This is the first of two papers that describe the generation of a 25-member perturbed parameter ensemble (PPE) of high-resolution, global coupled simulations for the period 1900–2100, using CMIP5 historical and RCP8.5 emissions. Fifteen of these 25 coupled simulations now form a subset of the global projections provided for the UK Climate Projections 2018 (UKCP18). This first paper describes the selection of 25 variants (combinations of 47 parameters) using a set of cheap, coarser-resolution atmosphere-only simulations from a large sample of nearly 3000 variants. Retrospective 5-day weather forecasts run at climate resolution, and simulations of 2004–2009 with prescribed SST and sea ice are evaluated to filter out poor performance. We opted for a single design choice and sensitivity tests were done after the PPE was generated to demonstrate the effect of design choices on the filtering. Given our choice, only 38 of the parameter combinations were found to have acceptable performance at this stage. Idealised atmosphere-only simulations were then used to select the subset of 25 members that were as diverse as possible in terms of their CO2 and aerosol forcing, and their response to warmer SSTs. Using our parallel set of atmosphere-only and coupled PPEs (the latter from paper 2), we show that local biases in the atmosphere-only experiments are generally informative about the biases in the coupled PPE. Biases in radiative fluxes and cloud amounts are strongly informative for most regions, whereas this is only true for a smaller fraction of the globe for precipitation and dynamical variables. Therefore, the cheap experiments are an affordable way to search for promising parameter combinations but have limitations.
Spatial multi-criteria evaluation (MCE) techniques aid urban planning management by analyzing decision problem alternatives for solutions to help inform decision-making. However, there is a lack of such methods that incorporate the temporal dimension, an important factor when analyzing the dynamic urban landscape and decisions surrounding its changes. A novel spatio-temporal MCE approach is proposed that operates in three-dimensional (3D) space and time to identify changing suitability values of decision alternatives. This space–time method is implemented to evaluate the suitability of residential units over a 15-year period in part of downtown City of Vancouver, Canada. The results indicate that the majority of units exhibit a decrease in suitability with time due to depreciation and reduction of assets like view and privacy from the construction of new buildings. The proposed method can be used by urban planners and developers to assist in long-term assessments of proposed development scenarios and their impact on existing urban infrastructure. 相似文献
Slushflows are natural hazards that pose considerable danger to communities across the globe. These events are characterized by the rapid mass movement of water-inundated snow downslope, and they cause economic damage as well as fatalities in many different climates and regions. As the global climate changes and human populations and industries potentially expand to higher latitudes, it will be important to fully understand the slushflow hazard since an anticipated increase in the frequency of rain-on-snow events and an earlier spring thaw would likely increase the probability of slushflows. This article: (1) summarizes the factors that favor the development of slushflows; (2) discusses the hazard management implications of slushflows; (3) examines the policies employed to prevent and mitigate slushflow damage; and (4) sets out the need for modifications in hazard management systems. Conclusions drawn hope to address future research needs in an effort to create policies that better suit the needs of at-risk communities. 相似文献
Natural Hazards - Formal engineering hurricane evacuation studies have not typically considered inland flooding explicitly, though it has been shown repeatedly to be a major cause of damage and... 相似文献
The resolution of conflicting fluvial (allochthonic erosion and deposition) and bioturbation (autochthonic faunal turbation) theories of stone line formation has important implications for tropical geomorphology—with the former indicating dynamic, punctuated landscape development and the latter implying relative landscape stability with ongoing moderate erosion. On a gentle hill in central Uganda, we quantitatively characterized and statistically modeled gravel distributions for 93 profiles. Elemental analysis of K, selected rare-earth elements (REE) and appropriate index elements were employed to test for compositional differences between soils above and saprolite below hilltop stone lines. We also excavated and carefully described four indicative profiles. The results of this study were difficult to reconcile with the bioturbation theory of stone line formation. Important findings included (i) the lack of a consistent gravel-free biomantle with a weak connection between biomantle thickness and stone-line depth, (ii) highly variable stone line depth with a strong inverse relationship between stone line depth and maximum gravel content, (iii) unweathered and rounded cobbles in a stone line over saprolite with angular, highly weathered quartz, and (iv) a statistically significant geochemical difference between soils and saprolites, with evidence of a less weathered surface mantle over more weathered saprolite. These findings indicated a sedimentary origin for soils at this site—even for what is presently a flat, geomorphically isolated hilltop. Evidence from this study and previous work on the geochemistry of this site [Geochim. Cosmochim. Acta 67 (2003) 2711] suggests that the contemporary hilltop once occupied a lower landscape position. 相似文献