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  • 1
    Electronic Resource
    Electronic Resource
    Sensitivity to prescribed changes in sea surface temperature and sea ice in doubled carbon dioxide experiments (1995)
    Springer
    Climate dynamics 12 (1995), S. 1-20 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Time sclice experiments are performed with the atmospheric GCM ARPEGE, developed at Météo-France, to study the impact to increases in the atmospheric carbon dioxide. This spectral model runs at T42 horizontal resolution with 30 vertical layers including a comprehensive tropospheric and stratospheric resolution and a prognostic parameterization of the ozone mixing ratio. The model is forced in a 5-year control run by climatological SSTs and sea-ice extents in order to obtain an accurate simulation of the present-day climate. Two perturbed runs are performed using SSTs and sea-ice extents for doubled CO2 concentration, obtained from transient runs performed by two coupled atmospheric-oceanic models run at the Max Planck Institute (MPI) in Hamburg and the Hadley Centre (HC). A global surface temperature warming of 1.6 K is obtained with the MPI SST anomalies and 1.9 K with the HC SST anomalies. The precipitation rate increases by 4.2% (and 4.7%). The features obtained in the stratosphere (a cooling increasing with the altitude and an increase in the ozone mixing ratio) are not sensitive to the oceanic forcing. On the contrary, the anomalies in the troposphere such as a warming increasing with altitude, an acceleration of westerly jets and a raised cloud height, depend on the oceanic forcing imposed in the two perturbed runs. Special attention is given to continental areas where the impact of the oceanic forcing is studied over eight regions around the globe. Regions sensitive to oceanic forcing such as Europe are identified in contrast with areas where the patterns are driven by land-surface physical processes, such as over continental Asia. Finally, the Köppen classification is applied to the climate simulated in the three experiments. Both doubled CO2 runs show the same predominance of global warming over precipitation changes in the Kbppen analyses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208759
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A new snow parameterization for the Météo-France climate model (1995)
    Springer
    Climate dynamics 12 (1995), S. 21-35 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Both observational studies and numerical experiments demonstrate the sensitivity of the atmosphere to variations in the extent and mass of snow cover. There is therefore a need for simple but realistic snow parameterizations in forecast and climate models. This study describes a new physically-based snow hydrology for use in the Météo-France climate model, together with the ISBA land-surface scheme. A restricted number of parameters has been added, while preserving a single surface energy budget. The ageing process of the snow pack has been introduced through prognostic equations for snow density and snow albedo. Snowmelt computation has been modified over partially snow-covered and vegetated areas. The new scheme has been validated against field measurements in stand-alone simulations forced by observed meteorological conditions. The results show a strong improvement in the model's performance, thereby suggesting that a simple one-layer snow model is able to reproduce the main physical mechanisms governing the snow pack evolution. Part II of the present study will concern the validation in a 3-D experiment within the Météo-France climate model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00208760
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of the temperate and boreal forests on the Northern Hemisphere climate in the Météo-France climate model (1996)
    Springer
    Climate dynamics 13 (1996), S. 57-74 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. A temperate and boreal deforestation experiment has been performed at Météo-France using the ARPEGE climate model. A first simulation was performed as a control with a present-day vegetation map, and another one with all forests north of 45 °N replaced by meadows. Prescribed monthly mean climatological SSTs were used in both integrations. The ARPEGE climate model includes a physically based land surface scheme, which has been tested both on snowfree and snow-covered sites, and has a relatively high horizontal resolution. Results of the 4-year integrations suggest that forests exert a strong influence on the surface climate of the temperate and boreal regions. Deforestation induces a significant cooling which modifies the atmospheric circulation simulated in the high latitudes, and also in the tropics. The most important impact is observed during the melting season which is delayed by the forest removal. This result is consistent with preliminary stand-alone experiments showing that the atmospheric boundary layer can be heated by the forest, even if the ground is covered by snow. The study confirms that vegetation feedbacks should be included when performing future climate studies such as doubled CO2 experiments, eventhough many uncertainties still remain with regard to other physical aspects of the climate models.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050153
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Sensitivity of the Asian summer monsoon to an anomalous Eurasian snow cover within the Météo-France GCM (1996)
    Springer
    Climate dynamics 12 (1996), S. 449-466 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. Both observational and numerical studies suggest that the Eurasian winter snow cover has a strong influence on the subsequent summer monsoon in Asia. An updated version of the ARPEGE climate model of Météo-France, including a simple but physically-based snow parameterization, is used to test the impact of an increased snow mass prescribed at the beginning of March on the simulated summer monsoon circulation and rainfall. The large-scale features of the Asian monsoon are reproduced in a realistic way in the control integration, which is a necessary premise of such a sensitivity test. In the heavy snow cover experiment, the anomalous persistence of the winter snow pack delays the springtime continental heating. This weakens the thermal low over northern India and Persia as well as the southwesterly winds over the monsoon area. There is also a significant decrease in the rainfall over western India and Bengal-Burma, which usually represent the centers of maximum precipitation. Radiative, turbulence transfer and hydrological processes seem to be involved in the snow-monsoon relationship. The changes in the monsoon precipitation are strongly related to changes in the atmospheric circulation and are not reinforced by a local evaporation/convection feedback in our experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050120
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Response of the Météo-France climate model to changes in CO2 and sea surface temperature (1994)
    Springer
    Climate dynamics 9 (1994), S. 345-362 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The climate response to an increase in carbon dioxide and sea surface temperatures is examined using the Météo-France climate model. This model has a high vertical resolution in the stratosphere and predicts the evolution of the ozone mixing ratio. This quantity is fully interactive with radiation and photochemical production and loss rates are accounted for. Results from a 5-year control run indicate a reasonable agreement with observed climatologies. A 5-year simulation is performed with a doubled CO2 concentration using, as lower boundary conditions, mean surface temperatures anomalies and sea ice limits predicted for the years 56–65 of a 100-year transient simulation performed at Hamburg with a global coupled atmosphere-ocean model. The perturbed simulation produces a global mean surface air warming of 1.4 K and an increase in global mean precipitation rate of 4%. Outside the high latitudes in the Northern Hemisphere, the model simulates a strong cooling in the stratosphere reaching 10 K near the stratopause. Temperature increases are noticed in the lower polar stratosphere of the Northern Hemisphere caused by an intensification in the frequency of sudden warmings in the perturbed simulation. The low and mid-latitude stratospheric cooling leads to an ozone column enhancement of about 5%. Other features present in similar studies are exhibited in the troposphere such as the stronger surface warming over polar regions of the Northern Hemisphere, the summer time soil moisture drying in mid-latitudes and the increase in high convective cloudiness in tropical regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223447
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  • 6
    Electronic Resource
    Electronic Resource
    Response of the Météo-France climate model to changes in CO2 and sea surface temperature (1994)
    Springer
    Climate dynamics 9 (1994), S. 345-362 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. The climate response to an increase in carbon dioxide and sea surface temperatures is examined using the Météo-France climate model. This model has a high vertical resolution in the stratosphere and predicts the evolution of the ozone mixing ratio. This quantity is fully interactive with radiation and photochemical production and loss rates are accounted for. Results from a 5-year control run indicate a reasonable agreement with observed climatologies. A 5-year simulation is performed with a doubled CO2 concentration using, as lower boundary conditions, mean surface temperatures anomalies and sea ice limits predicted for the years 56–65 of a 100-year transient simulation performed at Hamburg with a global coupled atmosphere-ocean model. The perturbed simulation produces a global mean surface air warming of 1.4 K and an increase in global mean precipitation rate of 4%. Outside the high latitudes in the Northern Hemisphere, the model simulates a strong cooling in the stratosphere reaching 10 K near the stratopause. Temperature increases are noticed in the lower polar stratosphere of the Northern Hemisphere caused by an intensification in the frequency of sudden warmings in the perturbed simulation. The low and mid-latitude stratospheric cooling leads to an ozone column enhancement of about 5%. Other features present in similar studies are exhibited in the troposphere such as the stronger surface warming over polar regions of the Northern Hemisphere, the summer time soil moisture drying in mid-latitudes and the increase in high convective cloudiness in tropical regions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050028
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    A new snow parameterization for the Météo-France climate model Part II: validation in a 3-D GCM experiment (1995)
    Springer
    Climate dynamics 12 (1995), S. 37-52 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. Both observational and numerical studies demonstrate the sensitivity of the atmosphere to variations in the extent and mass of snow cover. There is therefore a need for simple but realistic snow parameterizations in forecast and climate models. A new snow hydrology scheme has recently been developed at Météo-France for use in the ARPEGE climate model and has been successfully tested against local field measurements in stand-alone experiments. This study describes the global validation of the parameterization in a 3-year integration for the present-day climate within the T42L30 version of ARPEGE. Results are compared with those from a control simulation and with available observed climatologies, in order to assess the impact of the new snow parameterization on the simulated surface climate. The seasonal cycle of the Northern Hemisphere snow cover is clearly improved when using the new scheme. The snow pack is still slightly overestimated in winter, but its poleward retreat is better reproduced during the melting season. As a consequence, the modified GCM performs well in simulating the springtime continental heating, which may play a strong role in the simulation of the Asian summer monsoon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050093
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    GCM simulation of the Southern Oscillation from 1979–88 (1995)
    Springer
    Climate dynamics 11 (1995), S. 115-128 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The Southern Oscillation (SO) is examined in three 10 year AMIP-type integrations of a 30-level GCM having prescribed monthly mean observed sea surface temperatures for the period January 1979 to December 1988. Three horizontal spectral resolutions of T21, T42 and T79 are investigated and the results are compared with the low-frequency variability, having periods longer than 8 months, in the observed Darwin and Tahiti sea level pressures (SLP) and in the T106 ECMWF analyses from May 1985 to April 1991. Both the ECMWF analyses and the GCM results give unrealistic SLP variability at Tahiti resulting in low Darwin-Tahiti SLP correlations and low S/N ratios for the Tahiti-Darwin SO index. The ECMWF analyses are in particularly poor agreement with the observations during 1987 with anomalously high SLP at Tahiti. Examination of the ECMWF assimilated SSTs, reveals that this may be related to the assimilated SSTs being too cold in the central and eastern equatorial Pacific during mid-1987. The GCM results show the familiar SLP dipole in the tropical Pacific albeit displaced eastwards compared to previous observational studies especially at T42 resolution, thus accounting for the problems at Tahiti which lies near strong gradients in the correlation pattern. Time-longitude diagrams of low-level convergence and correlation maps of upper-level streamfunction suggest that the model is reproducing the SO divergence anomalies although too weakly at T21 resolution and at different longitudinal locations at T42 and T79 resolutions. The time-mean low-level convergences in the GCM simulations give ITCZs and SPCZs in qualitative agreement with the observations with a tendency for increased convergence in the eastern Pacific ITCZ at higher resolution. Longitudinal shifts are not apparent in the time-mean convergence when comparing the GCM results at different resolutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211677
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    Paper (German National Licenses)
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  • 9
    Electronic Resource
    Electronic Resource
    GCM simulation of the Southern Oscillation from 1979–88 (1995)
    Springer
    Climate dynamics 11 (1995), S. 115-128 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract. The Southern Oscillation (SO) is examined in three 10 year AMIP-type integrations of a 30-level GCM having prescribed monthly mean observed sea surface temperatures for the period January 1979 to December 1988. Three horizontal spectral resolutions of T21, T42 and T79 are investigated and the results are compared with the low-frequency variability, having periods longer than 8 months, in the observed Darwin and Tahiti sea level pressures (SLP) and in the T106 ECMWF analyses from May 1985 to April 1991. Both the ECMWF analyses and the GCM results give unrealistic SLP variability at Tahiti resulting in low Darwin-Tahiti SLP correlations and low S/N ratios for the Tahiti-Darwin SO index. The ECMWF analyses are in particularly poor agreement with the observations during 1987 with anomalously high SLP at Tahiti. Examination of the ECMWF assimilated SSTs, reveals that this may be related to the assimilated SSTs being too cold in the central and eastern equatorial Pacific during mid-1987. The GCM results show the familiar SLP dipole in the tropical Pacific albeit displaced eastwards compared to previous observational studies especially at T42 resolution, thus accounting for the problems at Tahiti which lies near strong gradients in the correlation pattern. Time-longitude diagrams of low-level convergence and correlation maps of upper-level streamfunction suggest that the model is reproducing the SO divergence anomalies although too weakly at T21 resolution and at different longitudinal locations at T42 and T79 resolutions. The time-mean low-level convergences in the GCM simulations give ITCZs and SPCZs in qualitative agreement with the observations with a tendency for increased convergence in the eastern Pacific ITCZ at higher resolution. Longitudinal shifts are not apparent in the time-mean convergence when comparing the GCM results at different resolutions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003820050064
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    Sensitivity of the Asian summer monsoon to an anomalous Eurasian snow cover within the Météo-France GCM (1996)
    Springer
    Climate dynamics 12 (1996), S. 449-466 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Both observational and numerical studies suggest that the Eurasian winter snow cover has a strong influence on the subsequent summer monsoon in Asia. An updated version of the ARPEGE climate model of Meteo-France, including a simple but physically-based snow parameterization, is used to test the impact of an increased snow mass prescribed at the beginning of March on the simulated summer monsoon circulation and rainfall. The large-scale features of the Asian monsoon are reproduced in a realistic way in the control integration, which is a necessary premise of such a sensitivity test. In the heavy snow cover experiment, the anomalous persistence of the winter snow pack delays the springtime continental heating. This weakens the thermal low over northern India and Persia as well as the southwesterly winds over the monsoon area. There is also a significant decrease in the rainfall over western India and Bengal-Burma, which usually represent the centers of maximum precipitation. Radiative, turbulence transfer and hydrological processes seem to be involved in the snow-monsoon relationship. The changes in the monsoon precipitation are strongly related to changes in the atmospheric circulation and are not reinforced by a local evaporation/convection feedback in our experiment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02346818
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    Paper (German National Licenses)
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