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1996 Vol. 13, No. 2

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A Coupling Experiment of an Atmosphere and an Ocean Model with a Monthly Anomaly Exchange Schem
Liu Hui, Jin Xiangze, Zhang Xuehong, Wu Guoxiong
1996, 13(2): 133-146. doi: 10.1007/BF02656857
A nine-layer spectral atmospheric general circulation model is coupled to a twenty-layer global oceanic general circulation model with the “prediction-correction” monthly anomaly exchange scheme which has been proposed at the Institute of Atmospheric Physics (IAP). A forty-year integration of the coupled model shows that the CGCM is fairly successful in keeping a reasonable pattern of the modelled SST although most of the Pacific become warmer than those given by the uncoupled ocean model. The model tends to reach a more realistic state than the uncoupled one in terms of downward surface heat flux into ocean particularly in the equatorial Pacific region. Also, the model is capable to simulate interannual variability of sea surface temperature in tropical region.
Sensitivity Study of Nonlocal Turbulence Closure Scheme in Local Circulation
Chen Ming, Hong Zhongxiang, Arnaldo Longhetto, Richiardone Renzo
1996, 13(2): 147-158. doi: 10.1007/BF02656858
In this paper, the Theory of Transient Turbulence (TTT) is applied to a 2-D local circulation model to parameterize the turbulent transport processes. Our purpose is to test the efficiency of TTT in higher dimensional model and the sensitivity of simulated results to the TTT parameters. The results show that under near-neutral and unstable situations the TTT is feasible, but the mean field and the turbulence field may hive different sensitivities to the parameters. Some modification should be given to the magnitudes of parameters suggested Stull and Driedonks (1987) for different background fields and numerical grid spaces.
Model for Methane Emission from Rice Fields and Its Application in Southern China
Ding Aiju, Wang Mingxing
1996, 13(2): 159-168. doi: 10.1007/BF02656859
A process model has been developed. The model has been used to calculate the methane emission from rice fields. The influence of climate conditions, field water management, organic fertilizers and soil types on methane emission from rice fields are considered. There are three major segments which are highly interactive in nature in the model: rice growth, decomposition of soil organic matter and methane production, transport efficiency and methane emission rate. Explicit equations for modeling each segment mentioned above are given. The main results of the model are: 1. The seasonal variation of methane emission of the model output agrees with that of field experiments. The de-viation of seasonal average methane emission rate between modeled value and experimental data is about 10%. 2. In the whole rice growing period, model output is similar to experimental data in the seasonal variation of transport ability of rice plant. 3. Soil organic matter content and soil physics and chemistry are major factors that determine the total season average emission rate, while soil temperature controls the temporal variation of methane emission from rice fields.
A 2-D Non-local Closure Model for Atmospheric Boundary Layer Simulations
Jiang Weimei, Wang Xuemei
1996, 13(2): 169-182. doi: 10.1007/BF02656860
In this paper a new approach for PBL simulation, the non-local closure scheme based on the transient turbu-lence theory has been used. It was set up as an alternative to local closure schemes which physical concept is reasona-ble and distinct. A 2-D non-local closure model was developed in order to study the PBL structure and simulate some interesting atmospheric processes over non-uniform underlying surface, especially under the convective and unique weather conditions, such as sea-land circulation and the TIBL structure. The modelled results show good agreement with field measurement.
Behaviour of Coupled Modes in a Simple Nonlinear Air-Sea Interaction Model
Li Chongyin, Liao Qinghai
1996, 13(2): 183-195. doi: 10.1007/BF02656861
In this article, a model with the simplest framework is constructed and solved analytically. It is shown that intrasensonal wave coexists with interannual variation, and ENSO cycle arises from coupled Kelvin wave destabilisation. Its irregularity can be related to reasonable model parameters. External processes have some impor?tant effects on nonlinear air-sea interaction modes.
Impacts of the Kuwait Oil Fires on the Mount Qomolangma Region
Gao Dengyi, Lu Weixiu, Gao Yongqi
1996, 13(2): 196-202. doi: 10.1007/BF02656862
Mt. Qomolangma (also known as Mt. Everest), the world’s highest mountain, is situated over the world’s highest plateau, the Tibetan Plateau. Because of its height and because of its distance from industrialized areas, the environmental state of the Mt. Qomolangma region can normally be considered “undisturbed”. It is interesting to investigate how this “undisturbed” state has been changing with time and whether it has been influenced by large environmentally disruptive events such as the Kuwait oil fires of 1990 and 1991 (Small, 1991). In order to do this, riv-er water samples were collected from the Rongpu River at Rongpu Temple Station in the summers of 1992 and 1993, as was done in 1975, and aerosol samples were collected in the summer of 1992 at the same station as was done in 1980. River water samples were analyzed using atomic absorption spectroscopy (AAS) at the Chinese Academy of Sciences. Aerosol samples were analyzed using proton-induced x-ray emission (PIXE) at the University of Fudan in Shanghai. The results show that the concentrations of chemical species in the river water at Rongpu Temple Station were much higher in the summer of 1992 than they were in 1975 and 1993, and the concentrations of atmospheric chemical species were much higher in 1992 than they were in 1980. The environment of the north slope of Mt. Qomolangma was therefore heavily polluted before and/or during the summer of 1992, possibly due to the Kuwait oil fires in 1990 and 1991.
On the Nonlinear Stability of Three-Dimensional Quasigeostrophic Motions in Spherical Geometry
Li Yang, Mu Mu
1996, 13(2): 203-216. doi: 10.1007/BF02656863
Nonlinear Mobility criteria for the motions geoverned by three-dimensional quasigeostrophic model in spherical geometry are obtained by using Arnol’d’s variational principle and a priori estimate method. The results gained in this paper are parallel to Arnol’d’s second theorem and better than the known results. Especially, under the approxima-tion of vertically integrated nondivergency, criteria corresponding to Arnol’d’s second theorem are first established by a detailed analysis.
Influence of Clouds on UV Irradiance at Ground Level and Backscattered Exittance
Wang Pucai, Jacqueline Lenoble
1996, 13(2): 217-228. doi: 10.1007/BF02656864
The influence of various cloud parameters and the interactions with the ground albedo and the solar zenith angle have been studied by means of model simulations. The radiative transfer model suitable for a cloudy atmosphere as well as for a clear atmosphere has been developed on the basis of the Discrete Ordinate Method. This study leads to a general understanding for cloudy atmospheres: in the presence of a uniform cloud, the cloud scattering is dominant to molecular and aerosol scattering, and it is also wavelength-independent; the ratio of transmitted irradiance in a cloudy atmosphere to that in the background clear atmosphere is independent of cloud height and solar zenith angle. That’s to say, the radiation downwelling out of a cloud is quite isotropic; it decreases approximately exponentially with the cloud optical depth at a rate related to the ground albedo; the reflected irradiance at the top of the atmosphere is dependent on cloud optical depth as well as on solar zenith angle, but not on ground albedo for clouds of not very thin optical depth.
Comparison of Surface Wind Stress Anomalies over the Tropical Pacific Simulated by an AGCM and by a Simple Atmospheric Model
Ni Yunqi, S. E. Zebiak, M. A. Cane, D. M. Straus
1996, 13(2): 229-243. doi: 10.1007/BF02656865
In this paper, surface wind stress anomalies over the tropical Pacific simulated by an AGCM and by a simple at-mospheric model are compared with observed. The AGCM is the higher resolution global spectral model-COLA R40 model and the simple atmospheric model is the atmospheric component of the Cane-Zebiak coupled ocean-at-mosphere model The results show that the wind stress anomalies simulated by both the COLA R40 and the simple model have captured the main features of observation but the x component in the CZ model is closer to that in observation than that in the COLA model, and the correlation coefficients between simulated SSTA from the CZ model and observed for Nino indices are higher than those from the COLA model.
Some Possible Solutions of Nonlinear Internal Inertial Gravity Wave Equations in the Atmosphere
Li Guoping, Lu Jinghua
1996, 13(2): 244-252. doi: 10.1007/BF02656866
In this paper, the nonlinear internal inertial gravity wave equation is derived by the analysis method of phase plane and is solved by integration method. The results showed that this nonlinear equation not only has ordinary soli-tary wave solution but also has another extra-ordinary solutions, and the form of solution is related to stratification stability, wave velocity and direction of wave motion.
Effects of Land-Sea Distribution, Topography and Diurnal Change on Summer Monsoon Modeling
Wang Qianqian, Qian Yongfu
1996, 13(2): 253-259. doi: 10.1007/BF02656867
The effects of the land-sea distribution, the topography and the diurnal change of the solar radiation on the summer monsoon modelings are studied by use of a coupled modeling system with a 5-layer primitive equation mod-el of the atmosphere and a 2-layer soil or ocean thermodynamic model which are all solved in a zonal model domain between 60o S and 60oN. The results of numerical simulations show that the quasi-stationary patterns of the mean monsoon circulations are mainly affected by the land-sea distribution and the topography, the effect of the diurnal change is the secondary. However, the inclusion of the diurnal change into the model system may improve the intensi-ty of the simulated monsoon circulation, it can influence the distributive pattern of precipitation to a larger extent, without the diurnal change precipitation in the interior of land would decrease and in the coastal regions it would increase.
The East Asian Monsoon Simulation with IAP AGCMs-A Composite Study
Wang Huijun, Bi Xunqiang
1996, 13(2): 260-264. doi: 10.1007/BF02656868
Preliminary analyses on simulation of East Asian monsoon (EAM) by IAP 9-level and 2-level Atmospheric General Circulation Models of AMIP run were made. The analyses include the seasonal and interannual variations of EAM circulation, the monsoon index defined with 850 hPa wind, the circulation differences of composite strong and weak monsoon years and the regional precipitation over China monsoon region. Two models can give reasonable simulation on the seasonal variation of the subtropical high over Western Pacific and the middle latitude circulation index, the observed global circulation differences for strong and weak EAM. However, the abilities of the models on reproducing the cross-equatorial wind of EAM system, the interannual variation of EAM and the regional precipitation variability are unsatisfactory. Improvements on EAM simulation should contain both the better representation on the regional surface details (orography surface albedo and surface water and energy flux) and the improvement of the tropical global circulation, modelling.
Studies on Non-interpolating Semi-Lagrangian Scheme and Numerical Solution to KdV Equation
Chen Jiabin, Wang Jun
1996, 13(2): 265-268. doi: 10.1007/BF02656869
A new non-interpolating semi-Lagrangian scheme has been proposed, which can eliminate any interpolation, and consequently numerical smoothing of forecast fields. Here the new scheme is applied to KdV equation and its performance is assessed by comparing the numerical results with those produced by Ritchie’s scheme (1986). The comparison shows that the non-interpolating semi-Lagrangian scheme appears to have efficiency advantages.