1984 Vol. 1, No. 1
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1984, 1(1): 1-6.
doi: 10.1007/BF03187610
Abstract:
Scientific publications as well as personal contacts at scientific meetings always give an impetus tothe advancement of science. Since the mid-seventies China has participatod in more and moreinternational conferences on atmospheric sciences. Especially in recent years china has actively takenpart in such interchanges. Beautiful as they are, the intricate Chinese characters, have given muchtrouble to our foreign colleagues in keeping abreast of the current developments in our atmospheric
Scientific publications as well as personal contacts at scientific meetings always give an impetus tothe advancement of science. Since the mid-seventies China has participatod in more and moreinternational conferences on atmospheric sciences. Especially in recent years china has actively takenpart in such interchanges. Beautiful as they are, the intricate Chinese characters, have given muchtrouble to our foreign colleagues in keeping abreast of the current developments in our atmospheric
1984, 1(1): 7-29.
doi: 10.1007/BF03187612
Abstract:
The most effective technique in long-range weather forecasting in China is teleconnection. Summer rainfall and temperatures are closely correlated to the preceding winter 500 mb heights over the Northern Hemisphere and sea surface temperatures over the North Pacific, so the former can be predicted from the latter. This kind of connection is called rhythm. In this paper, four examples of rhythm are outlined. The manifestation of rhythm and its universal significance is demonstrated. The mechanism of rhythm is discussed.
The most effective technique in long-range weather forecasting in China is teleconnection. Summer rainfall and temperatures are closely correlated to the preceding winter 500 mb heights over the Northern Hemisphere and sea surface temperatures over the North Pacific, so the former can be predicted from the latter. This kind of connection is called rhythm. In this paper, four examples of rhythm are outlined. The manifestation of rhythm and its universal significance is demonstrated. The mechanism of rhythm is discussed.
1984, 1(1): 19-39.
doi: 10.1007/BF03187613
Abstract:
Remote sensing of rainfall parameters by using laser scintillation effect, originally proposed by Wang et al. is a unique approach for getting rainfall rate and raindrop size distribution with excellent temporal and spatial representativeness. In this paper, we review Wang's work, point out the weakness of their basic equations, then establish a complete remote sensing equation in which the observable quantity, the scintillation of light intensity is used. The relationships between the rainfall parameters and the spatial-temporal correlation function of light scintilla tion are systematically discussed. Numerical investigations show that this equation gives at least four different ways to obtain the rainfall rate, and the kernel functions for raindrop size distribution are of excellent resolution. At last, the retrieval scheme of the drop size distribution is discussed.
Remote sensing of rainfall parameters by using laser scintillation effect, originally proposed by Wang et al. is a unique approach for getting rainfall rate and raindrop size distribution with excellent temporal and spatial representativeness. In this paper, we review Wang's work, point out the weakness of their basic equations, then establish a complete remote sensing equation in which the observable quantity, the scintillation of light intensity is used. The relationships between the rainfall parameters and the spatial-temporal correlation function of light scintilla tion are systematically discussed. Numerical investigations show that this equation gives at least four different ways to obtain the rainfall rate, and the kernel functions for raindrop size distribution are of excellent resolution. At last, the retrieval scheme of the drop size distribution is discussed.
1984, 1(1): 30-52.
doi: 10.1007/BF03187614
Abstract:
In this atmosphere-ocean-land coupled model, two basic ideas are developed, One is that the observational climate field is utilized and only the anomalous components are predicted. The other is that the transient Rossby wave is treated as the meteorological noise on the long-term variation that must be predicted in a climate forecasting. According to the latter, the transient Rossby wave can be filtered by omitting the partial derivative with respect to time in the atmospheric vorticity equation. But the time derivative term is still kept in the thermal equation for underlying ocean and land. With this assumption, the vorticity equation becomes time-independent, i.e. it is only a balance relationship between the anomaly geopotential height field and earth's surface heating field. This model is different from the usual GCM, so it may be called as the filtered anomaly model (FAM).A dozen examples of one month prediction are summarized in this report.
In this atmosphere-ocean-land coupled model, two basic ideas are developed, One is that the observational climate field is utilized and only the anomalous components are predicted. The other is that the transient Rossby wave is treated as the meteorological noise on the long-term variation that must be predicted in a climate forecasting. According to the latter, the transient Rossby wave can be filtered by omitting the partial derivative with respect to time in the atmospheric vorticity equation. But the time derivative term is still kept in the thermal equation for underlying ocean and land. With this assumption, the vorticity equation becomes time-independent, i.e. it is only a balance relationship between the anomaly geopotential height field and earth's surface heating field. This model is different from the usual GCM, so it may be called as the filtered anomaly model (FAM).A dozen examples of one month prediction are summarized in this report.
1984, 1(1): 40-61.
doi: 10.1007/BF03187615
Abstract:
The influences of the Tibetan Plateau and the Rocky Mountains on diurnal variations of the meteorological fields in July are investigated by use of a five-layer global atmospheric general circulation model which includes various physical processes, including diurnal variation of solar radiation and real topography. In this paper, a brief description of the model is given first and then we emphatically discuss the results by comparatively analysing the influences of the Tibetan Plateau and the Rocky Mountains on diurnal changes of temperature, the geopotential height, the horizontal and the vertical flows, as well as the vertical circulations in summer. The comparative analyses show that there are very prominent diurnal variations of temperature, geopotential height, wind fields and vertical circulations in the mountainous regions, the amplitudes of their variations are proportional to the scales of topography.
The influences of the Tibetan Plateau and the Rocky Mountains on diurnal variations of the meteorological fields in July are investigated by use of a five-layer global atmospheric general circulation model which includes various physical processes, including diurnal variation of solar radiation and real topography. In this paper, a brief description of the model is given first and then we emphatically discuss the results by comparatively analysing the influences of the Tibetan Plateau and the Rocky Mountains on diurnal changes of temperature, the geopotential height, the horizontal and the vertical flows, as well as the vertical circulations in summer. The comparative analyses show that there are very prominent diurnal variations of temperature, geopotential height, wind fields and vertical circulations in the mountainous regions, the amplitudes of their variations are proportional to the scales of topography.
1984, 1(1): 53-75.
doi: 10.1007/BF03187616
Abstract:
New solution techniques to improve the accuracy of quantitatively determining the atmospheric extinction coefficient and the backscattering-to-extinction ratio from lidar signals are developed. The integration method is proposed to analytically retrieve the extinction coefficient at ground level, which has the advantage of eliminating the effect of backscattering fluctuations on the inversion results.The ratio method, on the other hand, deals with the inversion of the vertical distribution of the extinction coefficient. The main idea of this method is to begin with a calculation of the transmittance by eliminating the backscattering through ratioing lidar signals at two elevations, and subsequently derive the extinction coefficient from the transmittance, thus avert from ambiguous results caused by inappropriate assumptions on the backscattering-to-extinction ratio. Observational investigations have demonstrated that the integration method is superior to the slope method in terms of accuracy and stability, and the ratio method is reasonable and feasible as well.
New solution techniques to improve the accuracy of quantitatively determining the atmospheric extinction coefficient and the backscattering-to-extinction ratio from lidar signals are developed. The integration method is proposed to analytically retrieve the extinction coefficient at ground level, which has the advantage of eliminating the effect of backscattering fluctuations on the inversion results.The ratio method, on the other hand, deals with the inversion of the vertical distribution of the extinction coefficient. The main idea of this method is to begin with a calculation of the transmittance by eliminating the backscattering through ratioing lidar signals at two elevations, and subsequently derive the extinction coefficient from the transmittance, thus avert from ambiguous results caused by inappropriate assumptions on the backscattering-to-extinction ratio. Observational investigations have demonstrated that the integration method is superior to the slope method in terms of accuracy and stability, and the ratio method is reasonable and feasible as well.
1984, 1(1): 62-83.
doi: 10.1007/BF03187617
Abstract:
Based on the data gathered during the Summer MONEX over the Bay of Bengal in July, 1979, a detailed observational study of the structure of a monsoon depression during the period of 3-8, July has been made. It has been revealed that the early disturbance of this depression was a mid-tropospheric cyclone. The subsequent rapid development was due mainly to the barotropic instability process of the basic zonal and meridional airflows.The cyclonic circulation of the depression extended in vertical upward to 500-400 mb level. Prior to the formation of the depression, the extremely strong westerly and northerly winds at the lower and middle levels, reaching the intensity of the low-level jet (22 m/s and 18.5 m/s, respectively), were observed. Post to the formation of the depression, a strong wind ring at the radius of 300-350 km from the depression center encircled the depression, with the wind maximum being at 850 mb. During this period, the maximum of the positive vorticity was of the magnitude of order of 10-4/s. The warm core at 400-300 mb was very remarkable. Finally, intrusion of the dry air over the depression may be an important factor leading to the weakening of the depression.
Based on the data gathered during the Summer MONEX over the Bay of Bengal in July, 1979, a detailed observational study of the structure of a monsoon depression during the period of 3-8, July has been made. It has been revealed that the early disturbance of this depression was a mid-tropospheric cyclone. The subsequent rapid development was due mainly to the barotropic instability process of the basic zonal and meridional airflows.The cyclonic circulation of the depression extended in vertical upward to 500-400 mb level. Prior to the formation of the depression, the extremely strong westerly and northerly winds at the lower and middle levels, reaching the intensity of the low-level jet (22 m/s and 18.5 m/s, respectively), were observed. Post to the formation of the depression, a strong wind ring at the radius of 300-350 km from the depression center encircled the depression, with the wind maximum being at 850 mb. During this period, the maximum of the positive vorticity was of the magnitude of order of 10-4/s. The warm core at 400-300 mb was very remarkable. Finally, intrusion of the dry air over the depression may be an important factor leading to the weakening of the depression.
1984, 1(1): 76-94.
doi: 10.1007/BF03187618
Abstract:
The acidity of precipitation in both clean and polluted areas was calculated for atmospheric CO2 and SO2 in equilibrium with water. pH values of 5 and 4.5 were obtained. In Beijing the pH value is increased due to paniculate chlorine reactivity and rainout of CaO in the atmosphere. The increase of pH value is related to liquid water content in cloud and the elemental concentrations of paniculate Cl and Ca in the atmosphere. This mechanism may help to explain the nonacid rain observed in Beijing where the air pollution problem is serious, as viewed by SO2 concentration and paniculate burden in the atmosphere.
The acidity of precipitation in both clean and polluted areas was calculated for atmospheric CO2 and SO2 in equilibrium with water. pH values of 5 and 4.5 were obtained. In Beijing the pH value is increased due to paniculate chlorine reactivity and rainout of CaO in the atmosphere. The increase of pH value is related to liquid water content in cloud and the elemental concentrations of paniculate Cl and Ca in the atmosphere. This mechanism may help to explain the nonacid rain observed in Beijing where the air pollution problem is serious, as viewed by SO2 concentration and paniculate burden in the atmosphere.
1984, 1(1): 84-104.
doi: 10.1007/BF03187619
Abstract:
The three-dimensional propagations of the forced stationary planetary waves in a realistic summer current, in which the vertical and horizontal wind shears are included, are discussed by using the refractive index squared of waves in a spherical coordinate system.The results show that there is no polar wave guide in stationary planetary wave propagations in summer. Thus, stationary planetary waves cannot propagate into the stratosphere. However, there are a wave guide pointing from the subtropics toward middle and high latitudes in the troposphere and another wave guide pointing from the lower troposphere at middle latitudes toward the upper troposphere near 30oN in the forced stationary planetary wave propagations.A linearized, steady-state, quasi-geostrophic 34-level spherical coordinate model with Rayleigh friction and Newtonian cooling, horizontal kinematic thermal diffusivity is used to simulate the wave guides of three-dimensional propagations of stationary planetary waves in summer.
The three-dimensional propagations of the forced stationary planetary waves in a realistic summer current, in which the vertical and horizontal wind shears are included, are discussed by using the refractive index squared of waves in a spherical coordinate system.The results show that there is no polar wave guide in stationary planetary wave propagations in summer. Thus, stationary planetary waves cannot propagate into the stratosphere. However, there are a wave guide pointing from the subtropics toward middle and high latitudes in the troposphere and another wave guide pointing from the lower troposphere at middle latitudes toward the upper troposphere near 30oN in the forced stationary planetary wave propagations.A linearized, steady-state, quasi-geostrophic 34-level spherical coordinate model with Rayleigh friction and Newtonian cooling, horizontal kinematic thermal diffusivity is used to simulate the wave guides of three-dimensional propagations of stationary planetary waves in summer.
1984, 1(1): 95-111.
doi: 10.1007/BF03187620
Abstract:
The structure of radar echo in stratiform cloud which was found in mei-yu frontal cloud system is generally inhomogeneous, especially in the structure of bright band echoes. The inhomogeneous structure of warm region in stratiform cloud and the shower feature of precipitation are closely related to the inhomogeneous structure of bright band and convective cells embedded in stratiform cloud.During Summer time the mei-yu cloud system is an important precipitating system in the southern part of China. To study its structure is of great significance for weather forecast and understanding the physical processes of cloud and precipitation. Therefore, we have observed mei-yu frontal cloud system by use of 711 type radar (3 cm) and airplane at Tunxi, Anhui Province since 1979. It was found that the structure of stratiform cloud, especially the structure of its warm region appears to be inhomogeneous1),2). This is a significant feature of cloud structure in mei-yu frontal cloud system. In this paper, we shall further analyse this inhomogeneous structure of stratiform cloud and study its effect on the precipitation.
The structure of radar echo in stratiform cloud which was found in mei-yu frontal cloud system is generally inhomogeneous, especially in the structure of bright band echoes. The inhomogeneous structure of warm region in stratiform cloud and the shower feature of precipitation are closely related to the inhomogeneous structure of bright band and convective cells embedded in stratiform cloud.During Summer time the mei-yu cloud system is an important precipitating system in the southern part of China. To study its structure is of great significance for weather forecast and understanding the physical processes of cloud and precipitation. Therefore, we have observed mei-yu frontal cloud system by use of 711 type radar (3 cm) and airplane at Tunxi, Anhui Province since 1979. It was found that the structure of stratiform cloud, especially the structure of its warm region appears to be inhomogeneous1),2). This is a significant feature of cloud structure in mei-yu frontal cloud system. In this paper, we shall further analyse this inhomogeneous structure of stratiform cloud and study its effect on the precipitation.
1984, 1(1): 105-118.
doi: 10.1007/BF03187621
Abstract:
The structure of thunderstorm in the atmospheric boundary layer in Beijing area is analysed by using three-year data of tower. It is indicated that the outflow current of the thunderstorm in the lower layer is a sort of density current. An area of evident wind direction shear is found at about half an hour to one hour before the arrival of the gust front.The maximum intensity of the shear can reach 0.35sec-1.The inner structure within the density current is also very complicated. At the nocturnal stable boundary layer in summertime, the development of the convective motions is often triggered due to the instability of the Kelvin-Helmholtz wave.
The structure of thunderstorm in the atmospheric boundary layer in Beijing area is analysed by using three-year data of tower. It is indicated that the outflow current of the thunderstorm in the lower layer is a sort of density current. An area of evident wind direction shear is found at about half an hour to one hour before the arrival of the gust front.The maximum intensity of the shear can reach 0.35sec-1.The inner structure within the density current is also very complicated. At the nocturnal stable boundary layer in summertime, the development of the convective motions is often triggered due to the instability of the Kelvin-Helmholtz wave.
1984, 1(1): 112-127.
doi: 10.1007/BF03187622
Abstract:
Measurements of absorption properties of some gases in the atmosphere were made by using CO line-tunable laser. Experimental equipment and method are briefly described. Absorption coefficients of NO, NO2, NH3, CO2 and H2O at some definite laser wavelengths are given, and variations of absorption properties with both partial and total pressures are discussed.
Measurements of absorption properties of some gases in the atmosphere were made by using CO line-tunable laser. Experimental equipment and method are briefly described. Absorption coefficients of NO, NO2, NH3, CO2 and H2O at some definite laser wavelengths are given, and variations of absorption properties with both partial and total pressures are discussed.
1984, 1(1): 119-139.
doi: 10.1007/BF03187623
Abstract:
In four seasons of 1982 measurements of atmospheric water vapor profiles and total precipitable water were made by a ground-based microwave radiometer operating at 1.35 cm wavelength. All data were processed by using Monte Carlo method. The statistical results of more than seventy cases show that the relative error compared to the radiosonde observations is 5.3% for the total precipitable water vapor and less than 20% for humidity profiles in the lower atmosphere below 750 mb. In addition, the relationship between the weather background and both the humidity profiles and the total precipitable water vapor were analyzed.
In four seasons of 1982 measurements of atmospheric water vapor profiles and total precipitable water were made by a ground-based microwave radiometer operating at 1.35 cm wavelength. All data were processed by using Monte Carlo method. The statistical results of more than seventy cases show that the relative error compared to the radiosonde observations is 5.3% for the total precipitable water vapor and less than 20% for humidity profiles in the lower atmosphere below 750 mb. In addition, the relationship between the weather background and both the humidity profiles and the total precipitable water vapor were analyzed.
1984, 1(1): 128-149.
doi: 10.1007/BF03187624
Abstract:
The onset of the 1979 summer monsoon is investigated using the ECMWF grid-point model. The role of the Tibetan Plateau in this process is investigated by means of parallel model integrations with different orographies. Similarly, the relative roles of land-sea thermal contrast, latent heat release and Southern Hemisphere influence are studied. The influence of the African Highland on the onset of the Somali jet is also explored. A generally satisfactory performance of the model in representing the onset of the monsoon is documented and various contributions to this from different model components are discussed. In Pan I of this paper the impact from the Southern Hemisphere is presented.
The onset of the 1979 summer monsoon is investigated using the ECMWF grid-point model. The role of the Tibetan Plateau in this process is investigated by means of parallel model integrations with different orographies. Similarly, the relative roles of land-sea thermal contrast, latent heat release and Southern Hemisphere influence are studied. The influence of the African Highland on the onset of the Somali jet is also explored. A generally satisfactory performance of the model in representing the onset of the monsoon is documented and various contributions to this from different model components are discussed. In Pan I of this paper the impact from the Southern Hemisphere is presented.
1984, 1(1): 1-18.
doi: 10.1007/BF03187611
Abstract:
Blocking is one of the intensive atmospheric disturbances which can maintain for a long time. In this paprer we investigate the general conditions favorable for the generation and maintenance of the intensive disturbances. First, the evolutional process of disturbances superimposed on a jet-like zonal flow is studied by using the wave-packet representation and the WKBJ method. Second, the mechanism for generation and maintenance of disturbances is investigated by using the nonlinear equations and the general physical laws. Finally, some numerical experiments are given for illustration, showing the rapid absorption of disturbances by the jet-like zonal flow in one case and the maintenance of disturbances for a long time in the other case.
Blocking is one of the intensive atmospheric disturbances which can maintain for a long time. In this paprer we investigate the general conditions favorable for the generation and maintenance of the intensive disturbances. First, the evolutional process of disturbances superimposed on a jet-like zonal flow is studied by using the wave-packet representation and the WKBJ method. Second, the mechanism for generation and maintenance of disturbances is investigated by using the nonlinear equations and the general physical laws. Finally, some numerical experiments are given for illustration, showing the rapid absorption of disturbances by the jet-like zonal flow in one case and the maintenance of disturbances for a long time in the other case.
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