A new snow parameterization for the Météo-France climate model     

H. Douville  J. -F. Royer  J. -F. Mahfouf 《Climate Dynamics》1995,12(1):37-52

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.  相似文献   

11 Ma以来努比亚相对南极洲的运动     

Jean-Yves Royer  徐明芝 《海洋地质前沿》2007,23(1):13-16

虽然非洲与南极洲之间的相对运动已经有很长的研究历史(如Le Pechon和Heirtzler,1968),但是只是最近才弄清了努比亚(西非)-南极洲和索马里(东非)-南极洲运动之间的区别.DeMets等(1988)认为西南印度洋海岭的数据不能说明努比亚-南极洲和索马里-南极洲运动;Jestin等(1994)证实了这个结果,认为努比亚-索马里边界与西南印度洋海岭呈相交状态.  相似文献   

Spatialization of the SNOWPACK snow model for the Canadian Arctic to assess Peary caribou winter grazing conditions     

F. Ouellet  A. Langlois  E. A. Blukacz-Richards  C. A. Johnson  A. Royer  E. Neave 《自然地理学》2017,38(2):143-158

Abstract

Peary caribou is the northernmost designatable unit for caribou species, and its population has declined by about 70% over the last three generations. The Committee on the Status of Endangered Wildlife in Canada identified difficult grazing conditions through the snow cover as being the most significant factor contributing to this decline. This study focuses on a spatially explicit assessment tool using snow model simulations (Swiss SNOWPACK model driven in an off-line mode by spatialized meteorological forcing data generated by the Canadian Regional Climate Model) to characterize snow conditions for Peary caribou grazing in the Canadian Arctic. The life cycle of Peary caribou has been subdivided into three critical periods: summer foraging and fall breeding (July–October), winter foraging (November–March), and spring calving (April–June). Winter snow conditions are analyzed and snow simulations compared to Peary caribou island counts to identify a snow parameter that could potentially act as a proxy for grazing conditions and explain fluctuations in Peary caribou numbers. This analysis concludes that caribou counts are affected by simulated snow density values >300 kg m^?3. A software tool mapping possibly favorable and unfavorable grazing conditions based on snow is proposed at a regional scale across the Canadian Arctic Archipelago. Specific output examples are given to show the utility of the tool, mapping pixels with cumulative snow thickness above densities of 300 kg m^?3, where cumulative seasonal thicknesses >7000 cm are considered unfavorable.  相似文献   

Variability and change in the Canadian cryosphere   总被引：2，自引：1，他引：1  

C. Derksen  S. L. Smith  M. Sharp  L. Brown  S. Howell  L. Copland  D. R. Mueller  Y. Gauthier  C. G. Fletcher  A. Tivy  M. Bernier  J. Bourgeois  R. Brown  C. R. Burn  C. Duguay  P. Kushner  A. Langlois  A. G. Lewkowicz  A. Royer  A. Walker 《Climatic change》2012,115(1):59-88

During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40?years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure.  相似文献   

Detecting stratigraphical issues using direct radiocarbon dating from small-mammal remains     

Juan Rofes  Sophie Cersoy  Antoine Zazzo  Aurelien Royer  Pierre-Yves Nicod  Veronique Laroulandie  Mathieu Langlais  Yvan Pailler  Celine Leandri  Franck Leandri  Matthieu Lebon  Anne Tresset 《第四纪科学杂志》2020,35(4):505-513

Frequently preserved in archaeological and palaeontological sites, the tiny size of small-mammal remains favours percolations into underlying layers along stratigraphic sequences. This is one of the various post-depositional processes that may affect the integrity of the original deposits and therefore the subsequent scientific interpretations. Recent developments in sample preparation offer the possibility of detecting intrusive episodes through the absolute dating of minute amounts of bone (down to 10 mg), meaning that isolated elements (such as mandibles in this case) are sufficient to obtain reliable radiocarbon dates if collagen is moderately to well preserved. The radiocarbon dates obtained here for small-mammal bones (recovered from pre-Bølling to recent deposits) and their comparison with previous dates obtained from other sources (large-mammal bones, charcoal, botanical samples, etc.), with different protocols and instruments, illustrate the potential of small-mammal dating to reveal (and eventually contribute a solution to) stratigraphical issues in different archaeological contexts.  相似文献   

Erratum to: Climate change under aggressive mitigation: the ENSEMBLES multi-model experiment     

T. C. Johns  J.-F. Royer  I. Höschel  H. Huebener  E. Roeckner  E. Manzini  W. May  J.-L. Dufresne  O. H. Otterå  D. P. van Vuuren  D. Salas y Melia  M. A. Giorgetta  S. Denvil  S. Yang  P. G. Fogli  J. Körper  J. F. Tjiputra  E. Stehfest  C. D. Hewitt 《Climate Dynamics》2011,37(5-6):1269-1270

  相似文献   

The missing Myopus: plugging the gaps in Late Pleistocene small mammal identification in western Europe with geometric morphometrics     

Louis Arbez  Aurelien Royer  Danielle Schreve  Remi Laffont  Serge David  Sophie Montuire 《第四纪科学杂志》2021,36(2):224-238

Lemmus and Myopus are two lemming species with distinct habitat requirements but which show very similar dental morphologies. They are thus extremely difficult to distinguish from one another in the fossil record on the basis of their dental remains, leading to poor understanding of the palaeobiogeographical evolution of Myopus as well as inaccurate palaeoenvrionmental reconstructions. Currently, the presence of Myopus in the fossil register from the Pleistocene is still debated and no firm occurrence of this lemming in western Europe has yet been confirmed for the Late Pleistocene. In this paper, we used geometric morphometrics on modern material to establish morphological differences between Lemmus and Myopus teeth (first lower and third upper molars). Morphological data were then used to build a robust linear discriminant model able to confidently classify isolated teeth of these two genera, and finally, linear discriminant models were used on fossil remains of Lemmus/Myopus from two Late Pleistocene archaeological/palaeontological sites (Grotte des Gorges and Gully Cave). This study demonstrates, for the first time, the presence of Myopus schisticolor in west European Late Pleistocene sites between the end of Marine Isotope Stage 3 and the beginning of the Holocene, during climatic events that favoured the development of taiga forest of birch and pine in these regions.  相似文献   

Regional hydrological cycle changes in response to an ambitious mitigation scenario     

H. Huebener  M. G. Sanderson  I. Höschel  J. Körper  T. C. Johns  J.-F. Royer  E. Roeckner  E. Manzini  J.-L. Dufresne  O. H. Otterå  J. Tjiputra  D. Salas y Melia  M. Giorgetta  S. Denvil  P. G. Fogli 《Climatic change》2013,120(1-2):389-403

Climate change impacts on the regional hydrological cycle are compared for model projections following an ambitious emissions-reduction scenario (E1) and a medium-high emissions scenario with no mitigation policy (A1B). The E1 scenario is designed to limit global annual mean warming to 2 °C or less above pre-industrial levels. A multi-model ensemble consisting of ten coupled atmosphere–ocean general circulation models is analyzed, which includes five Earth System Models containing interactive carbon cycles. The aim of the study is to assess the changes that could be mitigated under the E1 scenario and to identify regions where even small climate change may lead to strong changes in precipitation, cloud cover and evapotranspiration. In these regions the hydrological cycle is considered particularly vulnerable to climate change, highlighting the need for adaptation measures even if strong mitigation of climate change would be achieved. In the A1B projections, there are significant drying trends in sub-tropical regions, precipitation increases in high latitudes and some monsoon regions, as well as changes in cloudiness and evapotranspiration. These signals are reduced in E1 scenario projections. However, even under the E1 scenario, significant precipitation decrease in the subtropics and increase in high latitudes are projected. Particularly the Amazon region shows strong drying tendencies in some models, most probably related to vegetation interaction. Where climate change is relatively small, the E1 scenario tends to keep the average magnitude of potential changes at a level comparable to current intra-seasonal to inter-annual variability at that location. Such regions are mainly located in the mid-latitudes.  相似文献   

Characterization of atmospheric aerosols across Canada from a ground‐based sunphotometer network: AEROCAN     

A.I. Bokoye  A. Royer  N.T. O'Neil  P. Cliche  G. Fedosejevs  P.M. Teillet 《大气与海洋》2013,51(4):429-456

Abstract

Ground‐based sunphotometry measurements acquired under clear sky conditions can be used to investigate atmospheric aerosol optical properties. Such measurements are not only important in their own right as a technique for monitoring generic aerosol dynamics, but also represent a direct means of evaluating the contribution of aerosol induced radiative forcing in the modelling of climate change. In this paper we analyze derived aerosol optical properties using datasets from the Canadian AEROCAN (AERosol CANada) sunphotometer network.

The AEROCAN network currently includes eight sunphotometers distributed across Canada at sites chosen in order to obtain a diverse sampling of continental, maritime and arctic aerosols. Some of these sites have been operational since 1993 as part of the Boreal Ecosystem‐Atmosphere Study (BOREAS). These instruments permit standard and automatic multi‐wavelength measurements of solar extinction radiance centred on the solar disk as well as sky radiance scans off the solar disk. These data yields aerosol optical depth, the Ångström exponent, aerosol particle volume size distribution, refractive index, column‐averaged single scattering albedo, and precipitable water vapour content.

Spatial and temporal trends of these parameters as well as observed inter‐correlations are discussed. The results demonstrate the utility and significance of these types of measurements and illustrate the potential applications of networked sunphotometry data.  相似文献   

Analyse régionale des simulations climatiques du modèle canadien de circulation générale de l'atmosphère pour le territoire québécois     

Alain A. Viau  Alain Royer  Colette Ansseau  Jean Boivin 《大气与海洋》2013,51(3):389-402

Abstract

Current understanding of the possible nature of climatic change at the regional scale is limited by the spatial resolution of General Circulation Models (GCM). The use of GCM outputs without correction linked to the spatial variability of the variables can bring significant errors in their utilization at the regional scale. The potential of the Canadian GCM for regional applications in Quebec has been analysed by comparison to the climatic normals of temperature and precipitation, measured over the Quebec climatological network, on an annual and seasonal basis. This analysis has been undertaken with the support of a geographical information system (GIS) (PAMAP). In summary, a difference between the climatic normal and the GCM output has been estimated at 20% for temperature and 30% for precipitation. We present an analysis of a corrected regionalized scenario for the province of Quebec of the possible climatic change simulated by the Canadian GCM under the hypothesis of a doubling of atmospheric CO₂. Results show an increase of the annual average temperature of 4° C for summer and 6°C for winter, associated with an average increase of 80 mm (10%) in annual precipitation, reaching 25% in some regions.  相似文献