Vol.3, NO.2, 1992

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A Study of the Relationships Between Optical Constants of Ice and Temperatures in the Spectral Region from the Ultraviolet to the Middle Infrared
1992, 3(2): 212-219.
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Abstract:
In the paper, the structure of ice and its optical properties are discussed briefly. The relationships between optical constants of ice and temperatures in different spectral regions are estimated by using the classical polarization theory. Optical constants of ice form the ultraviolet to the middle infrared and in the range of the earth atmosphere temperature are computed. The results show that the influence of temperatures on optical constants of ice crystals of clouds should be considered in the theoretical calculations of scattering and radiative transfer in cirrus clouds
The Real Time Processing for Geostationary Meteorological Satellite Image Data
1992, 3(2): 129-135.
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Abstract:
A real time processing method for geostationary meteorological satellite image data were developed by hardware. With the help of the method, the zooming, enhancing, compositing, and mapping of geostationary meteorological satellite image can be completed under the condition of lack of computer system. Also, the image can be output from the facsimile machine. This method has been used in the GMS satellite stretched VISSR image receiving and processing system developed by authors.
Characteristics of Large Amplitude Gravity Wave of Squall Line Behind the Cold Front
1992, 3(2): 136-144.
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Abstract:
In this paper, a squall process occurring behind the cold front in Chang Jiang—Huai He area is analysed with the help of the enhanced observational data. The analysis shows the genesis and development of squall are related to the mesoscale cold surge activities. The cold surge is characterized by the large amplitude gravity wave. The gravity wave is trapped by Dabie Shan Mountain in the process of propagation and the edge front is formed at the east side of Dabie Shan Mountain. The propagation of edge front shows the feature similar to Kelvin wave. The character of large amplitude gravity wave in the boundary layer is very obvious. This kind of large amplitude gravity wave trapped by the mountain may be a trigger mechanism of the squall line behind the cold front.
A Study of Budget of Potential Vorticity of Blocking High During the Drought Period in Summer of 1980
1992, 3(2): 145-156.
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Abstract:
A diagnostic study of the average characteristics and maintenance mechanism of the blocking situation in East Asia during the drought period in summer of 1980 (1 July－10 September) has been made by use of quasi-geostrophic potential vorticity equation. It has been shown that the blocking high in East Asia is a kind of deep and warm anticyclonic system of unusually low potential vorticity. On the one hand, its maintenance is related to the eddy transport resulting from the long wave trough in the Ural region upstream, on the other hand, and more importantly, it is associated with the transport of the air of low potential vorticity originating in the Tibetan Plateau. The estimate of budget of potential vorticity has further indicated that the eddy forcing term is nearly balanced out by the advection term of the mean flow. This face implies that the eddy transport of potential vorticity may be an important factor responsible for maintenance of unusually low potential vorticity in the blocking area and prohibiting the blocking high from the downstream advection.
A Diagnostic Study of a MCC with Severe Rain over Northeast China in Summer
1992, 3(2): 157-164.
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Abstract:
A real-time quasi-geostrophic omega diagnostic scheme, based on Hoskins′-vector analysis, is applied to a MCC (mesoscale convective complexes) with severe convection over northeast China in summer. And the vertical motion of the system is computed by use of the ten-level meso- scale nonlinear model. The principle results are as follows: thermal advection is an initial triggering condition for the genesis of this MCC. The cumulus heating and large –scale latent heat release are, generally, very crucial physical factors for the intensification and development of the system. The divergence and the rotational component of the -vector and the geostrophic frontogenetical function expressed by -vector would provide forecasters with a lot of useful information.
The Warming and Propagating Features of the Equatorial Pacific Surface Temperature During El Nino Events
1992, 3(2): 165-172.
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Abstract:
In this paper, firstly the features of long variation of the Equatorial Pacific Sea Surface Temperature (EPSST) are probed by use of the spectrum analysis of the principal component of time coefficients from standared EOF. Then the warming and propagating features of EPSST during El Nino events are studied by using the CEOF method. The results show El Nino events have three patterns in the light of their spatial warming range: (1) warming in the central and east Pacific; (2) warming in the whole equatorial Pacific; (3) warming only in the east Pacific. Furthermore, they could also be divided into other three patterns based on the propagating features of EPSST during their development: (1) warming first in the east Pacific, then propagating westward; (2) warming occurring in the east and west Pacific simultaneously, then propagation towards the central Pacific; (3) warming first in the west Pacific, then propagating eastward.
The EOF Analysis of 50 hPa Potential Height Anomaly Field in the Northern Hemisphere and Its Comparison with the Tropospheric Field
1992, 3(2): 173- 180.
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Abstract:
In this paper, we analysed the 50 hPa potential height anomaly field in the Northern Hemisphere using the EOF method. It is indicated that (1) there are several stationary circulation patterns in 50 hPa field of the Northern Hemisphere, and the stable fitting precision of EOF, (2) there is a obvious “see-saw” phenomenon between high latitude and middle latitude in the 50 hPa potential height anomaly field of the Northern Hemisphere, (3) the quasi-biennial to quasi-triennial oscillation and quasi-four month oscillation of 50 hPa circulation field in the Northern Hemisphere exist obviously, and the QBO phenomenon of equatorial stratosphere is also verified, and (4) as compared between the 500 hPa and 50 hPa field, the first and second characteristic vectors of potential height anomaly field have the similar spatial distribution, but EOF expansion in the stratosphere whether the stability of fitting precision or the convergence is better than that in troposphere.
The Relationships Between Summer Rainfall in China and Tropical Circulation Anomaly
1992, 3(2): 181-189.
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Abstract:
Total rainfall percentage anomaly of summer in China has been estimated by using EOF method. The first three characteristic vectors of EOF represent three typical rainfall distribution patterns, respectively. In this paper, the features of tropical circulation of three rainfall distribution patterns are analysed, and correlation analyses of the time coefficients corresponding to the three characteristic vectors are discussed. The results show that there exists positive (negative) correlation between southern rainfall pattern and 850 hPa (200 hPa) equatorial zonal wind in the middle and eastern Pacific. Northern rainfall pattern is closely associated with 850 hPa and 200 hPa zonal wind in the vicinity of Australia. Middle rainfall pattern is related to the circulation anomalies in Indian ocean
The Study on Structure of the Offshore Tropical Storms and the Comparative Diagnoses of Energy Budget
1992, 3(2): 190-197.
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Abstract:
In this paper, a study on the structure of the offshore tropical storms is made based on the data of the severe tropical storm Ida (8006) and the typhoon Ellen (8309). It is found that the remarkable features of the offshore tropical storms are the obvious asymmetry in the air-flow field and the weak warm center. A comparative diagnostic research on kinetic energy budget and heating field of such a pair of tropical storms is carried out. It is emphatically pointed out that the decay mechanism of an offshore tropical storm is implicated in the asymmetric structure. This is because the warm area and the ascending motion area are biased from the center and not coincided with each other. The baroclinic transformation process from available potential energy to kinetic energy is very weak and even negative. The another decay mechanism is that the tropical storm maintains the characteristics of a tropical system for a long time after landing and then has not rapidly changed the main energy source from latent heat release into the baroclinic process. For the tropical storms which decay soon after landing, the maximum heating is stronger and its altitude is higher.
Energy Analyses of Vortices over the Qingzang Plateau in Summer
1992, 3(2): 198-205.
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Abstract:
Three vortices, which happened over the Qinghai-Tibet Plateau in June of 1979, are estimated in this paper by using apparent heat source equation, apparent moist sink equation, perturbation energy equations and vorticity equation. During the genesis and development process of the vortices, the vertical eddy transport of total heat (sensible heat and latent heat) caused by cumulus and turbulence is very important. When the atmosphere is conditional instability, the eddy transport by cumulus and turbulence makes the layer of the increment of vortices absolute vorticity higher. In addition, the eddy transport of total heat makes disturbance effective potential energy increase and then it is transformed into disturbance kinetic energy. Thus, the vortices will generate and develop.
Mechanism of Formation and Evolution Process of the Asian Continental Cold High in Winter
1992, 3(2): 206-211.
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Abstract:
By using a two-level global spectral model, the mechanism of formation and evolution process of continental cold high and topographic action in the model are studied. We find that clod high positions are determined by the continental cooling source of lower troposphere resulting from radiative cooling in the atmosphere and sensitive heat of the earth surface, and by the topographic dynamic sink. The results also show that(a) after cold high is formed, it moves southward owing to the action of cold advection in troposphere, its path and reaching latitude are related to the topographic action, (b) the heating sources formed by the sensitive heating transport on the sea-surface in winter play an important role for the variation of cold high movement.
The Climatic Characteristics over the Hei He River Experimental Central Area
1992, 3(2): 220-227.
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Abstract:
In this paper, according to the monthly mean climatic data over Linze of Ganshu Province during the period of 1967—1981, and their comparison results with Beijing data during the period of 1959—1980, the results show whether annual insolation duration or total solar radiant heat in Linze is larger by 0.19 and 0.16 time, respectively, than that in Beijing, annual rainfall of Linze is one-fifth less than in Beijing and annual evaporation in Linze is 1.2 times as large as that in Beijing. Subsequently, we also obtain the following results: the sensible and the latent heat flux in Linze is larger than that in Beijing, during the January to November, however, the momentum flux in Beijing is larger than that in Linze from milled ten-day of November to first ten-day of April of next year. In generally, the momentum flux of Linze is larger than that of Beijing.
The Relationship Between El Nino Events and the Rainfall, Historical Drought and Waterlogging in China
1992, 3(2): 228-234.
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Abstract:
By using the monthly total precipitations of 178 observational station in China (1951－1989),we have analysed the characteristics of precipitation of China in the years and next years of EI Nino events and differences between them. The precipitation to the northern area of the Changjiang River is less except in spring, and it is more than normal in the southern area of China except in summer, in the years of EI Nino phenomena onset. In the next years of EI Nino events the precipitation in the most areas of China have opposite tendency. The difference is obvious in the east of Northwest China, Sichuan basin and Qinghai-Xizang Plateau. Additionally, in recent 500 years, the relationship is close between the distribution of historical drought or waterlogging in China and EI Nino events.
Statistical Features of the Cold Waves Invaded China and Their Relation to the Snow Cover Area over the Eurasian Continent
1992, 3(2): 235-241.
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Abstract:
Using the record of cold waves invaded China during the 38 winter half-years from September 1951 through April 1989, statistical features of the cold waves are pantadly, monthly and yearly investigated. The cold waves are divided into three grades, i.e. , severe, strong and moderate. The statistical results are as follows: 1. From the accumulated monthly frequencies it is shown that severe cold waves occur most in November and March, but least in February. 2. Yearly frequences of the strong events of the severe cold waves together with the strong cold waves show obvious interannual variations, in which there are not only 2－5 year oscillations, but also about 20 yearly climatic variations. And, in the last twenty years the strong events tend to gradually decrease. In addition, the relationship between the cold waves invaded China and the winter snow area coved over the Eurasion continent has been preliminarily studied based on digitalizing the cold wave record.
The Kinetic Energy Balance of Two Summer Cyclones over the Changjiang-Huaihe Valley and Its Relations with the Large Scale Circulation
1992, 3(2): 242-247.
[FullText](2712) [PDF 334KB](1247)
Abstract:
In this paper, quasi-lagrangian methos is used to calculate the kinetic energy balance and the contribution to the cross contour kinetic energy generation by the rotational and divergent wind components. Their relations with the large scale circulation are also discussed. Main conclusions include: (1) the characteristics of kinetic energy varies according to the large scale circulation; (2) the horizontal transport of kinetic energy is determined by the locations of the cyclone relative to the jet stream; (3) there is large magnitude of kinetic energy generation (destruction) by the rotational wind component near the entrance (exit) region of a stable jet stream; (4) a slowly deepening cyclone wave is associated with significant kinetic energy generation by the divergent wind in the upper and lower layers; (5) the conversion of a summer cyclone wave into a typical extratropical cyclone occurs when an upper level trough with an associated jet stream moves towards the east coast and a large amount of kinetic energy is imported into the cyclone region.
The Calculation of Daily Evapotranspiration in the Field of Winter Wheat
1992, 3(2): 248-253.
[FullText](2906) [PDF 310KB](1366)
Abstract:
Based on the microclimatological data the daily evapotranspiration in the field of winter wheat during the period of heading and milky maturity is preliminarily calculated with the help of the Penman formulas and the other methods, such as energy balance, Bowen ratio and aero-dynamics. The modification of Penman formula is principally considered. The accuracy and error analysis of the formulas and methods above are evaluated by the results of water balance method, which can be regarded as a standard. The conclusions show that after being modified by the crop coefficient water content and heat exchange in soil as well as the surface temperature of evaporation. Penman formula can be used to calculate accurately the daily evapotranspiration of cropcovered field on the conditions of different energy and water supply
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