共查询到20条相似文献,搜索用时 46 毫秒
1.
2.
Modelling the response of glaciers to climate change by applying volume-area scaling in combination with a high resolution GCM 总被引:4,自引:0,他引:4
A seasonally and regionally differentiated glacier model is used to estimate the contribution that glaciers are likely to
make to global sea level rise over a period of 70 years. A high resolution general circulation model (ECHAM4 T106) is used
to estimate temperature and precipitation changes for a doubled CO2 climate and serves as input for the glacier model. Volume-area relations are used to take into account the reduction of glacier
area resulting from greenhouse warming. Each glacieriated region has a specified glacier size distribution, defined by the
number of glaciers in a size class and a mean area. Changes in glacier volume are calculated by a precipitation dependent
mass balance sensitivity. The model predicts a global sea level rise of 57 mm over a period of 70 years. This corresponds
to a sensitivity of 0.86 mm yr−1K−1. Assuming a constant glacier area as done in earlier work leads to an overestimation of 19% for the contribution to sea level
rise.
Received: 16 August 2000 / Accepted: 21 May 2001 相似文献
3.
A. P. Dimri 《Climate Dynamics》2009,32(4):565-574
An attempt is made to integrate subgrid scale scheme on the work of Dimri and Ganju (Pure Appl Geophys 167:1–24, 2007) to understand the overall nature of surface heterogeneity and landuse variability along with resolvable finescale micro/meso
scale circulation over the Himalayan region, which is having different altitudes and orientations causing prevailing weather
conditions to be complex. This region receives large amount of precipitation due to eastward moving low-pressure synoptic
weather systems, called western disturbances, during winter season (December, January, February—DJF). Surface heterogeneity
and landuse variability of the Himalayan region gives rise to numerous micro/meso scale circulation along with prevailing
weather. Therefore, in the present work, a mosaic type parameterization of subgrid scale topography and landuse within a framework
of a regional climate model (RegCM3) is extended to study interseasonal variability of surface climate during a winter season
(October 1999–March 2000) of the work of Dimri and Ganju (Pure Appl Geophys 167:1–24, 2007). In this scheme, meteorological variables are disaggregated from the coarse grid to the fine grid, land surface calculations
are then performed separately for each subgrid cell, and surface fluxes are calculated and reaggregated onto the coarse grid
cell for input to the atmospheric model. By doing so, resolvable finescale structures due to surface heterogeneity and landuse
variability at coarse grid are subjected to parameterize at regular finescale surface subgrid. Model simulations show that
implementation of subgrid scheme presents more realistic simulation of precipitation and surface air temperature. Influence
of topographic elevation and valleys is better represented in the scheme. Overall, RegCM3 with subgrid scheme provides more
accurate representation of resolvable finescale atmospheric/surface circulations that results in explaining mean variability
in a better way. 相似文献
4.
In this study it is shown that the availability of a very high resolution dataset of land surface characteristics leads to the improvement of a surface runoff parameterization scheme. The improved parameterization scheme was developed for application in global and regional climate models and is a further development of the Arno scheme that is widely used in climate models. Here, surface runoff is computed as infiltration excess from a "bucket" type reservoir which takes the subgrid variability of soil saturation within a model gridbox into account. Instead of prescribing a distribution of subgrid scale soil water capacities as in the original Arno scheme, the array of high resolution soil water capacities taken from a global 1 km dataset of land surface parameters is used to obtain individual fractional saturation curves for each model gridbox. From each saturation curve, the three parameters (a shape parameter describing the shape of the subgrid distribution of soil water capacities, subgrid minimum and maximum soil water capacity) required in the modified formulation of the scheme are derived via optimization. As in the original Arno scheme applied in the ECHAM general circulation model and the REMO regional climate model, topography variations will influence the distribution of saturated subgrid areas within a model gridbox. At most gridboxes the net effect of these changes is such that more runoff is produced for high soil water contents and less runoff for low soil water contents. A validation of simulated discharge computed with a simplified land surface scheme applied to reanalysis data of the European Centre for Medium-Range Weather Forecasts and a hydrological discharge model has shown that these changes lead to a more realistic simulation of the annual cycle of discharge for several catchments. In particular this could be shown for the Yangtze Kiang and Amur catchments where adequate input data are available. 相似文献
5.
Assessments of the impacts of climate change typically require information at scales of 10 km or less. Such a resolution in global climate simulations is unlikely for at least two decades. We have developed an alternative to explicit resolution that provides a framework for meeting the needs of climate change impact assessment much sooner. We have applied to a global climate model a physically based subgrid-scale treatment of the influence of orography on temperature, clouds, precipitation, and land surface hydrology. The treatment represents subgrid variations in surface elevation in terms of fractional area distributions of discrete elevation classes. For each class it calculates the height rise/descent of air parcels traveling through the grid cell, and applies the influence of the rise/descent to the temperature and humidity profiles of the elevation class. Cloud, radiative, and surface processes are calculated separately for each elevation class using the same physical parametrizations used by the model without the subgrid orography parametrization. The simulated climate fields for each elevation class can then be distributed in post-processing according to the spatial distribution of surface elevation within each grid cell. Parallel 10-year simulations with and without the subgrid treatment have been performed. The simulated temperature, precipitation and snow water are mapped to 2.5-minute (~5 km) resolution and compared with gridded analyses of station measurements. The simulation with the subgrid scheme produces a much more realistic distribution of snow water and significantly more realistic distributions of temperature and precipitation than the simulation without the subgrid scheme. Moreover, the 250-km grid cell means of most other fields are virtually unchanged by the subgrid scheme. This suggests that the tuning of the climate model without the subgrid scheme is also applicable to the model with the scheme. 相似文献
6.
Impacts of Internally and Externally Mixed Anthropogenic Sulfate and Carbonaceous Aerosols on East Asian Climate 总被引:1,自引:0,他引:1
下载免费PDF全文
![点击此处可从《Acta Meteorologica Sinica》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A coupled regional climate and aerosol-chemistry model, RIEMS 2.0 (Regional Integrated Environmental Model System for Asia),
in which anthropogenic sulfate, black carbon, and organic carbon were assumed to be externally mixed (EM), internally mixed
(IM) or partially internally mixed (IEM), was used to simulate the impacts of these anthropogenic aerosols on East Asian climate
for the entire year of 2006. The distributions of aerosol mass concentration, radiative forcing and hence the surface air
temperature and precipitation variations under three mixing assumptions of aerosols were analyzed. The results indicated that
the mass concentration of sulfate was sensitive to mixing assumptions, but carbonaceous aerosols were much less sensitive
to the mixing types. Modeled results were compared with observations in a variety of sites in East Asia. It was found that
the simulated concentrations of sulfate and carbonaceous aerosols were in accord with the observations in terms of magnitude.
The simulated aerosol concentrations in IM case were closest to observation results. The regional average column burdens of
sulfate, black carbon, and organic carbon, if internally mixed, were 11.49, 0.47, and 2.17 mg m−2, respectively. The radiative forcing of anthropogenic aerosols at the top of the atmosphere increased from −1.27 (EM) to
−1.97 W m−2 (IM) while the normalized radiative forcing (NRF) decreased from −0.145 (EM) to −0.139 W mg−1 (IM). The radiative forcing and NRF were −1.82 W m−2 and −0.141 W mg−1 for IEM, respectively. The surface air temperature changes over the domain due to the anthropogenic sulfate and carbonaceous
aerosols were −0.067, −0.078, and −0.072 K, with maxima of −0.47, −0.50, and −0.49 K, for EM, IM, and IEM, respectively. Meanwhile,
the annual precipitation variations were −8.0 (EM), −20.6 (IM), and −21.9 mm (IEM), with maxima of 148, 122, and 102 mm, respectively,
indicating that the climate effects were stronger if the sulfate and carbonaceous aerosols were internally mixed. 相似文献
7.
A subgrid parameterization of orographic precipitation 总被引:6,自引:0,他引:6
Summary Estimates of the impact of global climate change on land surface hydrology require climate information on spatial scales far smaller than those explicitly resolved by global climate models of today and the foreseeable future. To bridge the gap between what is required and what is resolved, we propose a subgrid-scale parameterization of the influence of topography on clouds, precipitation, and land surface hydrology. The parameterization represents subgrid variations in surface elevation in terms of probability distributions of discrete elevation classes. Separate cloud, radiative, and surface processes are calculated for each elevation class. Rainshadow effects are not treated by the parameterization; they have to be explicitly resolved by the host model. The simulated surface temperature, precipitation, and snow cover for each elevation class are distributed to different geographical locations according to the spatial distribution of surface elevation within each grid cell.The subgrid parameterization has been implemented in the Pacific Northwest Laboratory's climate version of the Penn State/NCAR Mesoscale Model. The scheme is evaluated by driving the regional climate model with observed lateral boundary conditions for the Pacific Northwest and comparing simulated fields with surface observations. The method yields more realistic spatial distributions of precipitation and snow cover in mountainous areas and is considerably more computationally efficient than achieving high resolution by the use of nesting in the regional climate model.With 17 Figures 相似文献
8.
The aim of this work is to assess potential future Antarctic surface mass balance changes, the underlying mechanisms, and the impact of these changes on global sea level. To this end, this paper presents simulations of the Antarctic climate for the end of the twentieth and twenty-first centuries. The simulations were carried out with a stretched-grid atmospheric general circulation model, allowing for high horizontal resolution (60 km) over Antarctica. It is found that the simulated present-day surface mass balance is skilful on continental scales. Errors on regional scales are moderate when observed sea surface conditions are used; more significant regional biases appear when sea surface conditions from a coupled model run are prescribed. The simulated Antarctic surface mass balance increases by 32 mm water equivalent per year in the next century, corresponding to a sea level decrease of 1.2 mm year−1 by the end of the twenty-first century. This surface mass balance increase is largely due to precipitation changes, while changes in snow melt and turbulent latent surface fluxes are weak. The temperature increase leads to an increased moisture transport towards the interior of the continent because of the higher moisture holding capacity of warmer air, but changes in atmospheric dynamics, in particular off the Antarctic coast, regionally modulate this signal. 相似文献
9.
Heidrun Matthes Annette Rinke Paul A. Miller Peter Kuhry Klaus Dethloff Annett Wolf 《Climatic change》2012,111(2):197-214
This paper discusses the effects of vegetation cover and soil parameters on the climate change projections of a regional climate
model over the Arctic domain. Different setups of the land surface model of the regional climate model HIRHAM were realized
to analyze differences in the atmospheric circulation caused by (1) the incorporation of freezing/thawing of soil moisture,
(2) the consideration of top organic soil horizons typical for the Arctic and (3) a vegetation shift due to a changing climate.
The largest direct thermal effect in 2 m air temperature was found for the vegetation shift, which ranged between −1.5 K and
3 K. The inclusion of a freeze/thaw scheme for soil moisture shows equally large sensitivities in spring over cool areas with
high soil moisture content. Although the sensitivity signal in 2 m air temperature for the experiments differs in amplitude,
all experiments show changes in mean sea level pressure (mslp) and geopotential height (z) throughout the troposphere of similar
magnitude (mslp: −2 hPa to 1.5 hPa, z: −15 gpm to 5 gpm). This points to the importance of dynamical feedbacks within the
atmosphere-land system. Land and soil processes have a distinct remote influence on large scale atmospheric circulation patterns
in addition to their direct, regional effects. The assessment of induced uncertainties due to the changed implementations
of land surface processes discussed in this study demonstrates the need to take all those processes for future Arctic climate
projections into account, and demonstrates a clear need to include similar implementations in regional and global climate
models. 相似文献
10.
Pessacg Natalia Flaherty Silvia Solman Silvina Pascual Miguel 《Theoretical and Applied Climatology》2020,140(3):807-822
The current study presents an assessment of the impact of climate change on water yield, one of the main hydrological ecosystem services, in northern Patagonia. The outputs of regional climate models from the CORDEX Project for South America were used to drive the InVEST water yield model. CORDEX regional climate models project for the far future (2071–2100) an increase in temperature higher than 1.5 °C and a precipitation decrease ranging from − 10 to − 30% for the study area. The projected warmer and dryer climate emerges as a robust signal based on model agreement and on consistent physical drivers of these changes. Moreover, both the projected increase in evapotranspiration and the decrease in precipitation contribute to a strong decrease in water yield of around − 20 to − 40% in the headwaters of northern Patagonian watersheds. Comparison of the results in the two basins reveals that the land cover may be considered a buffer of water yield changes and highlights the key role of protected areas in reducing the vulnerability of water resources to climate change. 相似文献
11.
Daniel Steiner Andreas Pauling Samuel U. Nussbaumer Atle Nesje Jürg Luterbacher Heinz Wanner Heinz J. Zumbühl 《Climatic change》2008,90(4):413-441
A nonlinear backpropagation network (BPN) has been trained with high-resolution multiproxy reconstructions of temperature
and precipitation (input data) and glacier length variations of the Alpine Lower Grindelwald Glacier, Switzerland (output
data). The model was then forced with two regional climate scenarios of temperature and precipitation derived from a probabilistic
approach: The first scenario (“no change”) assumes no changes in temperature and precipitation for the 2000–2050 period compared
to the 1970–2000 mean. In the second scenario (“combined forcing”) linear warming rates of 0.036–0.054°C per year and changing
precipitation rates between −17% and +8% compared to the 1970–2000 mean have been used for the 2000–2050 period. In the first
case the Lower Grindelwald Glacier shows a continuous retreat until the 2020s when it reaches an equilibrium followed by a
minor advance. For the second scenario a strong and continuous retreat of approximately −30 m/year since the 1990s has been
modelled. By processing the used climate parameters with a sensitivity analysis based on neural networks we investigate the
relative importance of different climate configurations for the Lower Grindelwald Glacier during four well-documented historical
advance (1590–1610, 1690–1720, 1760–1780, 1810–1820) and retreat periods (1640–1665, 1780–1810, 1860–1880, 1945–1970). It
is shown that different combinations of seasonal temperature and precipitation have led to glacier variations. In a similar
manner, we establish the significance of precipitation and temperature for the well-known early eighteenth century advance
and the twentieth century retreat of Nigardsbreen, a glacier in western Norway. We show that the maritime Nigardsbreen Glacier
is more influenced by winter and/or spring precipitation than the Lower Grindelwald Glacier. 相似文献
12.
Summary Climatic changes of summer temperature and precipitation in the greater Alpine region are assessed by using statistical-dynamical
downscaling. The downscaling procedure is applied to two 30-year periods (1971–2000 and 2071–2100, summer months only) taken
from the results of a transient coupled ocean/atmosphere climate scenario simulation with increasing greenhouse gas concentrations.
The downscaling results for the present-day climate are compared with observations. The estimated regional climate change
during the next 100 years shows a general warming. The mean summer temperatures increase by 3 to 5 Kelvin. The most intense
climatic warming is predicted in the western parts of the Alps. The amount of summer precipitation decreases in most parts
of central Europe by more than 20 percent. Increasing precipitation is simulated only over the Adriatic area and parts of
eastern central Europe.
The results are compared with observed climate trends for the last decades and results of other regional climate change estimations.
The observed trends and the majority of the simulated trends (including ours) have a number of common features. However, there
are also climate change estimates of other groups which completely contradict our results.
Received April 8, 1999 Revised November 16, 1999 相似文献
13.
Summary We use the regional climate model RegCM nested within time-slice atmospheric general circulation model experiments to investigate
the possible changes of intense and extreme precipitation over the French Maritime Alps in response to global climate change.
This is a region with complex orography where heavy and/or extended precipitation episodes induced catastrophic floods during
the last decades. Output from a 30-year simulation of present-day climate (1961–1990) is first analysed and compared with
NCEP reanalysed 700 hPa geopotential heights (Z700) and daily precipitation observations from the Alpine Precipitation Climatology
(1966–1999). Two simulations under forcing from the A2 and B2 IPCC emission scenarios for the period 2071–2100 are used to
investigate projected changes in extreme precipitation for our region of interest. In general, the model overestimates the
annual cycle of precipitation. The climate change projections show some increase of precipitation, mostly outside the warm
period for the B2 scenario, and some increase in the variability of the annual precipitation totals for the A2 scenario. The
model reproduces the main observed patterns of the spatial leading EOFs in the Z700 field over the Atlantic-European domain.
The simulated large scale circulation (LSC) variability does not differ significantly from that of the reanalysis data provided
the EOFs are computed on the same domain. Two similar clusters of LSC corresponding to heavy precipitation days were identified
for both simulated and observed data and their patterns do not change significantly in the climate change scenarios. The analysis
of frequency histograms of extreme indices shows that the control simulation systematically underestimates the observed heavy
precipitation expressed as the 90th percentile of rainday amounts in all seasons except summer and better reproduces the greatest 5-day precipitation accumulation.
The main hydrological changes projected for the Maritime Alps consist of an increase of most intense wet spell precipitation
during winters for both scenarios and during autumn for the B2 scenario. Case studies of heavy precipitation events show that
the RegCM is capable to reproduce the physical mechanisms responsible for heavy precipitation over our region of interest. 相似文献
14.
G. Heinemann 《Theoretical and Applied Climatology》2006,83(1-4):35-50
Summary The dynamical effect of land surface heterogeneity on heat fluxes in the atmospheric boundary layer (ABL) is investigated
using numerical simulations with a non-hydrostatic model over a wide range of grid resolutions. It is commonly assumed that
mesoscale or dynamical fluxes associated with mesoscale and convective circulations simulated by a high-resolution model (subgrid
(SG) model) on the subgrid scale of a climate model (large-scale (LS) model) represent additional processes in the ABL, which
are not considered by the turbulence scheme of the LS-model, and which can be parameterized using the SG-model. The present
study investigates the usefulness of this methodology for small-scale and large-scale idealized heterogeneities using a SG-model
resolving mesoscale or even microscale circulations to compute the mesoscale fluxes on the scale of the LS-model. It is shown
that the dynamical transports as derived from the SG-model should not be used to correct the parameterized turbulent fluxes
of the LS-model. The reason is that the subgrid circulations simulated by the SG-model interact with the fields of wind and
scalars in the ABL, which results in reduced turbulent fluxes in the ABL. Thus the methodology of previous studies to use
mesoscale/dynamical fluxes for the correction of flux profiles simulated by climate models seems to be questionable. 相似文献
15.
Snow pack in the Swiss Alps under changing climatic conditions: an empirical approach for climate impacts studies 总被引:1,自引:0,他引:1
Summary ?In many instances, snow cover and duration are a major controlling factor on a range of environmental systems in mountain
regions. When assessing the impacts of climatic change on mountain ecosystems and river basins whose origin lie in the Alps,
one of the key controls on such systems will reside in changes in snow amount and duration. At present, regional climate models
or statistical downscaling techniques, which are the principal methods applied to the derivation of climatic variables in
a future, changing climate, do not provide adequate information at the scales required for investigations in which snow is
playing a major role. A study has thus been undertaken on the behavior of snow in the Swiss Alps, in particular the duration
of the seasonal snow-pack, on the basis of observational data from a number of Swiss climatological stations. It is seen that
there is a distinct link between snow-cover duration and height (i.e., temperature), and that this link has a specific “signature”
according to the type of winter. Milder winters are associated with higher precipitation levels than colder winters, but with
more solid precipitation at elevations exceeding 1,700–2,000 m above sea-level, and more liquid precipitation below. These
results can be combined within a single diagram, linking winter minimum temperature, winter precipitation, and snow-cover
duration. The resulting contour surfaces can then be used to assess the manner in which the length of the snow-season may
change according to specified shifts in temperature and precipitation. While the technique is clearly empirical, it can be
combined with regional climate model information to provide a useful estimate of the length of the snow season with snow cover,
for various climate-impacts studies.
Received May 14, 2002; revised August 12, 2002; accepted August 17, 2002 相似文献
16.
Ian M. Howat Slawek Tulaczyk Philip Rhodes Kevin Israel Mark Snyder 《Climate Dynamics》2007,28(1):85-98
Temperature is often seen as the dominant control on inter-decadal glacier volume changes. However, despite regional warming over the past half-century, the glaciers of Mount Shasta have continued to expand following a contraction during a prolonged drought in the early twentieth century, indicating a greater sensitivity to precipitation than temperature. We use the 110 year record of fluctuations in Mount Shasta’s glaciers and climate to calibrate numerical glacier models of the two largest glaciers. The reconstructed balance and volume histories show a much greater correlation to precipitation than temperature and significant correlation to oscillatory modes of Pacific Ocean climate. An approximately 20% increase in precipitation is needed for every 1°C increase in temperature to maintain stability. Under continued historical trends, oscillations in climate modes and random variability will dominate inter-decadal variability in ice volume. Under the strong warming trend predicted by a regional climate model, the temperature trend will be the dominant forcing resulting in near total loss of Mount Shasta’s glaciers by the end of the twenty-first century.Electronic Supplementary Material Supplementary material is available to authorised users in the online version of this article at . 相似文献
17.
Contribution of glacier melt to sea-level rise since AD 1865: a regionally differentiated calculation 总被引:6,自引:0,他引:6
The contribution of glacier melt, including the Greenland ice-sheet, to sea-level change since AD 1865 is estimated on the
basis of modelled sensitivity of glacier mass balance to climate change and historical temperature data. Calculations are
done in a regionally differentiated manner to overcome the inhomogeneity of the global distribution of glaciers. A distinction
is made between changes in summer temperature and in temperature over the rest of the year. Our best estimate of the ice melt
in the period 1865–1990 in terms of sea-level change equivalent is 5.7 cm (2.7 cm for glaciers and 3.0 cm for the Greenland
ice-sheet). Additional calculations show that simpler methods, like using annual or even global mean temperature anomaly give
estimates that differ by up to 55%. Consequently, a regionally differentiating approach is advised for making projections
of glacier melt with GCM output.
Received: 6 December 1996/Accepted: 30 May 1997 相似文献
18.
Parameterization of the thermal impacts of sub-grid orography on numerical modeling of the surface energy budget over East Asia 总被引:4,自引:0,他引:4
Summary A parameterization scheme for the thermal effects of subgrid scale orography is incorporated into a regional climate model
(developed at Nanjing University) and its impact on modeling of the surface energy budget over East Asia is evaluated. This
scheme includes the effect of terrain slope and orientation on the computation of solar and infrared radiation fluxes at the
surface, as well as the surface sensible and latent heat fluxes. Calculations show that subgrid terrain parameters alter the
diurnal cycle and horizontal distributions of surface energy budget components. This effect becomes more significant with
increased terrain slope, especially in winter. Due to the inclusion of the subgrid topography, the surface area of a model
grid box changes over complex terrain areas. Numerical experiments, with and without the subgrid scale topography scheme,
show that the parameterization scheme of subgrid scale topography modifies the distribution of the surface energy budget and
surface temperature around the Tibetan Plateau. Comparisons with observations indicate that the subgrid topography scheme,
implemented in the climate model, reproduces the observed detailed spatial temperature structures at the eastern edge of the
Tibetan Plateau and reduces the tendency to overestimate precipitation along the southern coastal areas of China in summer. 相似文献
19.
River discharge and freshwater runoff to the Barents Sea under present and future climate conditions
River discharge forms a major freshwater input into the Arctic Ocean, and as such it has the potential to influence the oceanic
circulation. As the hydrology of Arctic river basins is dominated by cryospheric processes such as snow accumulation and snowmelt,
it may also be highly sensitive to a change in climate. Estimating the water balance of these river basins is therefore important,
but it is complicated by the sparseness of observations and the large uncertainties related to the measurement of snowfalls.
This study aims at simulating the water balance of the Barents Sea drainage basin in Northern Europe under present and future
climate conditions. We used a regional climate model to drive a large-scale hydrological model of the area. Using simulated
precipitation derived from a climate model led to an overestimation of the annual discharge in most river basins, but not
in all. Under the B2 scenario of climate change, the model simulated a 25% increase in freshwater runoff, which is proportionally
larger than the projected precipitation increase. As the snow season is 30–50 day shorter, the spring discharge peak is shifted
by about 2–3 weeks, but the hydrological regime of the rivers remains dominated by snowmelt. 相似文献
20.
A scenario of the Mediterranean Sea is performed for the twenty-first century based on an ocean modelling approach. A climate change IPCC-A2 scenario run with an atmosphere regional climate model is used to force a Mediterranean Sea high-resolution ocean model over the 1960–2099 period. For comparison, a control simulation as long as the scenario has also been carried out under present climate fluxes. This control run shows air–sea fluxes in agreement with observations, stable temperature and salinity characteristics and a realistic thermohaline circulation simulating the different intermediate and deep water masses described in the literature. During the scenario, warming and saltening are simulated for the surface (+3.1°C and + 0.48 psu for the Mediterranean Sea at the end of the twenty-first century) and for the deeper layers (+1.5°C and + 0.23 psu on average). These simulated trends are in agreement with observed trends for the Mediterranean Sea over the last decades. In addition, the Mediterranean thermohaline circulation (MTHC) is strongly weakened at the end of the twenty-first century. This behaviour is mainly due to the decrease in surface density and so the decrease in winter deep-water formation. At the end of the twenty-first century, the MTHC weakening can be evaluated as −40% for the intermediate waters and −80% for the deep circulation with respect to present-climate conditions. The characteristics of the Mediterranean Outflow Waters flowing into the Atlantic Ocean are also strongly influenced during the scenario. 相似文献