Surface measurements of carbon dioxide and methane at Alert during an Arctic haze event in April, 1986     

Neil B. A. Trivett  Douglas E. J. Worthy  Kenneth A. Brice 《Journal of Atmospheric Chemistry》1989,9(1-3):383-397

Carbon dioxide (CO₂) has been measured at Alert by grab flask sampling since 1975 as part of the World Meteorological Organization's Background Air Pollution Monitoring Program. Deviations of CO₂ concentration from the mean annual cycle have previously been attributed to air masses arriving at Alert from the source regions of the industrialized parts of Europe and the Soviet Union. In situ measurements of ambient CO₂ and methane (CH₄) were made at Alert using an automated gas chromatograph, as part of the Arctic Haze Study during April 1986. The temporal behaviour of CO₂ and CH₄ during this period was found to be highly correlated with measurements of particulate sulphate and other atmospheric trace species of anthropogenic origin. Examination of calculated air mass back-trajectories provided further evidence that the observed short-term increases in CO₂ and CH₄ mixing ratios were due to long-range transport from anthropogenic source regions.  相似文献   

Mapping Recharge Areas Using a Ground-Water Flow Model – A Case Study     

Mary W. Stoertz  Kenneth R. Bradbury 《Ground water》1989,27(2):220-228

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Concentration fluctuation measurements in a plume dispersing in a stable surface layer     

Kenneth R. Mylne 《Boundary-Layer Meteorology》1992,60(1-2):15-48

A set of tracer experiments studying concentration fluctuations in a pollutant plume dispersing near the surface in a stably stratified nocturnal boundary layer is described, and the results are compared with those obtained in near-neutral stability conditions by Mylne and Mason (1991). The results highlight the importance of slow meandering of the plume which is characteristic of stable conditions. This meandering makes it impossible to conduct experiments under near-stationary conditions, resulting in considerable statistical variability in the results, but is important in reducing time-averaged concentrations. Spectral characteristics of the plume and general fluctuation statistics are qualitatively similar to those in near-neutral stability, but there are significant quantitative differences. Fluctuation time scales are shown to be substantially longer under stable conditions. This difference cannot be fully explained by the reduced windspeed alone, indicating that the length scale of plume elements is also longer. Some of the differences observed in stable conditions, particularly the longer time scales, are shown to substantially increase the potential hazard due to fluctuations in practical applications. A conceptual model of plume dispersion is described, which explains the observed plume structure under different conditions by relating it to the turbulent velocity spectra.  相似文献   

Sea surface wind stress and drag coefficients: The hexos results   总被引：17，自引：1，他引：17  

Stuart D. Smith  Robert J. Anderson  Wiebe A. Oost  C. Kraan  Nico Maat  Janice De Cosmo  Kristina B. Katsaros  Kenneth L. Davidson  Karl Bumke  Lutz Hasse  Helen M. Chadwick 《Boundary-Layer Meteorology》1992,60(1-2):109-142

Turbulent fluxes have been measured in the atmospheric surface layer from a boom extending upwind from the Dutch offshore research platform Meetpost Noordwijk (MPN) during HEXMAX (Humidity Exchange over the Sea Main Experiment) in October–November, 1986. We started out to study eddy flux of water vapour, but discrepancies among simultaneous measurements made with three different anemometers led us to develop methods to correct eddy correlation measurements of wind stress for flow distortion by nearby objects. We then found excellent agreement among the corrected wind stress data sets from the three anemometers on the MPN boom and with eddy correlation measurements from a mast on a tripod. Inertial-dissipation techniques gave reliable estimates of wind stress from turbulence spectra, both at MPN and at a nearby ship. The data cover a range of wave ages and the results yield new insights into the variation of sea surface wind stress with sea state; two alternative formulas are given for the nondimensional surface roughness as a function of wave age.  相似文献   

Surface currents and equatorial thermocline in a coupled upper ocean-atmosphere GCM     

Kenneth R Sperber  Sultan Hameed  W Gates Lawrence 《Climate Dynamics》1992,7(3):121-131

The Oregon State University coupled upper ocean-atmosphere GCM is evaluated in terms of the simulated winds, ocean currents and thermocline depth variations. Although the zonal wind velocities in the model are underestimated by a factor of about three and the zonal current velocities are underestimated by a factor of about five, the model is seen to qualitatively simulate the major features of the gyral scale currents, and the phases of the seasonal variation of the principal equatorial currents are in reasonable agreement with observations. The simulated tropical currents are dominated by Ekman transport and the eastern boundary currents do not penetrate far enough equatorward, while the western boundary currents do not penetrate far enough poleward. The subtropical trade wind belt and the mid-latitude westerlies are displaced equatorward of observations; hence, the mid-latitude eastward currents, principally the Kuroshio-North Pacific Drift and the Gulf Stream-North Atlantic Current are displaced equatorward. In spite of these shortcomings the surface current simulation of this two-layer upper ocean model is comparable with that of other ocean GCMs of coarse resolution. The coupled model successfully simulates the deepening of the thermocline westward across Pacific as a consequence of the prevailing Walker circulation. The region of most intense simulated surface forcing is located in the western Pacific due to a southwestward displacement of the northeast trade winds relative to observations; hence the equatorial Pacific is dominated by eastward propagation of thermocline depth variations. The excessively strong Ekman divergence and upwelling in the western Pacific cools the local warm pool, while incorrectly simulated westerlies in the eastern Pacific suppress upwelling and inhibit cooling from below. These features reduce the simulated trans-Pacific sea-surface temperature gradient, weakening the Walker circulation and the anomalies associated with the simulated Southern Oscillation. Offprint requests to: KR Sperber  相似文献   

Evaluating the environmental risks associated with the use of chromated copper arsenate-treated wood products in aquatic environments     

Kenneth M. Brooks 《Estuaries and Coasts》1996,19(2):296-305

Chromated copper arsenate (CCA)-treated wood has been used worldwide since 1933. In properly fixed wood, the chromium, copper, and arsenic are tightly bound to the wood fibers. However, it has long been known that small amounts of these metals do leach from properly treated wood products. These metals, particularly the cupric ion (Cu²⁺), are known to be highly toxic to aquatic organisms at concentrations as low as 6 μg Cu l^?1. The United States Environmental Protection Agency has established a marine water quality standard of 2.9 μg Cu l^?1 total copper. Washington State has established a marine water quality standard of 2.5 μg Cu l^?1 and a marine sediment standard of 390 mg Cu g^?1 (dry sediment). Comparison of these standards with the results of bioassays suggests that these levels are sufficiently low to protect even the most sensitive organisms. Metal losses are an inverse function of time and decline to background levels within 60–90 d of treated wood immersion. Increasing use of CCA-treated wood to construct residential bulkheads in estuarine environments on the east coast of the United States has raised concerns regarding the near-term environmental risks associated with these uses. This paper reports the development of a spreadsheet-based computer model to predict water column and sediment concentrations of copper leached from bulkheads and piling. Model output is compared with data in Weis et al. (1991, 1993) and Weis and Weis (1992). The model predicts environmental levels of copper that are highly dependent on input parameters but below regulatory levels for most projects constructed in reasonably well-circulated bodies of water. The model does demonstrate the possibility of exceeding regulatory standards for up to 3 wk when bulkheads are installed in very poorly flushed aquatic environments or where the surface area of the CCA-treated wood structure is a significant proportion of the water body surface area.  相似文献   

Patterns of seasonal availability and habitat use by fishes and decapod crustaceans in a southern New Jersey estuary     

Stephen T. Szedlmayer  Kenneth W. Able 《Estuaries and Coasts》1996,19(3):697-709

We examined the community structure of fish and selected decapod crustaceans and tested for within estuary differences among habitats at depths of 0.6 m to 7.9 m, in Great Bay and Little Egg Harbor in southern New Jersey. Several habitat types were identified a priori (e.g., eelgrass, sea lettuce, and marsh creeks) and sampled by trawl (4.9 m headrope, 19-mm mesh wings, 6.3-mm mesh liner), monthly, from June 1988 through October 1989. Repetitive (n=4) 2-min trawl tows were taken at each habitat type from 13 locations. The fishes and decapod crustaceans collected were typical of other Mid-Atlantic Bight estuaries but varied greatly inseasonal abundance and species. In the years sampled, bay anchovy (Anchoa mitchilli) was the dominant species (50.5% of the total number), followed by spot (Leiostomus xanthurus) (10.7%), Atlantic silverside (Menidia menidia) (9.7%), fourspine stickleback (Apeltes quadracus) (5.9%), blue crab (Callinectes sapidus) (4.6%), and northern pipefish (Syngnathus fuscus) (4.2%). The biota were examined by multi-dimensional scaling (MDS) for habitat associations and “best abiotic predictor” of community structure. Percent silt combined with salinity was the most important abiotic determinant of the faunal distributions among habitats. Temperature was a major factor influencing seasonal occurrence of the biota but had less effect on habitat comparisons. The analysis confirmed the distinct nature of the assemblages associated with the habitats, that is, eelgrass, upper estuary subtidal creeks, channels, and open bay areas. Several species were associated with specific habitats: for example,A. quadracus andS. fuscus with eelgrass, clupeids with subtidal creek stations,L. xanthurus with marsh channels, and black sea bass (Centropristis striata) and spotted hake (Urophycis regia) with sponge-peat habitat. Species richness appeared to be positively related to habitat structural heterogeneity. Thus, the best predictors for these estuarine fish and decapod crustacean assemblages were seasonal temperature, percent silt and salinity combined, and the physical heterogeneity of the habitat.  相似文献   

Isotropic and deviatoric characterization of the Coalora nuclear explosion in Yucca Flats     

Brian W. Stump  Robert E. Reinke  Kenneth H. Olsen  Lane R. Johnson 《Geophysical Journal International》1994,116(3):538-552

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Diel variation in immigration of fishes and decapod crustaceans to artificial seagrass habitat     

Susan M. Sogard  Kenneth W. Able 《Estuaries and Coasts》1994,17(3):622-630

Fish and decapod entry into small (1.5 m²) artificial seagrass habitats positioned on an open sand area in a New Jersey estuary was examined to determine if immigration varied between day and night. To encounter the structured habitats, colonizers had to cross an expanse of bare sand, with its presumably higher predation risk. Contrasts in abundance in the artificial seagrass plots between dawn and dusk indicated higher nighttime immigration for four species, including the fishesFundulus heteroclitus andMyoxocephalus aenaeus, and the caridean shrimpsPalaemonetes vulgaris andHippolyte pleuracanthus. Size-frequency distributions of colonizers varied between day and night for two fish species,Menidia menidia andSyngnathus fuscus, with a greater proportion of smaller individuals immigrating to the artificial seagrass at night.Callinectes sapidus also displayed a diel contrast in size distribution but, for this species, proportionately more small individuals colonized the plots during the day. We suggest that diel variability in predation risk and/or diel patterns in motor activity may be responsible for these patterns in immigration.  相似文献   

Comments on “Nd−Sr isotopic compositions of lower crustal xenoliths-Evidence for the origin of mid-Tertiary felsic volcanics in Mexico” by J. Ruiz,P.J. Patchett,and R.J. Arculus     

Kenneth L. Cameron  James V. Robinson 《Contributions to Mineralogy and Petrology》1990,104(5):609-614

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