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1.
Katherine M. Papastephanou Stephen M. Bollens Anne M. Slaughter 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):3078
Cross-shelf distribution and abundance of copepod nauplii and copepodids were measured during three summer upwelling seasons (2000–2002) in a coastal upwelling zone off northern California. These 3 years varied considerably in the intensity of winds, abundance of chlorophyll, and water temperature. The cruises in 2000 were characterized by relaxation conditions, with generally high levels of chlorophyll and high water temperature. The cruises in 2001 and 2002 were dominated by strong and persistent upwelling events, leading to lower chlorophyll and water temperatures. The copepod assemblage was dominated by Oithona spp., Acartia spp. and Pseudocalanus spp., with Metridia pacifica (lucens), Microsetella rosea, Oncaea spp. and Tortanus discaudatus also common during all 3 years. The cross-shelf distribution of copepods was generally shifted offshore during upwelling and onshore during relaxation events, although some variability between species occurred. Abundance of all life stages generally exhibited a negative correlation with cross-shelf transport averaged over at least 1–4 days and lagged by 0–3 days, indicating lower abundances during and immediately after active upwelling. However, copepod nauplii seemed to respond positively to wind events lasting 1–5 days followed by a period of relaxation lasting 6 or 7 days. These rapid rates of change in abundance are probably too great to be due to in situ growth and reproduction alone; physical processes must also play a role. These results suggest a highly dynamic relationship between copepods and upwelling events off northern California, with species-specific responses to upwelling to be expected. 相似文献
2.
Reid Mark E. Godt Jonathan W. LaHusen Richard G. Slaughter Stephen L. Badger Thomas C. Collins Brian D. Schulz William H. Baum Rex L. Coe Jeffrey A. Harp Edwin L. Schmidt Kevin M. Iverson Richard M. Smith Joel B. Haugerud Ralph A. George David L. 《Landslides》2021,18(9):2993-3009
On 22 March 2014, a massive, catastrophic landslide occurred near Oso, Washington, USA, sweeping more than 1 km across the adjacent valley flats and killing 43 people. For the following 5 weeks, hundreds of workers engaged in an exhaustive search, rescue, and recovery effort directly in the landslide runout path. These workers could not avoid the risks posed by additional large-scale slope collapses. In an effort to ensure worker safety, multiple agencies cooperated to swiftly deploy a monitoring and alerting system consisting of sensors, automated data processing and web-based display, along with defined communication protocols and clear calls to action for emergency management and search personnel. Guided by the principle that an accelerating landslide poses a greater threat than a steadily moving or stationary mass, the system was designed to detect ground motion and vibration using complementary monitoring techniques. Near real-time information was provided by continuous GPS, seismometers/geophones, and extensometers. This information was augmented by repeat-assessment techniques such as terrestrial and aerial laser scanning and time-lapse photography. Fortunately, no major additional landsliding occurred. However, we did detect small headscarp failures as well as slow movement of the remaining landslide mass with the monitoring system. This was an exceptional response situation and the lessons learned are applicable to other landslide disaster crises. They underscore the need for cogent landslide expertise and ready-to-deploy monitoring equipment, the value of using redundant monitoring techniques with distinct goals, the benefit of clearly defined communication protocols, and the importance of continued research into forecasting landslide behavior to allow timely warning.
相似文献3.
Charles W. Slaughter 《国际泥沙研究》2000,(2)
lINTRODUCTIONRangeandforestlandsofnorthwesternNorthAmericahavebeenutilizedforres0urceextracti0nandproductionsinceinitialhuman0ccupationofthecontinent.Intensive"managed"utilizati0nofec0systemsforspecificbenefitsincludingcattle,sheep,t1sh,w00dandagriculturalpr0ductshasbeenong0ingfornearly0ne-and-haIfcenturies.Intensiveresourceproducti0nhasto0oftenbeenacc0mpaniedbyunwanted"sideeffects"includingacceleratederosion,s0illossandsedimentdeliveredoffsitetod0wnstreamlocati0ns,estuariesandoceanicsin… 相似文献
4.
The line-centre-magnetogram technique has been used to measure the average velocity in magnetic elements in plages and isolated magnetic elements (including dipoles) in Ca ii 8542, Mg i 5183, Fe i 8688 and C i 9111. The velocities vary from 0.6 km s–1 downflow in the line of deepest origin to zero in the highest. The smooth curve obtained by combining these with the results of other investigators is in conformity with Giovanelli's (1977) theory of inflow in the neighborhood of the temperature minimum.This material is based upon research supported by the National Science Foundation under its contract No. AST 74-04129 with the Association of Universities for Research in Astronomy, Inc., for management, operation and maintenance of the Kitt Peak National Observatory.Visiting Astronomer, Kitt Peak National Observatory. 相似文献
5.
On the utility of identification schemes for digital earth science data: an assessment and recommendations 总被引：1，自引：1，他引：0
Ruth E. Duerr Robert R. Downs Curt Tilmes Bruce Barkstrom W. Christopher Lenhardt Joseph Glassy Luis E. Bermudez Peter Slaughter 《Earth Science Informatics》2011,4(3):139-160
In recent years, a number of data identification technologies have been developed which purport to permanently identify digital
objects. In this paper, nine technologies and systems for assigning persistent identifiers are assessed for their applicability
to Earth science data (ARKs, DOIs, XRIs, Handles, LSIDs, OIDs, PURLs, URIs/URNs/URLs, and UUIDs). The evaluation used four
use cases that focused on the suitability of each scheme to provide Unique Identifiers for Earth science data objects, to
provide Unique Locators for the objects, to serve as Citable Locators, and to uniquely identify the scientific contents of
data objects if the data were reformatted. Of all the identifier schemes assessed, the one that most closely meets all of
the requirements for an Unique Identifier is the UUID scheme. Any of the URL/URI/IRI-based identifier schemes assessed could
be used for Unique Locators. Since there are currently no strong market leaders to help make the choice among them, the decision
must be based on secondary criteria. While most publications now allow the use of URLs in citations, so that all of the URL/URI/IRI
based identification schemes discussed in this paper could potentially be used as a Citable Locator, DOIs are the identification
scheme currently adopted by most commercial publishers. None of the identifier schemes assessed here even minimally address
identification of scientifically identical numerical data sets under reformatting. 相似文献
6.
Anne M. Slaughter Stephen M. Bollens Gretchen Rollwagen Bollens 《Deep Sea Research Part II: Topical Studies in Oceanography》2006,53(25-26):3099
Mesozooplankton (>200 μm) grazing impact (% phytoplankton standing crop consumed d−1) was determined by the gut fluorescence method during three springs (2000, 2001 and 2002) and two winters (2002 and 2003) in a coastal upwelling region off northern California. Wind events, in terms of both magnitude and duration, varied inter-annually and seasonally and included both upwelling-favorable and relaxation events. Grazing impact of mesozooplankton also varied inter-annually and seasonally, and was highest during June 2000 (mean=129% of standing crop d−1), a prolonged period of wind “relaxation” and phytoplankton bloom. In contrast, mean grazing impact was lower during periods of stronger, more persistent winds, more active upwelling, greater cross-shelf transport, and lower chlorophyll concentration (25% and 38% in May–June 2001 and 2002, respectively). Wintertime conditions (January 2002 and 2003) were characterized by weakly upwelling or downwelling-favorable winds, low chlorophyll concentration, and lower mean mesozooplankton grazing impact (13% and 12%, respectively). The larger (>500 μm) size class contributed proportionally more to total mesozooplankton (>200 μm) grazing impact than the smaller (200–500 μm) size class during all sampling periods except spring 2002. These results suggest that mesozooplankton grazing impact is higher in spring than in winter, and that during the spring upwelling season, grazing is higher during periods of wind relaxation (weak upwelling) than during periods of stronger upwelling. Further, these results suggest an important role of mesozooplankton grazers on phytoplankton dynamics in the upwelling region off northern California. 相似文献
7.
8.
The coefficients of third degree and fifth degree polynomial representations of limb darkening are tabulated for 50 wavelengths in the interval 7404-24 018.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.Summer Research Assistant at Kitt Peak National Observatory 1975. 相似文献
9.
Processing U ores in the JEB Mill of the McClean Lake Operation in northern Saskatchewan produces spent leaching solutions (raffinates) with pH 1.5, and As and Ni concentrations up to 6800 and 5200 mg L−1, respectively. Bench-scale neutralization experiments (pH 2–8) were performed to help optimize the design of mill processes for reducing As and Ni concentrations in tailings and raffinates to 1 mg L−1 prior to their disposal. Precipitate mineralogy determined by chemical analysis, XRD, SEM, EM, XM and EXAFS methods, included gypsum (the dominant precipitate), poorly crystalline scorodite (precipitated esp. from pH 2–4), annabergite, hydrobasaluminite, ferrihydrite, green rust II and theophrastite. The As was mostly in scorodite with smaller amounts in annabergite and trace As adsorbed and/or co-precipitated, probably by ferrihydrite. Geochemical modeling indicated that above pH 2, the ion activity product (IAP) of scorodite lies between the solubility products of amorphous and crystalline phases (log Ksp = −23.0 and −25.83, respectively). The IAP decreases with increasing pH, suggesting that the crystallinity of the scorodite increases with pH. Forward geochemical models support the assumption that during neutralization, particles of added base produce sharp local pH gradients and disequilibrium with bulk solutions, facilitating annabergite and theophrastite precipitation. 相似文献
10.
Joanna K. York George B. McManus Wim J. Kimmerer Anne M. Slaughter Toni R. Ignoffo 《Estuaries and Coasts》2014,37(3):576-588
We investigated trophic relationships involving microzooplankton in the low salinity zone of the San Francisco Estuary (SFE) as part of a larger effort aimed at understanding the dynamics of the food web supporting the endangered delta smelt, Hypomesus transpacificus. We performed 14 cascade experiments in which we manipulated the biomass of a copepod (Limnoithona tetraspina, Pseudodiaptomus forbesi, or Acartiella sinensis) and quantified responses of lower trophic levels including bacterioplankton, phytoplankton, and microzooplankton. Microzooplankton comprised a major food source for copepods; 9 out of 14 experiments showed removal of at least one group of microzooplankton by copepods. In contrast, the impact of copepods on phytoplankton was indirect; increased copepod biomass led to greater growth of phytoplankton in 3 of 14 experiments. Estimated clearance rates on microzooplankton were 4 mL day?1 for L. tetraspina and 2–6 mL day?1 for P. forbesi, whereas A. sinensis consumed mainly copepod nauplii. Complex trophic interactions, including omnivory, among copepods, microzooplankton, and different components of the phytoplankton likely obscured clear trends. The food web of the SFE is probably less efficient than previously thought, providing poor support to higher trophic levels; this inefficient food web is almost certainly implicated in the continuing low abundance of fishes, including the delta smelt that use the low salinity zone of the San Francisco Estuary. 相似文献