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1994 Vol. 11, No. 1

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The Vertical Transport of Air Pollutants by Convective Clouds Part II: Transport of Soluble Gases and Sensitivity Tests
Kong Fanyou
1994, 11(1): 1-12. doi: 10.1007/BF02656988
A two-dimensional, non-reactive convective cloud transport model is used to simulate in detail the vertical transport and wet scavenging of soluble pollutant gases by a deep thunderstorm system, Simulations show that for gases with not very high solubility, a deep and intense thunderstorm can still rapidly and efficiently transport them from boundary layer (PBL) up to mid and upper troposphere, resulting in a local significant increase of concentration in the upper layer and a reduction in PBL. Dissolution effects decrease both the incloud gas concentration and the upward net fluxes. The higher the solubility is, the more remarkable the decrease is. However, for very low soluble gases (H < 102 M atm-1), the influences are very slight. In addition, the effects of irreversible dissolution and aqueous reactions in drops on the vertical transport of gaseous pollutants are estimated in extreme.
The Vertical Transport of Air Pollutants by Connective Clouds, Part III: Transport Features of Different Cloud Systems
Kong Fanyou, Qin Yu
1994, 11(1): 13-26. doi: 10.1007/BF02656989
The vertical transport features of gaseous pollutants, with a negative exponent profile of concentration, by dif-ferent types of convective cloud systems are numerically investigated by using a two-dimensional, reactionless convective cloud transport model. The results show that an isolated, weak storm is able to pump pollutant gas out PBL and transport it to the mid-troposphere, whereas a deep, intense thunderstorm can very efficiently transport air pollutants up to the mid and upper troposphere and laterally spread with anvil, forming an extensive concentration surge layer at altitude of ten-odd kilometers altitude. Each type of convective transport results in concentration re-duction in PBL. In a wind shear environment the transport efficiency of deep thunderstorm significantly increases and the pollutants enter into clouds on the downshear side at low-level and spread downwind in anvil layer. On the other hand, for a cumulus cloud with plenty of liquid water, the gas dissolution effect is increased, and the irreversible aqueous reactions, in extreme, may significantly weaken the vertical transports of pollutant gases even with solubility coefficients no more than 103 M atm-1.
Study on Atmospheric Ozone in East Asia with Satellite Observation
Zhao Bolin, Li Wanbiao, Zhu Yuanjing
1994, 11(1): 27-35. doi: 10.1007/BF02656990
The atmospheric ozone in East Asia has been studied with satellite remote sensing. The relationship between at-mospheric ozone and tropopause height is analyzed and its response to weather processes has been discussed. The mean deviation between the total atmospheric ozone content derived from TOVS data and that got from ground-based Dobson spectrophotometer observation is 3.67%. The total atmospheric ozone content increases with the latitude increasing in East Asia. The correlation coefficient between total ozone content and tropopause height is negative. The average is 74%. The total atmospheric ozone content is closely related to weather processes. Ozone con-tent increases while arctic air mass invading and decreases while tropic air mass coming.
Arnol’d’s Second Nonlinear Stability Theorem for General Multilayer Quasi-geostrophic Model
Liu Yongming, Mu Mu
1994, 11(1): 36-42. doi: 10.1007/BF02656991
Arnol’d’s second nonlinear stability criterion for motions governed by a general multilayer quasi-geostiophic model is established. The model allows arbitrary density jumps and layer thickness, and at the top and the bottom of the fluid, the boundary condition is either free or rigid. The criterion is obtained by the establishment of the upper bounds of disturbance energy and potential enstrophy in terms of the initial disturbance field.
Vertical Structure of Beta Gyres and Its Effect on Tropical Cyclone Motion
Tian Yongxiang, Luo Zhexian
1994, 11(1): 43-50. doi: 10.1007/BF02656992
Recently, Fiorino and Elsberry (1989) proposed a concept on beta gyres using a numerical model in a quasi-geostrophic barotropic framework, and analysed the horizontal structure. In this paper, the authors extend the findings of Fiorino et al. to a baroclinic atmosphere applying a quasi-geostrophic, three-layer model, and analyse the horizontal and vertical structures of beta gyres and their relation to tropical cyclone motion.
A GCM Study on the Mechanism of Seasonal Abrupt Changes
Wang Huijun, Zeng Qingcun
1994, 11(1): 51-56. doi: 10.1007/BF02656993
In this paper the observational studies and some related dynamical and numerical researches on seasonal abrupt changes were reviewed first. Then a speculation that the seasonal variation of insolation and the nonlinear dynamic interaction account for the abrupt changes was put forward and was asserted by a set of GCM sensitivity experiments. The results show that the abrupt changes would exist in case that all the earth surface was grass land and there was no topography. However, many factors may have influences on the abrupt changes. Hence this phenome-non is quite complicated and needs further investigations.
On Mechanisms of Nucleation of Ice Crystals by Aerodynamic Cooling
Huang Shihong, Qian Changguo, Wang Weimin, Li Ruxiang
1994, 11(1): 57-64. doi: 10.1007/BF02656994
The investigation of mechanisms of nucleation of ice crystals by aerodynamic cooling produced by supersonic airflow is carried out. Three processes are considered to be the principal causes for aerodynamic cooling and nucleation of ice crystals. They are: adiabatic cooling in supersonic airflow, cooling at the cores of vortices around the edge of airflow and entrapment of ambient stationary air into supersonic airflow. It is thermodynamically confirmed that the temperature lowering in supersonic flow depends on the Mach number M there and stagnant pressure Po at a certain stagnant temperature To. The temperature will decrease by more than 6oC as M increases by 0.1. The influence of Po on cooling is shown through the variation of mass flow rates, which increase with Po.Experiments in laboratory have shown that ice-forming rate produced by supersonic airflow increases from 1011 to 1012 /g as M increases from 1.10 to 1.84 at Po= 5 and 6 atm, and increases from 4.3 × 1011 to 10.3 × 1012 /g as the mass flow rate increases from 3.5 to 5.7 g / s and increases from 1.5 to 5.0 atm at M = 1.80 and To= 25oC. In field experiments the ice concentrations of 50 to 200 per liter in about 2000 m3 were measured when air of about 0.5 g were spurted at a Mach number of M = 1.8 into supercooled fog with temperatures between -0.5oC and -4.6oC. These results are compatible with the prediction of aerodynamics.The snapshot taken in experiments represents the detailed structures of vortex motion around a supersonic airflow.
Oscillatory Rossby Solitary Waves in the Atmosphere
Chen Zhongming, Liu Fuming, Li Xiaoping, Tao Jie
1994, 11(1): 65-73. doi: 10.1007/BF02656995
The linear Rossby wave frequency expression is expanded at higher accuracy based on the scale difference char?acteristics of atmospheric long waves in the and directions. That the nature of the waves represented by the expan?sion is identical to that of the original ones is demonstrated both in phase velocity and wave energy dispersion speed , followed by the derivation of the nonlinear expression describing atmospheric long wave behaviors with the associated approximate analytic solution obtained. Then, for the first time atmospheric’ oscillatory Rossby solitary wave’ with its dispersion relation is obtained by numerical calculation with the aid of physical parameters of the real atmosphere. The solitary wave is found to be very close to such longwave systems as blocking highs and cut-off de?pressions in the actual atmosphere.
Note on the Symmetric Stability of Quasi-Homogeneous and Incompressible Rotating Ocean
Ren Shuzhan
1994, 11(1): 74-78. doi: 10.1007/BF02656996
The general property of zonally symmetric stability of quasi-homogeneous and incompressible rotating ocean can be determined by a nondimensional parameter Rs which is similar to the Richardson number in Howard’s paper. The results indicate that the rotating effect leads to stabilize the basic flows and the horizontal shear effect leads to destabilize the basic flows. In addition, the most unstable growth rate is obtained and the semicircle and semiellipse theorem about the distributions of the unstable phase velocity are given in this paper.
The Analysis on the Features of the Atmospheric Circulation in Preceding Winters for the Summer Drought and Flooding in the Yangtze and Huaihe River Valley
Sun Bomin, Sun Shuqing
1994, 11(1): 79-90. doi: 10.1007/BF02656997
Based on the annual variation of the rainfall departure percentage in summer in the lower-middle reaches of the Yangtze River and the Huaihe River valley, 7 cases for the abnormal drought and flooding summers (the drought years: 1981, 1984, 1985; the flooding years: 1980, 1982, 1983, 1987) are selected, First we analyse the general circula-tion characteristics of the summer drought and flooding, and then the evolution processes of the general circulation patterns from preceding winters to summers are studied. It is found that during the two kinds of preceding winters for the drought and flooding summer, not only the general circulation patterns in the high-mid latitudes, the local Hadley cells in East Asia but also the activities of the cold surge in the lower latitude are different obviously. Spring, especially April, is the turning period of the general circulation in preceding winter for the drought or flooding sum-mer evolution towards opposite direction. Hereafter, the drought or flooding circulation pattern is established and developed.
Nonlinear Ultra-Long Wave and Its Stability
He Jianzhong
1994, 11(1): 91-100. doi: 10.1007/BF02656998
A stability of a nonlinear ultra-long wave and its solution are discussed in this paper by employing Burger model which is subject to heat resource. It is of interest noted that the wave solution can be described by an equation of KDV or MKDV and that conditions for the existence of the solution are related to characteristic divergences. In addi-tion, a wave velocity expression for nonlinear ultra-long waves and some diagnostic correlations among wave parameters have been obtained.
Evaluation of Forecast Performance of an Economical Explicit Time Integration Scheme in a Limited Area Model over Indian Region
A. Bandyopadhyay, S.S. Singh
1994, 11(1): 101-110. doi: 10.1007/BF02656999
An economical explicit scheme of time integration is implemented in a regional model over Indian region to achieve computational economy. The model is also integrated by explicit Leap-Frog Scheme. The performance of economical explicit scheme is evaluated by comparing the forecast results with those produced by leap-frog scheme. The results show that the economical explicit scheme produces more or less similar forecasts as compared to those produced with leap-frog scheme. However, application of the economical explicit scheme saves substantial amount of computer time. The scheme is found nearly four times economical as compared lo explicit leap-frog scheme.
Diurnal Variation of Southwest Monsoon Rainfall at Indian Stations
J.M. Pathan
1994, 11(1): 111-120. doi: 10.1007/BF02657000
The paper presents the patterns of rainfall behavior brought out by the diagrams depicting the diurnal variation of SW monsoon rainfall at selected Indian stations. The stations in different geographical locations are found to ex-hibit different patterns of diurnal variation of rainfall. In general, coastal and island stations show enhanced rainfall from midnight to morning hours and below average rainfall during day time. Many inland stations show rainfall max-imum towards afternoon / evening hours. Some hill stations show the same behavior as inland stations. However, at the heavy rainfall station of Cherrapunjee, the rainfall behavior is similar to that at the coastal stations. Possible phys-ical mechanisms responsible for the diurnal variation of rainfall at stations under different categories, are briefly dis-cussed.Harmonic analysis of hourly SW monsoon rainfall data of 33 stations show that for 19 stations, the first harmonic accounts for more than 50% of the variance of the rainfall series. These consist of (i) inland stations for which the maximum of the first harmonic is reached between 16 hours IST and midnight, and (ii) coastal / island sta-tions for which the maximum is seen between 03 and 07 hours IST. At most of the coastal and island stations, the first harmonic alone accounts for 75% or more of the variance. For the heavy rainfall station of Cherrapunjee, the first harmonic which attains its maximum at 3.8 hours IST (~ 4.4 hours LT), is able to account for 96% of the variance of the rainfall series. It is hoped that the information contained in this paper about the pattern of diurnal modulation of monsoon rainfall may serve as background material to monsoon precipitation climatology.