Current Issue

• THE SOURCES OF AEROSOL IN THE LOWER LAYER ATMOSPHERE AT WUDAOLIANG OVER QINGHAI-XIZANG PLATEAU Ⅰ. FACTOR ANALYSIS AND ITS RESULTS
• Liu Haiyan;Zhang Xiaoye;Shen Zhibao
• 1997 Vol. 16 (4): 337-344. 
• Abstract ( ) PDF (290KB) ( )
• The factor analysis(FA)、enrichment factors(EF) and rare-earth element(REE)distribution models were employed for searching the sources of atmospheric aerosol and their seasonal variation at Wudaoliang over Qinghai-Xizang Plateau. The aerosol samples were sampled in autumn(September~October, 1993), spring(April~May, 1994) and summer(July~August, 1994). The results show that there are three sources of the aerosol at Wudaoliang, they are earth crustal aerosol(soil dust), pollution aerosol and marine aerosol. The soil dust is the main source of the aerosol at Wudaoliang, their mass concentration is about 80% of the totals of the aerosol. The air pollution is not serious, the mass concentration of pollution aerosol is about 5.0%~12.0% of the totals. The marine aerosol was fund only in summer and autumn.

• THE SOURCES OF AEROSOL IN THE LOWER LAYER ATMOSPHERE AT WUDAOLIANG OVER QINGHAI-XIZANG PLATEAU Ⅱ. SOURCES REGIONS AND TRANSPORT
• Shen Zhibao;Zhang Xiaoye;Liu Haiyan
• 1997 Vol. 16 (4): 345-352. 
• Abstract ( ) PDF (291KB) ( )
• Based on the results of aerosol source analysis and the characteristics of the atmospheric circulation over Qinghai-Xizang Plateau and its surrounding area as well as the relationship of the variations between the aerosol concentration and some meteorologial elements, the source regions of the aerosol in the lower atmosphere at Wudaoliang were discussed. There are two main permanent pollution sources which affect the lower atmosphere in the year. The automobile emission is also a pollution source in summer and autumn. The marine aerosol is transported together with the watervapor from the Bay of Bengal and northeastern Arabian sea when the summer pattern of atmospheric circulation sets up and maintains, so that it occures only in the rainy season and the variation of its concentration is correlated with precipitation. The soil dust source is mainly at the Plateau in summer and early autumn, but the dust caused by dust storm in the arid region from the Northwestern China to the Middle Asia can be transported to the Plateau in spring and winter.

• THE EFFECTS OF AEROSOL OPTICAL ABSORPTION CHARACTERISTICS ON LOWER ATMOSPHERIC HEATING RATES
• Su Wenying;Chen Changhe
• 1997 Vol. 16 (4): 353-358. 
• Abstract ( ) PDF (221KB) ( )
• The diurnal variation of the imaginary part( k) of the aerosol refractive index is determined according to the parameterization method and its effects on shortwave heating rates are considered. We find that if k takes daily average values instead of its hour-to-hour values, the atmospheric aerosol heating rates will be overestimated. The overestimated maximum is about 1.6℃/d.

• THE ANALYSIS ON THE SURFACE RADIATION BUDGET OVER INSIDE AND OUTSIDE OF OASIS EDGE
• Wen Jun;Wang Jiemin
• 1997 Vol. 16 (4): 359-366. 
• Abstract ( ) PDF (301KB) ( )
• A field experiment of "Arid Environment Comprehensive Monitoring 95" was operated in August, 1995.The experimental sites are located in near Oasis edge area in Hei River basin of Northwest Chain.The analytical results of the observational data show that the characteristics of radiation budget, surface albedo and contribution of radiation flux density components to net radiation flux density are different between inside and outside of the Oasis side.The discrepancy of downward radiation flux density between two sites is small.Albedo is bigger over Gobi site than that over Oasis site. Variation of albedo with solar zenith angle is mainly caused by near-infrared albedo.The upward long-wave radiation over Gobi is bigger than that over Oasis site during daytime.Net radiation flux density over Oasis is bigger than that over Gobi.The discrepancy of net radiation is mainly caused by albedo and thermal condition of the land surface.

• A DIAGNOSTIC STUDY ON SURFACE SENSIBLE HEAT FLUX ANOMALY IN SUMMER OVER THE QINGHAI-XIZANG PLATEAU
• Li Dongliang;Zhang Jijia;Wu Hongbao
• 1997 Vol. 16 (4): 367-375. 
• Abstract ( ) PDF (321KB) ( )
• In this paper, the monthly mean surface sensible heat flux for 60 stations during period from 1961 to 1990 over the Qinghai-Xizang Plateau was calculated, and the basic climatic features and the space anomaly structure and time evolution tendency have been diagnosed systematically by principal component analysis, a periodic function and a random function and power spectral analysis methods. The result shows that the surface sensible heat flux is remarkably positive in summer, usually the sensible heat flux interannual change is large too. The first space pattern of interannual anomaly of the surface sensible heat flux over the Qinghai-Xizang Plateau is south-north discrepancy. The surface sensible heat flux increases constantly in main body and east of the Qinghai-Xizang Plateau and has a decrease tendency in the Qaidam Basin, eastern Qinghai province, and western Xizang in summer, and there are quasi-three, -seven and -thirteen years periodic oscillation for the interannual variation.

• A METHOD IMPROVING MONTHLY EXTENDED RANGE FORECASTING
• Zhang Peiqun;Chou Jifan
• 1997 Vol. 16 (4): 376-388. 
• Abstract ( ) PDF (525KB) ( )
• Based on the theory that the high dimensional phase space of a forced dissipative nonlinear system will eventually evolve into a low dimensional attractor, while a great deal of small-scale high frequency patterns are dissipated, an approach of improving extended range forecast is put forward. In which a set of EOF bases holding up the climatic attractor is gained from historical weather data to remove small-scale high-frequency disturbances which distort the monthly mean field.Two numerical experiments of monthly mean forecast, for January and July, have been performed by using T42 global spectral model and FGGE data. The results show that the AC of monthly mean forecasting field is apparently increased by applying the approach put forward in this thesis, which means the approach has effect on enhancing the forecast skill.

• NUMERICAL SIMULATION OF BOUNDARY LAYER STRUCTURE WITHIN COMPLEX TOPOGRAPHY
• Yu Xing;Wang Xiaoling;Dai Jin;Yang Wenfeng;Li Zhaoyuan
• 1997 Vol. 16 (4): 389-401. 
• Abstract ( ) PDF (495KB) ( )
• A three dimensional nonhydrostatic meso-β-scale meteorological model was developed to simulate influence of dynamic and thermodynamic effects on structure of boundary layer. Vertically, terrain-following coordinate was adapted. Fine grids were used to improve spatial resolution and with E-ε energy closure scheme. Effects of slope direction and vegetation were taken into consideration for solar radiative absorption and flux of surface latent heat and moisture, respectively, in parameterization. Numerical experiments and simulations were performed in Guanzhong area, Shaanxi province. The results show that complex topography has a large influence to vertical flow field and low-level wind field. Air lifts on windward slope and sinks on lee side. Lee wave is easy formed when exists a stable stratification, local circulation is readly to develop under the combination effects of horizontal temperature gradient and lee wave when stratification is unstable. Besides, topographic heating, air lifting on windward slope and lee wave play an important role in vertical transport of moisture and energy.

• THE EFFECT OF MAKING LAND TYPHOON DEPRESSION ON HEAVY RAIN IN EASTERN PART OF LOESS PLATEAU
• Liu Zichen;Liang Shengjun;Zhang Jianhong
• 1997 Vol. 16 (4): 402-409. 
• Abstract ( ) PDF (288KB) ( )
• In this paper, climatic analysis on 3 case heavy rain around making land typhoon depression in the Loess Plateau since 1980's and dynamic diagnosis analysis about torrential rain around 9608 typhoon depression have been done.The results show that the main mechanism of heavy rain formation is the influence of the esterly jet around typhoon depression, low-pressure system in westerly belt and the lifting of surface cold front.The result provides theory bases for this kind of torrential rain forecasting.

• THE INFLUENCES OF LANZHOU URBAN DEVELOPMENT ON LOCAL CLIMATE
• Bai Huzhi;Zhang Huanru;Zhang Cunjie
• 1997 Vol. 16 (4): 410-416. 
• Abstract ( ) PDF (240KB) ( )
• Features of climatic variation of Lanzhou and influences of urbanization development on local climate of city and suburbs are studied. The results show that the ascent size of mean temperature in Lanzhou since 1980's is about four times as compared to that of the Gansu province relative to 1960's~1970's.The interannual and seasonal variational characteristics of other factors is obvious.The differences of the annual and seasonal mean temperature、mean maximum and minimum temperature between Lanzhou city and its suburbs are gradually increasing.The annual and seasonal differences of rain day and the sunshine duration are obviously decreasing.

• POTENTIAL APPLICATION OF LINEAR DEPOLARIZATION RATIO( L _DR) OF C-BAND DUAL LINEAR POLARIZATION RADAR
• Liu Liping;Wang Zhijun;Qian Yongfu
• 1997 Vol. 16 (4): 417-424. 
• Abstract ( ) PDF (288KB) ( )
• Linear depolarization ratio( L _DR) is a important parameter for cloud and precipitation observed by dual linear polarization radar. In this paper, the L _DR of particles with liquid and ice phase for C-band wave-length is calculated, and the relationships between L _DR, Z _DR and the orientation and size of particles studied. The results show that values of L _DR depend on the Z _DR, orientations and the phases of particles, the L _DR reflects the information of orientation and the shapes of particles, which is valuable for the microphysical process of cloud and the hail distinguishing. The result is reference for the observation of L _DR in dual linear polarization radar and the base for the study of cloud and precipitation by the L _DR.

• ON MECHANISM TO FORECAST THE RAINFALL IN FLOOD SEASON UTILIZING THE LENGTH OF THE MOON'S SHADOW ON 15 LUNAR CALENDAR JANUARY IN ULANQAB LEAGUE DISTRICT
• Wei Zhigang;Zhang Shuangyin
• 1997 Vol. 16 (4): 425-432. 
• Abstract ( ) PDF (295KB) ( )
• In this paper, at first, the method to forecast the rainfall in flood season utilizing the length ( L) of the moon's shadow on 15 lunar calendar January in Ulanqab League district is introduced. Then, the following mechanism is pointed out: L indicates the lunar declination at the upper central meridian passage on 15 lunar calendar January. When L > 5.1 cun, the maximum tide-generating force at the new and full moon in flood season is positive(negative), it causes the rainfall is much(little) from April to September in Ulanqab League.

• THE IMPACT OF THE MERIDIONAL BASIC FLOW AND OROGRAPHY ON INERTIA- GRAVITATIONAL WAVE
• Wu Hong;Lin Jinrui
• 1997 Vol. 16 (4): 433-439. 
• Abstract ( ) PDF (231KB) ( )
• Using the shallow-water wave equations and WKB methods, the effect of the vertical shear of meridional basic flow and the orography with south-north direction on the velocity, stability and development of the inertia-gravitational wave are disscussed.

• THE REAL TIME SHORT-RANGE PREDICTION OF SEVERE CONVECTIVE WEATHER AND θ _se CHARACTERISTICS METHOD
• Hu Fuquan;Guo Min;Zhou Junqun
• 1997 Vol. 16 (4): 440-445. 
• Abstract ( ) PDF (213KB) ( )
• θ _se characteristics method has got accuracy of above 90 precent which was applied to make short-range prediction of severe convective weather in Shanghai area from 1995 to 1996. In this paper, the authors research the theoretical connotation of θ _se characteristics method by dynamics, energetics and probability statistics, and explain the software product of prediction.

• A SURVEY IN THE STUDY OF AREA EVAPORATION(EVAPOTRANSPIRATION) OVER THE HETEROGENEOUS LANDSCAPE
• Ma Yaoming;Wang Jiemin
• 1997 Vol. 16 (4): 446-452. 
• Abstract ( ) PDF (278KB) ( )
• The traditional method, numerical simulation method and remote sensing method on the evaporation(evapotranspiration) study over the heterogeneous landscape are introduced and discussed in this paper. At the same time, the special role of remote sensing method on the estimation of the evaporation(evapotranspiration) over the heterogeneous landscape is also discussed. The advantages and weakness of satellite remote sensing method are summarized and the future development of the estimation of evaporation(evapotranspiration) over the heterogeneous landscape with the aid of remote sensing and field observation are discussed in the end of this paper.