澳大利亚气象研究中心的轨迹计算及其应用     

G. A. Mills  吴宝俊 《气象》1994,20(1):3-8

从天气分析和预报提供的后向轨迹信息可以加强预报指导。澳大利亚气象研究中心（ＢＭＲＣ）开发了一个计算三维后向和前向轨迹的软件，使用的资料是澳大利亚气象局有限区域３６小时３个风速分量的业务预报。它们有三种可用的输出形式；后向轨迹、前向轨迹及３６小时气块垂直位移等值线场。这个软件已用于分析诊断研究。  相似文献   

Diel patterns in coastal‐stream nitrate concentrations linked to evapotranspiration in the riparian zone of a low‐relief,agricultural catchment          下载免费PDF全文

Samuel A. Flewelling  George M. Hornberger  Janet S. Herman  Aaron L. Mills  Wendy M. Robertson 《水文研究》2014,28(4):2150-2158

Evapotranspiration (ET) can cause diel fluctuations in the elevation of the water table and the stage in adjacent streams. The diel fluctuations of water levels change head gradients throughout the day, causing specific discharge through near‐stream sediment to fluctuate at the same time scale. In a previous study, we showed that specific discharge controls the residence time of groundwater in streambed sediment that, in turn, exerted the primary control on removal from groundwater passing through the streambed. In this study, we examine the magnitude of diel specific discharge patterns through the streambed driven by ET in the riparian zone with a transient numerical saturated–unsaturated groundwater flow model. On the basis of a first‐order kinetic model for removal, we predicted diel fluctuations in stream concentrations. Model results indicated that ET drove a diel pattern in specific discharge through the streambed and riparian zone (the removal zones). Because specific discharge is inversely proportional to groundwater travel time through the removal zones and travel time determines the extent of removal, diel changes in ET can result in a diel pattern in concentration in the stream. The model predictions generally matched observations made during summertime base‐flow conditions in a small coastal plain stream in Virginia. A more complicated pattern was observed following a seasonal drawdown period, where source components to the stream changed during the receding limb of the hydrograph and resulted in diel fluctuations being superimposed over a multi‐day trend in concentrations. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

Modelling vertical error in LiDAR-derived digital elevation models     

Fernando J. Aguilar  Jon P. Mills  Jorge Delgado  Manuel A. Aguilar  J.G. Negreiros  José L. Pérez 《ISPRS Journal of Photogrammetry and Remote Sensing》2010,65(1):103-110

  相似文献   

Development of Iron Speciation Reference Materials for Palaeoredox Analysis     

Lewis J. Alcott  Alexander J. Krause  Emma U. Hammarlund  Christian J. Bjerrum  Florian Scholz  Yijun Xiong  Andrew J. Hobson  Lesley Neve  Benjamin J. W. Mills  Christian Mrz  Bernhard Schnetger  Andrey Bekker  Simon W. Poulton 《Geostandards and Geoanalytical Research》2020,44(3):581-591

The development and application of geochemical techniques to identify redox conditions in modern and ancient aquatic environments has intensified over recent years. Iron (Fe) speciation has emerged as one of the most widely used procedures to distinguish different redox regimes in both the water column and sediments, and is the main technique used to identify oxic, ferruginous (anoxic, Fe(II) containing) and euxinic (anoxic, sulfidic) water column conditions. However, an international sediment reference material has never been developed. This has led to concern over the consistency of results published by the many laboratories that now utilise the technique. Here, we report an interlaboratory comparison of four Fe speciation reference materials for palaeoredox analysis, which span a range of compositions and reflect deposition under different redox conditions. We provide an update of extraction techniques used in Fe speciation and assess the effects of both test portion mass, and the use of different analytical procedures, on the quantification of different Fe fractions in sedimentary rocks. While atomic absorption spectroscopy and inductively coupled plasma‐optical emission spectrometry produced comparable Fe measurements for all extraction stages, the use of ferrozine consistently underestimated Fe in the extraction step targeting mixed ferrous–ferric minerals such as magnetite. We therefore suggest that the use of ferrozine is discontinued for this Fe pool. Finally, we report the combined data of four independent Fe speciation laboratories to characterise the Fe speciation composition of the reference materials. These reference materials are available to the community to provide an essential validation of in‐house Fe speciation measurements.  相似文献   

Quantification of TCE Co‐Oxidation in Groundwater Using a 14C–Assay          下载免费PDF全文

James C. Mills IV  John T. Wilson  Barbara H. Wilson  Todd H. Wiedemeier  David L. Freedman 《Ground Water Monitoring & Remediation》2018,38(2):57-67

Bacteria that degrade natural organic matter in groundwater contain oxygenase enzymes that can co‐oxidize trichloroethene (TCE). This degradation pathway is promising for large dilute plumes, but its evaluation is limited because the density of the bacteria with oxygenase enzymes has not been correlated to field scale rates of degradation. A ¹⁴C–TCE assay was developed to determine pseudo first‐order rate constants for the aerobic co‐oxidation of TCE in groundwater. The assay involved incubating ¹⁴C–TCE in samples of groundwater contained in 160 mL serum bottles, and monitoring the accumulation of radiolabel in degradation products. A first‐order rate constant for co‐oxidation was extracted from the rate of accumulation of ¹⁴C in products, accounting for volumetric changes in the serum bottles due to sampling and subsequent changes to the distribution of TCE between the aqueous and gaseous phases. Of the groundwater samples evaluated from 19 wells at five sites, eight samples at three sites had ¹⁴C product accumulation rates that exceeded the accumulation rate in filter‐sterilized groundwater controls. First‐order rate constants ranged from 2.65 to 0.0066 year^?1, which is equivalent to half‐lives of 0.26 to 105 years. Groundwater samples from a few of the wells in which co‐oxidation occurred had volatile organic contaminants in addition to TCE; their presence may have induced the oxygenase enzymes that are needed for TCE co‐oxidation. ¹⁴CO₂ represented ~37% to 97% of the ¹⁴C products that accumulated; the balance of the products was soluble and non‐volatile.  相似文献   

Re-evaluation of Rostraria bierii Tokioka, 1970 (Annelida) from Seto,Japan as a magelonid,with a review of the Magelonidae of the western Pacific     

Mortimer Kate  Mills Kimberley  Gil Jo?o 《海洋学报(英文版)》2022,41(3):61-69

  相似文献   

Spatial and temporal distribution of chromophoric dissolved organic matter (CDOM) fluorescence and its contribution to light attenuation in UK waterbodies   总被引：3，自引：0，他引：3  

J. Foden  D.B. Sivyer  D.K. Mills  M.J. Devlin   《Estuarine, Coastal and Shelf Science》2008,79(4):707-717

Vertical attenuation of light through the water column (K_d) is attributable to the optically active components of phytoplankton, suspended particulate material (SPM) and chromophoric dissolved organic matter (CDOM). Of these, CDOM is not routinely monitored and was the main focus of this study. Concentrations and spatio-temporal patterns of CDOM fluorescence were investigated between August 2004 and March 2006, to quantify the correlation coefficient between CDOM and salinity and to better characterise the contribution of CDOM to K_d. Sampling was conducted at a broad range of UK and Republic of Ireland locations; these included more than 15 estuaries, 30 coastal and 70 offshore sites in the southern North Sea, Irish Sea, Liverpool Bay, Western Approaches and the English Channel.An instrument package was used; a logger with multi-sensor array was deployed vertically through the water column and concurrent water samples were taken to determine salinity, CDOM fluorescence and SPM. Surface CDOM fluorescence values ranged between 0.05 and 16.80 S.Fl.U. (standardised fluorescence units). A strong, negative correlation coefficient of CDOM to salinity (r² = 0.81) was found. CDOM absorption (aCDOM_λ) was derived from fluorescence measurements and was in the range 0.02–2.2 m⁻¹ with mean 0.15 m⁻¹. These results were comparable with direct measurements of aCDOM_λ in the same geographic regions, as published by other workers.Spatial differences in CDOM fluorescence were generally explicable by variation in salinity, in local conditions or catchment areas; e.g. CDOM at the freshwater end was 3.54–11.30 S.Fl.U., reflecting the variety of rivers sampled and their different catchments. Temporal changes in CDOM fluorescence were related to salinity. A significant and positive correlation was found between CDOM and K_d, and although CDOM was found to be less influential than SPM on K_d, it was still of significance particularly in coastal and offshore waters of lower turbidity.  相似文献   

An updated assessment of lightning-related fatality and injury risk in Canada: 2002–2017     

Mills  Brian 《Natural Hazards》2020,102(3):997-1009

Cloud-to-ground lightning is a common and dangerous natural atmospheric hazard in southern Canada. Previous research conducted by the author and colleagues, using data from 1994 to 2003, estimated that lightning directly or indirectly kills 9–10 people and injures 92–164 more each year in Canada. Repeating the analysis using data from the same government agency and media sources for the 2002–2017 period, the author found that lightning-related mortality decreased to 2–3 deaths per year, roughly 0.08 deaths per million population. An average of 180 lightning-related injuries each year (5.3 per million population) was estimated for the same period, slightly greater than the maximum documented in the 1994–2003 analysis. About half of the drop in mortality between periods may be attributed to the reduction in reported deaths associated with lightning-ignited municipal fires since 2000. The remainder may be due to a combination of greater availability and use of communication technology, faster emergency response and medical treatment, and increased public awareness of lightning hazards and safety. Further research is required to explain why lightning-related injury rates have remained stable; better understand the interaction of technological, behavioral and other factors; and to determine the efficacy of past and potential future safety interventions.

  相似文献   

The Irish Sea: Is it eutrophic?     

R.J. Gowen  P. Tett  K. Kennington  D.K. Mills  T.M. Shammon  B.M. Stewart  N. Greenwood  C. Flanagan  M. Devlin  A. Wither 《Estuarine, Coastal and Shelf Science》2008

The question of whether the Irish Sea is eutrophic is addressed by reviewing the evidence for anthropogenic nutrient enrichment, elevated phytoplankton production and biomass and undesirable disturbance in the context of the EU and OSPAR definitions of eutrophication. Winter concentrations of dissolved available inorganic phosphate (DAIP), nitrogen (DAIN as nitrate and nitrite) and silicate (Si) in coastal waters and concentrations of DAIP and Si in offshore waters of the Irish Sea are elevated relative to winter Celtic Sea shelf break concentrations (0.5 μM DAIP, 7.7 μM DAIN and 2.7 μM Si). Significant, negative nutrient salinity relationships and analysis of the Isle of Man nutrient time-series indicate that the elevated Irish Sea levels of DAIP and DAIN are the result of anthropogenic enrichment with highest concentrations (≈2.0 μM DAIP, 30 μM DAIN and 17 μM Si) measured in near shore eastern Irish Sea waters.  相似文献   

Comparison of Two Computational Methods for Estimating Transmissivity Based on the Picking Equation     

A. Mills 《Ground water》2020,58(5):813-821

A comparison is presented of two computational methods, PICKINGmodel and PPC-Recovery, to estimate transmissivities based on the Picking equation using water-level recovery data from brief pumping tests of relatively low-yielding domestic wells. The tests were performed by the United States Geological Survey (USGS) in 50 domestic bedrock wells in south-central New York State, and USGS staff performed the analysis using PICKINGmodel based on the Picking equation. The results indicated that the estimated transmissivities ranged from 0.86 to 2900 ft²/d (0.080 to 270 m²/d) with a median of 41 ft²/d (3.8 m²/d). The same data were later analyzed using PPC-Recovery also based on the Picking equation. The two sets of estimated transmissivities were compared and statistically had the same median value at a probability of 95%. In another analysis, the PPC-Recovery method was applied to the same data that had been truncated at the point when the slope of the recovery data curve began to deviate from a straight line aligned with the middle portion of the recovery data. Comparing these resulting estimates of transmissivity with values originally obtained using the PICKINGmodel, the two had statistically the same median value for transmissivity at a probability of 95%. It was concluded that using PPC-Recovery in this manner to estimate transmissivity in low-yielding domestic wells will yield transmissivity values sufficiently close to the results had PICKINGmodel been used, and with less time and effort.  相似文献