124 research outputs found
The match between climate services demands and Earth System Models supplies
Earth System Models (ESM) are key ingredients of many of the climate services that are currently being developed and delivered. However, ESMs have more applications than the provision of climate services, and similarly many climate services use more sources of information than ESMs. This discussion paper elaborates on dilemmas that are evident at the interface between ESMs and climate services, in particular: (a) purposes of the models versus service development, (b) gap between the spatial and temporal scales of the models versus the scales needed in applications, and (c) Tailoring climate model results to real-world applications. A continued and broad-minded dialogue between the ESM developers and climate services providers’ communities is needed to improve both the optimal use and direction of ESM development and climate service development. We put forward considerations to improve this dialogue between the communities developing ESMs and climate services, in order to increase the mutual benefit that enhanced understanding of prospects and limitations of ESMs and climate services will bring.This work and its contributors (B. van den Hurk, C. Hewitt, J. Bessembinder, F. Doblas-Reyes, R. Döscher) were funded by the
Horizon 2020 Framework Programme of the European Union: Project ref. 689029 (Climateurope project). The co-author and editor of the journal states that she was not involved in the review process of the
paper.Peer ReviewedPostprint (published version
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Tropical and mid-latitude teleconnections interacting with the Indian summer monsoon rainfall: a theory-guided causal effect network approach
The alternation of active and break phases in Indian summer monsoon (ISM) rainfall at intraseasonal timescales characterizes each ISM season. Both tropical and mid-latitude drivers influence this intraseasonal ISM variability. The circumglobal teleconnection observed in boreal summer drives intraseasonal variability across the mid-latitudes, and a two-way interaction between the ISM and the circumglobal teleconnection pattern has been hypothesized. We use causal discovery algorithms to test the ISM circumglobal teleconnection hypothesis in a causal framework. A robust causal link from the circumglobal teleconnection pattern and the North Atlantic region to ISM rainfall is identified, and we estimate the normalized causal effect (CE) of this link to be about 0.2 (a 1 standard deviation shift in the circumglobal teleconnection causes a 0.2 standard deviation shift in the ISM rainfall 1 week later). The ISM rainfall feeds back on the circumglobal teleconnection pattern, however weakly. Moreover, we identify a negative feedback between strong updraft located over India and the Bay of Bengal and the ISM rainfall acting at a biweekly timescale, with enhanced ISM rainfall following strong updraft by 1 week. This mechanism is possibly related to the boreal summer intraseasonal oscillation. The updraft has the strongest CE of 0.5, while the Madden–Julian oscillation variability has a CE of 0.2–0.3. Our results show that most of the ISM variability on weekly timescales comes from these tropical drivers, though the mid-latitude teleconnection also exerts a substantial influence. Identifying these local and remote drivers paves the way for improved subseasonal forecasts
Effect of environmental humidity on the creep behavior of flax fiber-reinforced polymer composites
Flax fiber-reinforced polymer (FFRP) composites are emerging popular environmental-friendly construction materials. However, their significant creep properties have been a major concern for using FFRP in load-bearing structures. This article presents an investigation of the effect of environmental humidity on the creep behavior of the FFRP. Samples with flax fiber in 0°, 90°, and ± 45° were manufactured, respectively, by the vacuum infusion method. Accelerated creep tests were conducted on samples in different relative humidities (RH), and the results were analyzed by the time–temperature superposition principle (TTSP). It is found the creep development of samples with 0° and 90° fiber increases with the RH, and their 30-year total strain in 97% RH is about 10 times higher than that in 11% RH. The samples with ±45° fiber are found not obviously sensitive to the humidity change. The scanning electron microscope (SEM) check indicates the change in the fiber–matrix interface and cracks between microfibrils in a fiber bundle is the main reason for the change of creep behavior in high humidity. This study may benefit the design of structures made of natural fiber-reinforced polymer composites, especially for load-bearing structures working in high-humidity environments.</p
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Should seasonal rainfall forecasts be used for flood preparedness?
In light of strong encouragement for disaster managers to use climate services for flood preparation, we question whether seasonal rainfall forecasts should indeed be used as indicators of the likelihood of flooding. Here, we investigate the primary drivers of flooding at the seasonal timescale across sub-Saharan Africa. Given the sparsity of hydrological observations, we input bias-corrected reanalysis rainfall into the Global Flood Awareness System to identify seasonal indicators of floodiness. Results demonstrate that in wet climates, even a perfect tercile forecast of seasonal total rainfall would provide little to no indication of the seasonal likelihood of flooding. The number of extreme events within a season shows the highest correlations with floodiness consistently across regions. Otherwise, results vary across climate regimes: floodiness in arid regions in Southern and Eastern Africa shows the strongest correlations with seasonal average soil moisture and seasonal total rainfall. Floodiness in wetter climates of West and Central Africa and Madagascar shows the strongest relationship with measures of the intensity of seasonal rainfall. Measures of rainfall patterns, such as the length of dry spells, are least related to seasonal floodiness across the continent. Ultimately, identifying the drivers of seasonal flooding can be used to improve forecast information for flood preparedness, and avoid misleading decision-makers
Living with sea-level rise in North-West Europe: Science-policy challenges across scales
Sea-level rise (SLR) confronts coastal societies and stakeholders with increasing hazards and coastal risks with large uncertainties associated to these changes. Adaptation to SLR requires societal and policy decision-making to consider these changing risks, which are in turn defined by socio-economic development objectives and the local societal context. Here, we review some of the key challenges facing governments, stakeholders and scientists in adapting to SLR, and key aspects of successful adaptation, by exploring different approaches to SLR and coastal adaptation planning in three western European countries, the Netherlands, Germany and the United Kingdom. Several common challenges of SLR adaptation emerge across the different settings, including the inherent uncertainty regarding future conditions, the significant social and socio-economic consequences, the consideration and distribution of (residual) risk over communities, and the long legacy of present-day decisions that affect future risk and management options supporting future generations. These challenges are addressed differently in the three countries, e.g. in the governance level at which adaptation is initiated, although common elements also emerge. One common emerging element is adaptive pathways planning, which entails dynamic decision-making that breaks uncertain decisions into manageable elements or steps over time, while keeping options for the future. Another common element is the development of effective local science-policy interfaces, as engagement of local decision-makers and citizens is essential to manage conflicting interests. Lastly, we find that social and communication sciences have great potential to support effective science-policy interfaces, e.g. though identifying societal tipping points. Yet, in decisions on SLR adaptation, insights from these fields are rarely used to date. We conclude that supporting science-policy interactions for adaptation decision-making at relevant (inter)national to local scales through tailored multi-disciplinary scientific assessments is an important way forward for SLR adaptation in Europe
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Event-based storylines to address climate risk
The climate science community is challenged to adopt an actionable risk perspective, which is difficult to align with the traditional focus on model-based probabilistic climate change projections. Event-based storylines can provide a way out of this conundrum by putting emphasis on plausibility rather than probability. This links directly to common practices in disaster risk management using “stress-testing” for emergency preparedness based on events that are conditional on specific and plausible assumptions. Event-based storylines allow for conditional explanations, without full attribution of every causal factor, which is crucial when some aspects of the latter are complex and highly uncertain
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A vision for hydrological prediction
IMproving PRedictions and management of hydrological EXtremes (IMPREX) was a European Union Horizon 2020 project that ran from September 2015 to September 2019. Its aim was to improve society’s ability to anticipate and respond to future extreme hydrological events in Europe across a variety of uses in the water-related sectors (flood forecasting, drought risk assessment, agriculture, navigation, hydropower, and water supply utilities). Through the engagement with stakeholders and continuous feedback between model outputs and water applications, progress was achieved in better understanding the way hydrological predictions can be useful to (and operationally incorporated into) problem solving in the water sector. The work and discussions carried out during the project nurtured further reflections towards a common vision for hydrological prediction. In this article, we summarize the main findings of the IMPREX project within a broader overview of hydrological prediction, providing a vision for improving such predictions. In so doing, we firstly present a synopsis of hydrological and weather forecasting, with a focus on medium-range to seasonal scales of prediction for increased preparedness. Second, the lessons learnt from IMPREX are discussed. The key findings are the gaps highlighted in the global observing system of the hydrological cycle, the degree of accuracy of hydrological models and the techniques of post-processing to correct biases, the origin of seasonal hydrological skill in Europe, and user requirements of hydrometeorological forecasts to ensure their appropriate use in decision-making models and practices. Lastly, a vision for how to improve these forecast systems/products in the future is expounded and these include advancing numerical weather and hydrological models, improved earth monitoring, and more frequent interaction between forecasters and users to tailor the forecasts to applications. We conclude that if these improvements can be implemented in the coming years, earth system and hydrological modelling will become more skilful, thus leading to socioeconomic benefits for the citizens of Europe and beyond
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