Current Issue

• THE SEASONAL VARIATION OF SURFACE HEATING FIELD OVER THE NORTHERN QINGHAI-XIZANG PLATEAU
• Ji Guoliang;Zuo Jiling;Lu Lanzhi
• 1997 Vol. 16 (1): 1-9. 
• Abstract ( ) PDF (307KB) ( )
• In this paper, the characteristics for seasonal variation of surface heating field are analysed by using the data of radiation budget observed at Wudaoliang during the period from September 1993 to August 1995. The results show that:in spring and autumn, the intensity of surface heating field increases and decreases rapidly, respectively, which cause the season transition. When the duration of surface snow cover is long and intensity of surface heating field is weakness in winter, the intensity of surface heating field is strong in next summer. The seasonal variation of surface heating field is obvious:the intensity is strong in summer and weakness in winter. When the duration of surface snow cover is long, surface albedo is large and the heat released from soil is smaller than that in no snow cover cause the surface heating field acts as a heat sink.

• CHARACTERISTICS OF CLOUD CLIMATOLOGY OVER QINGHAI-XIZANG PLATEAU
• Wei Li;Zhong Qiang
• 1997 Vol. 16 (1): 10-16. 
• Abstract ( ) PDF (230KB) ( )
• The geographic and vertical distributions of cloud over the Qinghai-Xizang Plateau are comprehensively analysed based on the International Satellite Cloud Climatoloyg Project(ISCCP) data, which is grided on 2.5°×2.5° during July of 1983 to June of 1990, and the cloud climatological data from the surface observations given by Hahn et al which is grided on 5°×5° during 1971 to 1981. The results will be useful to test the cloud simulations with climate models and study the effects of cloud-radiation interaction on the climate over the Plateau.

• THE CLIMATIC CHARACTERISTICS OF CLOUD RADIATIVE FORCING OF EARTH-ATMOSPHERE SYSTEM OVER QINGHAI-XIZANG PLATEAU
• Wang Keli;Zhong Qiang
• 1997 Vol. 16 (1): 17-22. 
• Abstract ( ) PDF (245KB) ( )
• The climatic characteristics of cloud radiative forcing of earth-atmosphere system over Qinghai-Xizang Plateau are analysed based on the data set of ERBE-S4 and ISCCP-C2. The results show that the greenhouse effect of cloud is stronger than the reflective effect of cloud in winter and weaker in other season.

• INFLUENCES OF SEVEN TIBETAN PLATEAU RAISING PROCESSES ON CLIMATE AND ENVIRONMENT
• Tang Maocang;Dong Wenjie
• 1997 Vol. 16 (1): 23-29. 
• Abstract ( ) PDF (244KB) ( )
• In this paper, it is systematically discussed that the influences of seven Tibetan Plateau raising processes on climate and environment. The cause of climate formation is analyzed by means of meteorological theory. The main conclusions are those: (1) the cause of hot-dry climate before elevation of plateau is that the efficiency of atmospheric heat engine is lower than after the elevation owing to flatter global landform;(2) at the beginning of Oligocene Epoch, the horizontal scale of plateau reached the critical scale of geostraphic adjustment of baroclinic atmosphere, following which atmospheric general circulation changed from "two vortexes in south pole and north pole stand facing each other" pattern into "three vortexes tripartite confrontation" pattern, or climate suddenly changed;(3) a series of variability in atmospheric general circulation, corresponding to the plateau's reaching 2 000 m, an important critical height, at 2.5 Ma B P is analyzed;(4) the energy balance of earth-atmosphere system at the Great Ice age is estimated, and the difference between the energy balance at the Grent and at present is contrasted, based on which the climate during that period is discussed, moreover, the mean plateau elevation is evaluated lower than 3 000 m at 0.5 Ma B P.

• SECULAR VARIATION CHARACTERISTICS OF SOLAR RADIATION AND AIR TEMPERATURE AT GOLMUD
• Ji Guoliang;Lü Lanzhi
• 1997 Vol. 16 (1): 30-35. 
• Abstract ( ) PDF (212KB) ( )
• The secular variation characteristics and the relationship between global radiation and air temperature are analysed by using the data of air temperature and global radiation from 1956 to 1994 at Golmud. The results show that decreasing tendency of the global radiation is non-obvious in 37 years. The annual mean air temperature is low in the 1960's, it rapidly increases in the 1970's and early appears about 10 years than that in eastern plain. There is a tendency of warming in winter and cooling in summer. The relationship between annual mean air temperature and global radiation is positive correlation of delay one year from the 1970's to 1990's. The relationship between the air temperature and global radiation for the same period is positive correlation in summer and is negative correlation in winter.

• A STUDY OF THE EFFECT OF SPECTRAL EMISSIVITY ON THE RETRIEVAL OF LAND SURFACE TEMPERATURE FROM SATELLITE
• Yang Wen
• 1997 Vol. 16 (1): 36-44. 
• Abstract ( ) PDF (308KB) ( )
• When using the split-window method for the retrieval of land surface temperature, the results show that the land surface temperature linearly depends not only on the brightness temperatures in channels 4 and 5 of AVHRR but also on the (1-ε ₄)/ε ₄ and (ε ₄ -ε ₅)/ε ₄ which are based on spectral emissivities of channels 4 and 5. The analyzing results are as follows:(1) If Δε(namely, ε ₄-ε ₅)=0, as ε ₄ varied from 0.94 to 1.00, the difference between land surface temperatures is more than 3.0℃. (2) If Δε≠0, the effect of Δε on the land surface temperature is more sensitive and more notable than that of ε ₄;When Δε>0, there may be a weaking between the effects of Δε and ε ₄ on land surface temperature;But if Δε<0, there is a enhancing between the effects of Δε and ε ₄. (3) If the error of land surface temperature is decreased to lower than 1.0℃, then the error of Δε must be less than 0.005.

• THE ANALYSIS OF TURBULENT FLUXES TRANSFER CHARACTERISTICS OVER NANSHA SEA REGION
• Ma Yaoming;Wang Jiemin;Zhang Qingrong;Mai Boqiang
• 1997 Vol. 16 (1): 45-51. 
• Abstract ( ) PDF (258KB) ( )
• The drag coefficient and the fluxes of momentum, sensible heat and latent heat for Nansha Islands sea region are described in this paper. The turbulence data were collected from Zhubi Island(10°52'N, 114°04'E) of Nansha sea region in September 1994. These fluxes are calculated by the eddy correlation method using these observed data. At the same time, these results are compared with the other air-sea interaction experiments and land surface processes experiment(HEIFE). The results show that the drag coefficient C D is equal to (am1.54±0.24)×10 ^-3 in this sea region; the heat of this sea region is transfered into atmosphere in the forms of sensible heat and latent heat during day and night, and the latent heat transfer is main role; the daily variation of sensible heat and latent heat in this sea region is not obvious as same as the land surface; the transfer of the daily mean sensible flux is much less than the land surface; the daily mean latent heat flux is much greater than the Gobi and desert, but it is similar to the oasis.

• THE FURTHER STUDY ABOUT SOUTH ASIA HIGH IN SUMMER Ⅰ. STATISTIC ANALYSES OF RELATIONSHIP BETWEEN IT AND PRECIPITATION DISTRIBUTION OVER NORTHWEST CHINA
• Zhang Qiong;Qian Zhengan;Chen Minlian
• 1997 Vol. 16 (1): 52-62. 
• Abstract ( ) PDF (382KB) ( )
• In order to analyse the relationship between the 100 hPa Southern Asia High(SAH) and the precipitation over Northwest China in Summer, in this paper, firstly, the basic activity characteristics of the SAH and the relationship between the SAH and the precipitation over Northwest China are analysed, utilizing daily historical synoptic map data and precipitation map data of July and August during the period of from 1970 to 1985. The results show: (1) the 100 hPa SAH in summer stays mainly over Qinghai-Xizang Plateau and its neighbourhood, it suggests the impacts of the Plateau on the SAH. (2) When the monthly mean SAH ridge line is located somewhat south, the precipitation over the Northwest China will increase. (3) During the continuous processes of eastern pattern of the SAH, it will be rainy in the eastern part of Northwest China, but the dry weather in the western part of the Northwest China. During the continuous processes of western pattern of the SAH, the whole region of the Northwest China has little rain. (4) We sum also up the distribution of rainy area of eastern pattern of the SAH.

• CLIMATIC CHARACTERISTICS ANALYSES OF SURFACE AIR TEMPERATURE VARIATIONS FOR YUNNAN PROVINCE DURING THE LAST ONE HUNDRED YEARS AND CHILLING DAMAGE WEATHER IN AUGUST
• You Weihong;Fu Baopu;Lin Zhenshan
• 1997 Vol. 16 (1): 63-72. 
• Abstract ( ) PDF (350KB) ( )
• In this paper, using multiresolving theory of wavelet analysis, the climatic characteristics of surface air temperature variations for Yunnan province during the last one hundred years and chilling damage weather in August are analysed. The results show that the surface air temperature variations for Yunnan province can be described as 4 hierarchies. They are the cold period before 1919, the warm period from 1920 to 1954, the cold period from 1955 to 1986 and the warm period after 1987. The larger timescale's hierarchical changes for Yunnan province obviously appear features of climate jump. The 1920, 1955 and 1987 are the jump points of climate change. The chilling damage weathers for Yunnan province in August are mainly during the cold period from 1955 to 1986. Corresponding to the smaller timescale's air temperature variations, the chilling damage weathers for Yunnan province in August are generally located in the climatic hierarchy which the surface air temperature is lower. The feature of utility can appear before several months of chilling damage weather occurring in Yunnan province. The adaptive multiresolution filtering method introduced into this paper is important for many actual problems such as climate forecast and etc..

• ANALYSIS OF AIR TEMPERATURE ANOMALY AND CATASTROPHE IN THIS CENTURY IN KUNMING CITY
• Wang Yu
• 1997 Vol. 16 (1): 73-80. 
• Abstract ( ) PDF (267KB) ( )
• The air temperature changing tendency, cold and warm ranges, frequency of air temperature and air temperature catastrophe are analysed based on the mean air temperature data for annual, summer(6~8) and winter(12~2) from 1921 to 1993 in Kunming city. The results show that air temperature rose from 1920', air temperature reached the maximum about 1940', then, air temperature fall down, it reached the minimum in 1970' and it rose slightly from 1980' in Kunming city. The warm range is from 1921 to 1954 and cold range, from 1955 to 1993. The high temperature anomaly appeared before 1950, low temperature anomaly, after 1960 and the frequency of air temperature anomaly is low. Air temperature catastrophe appeared in 1957 for annual mean, in 1955 for winter mean and no catastrophe for summer mean.

• MULTIPLE TIME SCALES ANALYSIS OF XI'AN CLIMATE CHANGE FOR LAST 50 YEARS
• Deng Ziwang;Lin Zhenshan;Zhou Xiaolan
• 1997 Vol. 16 (1): 81-93. 
• Abstract ( ) PDF (484KB) ( )
• In this paper, the abnormalities of monthly mean temperature and monthly precipitation in Xi'an for the last 50 years are analyzed by the Morlet wavelet transformation. It shows that the periodic variations are localized in time domain except 1-year natural period and 20~40 years long term variations. Because of the special geographic location, the relationships between the climate variation in Xi'an and ENSO are not strong. The combination of cold or warm and wet or dry climate states are different between long and short time scales. The climate change is regularity on long time scales while the climate variation is random and complicate on short time scales. The temperature variation is mainly random while the precipitation changes with a characteristic scale of 4~5 months.

• THE CALCULATION ALGORITHMS FOR AVERAGE WIND DIRECTION AND THEIR COMPARISON
• Qiu Chuantao;Li Dinghua
• 1997 Vol. 16 (1): 94-98. 
• Abstract ( ) PDF (170KB) ( )
• In this paper, four calculation algorithms for average wind direction and their comparison are given, these algorithms include arithmetic, scalar, unit vector and vector. The comparison of the results from these algorithms using the observation data was also made. Results are as follows: the results of arithmetic algorithm enlarge the percentage of south wind, the results of scalar algorithm cause a larger error when wind direction rotation cxceeds 360°. The unit vector has similar results with vector, and does not need wind speed. The unit vector is the best.

• STUDY ON THEORY AND APPLICATION OF DUAL-POLARIZATION RADAR IN CHINA
• Liu Liping;Wang Zhijun;Xu Baoxiang;Cai Qiming
• 1997 Vol. 16 (1): 99-104. 
• Abstract ( ) PDF (215KB) ( )
• Lanzhou Institute of Plateau Atmospheric Physics, Chinese Academy of Sciences has developed the first C band dual-polarization radar in China and studied the theory and application of the dual linear polarization radar from 1984 to 1995. In this paper, we reviewed the study result. This is for reference of radar meteorology and related area only.

• THE APPLICATION OF ARTIFICIAL NEURAL NETWORK FOR REGIONAL RAIN FORECAST IN QINGHAI PROVINCE
• Wang Fanqiang;Xu Wenjin;Chen Jielun;Wang Xin
• 1997 Vol. 16 (1): 105-112. 
• Abstract ( ) PDF (271KB) ( )
• The 24 h rain forecasting B-P neural network of Qinghai Plateau regional rain are established with regular synoptic data and ECMWF data for 5 mm, 10 mm and 25 mm fainfall synoptic processes. The results that learning from samples show, the artificial neural network can extract enough classified informations from original data and reach good historical fitness(≥95%). The forecast experiment made in 1994 and 1995 duing June~August is better.