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1993 Vol. 10, No. 4

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Meteorological Satellite TIROS-N TOVS Remote Sensing of Atmospheric Property and Cloud
Zhao Bolin, Zhu Yuanjing, Zhang Chengxiang, Zhen Jinming, Zhang WenJan
1993, 10(4): 387-392. doi: 10.1007/BF02656963
In this paper, a new retrieval method, i.e., the Statistical-Physical Retrieval Method (STPRM) has been devel-oped. It is a combination of both statistical and physical method. On this basis, a retrieval system of temperature-humidity profiles and cloud parameters has been developed. By use of the developed TOVS STPRM the distribution of atmospheric temperature, humidity and geopotential height on isobaric surface can be obtained, in companion with the statistical method and physical method, the TOVS STPRM system not only has the advantage of convenience in use, quickness in data processing and accuracy in retrieval result, but also can display cloud evolu-tion on screen.
Group Velocity of Anisotropic Waves-Part I: Mathematical Expression
Yong L. McHall
1993, 10(4): 393-406. doi: 10.1007/BF02656964
The group velocity used in meteorology in the last 30 years was derived in terms of conservation of wave energy or crests in wave propagation. The conservation principle is a necessary but not a sufficient condition for deriving the mathematical form of group velocity, because it cannot specify a unique direction in which wave energy or crests propagate. The derived mathematical expression is available only for isotropic waves. But for anisotropic waves, the traditional group velocity may have no a definite direction, because it varies with rotation of coordinates. For these reasons, it cannot be considered as a general expression of group velocity. A ray defined by using this group velocity may not be the trajectory of a reference point in an anisotropic wave train. The more general and precise expression of group velocity which is applicable for both isotropic and anisotropic waves and is independent of coordinates will be derived following the displacement of not only a wave envelope phase but also a wave reference point on the phase.
Group Velocity of Anisotropic Waves-Part II: Conservative Properties
Yong L. McHall
1993, 10(4): 407-414. doi: 10.1007/BF02656965
It has been argued in Part I that traditional expression of multidimensional group velocity used in meteorology is only applicable for isotropic waves. While for anisotropic waves, it cannot manifest propagation of waves group along the trajectory of a reference wave point, and varies with rotation of coordinates. The general mathematical ex-pression of group velocity which may be used also for anisotropic waves has been derived in Part I. It will be proved that the mean wave energy, momentum and wave action density are all conserved as a wave group propagates at the general group velocity. Since general group velocity represents the movement of a reference point in either isotropic or anisotropic wave trains, it may be used to define wave rays. The variations of wave parameters along the rays in a slowly varying environment are represented by ray-tracing equations. Using the general group velocity, we may de-rive the anisotropic ray-tracing equations, which give the traditional ray-tracing equations for isotropic waves.
The Vertical Transport of Air Pollutants by Convective Clouds. Part I: A Non-Reactive Cloud Transport Model
Kong Fanyou, Qin Yu
1993, 10(4): 415-427. doi: 10.1007/BF02656966
A convective cloud transport model, without chemical processes, is developed by joining a set of concentration conservative equations into a two-dimensional, slab-symmetric and fully elastic numerical cloud model, and a nu-merical experiment is completed lo simulate the vertical transport of ground-borne, inert gaseous pollutant by deep thunderstorm. The simulation shows that deep convective storm can very effectively transport high concentrated pollutant gas from PBL upward to the upper troposphere in 30 to 40 minutes, where the pollutant spreads laterally outward with strong anvil outflow, forming an extensive high concentration area. Meanwhile, relatively low concen-tration areas are formed in PBL both below and beside the cloud, mainly caused by dynamic pumping effect and sub-cloud downdraft flow. About 80% of the pollutant gas transported to the upper troposphere is from the layer be-low 1.5 km AGL (ahove ground level).
Diagnostic Study of a Winter Snowstorm Event
Shou Shaowen, Zhu Aimin
1993, 10(4): 428-434. doi: 10.1007/BF02656967
A diagnostic study of a winter snowstorm event was presented. The results showed that some factors were of im-portance to the formation of the snow gush. Most of the factors were similar to those for summer rain gush, while the temperature stratification structure was important to distinguish snow from rain.
Study on Atmospheric Travelling Wave Solutions and Review of Its Present Developments
Huang Sixun, Zhang Ming
1993, 10(4): 435-446. doi: 10.1007/BF02656968
The scientific achievements of travelling waves in a barotropic atmosphere are introduced, including i) the exist-ence conditions of periodic solutions (wavetrain solutions) and solitary wave solutions (pulse solutions), together with the solution finding methods and a series of related problems, ii) seeking solutions of monotonous wave (wave front) and of nonmonotonous travelling wave (oscillatory wave) by using phase plane shooting technique and iii) progress in the study of travelling wave solution at home and abroad. The investigation of travelling wave solutions in recent years has been found in mathematics, physics, chemistry, biology and other sciences. Over the past decade the prob-lem has been the subject of much interest and become an important area of research. So it is no doubt of great signifi-cance to investigate the travelling wave solutions and thereby explain phenomena of weather.
An Improved Splitting Method
Wang Bin, Ji Zhongzhen
1993, 10(4): 447-452. doi: 10.1007/BF02656969
In this paper, an improved splitting method, based on the completely square-conservative explicit difference schemes, is established. Not only can the time-direction precision of this method be higher than that of the traditional splitting methods but also can the physical feature of mutual dependence of the fail and the slow stages that are calcu-lated separately and splittingly be kept as well. Moreover, the method owns an universality, it can be generalized to other square-conservative difference schemes, such as the implicit and complete ones and the explicit and instanta-neous ones. Good time benefits can be acquired when it is applied in the numerical simulations of the monthly mean currents of the South China Sea.
The Relationship between the Wintertime Blocking over Greenland and the Sea Ice Distribution over North Atlantic
Fang Zhifang, John M. Wallace
1993, 10(4): 453-464. doi: 10.1007/BF02656970
The sea-ice concentration in the Northern Hemisphere, 500 hPa height, sea-level pressure and 1000-500 hPa thickness of monthly mean data are examined for the period 1953-1989, with emphasis on the winter season.Relationships between large-scale patterns of atmospheric variability and sea-ice variability are investigated, making use of the correlation method. The analysis is conducted for the Atlantic sectors. In agreement with earlier studies based upon monthly mean data on sea-ice concentration, the strongest sea-ice pattern is composed of a dipole with opposing centers of action in the Davis Straits / Labrador Sea region and the Greenland and Barents Seas. Its temporal variability is strongly coupled to the atmospheric North Atlantic Oscillation (NAO). The relation-ship between the two patterns is strongest with the atmosphere leading the ocean. The polarity of the NAO is associ-ated with Greenland blocking episodes, during which the influence of the atmosphere is strong enough to temporarily halt the climatological mean advance of the ice edge in some regions and substantially accelerate it in others.The relationships between the fields are indicative of local forcing of sea-ice in most regions, with wind stress and thermodynamic fluxes at the air-sea interface both contributing.
Nondispersive Periodic Solution of a Barotropic Semi-Geostrophic Model
He Jianzhong, He Jinhai
1993, 10(4): 465-474. doi: 10.1007/BF02656971
The existence and solution of the non-dispersive periodic solution are achieved concerning nonlinear barotropic Rossby waves of a barotropic semi-geostrophic model, demonstrating the likelihood of the Taylor evolution, togeth-er with the related dimensionless a-criterion. Finally, the wave velocity expression is proposed with some diagnostic relations among the wave parameters.
Convective and Stratiform Cloud Rainfall Estimation from Geostationary Satellite Data
Li Jun, Wang Luyi, Zhou Fengxian
1993, 10(4): 475-480. doi: 10.1007/BF02656972
The Bayes Decision (BD) method was used to distinguish the corrective and stratiform components of cloud sys-tems from GMS-4 satellite data. A technique originally developed by Adler and Negri (1988, hereafter abbreviated AN) was improved for estimating the convective and stratiform cloud precipitation areas and rates of cloud systems from GMS satellite imagery. It has been applied to a tropical cyclonic cloud cluster observed over east coast area of China on September 23, 1992, which brought about flood disaster in that region. Overlaid 6-hour surface rainfall ob-servations show that the rainfall areas and amounts match with results from improved AN technique. The successful application of the Adler and Negri’s technique to convective and stratiform clouds provides encouragement for the use of this method over large region of mid-latitude China where radar data are not fully covered.
On the Spatio-Temporal Variations of the Tropopause Height over India and Indian Summer Monsoon Activity
J.R. Kulkarni, R.K. Verma
1993, 10(4): 481-488. doi: 10.1007/BF02656973
The spatio-temporal variation of the tropopause height (TH) over the Indian region (5°N-35°N, 70°E-95°E) has been studied using monthly mean TH data, for 22-year period, 1965 to 1986. The study revealed that the stations south of 20° showed maximum TH in April / May and minimum in September. This variation in TH has been attributed to the corresponding variation of average sea surface temperature (SST) over ± 20° latitudinal belt over Indian Ocean, Arabian Sea and Bay of Bengal. Further the stations north of 20°N showed maximum in June and minimum in October/ November. This maximum in TH has primarily been attributed to the increased insolation and convection. Furthermore it is noticed that the anomaly of TH moved northwards during the period April to July.The interannual variability of the Indian Summer Monsoon Activity (ISMA) has been studied in relation to all India mean TH (at 12 GMT) for six months April through September. The composites of mean TH for good and bad monsoon years showed that all India mean TH is statistically higher in good monsoon years than in bad monsoon years. The relationship between ISMA and all India mean May TH has been studied using the contingency table. The study suggested that the forecast of ISMA could be prepared using mean May TH.
Studies of Nitrous Oxide Emission from Farmlands in North China
Wang Shaobin, Su Weihan, Song Wenzhi, Zeng Jianghai, Zhang Yuming
1993, 10(4): 489-496. doi: 10.1007/BF02656974
Measurements of nitrous oxide emission from agricultural lands were conducted. The results show that nitrous oxide fluxes on several soils are at the range of 2-60 μg . N / m2 h. Factors influencing the production rates of nitrous oxide from the soils, such as soil temperature, soil moisture and fertilization, are discussed. The calculated amount of nitrous oxide emission from China farmlands is 9.8 × 107 Kg . N per year, which accounts for about 10% of the total source strength in China areas.
Predictability of the 500 hPa Height Field
Chen Yingyi
1993, 10(4): 497-503. doi: 10.1007/BF02656975
The dimensions of attractors and predictability are estimated from phase space trajectories of observed 500 hPa height over the Northern Hemisphere. As a first estimate the dimensions of attractors are about 11.5 and the doubling time of the initial error is 6 to 7 days for original data. But the former is shorter and the latter is longer for low fre-quency data set.To verify if the predictability estimated by this method and by general circulation model is identical, the doubling time of the initial error of a model data set by both methods is estimated. It is shown that the predictability obtained from phase space trajectories is overestimated to sufficient small initial error. But it is underestimated to the time be-ing equal to the climatological RMS error.