Application of an extreme winter storm scenario to identify vulnerabilities,mitigation options,and science needs in the Sierra Nevada mountains,USA     

Christine M. Albano  Michael D. Dettinger  Maureen I. McCarthy  Kevin D. Schaller  Toby L. Welborn  Dale A. Cox 《Natural Hazards》2016,80(2):879-900

  相似文献   

Aspects of wave behaviour in the mid‐ and upper troposphere of the southern Hemisphere     

Kevin Hamilton 《大气与海洋》2013,51(1):40-54

Abstract

The zonal wavenumber spectra of the geopotential heights of the 300‐ and 500‐mb surfaces in the Southern Hemisphere were determined for each month between May 1972 and November 1979 using daily operational analyses produced by the Australian Bureau of Meteorology. During over one‐quarter of the “summer” months (November through March) there are very prominent peaks at zonal wavenumber five in the region of the mid‐latitude jet (～35–60°S). Frequently wavenumber five totally dominates the eddy fields in individual daily maps so that height contours in mid‐latitudes take on virtually pentagonal shapes. During periods when wavenumber 5 is prominent, it is observed to propagate eastward in a very regular manner with a period of about eleven days. All these findings are consistent with Salby's (1982) earlier results concerning the Southern Hemisphere height fields during the first few months of the FGGE experiment.

There is little evidence for a similar phenomenon in the winter circulation of the Southern Hemisphere.  相似文献   

A CO2-rich gas trigger of explosive paroxysms at Stromboli basaltic volcano,Italy     

Patrick Allard 《Journal of Volcanology and Geothermal Research》2010,189(3-4):363-374

In addition to rhythmic slug-driven Strombolian activity, Stromboli volcano occasionally produces discrete explosive paroxysms (2 per year on average for the most frequent ones) that constitute a major hazard and whose origin remains poorly elucidated. Partial extrusion of the volatile-rich feeding basalt as aphyric pumice during these events has led to consider their triggering by the fast ascent of primitive magma blobs from possibly great depth. Here I examine and discuss the alternative hypothesis that most of the paroxysms could be triggered and driven by the fast upraise of CO₂-rich gas pockets generated by bubble foam growth and collapse in the sub-volcano plumbing system. Data for the SO₂ and CO₂ crater plume emissions are used to show that Stromboli's feeding magma may originally contain as much as 2 wt.% of carbon dioxide and early coexists with an abundant CO₂-rich gas phase with high CO₂/SO₂ molar ratio (≥ 60 at 10 km depth below the vents, compared to ～ 7 in time-averaged crater emissions). Pressure-related modelling indicates that the time-averaged crater gas composition and output are well accounted for by closed system decompression of the basalt–gas mixture until the volcano–crust interface (～ 3 km depth), followed by open degassing and crystallization in the volcano conduits. However, both the low viscosity and high vesicularity of the basaltic magma permit bubble segregation and bubble foam growth at deep sill-like feeder discontinuities and at shallower physical boundaries (such as the volcano–crust interface) where the gas-rich aphyric basalt interacts with the unerupted crystal-rich and viscous magma drained back from the volcano conduits. Gas pressure build-up and bubble foam collapse at these boundaries will intermittently trigger the sudden upraise of CO₂-rich gas blobs that constitute the main driving force of the paroxysms. Deeper-sourced gas blobs, driving the most powerful explosions, will be the richest in CO₂ and have highest CO₂/SO₂ ratios. This mechanism is shown to account well for the dynamic, seismic and petrologic features of Stromboli's paroxysms and, hence, to provide a potential alternative interpretation for their genesis and their forecasting. Enhanced bubble foam leakage prior to a paroxysm, or foam emptying in several steps, should lead indeed to precursory upstream of CO₂-rich gas and increasing CO₂/SO₂ ratio in crater plume emissions. The recent detection of such signals prior to two explosions in December 2006 and March 2007 strongly supports this expectation and the model proposed in this study.  相似文献   

Dissolved nitrous oxide (N2O) dynamics in agricultural field drains and headwater streams in an intensive arable catchment          下载免费PDF全文

Zanist Q. Hama‐Aziz  Kevin M. Hiscock  Richard J. Cooper 《水文研究》2017,31(6):1371-1381

Indirect nitrous oxide (N₂O) emissions produced by nitrogen (N) leaching into surface water and groundwater bodies are poorly understood in comparison to direct N₂O emissions from soils. In this study, dissolved N₂O concentrations were measured weekly in both lowland headwater streams and subsurface agricultural field drain discharges over a 2‐year period (2013–2015) in an intensive arable catchment, Norfolk, UK. All field drain and stream water samples were found to have dissolved N₂O concentrations higher than the water–air equilibrium concentration, illustrating that all sites were acting as a net source of N₂O emissions to the atmosphere. Soil texture was found to significantly influence field drain N₂O dynamics, with mean concentrations from drains in clay loam soils (5.3 μg N L^?1) being greater than drains in sandy loam soils (4.0 μg N L^?1). Soil texture also impacted upon the relationships between field drain N₂O concentrations and other water quality parameters (pH, flow rate, and nitrate (NO₃) and nitrite (NO₂) concentrations), highlighting possible differences in N₂O production mechanisms in different soil types. Catchment antecedent moisture conditions influenced the storm event mobilisation of N₂O in both field drains and streams, with the greatest concentration increases recorded during precipitation events preceded by prolonged wet conditions. N₂O concentrations also varied seasonally, with the lowest mean concentrations typically occurring during the summer months (JJA). Nitrogen fertiliser application rates and different soil inversion regimes were found to have no effect on dissolved N₂O concentrations, whereas higher N₂O concentrations recorded in field drains under a winter cover crop compared to fallow fields revealed cover crops are an ineffective greenhouse gas emission mitigation strategy. Overall, this study highlights the complex interactions governing the dynamics of dissolved N₂O concentrations in field drains and headwater streams in a lowland intensive agricultural catchment.  相似文献   

Hydrology and geomorphology of the Upper White Nile lakes and their relevance for water resources management in the Nile basin     

Mohammed El Bastawesy  Safwat Gabr  Kevin White 《水文研究》2013,27(2):196-205

Remote sensing data and digital elevation models were utilized to extract the catchment hydrological parameters and to delineate storage areas for the Ugandan Equatorial Lakes region. Available rainfall/discharge data are integrated with these morphometric data to construct a hydrological model that simulates the water balance of the different interconnected basins and enables the impact of potential management options to be examined. The total annual discharges of the basins are generally very low (less than 7% of the total annual rainfall). The basin of the shallow (5 m deep) Lake Kioga makes only a minor hydrological contribution compared with other Equatorial Lakes, because most of the overflow from Lake Victoria basin into Lake Kioga is lost by evaporation and evapotranspiration. The discharge from Lake Kioga could be significantly increased by draining the swamps through dredging and deepening certain channel reaches. Development of hydropower dams on the Equatorial Lakes will have an adverse impact on the annual water discharge downstream, including the occasional reduction of flow required for filling up to designed storage capacities and permanently increasing the surface areas of water that is exposed to evaporation. On the basis of modelling studies, alternative sites are proposed for hydropower development and water storage schemes. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

Impact of royalties from forest resources on community development in Boki Local Government in Cross River State,Nigeria     

Titus E. Amalu  Anim O. Ajake  Patrick O. Obi 《GeoJournal》2016,81(3):475-487

The purpose of the study was to examine the extent to which royalties generated from forest resources contributed to community development in Boki Local Government area of Cross River State, Nigeria. The study used questionnaire survey of house-hold heads and Interview with focus groups to obtain data for this study. A total of 224 household heads representing 20 % of the available house-hold heads in the area was used for the study. The data collected were presented using tables and charts while an inferential statistics (Pearson’s Product Moment correlation) was employed to test the hypothesis of the study. The result of the analysis revealed that there exist a positive correlation coefficient of 0.911 which indicates a strong and positive relationship between royalties collected from forest resources and the number of developmental projects in the study area. Based on the findings of this study, it was recommended that more efforts be directed towards the monitoring and regulation of forest resource exploration activities in the area to ensure that royalties collected are directed towards the establishment of more developmental projects in the area so as to impact more positively on the living standard of the people.  相似文献   

Geocrowdsourcing and accessibility for dynamic environments     

Han Qin  Rebecca M. Rice  Sven Fuhrmann  Matthew T. Rice  Kevin M. Curtin  Eric Ong 《GeoJournal》2016,81(5):699-716

  相似文献   

Spatial and temporal variations in rainfall over Darwin and its vicinity during different large-scale environments     

Surendra P. Rauniyar  Kevin J. E. Walsh 《Climate Dynamics》2016,46(3-4):671-691

  相似文献   

Intra-community implications of implementing multiple tsunami-evacuation zones in Alameda,California     

Jeff Peters  Nathan Wood  Rick Wilson  Kevin Miller 《Natural Hazards》2016,80(2):975-995

  相似文献   

Identification of hydrochemical facies in the Roswell Artesian Basin,New Mexico (USA), using graphical and statistical methods     

Brent D. Newman  Kay C. Havenor  Patrick Longmire 《Hydrogeology Journal》2016,24(4):819-839

Analysis of groundwater chemistry can yield important insights about subsurface conditions, and provide an alternative and complementary method for characterizing basin hydrogeology, especially in areas where hydraulic data are limited. More specifically, hydrochemical facies have been used for decades to help understand basin flow and transport, and a set of facies were developed for the Roswell Artesian Basin (RAB) in a semi-arid part of New Mexico, USA. The RAB is an important agricultural water source, and is an excellent example of a rechargeable artesian system. However, substantial uncertainties about the RAB hydrogeology and groundwater chemistry exist. The RAB was a great opportunity to explore hydrochemcial facies definition. A set of facies, derived from fingerprint diagrams (graphical approach), existed as a basis for testing and for comparison to principal components, factor analysis, and cluster analyses (statistical approaches). Geochemical data from over 300 RAB wells in the central basin were examined. The statistical testing of fingerprint-diagram-based facies was useful in terms of quantitatively evaluating differences between facies, and for understanding potential controls on basin groundwater chemistry. This study suggests the presence of three hydrochemical facies in the shallower part of the RAB (mostly unconfined conditions) and three in the deeper artesian system of the RAB. These facies reflect significant spatial differences in chemistry in the basin that are associated with specific stratigraphic intervals as well as structural features. Substantial chemical variability across faults and within fault blocks was also observed.  相似文献