检索结果-南通市图书馆

The Relationship between Nonconservative Schemes and Initial Values of Nonlinear Evolution Equations

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2004年第2期21卷 277-282页

作者：林万涛 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

For the nonconservative schemes of the nonlinear evolution equations, taking the one-dimensional shallow water wave equation as an example, the necessary conditions of computational stability are given. Based on numerical tests, the relationship between the nonlinear computational stability and the construction of difference schemes, as well as the form of initial values, is further discussed. It is proved through both theoretical analysis and numerical tests that if the construction of difference schemes is definite, the computational stability of nonconservative schemes is decided by the form of initial values.

关键词： nonlinear evolution equation nonconservative scheme initial value

Warming in the Northwestern Indian Ocean Associated with the El Nio Event

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2008年第2期25卷 246-252页

作者：袁媛周文杨辉李崇银 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Department of Physics and Materials Science. City University of Hong Kong State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences

This paper investigates possible warming effects of an E1 Nifio event on the sea surface temperature anomaly （SSTA） in the northwestern Indian Ocean. Most pure positive Indian Ocean dipole （IOD） events （without an E1 Nifio event co-occurring） have a maximum positive SSTA mainly in the central Indian Ocean south of the equator, while most co-occurrences with an E1 Nifio event exhibit a northwest-southeast typical dipole mode. It is therefore inferred that warming in the northwestern Indian Ocean is closely related to the E1 Nifio event. Based on the atmospheric bridge theory, warming in the northwestern Indian Ocean during co-occurring cases may be primarily caused by relatively less latent heat loss from the ocean due to reduced wind speed. The deepened thermocline also contributes to the warming along the east coast of Africa through the suppressed upwelling of the cold water. Therefore, the E1 Nifio event is suggested to have a modulating effect on the structure of the dipole mode in the tropical Indian Ocean.

关键词： positive Indian Ocean dipole E1 Nifio latent heat flux thermocline

Dynamic Features and Maintenance Mechanism of Asian Summer Monsoon Subsystem

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 1999年第4期16卷 523-536页

作者：徐建军吴国雄 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics ( LASG) Institute of Atmspheric Physics Chinese Academy of Sciences Beijing

In the context of the dissociation of vertical shear flow and tropospheric mean flow based on 1980-1996 NCEP/ NCAR re-analysis, study is undertaken of the barotropic and baroclinic development characteristics and kinetic energy maintenance mechanisms of Asian summer monsoon. Evidence suggests that the monsoon activity is marked by noticeable baroclinicity in three active regions of different dynamical characteristics, located in India, East Asian tropics and subtropics, respectively, with greatly differing maintenance mechanisms of barotropic / baroclinic kinetic energy.

关键词： Monsoon Barotropic Baroclinic Maintenance

Coupled Model Simulations of Climate Changes in the 20th Century and Beyond

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2008年第4期25卷 641-654页

作者：俞永强智海王斌万慧李超刘海龙李薇郑伟鹏周天军 State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics(LASG) Institute of Atmospheric Physics(IAP)Chinese Academy of Sciences

Several scenario experiments of the IPCC 4th Assessment Report （AR4） are performed by version g1.0 of a Flexible coupled Ocean-Atmosphere-Land System Model （FGOALS） developed at the Institute of Atmospheric Physics, Chinese Academy of Sciences （IAP/CAS）, including the ＂Climate of the 20th century experiment＂, ＂CO2 1% increase per year to doubling experiment＂ and two separate IPCC greenhouse gases emission scenarios AIB and B1 experiments. To distinguish between the different impacts of natural variations and human activities on the climate change, three-member ensemble runs are performed for each scenario experiment. The coupled model simulations show：（1） from 1900 to 2000, the global mean temper- ature increases about 0.5℃ and the major increase occurs during the later half of the 20th century, which is in consistent with the observations that highlights the coupled model＇s ability to reproduce the climate changes since the industrial revolution; （2） the global mean surface air temperature increases about 1.6℃ in the CO2 doubling experiment and 1.5℃ and 2.4℃ in the A1B and B1 scenarios, respectively. The global warming is indicated by not only the changes of the surface temperature and precipitation but also the temperature increase in the deep ocean. The thermal expansion of the sea water would induce the rise of the global mean sea level. Both the control run and the 20th century climate change run are carried out again with version g1.1 of FGOALS, in which the cold biases in the high latitudes were removed. They are then compared with those from version g1.0 of FGOALS in order to distinguish the effect of the model biases on the simulation of global warming.

关键词： greenhouse effect coupled GCM human activity

Numerical Simulation of Global Temperature Change during the 20th Century with the IAP/LASG GOALS Model

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2004年第2期21卷 227-235页

作者：马晓燕郭裕福石广玉俞永强 State Key laboratory of Numerical Modeling for Atmospherics Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

The IAP/LASG GOALS coupled model is used to simulate the climate change during the 20th century using historical greenhouse gases concentrations, the mass mixing ratio of sulfate aerosols simulated by a CTM model, and reconstruction of solar variability spanning the period 1900 to 1997. Four simulations, including a control simulation and three forcing simulations, are conducted. Comparison with the observational record for the period indicates that the three forcing experiments simulate reasonable temporal and spatial distributions of the temperature change. The global warming during the 20th century is caused mainly by increasing greenhouse gas concentration especially since the late 1980s; sulfate aerosols offset a portion of the global warming and the reduction of global temperature is up to about 0.11℃ over the century; additionally, the effect of solar variability is not negligible in the simulation of climate change over the 20th century.

关键词： global warming greenhouse gases sulfate aerosols solar variability

Impacts of Multi-Scale Solar Activity on *** Ⅱ:Dominant Timescales in Decadal-Centennial Climate Variability

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2012年第4期29卷 887-908页

作者： Hengyi WENG State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

Part II of this study detects the dominant decadal-centennial timescales in four SST indices up to the 2010/2011 winter and tries to relate them to the observed 11-yr and 88-yr solar activity with the sunspot number up to Solar Cycle 24. To explore plausible solar origins of the observed decadal-centennial timescales in the SSTs and climate variability in general, we design a simple one-dimensional dynamical system forced by an annual cycle modulated by a small-amplitude single- or multi-scale ＂solar activity.＂ Results suggest that nonlinear harmonic and subharmonic resonance of the system to the forcing and period-doubling bifurcations are responsible for the dominant timescales in the system, including the 60-yr timescale that dominates the Atlantic Multidecadal Oscillation. The dominant timescales in the forced system depend on the system＇s parameter setting. Scale enhancement among the dominant response timescales may result in dramatic amplifications over a few decades and extreme values of the time series on various timescales. Three possible energy sources for such amplifications and extremes are proposed. Dynamical model results suggest that solar activity may play an important yet not well recognized role in the observed decadal-centennial climate variability. The atmospheric dynamical amplifying mechanism shown in Part I and the nonlinear resonant and bifurcation mechanisms shown in Part II help us to understand the solar source of the multi-scale climate change in the 20th century and the fact that different solar influenced dominant timescales for recurrent climate extremes for a given region or a parameter setting. Part II also indicates that solar influences on climate cannot be linearly compared with non-cyclic or sporadic thermal forcings because they cannot exert their influences on climate in the same way as the sun does.

关键词： sun-climate relationship decadal-centennial climate timescales nonlinear forcing-response res- onant mechanism bifurcation mechanism scale enhancement for extremes

Effect of the Lower Boundary Position of the Fourier Equation on the Soil Energy Balance

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2004年第6期21卷 868-878页

作者：孙菽芬张霞 State Key laboratory of Numerical Modeling for Atmospherics Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

In this study, the e?ect of the lower boundary position selection for the Fourier equation on heat transfer and energy balance in soil is evaluated. A detailed numerical study shows that the proper position of the lower boundary is critical when solving the Fourier equation by using zero heat ?ux as the lower boundary condition. Since the position de?nes the capacity of soil as a heat sink or source, which absorbs and stores radiation energy from the sky in summer and then releases the energy to the atmosphere in winter, and regulates the deep soil temperature distribution, the depth of the position greatly in?uences the heat balance within the soil as well as the interaction between the soil and the atmosphere. Based on physical reasoning and the results of numerical simulation, the proper depth of the position should be equal to approximately 3 times of the annual heat wave damping depth. For most soils, the proper lower boundary depth for the Fourier equation should be around 8 m to 15 m, depending on soil texture.

关键词： thermal conductivity lower boundary position effect on heat balance

Impacts of Multi-Scale Solar Activity on *** Ⅰ:Atmospheric Circulation Patterns and Climate Extremes

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2012年第4期29卷 867-886页

作者： Hengyi WENG State Key laboratory of Numerical Modeling for Atmospheric Sciences and geophysical fluid dynamics Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029

The impacts of solar activity on climate are explored in this two-part study. Based on the principles of atmospheric dynamics, Part I propose an amplifying mechanism of solar impacts on winter climate extremes through changing the atmospheric circulation patterns. This mechanism is supported by data analysis of the sunspot number up to the predicted Solar Cycle 24, the historical surface temperature data, and atmospheric variables of NCEP/NCAR Reanalysis up to the February 2011 for the Northern Hemisphere winters. For low solar activity, the thermal contrast between the low- and high-latitudes is enhanced, so as the mid-latitude baroclinic ultra-long wave activity. The land-ocean thermal contrast is also enhanced, which amplifies the topographic waves. The enhanced mid-latitude waves in turn enhance the meridional heat transport from the low to high latitudes, making the atmospheric ＂heat engine＂ more efficient than normal. The jets shift southward and the polar vortex is weakened. The Northern Annular Mode （NAM） index tends to be negative. The mid-latitude surface exhibits large-scale convergence and updrafts, which favor extreme weather/climate events to occur. The thermally driven Siberian high is enhanced, which enhances the East Asian winter monsoon （EAWM）. For high solar activity, the mid-latitude circulation patterns are less wavy with less meridional transport. The NAM tends to be positive, and the Siberian high and the EAWM tend to be weaker than normal. Thus the extreme weather/climate events for high solar activity occur in different regions with different severity from those for low solar activity. The solar influence on the mid- to high-latitude surface temperature and circulations can stand out after removing the influence from the E1 Nifio-Southern Oscillation. The atmospheric amplifying mechanism indicates that the solar impacts on climate should not be simply estimated by the magnitude of the change in the solar radiation over solar cycles when it i

关键词： solar impacts on climate surface thermal contrasts dynamical amplifying mechanism atmo- spheric circulations climate extremes

Study on Atmospheric Travelling Wave Solutions and Review of Its Present Developments

在线全文

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 1993年第4期10卷 435-446页

作者：黄思训张铭 laboratory of Numerical Modelling for Atmospheric Sciences and geophysical fluid dynamics Chinese Academy of Sciences Beijing 100080

The scientific achievements of travelling waves in a barotropic atmosphere are introduced, including i) the existence conditions of periodic solutions (wavetrain solutions) and solitary wave solutions (pulse solutions), together with the solution finding methods and a series of related problems, ii) seeking solutions of monotonous wave (wave front) and of nonmonotonous travelling wave (oscillatory wave) by using phase plane shooting technique and hi) progress in the study of travelling wave solution at home and abroad. The investigation of travelling wave solutions in recent years has been found in mathematics, physics, chemistry, biology and other sciences. Over the past decade the problem has been the subject of much interest and become an important area of research. So it is no doubt of great significance to investigate the travelling wave solutions and thereby explain phenomena of weather.

关键词： Barotropic atmosphere Wavetrain Wave front Travelling wave solution (TWS) Pulse solution Nonmonotonous travelling wave solution