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1.
Bayesian multi-model projection of climate: bias assumptions and interannual variability 总被引：1，自引：0，他引：1
Current climate change projections are based on comprehensive multi-model ensembles of global and regional climate simulations.
Application of this information to impact studies requires a combined probabilistic estimate taking into account the different
models and their performance under current climatic conditions. Here we present a Bayesian statistical model for the distribution
of seasonal mean surface temperatures for control and scenario periods. The model combines observational data for the control
period with the output of regional climate models (RCMs) driven by different global climate models (GCMs). The proposed Bayesian
methodology addresses seasonal mean temperatures and considers both changes in mean temperature and interannual variability.
In addition, unlike previous studies, our methodology explicitly considers model biases that are allowed to be time-dependent
(i.e. change between control and scenario period). More specifically, the model considers additive and multiplicative model
biases for each RCM and introduces two plausible assumptions (“constant bias” and “constant relationship”) about extrapolating
the biases from the control to the scenario period. The resulting identifiability problem is resolved by using informative
priors for the bias changes. A sensitivity analysis illustrates the role of the informative prior. As an example, we present
results for Alpine winter and summer temperatures for control (1961–1990) and scenario periods (2071–2100) under the SRES
A2 greenhouse gas scenario. For winter, both bias assumptions yield a comparable mean warming of 3.5–3.6°C. For summer, the
two different assumptions have a strong influence on the probabilistic prediction of mean warming, which amounts to 5.4°C
and 3.4°C for the “constant bias” and “constant relation” assumptions, respectively. Analysis shows that the underlying reason
for this large uncertainty is due to the overestimation of summer interannual variability in all models considered. Our results
show the necessity to consider potential bias changes when projecting climate under an emission scenario. Further work is
needed to determine how bias information can be exploited for this task. 相似文献
2.
The coupling of optimal economic growth and climate dynamics 总被引：1，自引：0，他引：1
Olivier Bahn Laurent Drouet Neil R. Edwards Alain Haurie Reto Knutti Socrates Kypreos Thomas F. Stocker Jean-Philippe Vial 《Climatic change》2006,79(1-2):103-119
In this paper, we study optimal economic growth programs coupled with climate change dynamics. The study is based on models derived from MERGE, a well established integrated assessment model (IAM). We discuss first the introduction in MERGE of a set of “tolerable window” constraints which limit both the temperature change and the rate of temperature change. These constraints, obtained from ensemble simulations performed with the Bern 2.5-D climate model, allow us to identity a domain intended to preserve the Atlantic thermohaline circulation. Next, we report on experiments where a two-way coupling is realized between the economic module of MERGE and an intermediate complexity “3-D-” climate model (C-GOLDSTEIN) which computes the changes in climate and mean temperature. The coupling is achieved through the implementation of an advanced “oracle based optimization technique” which permits the integration of information coming from the climate model during the search for the optimal economic growth path. Both cost-effectiveness and cost-benefit analysis modes are explored with this combined “meta-model” which we refer to as GOLDMERGE. Some perspectives on future implementations of these approaches in the context of “collaborative” or “community” integrated assessment modules are derived from the comparison of the different approaches. 相似文献
3.
Unlike many other environmental problems, the terms used to describe the phenomenon of increasing atmospheric concentrations
of anthropogenic greenhouse gases are many, with multiple and sometimes conflicting meanings. Whether there are meaningful
distinctions in public perceptions of “global warming,” “climate change,” and “global climate change” has been a topic of
research over the past decade. This study examines public preferences for these terms based on respondent characteristics,
including climate change beliefs, political affiliation, and audience segment status derived from the “Global Warming’s Six
Americas” classification. Certainty of belief in global warming, political affiliation and audience segment status were found
to be the strongest predictors of preference, although “I have no preference” was the modal response. Global warming appears
to be a more polarizing term than climate change, preferred most by people already concerned about the issue, and least by
people who don’t believe climate change is occurring. Further research is needed to identify which of these two names promotes
the engagement of people across the spectrum of climate change beliefs in constructive dialogue about the issue. 相似文献
4.
Maciej Sadowski 《Climatic change》2008,90(4):443-451
Adopted by COP 10 (Dec 1/CP.10) and approved by the MOP1, the Buenos Aires programme of adaptation and response measures opens
doors to intensify preparations for expected climate change. By this decision the COP, requested the SBSTA to develop a structured
5-year programme of work of the SBSTA on the scientific, technical and socio-economic aspects of impacts of, and vulnerability
and adaptation to, climate change. Consequently, the COP, by its decision 2/CP.11, adopted the “Five-year programme of work
of the Subsidiary Body for Scientific and Technological Advice on impacts, vulnerability and adaptation to climate change”
Finally during COP12 this programme was approved as “Nairobi Work Programme on impacts, vulnerability and adaptation to climate
change”. This programme has fundamental significance not only for developing countries, but also for industrialized nations
in which some sectors of the or social life are particularly vulnerable to climate change, specifically, inter alia EIT countries and new EU Member States. Further development of this adaptation programme economy should contain steps that
provide optimum economic and social effectiveness, risk management, identification of vulnerable sectors and gaps in knowledge,
preparation of a list of policy options, including an analysis of cost effectiveness, selection of the most effective policies,
and a preparedness implementation plan. In Poland the preliminary adaptation programme covered agriculture, water management,
and coastal zone management. For the time being, gaps in knowledge and preparedness measures have been identified. An estimation
of possible impact on these areas was based on chosen GCMs, and sea level rise IPCC scenarios. In conclusion, it was stated
that the results achieved should be seen as a first step forward and a more comprehensive study is necessary to update the
results and cover other sectors of the economy, such as health protection, spatial planning, ecosystems and forestry, and
to develop specific guidelines and recommendations for policy-makers. 相似文献
5.
K. Hasselmann 《Climate Dynamics》1997,13(9):601-611
The multi-variate optimal fingerprint method for the detection of an externally forced climate change signal in the presence
of natural internal variability is extended to the attribution problem. To determine whether a climate change signal which
has been detected in observed climate data can be attributed to a particular climate forcing mechanism, or combination of
mechanisms, the predicted space–time dependent climate change signal patterns for the candidate climate forcings must be specified.
In addition to the signal patterns, the method requires input information on the space–time dependent covariance matrices
of the natural climate variability and of the errors of the predicted signal patterns. The detection and attribution problem
is treated as a sequence of individual consistency tests applied to all candidate forcing mechanisms, as well as to the null
hypothesis that no climate change has taken place, within the phase space spanned by the predicted climate change patterns.
As output the method yields a significance level for the detection of a climate change signal in the observed data and individual
confidence levels for the consistency of the retrieved climate change signal with each of the forcing mechanisms. A statistically
significant climate change signal is regarded as consistent with a given forcing mechanism if the statistical confidence level
exceeds a given critical value, but is attributed to that forcing only if all other candidate climate change mechanisms (from
a finite set of proposed mechanisms) are rejected at that confidence level. Although all relations can be readily expressed
in standard matrix notation, the analysis is carried out using tensor notation, with a metric given by the natural-variability
covariance matrix. This simplifies the derivations and clarifies the invariant relation between the covariant signal patterns
and their contravariant fingerprint counterparts. The signal patterns define the reduced vector space in which the climate
trajectories are analyzed, while the fingerprints are needed to project the climate trajectories onto this reduced space.
Received: 19 April 1996/Accepted: 21 April 1997 相似文献
6.
The modification of greenhouse gas warming by the direct effect of sulphate aerosols 总被引：1，自引：0，他引：1
The Canadian Centre for Climate Modelling and Analysis (CCCma) second generation climate model (GCMII) consists of an atmospheric
GCM coupled to mixed layer ocean. It is used to investigate the climate response to a doubling of the CO2 concentration together with the direct effect of scattering by sulphate aerosols. As expected, the aerosols offset some of
the greenhouse gas (GHG) warming; the global annual mean screen temperature change due to doubled CO2 is 3.4 °C in this model and this is reduced to 2.7 °C when an estimate of the direct effect of anthropogenic sulphate aerosols
is included. The pattern of climate response to the comparatively localized aerosol forcing is not itself localized, and it
bears a striking resemblance to the response pattern that arises from the globally distributed change in GHG forcing. This
“non-local” response to “localized” forcing indicates that the pattern of climate response is determined, to first order,
by the overall magnitude of the change in forcing rather than its detailed nature or structure. Feedback processes operating
in the system apparently determine this pattern by locally amplifying and suppressing the response to the magnitude of the
change in forcing. The influence of the location of the change in forcing is relatively small. These “non-local” and “local”
effects of aerosol forcing are characterized and displayed and some of their consequences discussed. Effects on the moisture
budget and on the energetics of the global climate are also examined.
Received: 10 June 1997 / Accepted: 8 January 1998 相似文献
7.
Weather services base their operational definitions of “present” climate on past observations, using a 30-year normal period
such as 1961–1990 or 1971–2000. In a world with ongoing global warming, however, past data give a biased estimate of the actual
present-day climate. Here we propose to correct this bias with a “delta change” method, in which model-simulated climate changes
and observed global mean temperature changes are used to extrapolate past observations forward in time, to make them representative
of present or future climate conditions. In a hindcast test for the years 1991–2002, the method works well for temperature,
with a clear improvement in verification statistics compared to the case in which the hindcast is formed directly from the
observations for 1961–1990. However, no improvement is found for precipitation, for which the signal-to-noise ratio between
expected anthropogenic changes and interannual variability is much lower than for temperature. An application of the method
to the present (around the year 2007) climate suggests that, as a geographical average over land areas excluding Antarctica,
8–9 months per year and 8–9 years per decade can be expected to be warmer than the median for 1971–2000. Along with the overall
warming, a substantial increase in the frequency of warm extremes at the expense of cold extremes of monthly-to-annual temperature
is expected. 相似文献
8.
Introduction to the TAC special issue: The RegCNET network 总被引：2，自引：0，他引：2
F. Giorgi J. S. Pal X. Bi L. Sloan N. Elguindi F. Solmon 《Theoretical and Applied Climatology》2006,86(1-4):1-4
Summary Fostering climate research in economically developing nations (EDNs) is especially important because the welfare and economies
of these nations are particularly dependent on climate and its variability. A critical factor that undermines the advancement
of research in EDNs is that many EDN scientists are confronted with scientific isolation and lack of exposure to state-of-the-art
research methodologies. One of the means to ameliorate this problem is to build “south–south” (i.e. EDN–EDN) and “north–south”
(i.e. EDN–EAN, or economically advanced nations) research partnerships, which become more effective when they are based on
collaborative projects where the participants share their respective expertise. This is the central paradigm underlying the
formation of the REGional Climate research NETwork, or RegCNET. 相似文献
9.
Severe climate-induced water shortage and extremes in Crete 总被引：1，自引：0，他引：1
Ioannis K. Tsanis Aristeidis G. Koutroulis Ioannis N. Daliakopoulos Daniela Jacob 《Climatic change》2011,106(4):667-677
Climate change is expected to have a significant impact on the hydrologic cycle, creating changes in freshwater resources.
The Intergovernmental Panel on Climate Change (IPCC) predicts that, as a result, floods and prolonged droughts will take place
at increasingly frequent periods. The Mediterranean has been described as one of the main climate change “hot-spots”, with
recent simulations showing a collective picture of substantial drying and warming. This effect appears more pronounced during
warm periods, when the seasonal decrease of precipitation can exceed control climatology by 25–30%. Despite the decreasing
annual rainfall trend, an increase in the amount and intensity of wintertime rainfall is evident. However, the scientific
question on the quantitative impact of these signals to small scale coastal watersheds and Mediterranean islands has not been
answered. The state-of-the-art Ensembles dataset was employed to assess the impact of the changing climate on the water availability
of the island of Crete at basin scale. Here, the Ensembles precipitation and temperature data is used as input for a rainfall–runoff
model previous calibrated for the whole island with the principle of regionalization. Data analysis for the period 1970–2100
reveals an overall decreasing precipitation trend which, combined with a temperature rise, leads to substantial reduction
of water availability. Quantitative results of hydrological change provide the data required to improve knowledge and adaptation
policy to water shortages. 相似文献
10.
The question of whether and to what extent global warming may be changing tropical cyclone (TC) activity is of great interest
to decision makers. The presence of a possible climate change signal in TC activity is difficult to detect because interannual
variability necessitates analysis over longer time periods than available data allow. Projections of future TC activity are
hindered by computational limitations and uncertainties about changes in regional climate, large scale patterns, and TC response.
This review discusses the state of the field in terms of theory, modeling studies and data. While Atlantic TCs have recently
become more intense, evidence for changes in other basins is not persuasive, and changes in the Atlantic cannot be clearly
attributed to either natural variability or climate change. However, whatever the actual role of climatic change, these concerns
have opened a “policy window” that, if used appropriately, could lead to improved protection against TCs. 相似文献
11.
The energy cycle characterizes basic aspects of the physical behaviour of the climate system. Terms in the energy cycle involve
first and second order climate statistics (means, variances, covariances) and the intercomparison of energetic quantities
offers physically motivated “second order” insight into model and system behaviour. The energy cycle components of 12 models
participating in AMIP2 are calculated, intercompared and assessed against results based on NCEP and ERA reanalyses. In general,
models simulate a modestly too vigorous energy cycle and the contributions to and reasons for this are investigated. The results
suggest that excessive generation of zonal available potential energy is an important driver of the overactive energy cycle
through “generation push” while excessive dissipation of eddy kinetic energy in models is implicated through “dissipation
pull‘’. The study shows that “ensemble model” results are best or among the best in the comparison of energy cycle quantities
with reanalysis-based values. Thus ensemble approaches are apparently “best” not only for the simulation of 1st order climate
statistics as in Lambert and Boer (Clim Dyn 17:83–106, 2001) but also for the higher order climate quantities entering the
energy cycle. 相似文献
12.
U. Cubasch B. D. Santer A. Hellbach G. Hegerl H. Höck E. Maier-Reimer U. Mikolajewicz A. Stössel R. Voss 《Climate Dynamics》1994,10(1-2):1-19
Four time-dependent greenhouse warming experiments were performed with the same global coupled atmosphere-ocean model, but with each simulation using initial conditions from different snapshots of the control run climate. The radiative forcing — the increase in equivalent CO2 concentrations from 1985–2035 specified in the Intergovernmental Panel on Climate Change (IPCC) scenario A — was identical in all four 50-year integrations. This approach to climate change experiments is called the Monte Carlo technique and is analogous to a similar experimental set-up used in the field of extended range weather forecasting. Despite the limitation of a very small sample size, this approach enables the estimation of both a mean response and the between-experiment variability, information which is not available from a single integration. The use of multiple realizations provides insights into the stability of the response, both spatially, seasonally and in terms of different climate variables. The results indicate that the time evolution of the global mean warming signal is strongly dependent on the initial state of the climate system. While the individual members of the ensemble show considerable variation in the pattern and amplitude of near-surface temperature change after 50 years, the ensemble mean climate change pattern closely resembles that obtained in a 100-year integration performed with the same model. In global mean terms, the climate change signals for near surface temperature, the hydrological cycle and sea level significantly exceed the variability among the members of the ensemble. Due to the high internal variability of the modelled climate system, the estimated detection time of the global mean temperature change signal is uncertain by at least one decade. While the ensemble mean surface temperature and sea level fields show regionally significant responses to greenhouse-gas forcing, it is not possible to identify a significant response in the precipitation and soil moisture fields, variables which are spatially noisy and characterized by large variability between the individual integrations. 相似文献
13.
W. M. Connolley 《Climate Dynamics》1997,13(10):745-756
Using a hierarchy of climate models together with observations from gridded analyses, I examine the atmosphere-only and coupled
ocean-atmosphere variability in the general circulation for the region south of 40 °S. The variability in mean sea level pressure
(MSLP) is well simulated by the coupled models. A complication is that the difference between the two analyses used for verification
is comparable to the analysis-model differences. An increase in variability is seen within the hierarchy of model runs although
even a model without interannual variations in sea surface temperatures (SSTs) captures most of the observed variability.
The temporal variation in MSLP in southern high latitudes has a white spectrum consistent with “random” forcing by weather
events and a decoupling from oceanic “integration”. In contrast, the spatial pattern of MSLP variability shows large-scale
structure that is consistent between observations and various models, even without interannual variation in SSTs. This shows
that the models are sufficiently skillful to reproduce the pattern of observed variability and suggests that the pattern of
variability is a characteristic of the land-sea distribution and topography.
Received: 18 December 1996/Accepted: 23 May 1997 相似文献
14.
Regional climate model sensitivity to domain size 总被引：3，自引：1，他引：2
Regional climate models are increasingly used to add small-scale features that are not present in their lateral boundary conditions
(LBC). It is well known that the limited area over which a model is integrated must be large enough to allow the full development
of small-scale features. On the other hand, integrations on very large domains have shown important departures from the driving
data, unless large scale nudging is applied. The issue of domain size is studied here by using the “perfect model” approach.
This method consists first of generating a high-resolution climatic simulation, nicknamed big brother (BB), over a large domain
of integration. The next step is to degrade this dataset with a low-pass filter emulating the usual coarse-resolution LBC.
The filtered nesting data (FBB) are hence used to drive a set of four simulations (LBs for Little Brothers), with the same
model, but on progressively smaller domain sizes. The LB statistics for a climate sample of four winter months are compared
with BB over a common region. The time average (stationary) and transient-eddy standard deviation patterns of the LB atmospheric
fields generally improve in terms of spatial correlation with the reference (BB) when domain gets smaller. The extraction
of the small-scale features by using a spectral filter allows detecting important underestimations of the transient-eddy variability
in the vicinity of the inflow boundary, which can penalize the use of small domains (less than 100 × 100 grid points). The
permanent “spatial spin-up” corresponds to the characteristic distance that the large-scale flow needs to travel before developing
small-scale features. The spin-up distance tends to grow in size at higher levels in the atmosphere. 相似文献
15.
Stewart Cohen Denise Neilsen Scott Smith Tina Neale Bill Taylor Mark Barton Wendy Merritt Younes Alila Philippa Shepherd Roger Mcneill James Tansey Jeff Carmichael Stacy Langsdale 《Climatic change》2006,75(3):331-358
The research activity described in this report is a comprehensive regional assessment of the impacts of climate change on
water resources and options for adaptation in the Okanagan Basin. The ultimate goal of the project is to develop integrated
climate change and water resource scenarios to stimulate a multistakeholder discussion on the implications of climate change
for water management in the region.
The paper describes two main objectives: (a) providing a set of research products that will be of relevance to regional interests
in the Okanagan, and (b) establishing a methodology for participatory integrated assessment of regional climate change impacts
and adaptation that could be applied to climate-related concerns in Canada and other countries.
This collaborative study has relied on field research, computer-based models, and dialogue exercises to generate an assessment
of future implications, and to learn about regional views on the prospects for adaptation. Along the way, it has benefited
from strong partnerships with governments, researchers, local water practitioners, and user groups. Building on the scenario-based
study components, and a series of interviews and surveys undertaken for the water management and adaptation case study components,
a set of stakeholder dialogue sessions were organized which focused on identifying preferred adaptation options and processes
for their implementation. Rather than seeking consensus on the “best” option or process, regional interests were asked to
consider a range of available options as part of an adaptation portfolio that could address both supply side and demand side
aspects of water resources management in the Okanagan.
The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright. 相似文献
16.
US public awareness of the reality and risks of human-caused climate change remains limited, despite strong evidence presented
in the IPCC and other major climate assessments. One contributing factor may be that the immense collective effort to produce
periodic climate assessments is typically not well matched with public communication and outreach efforts for these reports,
leaving a vacuum to be filled by less authoritative sources. Print and online media coverage provides one metric of the US
public reach of selected climate assessments between 2000 and 2010. The number of Lexis-Nexis articles for the search terms
“climate change” or “global warming” within 14 days of each report’s release varied significantly over time with a peak occurring in 2007. When compared to background
“chatter” relating to climate change, each assessment had widely diverse penetration in the US media (~4% for US National Climate
Assessment in 2000; ~17% for Arctic Climate Impacts Assessment in 2004; ~19% and ~10% for Intergovernmental Panel on Climate
Change (IPCC) Fourth Assessment Report Working Group I and Working Group II respectively in 2007; ~4% for the US Global Change
Research Program (USGCRP) assessment report in 2009; and ~5% for US National Research Council’s America’s Climate Choices
reports in 2010). We propose ways to improve the public reach of climate assessments, focusing in particular on approaches
to more effectively characterize and communicate the role of uncertainty in human actions as distinct from other sources of
uncertainty across the range of possible climate futures. 相似文献
17.
Empirical-statistical downscaling and error correction of regional climate models and its impact on the climate change signal 总被引：7，自引：3，他引：4
Realizing the error characteristics of regional climate models (RCMs) and the consequent limitations in their direct utilization
in climate change impact research, this study analyzes a quantile-based empirical-statistical error correction method (quantile
mapping, QM) for RCMs in the context of climate change. In particular the success of QM in mitigating systematic RCM errors,
its ability to generate “new extremes” (values outside the calibration range), and its impact on the climate change signal
(CCS) are investigated. In a cross-validation framework based on a RCM control simulation over Europe, QM reduces the bias
of daily mean, minimum, and maximum temperature, precipitation amount, and derived indices of extremes by about one order
of magnitude and strongly improves the shapes of the related frequency distributions. In addition, a simple extrapolation
of the error correction function enables QM to reproduce “new extremes” without deterioration and mostly with improvement
of the original RCM quality. QM only moderately modifies the CCS of the corrected parameters. The changes are related to trends
in the scenarios and magnitude-dependent error characteristics. Additionally, QM has a large impact on CCSs of non-linearly
derived indices of extremes, such as threshold indices. 相似文献
18.
Christoph C. Raible Carlo Casty Jürg Luterbacher Andreas Pauling Jan Esper David C. Frank Ulf Büntgen Andreas C. Roesch Peter Tschuck Martin Wild Pier-Luigi Vidale Christoph Schär Heinz Wanner 《Climatic change》2006,79(1-2):9-29
A detailed analysis is undertaken of the Atlantic-European climate using data from 500-year-long proxy-based climate reconstructions, a long climate simulation with perpetual 1990 forcing, as well as two global and one regional climate change scenarios. The observed and simulated interannual variability and teleconnectivity are compared and interpreted in order to improve the understanding of natural climate variability on interannual to decadal time scales for the late Holocene. The focus is set on the Atlantic-European and Alpine regions during the winter and summer seasons, using temperature, precipitation, and 500 hPa geopotential height fields. The climate reconstruction shows pronounced interdecadal variations that appear to “lock” the atmospheric circulation in quasi-steady long-term patterns over multi-decadal periods controlling at least part of the temperature and precipitation variability. Different circulation patterns are persistent over several decades for the period 1500 to 1900. The 500-year-long simulation with perpetual 1990 forcing shows some substantial differences, with a more unsteady teleconnectivity behaviour. Two global scenario simulations indicate a transition towards more stable teleconnectivity for the next 100 years. Time series of reconstructed and simulated temperature and precipitation over the Alpine region show comparatively small changes in interannual variability within the time frame considered, with the exception of the summer season, where a substantial increase in interannual variability is simulated by regional climate models. 相似文献
19.
Inter-Annual Variability and Decadal Trends in Alpine Spring Phenology: A Multivariate Analysis Approach 总被引：1，自引：0，他引：1
Plant phenological observations are of increasing value as indicators of climate change and variability. We developed a robust
multispecies estimate for Swiss Alpine spring phenology for the period 1965–2002 by applying empirical orthogonal function
(EOF) analysis on a combination of 15 spring phases. The impact of climate parameters such as temperature and precipitation
on the phenological development was investigated using a multivariate statistical model. This multispecies estimate proved
to be a good approach to assess the pattern of spring appearance during the last 40 years. It revealed an earlier onset of
spring in recent years, mainly since 1988 when a clear shift in spring appearance occurred. The mean overall trend of 1.5
days per decade was clearly driven by winter and spring temperatures whereas precipitation showed no significant influence.
The dominant EOF patterns suggested a general climate forcing for the observed inter-annual variability independent of single
plant phases. A more regional phenology signal was found in the second EOF mode, indicating slightly weaker phenological trends
in southern Switzerland as well as in higher altitudes. Both, temperature and precipitation contributed to this pattern significantly.
Analysis of single phases confirmed the pattern of the multispecies estimate. All species showed trends towards earlier appearance
ranging from −1 to −2.8 days per decade and the appearance dates had a very high covariance with temperature. 相似文献
20.
The possible future impact of anthropogenic forcing upon the circulation of the Mediterranean, and the exchange through the
Strait of Gibraltar is investigated using a Cox-type model of the Mediterranean at 0.25° × 0.25° resolution, forced by “control”
and “greenhouse” scenarios provided by the HadCM2 coupled climate model. The current structure of the Mediterranean forced
by the “control” climate is compared with observations: certain aspects of the present circulation are reproduced, but others
are absent or incorrectly represented. Deficiencies are most probably due to weaknesses in the forcing climatology generated
by the climate model, so some caution must be exercised in interpreting the enhanced greenhouse simulation. Comparison of
the control and greenhouse scenarios suggests that deep-water production in the Mediterranean may be reduced or cease in the
relatively near future. The results also suggest that the Mediterranean outflow, may become warmer and more saline, but less
dense, and hence shallower. The volume of the exchange at the Strait of Gibraltar seems to be relatively insensitive to future
climate change, however. Our results indicate that a parameterisation of Gibraltar exchange and Mediterranean Outflow Water
(MOW) production may be able to provide adequate representation of the changes we observe for the purposes of the current
generation of climate models.
Received: 10 August 1998 / Accepted: 11 October 1999 相似文献