussed. The first period was characterised by significant variability associated with synoptic-scale systems interesting the SEP; while the two subsequent phases were affected by planetary-scale disturbances with a slower evolution. The changes between initial and later periods can be partly explained from the regular march of the annual cycle, but contributions from subseasonal variability and its teleconnections were important. Across the whole of the two months under consideration we find a significant correlation between the depth of the inversion-capped marine boundary layer (MBL) and the amount of low cloud in the area of study. We discuss this correlation and argue that at least as a crude approximation a typical scaling may be applied relating MBL and cloud properties with the large-scale parameters of SSTs and tropospheric temperatures. These results are consistent with previously found empirical relationships involving lower-tropospheric stability