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Mathematical Geosciences - The majority of popular methods of prospectivity modeling refer to the raster mode of digital two-dimensional map images or three-dimensional geomodels, thus requiring a... 相似文献
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Climate Dynamics - In which direction is the influence larger: from the Arctic to the mid-latitudes or vice versa? To answer this question, CO2 concentrations have been regionally increased in... 相似文献
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Future extreme events in European climate: an exploration of regional climate model projections 总被引：7，自引：0，他引：7
Martin Beniston David B. Stephenson Ole B. Christensen Christopher A. T. Ferro Christoph Frei Stéphane Goyette Kirsten Halsnaes Tom Holt Kirsti Jylhä Brigitte Koffi Jean Palutikof Regina Schöll Tido Semmler Katja Woth 《Climatic change》2007,81(1):71-83
This paper compares how well satellite versus weather station measurements of climate predict agricultural performance in
Brazil, India, and the United States. Although weather stations give accurate measures of ground conditions, they entail sporadic
observations that require interpolation where observations are missing. In contrast, satellites have trouble measuring some
ground phenomenon such as precipitation but they provide complete spatial coverage of various parameters over a landscape.
The satellite temperature measurements slightly outperform the interpolated ground station data but the precipitation ground
measurements generally outperform the satellite surface wetness index. In India, the surface wetness index outperforms station
precipitation but this may be reflecting irrigation, not climate. The results suggest that satellites provide promising measures
of temperature but that ground station data may still be preferred for measuring precipitation in rural settings. 相似文献
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EC-Earth V2.2: description and validation of a new seamless earth system prediction model 总被引：2，自引：2，他引：0
W. Hazeleger X. Wang C. Severijns S. ?tef?nescu R. Bintanja A. Sterl K. Wyser T. Semmler S. Yang B. van den Hurk T. van Noije E. van der Linden K. van der Wiel 《Climate Dynamics》2012,39(11):2611-2629
EC-Earth, a new Earth system model based on the operational seasonal forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF), is presented. The performance of version 2.2 (V2.2) of the model is compared to observations, reanalysis data and other coupled atmosphere–ocean-sea ice models. The large-scale physical characteristics of the atmosphere, ocean and sea ice are well simulated. When compared to other coupled models with similar complexity, the model performs well in simulating tropospheric fields and dynamic variables, and performs less in simulating surface temperature and fluxes. The surface temperatures are too cold, with the exception of the Southern Ocean region and parts of the Northern Hemisphere extratropics. The main patterns of interannual climate variability are well represented. Experiments with enhanced CO2 concentrations show well-known responses of Arctic amplification, land-sea contrasts, tropospheric warming and stratospheric cooling. The global climate sensitivity of the current version of EC-Earth is slightly less than 1?K/(W?m?2). An intensification of the hydrological cycle is found and strong regional changes in precipitation, affecting monsoon characteristics. The results show that a coupled model based on an operational seasonal prediction system can be used for climate studies, supporting emerging seamless prediction strategies. 相似文献
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Andreas Sterl Richard Bintanja Laurent Brodeau Emily Gleeson Torben Koenigk Torben Schmith Tido Semmler Camiel Severijns Klaus Wyser Shuting Yang 《Climate Dynamics》2012,39(11):2631-2657
EC-Earth is a newly developed global climate system model. Its core components are the Integrated Forecast System (IFS) of the European Centre for Medium Range Weather Forecasts (ECMWF) as the atmosphere component and the Nucleus for European Modelling of the Ocean (NEMO) developed by Institute Pierre Simon Laplace (IPSL) as the ocean component. Both components are used with a horizontal resolution of roughly one degree. In this paper we describe the performance of NEMO in the coupled system by comparing model output with ocean observations. We concentrate on the surface ocean and mass transports. It appears that in general the model has a cold and fresh bias, but a much too warm Southern Ocean. While sea ice concentration and extent have realistic values, the ice tends to be too thick along the Siberian coast. Transports through important straits have realistic values, but generally are at the lower end of the range of observational estimates. Exceptions are very narrow straits (Gibraltar, Bering) which are too wide due to the limited resolution. Consequently the modelled transports through them are too high. The strength of the Atlantic meridional overturning circulation is also at the lower end of observational estimates. The interannual variability of key variables and correlations between them are realistic in size and pattern. This is especially true for the variability of surface temperature in the tropical Pacific (El Ni?o). Overall the ocean component of EC-Earth performs well and helps making EC-Earth a reliable climate model. 相似文献
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The impact of Arctic sea ice on the Arctic energy budget and on the climate of the Northern mid-latitudes 总被引：1，自引：1，他引：0
The atmospheric general circulation model EC-EARTH-IFS has been applied to investigate the influence of both a reduced and a removed Arctic sea ice cover on the Arctic energy budget and on the climate of the Northern mid-latitudes. Three 40-year simulations driven by original and modified ERA-40 sea surface temperatures and sea ice concentrations have been performed at T255L62 resolution, corresponding to 79?km horizontal resolution. Simulated changes between sensitivity and reference experiments are most pronounced over the Arctic itself where the reduced or removed sea ice leads to strongly increased upward heat and longwave radiation fluxes and precipitation in winter. In summer, the most pronounced change is the stronger absorption of shortwave radiation which is enhanced by optically thinner clouds. Averaged over the year and over the area north of 70° N, the negative energy imbalance at the top of the atmosphere decreases by about 10?W/m2 in both sensitivity experiments. The energy transport across 70° N is reduced. Changes are not restricted to the Arctic. Less extreme cold events and less precipitation are simulated in sub-Arctic and Northern mid-latitude regions in winter. 相似文献
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‘Modelling the Arctic Boundary Layer: An Evaluation of Six Arcmip Regional-Scale Models using Data from the Sheba Project’ 总被引：3，自引：0，他引：3
Michael Tjernström Mark Žagar Gunilla Svensson John J. Cassano Susanne Pfeifer Annette Rinke Klaus Wyser Klaus Dethloff Colin Jones Tido Semmler Michael Shaw 《Boundary-Layer Meteorology》2005,117(2):337-381
A primary climate change signal in the central Arctic is the melting of sea ice. This is dependent on the interplay between
the atmosphere and the sea ice, which is critically dependent on the exchange of momentum, heat and moisture at the surface.
In assessing the realism of climate change scenarios it is vital to know the quality by which these exchanges are modelled
in climate simulations. Six state-of-the-art regional-climate models are run for one year in the western Arctic, on a common
domain that encompasses the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment ice-drift track. Surface variables,
surface fluxes and the vertical structure of the lower troposphere are evaluated using data from the SHEBA experiment. All
the models are driven by the same lateral boundary conditions, sea-ice fraction and sea and sea-ice surface temperatures.
Surface pressure, near-surface air temperature, specific humidity and wind speed agree well with observations, with a falling
degree of accuracy in that order. Wind speeds have systematic biases in some models, by as much as a few metres per second.
The surface radiation fluxes are also surprisingly accurate, given the complexity of the problem. The turbulent momentum flux
is acceptable, on average, in most models, but the turbulent heat fluxes are, however, mostly unreliable. Their correlation
with observed fluxes is, in principle, insignificant, and they accumulate over a year to values an order of magnitude larger
than observed. Typical instantaneous errors are easily of the same order of magnitude as the observed net atmospheric heat
flux. In the light of the sensitivity of the atmosphere–ice interaction to errors in these fluxes, the ice-melt in climate
change scenarios must be viewed with considerable caution. 相似文献
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