517 research outputs found
Supplemental_material – Supplemental material for Exercise training for adults hospitalized with an acute respiratory condition: a systematic scoping review
No full textSupplemental material, Supplemental_material for Exercise training for adults hospitalized with an acute respiratory condition: a systematic scoping review by Hayley Rice, Megan Harrold, Robin Fowler, Carol Watson, Grant Waterer and Kylie Hill in Clinical Rehabilitation</p
Love elegies ...
No full textAttributed to William Hayley. cf. Wrenn catalogue.Engraved title vignette.Mode of access: Internet
The impact of climate change on extreme precipitation in Sicily, Italy
No full textIncreasing precipitation extremes are one of the possible consequences of a warmer climate. These may exceed the capacity of urban drainage systems, and thus impact the urban environment. Because short-duration precipitation events are primarily responsible for flooding in urban systems, it is important to assess the response of extreme precipitation at hourly (or sub-hourly) scales to a warming climate. This study aims to evaluate the projected changes in extreme rainfall events across the region of Sicily (Italy) and, for two urban areas, to assess possible changes in Depth-Duration-Frequency (DDF) curves. We used Regional Climate Model outputs from Coordinated Regional Climate Downscaling Experiment for Europe area ensemble simulations at a ~12 km spatial resolution, for the current period and 2 future horizons under the Representative Concentration Pathways 8.5 scenario. Extreme events at the daily scale were first investigated by comparing the quantiles estimated from rain gauge observations and Regional Climate Model outputs. Second, we implemented a temporal downscaling approach to estimate rainfall for sub-daily durations from the modelled daily precipitation, and, lastly, we analysed future projections at daily and sub-daily scales. A frequency distribution was fitted to annual maxima time series for the sub-daily durations to derive the DDF curves for 2 future time horizons and the 2 urban areas. The overall results showed a raising of the growth curves for the future horizons, indicating an increase in the intensity of extreme precipitation, especially for the shortest durations. The DDF curves highlight a general increase of extreme quantiles for the 2 urban areas, thus underlining the risk of failure of the existing urban drainage systems under more severe events
Sensitivity of extreme rainfall to temperature in semi-arid Mediterranean regions
No full textWarmer air has the potential to hold more water vapour and, therefore, to provide more water to rainfall events. Studying the relationship between rainfall and temperature represents an emerging issue in hydrology and meteorology, since it can be considered fundamental for evaluating the effects of global warming on future precipitation. Various approaches have been tested across different parts of the world, in many cases observing an intensification of extreme precipitation at higher temperatures consistent with the well-known thermodynamic Clausius-Clapeyron relation (CC-scaling rate of 6–7%°C −1 ). However, at different locations for hourly time-scales, the temperature-extreme rainfall scaling can be higher (super-CC) or lower (sub-CC). This study contributes to the understanding of the scaling relationship between extreme rainfall and temperature under climate conditions characteristic of Mediterranean semi-arid regions, rarely explored in the past. The role of different factors, such as rainfall characteristics and climatic seasonality, modelling framework and rainfall accumulation period are investigated through an application to Sicily (Italy). In particular, the suitability of different types of regression models used to interpret the relationship between hourly and sub-hourly extreme rainfall and surface temperature is explored. We find overall a sub-CC scaling for most of the island of Sicily. However, the rainfall-temperature scaling relationship is not constant over the temperature range and may be dependent on the season. The different results obtained highlight the importance of modelling choices for analyses in regions characterized by semi-arid climates. More specifically, we observe increasing scaling rates for decreasing rainfall accumulation periods, and significant sensitivity of scaling rates to the selected extreme rainfall quantile. Our novel use of piecewise and locally-weighted scatter plot smoothing regression-based approaches allow the accurate characterization of the temperature dependence of extreme rainfall in Sicily. This identifies a peak-like structure for the drier season, not detected by the simple application of the commonly-used exponential regression based approach
A simple and robust approach for adapting design storms to assess climate-induced changes in flash flood hazard
No full textISSN:0309-1708ISSN:1872-9657ISSN:1872-965
The relationship between precipitation depth and weather circulation patterns over Sicily
No full textSome weather circulation patterns (WPs) derived by the UK Met Office and defining a certain type of atmospheric circulation over Europe have been recently used to analyze the relationship of the regional UK precipitation and drought with respect to the atmospheric circulation over Europe (Richardson et al. 2018). In this study, we attempt to find out one or more relationships between precipitation depth and weather patterns over a non UK-centred domain, such as Sicily (Italy), which is characterized by a totally different climate as compared to the climate of UK. Since the island has been affected by many floods in the last years, occurred as a consequence of extreme rainfall events, it would be very important to understand if there exist some European WPs that are responsible for causing extreme rainfall events on the island. This aspect could be very helpful in reducing the flood risk, since it would make it possible to prevent extreme rainfall events, almost likely leading to floods, by simply preventing the atmospheric circulation with a meteorological model
Influence of temporal data aggregation on trend estimation for intense rainfall
No full textDue to their influence on design guidelines, there is great interest in quantifying the possible impacts of climate change on extreme rainfall return levels. These studies can be affected by existing distortions in available rainfall historical series. The effect of the temporal aggregation (or time resolution), ta, of rainfall observations on the estimation of trends in annual maxima over the last 100 years is examined here. We have used long-term historical rainfall observations with various temporal aggregations, due to the progress of recording systems through time, at 10 representative meteorological stations located in an inland region of Central Italy. Series of annual maximum rainfall depths, Hd, for given durations, d, have been then derived. It is well known that Hd values derived from rainfall data characterized by every ta may involve underestimation errors, that for ta> ≈10 min can become important. Considering that all selected stations were installed in the first half of the twentieth century, each Hd series can be assumed as inhomogeneous since it contains values obtained by rainfall data with ta values ranging from fine (e.g. 1 min) to coarse (e.g. 24 h),thus with different levels of underestimation. By using a recently developed mathematical relation between average underestimation error and the ratio ta/d, we then correct each Hd value has been corrected through two different approaches, obtaining quasi-homogeneous series. Successively, commonly used climatic trend tests, including least-squares linear trend analysis, Mann-Kendall, Spearman's rank correlation, and Sen's method, have been applied to the inhomogeneous and quasi-homogeneous Hd series. The results show that the underestimation of Hd values with coarse ta plays a significant role in the analysis of the effects of climatic change on extreme rainfalls. Specifically, the correction of the Hd values can change the sign of the trend from positive to negative, mainly for series characterized by high probability to include Hd values with ta/d = 1
Relation between storm characteristics and extreme precipitation statistics over CONUS
No full textIn this paper we use a statistical framework to analyze the relation between storm properties and the statistics of extreme precipitation. We identify storm events using a 24-hour dry hiatus separation. We investigate the statistics of the hourly maximum intensity for the heaviest storm events at durations of 1 and 24 h. A two-parameter Weibull distribution is used to represent precipitation frequencies at several stations from a quality-controlled hourly precipitation dataset over the contiguous United States, encompassing seven climate zones. The Spearman correlation between the distribution parameters and a selection of storm properties (duration, intensity, decorrelation time, convective-like ratio) and station properties (elevation and latitude) is used to measure the relation of these properties with the statistics of extreme precipitation. Our results indicate that observed annual maximum hourly precipitation over the entire study area are likely samples from the used distribution, implying that a two-parameter Weibull distribution is suitable for modeling hourly and 24-hour precipitation extremes over the contiguous United States. The spatial variability of shape parameters obtained for hourly events showed lighter tails in the west coast when compared to the rest of CONUS, while the centralnorth displays heavier tails. We identify statistically significant links (at the 95% confidence level) between storm characteristics connected with the underlying processes (e.g., typical storm duration, typical temporal autocorrelation, proportion of convective-like storms) and the parameters of the distribution. Notably, characteristics typical of convective precipitation, e.g., sharp decorrelation time and high hourly intensity, tend to be related to distributions with heavier tails. These results provide a first step towards linking the characteristics of storms with the local statistics of extremes
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