Current Issue

• PRELIMINARY ANALYSIS ON THE STRUCTURE OF WIND FIELD SOUNDED BY DOPPLER SODAR AT HUAYIN STATION
• Pan Tao;Hu Yinqiao;Lin Peishun
• 1992 Vol. 11 (4): 335-343. 
• Abstract ( ) PDF (623KB) ( )
• The structure of Planetary Boundary Layer(PBL) has been analysed preliminarily by using the data sounded by Doppler Sodar in August, 1990 at Huayin station, which is in the "HEIFE" area. The results show that it is an effective method to determine height of the PBL using the data of echo intensity of Doppler Sodar. Evolution feature of the PBL's height is: the Mixed Layer (ML) increases rapidly in daytime, but it can last for a short time, while Stable Boundary Layer(SBL) can last for a long time in nocturnal. When the SBL developing deeply, a new stable layer grows between in the ground layer, hence a structure of multi-layer SBL occurs. The normalized variance of vertical wind-speed in the ML agree well with that of Lenschow's(1980). A completed process about formation, growth and disappearance of the Low-Level Jet(LLJ) was observed under the background that a cold front passed on 20 August.

• A STUDY OF DISSIPATION RATES OF THE TURBULENT KINETIC ENERGY AND TEMPERATURE VARIANCE IN THE GOBI DESERT REGION
• Liu Xiaohu;Wang Jiemin
• 1992 Vol. 11 (4): 344-352. 
• Abstract ( ) PDF (531KB) ( )
• In the paper, turbulent energy dissipation rate e and temperature variance disssipation rate N have been analysed by using turbulent energy spectrum theory in inertial subrange in the Gobi desert region. The dimensionless dissipation rates of turbulent energy( Φ _ε) and temperature variance( Φ _N) are ??? The turbulent kinetic energy budget and temperature variance budget are discussed. Mean while, the scaling parameter u _* and T _* in surface layer are calculated by the spec-tral density dissipation technique and compared with the result of eddy-correlation method, both of them are in good agreement.

• DIRECT SOLAR SPECTRAL MEASUREMENTS IN DESERT RANGE
• KongQinxin;Xiong Xiaozhen;LiuGuangren
• 1992 Vol. 11 (4): 353-360. 
• Abstract ( ) PDF (536KB) ( )
• In this paper, direct solar spectral measurements are reported during two intensive observing periods of the "HEIFE" in Apr. and Oct. 1991 in desert range. By analysing data of the atmospheric optical properties, the results are as follows:(1) The average spectral transparency of atmosphere is 0.723(for wavelength 500 nm) on clear or fine day.(2) The wavelength exponent a and the Angstrom turbidity coefficient β have an inverse relation. By using β= Aexp( Bα) to fit, the correlation coefficient is 0.872.(3) The aerosol optical thickness not only relates to aerosol concentration near the ground, but also depends on its size distribution, vertical profile, and chemical composition of the particles.

• THE CHARACTERS OF MICROMETEOROLOGY ON FARMLAND IN OASIS IN HEIHE REGION
• Zhang Qiang;Hu Yinqiao;Wang Xihong
• 1992 Vol. 11 (4): 361-370. 
• Abstract ( ) PDF (647KB) ( )
• In the paper, the data observed from Linze micrometeorology station during from June 1990 to September 1991 in the"HEIFE" have been analyed. The initial results have been get, which are about the characters of micrometeorology on farmland encircled by shelter belt in Oasis in drid area.

• THE BULK TRANSFER COEFFICIENT OVER DESERT AND GOBI IN HEIHE REGION
• Zuo Hongchao;Hu Yinqiao
• 1992 Vol. 11 (4): 371-380. 
• Abstract ( ) PDF (582KB) ( )
• In this paper, the "HEIFE"data during the period from 16 August to 15 September, 1990 over desert and Gobi are used to investigate bulk transfer coefficients. The results show that the neutral bulk transfer coefficients over desert and Gobi are 2.2×10 ^-3 and 1.6×10 ^-3, respectively. The roughness lengths over desert and Gobi are 4.5-10 ^-3 and 1.7-10 ^-3m, respectively. Variation of the neutral bulk transfer coefficients with wind speed is small. The empirical relationships among the bulk transfer coefficient, the bulk Richardson number and roughness length are given. The results are checked by the "HEIFE" data during another period.

• PRELIMINARY STUDY OF SURFACE SOLAR RADIATION PROPERTIES IN "HEIFE"AREA IN LATE SUMMER
• Zou Jiling;HouXuhong;JiGuoliang
• 1992 Vol. 11 (4): 381-388. 
• Abstract ( ) PDF (532KB) ( )
• In this paper, the variation properties for the components of surface solar radiation are analysed by using the short-period observational data of radiation balance at Linze(Oasis), Huayin(Gobi), Pingchuan (where Oasis and Desert intersect) and Desert stations in August 1990. The results show that the global radiation in these regions is very strong. At each of the four stations, the daily variation of global radiation shows corresponding variation along with the increasing or decreasing of the solar zenith angle. Except at Pingchuan station, the daily mean variations of surface albedo at the other stations are "U" types. When the daily mean totals of effective radiation are compared, we see that the value at Huayin is the largest one. The daily mean total of net radiation at Linze is the largest one.

• THREE-DIMENSION NUMERICAL SIMULATION OF EVOLUTION FOR THE MEAN STRUCTURE OF THE PBL IN HEIHE REGION
• Cheng Linsheng;Peng Xindong
• 1992 Vol. 11 (4): 389-399. 
• Abstract ( ) PDF (725KB) ( )
• An improved and developed high-resolution three dimensional mesoscale numerical model is used to simulate evolution of clear planetary boundary layer(PBL) in Heihe region with complex underlying surfaces and terrain, by using the data of FGGEⅢb in July 1979. The simulated results show that this model is capable for simulating mean structure and its evolution in the PBL in this region during Summer. The evolution of simulated surface fluxes is basically in agreement with some results of observational analyses, however, there are some differences because of different underlying surface. The 18 hours simulation for the evolution of the mean structure in the clear PBL is able to distinguish obviously different features between daytime and nocturnal. A mixed layer(ML) is progressively developed and built up after 8 BLT during the daytime, which reaches its maximum depth 1.5 km about 16 BLT, this mixed layer may be persisted until 21 BLT. A stable boundary layer during nocturnal is built up about 22 BLT. However, either daytime or nocturnal, the mean structure: and its evolution for the PBL are obviously affected by the inhomogeneity of the underlying surface.

• NUMERICAL SIMULATION OF ATMOSPHERIC BOUNDARY LAYER OVER INHOMOGENEOUSUNDERLYING SURFACE
• Sang Jianguo;Wu Yidan;Liu Huizhi;Pan Naixian;Chen Jiayi;Zhang Aichen
• 1992 Vol. 11 (4): 400-410. 
• Abstract ( ) PDF (640KB) ( )
• Two-dimensional numerical model combined with NP89 surface parameterization scheme developed in HAPEX is used to simulate the atmospheric boundary layer over the border of Gobi-oasis. In the simulation moisture inversion phenomena are analysed numerically. Finally some parameters sensitivity tests are conducted.

• A NUMERICAL SIMULATION OF ONE-DIMENSIONAL LAND-SURFACE PROCESS MODEL
• Niu Guoyue;Wang Jieming
• 1992 Vol. 11 (4): 411-422. 
• Abstract ( ) PDF (690KB) ( )
• In this model, the energy exchange processes in SPAC(Soil-Plant-Atmosphere Continuum) such as net radiant energy R _n, latent heat LE and sensible heat H have been described. Necessary modifications have been made in the parameterization of the internal processes. It can be divided into three parts: soil, plant and a reference level in the atmosphere. Six equations are contained in this model. In order to describe in detail hydro-logical and thermal processes in soil, the soil is divided into 15 layers in logarithm. The fluxes of net radiant energy R _n, latent heat LE and sensible heat Hhave been calculated and compared with the observed fluxes by using the data of Linze, Zhangye and Desert stations, which are in "HEIFE" region and stand for different underlying surfaces. The modeled fluxes agree well with the observed ones. The results show that this model can simulate energy exchange processes over different underlying surfaces. It can be used in the study of climatology and ecology.

• SIMULATION OF STOMATAL BEHAVIOUR AND TRANSPIRATION OF SINGLE LEAF OF SPRING WHEAT
• Zheng Hailei;Huang Zichen
• 1992 Vol. 11 (4): 423-430. 
• Abstract ( ) PDF (484KB) ( )
• A synthesis model of single leaf stomatal movement has been established based on the theory of Jarvis and field observations of various environmental factors such as solar radiation and water vapour deficit etc. for spring wheat. Theoretical analysis of the model shows that the sensitivity of stomatato to various factors is in the following order:(1) radiation, leaf temperature, leaf water potential and water vapour deficit at low solar radiation intensity and(2) leaf temperature, leaf water potential, solar radiation and water vapour deficit at high solar radiation intensity. Furthermore, another function describing single leaf transpiration rate has been deduced from the stomatal model. A comparison between the data calculated by this model and by modified Penman-Monteith equation and the observed data demonstrate that the observed data were slightly higher than the data calculated by this model and were slightly lower than those by modified Penman-Monteith equation.

• ESTIMATION OF THE SURFACE PARAMETERS OVER HEIHE RIVER REGION BY MEANS OF METEOROLOGICAL SATELLITE DATA
• Chen Tianyu;Chen Qian
• 1992 Vol. 11 (4): 431-439. 
• Abstract ( ) PDF (2656KB) ( )
• In this paper, by using NOAA satellite AVHRR data from January to June 1987, in the region of over 37.66°-39.88°N and 98.5°-101.5°E(including the upper and middle reaches of Heihe River), some surface parameters that concern surface properties, such as snow cover, vegetation index and surface reflectances, etc., have been estimated. According to these estimated results, the surface properties can be identified. Relying on these estimated surface parameters, we have analyzed the variation of time-space of surface properties, for example, the variation of snow cover and growing condition of crop with time, etc.

• SEASONAL VARIATION OF SURFACE ALBEDO AND VEGETATION INDEX OVER HEIHE EXPERIMENTAL AREA
• Wu Aisheng;Zhong Qiang
• 1992 Vol. 11 (4): 440-450. 
• Abstract ( ) PDF (700KB) ( )
• Surface albedo and vegetation index over Heihe experimental area in January, April, August and October are derived from NOAA 10/11 AVHRR data. Seasonal variations in surface albedo and vegetation index are discussed over the different underlying surfaces. In the method to derive surface albedo, more detail focuses on the problem of the anisotropic correction for the reflected radiance. It's shown that surface albedo of every surface type over the experimental area has obvious seasonal variation. The spatial distribution of surface albedo in each season can be shown quite well in satellite image. In summer, due to the great difference of vegetation index between desert/Gobi and farmland area, vegetation index image has better capability of showing the characteristics of complicated underlying surfaces. In winter, because the vegetation index of farmland area is reduced to approach to that of desert area, its image's capability of identifying the underlying surface types become much weak.

• A REAL-TIME, LOW COST TURBULENCE DATA ACQUISITION AND PROCESSING SYSTEM
• Wang Jiemin;Cui Tiemin;Ichiro Tamagawa;Yasushi Mitsuta
• 1992 Vol. 11 (4): 451-459. 
• Abstract ( ) PDF (589KB) ( )
• A micro-computer controlled turbulence data acquisition and processing system has been developed for the Program on Atmosphere-Land Surface Processes in Heihe River Basin(HEIFE). The turbulence sensors are mainly a 3-D sonic anemo-thermometer(Kaijo-Denki DAT-300) for wind and temperature, and an infrared hygrometer and the associated Humicap sensor(Kaijo-Denki, AH-300) for humidity measurements. Sometimes a 12 μm tungsten wire thermometer and a fine wire(80 μm) thermocouple psychrometer are also used in measuring temperature and humidity fluctuations. The proper facing of the sonic anemometer is adjusted by an Emotator; the tilt angle of its vertical component is checked carefully and recorded through a Clinometer. 8 to 12-channel signals, after active 10 Hz low pass filters, are transferred to a 12-bit A/D converter, and then, an IBM PC compatible computer. In most cases data is sampled at 10 Hz during 30 to 45-minute runs. Wind, temperature, and humidity fluctuation signals are visually displayed on the screen, which supplies a feature of real-time monitoring on the original data series. With well-done software the data could be processed within 10 minutes after each run, including eddy correlation calculations and spectra analysis, with paper printing or data file output of the concerned statistical quantities, such as means, variances, correlations, stability parameter, momentum, heat, and water vapor fluxes, and the power spectra of wind components, temperature, specific humidity, and the cospectra of momentum and heat flux, etc.. Some proper treatments for the original time series, such as despiking, detrending, and some corrections; to the sensor probes are also appropriately considered in the data processing procedure. As checked by the analyzed results, the turbulence data collected are of high quality. This system and the associated data processing software form a good basis for the turbulence measurements in HEIFE Intensive Observation Periods.

• THE INSTRUMENTAL ACCURACY AND OBSERVATIONAL ERROR ABOUT MICROMETEOROLOGICAL MAST OF CHINESE SIDE IN "HEIFE"
• Zhang Qiang;Hu Yinqiao
• 1992 Vol. 11 (4): 460-469. 
• Abstract ( ) PDF (663KB) ( )
• In the paper, it has been analysed that the accuracy of the instruments and the observational error of fluxes during the Fundamental Observing Period in "HEIFE" The results.show that the accuracy of instruments an; able to satisfy the observational requirement in atmospheric surface layer.

• THE DISCUSSION OF MEASURE ACCURACY OF EPPLEY PIR PYRGEOMETER
• Jiang Hao;Shen Zhibao
• 1992 Vol. 11 (4): 470-478. 
• Abstract ( ) PDF (634KB) ( )
• In this paper, the measure accuracy of PIR pyrgeometer. and its effect factors are discussed on the basis of the structure, performance and work principle of the pyrgeometer. The characters between "simple" and "accurate" measure method are compared. The applied condition and the range of measure accuracy are given and some methods are given to get higher measure accuracy in some special conditions. The analysis and experiments show that: The "accurate measure" method has a good measure accuracy and wide ambient adaptability. The "simple measure" method has a general accuracy, is easy operated and calculated. But when the air temperature is over the limited value, the accuracy is very bad. In all of the effect factors, the thermal radiation of pyrgeometer is important. Using the "simple measure" method, the measure accuracy is close relation to the performance of battery in the pyrgeometer. The strong solar radiation has some effect to the measure accuracy, it can be removed by correction.

• THE EXPERIMENTAL STUDY OF THE REPEATED MEASURING NUMBER OF THE SOIL WATER CONTENT
• WangYaoqi;WuJingzhi;WeiZhigang;Liu Wei;Gao Hongchun;Qiu Chuantao
• 1992 Vol. 11 (4): 479-484. 
• Abstract ( ) PDF (414KB) ( )
• According to the space alteration level of the soil water content, using the mathematic statistics method the needful repeated measuring number of the soil water content has been decided under the accuracy of 10% and 0.90 degree of confidence. The needful repeated measuring number at Zhangye experimental site is 5 times above 80 cm; 8 times for 90 cm and 10 times for 100cm in soil and at Linze experimental site that is 12, 13, 14times for 5, 70 and 80 cm layers in soil, respectively. At the rest layers that is less than 7 times. If the accuracy is 15% and the degree of confidence is 0.90, the needful measuring number will be less than 6 times at Zhangye and less than 8 times at Linze.