1987 Vol. 4, No. 4
Display Method:
1987, 4(4): 375-384.
doi: 10.1007/BF02656738
Abstract:
The aim of this paper is to examine whether an axisymmetric tropical model with thermal driving and orographic forcing can produce multiple equilibria in relation to the monsoon circulation over South Asia. The model is an equivalent barotropic balanced equatorial β-plane model. It shows that there may exist mul-tiple flow equilibria for a given driving, of which two may be stable: one corresponds to the summer monsoon, and the other to the winter monsoon circulation. The transition between them is also discussed.
The aim of this paper is to examine whether an axisymmetric tropical model with thermal driving and orographic forcing can produce multiple equilibria in relation to the monsoon circulation over South Asia. The model is an equivalent barotropic balanced equatorial β-plane model. It shows that there may exist mul-tiple flow equilibria for a given driving, of which two may be stable: one corresponds to the summer monsoon, and the other to the winter monsoon circulation. The transition between them is also discussed.
1987, 4(4): 385-394.
doi: 10.1007/BF02656739
Abstract:
In this paper, the anomaly of disturbance height field over Northern Hemisphere due to SST anomaly in the tropical Atlantic Ocean is simulated by using the general circulation model of IAP. A quasi-geostrophic, 34-level spherical coordinate model is also used to compute the distribution of atmospheric circulation anomaly when there is an anomaly of heat source over the tropical Atlantic. The computed results show that, owing to the heat source anomaly over the tropical Atlantic, the EU-pattern anomaly in the winter circulation may be caused. Namely, a ridge will be enhanced over the northwest Europe, a trough will be deepened over Siberia, but a positive anomaly of disturbance height field will be formed over the northeast China, Japan and other areas of East Asia. Moreover, the numerically simulated results show that the above-mentioned EU-pattern anomalies of circulation are due to the propagations of planetary wave train. About 15 days after an anomaly of the beat source over the tropical Atlantic is injected, the EU-pattern anomaly of atmospheric circulation is formed. This is in good agreement with the results analysed theoretically.
In this paper, the anomaly of disturbance height field over Northern Hemisphere due to SST anomaly in the tropical Atlantic Ocean is simulated by using the general circulation model of IAP. A quasi-geostrophic, 34-level spherical coordinate model is also used to compute the distribution of atmospheric circulation anomaly when there is an anomaly of heat source over the tropical Atlantic. The computed results show that, owing to the heat source anomaly over the tropical Atlantic, the EU-pattern anomaly in the winter circulation may be caused. Namely, a ridge will be enhanced over the northwest Europe, a trough will be deepened over Siberia, but a positive anomaly of disturbance height field will be formed over the northeast China, Japan and other areas of East Asia. Moreover, the numerically simulated results show that the above-mentioned EU-pattern anomalies of circulation are due to the propagations of planetary wave train. About 15 days after an anomaly of the beat source over the tropical Atlantic is injected, the EU-pattern anomaly of atmospheric circulation is formed. This is in good agreement with the results analysed theoretically.
1987, 4(4): 395-402.
doi: 10.1007/BF02656740
Abstract:
Using summer data of seven years (1973 to 1979), the authors investigated the medium-range oscillations of the parameters which represent the circulation and synoptic scale systems of tropical atmosphere in the area between 30oE and 130oW and the parameters in the area of the middle and high latitudes of the Northern Hemisphere, with more attention paid to the interannual steadiness of parameters with periodic oscillation. Though the parameters investigated are as many as 148, only a few have been found to have medium-range oscillations of which the interannual variability is relatively small. These oscillation systems are characterized by regional distribution. Relations among those parameters with annually steady oscillations have also been investigated.
Using summer data of seven years (1973 to 1979), the authors investigated the medium-range oscillations of the parameters which represent the circulation and synoptic scale systems of tropical atmosphere in the area between 30oE and 130oW and the parameters in the area of the middle and high latitudes of the Northern Hemisphere, with more attention paid to the interannual steadiness of parameters with periodic oscillation. Though the parameters investigated are as many as 148, only a few have been found to have medium-range oscillations of which the interannual variability is relatively small. These oscillation systems are characterized by regional distribution. Relations among those parameters with annually steady oscillations have also been investigated.
1987, 4(4): 403-413.
doi: 10.1007/BF02656741
Abstract:
A computational method for the mean slab transmissivities of water vapour and CO2 and a recurrence me-thod for the atmospheric cooling rate due to infrared radiation are developed and discussed in some detail in this paper.At first the spectra of water vapour and CO2 are divided into 10 and 2 basic bands according to the experi-mental data; then an analytic and universal expression of the mean slab transmissivity in those bands is obtained and checked with the experimental data at 220o, 260o and 300oK. Results show that the computational method developed in this paper has quite good accuracy, and therefore it can be used in the GCMs for calculations of the atmospheric cooling rates.The recurrence method for calculations of the upward and the downward fluxes of infrared radiation is de-rived and checked. It is proved that the method has a similar accuracy as others, but saves a lot of computation time. At last a simplified method of the transmissivity calculation, i.e. the tabulation method, is developed and its accuracy is checked as well.
A computational method for the mean slab transmissivities of water vapour and CO2 and a recurrence me-thod for the atmospheric cooling rate due to infrared radiation are developed and discussed in some detail in this paper.At first the spectra of water vapour and CO2 are divided into 10 and 2 basic bands according to the experi-mental data; then an analytic and universal expression of the mean slab transmissivity in those bands is obtained and checked with the experimental data at 220o, 260o and 300oK. Results show that the computational method developed in this paper has quite good accuracy, and therefore it can be used in the GCMs for calculations of the atmospheric cooling rates.The recurrence method for calculations of the upward and the downward fluxes of infrared radiation is de-rived and checked. It is proved that the method has a similar accuracy as others, but saves a lot of computation time. At last a simplified method of the transmissivity calculation, i.e. the tabulation method, is developed and its accuracy is checked as well.
1987, 4(4): 414-431.
doi: 10.1007/BF02656742
Abstract:
An improved new wedge-shaped chamber of ice thermal diffusion has been used to get a more complete and overall growth law of ice crystals. Based on more than 4,000 data, a quantitative growth law of ice crystals in an ice supersaturation and temperature field has been presented. A new method for quantitatively indicating the form of different kinds of ice crystals has been suggested. The growth rates of ice crystals at different tempera-tures and ice supersaturations have been studied. A quantitative comparison of static and dynamic experiments for ice crystal growth has also been presented. Finally, the author gives new models of ice crystal growth law in temperature-ice supersaturation or vapor density excess field.
An improved new wedge-shaped chamber of ice thermal diffusion has been used to get a more complete and overall growth law of ice crystals. Based on more than 4,000 data, a quantitative growth law of ice crystals in an ice supersaturation and temperature field has been presented. A new method for quantitatively indicating the form of different kinds of ice crystals has been suggested. The growth rates of ice crystals at different tempera-tures and ice supersaturations have been studied. A quantitative comparison of static and dynamic experiments for ice crystal growth has also been presented. Finally, the author gives new models of ice crystal growth law in temperature-ice supersaturation or vapor density excess field.
1987, 4(4): 432-446.
doi: 10.1007/BF02656743
Abstract:
The zonal and meridional circulations and their variability are examined on the basis of the surface wind data for 1950-1979. The climatological mean zonal wind and its divergence are examined in reference to the Walker Circulation. The role played by the meridional circulation in contributing to convergence of the surface wind field within the equatorial zone is emphasized. Regression coefficients are used to infer seasonal mean anomalies of divergence of the surface wind in years when the sea level pressure is 1 hPa above normal at Darwin, a condition representative of El Nino events. It is shown that anomalies in the divergence associated with the meridional wind component are primarily responsible for the heavy precipitation in the Central Pacific, while the anomalous divergence associated with the zonal wind component may cause the drought in the Western Pacific near Indonesia. A similar pattern of divergence anomalies is evident during three consecutive seasons beginning in northern summer and ending in northern winter. The reinforcement of the Hadley Circulation during El Nino episodes is noted. It is shown that the circulations over the Atlantic Ocean and Pacific Ocean are relatively uncorrelated. The interrelation between the dipole anticyclones and the meridional cir-culation over the central Pacific is discussed.
The zonal and meridional circulations and their variability are examined on the basis of the surface wind data for 1950-1979. The climatological mean zonal wind and its divergence are examined in reference to the Walker Circulation. The role played by the meridional circulation in contributing to convergence of the surface wind field within the equatorial zone is emphasized. Regression coefficients are used to infer seasonal mean anomalies of divergence of the surface wind in years when the sea level pressure is 1 hPa above normal at Darwin, a condition representative of El Nino events. It is shown that anomalies in the divergence associated with the meridional wind component are primarily responsible for the heavy precipitation in the Central Pacific, while the anomalous divergence associated with the zonal wind component may cause the drought in the Western Pacific near Indonesia. A similar pattern of divergence anomalies is evident during three consecutive seasons beginning in northern summer and ending in northern winter. The reinforcement of the Hadley Circulation during El Nino episodes is noted. It is shown that the circulations over the Atlantic Ocean and Pacific Ocean are relatively uncorrelated. The interrelation between the dipole anticyclones and the meridional cir-culation over the central Pacific is discussed.
THE EFFECTS OF FRICTION AND HEATING OF CONVECTTVE CONDENSATION IN THE BAROCLINIC INSTABILITY PROBLEM
1987, 4(4): 447-459.
doi: 10.1007/BF02656744
Abstract:
By using the β-plane, two-layer quasi-geostrophic baroclinic model, this paper discusses the baroclinic in-stability problem concerning the effects of friction and heating of convective condensation. By Linear analysis it is shown that the combination of β effect, friction and convective heating brings about the asymmetric phenom-enon of margin curves. The convective heating plays a role in the increased baroclinic instability. As the heating increases (m*→1), the short wave cutoff can increase infinitely. Besides, the numerical integration of the finite-amplitude equations shows that the trajectory on the phase plane oscillates periodically in the case of non-dissipation. When the friction dissipation is considered, the trajectory of phase decays and oscillates to the equilibrium. The stronger convective heating not only makes the unstable wave length shorter and the amplitude of the equilibrium decrease, but also makes multiple equilibrium into single equilibrium.
By using the β-plane, two-layer quasi-geostrophic baroclinic model, this paper discusses the baroclinic in-stability problem concerning the effects of friction and heating of convective condensation. By Linear analysis it is shown that the combination of β effect, friction and convective heating brings about the asymmetric phenom-enon of margin curves. The convective heating plays a role in the increased baroclinic instability. As the heating increases (m*→1), the short wave cutoff can increase infinitely. Besides, the numerical integration of the finite-amplitude equations shows that the trajectory on the phase plane oscillates periodically in the case of non-dissipation. When the friction dissipation is considered, the trajectory of phase decays and oscillates to the equilibrium. The stronger convective heating not only makes the unstable wave length shorter and the amplitude of the equilibrium decrease, but also makes multiple equilibrium into single equilibrium.
1987, 4(4): 460-470.
doi: 10.1007/BF02656745
Abstract:
A puff model is developed in this study, which simultaneously considers the Monte-Carlo technique, the time and space changes of atmospheric parameters, multiple continuity pollutant sources, linear chemical trans-formation and removal of pollutants, and the effect of complex terrain. The continuously observed turbulent statistical quantities, Lagrangian time scales, mesoscale flow field, and mixing layer depth in the PBL in the Dianchi area in China are directly put into the model, and the diurnal variations of air pollution are forecasted, which are dominated by such mesoscale local circulations as mountain and valley breeze, land and lake breeze, and city heat island (Kunming City). The results show that in the case of inputting the same data, they are in good agreement with the experimental data, as well as with the results of the three-dimensional advection-diffusion model (TD-ADM); the diurnal variation of mesoscale local circulation results in the obvious diurnal variation of mesoscale concentration distribution patterns; the Dianchi lake (appr. 300 km2) has a considerable effect on the distribution of air pollution in the area.
A puff model is developed in this study, which simultaneously considers the Monte-Carlo technique, the time and space changes of atmospheric parameters, multiple continuity pollutant sources, linear chemical trans-formation and removal of pollutants, and the effect of complex terrain. The continuously observed turbulent statistical quantities, Lagrangian time scales, mesoscale flow field, and mixing layer depth in the PBL in the Dianchi area in China are directly put into the model, and the diurnal variations of air pollution are forecasted, which are dominated by such mesoscale local circulations as mountain and valley breeze, land and lake breeze, and city heat island (Kunming City). The results show that in the case of inputting the same data, they are in good agreement with the experimental data, as well as with the results of the three-dimensional advection-diffusion model (TD-ADM); the diurnal variation of mesoscale local circulation results in the obvious diurnal variation of mesoscale concentration distribution patterns; the Dianchi lake (appr. 300 km2) has a considerable effect on the distribution of air pollution in the area.
1987, 4(4): 471-484.
doi: 10.1007/BF02656746
Abstract:
The resonance of topographically forced waves is studied using a quasi-geostrophic spectral model on the rotating sphere. The use of complete spectral expansions without truncation leads to the exact solutions of the nonlinear coupling equations by means of the random phase approximation and the projection operator techniques under the dissipation-vanishing limit. The energy transfer process between topographically forced wave ensemble and zonal mean flow is described.It is shown that the dynamical system loses stability and further bifurcation takes place when the to-pographic force has occurred. There are two sorts of equilibrium point in the resonance system. The unstable equilibrium is an isolated equilibrium point and, therefore, is hardly observed to occur. The stable equilibrium is an attractor set which is related to the phenomenon of blocking.
The resonance of topographically forced waves is studied using a quasi-geostrophic spectral model on the rotating sphere. The use of complete spectral expansions without truncation leads to the exact solutions of the nonlinear coupling equations by means of the random phase approximation and the projection operator techniques under the dissipation-vanishing limit. The energy transfer process between topographically forced wave ensemble and zonal mean flow is described.It is shown that the dynamical system loses stability and further bifurcation takes place when the to-pographic force has occurred. There are two sorts of equilibrium point in the resonance system. The unstable equilibrium is an isolated equilibrium point and, therefore, is hardly observed to occur. The stable equilibrium is an attractor set which is related to the phenomenon of blocking.
1987, 4(4): 485-495.
doi: 10.1007/BF02656747
Abstract:
The alternating change of the two meiyu front rain-bands caused by the alternating change between the moist potential vorticities is discussed. The main factors of the change of moist potential vorticity are the vertical and horizontal divergence of moist potential vorticity flux as well as the vertical transport caused by the cumulus mass flux. Also discussed is the possibility that the WAVE-CISK conditional symmetric instability in the baroclinic moist atmosphere leads to the forming of the double rain-bands and their roller-shaped circulation features. Theoretical analyses show that the latitudinal disturbance scale-selection by the primitive moisture model of the latent heat release in cumulus convection depends on the stratification instability parameter (Ri number) and viscous coefficient of eddy.
The alternating change of the two meiyu front rain-bands caused by the alternating change between the moist potential vorticities is discussed. The main factors of the change of moist potential vorticity are the vertical and horizontal divergence of moist potential vorticity flux as well as the vertical transport caused by the cumulus mass flux. Also discussed is the possibility that the WAVE-CISK conditional symmetric instability in the baroclinic moist atmosphere leads to the forming of the double rain-bands and their roller-shaped circulation features. Theoretical analyses show that the latitudinal disturbance scale-selection by the primitive moisture model of the latent heat release in cumulus convection depends on the stratification instability parameter (Ri number) and viscous coefficient of eddy.
1987, 4(4): 496-505.
doi: 10.1007/BF02656748
Abstract:
This paper outlines an expert system for predicting the regional heavy rain, including its structure, functions, characteristics, knowledge processing, inference performance, the running, results and conclusions.This system can accept, recognize, analyse, explain, understand, use, appreciate and refine the forecasting knowledge in MKL (Meteorological Knowledge Language) taught by meteorologists. The MKL language is good for describing meteorological knowledge and can represent almost all forecasting knowledge, thus ena-bling the system, with a great range of knowledge, to raise the processing abilities. The complex inference procedure can also be simplified by using MKL language.
This paper outlines an expert system for predicting the regional heavy rain, including its structure, functions, characteristics, knowledge processing, inference performance, the running, results and conclusions.This system can accept, recognize, analyse, explain, understand, use, appreciate and refine the forecasting knowledge in MKL (Meteorological Knowledge Language) taught by meteorologists. The MKL language is good for describing meteorological knowledge and can represent almost all forecasting knowledge, thus ena-bling the system, with a great range of knowledge, to raise the processing abilities. The complex inference procedure can also be simplified by using MKL language.
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