A PRELIMINARY VALIDATION STUDY OF THE SEASONAL FORECAST OF CCCMA MODEL OVER CHINA          下载免费PDF全文

DONG Min  Francis ZWIERS  YE Zhengqing 《Acta Meteorologica Sinica》2000,14(3):268-279

In this study we validate the raw ensemble mean forecasts of the CCCma's GCM2 modelagainst surface temperature and precipitation data obtained from 160 Chinese stations.It is foundthat despite the lagre biases,the model was able to produce seasonal anomalies that haveproperties that are reasonably close to those that are observed.This anomaly is the quantity ofinterest when forecasting seasonal climatic conditions.The root mean squared difference(RMSD)between the forecast and observed anomaly leads us to be modestly optimistic about the prospectsfor using dynamical models to forecast the interannual variability of some meteorological elements.The correlation analysis of the forecast and observation also supports the result given by theRMSD analysis and provides a tool for identify the forecast confidence level in various regions,  相似文献   

Dives into outer Coronado Canyon System     

Francis P. Shepard  Neil F. Marshall 《Marine Geology》1975,18(5):313-323

Dives in Lockheed's submarine “Deep Quest” followed the floor of the fan valley and outer gorge of Coronado Canyon, southwest of the California—Baja California border. Both the fan valley and outer gorge have meandering courses. Basin depressions and intermittent steep descents characterize the outer gorge. No indications were found of recent activity of turbidity currents at either location, but a sand layer 30 cm below the surface is interpreted as related to a lower stand of sea level at the close of the last ice age. Abundant organisms were seen on the valley floor and in the overlying water.  相似文献   

Introduction     

Francis Owusu 《GeoJournal》2005,62(1):115-116

  相似文献   

Ferric iron in mantle-derived garnets   总被引：4，自引：0，他引：4  

Robert W. Luth  David Virgo  Francis R. Boyd  Bernard J. Wood 《Contributions to Mineralogy and Petrology》1990,104(1):56-72

The oxidation state of a mantle assemblage may be defined by heterogeneous reactions between oxygen and iron-bearing minerals. In spinel lherzolites, the presence of Fe³⁺ in spinel allows use of the assemblage olivine-orthopyroxene-spinel to define f _{O 2} at fixed T and P. As a first step towards establishing an analogous reaction for garnet lherzolites, garnets from mantle-derived xenoliths from South Africa and the USSR have been analyzed with ⁵⁷Fe Mössbauer spectroscopy at 298 and 77K to determine Fe³⁺/Fe²⁺ and the coordination state of iron. Garnets from South African alkremites (pyrope+Mg-spinel) and eclogites, as well as garnet-spinel and low-temperature garnet lherzolites from both South Afica and the USSR, have Fe³⁺/Fe<0.07. In contrast, garnets from high-temperature garnet lherzolites from within the Kaapvaal craton of South Africa have Fe³⁺/Fe>0.10. Ferric iron is octahedrally coordinated, and ferrous iron is present in the dodecahedral site in all samples. The occurrence of significant Fe³⁺ in these garnets necessitates caution in the use of geothermometers and geobarometers that are applied to mantle samples. For example, the presence of 12% of the Fe as Fe³⁺ in garnets can increase temperatures calculated from existing Fe/Mg geothermometers by>200°C. The concomitant increase in pressures calculated from geobarometers that use the Al content in orthopyroxene coexisting with garnet are 10–15 kbar. Results of calculations based on heterogeneous equilibria between garnet, olivine, and pyroxene are consistent with the derivation of the peridotite samples from source regions that are relatively oxidized, between the f _{O 2} of the FMQ (quartz-fayalite-magnetite) buffer and that of the WM buffer. No samples yield values of f _{O 2} as reduced as IW (iron-wüstite buffer).  相似文献   

Analysis of coupled Sr/Ca and Sr/Sr variations in enamel using laser-ablation tandem quadrupole-multicollector ICPMS     

Vincent Balter  Philippe Telouk  José Braga  Francis Albarède 《Geochimica et cosmochimica acta》2008,72(16):3980-3990

We present in this study results obtained with a laser-ablation coupled with both a quadrupole and a multi-collector ICPMS. The simultaneous in situ Sr/Ca and ⁸⁷Sr/⁸⁶Sr measurements along growth profiles in enamel allows the concomitant diet and migration patterns in mammals to be reconstructed. Aliquots of the powdered international standard NIST “SRM1400 Bone Ash” with certified Sr and Ca contents, was sintered at high pressure and temperature and was adopted as the reference material for external reproducibility and calibration of the results. A total of 145 coupled elemental and isotopic measurements of herbivores enamel from the Kruger National Park, South Africa, gives intra-tooth Sr/Ca and ⁸⁷Sr/⁸⁶Sr variations that are well larger than external reproducibility. Sr/Ca profiles systematically decrease from the dentine-enamel junction to the outer enamel whereas ⁸⁷Sr/⁸⁶Sr profiles exhibit variable patterns. Using a simple geometric model of hypsodont teeth growth, we demonstrate that a continuous recording of the ⁸⁷Sr/⁸⁶Sr variations can be reconstructed in the tooth length axis. This suggests that the mobility of a mammal can be reconstructed over a period of more than a year with a resolution of a ten of days, by sampling enamel along growth profiles. Our geometric model of hypsodont teeth growth predicts that an optimal distance between two successive profiles is equal to the enamel thickness. However, this model does not apply to the Sr/Ca signal which is likely to be altered during the enamel maturation stage due to differential maturation processes along enamel thickness. Here, the observed constant decreases of the Sr/Ca ratios in the ungulates of Kruger National Park suggests that they did not changed of diet, while some of them were migrating.  相似文献   

Optimum data weighting and error calibration for estimation of gravitational parameters   总被引：1，自引：0，他引：1  

Francis J. Lerch 《Journal of Geodesy》1991,65(1):44-52

Summary A new approach has been developed for determining consistent satellite-tracking data weights in solutions for the satellite-only gravitational models. The method employs subset least-squares solutions of the satellite data contained within the complete solution and requires that the differences of the parameters of subset solutions and the complete solution to be in agreement with their error estimates by adjusting the data weights. GEM-T2 model was recently computed and adjusted through a direct application of this method. The estimated data weights are markedly smaller than the weights implied by the formal uncertainties of the measurements. Orbital arc tests as well as surface gravity comparisons show significant improvements for solutions when more realistic data weighting is achieved.  相似文献   

Gold '89 in Europe     

Francis Saupé  Francis Tollon 《Mineralium Deposita》1990,25(1):S1-S2

  相似文献   

Groundwater quality assessment using statistical approach and water quality index in Ejisu-Juaben Municipality,Ghana     

Thomas Kwame Boateng  Francis Opoku  Samuel Osafo Acquaah  Osei Akoto 《Environmental Earth Sciences》2016,75(6):489

  相似文献   

Evaluation of extreme rainfall and temperature over North America in CanRCM4 and CRCM5     

Kirien Whan  Francis Zwiers 《Climate Dynamics》2016,46(11-12):3821-3843

  相似文献   

Modeling environmental effects on the size-structured energy flow through marine ecosystems. Part 2: Simulations     

Olivier Maury  Yunne-Jai Shin  Blaise Faugeras  Tamara Ben Ari  Francis Marsac 《Progress in Oceanography》2007,74(4):500-514

Numerical simulations using a physiologically-based model of marine ecosystem size spectrum are conducted to study the influence of primary production and temperature on energy flux through marine ecosystems. In stable environmental conditions, the model converges toward a stationary linear log–log size-spectrum. In very productive ecosystems, the model predicts that small size classes are depleted by predation, leading to a curved size-spectrum.It is shown that the absolute level of primary production does not affect the slope of the stationary size-spectrum but has a nonlinear effect on its intercept and hence on the total biomass of consumer organisms (the carrying capacity). Three domains are distinguished: at low primary production, total biomass is independent from production changes because loss processes dominate dissipative processes (biological work); at high production, ecosystem biomass is proportional to primary production because dissipation dominates losses; an intermediate transition domain characterizes mid-production ecosystems. Our results enlighten the paradox of the very high ecosystem biomass/primary production ratios which are observed in poor oceanic regions. Thus, maximal dissipation (least action and low ecosystem biomass/primary production ratios) is reached at high primary production levels when the ecosystem is efficient in transferring energy from small sizes to large sizes. Conversely, least dissipation (most action and high ecosystem biomass/primary production ratios) characterizes the simulated ecosystem at low primary production levels when it is not efficient in dissipating energy.Increasing temperature causes enhanced predation mortality and decreases the intercept of the stationary size spectrum, i.e., the total ecosystem biomass. Total biomass varies as the inverse of the Arrhenius coefficient in the loss domain. This approximation is no longer true in the dissipation domain where nonlinear dissipation processes dominate over linear loss processes. Our results suggest that in a global warming context, at constant primary production, a 2–4 °C warming would lead to a 20–43% decrease of ecosystem biomass in oligotrophic regions and to a 15–32% decrease of biomass in eutrophic regions.Oscillations of primary production or temperature induce waves which propagate along the size-spectrum and which amplify until a “resonant range” which depends on the period of the environmental oscillations. Small organisms oscillate in phase with producers and are bottom-up controlled by primary production oscillations. In the “resonant range”, prey and predators oscillate out of phase with alternating periods of top-down and bottom-up controls. Large organisms are not influenced by bottom-up effects of high frequency phytoplankton variability or by oscillations of temperature.  相似文献