1991 Vol. 8, No. 4
Display Method:
1991, 8(4): 383-398.
doi: 10.1007/BF02919262
Abstract:
This survey is concerned with the new developments on existence and uniqueness of solutions of some basic mod-els in atmospheric dynamics, such as two-and three-dimensional quasi-geostrophic models and three-dimensional balanced model. The main aim of this paper is to introduce some results about the global and local (with respect to time) existence of solutions given by the authors in recent years, but others' important contributions and the literature on this subject are also quoted. We discuss briefly the relationships among the existence and uniqueness, physical in-stability and computational instability. In the appendixes, some key mathematical techniques in obtaining our results are presented, which are of vital importance to other problems in geophysical fluid dynamics as well.
This survey is concerned with the new developments on existence and uniqueness of solutions of some basic mod-els in atmospheric dynamics, such as two-and three-dimensional quasi-geostrophic models and three-dimensional balanced model. The main aim of this paper is to introduce some results about the global and local (with respect to time) existence of solutions given by the authors in recent years, but others' important contributions and the literature on this subject are also quoted. We discuss briefly the relationships among the existence and uniqueness, physical in-stability and computational instability. In the appendixes, some key mathematical techniques in obtaining our results are presented, which are of vital importance to other problems in geophysical fluid dynamics as well.
1991, 8(4): 399-406.
doi: 10.1007/BF02919263
Abstract:
In this part, the temporal evolution and interaction across the equator of 30-50 day oscillation in the atmosphere are investigated further. The annual variation of 30-50 day oscillation is quite obvious in the mid-high latitudes. In the tropical atmosphere, the obvious interannual variation is an important property for temporal evolution of 30-50 day oscillation. The low-frequency wavetrain across the equator over the central Pacific and central Atlantic area, the movement of the long-lived low-frequency system across the equator and the meridional wind component across the equator will obviously show the interaction of 30-50 day oscillation in the atmosphere across the equator.
In this part, the temporal evolution and interaction across the equator of 30-50 day oscillation in the atmosphere are investigated further. The annual variation of 30-50 day oscillation is quite obvious in the mid-high latitudes. In the tropical atmosphere, the obvious interannual variation is an important property for temporal evolution of 30-50 day oscillation. The low-frequency wavetrain across the equator over the central Pacific and central Atlantic area, the movement of the long-lived low-frequency system across the equator and the meridional wind component across the equator will obviously show the interaction of 30-50 day oscillation in the atmosphere across the equator.
1991, 8(4): 407-420.
doi: 10.1007/BF02919264
Abstract:
In this paper the concept of Chaos and its applications to the study of predictability theory is introduced. The au-thor’s attempt is to give a general overview of ideas and methods involved in this problem to scientists, who are inter-ested in the problem of predictability but not familiar with the theory of chaos. The problem is discussed in 4 sections. In the first section, the concept of chaos and the study methods are outlined briefly; in the second section, the methods of quantitatively measuring the main characteristics of chaos which are the basis for the predictability theory are in-troduced; the third section discusses the time series analysis for directly studying chaotic phenomena in practical prob-lems; and the last section presents some research results on the chaotic characteristics and the predictability of the real atmosphere.
In this paper the concept of Chaos and its applications to the study of predictability theory is introduced. The au-thor’s attempt is to give a general overview of ideas and methods involved in this problem to scientists, who are inter-ested in the problem of predictability but not familiar with the theory of chaos. The problem is discussed in 4 sections. In the first section, the concept of chaos and the study methods are outlined briefly; in the second section, the methods of quantitatively measuring the main characteristics of chaos which are the basis for the predictability theory are in-troduced; the third section discusses the time series analysis for directly studying chaotic phenomena in practical prob-lems; and the last section presents some research results on the chaotic characteristics and the predictability of the real atmosphere.
1991, 8(4): 421-430.
doi: 10.1007/BF02919265
Abstract:
A global mean ocean model including atmospheric heating, heat capacity of the mixed layer ocean, and vertical thermal diffusivity in the lower ocean, proposed by Cess and Goldenberg (1981), is used in this paper to study the sen-sitivity of global warming to the vertical diffusivity. The results suggest that the behaviour of upper ocean tempera-ture is mainly determined by the magnitude of upper layer diffusivity and an ocean with a larger diffusivity leads to a less increase of sea surface temperature and a longer time delay for the global warming induced by increasing CO2 than that with smaller one. The global warming relative to four scenarios of CO2 emission assumed by Intergovernmental Panel of Climate Change (IPCC) is also estimated by using the model with two kinds of thermal diffusivities. The result shows that for various combinations of the CO2 emission scenarios and the diffusivities, the oceanic time delay to the global warming varies from 15 years to 70 years.
A global mean ocean model including atmospheric heating, heat capacity of the mixed layer ocean, and vertical thermal diffusivity in the lower ocean, proposed by Cess and Goldenberg (1981), is used in this paper to study the sen-sitivity of global warming to the vertical diffusivity. The results suggest that the behaviour of upper ocean tempera-ture is mainly determined by the magnitude of upper layer diffusivity and an ocean with a larger diffusivity leads to a less increase of sea surface temperature and a longer time delay for the global warming induced by increasing CO2 than that with smaller one. The global warming relative to four scenarios of CO2 emission assumed by Intergovernmental Panel of Climate Change (IPCC) is also estimated by using the model with two kinds of thermal diffusivities. The result shows that for various combinations of the CO2 emission scenarios and the diffusivities, the oceanic time delay to the global warming varies from 15 years to 70 years.
1991, 8(4): 431-446.
doi: 10.1007/BF02919266
Abstract:
Inertia-gravity waves play an increasingly important role in the middle atmosphere dynamics. As a result, more attention has been paid to the study of inertia-gravity waves, especially to the middle atmosphere gravity waves. This paper presents some aspects of inertia-gravity waves with emphasis on the propagation. Two methods are used here, namely, geometric optical method and physical optical method. We can see from the study that inertia-gravity waves are similar to planetary waves in some respects and they are different from planetary waves in others.
Inertia-gravity waves play an increasingly important role in the middle atmosphere dynamics. As a result, more attention has been paid to the study of inertia-gravity waves, especially to the middle atmosphere gravity waves. This paper presents some aspects of inertia-gravity waves with emphasis on the propagation. Two methods are used here, namely, geometric optical method and physical optical method. We can see from the study that inertia-gravity waves are similar to planetary waves in some respects and they are different from planetary waves in others.
1991, 8(4): 447-458.
doi: 10.1007/BF02919267
Abstract:
A 2-D zonally averaged, time dependent climate model is developed to study the biosphere-atmosphere interaction. A numerical scheme is specifically designed for the model to ensure the conservation of mass, momentum, energy, and water vapor. A simple parameterization of vegetation-soil layers is incorporated in this 2-D model. Us-ing this coupled model, we study the biosphere and atmosphere interaction. Some preliminary results concerning the African drought with annual mean conditions are presented.
A 2-D zonally averaged, time dependent climate model is developed to study the biosphere-atmosphere interaction. A numerical scheme is specifically designed for the model to ensure the conservation of mass, momentum, energy, and water vapor. A simple parameterization of vegetation-soil layers is incorporated in this 2-D model. Us-ing this coupled model, we study the biosphere and atmosphere interaction. Some preliminary results concerning the African drought with annual mean conditions are presented.
1991, 8(4): 459-470.
doi: 10.1007/BF02919268
Abstract:
A numerical model with the p-sigma incorporated coordinate system and primitive equations is used to simulate the effect of initial soil moisture in desert areas on the climate change. The results show that the present deserts have a tendency to expand. When the initial soil moisture in the desert regions increases, the desert areas will shrink but can not disappear. The small deserts may not remain any longer when there are sources of water vapour around. Both the land-sea contrast and the topography are the background conditions of the present desert distribution through the mechanism of the downdrafts and the rare precipitation over the desert regions. The increase of the initial desert soil moisture will weaken the summer monsoon circulation and, consequently, the monsoonal precipitation.
A numerical model with the p-sigma incorporated coordinate system and primitive equations is used to simulate the effect of initial soil moisture in desert areas on the climate change. The results show that the present deserts have a tendency to expand. When the initial soil moisture in the desert regions increases, the desert areas will shrink but can not disappear. The small deserts may not remain any longer when there are sources of water vapour around. Both the land-sea contrast and the topography are the background conditions of the present desert distribution through the mechanism of the downdrafts and the rare precipitation over the desert regions. The increase of the initial desert soil moisture will weaken the summer monsoon circulation and, consequently, the monsoonal precipitation.
1991, 8(4): 471-478.
doi: 10.1007/BF02919269
Abstract:
Over twenty thousand lightning location data obtained by using Lightning Location System (LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning, strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relationship between DF display and lightning radiation electric field, discharge current is obtained.
Over twenty thousand lightning location data obtained by using Lightning Location System (LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning, strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relationship between DF display and lightning radiation electric field, discharge current is obtained.
1991, 8(4): 479-488.
doi: 10.1007/BF02919270
Abstract:
Diagnostic analysis of the balance of kinetic energy (KE) is made for a decaying onland typoon, its external tor-rential rain area and environment. Results show that, besides low-level frictional dissipation as an energy sink, upper-level horizontal export of KE is another important one for the typhoon. In its decaying KE grows in the exter-nal torrential rain area, and the KB production term Gk represents the chief energy source for the torrential rain. The growth of Gk is attributed to the development of the heavy rain and to the heating effect of released latent heat, and the external torrential rain owes its evolution to the exported KE from the strong windbelt in the east of the ty-phoon and the conversion of synoptic KE into mesoscale perturbation KE. The development of the torrential rain re-sults in the KE feedback to its environment. The KG transfer from toe typhoon to the external torrential rain area and then to the environmental region as a mechanism constitutes one of the causes for the rapid disintegration of the tempest.
Diagnostic analysis of the balance of kinetic energy (KE) is made for a decaying onland typoon, its external tor-rential rain area and environment. Results show that, besides low-level frictional dissipation as an energy sink, upper-level horizontal export of KE is another important one for the typhoon. In its decaying KE grows in the exter-nal torrential rain area, and the KB production term Gk represents the chief energy source for the torrential rain. The growth of Gk is attributed to the development of the heavy rain and to the heating effect of released latent heat, and the external torrential rain owes its evolution to the exported KE from the strong windbelt in the east of the ty-phoon and the conversion of synoptic KE into mesoscale perturbation KE. The development of the torrential rain re-sults in the KE feedback to its environment. The KG transfer from toe typhoon to the external torrential rain area and then to the environmental region as a mechanism constitutes one of the causes for the rapid disintegration of the tempest.
1991, 8(4): 489-498.
doi: 10.1007/BF02919271
Abstract:
By using a nine-layer global spectral model involving fuller parameterization of physical processes, with a rhomboidal truncation at wavenumber 15, experiments are performed in terms of two numerical schemes, one with long-term mean coverage of Arctic ice (Exp.1), the other without the ice (Exp.2). Results indicate that the Arctic re-gion is a heat source in Exp.2 relative to the case in Exp.1. Under the influence of the polar heat source simulated, there still exist stationary wavetrains that produce WA-EUP and weak PNA patterns in Northern winter. That either the Arctic or the tropical heat source can cause identical climatic effects is due to the fact that the anomaly of the Arc-tic ice cover will directly induce a south-propagating wavetrain, and bring about the redistribution of the tropical heat source/ sink. The redistribution is responsible for new wavetrains that will exert impact on the global climate. The simulation results bear out further that the polar region in Exp.2 as a heat source, can produce, by local forcing, a pair of positive and negative difference centers, which circle the Arctic moving eastwards. Observed in the Northern Hemisphere extratropics is a 40-50 day oscillation in relation to the moving pair, both having the same period.
By using a nine-layer global spectral model involving fuller parameterization of physical processes, with a rhomboidal truncation at wavenumber 15, experiments are performed in terms of two numerical schemes, one with long-term mean coverage of Arctic ice (Exp.1), the other without the ice (Exp.2). Results indicate that the Arctic re-gion is a heat source in Exp.2 relative to the case in Exp.1. Under the influence of the polar heat source simulated, there still exist stationary wavetrains that produce WA-EUP and weak PNA patterns in Northern winter. That either the Arctic or the tropical heat source can cause identical climatic effects is due to the fact that the anomaly of the Arc-tic ice cover will directly induce a south-propagating wavetrain, and bring about the redistribution of the tropical heat source/ sink. The redistribution is responsible for new wavetrains that will exert impact on the global climate. The simulation results bear out further that the polar region in Exp.2 as a heat source, can produce, by local forcing, a pair of positive and negative difference centers, which circle the Arctic moving eastwards. Observed in the Northern Hemisphere extratropics is a 40-50 day oscillation in relation to the moving pair, both having the same period.
1991, 8(4): 499-504.
doi: 10.1007/BF02919272
Abstract:
Sun et al., (1983) have given some favourable environmental conditions and have shown that there are four common features in convective rainstorms. In this paper, an important process of evolution of cloud systems was re-vealed when heavy rainfall occurred based on the diagnostic analysis of heavy rainfall cases. When the different cloud systems merge into a large one, the mesoscale heavy rainfall occurs and enhances. In other words, the process of evo-lution of cloud systems emphasized in this paper is the process of interaction between two cloud systems when the heavy rainfall occurs. The favourable environmental condition is also investigated.
Sun et al., (1983) have given some favourable environmental conditions and have shown that there are four common features in convective rainstorms. In this paper, an important process of evolution of cloud systems was re-vealed when heavy rainfall occurred based on the diagnostic analysis of heavy rainfall cases. When the different cloud systems merge into a large one, the mesoscale heavy rainfall occurs and enhances. In other words, the process of evo-lution of cloud systems emphasized in this paper is the process of interaction between two cloud systems when the heavy rainfall occurs. The favourable environmental condition is also investigated.
1991, 8(4): 505-509.
doi: 10.1007/BF02919273
Abstract:
A case study of the convectively driven monsoon boundary layer has been carried out using the aerological ob-servations at four stations in the region of monsoon trough during Monsoon Trough Boundary Layer Experiment (MONTBLEX) 1988. The Convective Boundary Layer (CBL) in the region of monsoon trough did not show double mixing line structure. A single mixing line representing the CBL with different stabilities with respect to the convective activities was observed.
A case study of the convectively driven monsoon boundary layer has been carried out using the aerological ob-servations at four stations in the region of monsoon trough during Monsoon Trough Boundary Layer Experiment (MONTBLEX) 1988. The Convective Boundary Layer (CBL) in the region of monsoon trough did not show double mixing line structure. A single mixing line representing the CBL with different stabilities with respect to the convective activities was observed.
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