CO2增加引起的温室效应对我国沿海台风影响的数值模拟试验     

高学杰  林一骅  赵宗慈  Filippo Giorgi 《热带海洋学报》2003,22(4):77-83

使用RegCM2区域气候模式单向嵌套澳大利亚CSIRO R21L9全球海—气耦合模式，进行了CO2加倍情况下影响中国的台风变化的数值试验研究。首先分析了区域模式对中国气候的模拟能力，结果表明，区域模式由于具有较高的分辨率，因而对中国区域地面气温和降水的模拟效果较全球模式有了较大提高。随后就温室效应对台风的影响情况进行了分析，发现计算区域内台风生成的个数将有一定增加，而登陆我国的台风数目会有明显增加；同时台风的路径将以由南向北移动，在华南登陆影响我国的方式为主。  相似文献   

The effect of sewage discharge on the ecosystem engineering activities of two East African fiddler crab species: consequences for mangrove ecosystem functioning   总被引：1，自引：0，他引：1  

Bartolini F  Cimò F  Fusi M  Dahdouh-Guebas F  Lopes GP  Cannicci S 《Marine environmental research》2011,71(1):53-61

A number of studies have suggested that mangrove forests and their faunal components may be pre-adapted to the impact of organic waste discharge, making them possible natural wastewater treatment wetlands. However, the results from recent research are contradictory. Some studies have shown that negative effects, sometimes subtle and difficult to observe, can be detected on specific biotic components of forests subjected to organic pollution. Therefore, the aim of the present study was to investigate possible alterations in the ecosystem engineering activities of a fiddler crab community dominating the landward belts of Kenyan mangrove forests. The total processed sediment produced by burrowing and foraging activities in a population from a peri-urban mangrove area receiving untreated domestic sewage was compared with that from a forest not affected by urban wastewater. The results showed how the peri-urban site hosted a higher biomass of crabs, which produced a significantly lower amount of processed sediment compared with the pristine site, resulting in a lower total top sediment mixing activity of the crabs. Thus, the present study showed a link between sewage exposure and top sediment reworking by crabs, which is potentially beneficial for mangrove growth and ecosystem functioning. This represents a possible example of cryptic ecological degradation in mangal systems.  相似文献   

A multimodel intercomparison of resolution effects on precipitation: simulations and theory     

Sara A. Rauscher  Travis A. O’Brien  Claudio Piani  Erika Coppola  Filippo Giorgi  William D. Collins  Patricia M. Lawston 《Climate Dynamics》2016,47(7-8):2205-2218

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Experimental Assessment of the Stress–Strain Behaviour of Leighton Buzzard Sand for the Calibration of a Constitutive Model     

Giovanni Lanzano  Ciro Visone  Emilio Bilotta  Filippo Santucci de Magistris 《Geotechnical and Geological Engineering》2016,34(4):991-1012

A number of constitutive models are nowadays implemented in numerical codes which simulate the stress–strain behaviour of soil from very small to large strain. In this paper, the mechanical behaviour of Leighton Buzzard sand (grade E), used worldwide for physical modelling, has been thoroughly characterized by laboratory testing along several stress paths. Tests were aimed at calibrating a constitutive model, that allows considering stiffness nonlinearities in a wide range of strains, in the framework of isotropically hardening plasticity. As a validation, the results of dynamic centrifuge tests on a layer of the same sand were compared with finite element predictions.  相似文献   

Some limitations in using <Superscript>222</Superscript>Rn to assess river–groundwater interactions: the case of Castel di Sangro alluvial plain (central Italy)     

Luisa Stellato  Emma Petrella  Filippo Terrasi  Paolo Belloni  Maria Belli  Umberto Sansone  Fulvio Celico 《Hydrogeology Journal》2008,16(4):701-712

²²²Rn was used to assess river–groundwater interactions within Castel di Sangro alluvial aquifer (Italy). The effectiveness of results obtained through this indicator was verified by also analyzing δ¹⁸O, major ions and temperature in both surface and groundwater, and carrying out piezometric head monitoring and discharge measurements. Hydrogeological investigations suggested that the river infiltrates into the aquifer in the south-eastern aquifer portion, while groundwater discharges into the river in the north-eastern portion. The latter phenomenon is supported by ²²²Rn data. Nevertheless, flow-through conditions cause the modelled discharge along this river reach, estimated by ²²²Rn data in a degassing-corrected two-component mixing model, to be greater than the measured discharge. Concerning river infiltration into the aquifer, δ¹⁸O, major ions and temperature data show that the river contribution is negligible in terms of aquifer recharge. Thus, the observed increase in ²²²Rn concentration in that portion of the aquifer is due to the enrichment process caused by infiltration of rainwater (²²²Rn free) which flows from the local divide area. Hence, in the study site, the use of only ²²²Rn to predict river–groundwater interactions causes some estimation inaccuracies and it must be coupled with other hydrochemical and hydrogeological parameters to gain a thorough understanding of such interactions.  相似文献   

Cold gas accretion in galaxies     

Renzo Sancisi  Filippo Fraternali  Tom Oosterloo  Thijs van der Hulst 《Astronomy and Astrophysics Review》2008,15(3):189-223

Evidence for the accretion of cold gas in galaxies has been rapidly accumulating in the past years. HI observations of galaxies and their environment have brought to light new facts and phenomena which are evidence of ongoing or recent accretion: (1) A large number of galaxies are accompanied by gas-rich dwarfs or are surrounded by HI cloud complexes, tails and filaments. This suggests ongoing minor mergers and recent arrival of external gas. It may be regarded, therefore, as direct evidence of cold gas accretion in the local universe. It is probably the same kind of phenomenon of material infall as the stellar streams observed in the halos of our galaxy and M 31. (2) Considerable amounts of extra-planar HI have been found in nearby spiral galaxies. While a large fraction of this gas is undoubtedly produced by galactic fountains, it is likely that a part of it is of extragalactic origin. Also the Milky Way has extra-planar gas complexes: the Intermediate- and High-Velocity Clouds (IVCs and HVCs). (3) Spirals are known to have extended and warped outer layers of HI. It is not clear how these have formed, and how and for how long the warps can be sustained. Gas infall has been proposed as the origin. (4) The majority of galactic disks are lopsided in their morphology as well as in their kinematics. Also here recent accretion has been advocated as a possible cause. In our view, accretion takes place both through the arrival and merging of gas-rich satellites and through gas infall from the intergalactic medium (IGM). The new gas could be added to the halo or be deposited in the outer parts of galaxies and form reservoirs for replenishing the inner parts and feeding star formation. The infall may have observable effects on the disk such as bursts of star formation and lopsidedness. We infer a mean “visible” accretion rate of cold gas in galaxies of at least . In order to reach the accretion rates needed to sustain the observed star formation (), additional infall of large amounts of gas from the IGM seems to be required.  相似文献   

A daily temperature dataset over China and its application in validating a RCM simulation   总被引：36，自引：0，他引：36  

徐影  高学杰  沈艳  许崇海  石英 《大气科学进展》2009,26(4):763-772

This paper describes the construction of a 0.5°×0.5°daily temperature dataset for the period of 1961- 2005 over mainland China for the purpose of climate model validation. The dataset is based on the in- terpolation from 751 observing stations in China and comprises 3 variables: daily mean,minimum,and maximum temperature.The"anomaly approach"is applied in the interpolation.The gridded climatology of 1971-2000 is first calculated and then a gridded daily anomaly for 1961-2005 is added to the climatologY to o...  相似文献   

Present climate simulation over Korea with a regional climate model using a one-way double-nested system   总被引：1，自引：0，他引：1  

E.-S. Im  E.-H. Park  W.-T. Kwon  F. Giorgi 《Theoretical and Applied Climatology》2006,86(1-4):187-200

Summary This study investigates the capability of the regional climate model RegCM3 to simulate surface air temperature and precipitation over the Korean Peninsula. The model is run in one-way double nested mode, with a 60 km grid point spacing “mother” domain encompassing the eastern regions of Asia and a 20 km grid point spacing nested domain covering the Korean Peninsula. The simulation spans the three-year period of 1 October 2000 through 30 September 2003 and the boundary conditions needed to run the mother domain experiment are provided from the NCEP reanalysis of observations. The model results are compared with a high density station observation dataset to examine the fine scale structure of the surface climate signal. The model shows a good performance in capturing both the sign and magnitude of the seasonal and inter-annual variations of the surface variables both over East Asia as a whole and over the Korean Peninsula in the nested system. Some persistent biases are however present. Surface temperature is systematically underestimated, especially over mountainous regions in the warm season. This feature may be due to the relatively coarse representation of the Korean topography. The simulated precipitation over the mother domain successfully reproduces the broad spatial pattern of observed precipitation over East Asia along with its seasonal evolution. On the other hand, fine scale details from the nested results show a varying level of quality for the different individual years. Because of the better resolved topographic forcing, the increased resolution of the nested model improves the spatial agreement with the fine scale observation fields for temperature and cold season precipitation. For summer monsoon precipitation the simulation of individual monsoon convective events and tropical storms is however more important than the topographic forcing, and therefore the performance of the nested system is more case-dependent.  相似文献   

Comparison of regional climate model and statistical downscaling simulations of different winter precipitation change scenarios over Romania     

A. Busuioc  F. Giorgi  X. Bi  M. Ionita 《Theoretical and Applied Climatology》2006,86(1-4):101-123

Summary Regional climate model and statistical downscaling procedures are used to generate winter precipitation changes over Romania for the period 2071–2100 (compared to 1961–1990), under the IPCC A2 and B2 emission scenarios. For this purpose, the ICTP regional climate model RegCM is nested within the Hadley Centre global atmospheric model HadAM3H. The statistical downscaling method is based on the use of canonical correlation analysis (CCA) to construct climate change scenarios for winter precipitation over Romania from two predictors, sea level pressure and specific humidity (either used individually or together). A technique to select the most skillful model separately for each station is proposed to optimise the statistical downscaling signal. Climate fields from the A2 and B2 scenario simulations with the HadAM3H and RegCM models are used as input to the statistical downscaling model. First, the capability of the climate models to reproduce the observed link between winter precipitation over Romania and atmospheric circulation at the European scale is analysed, showing that the RegCM is more accurate than HadAM3H in the simulation of Romanian precipitation variability and its connection with large-scale circulations. Both models overestimate winter precipitation in the eastern regions of Romania due to an overestimation of the intensity and frequency of cyclonic systems over Europe. Climate changes derived directly from the RegCM and HadAM3H show an increase of precipitation during the 2071–2100 period compared to 1961–1990, especially over northwest and northeast Romania. Similar climate change patterns are obtained through the statistical downscaling method when the technique of optimum model selected separately for each station is used. This adds confidence to the simulated climate change signal over this region. The uncertainty of results is higher for the eastern and southeastern regions of Romania due to the lower HadAM3H and RegCM performance in simulating winter precipitation variability there as well as the reduced skill of the statistical downscaling model.  相似文献   

Validation of precipitation events in a regional climate model simulation using methods from complex systems theory     

V. Pelino  A. Matera  T. Colombo  F. Giorgi 《Theoretical and Applied Climatology》2006,84(4):213-218

Summary We show that daily precipitation is characterized by a behaviour regulated by power laws. Both for the frequency distribution of both event intensity and drought duration. In this respect, precipitation appears to follow self-organized criticality laws, much as other geophysical phenomena such as avalanches and earthquakes. We use this feature to validate the simulation of daily precipitation events in a multi-decadal regional climate model experiment for the European region. Our focus is on the Italian peninsula and we show that both the model results and the station observations for daily precipitation intensity and drought length follow power laws with comparable values of the relevant parameters. We suggest that complex systems theory can provide useful tools for the validation of precipitation statistics in climate models.  相似文献