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51.
Edward J. Phlips Susan Badylak Mary C. Christman Margaret A. Lasi 《Estuaries and Coasts》2010,33(2):498-512
This paper describes the results of 10 years of water quality monitoring in the Indian River Lagoon Florida, with special
emphasis on the relationships between trends in climatic conditions and the distribution, composition, and abundance of the
phytoplankton community. The Indian River Lagoon, which spans 220 km of Florida’s east coast, is a region of particular concern
because of the rapid rate of human development throughout the region and the hydrologically restricted character of the lagoon,
which heightens the potential for algal bloom. Water sampling was carried out on a monthly to twice-monthly basis at six sites
located in the northern and central lagoon. The 10-year study included both extended periods of below and above average rainfall.
A number of ecologically distinct regions exist within the lagoon, which differ considerably in water exchange properties
and watershed inputs. The northern lagoon is characterized by longer water residence times, lower phosphorus concentrations,
higher nitrogen concentrations, and more stable salinity conditions than the central lagoon. Mean phytoplankton biovolumes
were substantially higher at the sites in the northern lagoon than at the sites in the central lagoon, and algal blooms were
more common and intense in the former region. Inter-annual patterns of phytoplankton biovolume were also different in the
northern and central lagoon. In the northern lagoon, phytoplankton biovolumes were lowest during the drought period, from
the autumn of 1998 to the spring of 2001. By contrast, algal bloom events in the central lagoon were not only less frequent
but were not tied to periods of high rainfall. The most widespread and common bloom formers were the potentially toxic dinoflagellate
Pyrodinium bahamense var. bahamense and two centric diatoms, Dactyliosolen fragilissimus and Cerataulina pelagica. Many of the biovolume peaks observed over the study period were attributable to these three species. The results of time
series modeling of phytoplankton dynamics further highlighted the disparities between the two regions of the lagoon in terms
of the suite of parameters that best predict the observed trends in the biomass of phytoplankton. Overall, the outcome of
this initial modeling effort in the Indian River Lagoon suggests that time series approaches can help define the factors that
influence phytoplankton dynamics. 相似文献
52.
We study the numerical approximation on irregular domains with general grids of the system of poroelasticity, which describes fluid flow in deformable porous media. The flow equation is discretized by a multipoint flux mixed finite element method and the displacements are approximated by a continuous Galerkin finite element method. First-order convergence in space and time is established in appropriate norms for the pressure, velocity, and displacement. Numerical results are presented that illustrate the behavior of the method. 相似文献
53.
Julien Léger Raphaël Pik Bouchaïb Tibari Sébastien Ternois Mary Ford Chantal Peiffert Julien Mercadier 《Geostandards and Geoanalytical Research》2023,47(2):219-242
The in situ (U-Th-Sm)/He and U/Pb laser-ablation double-dating procedure is a valuable method that can provide a large dataset relatively efficiently in contrast with conventional bulk helium thermochronometry. In this study, we evaluate the potential age error associated with the double ablation procedure and report the in situ (U-Th-Sm)/He double-ablation dating of 249 zircons from the Fish Canyon Tuff locality. With LA-ICP-MS pseudo-depth profiling and 3D numerical modelling, we show that the concentric double-ablation procedure in minerals with U-Th-Sm zoning can generate a significant (U-Th-Sm)/He age error (positive or negative), resulting in over-scattering and/or an offset of the mean age. Pseudo-depth profiling is insufficient to predict the individual age error, partly because of the superimposed ablations. To evaluate the consequence of this inherent bias, we confront a synthetic age distribution to the error expected for U-Th-Sm zoned zircons analysed with double-ablation (U-Th-Sm)/He thermochronometry. As expected, a strong age bias causes the spreading of peak ages, downgrading the original signal. Yet, the throughput of the ablation-based method can allow intra- and inter-sample peak age identification and comparison, and the coupling of (U-Th-Sm)/He and U/Pb ages extends our ability to deconvolute a multimodal age spectrum. 相似文献
54.
In this work, we measure the performance of the fixed stress split algorithm for the immiscible water-oil flow coupled with linear poromechanics. The two-phase flow equations are solved on general hexahedral elements using the multipoint flux mixed finite element method whereas the poromechanics equations are discretized using the conforming Galerkin method. We introduce a rigorous calculation of the update in poroelastic properties during the iterative solution of the coupled system equations. The effects of the coupling parameter on the performance of the fixed stress algorithm is demonstrated in two field studies: the Frio oil reservoir and the Cranfield injection site.
相似文献55.
56.
57.
Probabilistic estimates of future changes in California temperature and precipitation using statistical and dynamical downscaling 总被引:1,自引:0,他引:1
David W. Pierce Tapash Das Daniel R. Cayan Edwin P. Maurer Norman L. Miller Yan Bao M. Kanamitsu Kei Yoshimura Mark A. Snyder Lisa C. Sloan Guido Franco Mary Tyree 《Climate Dynamics》2013,40(3-4):839-856
Sixteen global general circulation models were used to develop probabilistic projections of temperature (T) and precipitation (P) changes over California by the 2060s. The global models were downscaled with two statistical techniques and three nested dynamical regional climate models, although not all global models were downscaled with all techniques. Both monthly and daily timescale changes in T and P are addressed, the latter being important for a range of applications in energy use, water management, and agriculture. The T changes tend to agree more across downscaling techniques than the P changes. Year-to-year natural internal climate variability is roughly of similar magnitude to the projected T changes. In the monthly average, July temperatures shift enough that that the hottest July found in any simulation over the historical period becomes a modestly cool July in the future period. Januarys as cold as any found in the historical period are still found in the 2060s, but the median and maximum monthly average temperatures increase notably. Annual and seasonal P changes are small compared to interannual or intermodel variability. However, the annual change is composed of seasonally varying changes that are themselves much larger, but tend to cancel in the annual mean. Winters show modestly wetter conditions in the North of the state, while spring and autumn show less precipitation. The dynamical downscaling techniques project increasing precipitation in the Southeastern part of the state, which is influenced by the North American monsoon, a feature that is not captured by the statistical downscaling. 相似文献
58.
Connecting atmospheric science and atmospheric models for aerocapture at Titan and the outer planets
Many atmospheric measurement systems, such as the sounding instruments on Voyager, gather atmospheric information in the form of temperature versus pressure level. In these terms, there is considerable consistency among the mean atmospheric profiles of the outer planets Jupiter through Neptune, including Titan. On a given planet or on Titan, the range of variability of temperature versus pressure level due to seasonal, latitudinal, and diurnal variations is also not large. However, many engineering needs for atmospheric models relate not to temperature versus pressure level but atmospheric density versus geometric altitude. This need is especially true for design and analysis of aerocapture systems. Drag force available for aerocapture is directly proportional to atmospheric density. Available aerocapture “corridor width” (allowable range of atmospheric entry angle) also depends on height rate of change of atmospheric density, as characterized by density scale height. Characteristics of hydrostatics and the gas law equation mean that relatively small systematic differences in temperature versus pressure profiles can integrate at high altitudes to very large differences in density versus altitude profiles. Thus, a given periapsis density required to accomplish successful aerocapture can occur at substantially different altitudes (∼150-300 km) on the various outer planets, and significantly different density scale heights (∼20-50 km) can occur at these periapsis altitudes. This paper will illustrate these effects and discuss implications for improvements in atmospheric measurements to yield significant impact on design of aerocapture systems for future missions to Titan and the outer planets. Relatively small-scale atmospheric perturbations, such as gravity waves, tides, and other atmospheric variations can also have significant effect on design details for aerocapture guidance and control systems. This paper will discuss benefits that would result from improved understanding of Titan and outer planetary atmospheric perturbation characteristics. Details of recent engineering-level atmospheric models for Titan and Neptune will be presented, and effects of present and future levels of atmospheric uncertainty and variability characteristics will be examined. 相似文献
59.
David L. Mary 《Journal of Astrophysics and Astronomy》2005,26(2-3):283-292
We provide a detailed introduction to the main problems arising when analyzing light curves in asteroseismology. Attention
is first paid to the signal model delivered by the pulsating stars and to the noise sources corrupting this model in photometric
observations. The main pitfalls and ambiguities occurring in Fourier analysis are summarized and illustrated. Some classical,
Least Squares (LS) based methods for spectrum analysis are analyzed and commented on from the point of view of ill-posed problems.
The insight that can be gained from such analyses is discussed. 相似文献
60.
Summary results from a pilot study conducted around an oil production platform on the Northwest Shelf of Australia 总被引:3,自引:0,他引:3
King SC Johnson JE Haasch ML Ryan DA Ahokas JT Burns KA 《Marine pollution bulletin》2005,50(11):1163-1172
The Australian Institute of Marine Science (AIMS) conducted a pilot study around the Harriet A oil production platform on the Northwest Shelf of Australia. We evaluated hepatic ethoxyresorufin-O-deethylase (EROD) activity, fluorescent aromatic compounds (FACs) in bile and immunodetection of CYP1A-like proteins in two Australian tropical fish species, Gold-Spotted Trevally (Carangoides fulvoguttatus) and Bar-Cheeked Coral Trout (Plectropomus maculatus) to assess exposure to petroleum hydrocarbons associated with produced formation water (PFW). Additionally, the incidence of hydrocarbon-degrading bacteria isolated from the liver and bile of all fish captured was examined. Low EROD activity was found in both species, with EROD activity in C. fulvoguttatus showing significant site differences. FACs and CYP1A protein levels in C. fulvoguttatus showed a clear trend in hydrocarbon exposure consistent with hydrocarbon chemistry data: Harriet A>Harriet C>reference site. P. maculatus showed elevated levels of FACs at Harriet A as compared to the reference site and demonstrated detectable levels of CYP1A-like proteins at these two sites. Hydrocarbon-degrading bacteria were found in the liver and bile of both species, yet there was no correlation by sites. Our results demonstrate that C. fulvoguttatus and P. maculatus have potential as indicator species for assessing the effects from exposure to petroleum hydrocarbons. Both FACs and CYP1A are providing warning signs that there is potential for biological effects on fish populations exposed to PFW around the Harriet A production platform. 相似文献