排序方式： 共有19条查询结果，搜索用时 984 毫秒
1.
Weather in the North Gulf of Alaska is characterized by a high frequency of deep synoptic-scale low-pressure systems, especially during the cold season. The strong pressure gradients of these storms interact with the extremely rugged terrain of the coastal mountains to produce a variety of channeled flows. These surface wind regimes are not well documented in the scientific community, due to the paucity of observations. Modeling of these phenomena in regions of complex terrain is of great interest to those working with hydrodynamic, wave, and pollutant transport models in coastal and shelf areas. Such models, when coupled with ocean and coastal-ecology counterparts, give a broad view of the role surface winds play in shaping local coastal marine ecosystem in this region. This paper presents a climatology of simulated low-level wind jets over the domain of Cook Inlet and Shelikof Strait along Alaska's south-central coast. Daily simulations using the RAMS model were conducted in a 36-h forecast mode for the cold-season period 10/1/03 to 3/31/04. Systematic analysis of the resulting simulated low-level wind field makes it possible to characterize these jets and gap flows in spatial and temporal detail. The comparison between the RAMS winds and the Synthetic Aperture Radar (SAR)-derived winds when available verifies the existence of these wind jets and the capability of the model to simulate these cases. Clearly, the results of a study in this region depend on the fidelity of the model at these scales (O[5 km]). The SAR comparisons attempt to help establish this. From the 6 months of simulations over Cook Inlet and Shelikof Strait, the low-level wind jets are classified into 10 different regimes by location and orientation. These regimes are categorized into four more general groups: cross-channel westerly, easterly, and up and down Inlet flows. The nature of a particular regime is largely a function of pressure gradient orientation and local topography. Jets in the same group have a similar occurrence distribution with time. Some form of jet occurred in the study region almost daily each month of the period, with December 2003 having the highest frequency of wind jets. 相似文献
2.
D. Perner U. Platt M. Trainer G. Hübler J. Drummond W. Junkermann J. Rudolph B. Schubert A. Volz D. H. Ehhalt K. J. Rumpel G. Helas 《Journal of Atmospheric Chemistry》1987,5(2):185-216
Using long path UV absorption spectroscopy we have measured OH concentrations close to the earth's surface. The OH values observed at two locations in Germany during 1980 through 1983 range from 0.7×106 to 3.2×106 cm-3. Simultaneously we measured the concentrations of O3, H2O, NO, NO2, CH4, CO, and the light non methane hydrocarbons. We also determined the photolysis rates of O3 and NO2. This allows calculations of OH using a zero dimensional time depdendent model. The modelled OH concentrations significantly exceed the measured values for low NO
x
concentrations. It is argued that additional, so far unidentified. HO
x
loss reactions must be responsible for that discrepancy. 相似文献
3.
Hinton DE Kullman SW Hardman RC Volz DC Chen PJ Carney M Bencic DC 《Marine pollution bulletin》2005,51(8-12):635-648
In this age of modern biology, aquatic toxicological research has pursued mechanisms of action of toxicants. This has provided potential tools for ecotoxicologic investigations. However, problems of biocomplexity and issues at higher levels of biological organization remain a challenge. In the 1980s and 1990s and continuing to a lesser extent today, organisms residing in highly contaminated field sites or exposed in the laboratory to calibrated concentrations of individual compounds were carefully analyzed for their responses to priority pollutants. Correlation of biochemical and structural analyses in cultured cells and tissues, as well as the in vivo exposures led to the production and application of biomarkers of exposure and effect and to our awareness of genotoxicity and its chronic manifestations, such as neoplasms, in wild fishes. To gain acceptance of these findings in the greater environmental toxicology community, “validation of the model” versus other, better-established often rodent models, was necessary and became a major focus. Resultant biomarkers were applied to heavily contaminated and reference field sites as part of effects assessment and with investigations following large-scale disasters such as oil spills or industrial accidents.
Over the past 15 years, in the laboratory, small aquarium fish models such as medaka (Oryzias latipes), zebrafish (Danio rerio), platyfish (Xiphophorus species), fathead minnow (Pimephales promelas), and sheepshead minnow (Cyprinodon variegatus) were increasingly used establishing mechanisms of toxicants. Today, the same organisms provide reliable information at higher levels of biological organization relevant to ecotoxicology. We review studies resolving mechanisms of toxicity and discuss ways to address biocomplexity, mixtures of contaminants, and the need to relate individual level responses to populations and communities. 相似文献
4.
Tilo Usbeck Peter Waldner Matthias Dobbertin Christian Ginzler Christian Hoffmann Flurin Sutter Charlotte Steinmeier Richard Volz Gustav Schneiter Martine Rebetez 《Theoretical and Applied Climatology》2012,108(3-4):451-462
This study compares the surface wind speed and forest damage data of two exceptionally severe winter storms, Vivian 1990 and Lothar 1999. The study area comprises the region that suffered damage in Switzerland. The wind speed data were derived from simulations of MeteoSwiss (Federal Office of Meteorology and Climatology), measurements during the storm periods and expert analyses of the data. The remotely sensed forest damage data were provided by the Federal Office for the Environment and the forest cover data by Swiss Federal Statistical Office. We compared data on the peak gust and maximum average wind speed, with data on the spatially related forest area and forest damage area, and found some clear differences in the correlations between the different wind data and forest damage. Our results point generally to the damage-causing role of near-surface gusts at maximum wind speeds during the storm. These tended to be spatially distributed on a fine scale. In only a few cases were the results statistically significant. However, these results could probably be improved with better wind data. For example, gust measurements spatially closer to forests or simulations of gusts at maximum wind speed could be produced with a spatially higher resolution. 相似文献
5.
Differential developmental toxicity of naphthoic acid isomers in medaka (Oryzias latipes) embryos 总被引：1，自引：0，他引：1
Michael W. Carney Kyle Erwin Ron Hardman Bonny Yuen David C. Volz David E. Hinton Seth W. Kullman 《Marine pollution bulletin》2008,57(6-12):255
Polycyclic aromatic hydrocarbons (PAHs) are widespread persistent pollutants that readily undergo biotic and abiotic conversion to numerous transformation products in rivers, lakes and estuarine sediments. Here we characterize the developmental toxicity of four PAH transformation products each structural isomers of hydroxynaphthoic acid: 1H2NA, 2H1NA, 2H3NA, and 6H2NA. Medaka fish (Oryzias latipes) embryos and eleutheroembryos were used to determine toxicity. A 96-well micro-plate format was used to establish a robust, statistically significant platform for assessment of early life stages. Individual naphthoic acid isomers demonstrated a rank order of toxicity with 1H2NA > 2H1NA > 2H3NA > 6H2NA being more toxic. Abnormalities of circulatory system were most pronounced including pericardial edema and tube heart. To determine if HNA isomers were AhR ligands, spatial-temporal expression and activity of CYP1A was measured via in vivo EROD assessments. qPCR measurement of CYP1A induction proved different between isomers dosed at respective concentrations affecting 50% of exposed individuals (EC50s). In vitro, all ANH isomers transactivated mouse AhR using a medaka CYP1A promoter specific reporter assay. Circulatory abnormalities followed P450 induction and response was consistent with PAH toxicity. A 96-well micro-plates proved suitable as exposure chambers and provided statistically sound evaluations as well as efficient toxicity screens. Our results demonstrate the use of medaka embryos for toxicity analysis thereby achieving REACH objectives for the reduction of adult animal testing in toxicity evaluations. 相似文献
6.
F. Volz 《Theoretical and Applied Climatology》1964,13(2):249-260
Zusammefassung Um Trübungsbestimmungen nach Aktinometermessungen gegenüber demSchüeppschen Verfahren (und ähnlichen) wesentlich zu erleichtern, wird an Hand derSchüeppschen Unterlagen ein Diagramm zur Bestimmung des dekadischen TrübungskoeffizientenB
500 aus Messungen der Kurzstrahlung (J
K
, <625 nm) berechnet. Die so erhaltenen Werte vonJ
K
sind praktisch unabhängig vom -Exponenten der Dunstextinktion.J
K
-Werte fürB=0 verschiedener Autoren werden verglichen, und Trübungsgrößen verschiedener Diagramme (,T
K
,B nachSchüepp) werden in Beziehung gesetzt. Es wird darauf hingewiesen, daß dieSchüepp-sche Methode bei kleinen Trübungen wahrscheinlich etwas zu hohe Werte ergibt.
Mit 2 Textabbildungen 相似文献
Summary To simplify the determination of atmospheric turbidity by actinometric measurements with respect to theSchüepp method, a diagram has been computed from the data ofSchüepp to derive the decadic turbidity coefficientB 500 from measurements of short wave radiation (J K , <625 nm). Values ofJ K are practically independent of the -exponent of haze attenuation.J K -values forB=0 of different authors and turbidity values of different diagrams (,T K ,B Schüepp) are compared. It is pointed out that theSchüepp method yields probably slightly too high values with small turbidity.
Résumé Le calcul du trouble atmosphérique d'après les mesures actinométriques est assez compliqué selon la méthode deSchüepp ou d'autres méthodes semblables. Afin d'en faciliter notablement la détermination, l'auteur a calculé une abaque en se basant sur les données deSchüepp. Ce diagramme permet d'évaluer le coefficient de trouble atmosphérique décadaireB 500 en partant de la mesure du rayonnement à ondes courtes (J K , <625 m). Les valeurs deJ K obtenues alors sont pratiquement indépendantes de l'exposant de l'extinction due à la brume. Les valeurs deJ K pourB=0 et provenant de divers auteurs sont comparées entre elles. On a en outre établi le rapport existant entre le trouble atmosphérique calculé d'après divers diagrammes (,T K ,B Schüepp). On rend le lecteur attentif au fait que les valeurs calculées selonSchüepp sont probablement trop élevées lorsque le trouble atmosphérique est peu important.
Mit 2 Textabbildungen 相似文献
7.
A. Hahne A. Volz D. H. Ehhalt H. Cosatto W. Roether W. Weiss B. Kromer 《Pure and Applied Geophysics》1978,116(2-3):575-582
Depth profiles of the chlorofluoromethanes (CFM), CFCl3 and CF2Cl2, have been obtained together with tritium profiles from water samples collected in the Norwegian Sea between surface and 2800 m depth. CFM analysis was performed by vacuum extraction of the dissolved gases from 500 ml samples of seawater and subsequent gaschromatographic measurement. The CFM concentration decreases with depth to about 10 percent of surface concentration at depths below 2000 m. The same behaviour is found for the tritium content. From a correlation of the CFM and tritium concentration the upper limit of the preindustrial atmospheric CFM levels can be estimated to 5 percent of the present day concentrations. 相似文献
8.
Dr. F. Volz 《Pure and Applied Geophysics》1955,31(1):119-123
Summary The indices of the wavelength dependency of the haze extinction which were currently determined from measurements of solar radiation and visibility at Mainz, show pronounced seasonal variations. The summer values are in general definitely higher than in winter. There is no connection with the scatter light types of the sky-light or with the meteorological situation.
Zusammenfassung Die Wellenlängenexponenten der Dunstextinktion, die in Mainz laufend aus Messungen der Sonnenstrahlung und der Sicht bestimmt wurden, zeigen starke jahreszeitliche Variationen. Insbesonders sind die Werte im Sommer meist deutlich höher als im Winter. Ein Zusammenhang mit den Streulichttypen des Himmelslichts oder der meteorologischen Situation besteht nicht.
Sommaire L'exposant de la longueur d'onde de l'extinction brumeuse qui a été déterminé de façon continue des mesures de la radiation solaire et de la visibilité montre des fortes variations annuelles. Tout spécialement les valeurs sont d'été sensiblement plus élevées que celles en hiver. Une relation avec les types de lumière diffuse céleste et la situation météorologique n'existe pas.相似文献
9.
A detector for the chemiluminescent measurement of NO in background air is described. A large reduction of interferences is achieved by using a stabilized ozone generator which allows operation of the instrument at lower O3 concentrations. Purification and humidification of the O3 stream further reduces interferences and shortens the instrumental clean-up time, which is important for aircraft missions. From a series of laboratory tests and from measurements performed aboard an aircraft it is demonstrated that the remaining interferences are acceptable for measurements in the undisturbed troposphere. In particular, no remnant NO signal is observed in clean air at night. During flight, a detection limit (2) of 20 ppt is achieved for a 1 min integration time. 相似文献
10.
ROBERT O''BRIEN BIMAL K.SINHA WILLIAM P.SMITH Statistical Policy Branch Environmental Protection Agency M St. SW Washington DC U.S.A. 《地理学报(英文版)》1991,(3)
The object of this paper is to develop a suitable statistical procedure to evaluate clean-up standards athazardous waste sites.Under the assumptions that contaminant masses at a site follow a gammadistribution and that the data from the pre-remediation baseline sample as well as from the interim orfinal sample taken after a certain period of operation are both distributed as gamma with the same shapeparameter but different scale parameters,we derive a uniformly most powerful unbiased test of thehypothesis that a specified percentage of contaminant mass has been reduced.A large-sampleapproximation of the exact test procedure and a comparison with the likelihood ratio test are provided. 相似文献