As a western boundary current, the Kuroshio is closely related to the large scale oceanic circulation and at the same time, is greatly influenced by the local topography because of its narrow width. Numerical studies ...As a western boundary current, the Kuroshio is closely related to the large scale oceanic circulation and at the same time, is greatly influenced by the local topography because of its narrow width. Numerical studies of the Kuroshio are usually confined to portions of it in different geographical regions since the computer execution time required to run a numerical model of the Pacific using a sufficiently fine grid to resolve adequately the flow structure of the Kuroshio is enormous. In order to circumvent the problems of multiple spatial scales and consistent boundary conditions, nested models are employed in which a coarse grid model of the Pacific is used to supply the open boundary conditions for a finer grid model of the northwestern Pacific to simulate the flow and temperature fields of the Kuroshio in summer and winter. The major features of the Kuroshio have in general been successfully simulated by the nested models.展开更多
This paper presents a numerical study on the 1998 summer rainfall over the Yangtze River valley in central and eastern China, addressing effect of a nested area size on simulations in terms of the technique of nesting...This paper presents a numerical study on the 1998 summer rainfall over the Yangtze River valley in central and eastern China, addressing effect of a nested area size on simulations in terms of the technique of nesting a regional climate model (RCM) upon a general circulation model (GCM). Evidence suggests that the size exerts greater impacts upon regional climate of the country, revealing that a larger nested size is superior to a small one for simulation in mitigating errors of GCM-provided lateral boundary forcing. Also, simulations show that the RCM should incorporate regions of climate systems of great importance into study and a low-resolution GCM yields more pronounced errors as a rule when used in the research of the Tibetan Plateau, and, in contrast, our PσRCM can do a good job in describing the plateau’s role in a more realistic and accurate way. It is for this reason that the tableland should be included in the nested area when the RCM is employed to investigate the regional climate. Our PσRCM nesting upon a GCM reaches more realistic results compared to a single GCM used.展开更多
Grey heron (Ardea cimerca) is one kind of the great birds which are often seen in the northeast marsh area of P.R.China, and there are many grey herons to reproduce in Zhalong Nature Reserve from March to August annua...Grey heron (Ardea cimerca) is one kind of the great birds which are often seen in the northeast marsh area of P.R.China, and there are many grey herons to reproduce in Zhalong Nature Reserve from March to August annually. In this paper, through the inveingation of the grey herons nesting habitat and according to the water depth, vegetation type, cover density and plan heigh of the nesting place, the grey heron’s nesting habitat suitability index medes are established. The main model is s=(s1xs2xs3xs4)1/4,where s1 is the water depth suitability index, s2 is the vegetation type suitability index, s3 is the cover density index, sa is the plant height suitability index. These models provide a kind of reliable method for evaluating the habitat quality of the grey heron’s nesting.展开更多
Today, the nested model is used widely. The effect and role of each nested variate is analyzed in this paper. It is found that the forecast could benefit by nesting part of the variates and the effect of each of the v...Today, the nested model is used widely. The effect and role of each nested variate is analyzed in this paper. It is found that the forecast could benefit by nesting part of the variates and the effect of each of the variates may be different. Therefore, only the effectual variates are chosen for the nesting. According to this finding, a scheme is suggested and applied to the limited area mode (TL10) nested with global spectral mode (T63) for forecasting tropical cyclones over the South China Sea. A few numerical prediction tests show that this scheme is reasonable and efficient.展开更多
A bogus typhoon scheme,designed for the initialization of a typhoon track prediction model,is developed in thispaper.This scheme includes both effects of axisymmetric wind and asymmetric wind.Experimental forecasts us...A bogus typhoon scheme,designed for the initialization of a typhoon track prediction model,is developed in thispaper.This scheme includes both effects of axisymmetric wind and asymmetric wind.Experimental forecasts using atwo-way interactive movable nested mesh model show that the forecast skill of typhoon tracks has clearly improvedafter introducing the bogus typhoon into the initial fields.展开更多
An atmosphere-vegetation interaction model (AVIM) has been coupled with a nine-layer General Cir culation Model (GCM) of Institute of Atmospheic Physics / State Key Laboratory of Numerical Modeling for Atmospheric Sci...An atmosphere-vegetation interaction model (AVIM) has been coupled with a nine-layer General Cir culation Model (GCM) of Institute of Atmospheic Physics / State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (IAP/ LASG), which is rhomboidally truncated at zonal wave number 15, to simulate global climatic mean states. AVIM is a model having inter-feedback between land surface processes and eco-physiological processes on land. As the first step to couple land with atmosphere completely, the physiological processes are fixed and only the physical part (generally named the SVAT (soil-vegetation-atmosphere-transfer scheme) model) of AVIM is nested into IAP/ LASG L9R15 GCM. The ocean part of GCM is prescribed and its monthly sea surface temperature (SST) is the climatic mean value. With respect to the low resolution of GCM, i.e., each grid cell having lon gitude 7.5?and latitude 4.5? the vegetation is given a high resolution of 1.5?by 1.5?to nest and couple the fine grid cells of land with the coarse grid cells of atmosphere. The coupling model has been integrated for 15 years and its last ten-year mean of outputs was chosen for analysis.Compared with observed data and NCEP reanalysis, the coupled model simulates the main characteris tics of global atmospheric circulation and the fields of temperature and moisture. In particular, the simu lated precipitation and surface air temperature have sound results. The work creates a solid base on coupling climate models with the biosphere.展开更多
In this study, numerical simulation of a two-dimensional convective-dispersive model in Hakata Bay, Japan, is performed to analyze the impact of major river discharges due to torrential rain in Fukuoka City. Tank mode...In this study, numerical simulation of a two-dimensional convective-dispersive model in Hakata Bay, Japan, is performed to analyze the impact of major river discharges due to torrential rain in Fukuoka City. Tank models are applied to calculate river discharges, which are taken into consideration as river inflow in the hydrodynamic model of Hakata Bay. A two-way nesting “edge” technique is developed and applied in the model in order to consider the influence of narrow and complex geographical features. The area around “Island City” and Imazu Bay are calculated in high resolution. The resulting model has high reproducibility since the calculated river discharges, tidal current, and salinity show good agreement with observed data. To analyze the impact of large river discharges, the calculation period is set from 11 September 2002 to 21 September 2002 since there was torrential rain on September 16 in the given year in Fukuoka City (163.5 mm/d). The results show that low-salinity water covered the whole of the inner part of Hakata Bay, and water of lower salinity than outer sea water (<34.0 psu) spread out to the bay’s mouth two days after the torrential rain event. Fresh water covered the entire area of Imazu Bay and flowed out from the mouth of the Bay after the torrential rain event. The behavior of fresh water after a few days of torrential rain was remarkably different from normal discharge river flow. These results indicate that the environment in Imazu Bay can be degraded severely by torrential rain. Therefore, countermeasures to protect ecosystems in Hakata Bay must be examined immediately.展开更多
By means of vertical normal modes a regional nested multilevel primitive equation model can be reduced to several sets of shallow water equations characterized by various equivalent depths. Therefore, time integration...By means of vertical normal modes a regional nested multilevel primitive equation model can be reduced to several sets of shallow water equations characterized by various equivalent depths. Therefore, time integration of the model in spectral form can be performed in the manner similar to those used in the spectral nested shallow water equation model case.展开更多
A method to expand meteorological elements in terms of finite double Fourier series in a limited-region and a spectral nested shallow water equation model based upon the method with conformal map projection in rectang...A method to expand meteorological elements in terms of finite double Fourier series in a limited-region and a spectral nested shallow water equation model based upon the method with conformal map projection in rectangular coordinates, have been proposed, and computational stability and efficiency of time integration have been discussed.展开更多
A baroclinic typhoon model with a moving multi--nested grid is applied in marine environmental forecasts. This paper describes the numerical methods of the model including governing equations, finite differencing, spl...A baroclinic typhoon model with a moving multi--nested grid is applied in marine environmental forecasts. This paper describes the numerical methods of the model including governing equations, finite differencing, split scheme and time integration.展开更多
文摘As a western boundary current, the Kuroshio is closely related to the large scale oceanic circulation and at the same time, is greatly influenced by the local topography because of its narrow width. Numerical studies of the Kuroshio are usually confined to portions of it in different geographical regions since the computer execution time required to run a numerical model of the Pacific using a sufficiently fine grid to resolve adequately the flow structure of the Kuroshio is enormous. In order to circumvent the problems of multiple spatial scales and consistent boundary conditions, nested models are employed in which a coarse grid model of the Pacific is used to supply the open boundary conditions for a finer grid model of the northwestern Pacific to simulate the flow and temperature fields of the Kuroshio in summer and winter. The major features of the Kuroshio have in general been successfully simulated by the nested models.
基金This work was supported by the National Natural Science Foundation of China under Grant No.49735170.
文摘This paper presents a numerical study on the 1998 summer rainfall over the Yangtze River valley in central and eastern China, addressing effect of a nested area size on simulations in terms of the technique of nesting a regional climate model (RCM) upon a general circulation model (GCM). Evidence suggests that the size exerts greater impacts upon regional climate of the country, revealing that a larger nested size is superior to a small one for simulation in mitigating errors of GCM-provided lateral boundary forcing. Also, simulations show that the RCM should incorporate regions of climate systems of great importance into study and a low-resolution GCM yields more pronounced errors as a rule when used in the research of the Tibetan Plateau, and, in contrast, our PσRCM can do a good job in describing the plateau’s role in a more realistic and accurate way. It is for this reason that the tableland should be included in the nested area when the RCM is employed to investigate the regional climate. Our PσRCM nesting upon a GCM reaches more realistic results compared to a single GCM used.
文摘Grey heron (Ardea cimerca) is one kind of the great birds which are often seen in the northeast marsh area of P.R.China, and there are many grey herons to reproduce in Zhalong Nature Reserve from March to August annually. In this paper, through the inveingation of the grey herons nesting habitat and according to the water depth, vegetation type, cover density and plan heigh of the nesting place, the grey heron’s nesting habitat suitability index medes are established. The main model is s=(s1xs2xs3xs4)1/4,where s1 is the water depth suitability index, s2 is the vegetation type suitability index, s3 is the cover density index, sa is the plant height suitability index. These models provide a kind of reliable method for evaluating the habitat quality of the grey heron’s nesting.
文摘Today, the nested model is used widely. The effect and role of each nested variate is analyzed in this paper. It is found that the forecast could benefit by nesting part of the variates and the effect of each of the variates may be different. Therefore, only the effectual variates are chosen for the nesting. According to this finding, a scheme is suggested and applied to the limited area mode (TL10) nested with global spectral mode (T63) for forecasting tropical cyclones over the South China Sea. A few numerical prediction tests show that this scheme is reasonable and efficient.
文摘A bogus typhoon scheme,designed for the initialization of a typhoon track prediction model,is developed in thispaper.This scheme includes both effects of axisymmetric wind and asymmetric wind.Experimental forecasts using atwo-way interactive movable nested mesh model show that the forecast skill of typhoon tracks has clearly improvedafter introducing the bogus typhoon into the initial fields.
基金This paper is financially supported by the NKBRSF(National Key Basic Research Special Funds)project ofChina(G1999043400).the Key Project of Knowledge Innovation Engineering of Chinese Academy of Sciences(ZKCX2-SW-210),and the Lead Project of Innovation
文摘An atmosphere-vegetation interaction model (AVIM) has been coupled with a nine-layer General Cir culation Model (GCM) of Institute of Atmospheic Physics / State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (IAP/ LASG), which is rhomboidally truncated at zonal wave number 15, to simulate global climatic mean states. AVIM is a model having inter-feedback between land surface processes and eco-physiological processes on land. As the first step to couple land with atmosphere completely, the physiological processes are fixed and only the physical part (generally named the SVAT (soil-vegetation-atmosphere-transfer scheme) model) of AVIM is nested into IAP/ LASG L9R15 GCM. The ocean part of GCM is prescribed and its monthly sea surface temperature (SST) is the climatic mean value. With respect to the low resolution of GCM, i.e., each grid cell having lon gitude 7.5?and latitude 4.5? the vegetation is given a high resolution of 1.5?by 1.5?to nest and couple the fine grid cells of land with the coarse grid cells of atmosphere. The coupling model has been integrated for 15 years and its last ten-year mean of outputs was chosen for analysis.Compared with observed data and NCEP reanalysis, the coupled model simulates the main characteris tics of global atmospheric circulation and the fields of temperature and moisture. In particular, the simu lated precipitation and surface air temperature have sound results. The work creates a solid base on coupling climate models with the biosphere.
文摘In this study, numerical simulation of a two-dimensional convective-dispersive model in Hakata Bay, Japan, is performed to analyze the impact of major river discharges due to torrential rain in Fukuoka City. Tank models are applied to calculate river discharges, which are taken into consideration as river inflow in the hydrodynamic model of Hakata Bay. A two-way nesting “edge” technique is developed and applied in the model in order to consider the influence of narrow and complex geographical features. The area around “Island City” and Imazu Bay are calculated in high resolution. The resulting model has high reproducibility since the calculated river discharges, tidal current, and salinity show good agreement with observed data. To analyze the impact of large river discharges, the calculation period is set from 11 September 2002 to 21 September 2002 since there was torrential rain on September 16 in the given year in Fukuoka City (163.5 mm/d). The results show that low-salinity water covered the whole of the inner part of Hakata Bay, and water of lower salinity than outer sea water (<34.0 psu) spread out to the bay’s mouth two days after the torrential rain event. Fresh water covered the entire area of Imazu Bay and flowed out from the mouth of the Bay after the torrential rain event. The behavior of fresh water after a few days of torrential rain was remarkably different from normal discharge river flow. These results indicate that the environment in Imazu Bay can be degraded severely by torrential rain. Therefore, countermeasures to protect ecosystems in Hakata Bay must be examined immediately.
文摘By means of vertical normal modes a regional nested multilevel primitive equation model can be reduced to several sets of shallow water equations characterized by various equivalent depths. Therefore, time integration of the model in spectral form can be performed in the manner similar to those used in the spectral nested shallow water equation model case.
文摘A method to expand meteorological elements in terms of finite double Fourier series in a limited-region and a spectral nested shallow water equation model based upon the method with conformal map projection in rectangular coordinates, have been proposed, and computational stability and efficiency of time integration have been discussed.
基金supported by the Chinese National Research Program of Science and Technology under Project! 85-903-03-04.
文摘A baroclinic typhoon model with a moving multi--nested grid is applied in marine environmental forecasts. This paper describes the numerical methods of the model including governing equations, finite differencing, split scheme and time integration.
