Regional and seasonal intercomparison of CMIP3 and CMIP5 climate model ensembles for temperature and precipitation   总被引：2，自引：1，他引：1  

Devashish Kumar  Evan Kodra  Auroop R. Ganguly 《Climate Dynamics》2014,43(9-10):2491-2518

Regional and seasonal temperature and precipitation over land are compared across two generations of global climate model ensembles, specifically, CMIP5 and CMIP3, through historical twentieth century skills and multi-model agreement, and twenty first century projections. A suite of diagnostic and performance metrics, ranging from spatial bias or model-consensus maps and aggregate time series plots, to measures of equivalence between probability density functions and Taylor diagrams, are used for the intercomparisons. Pairwise and multi-model ensemble comparisons were performed for 11 models, which were selected based on data availability and resolutions. Results suggest little change in the central tendency or variability or uncertainty of historical skills or consensus across the two generations of models. However, there are regions and seasons, at different levels of aggregation, where significant changes, performance improvements, and even degradation in skills, are suggested. The insights may provide directions for further improvements in next generations of climate models, and in the meantime, help inform adaptation and policy.  相似文献   

Regional and global projections of twenty-first century glacier mass changes in response to climate scenarios from global climate models   总被引：1，自引：0，他引：1  

Valentina Radić  Andrew Bliss  A. Cody Beedlow  Regine Hock  Evan Miles  J. Graham Cogley 《Climate Dynamics》2014,42(1-2):37-58

A large component of present-day sea-level rise is due to the melt of glaciers other than the ice sheets. Recent projections of their contribution to global sea-level rise for the twenty-first century range between 70 and 180 mm, but bear significant uncertainty due to poor glacier inventory and lack of hypsometric data. Here, we aim to update the projections and improve quantification of their uncertainties by using a recently released global inventory containing outlines of almost every glacier in the world. We model volume change for each glacier in response to transient spatially-differentiated temperature and precipitation projections from 14 global climate models with two emission scenarios (RCP4.5 and RCP8.5) prepared for the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. The multi-model mean suggests sea-level rise of 155 ± 41 mm (RCP4.5) and 216 ± 44 mm (RCP8.5) over the period 2006–2100, reducing the current global glacier volume by 29 or 41 %. The largest contributors to projected global volume loss are the glaciers in the Canadian and Russian Arctic, Alaska, and glaciers peripheral to the Antarctic and Greenland ice sheets. Although small contributors to global volume loss, glaciers in Central Europe, low-latitude South America, Caucasus, North Asia, and Western Canada and US are projected to lose more than 80 % of their volume by 2100. However, large uncertainties in the projections remain due to the choice of global climate model and emission scenario. With a series of sensitivity tests we quantify additional uncertainties due to the calibration of our model with sparsely observed glacier mass changes. This gives an upper bound for the uncertainty range of ±84 mm sea-level rise by 2100 for each projection.  相似文献   

Kernel distributed residual function in a revised multiple order autoregressive model and its applications in hydrology     

Nesa Ilich  Amr Gharib  Evan G. R. Davies 《水文科学杂志》2013,58(12):1745-1758

ABSTRACT

This paper describes a new approach to fill missing data in hydrologic series. Based on a multiple-order autoregressive model, our algorithm represents the random term with an empirical distribution function that includes different parameters for the low, medium and high ranges of the modelled hydrologic variable. The algorithm involves a corrective mechanism that preserves the original statistical distribution of the series that are filled, while also eliminating the possibility of obtaining negative values for low flows. The algorithm requires multiple correlated hydrologic time series with sufficient data to permit accurate calculation of their statistical properties. It ensures that both the original statistical dependence among the data series and the statistical distribution functions will be preserved after the missing data had been filled. The model has been tested using 15 streamflow series in the Upper Bow River watershed in Alberta, Canada.  相似文献   

Legacy sediment stored in sinkholes: a case study of three urban watersheds in Tennessee,United States of America     

Evan A. Hart 《自然地理学》2014,35(6):514-531

As closed topographic depressions, sinkholes effectively divide karst regions into a series of subwatersheds, where swallets within each sinkhole define the downstream end of each subwatershed. Water and sediment are temporarily stored in sinkholes before continuing to underground streams. While pathways and travel times of water in karst terrain are commonly found using tracing techniques, such techniques do not provide information about the movement and travel time of sediment through these systems. This paper reviews the literature regarding sediment storage within sinkholes and presents a case study, the objective of which is to estimate the magnitude and timing of sediment deposition within three sinkholes in an urbanized area in Tennessee, United States of America. Sedimentation rates in sinkholes were estimated based on age determination of cultural artifacts (buried trash and coal fragments) and by ¹⁴C dating. For the three study sinkholes, minimum deposition rates (maximum residence times) were 15?cm?yr ^?1(6 yrs), 1.5?cm?yr ^?1(81?yrs), and 0.2?cm?yr^?1(640 yrs). The analysis revealed that sinkholes undergo fill and flush cycles at different timescales caused by changes in upland sediment supply and morphologic changes at swallet openings. Sinkholes that lack swallet openings, or with swallets that have become blocked by debris, are effectively disconnected from master streams with regard to sediment. Sediment stored in sinkholes may be released downstream when swallet conditions change.  相似文献   

Where Is the Money?     

Evan K. Nyer 《Ground Water Monitoring & Remediation》1994,14(2):100-104

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Emerging trends in state regulation of private communities in the U.S.   总被引：1，自引：0，他引：1  

Evan McKenzie 《GeoJournal》2006,66(1-2):89-102

Common interest housing (CIDs), which includes nearly all gated communities as well as non-gated but privately governed neighbourhoods, has become the predominant form of new housing construction in America. Optimistic early assessments that CIDs would prove to be more efficient alternative to municipalities are confronted by the fact of high levels of conflict and litigation, which are proving costly to residents as well as local governments. These conflicts are often highly publicized in the press, leading to concerns in the real estate industry that the demand for such housing could be jeopardized. The conflicts arise from having unpaid, untrained volunteer directors carrying out what were once municipal government functions, and concern financial issues as well as alleged abuses of power by association boards. In response to some of these concerns, across the nation, small but vocal ant-HOA owners groups are organizing, using the internet as their medium and gaining attention from the press. A consensus is emerging that the law governing private communities needs major changes, and different approaches are proposed or being implemented in several states. This paper examines these emerging regulatory trends and offers an assessment of their prospects.  相似文献   

WEB-IS (integrated system): an overall view     

Yunsong Wang  Evan F. Bollig  Benjamin J. Kadlec  Zachary A. Garbow  Gordon Erlebacher  David A. Yuen  Maxwell Rudolph  Lilli X. Yang  Erik O. D. Sevre 《Visual Geosciences》2005,10(1):27-42

WEB-IS, Web-based Integrated System, allows remote, interactive visualization of large-scale 3-D data over the Internet, along with data analysis and data mining. In this paper, we discuss the overall structure of WEB-IS. Up until now we have developed three sub-modules geared towards geophysical problems. WEB-IS1 allows geoscientists to navigate through their 3-D geophysical data, such as seismic structures or numerical simulations, and interactively analyze the statistics or apply data-mining techniques, such as cluster analysis. WEB-IS2 lets a user control Amira (a powerful 3-D visualization package) remotely and analyze, render and view large datasets across the Internet. WEB-IS3 is an imaging service that enables the user to control the scale of features to view through interactive zooming. In the near future, we propose to integrate the three components together through a middleware framework called NaradaBrokering (iNtegrated Asynchronous Real-time Adaptive Distributed Architecture, a distributed messaging infrastructure that can be used to intelligently route data between the originators and registered consumers) without regard for time or location. As a result, WEB-IS will improve its scalability and acquire properties of fault-tolerance. WEB-IS uses a combination of Java, C++, and through the use of NaradaBrokering will seamlessly integrate the server-side processing and user interaction utilities on the client. The server takes care of the processor intensive tasks, such as visualization and data mining, and sends either the resulting bitmap image or statistical results to the middleware across the Internet for viewing. WEB-IS is an easy-to-use service, which will eventually help geoscientists collaborate from different sites in a natural manner. It will be very useful in the next 10 years because of the increasing number of space missions and geophysical campaigns.  相似文献   

Treatment Technology/A Lost Generation     

Evan K. Nyer  Pedro Fierro  Brian Guillette 《Ground Water Monitoring & Remediation》2002,22(4):34-38

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Site Closure Through Alchemy     

Evan K. Nyer 《Ground Water Monitoring & Remediation》2003,23(3):30-32

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Developing a Healthy Disrespect for Numbers     

Evan K. Nyer  Terry Regan  Deepak Nautiyal 《Ground Water Monitoring & Remediation》1996,16(2):59-64

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