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1987 Vol. 4, No. 2

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EQUATORIAL SOLITARY WAVES OF TROPICAL ATMOSPHERIC MOTION IN SHEAR FLOW
Li Maicun
1987, 4(2): 125-136. doi: 10.1007/BF02677059
Abstract:
Starting from the primary equations, the author derives the KdV equation which describes solitary Rossby waves in the tropical atmosphere, and indicates that, because these waves are ageostrophic, they differ from the quasigeostrophic solitary Rossby waves studied by Redekopp et al. Owing to nonlinear action, these waves are also different from traditional linear waves of the tropical atmosphere. The author believes that the stationary tropical atmospheric waves reflect the characteristics of solitary waves in that the energy does not disperse.
ABRUPT CHANGE OF FLOW PATTERN IN BAROCLINIC ATMOSPHERE FORCED BY JOINT EFFECTS OF DIABATIC HEATING AND OROGRAPHY
Luo Zhexian
1987, 4(2): 137-144. doi: 10.1007/BF02677060
Abstract:
Based on the catastrophic theory, the possible causes of abrupt change in the atmospheric circulation over the Northern Hemisphere during June and October have been explored by Li and Luo (1983) and Miao and Ding (1933). However these studies are confined to the baroiropic atmosphere without consideration of orography. The purpose of this paper is to further study the physical mechanism of the abrupt change of flow pattern within the baroclinic atmosphere in the presence of orography. Results show that the abrupt change of flow pattern can be stimulated by the gradual variation of a diabaticaily heating parameter, which is similar to the observed fact about the rapid shift of position of the subtropical high center in the upper troposphere along the zonal direction during seasonal transition from the summer half year to the winter one.
THE SENSITIVITY OF THE NUMERICAL SIMULATION TO OROGRAPHY SPECIFICATION IN THE LOWRESOLUTION SPECTRAL MODEL-PART II: IMPACT OF THE SMOOTHED OROGRAPHY AND RIPPLES ON SIMULATIONS
Ni Yunqi, Bette L. Otto-Bliesner, David D. Houghton
1987, 4(2): 145-155. doi: 10.1007/BF02677061
Abstract:
In order to investigate the impact of the smoothed orography and the spurious orographic ripples on simu-lations in the low-resolution spectral model, three different numerical tests, that is, the unsmoothed orography scheme, the smoothed orography scheme and non-ripples scheme are performed. In this paper, the model used by us is the same as Part I except for orographic specification.The results from simulations indicate that, as far as the climatic simulation is concerned, some aspects of the simulated stationary disturbances, zonal and meridional wind, temperature and precipitation in the low-resolu-tion spectral model with properly smoothed mountains are significantly improved, especially in winter hemis-phere.The deep ripples in the model with the unsmoothed orography produce spurious high pressure regions at the surface with subsidence, and suppress rainfall, causing an unrealistic splitting of the precipitation area in northern winter and summer. Removal of tbe deep ripples by using the special procedure for smoothing topog-raphy allows a strong upward motion in the ripple area with heavy rainfall, eliminating the unrelistic split in the precipitation area.
DESIGN AND TEST OF AN IMPROVED SCHEME FOR GLOBAL SPECTRAL MODEL WITH REDUCED TRUNCATION ERROR
Chen Jiabin, Ji Liren, Wu Wanli
1987, 4(2): 156-168. doi: 10.1007/BF02677062
Abstract:
An improved scheme of spectral model has been investigated in this paper. Through the introduction of a reference atmosphere, prognostic variables become smoother on the tilled sigma-surface over mountains or a frontal zone, and thus truncation errors are reduced. As a result, the problems about Gibbs waves and negative value of model topography on the sea, which are encountered in the current spectral model in the world, can be solved by the improved scheme. For comparison we have performed the numerical integrations of barotropic and baroclinic Rossby-Haurwitz waves, as well as the prediction of real cases with the improved scheme and the current scheme of spectral model. These results show that the scheme presented in the paper is better than the current scheme of spectral model.
RELATIONSHIPS OF SOUTHERN-OSCILLATION AND OTHER LARGE-SCALE FEATURES WITH BAY OF BENGAL CYCLONES DURING THE POST-MONSOON SEASON
S. V. Singh, C.M. Mohile, S. R. Inamdar
1987, 4(2): 169-174. doi: 10.1007/BF02677063
Abstract:
Relationships of three Southern Oscillations and a few other large-scale atmospheric indices, like Stratos-pheric Quasi-Biennial Oscillation, Northern Hemispheric surface air temperature, 50 hPa subtropical ridge po-sition, Indian monsoon rainfall, with the movement and formation of the tropical cyclones over the Bay of Ben-gal during the post-monsoon season are examined. In general, these relationships are not very satisfactory. However, there is some indication that the low phase of the Southern Oscillation is associated with lower mean latitude of the track of cyclones.
THE INTERFACE EFFECT AND THE FORMATION OF A LOW-LEVEL JET ALONG THE EAST SIDE OF THE ROCKY MOUNTAINS
Zhou Jun, Walter K. Henry
1987, 4(2): 175-184. doi: 10.1007/BF02677064
Abstract:
Based upon the analysis of several different causes for the low-level jet along the east side of the Rocky Moun-tains, the concept of “Interface Effect” is established. The basic mechanism for the formation of the low-level jet in North America has been found to be the compression and divergence, under the driving of ageostrophic winds, of the air columns between two surfaces-the ground and the bottom of inversion-which slope with different patterns in a cross-section normal to the jet stream. As a result, the air parcel is accelerated along the stream-line and the anticyclonic shear of the current increased. Also, the diurnal variation of the jet is determined by the interface effect.
ANALYSIS OF THE TELECONNECTIONAL STRUCTURES OF THE 500-hPa HEIGHT FIELD OVER THE NH IN JANUARY
Wang Panxing, Gao Zhi, Li Changqing
1987, 4(2): 185-197. doi: 10.1007/BF02677065
Abstract:
Based on the oblique mode scheme provided in the Appendix, and analysis is made of the teleconnectional structures (TNS) of the NH 500-hPa height field in January, resulting in a series of teleconnectional patterns re-presentative of the main features of TNS, of which the teleconnectional pattern WPAA (Western Pacific/Asian/ American) closely related to the East-Asian circulation is presented for the first time in this field of research. Contrast analysis indicates that TNS are so sensitive to the transition of seasons that a slight transition would bring about a considerable response. Hence the examination of the month-to-month TNS of the NH atmospher-ic circulations is indispensable.
NUMERICAL STUDY OF LAKE-LAND BREEZE OVER LAKE V?TTERN SWEDEN
Wu Zengmao
1987, 4(2): 198-209. doi: 10.1007/BF02677066
Abstract:
This paper describes a two-dimensional lake breeze model with turbulent energy closure. The simulated results show that (1) the front of the lake breeze progresses inland faster in the late afternoon than at the fully developed stage; and (2) the lake breeze and land breeze have larger extension offshore than inland. The acce-leration of the front in the declining phase of the lake breeze is explained in terms of the decreased turbulent fric-tion acting on the head of the lake breeze. The larger extension offshore, probably, is attributed to the smaller roughness of water surface and to the offshore synoptic wind.
THE ABNORMAL PERIODS OF CLIMATE IN CHINA OVER THE PAST 5000 YEARS AND THEIR CAUSES
Ren Zhenqiu
1987, 4(2): 210-217. doi: 10.1007/BF02677067
Abstract:
This paper points out that (1) there were 5 abnormal periods of climate in China over the last 1000 years, in which the frequency, the severity and the influenced area of such calamities as low temperature, drought and flood increased greatly; (2) there were 3 or 4 worse periods of climate over the past 5000 years which were more severe than the above-mentioned climate; (3) the momental effect of the geocentric synods of nine plan-ets is one of the important causes for the formation of the abnormal and worse periods of climate; and (4) from the 1960s to about 2000 A.D. China and the entire Northern Hemisphere would probably undergo another ab-normal period of climate.
A STUDY ON NO AND NO2 ABSORPTION PROPERTIES BY USING LINE-TUNABLE CO LASER
Wang Gengchen, Kong Qinxin
1987, 4(2): 218-224. doi: 10.1007/BF02677068
Abstract:
The absorption properties of NO in 5.2 μm band and NO2 in 6.2 μm band are measured for some definite wavelengths by using line-tunable CO laser and long-path absorption cell. The absorption coefficients for 49 CO laser wavelengths are given and variations of absorption withpartial and total pressures are analysed. Fur-thermore, the experimental errors and the interference of water vapour with the absorption at definite laser lines are also discussed.
PRIMARY STUDY OF SULFATE AND CARBONACEOUS AEROSOLS IN BEIJING
Su Weihan, Zhang Qiupeng, Song Wenzhi, R. L. Dod, R. D. Giauque, T. Novakov
1987, 4(2): 225-232. doi: 10.1007/BF02677069
Abstract:
Results of our aerosol study, performed during 1983-1984 in Beijing, demonstrate that ambient carbonaceous aerosols are derived mainly from coal combustion. Different SO2 oxidation processes have been observed in summer and winter. The winter sulfate appears to be produced locally and associated with products of incom-plete combustion.
ON THE PARAMETERIZATION OF THE VERTICAL VELOCITY AT THE TOP OF PLANETARY BOUNDARY LAYER
Zhao Ming
1987, 4(2): 233-239. doi: 10.1007/BF02677070
Abstract:
In this paper, an equation of the vertical velocity at the top of PBL is derived by use of a PBL model which is based on an analytic and actual form of K. Results show that the vertical velocity is a function of geostrophic vorticity, geostrophic wind speed, Coriolis parameter and the roughness of the ground, thus improving Charney-Eliassen’s formula. The order of magnitude of the vertical velocity computed from our equation is in agreement with that from the latter, but more factors affecting the vertical velocity are included.
A NUMERICAL SIMULATION OF FLOW AND CONCENTRATION FIELDS ON MOUNTAIN LEE-SIDE
Sang Jianguo, Wu Gang
1987, 4(2): 240-247. doi: 10.1007/BF02677071
Abstract:
In the present paper the numerical integration of the atmospheric thermodynamic equation system is carried out to simulate the flow and concentration fields over a two-dimensional mountain. The concentration distri-butions from a continuous elevated release point at different positions on the lee-side under a variety of atmos-pheric stabilities are calculated to examine the effects of topography on the diffusion of pollutants. The comparison between the results calculated by the model and those observed in field experiments indicates that the model can predict the transport and diffusion of pollutants under different atmospheric conditions over complex terrain and may become an applicable tool for solving the air quality problems in mountain areas.