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131.
Greene Brian R. Kral Stephan T. Chilson Phillip B. Reuder Joachim 《Boundary-Layer Meteorology》2022,183(3):321-353
Boundary-Layer Meteorology - We explore the potential of a new method for the estimation of profiles of turbulence statistics in the stable boundary layer (SBL). By applying gradient-based scaling... 相似文献
132.
Johannes Becherer Jacobus Hofstede Ulf Gräwe Kaveh Purkiani Elisabeth Schulz Hans Burchard 《Ocean Dynamics》2018,68(1):131-151
The impact of sea level rise (SLR) on the future morphological development of the Wadden Sea (North Sea) is investigated by means of extensive process-resolving numerical simulations. A new sediment and morphodynamic module was implemented in the well-established 3D circulation model GETM. A number of different validations are presented, ranging from an idealized 1D channel over a semi-idealized 2D Wadden Sea basin to a fully coupled realistic 40-year hindcast without morphological amplification of the Sylt-Rømøbight, a semi-enclosed subsystem of the Wadden Sea. Based on the results of the hindcast, four distinct future scenarios covering the period 2010–2100 are simulated. While these scenarios differ in the strength of SLR and wind forcing, they also account for an expected increase of tidal range over the coming century. The results of the future projections indicate a transition from a tidal-flat-dominated system toward a lagoon-like system, in which large fractions of the Sylt-Rømøbight will remain permanently covered by water. This has potentially dramatic implications for the unique ecosystem of the Wadden Sea. Although the simulations also predict an increased accumulation of sediment in the back-barrier basin, this accumulation is far too weak to compensate for the rise in mean sea level. 相似文献
133.
Uwe Mikolajewicz Matthias Gröger Ernst Maier-Reimer Guy Schurgers Miren Vizcaíno Arne M. E. Winguth 《Climate Dynamics》2007,28(6):599-633
A new complex earth system model consisting of an atmospheric general circulation model, an ocean general circulation model,
a three-dimensional ice sheet model, a marine biogeochemistry model, and a dynamic vegetation model was used to study the
long-term response to anthropogenic carbon emissions. The prescribed emissions follow estimates of past emissions for the
period 1751–2000 and standard IPCC emission scenarios up to the year 2100. After 2100, an exponential decrease of the emissions
was assumed. For each of the scenarios, a small ensemble of simulations was carried out. The North Atlantic overturning collapsed
in the high emission scenario (A2) simulations. In the low emission scenario (B1), only a temporary weakening of the deep
water formation in the North Atlantic is predicted. The moderate emission scenario (A1B) brings the system close to its bifurcation
point, with three out of five runs leading to a collapsed North Atlantic overturning circulation. The atmospheric moisture
transport predominantly contributes to the collapse of the deep water formation. In the simulations with collapsed deep water
formation in the North Atlantic a substantial cooling over parts of the North Atlantic is simulated. Anthropogenic climate
change substantially reduces the ability of land and ocean to sequester anthropogenic carbon. The simulated effect of a collapse
of the deep water formation in the North Atlantic on the atmospheric CO2 concentration turned out to be relatively small. The volume of the Greenland ice sheet is reduced, but its contribution to
global mean sea level is almost counterbalanced by the growth of the Antarctic ice sheet due to enhanced snowfall. The modifications
of the high latitude freshwater input due to the simulated changes in mass balance of the ice sheet are one order of magnitude
smaller than the changes due to atmospheric moisture transport. After the year 3000, the global mean surface temperature is
predicted to be almost constant due to the compensating effects of decreasing atmospheric CO2 concentrations due to oceanic uptake and delayed response to increasing atmospheric CO2 concentrations before. 相似文献
134.
135.
Joachim W. Dippner 《Ocean Dynamics》1993,45(4):279-280
136.
Analysis of a dust sample (e.g. collected during a cometary rendezvous mission) by SIMS (Secondary Ion Mass Spectroscopy) can provide information on elemental abundances (? 100 amu), the molecular composition of grain surfaces, and isotopic ratios of selected elements. This can be accomplished with dust covering as little as 10?4 of the collector surface area. In order to demonstrate these capabilities a special experimental set-up for substrate preparation, dust collection and SIMS analysis of dust under ultrahigh vacuum conditions was developed. The comparison of elemental abundance ratios for different olivines and pyroxenes measured with the special SIMS equipment with that measured by an electron microprobe indicated an accuracy for SIMS of the elemental abundance measurements of ? 30%. By varying the energy threshold of secondary ions to be mass-analysed from 0 to 50 eV it is possible to identify molecular ions in the spectra and to estimate their abundance with respect to elemental ions on the same mass line. The ratios of molecular to elemental ions vary by a factor of 1–25. The concept for a future cometary rendezvous experiment as well as first results of chemical investigation on mineral dust samples obtained are reported. 相似文献
137.
Ø. Grøn 《Astrophysics and Space Science》1988,140(2):429-430
The gravitational field equations in Dunn's scalar-tensor theory of gravitation are generalized by including a cosmological constant. The resulting equations are solved for a Robertson-Walker line-element with flat three-space. The solution represents a cosmological model that develops into an inflationary era. 相似文献
138.
The classical region of the Holsteinian interglacial is in the vicinity of Hamburg and the Lower Elbe. It is defined on the basis of pollen and is clearly distinguishable from the Eemian interglacial (Hallik, 1960; Müller, 1974). The Holsteinian interglacial is represented by a sequence of sediments up to 100 m in thickness. These consist of limnic, fluvial, and marine beds and show a transgression up to the height of present sea-level.Twenty-seven molluscs from Holsteinian deposits were used for ESR dating. The ages show that the Holsteinian may be correlated with stage 7 of the deep sea record V28-238 (Shackleton and Opdyke, 1973). 相似文献
139.
140.
Various explanations of the bipolar-flow phenomenon in star-forming regions are compared and confronted with the observed facts. It is concluded that stellar-wind interpretations are inconsistent with the constraints. The exotic property of young stellar objects may be their extreme spin which implies strong magnetic fields and vacuum discharges above thee
± pair-formation threshold (of 1012 eV). Pair-plasma jets are thought to be centrifugally driven by young stars during their first 104±1 years of rapid rotation. 相似文献