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1990 Vol. 7, No. 2

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Correlations between Sea Surface Temperature in Eastern Equatorial Pacific and Rain Days over China in Summer
Huang Jiayou
1990, 7(2): 127-136. doi: 10.1007/BF02919150
Sea-surface temperature (SST) in the eastern, equatorial Pacific and rain days over China in summer are ana-lysed using correlation moments, that is proposed by author and principal component analysis (PCA). Occurrences of the strong rain-day anomalies over China are associated with extreme SSTs in some years. Areas significantly affect-ed by the phenomena include North and Northeast China.
An Exact Solution for Two-Dimensional Frictionless Motion in the Atmosphere
S. Panchev
1990, 7(2): 137-141. doi: 10.1007/BF02919151
A solution of the nonlinear problem for determining the wind velocity in frictionless atmosphere (the gradient wind) under given geopotential (pressure) field is proposed. The approach is analytical and is based on quadratic polynomial approximation of the geopotential field and linear approximation of the wind velocity field with respect to x and y, the coefficients of the expansions being functions of the time t. The derived system of ordinary nonlinear differential equations is analyzed as a dynamical system. Exact analytical solutions are found for some par-ticular cases, Some of their properties bear a resemblance to those or really existing atmospheric vortices (cyclones and anticyclones).
Development and Test of Hydrostatic Extraction Scheme in Spectral Model
Zhang Daomin, Sheng Hua, Ji Liren
1990, 7(2): 142-153. doi: 10.1007/BF02919152
The introduction of “hydrostatic extraction” scheme, or “standard stratification approximation”, into spectral model gained some advantages compared with commonly used schemes. However, computational instability may oc-cur for high vertical resolution versions if the stratification parameter C0 taken as a constant. In this paper, the pos-sible cause leading to the instability is discussed and an improved scheme presented where C0 is generalized to be a function of both height and latitudes. Hence the reference atmosphere gets closer to the real atmosphere and the tem-perature deviation field to be expanded becomes smoother everywhere. Test by real case forecasts shows good computational stability of the new scheme and better prediction performance than usual schemes of spectral model.
Numerical Simulation of Microphysics in Meso-β-Scale Convective Cloud System Associated with a Mesoscale Convective Complex
Fan Beifen, Ye Jiadong, William R. Cotton, Gregory J. Tripoli
1990, 7(2): 154-170. doi: 10.1007/BF02919153
Numerical simulation of meso-β-scale convective cloud systems associated with a PRE-STORM MCC case has been carried out using a 2-D version of the CSU Regional Atmospheric Modeling System (RAMS) nonhydrostatic model with parameterized microphysics. It is found that the predicted meso-γ-scale convective phenomena are basically unsteady under the situation of strong shear at low-levels, white the meso-β-scale convective system is maintained up to 3 hours or more. The meso-β-scale cloud system exhibits characteristics of a multi-celled convective storm in which the meso-γ-scale convective cells have lifetime of about 30 min. Pressure perturbation depicts a meso-low after a half hour in the low levels. As the cloud system evolves, the meso-low inten-sifies and extends to the upshear side and covers the entire domain in the mid-lower levels with the peak values of 5-8 hPa. Temperature perturbation depicts a warm region in the middle levels through the entire simulation period. The meso-γ-scale warm cores with peak values of 4-8oC are associated with strong convective cells. The cloud top evapo-ration causes a stronger cold layer around the cloud top levels.Simulation of microphysics exhibits that graupel is primarily concentrated in the strong convective cells forming the main source of convective rainfall after one hour of simulation time. Aggregates are mainly located in the stratiform region and decaying convective cells which produce the stratiform rainfall. Riming of the ice crystals is the predominant precipitation formation mechanism in the convection region, whereas aggregation of ice crystals is the predominant one in the stratiform region, which is consistent with observations. Sensitivity experiments of ice-phase microphysical processes show that the microphysical structures of the convective cloud system can be simulated better with the diagnosed aggregation collection efficiencies.
Association among Geomagnetic Activity, Atmospheric Electric Field and Selected Meteorological Parameters
Poonam Mehra
1990, 7(2): 171-177. doi: 10.1007/BF02919154
The association among the geomagnetic activity (Ap index) and atmospheric electric field, meteorological parameters was investigated using a long series of continuous data set available for Colaba (18o53’N, 72o48’E, 11m ASL) for the period 1936-1966. The meteorological parameters used for the investigation are the surface pressure, temperature, wind velocity and relative humidity. The results of the above study indicate that the atmospheric electric field and the meteorological parameters are associated with the geomagnetic storms with Ap > 100. The atmospheric electric field shows an increasing trend after the geomagnetic storm. The surface pressure dips and surface tempera-tures increase after a geomagnetic storm. The wind velocity shows a decreasing trend and the relative humidity shows an increasing trend after the geomagnetic storm.
A Study of Suspended Participate Matter in Lahore (Pakistan)
K. Hussain, Ruby Riffat, A. Shaukat, M. Ashraf Siddiqui
1990, 7(2): 178-185. doi: 10.1007/BF02919155
The results obtained from an investigation of suspended particulate matter in the metropolitan city of Lahore (Pakistan) are reported and analysed in this paper. X-ray diffraction studies of the airborne matter collected from va-rious urban and suburban sites show that non-clay minerals such as quartz, calcite and albite are contained in most of the samples in almost comparable amounts. Chemical analysis of some samples was carried out for complementing the x-ray diffraction data. The amount of quartz in the samples of dusty areas was found to be an order of magnitude more than in the samples of relatively cleaner areas. As the dust particles of these compounds are poor substrate for promoting nucleation of ice in the atmospheric clouds, they are liable to stay steadily in the atmosphere as pollutants.A comparison of the results of the airborne particulates and the soil samples collected from various sites show that the sources of quartz, calcite and albite in the airborne matter are both local and remote.
Introduction of the Direct Method by Illustrating Schr?dinger Equation and Its Application to Wave-Wave Striking Interaction
Gao Shouting, Liu Kunru
1990, 7(2): 186-191. doi: 10.1007/BF02919156
In this paper, both direct method and its application to wave-wave striking interaction are introduced by illus-trating Schr?dinger equation describing the amplitude evolution of some mesoscale systems.
The Ozone, Aerosol Depletion and Condensation Nuclei Events in the Stratosphere
Venkat NR. Mukku
1990, 7(2): 192-196. doi: 10.1007/BF02919157
Recently, the depletion in ozone and aerosol extinctions inside Antarctic Spring westerly vortex and condensa-tion nuclei enhancement events in the mid latitudes stratosphere were related to downward transport of aerosols by subsidence and sedimentation. However, the problems associated with such hypothesis would keep a constraint on photochemical theories on ozone hole and stratospheric condensation nuclei (CN) events. Alternately, the gross fea-tures of aerosol hole are better explicable assuming a reversed residual circulation. This opens a path for combined operation on ozone by both photochemistry and dynamics in the same space domain.Independently, we relate the CN events to the growth and transport of negative ion complexes above the Peak of Junge Layer (PJL) without invoking photochemistry in order to be consistant with the observed interhemispheric dif-ferences in the planetary wave activity and CN concentration.
A Coupled Dynamical-Radiational Model of Stratocumulus
Ye Weizuo
1990, 7(2): 197-210. doi: 10.1007/BF02919158
A model dealing with interactions between the air and low stratiform clouds is presented based on the mixed-Layer model Lilly (1968) pioneered and on Deardorff’s three dimensional numerical model results. Its main new aspects lie in 1) consideration of the natures of both the atmosphere and cloud; 2) a new entrainment velocity scheme with few arbitrary assumptions; 3) transition from one-mixed layer to two-mixed layer model; and 4) parameterization of radiation and precipitation calculations.The model results for radiation, moisture, and heat turbulent fluxes turn out to be in good agreement with those calculated or observed by Kawa (1988). Nicholls (1984), and Schmets et al. (1981) in California, the North Sea, and the North Atlantic, respectively.Basically, this paper furnishes the theoretical basis for a model to address questions concerning the time-evolu-tion of thermodynamical profiles both in cloud and out of cloud. The applications of this model will be in a separate paper.
The Study of In-Orbit Calibration Accuracy of NOAA Satellite Infrared Sounder and Its Effect on Temperature Profile Retrievals
Dong Chaohua, Liu Quanhua, Li Guangqing, Zhang Fengying
1990, 7(2): 211-219. doi: 10.1007/BF02919159
The calibration accuracy of High Resolution Infrared Radiation Sounder Mod. 2 (H1RS / 2) on NOAA-10 sat-ellite is analyzed in this paper. The non-linear effect in the linear calibration curve induces a deviation of 1.5 degrees (k) of brightness temperature in the tenth channel (8.3 urn, water vapor absorption) of the HIRS / 2 and the non-linear effect affects the other channels to a different extent. Based on analyzing non-linearity in two-point calibration curve, a tri-point calibration equation is given. A numerical test of effects of the linear and non-linear calibration models on the accuracy of atmospheric temperature retrievals is carried out.
Analysis and Study of a Mesoscale Inertia-Gravitational Wave in Upper Air
Zhang Ying, Shen Xinyong, Zhang Ming
1990, 7(2): 220-226. doi: 10.1007/BF02919160
A mesoscale inertia-gravitational wave at 200 hPa is analysed. The reasons of this wave occurring are also dis-cussed. It is indicated that the occurrence of this wave is due to inertia-gravitational instability, and closely related to horizontal and vertical shear of wind.
Advances in Studies on Nonlinear Atmospheric Waves
Liu Shida, Liu Shikuo
1990, 7(2): 227-244. doi: 10.1007/BF02919161
A review on the progress in the research of nonlinear atmospheric waves, especially the nonlinear Rossby waves is made in this paper. Many results reported here have been obtained in Peking University.
Global Annual Mean Surface Air Temperature Anomalies and Their Link with Indian Summer Monsoon Failures
S. S. Dugam, S. B. Kakade, R. K. Verma
1990, 7(2): 245-248. doi: 10.1007/BF02919162
Analysis of the global mean annual temperature anomalies based on land and marine data for the last 88 years (1901-1988) of this century has been carried out with a view to find any relationship with failures in Indian summer monsoon rainfall. On the climatological scale (i.e. 30 years) it has been noticed that there is as abnormal increase in the frequency of drought years during epochs of global warming and cooling, while it is considerably less when global temperatures are near normal. Results are unchanged even when the data are filtered out for ENSO (El-Nino South-ern Oscillation) effect.It has also been noticed that during warm and cold epochs in global temperatures the amount of summer mon-soon rainfall decreases as compared to the rainfall during a normal temperature epoch.