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11.
Impulse-response-function (IRF) models are designed for applications requiring a large number of climate change simulations,
such as multi-scenario climate impact studies or cost-benefit integrated-assessment studies. The models apply linear response
theory to reproduce the characteristics of the climate response to external forcing computed with sophisticated state-of-the-art
climate models like general circulation models of the physical ocean-atmosphere system and three-dimensional oceanic-plus-terrestrial
carbon cycle models. Although highly computer efficient, IRF models are nonetheless capable of reproducing the full set of
climate-change information generated by the complex models against which they are calibrated. While limited in principle to
the linear response regime (less than about 3 ∘C global-mean temperature change), the applicability of the IRF model presented has been extended into the nonlinear domain
through explicit treatment of the climate system's dominant nonlinearities: CO2 chemistry in ocean water, CO2 fertilization of land biota, and sublinear radiative forcing. The resultant nonlinear impulse-response model of the coupled
carbon cycle-climate system (NICCS) computes the temporal evolution of spatial patterns of climate change for four climate
variables of particular relevance for climate impact studies: near-surface temperature, cloud cover, precipitation, and sea
level. The space-time response characteristics of the model are derived from an EOF analysis of a transient 850-year greenhouse
warming simulation with the Hamburg atmosphere-ocean general circulation model ECHAM3-LSG and a similar response experiment
with the Hamburg carbon cycle model HAMOCC. The model is applied to two long-term CO2 emission scenarios, demonstrating that the use of all currently estimated fossil fuel resources would carry the Earth's climate
far beyond the range of climate change for which reliable quantitative predictions are possible today, and that even a freezing
of emissions to present-day levels would cause a major global warming in the long term.
Received: 28 January 2000 / Accepted: 9 March 2001 相似文献
12.
A new method for stratospheric trace gas analysis based upon in situ ion composition measurements is presented. The strength of the method lies in its extremely high sensitivity which at present allows for detection limits of the order of 100–1000 molecules cm?3 corresponding to volume mixing ratios of the order of 10?15–10?14 around 35 km altitude. The typical uncertainty of derived trace gas abundances is plus or minus a factor of about two. A disadvantage lies in the selectivity of the method which is restricted to trace gases having either large proton affinities, dipole moments or gas phase acidities. Analyses of water vapor and nitric acid vapor in the upper stratosphere are presented. 相似文献
13.
L. A. De Bock P. E. Joos K. J. Noone R. A. Pockalny R. E. Van Grieken 《Journal of Atmospheric Chemistry》2000,37(3):299-329
The chemical composition of individual particles >0.2 m sampled duringthe MAST-experiment wereanalysed by SEM-EDX, in combination with multivariatetechniques. The objective of this experiment was toidentify the mechanisms responsible for themodification of marine stratocumulus clouds byemissions from ships and in a wider sense to provideinformation on the global processes involved inatmospheric modification of cloud albedo. Aerosolswere examined under different MBL pollution levels(clean, intermediately polluted and moderatelypolluted) in five different reservoirs: backgroundbelow-cloud and above-cloud aerosol; background clouddroplet residual particles; below-cloud ship plumeaerosol and ship track cloud droplet residualparticles.In this study a relation was provided between theaerosol emitted from the ship's stack to an effect incloud. Additionally, a large fraction of the ambientaerosol was found to be composed of organic materialor other compounds, consisting of low Z-elements,associated with chlorine. Their number fraction waslargest in clean marine boundary layers, and decreasedwith increasing pollution levels. The fraction of`transformed sea salt' (Na, Cl, S), on the other hand,increased with the pollution level in the MBL. Only20% of the particles fell within the detectable rangeof the analysis. 相似文献
14.
15.
It is commonly suggested that older non-Western migrants have a higher risk of experiencing multiple forms of disadvantage than native older adults. However, few researchers have studied the life situation and urban conditions of older migrants in relation to each other and in comparison to native older adults with a similar socioeconomic status. This paper investigates whether different groups of older non-Western migrants (of Surinamese, Moroccan and Turkish origin) in deprived neighbourhoods in Amsterdam experience similar or different levels of multiple disadvantage compared to socioeconomically similar native Dutch older residents living in the same neighbourhoods, and explores how multiple disadvantage can be explained in relation to life and residential histories and neighbourhood changes. Analysis of 85 in-depth interviews indicates that all categories of low-income older adults experienced certain levels of disadvantage, although they evaluated their circumstances using different frames of reference. Regarding health, both native-born and migrant older people experienced chronic illness. However, the results of this study suggest that those in the latter group (especially Moroccans and Turks) experienced health problems and related functional limitations at a younger age. Native Dutch older adults were somewhat better off with respect to the availability of household resources, but compared to older non-Western migrants were more likely to experience the negative effects of neighbourhood deprivation. In summary, this study refines common assertions that older migrants are more disadvantaged than native older adults. Differences in experiences of advantage and disadvantage have their origin in differences in life and residential histories and neighbourhood change. 相似文献
16.
Urban poverty in Western countries is usually defined in terms of social exclusion and integration. Welfare states can be
characterized according to three modes of integration, namely market exchange, redistribution and reciprocity. This paper
compares the mechanisms of the social integration of unemployed single mothers with those of unemployed men. In two deprived
neighbourhoods in Amsterdam, unemployed single mothers and unemployed native-born men were interviewed about their coping
strategies with respect to the labour market, social security institutions and social networks. Although the single mothers
have serious financial problems, they are better integrated into society at large than the unemployed men are. The single
mothers are strongly oriented towards the labour market, successful in getting support from the social security institutions,
have strong and supportive social networks, and are integrated into their neighbourhoods. In the conclusion we challenge the
idea of vulnerable single mothers and demonstrate the relatively successful integration of this category of women.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Modelling the concentration of atmospheric CO2 during the Younger Dryas climate event 总被引：1，自引：0，他引：1
O. Marchal T. F. Stocker F. Joos A. Indermühle T. Blunier J. Tschumi 《Climate Dynamics》1999,15(5):341-354
The Younger Dryas (YD, dated between 12.7–11.6 ky BP in the GRIP ice core, Central Greenland) is a distinct cold period in
the North Atlantic region during the last deglaciation. A popular, but controversial hypothesis to explain the cooling is
a reduction of the Atlantic thermohaline circulation (THC) and associated northward heat flux as triggered by glacial meltwater.
Recently, a CH4-based synchronization of GRIP δ18O and Byrd CO2 records (West Antarctica) indicated that the concentration of atmospheric CO2 (COatm
2) rose steadily during the YD, suggesting a minor influence of the THC on COatm
2 at that time. Here we show that the COatm
2 change in a zonally averaged, circulation-biogeochemistry ocean model when THC is collapsed by freshwater flux anomaly is
consistent with the Byrd record. Cooling in the North Atlantic has a small effect on COatm
2 in this model, because it is spatially limited and compensated by far-field changes such as a warming in the Southern Ocean.
The modelled Southern Ocean warming is in agreement with the anti-phase evolution of isotopic temperature records from GRIP
(Northern Hemisphere) and from Byrd and Vostok (East Antarctica) during the YD. δ13C depletion and PO4 enrichment are predicted at depth in the North Atlantic, but not in the Southern Ocean. This could explain a part of the
controversy about the intensity of the THC during the YD. Potential weaknesses in our interpretation of the Byrd CO2 record in terms of THC changes are discussed.
Received: 27 May 1998 / Accepted: 5 November 1998 相似文献
18.
Johannes Rempfer Thomas F. Stocker Fortunat Joos Jean-Claude Dutay 《Geochimica et cosmochimica acta》2011,75(20):5927-5950
The neodymium (Nd) isotopic composition (?Nd) of seawater is a quasi-conservative tracer of water mass mixing and is assumed to hold great potential for paleoceanographic studies. Here we present a comprehensive approach for the simulation of the two neodymium isotopes 143Nd, and 144Nd using the Bern3D model, a low resolution ocean model. The high computational efficiency of the Bern3D model in conjunction with our comprehensive approach allows us to systematically and extensively explore the sensitivity of Nd concentrations and ?Nd to the parametrisation of sources and sinks. Previous studies have been restricted in doing so either by the chosen approach or by computational costs. Our study thus presents the most comprehensive survey of the marine Nd cycle to date.Our model simulates both Nd concentrations as well as ?Nd in good agreement with observations. ?Nd covaries with salinity, thus underlining its potential as a water mass proxy. Results confirm that the continental margins are required as a Nd source to simulate Nd concentrations and ?Nd consistent with observations. We estimate this source to be slightly smaller than reported in previous studies and find that above a certain magnitude its magnitude affects ?Nd only to a small extent. On the other hand, the parametrisation of the reversible scavenging considerably affects the ability of the model to simulate both, Nd concentrations and ?Nd. Furthermore, despite their small contribution, we find dust and rivers to be important components of the Nd cycle. In additional experiments, we systematically varied the diapycnal diffusivity as well as the Atlantic-to-Pacific freshwater flux to explore the sensitivity of Nd concentrations and its isotopic signature to the strength and geometry of the overturning circulation. These experiments reveal that Nd concentrations and ?Nd are comparatively little affected by variations in diapycnal diffusivity and the Atlantic-to-Pacific freshwater flux. In contrast, an adequate representation of Nd sources and sinks is crucial to simulate Nd concentrations and ?Nd consistent with observations. The good agreement of our results with observations paves the way for the evaluation of the paleoceanographic potential of ?Nd in further model studies. 相似文献
19.
Joos Cadisch 《International Journal of Earth Sciences》1928,19(2):105-119
Ohne Zusammenfassung 相似文献
20.