When we don't know the costs or the benefits: Adaptive strategies for abating climate change   总被引：1，自引：2，他引：1  

Robert J. Lempert  Michael E. Schlesinger  Steve C. Bankes 《Climatic change》1996,33(2):235-274

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Earthquakes: prediction and the media—a case study in public understanding of science     

Steve Miller 《Geophysical Journal International》1997,131(3):530-533

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Assessment of a juvenile and trash excluder device in a Vietnamese shrimp trawl fishery     

Eayrs  Steve; Hai  Nguyen Phong; Ley  Janet 《ICES Journal of Marine Science》2007,64(8):1598-1602

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Remote sensing of sea surface temperature and chlorophyll during Lagrangian experiments at the Iberian margin     

Tim J. Smyth  Peter I. Miller  Steve B. Groom  Samantha J. Lavender 《Progress in Oceanography》2001,51(2-4)

Satellite derived sea surface temperature (SST) and chlorophyll data are used to characterise the period of upwelling during a cruise on which two Lagrangian drift experiments were conducted off the Iberian Atlantic coast in August 1998. During the cruise there was a prolonged period of equator-ward winds which favour upwelling; three distinct maxima were observed in the meteorological data interspersed with periods of relaxation. The SST and chlorophyll imagery show upwelling to be active with distinct offshore filaments that are cooler and of higher chlorophyll concentration than the surrounding oceanic water; these filaments represent an important cross-shelf transport mechanism. A front detection methodology has been applied to satellite images and suggests that these filaments are distinct, long-lived features, characterised by enhanced primary production.  相似文献   

Use of Cell-Specific PAM-Fluorometry to Characterize Host Shading in the Epiphytic Dinoflagellate Gambierdiscus toxicus   总被引：1，自引：0，他引：1  

Tracy A. Villareal  & Steve L. Morton 《Marine Ecology》2002,23(2):127-140

Abstract. Cell‐specific fluorescence characteristics were used to characterize the light tolerance of the toxic benthic dinoflagellate Gambierdiscus toxicus. The fluorescence parameter F_v : F_m was measured using pulse amplitude modulation (PAM) fluorometry on individual cells collected from foliose red algae growing in the sub‐tidal margin of South Water Cay, Belize. Samples were collected over several days during sunny and cloudy conditions and compared to samples incubated in situ. The data from individual cells were used to generate both F_v : F_m frequency histograms and averages. Maximum individual cell values of F_v : F_m reached 0.81 in pre‐dawn samples, a value near the theoretical maximum for PAM fluorometry. In field samples from macroalgal hosts, average F_v : F_m values declined only slightly during the day, but cells incubated in bottles under 47 % incident sunlight showed a significant mid‐day depression. In freshly collected samples, near‐maximum F_v : F_m values could be found in individual cells during the entire day; however, the frequency histograms indicated a greater range in F_v : F_m values during the afternoon than in the morning. In contrast, cultures of G. toxicus showed a tight distribution around a mean. Field samples showed a rapid recovery to near‐maximum F_v : F_m within 2 min when assayed using a standardized actinic light series. Similar results were obtained in laboratory cultures of G. toxicus grown at 73 µmol photons · m^‐2 · s^‐1, but not at 383 µmol photons · m^‐2 · s^‐1. These data provide empirical support for suggestions that G. toxicus exploits the three‐dimensional structure of the algal host thallus to minimize light exposure. This strategy permits G. toxicus, a high‐light intolerant species in culture, to thrive in shallow, well‐lit tropical seas. It may also partially explain the observed preference of G. toxicus for complex, foliose macroalgae as hosts.  相似文献   

Stabilisation of the Stanton Lees Landslip Using an Embedded Pile Retaining Wall     

Steve J. Hodgetts  Brendan C. O’Kelly  Matthew J. Raybould 《Geotechnical and Geological Engineering》2007,25(6):705-715

A landslip occurred near the village of Stanton Lees, Derbyshire, UK, in November 2000 following a prolonged period of heavy rainfall. The slip resulted in the gradual, progressive down-slope movement of a steep embankment that was supporting an existing gabion retaining wall and a minor road which was subsequently closed to vehicular traffic. This paper describes the site; the sequence of events leading up to the start of the landslide; an interpretation of the ground conditions and onsite monitoring data; and the engineering works carried out in order to stabilise the slip and return the road to serviceability. The landslip occurred due to the superficial deposits moving over the weathered bedrock after the groundwater levels had been elevated following a prolonged period of heavy rainfall. A stability analysis indicated that the embankment was at a state of limiting equilibrium and its factor of safety on slope instability was found to be particularly sensitive to fairly minor changes in the groundwater levels. The remedial works replaced the existing gabion wall with a new cantilevered, bored pile retaining wall that comprised two rows of piles (600-mm in diameter), which were staggered in plan arrangement.  相似文献   

锚杆锚固体系中的波系特征研究     

张世平  张昌锁  王成  ZOU Steve 《岩土力学》2007,28(12):2570-2573

采用凝固过程中的混凝土模拟不同物理力学特性的锚固介质,用数值模拟和试验的方法研究了锚固锚杆中的波系及锚固锚杆中界面波的形成过程。数值模拟和试验模拟都表明随着锚固介质力学性质的改变锚杆中传播的波的特性发生改变。锚杆中传播的P波对锚固介质的力学特性非常敏感,随着锚固强度的增加,界面波产生,P波逐渐衰减消失。锚杆中传播的波由原来的P波占主导成为界面波占主导,波在锚固段的传播速度也由杆速度成为界面波波速。界面波的波速与锚固介质的力学性质相关,因此可以用界面波的波速来评价锚杆锚固质量以及计算锚杆锚固段长度。  相似文献   

The role of terrestrial snow cover in the climate system   总被引：2，自引：0，他引：2  

Steve Vavrus 《Climate Dynamics》2007,29(1):73-88

Snow cover is known to exert a strong influence on climate, but quantifying its impact is difficult. This study investigates the global impact of terrestrial snow cover through a pair of GCM simulations run with prognostic snow cover and with all snow cover on land eliminated (NOSNOWCOVER). In this experiment all snowfall over land was converted into its liquid–water equivalent upon reaching the surface. Compared with the control run, NOSNOWCOVER produces mean-annual surface air temperatures up to 5 K higher over northern North America and Eurasia and 8–10 K greater during winter. The globally averaged warming of 0.8 K is one-third as large as the model’s response to 2 × CO₂ forcing. The pronounced surface heating propagates throughout the troposphere, causing changes in surface and upper-air circulation patterns. Despite the large atmospheric warming, the absence of an insulating snow pack causes soil temperatures in NOSNOWCOVER to fall throughout northern Asia and Canada, including extreme wintertime cooling of over 20 K in Siberia and a 70% increase in permafrost area. The absence of snow melt water also affects extratropical surface hydrology, causing significantly drier upper-layer soils and dramatic changes in the annual cycle of runoff. Removing snow cover also drastically affects extreme weather. Extreme cold-air outbreaks (CAOs)—defined relative to the control climatology—essentially disappear in NOSNOWCOVER. The loss of CAOs appears to stem from both the local effects of eliminating snow cover in mid-latitudes and a remote effect over source regions in the Arctic, where −40°C air masses are no longer able to form.  相似文献   

Defining probability of saturation with indicator kriging on hard and soft data     

Steve W. Lyon  Arthur J. Lembo Jr.  M. Todd Walter  Tammo S. Steenhuis 《Advances in water resources》2006

In humid, well-vegetated areas, such as in the northeastern US, runoff is most commonly generated from relatively small portions of the landscape becoming completely saturated, however, little is known about the spatial and temporal behavior of these saturated regions. Indicator kriging provides a way to use traditional water table data to quantify probability of saturation to evaluate predicted spatial distributions of runoff generation risk, especially for the new generation of water quality models incorporating saturation excess runoff theory. When spatial measurements of a variable are transformed to binary indicators (i.e., 1 if above a given threshold value and 0 if below) and the resulting indicator semivariogram is modeled, indicator kriging produces the probability of the measured variable to exceed the threshold value. Indicator kriging gives quantified probability of saturation or, consistent with saturation excess runoff theory, runoff generation risk with depth to water table as the variable and the threshold set near the soil surface. The probability of saturation for a 120 m × 180 m hillslope based upon 43 measurements of depth to water table is investigated with indicator semivariograms for six storm events. The indicator semivariograms show high spatial structure in saturated regions with large antecedent rainfall conditions. The temporal structure of the data is used to generate interpolated (soft) data to supplement measured (hard) data. This improved the spatial structure of the indicator semivariograms for lower antecedent rainfall conditions. Probability of saturation was evaluated through indicator kriging incorporating soft data showing, based on this preliminary study, highly connected regions of saturation as expected for the wet season (April through May) in the Catskill Mountain region of New York State. Supplementation of hard data with soft data incorporates physical hydrology of the hillslope to capture significant patterns not available when using hard data alone for indicator kriging. With the need for water quality models incorporating appropriate runoff generation risk estimates on the rise, this manner of data will lay the groundwork for future model evaluation and development.  相似文献   

Modelling the DC electrical response of fully and partially saturated Permo-Triassic sandstone     

Steve Taylor  Ron Barker 《Geophysical Prospecting》2006,54(3):351-367

Results from a laboratory investigation into the electrical properties of fully and partially saturated Wildmoor Triassic Sandstone have been modelled using the Archie, Waxman–Smits and Hanai–Bruggeman equations. The results demonstrate the limitation of using simple relationships to describe samples when the matrix resistivity ρ_r is not significantly greater than the saturating electrolyte resistivity ρ_w. In these situations Archie's parameters m and n are not accurately determined. Conversely, the more sophisticated Waxman–Smits and Hanai–Bruggeman models provide parameters that better describe the electrical properties of the rock and are able to identify heterogeneity between samples that would otherwise be missed. The ranges of values for matrix resistivity (49 < ρ_r < 161 Ωm) and cementation factor (1.6 < m < 2.1) obtained from the Hanai–Bruggeman model indicate significant variation between samples. Comparison of laboratory‐determined values for cation exchange capacity (0.06 < Q_v < 0.51 meq/mL) and those obtained from the Waxman–Smits model (0.09 < Q_v < 0.55 meq/mL) indicates a very strong correlation, suggesting this model is appropriate for describing the rock. There is good agreement between parameters modelled using fully and partially saturated versions of both the Hanai–Bruggeman and Waxman–Smits equations, indicating that the data are consistent with these models and that the assumptions made are appropriate.  相似文献