Current Issue

• A NUMERICAL STUDY ON MESOSCALE CLIMATE OF INHOMOGENEOUS BOUNDARY LAYER OVER DRY LAND
• Chen Jiang;Chen Wanlong;Chen Yi-Leng
• 1993 Vol. 12 (2): 115-124. 
• Abstract ( ) PDF (650KB) ( )
• In order to investigate the interaction between the dry land inhomogeneous underlying surface(IUS) and the atmosphere,with the resulting influence on the boundary layer climate(BLC),the β-mesoscale model proposed by Nickerson et al.(1986) is used with some modifications done for our study.The revised model is subjected to the sensitivity experiment,and results show that it is highly sensitive to changes in the vegetative cover and background windspeed.Then the model is employed to explore the BLC's effects of the summer IUS located in a dry-land region of North China(around 40°N,100°E).

• CHARACTER OF WATER VAPOUR TRANSPORTATION IN THE SURFACE LAYER OVER DESERT NEAR OASIS
• Hu Yinqiao;Wang Junqin;Zuo Hongchao
• 1993 Vol. 12 (2): 125-132. 
• Abstract ( ) PDF (514KB) ( )
• An observation experiment about water vapour transportation over desert is carried out at desert station in the HEIFE on July 1991 to find the specific humidity profiles often appear minimum in the surface layer.The level of the minimun value is at the height of zero water vapour flux.The water vapour is transported downwards and the profile of specific humidity appears inverse humidity character above the zero flux height,but the vapour is transported upwards and the profile is evaporation character under the zero flux height.The water vapour flux is unconstant in the surface laved at a fixed level,can not represent the evaporativity and the latent heat flux on ground surface.

• ANALYSIS OF SENSIBLE HEAT FLUX BY USING THE SIMPLIFIED AERODYNAMIC APPROACH METHOD OVER HEIFE AREA
• Guo Xueliang;Wang Jiemin
• 1993 Vol. 12 (2): 133-140. 
• Abstract ( ) PDF (519KB) ( )
• A calculation is made with two methods of simplified aerodynamic approach for determining sensible heat flux over both desert and oasis.The first method is a statistical analysis between the sensible heat flux( H) and surface-air temperature difference( T _s- T _a);the second method is via a parameterization of heat transfer resistance( r _a).The results show that under unstable condition the relationship between sensible heat flux and( T _s- T _a) fits power law equation over oasis area,but over desert region the relationship between the sensible heat flux and( T _s- T _a) is influenced by wind speed.Application of this result in the estimation of latent heat flux( LE) can also give satisfactory results.A form for the added resistance in heat transfer process, kB ^-1=0.2 u( T _s- T _a),can be used over both desert and oasis area.

• CHARACTERISTICS OF THE PHOTOSYNTHETICALLY ACTIVE RADIATION OVER ZHANGYE REGION
• Ji Guoliang;Ma Xiaoyan;Zou Jiling;Lu Lanzhi
• 1993 Vol. 12 (2): 141-146. 
• Abstract ( ) PDF (427KB) ( )
• Photosynthetically Active Radiation( PAR) is an important energy source of photosynthesis for the green plants.In this paper,characteristics of the photosynthetically active radiation over Zhangye region are analysed and studied by using the data of solar spectral radiation during HEIFE FOP and BOP at Linze and Zhangye station,respectively.The results show:in clear case the ratio of PAR to global radiation is a range from 0.419 to 0.426 over Zhangye region and the seasonal variation is not obvious.In cloudy case,the ratio of PAR to global radiation is larger than that in the clear case,their seasonal variation is obvious,and the ratio is large in summer and small in winter.In addition,the empirical formula to calculate the PAR over Zhangye region is fitted base on the observed data and the distribution of PAR over Zhangye region is also discussed in this paper.

• RELATIONSHIPS BETWEEN GLOBAL RADIATION,SURFACE ALBEDO AND SOLAR ELEVATION ANGLE FOR SEVERAL UNDERLYING SURFACES IN THE HEIHE EXPERIMENTAL AREA
• Wu Aisheng;Zhong Qiang
• 1993 Vol. 12 (2): 147-155. 
• Abstract ( ) PDF (564KB) ( )
• In this study,the clear-day observational data of solar radiation at Zhangye,Huayin and Desert stations in January,April,August and October during the Heihe exprimental period(1991) are used to discuss the relationships between clear-day grobal solar radiation,surface albedo and solar elevation angle.The empirical functional relationships between surface albedo and solar elevation angle are obtained for different underlying surfaces and different seasons.The relationship between clear-day grobal solar radiation and solar elevation angle for each station is also given.Finally,the applications of these functional relationships in the retrieval of surface albedo from satellite data are also discussed.

• THE SPECTRUM CHARACTERISTICS OF GLOBAL RADIATION AND SURFACE ALBEDO OVER OASIS REGION IN HEIFE
• Jiang Hao
• 1993 Vol. 12 (2): 156-161. 
• Abstract ( ) PDF (434KB) ( )
• In this paper,the spectrum characteristics of global radiation and surface albedo over HEIFE oasis region are analysed on the basis of the spectrum data of global radiation and surface albedo observed over the Linze substation in HEIFE.The results are as following:(1) The ratio of the UV and visible radiation to global radiation are littler but the near-infrared is larger than other region.(2) The ratio of the UV and visible radiation to global radiation decreases in winter and increases in summer,the near-infrared radiation increases in winter and decreases in summer.(3) There is a obvious seasonal change for spectrum characteristics of surface albedo,it is related to the surface vegetation.(4) For each wave-length band,there are different variation type in different seasons.

• THE TOTAL ATMOSPHERIC WATER VAPOUR AND OZONE CONTENT CALCULATED BY USING THE DATA OF SOLAR DIRECT SPECTRUM OVER PINGCHUAN DISTRICT
• Xiong Xiaozhen;Kong Qinxin;Liu Guangren
• 1993 Vol. 12 (2): 162-169. 
• Abstract ( ) PDF (521KB) ( )
• In this paper,the total atmospheric water vapour and ozone content over Pingchuan district are calculated by use of the data of solar direct spectrum which observed in Pingchuan desert district during the special periods of "HEIFE" Program in Oct.1991.The calculation shows that the precision of atmospheric aerosol optical thickness is improved by use of several wave-bands solar spectrum data to determine Ångström parameters and adding cubic polynomial to fit the residual.On the basis of it,calculation shows that total ozone content is 0.323 cm-atm over Pingchuan district in Oct.,and the corresponding water vapour optical thickness is 0.238.The analysis still shows that there exists good correlation between total atmospheric water vapour and humidity at the ground,and the correlation coefficient is 0.825.Moreover,the several calculation methods of water vapour have been compared and discussed in this paper.

• CHARACTERISTICS OF THE CONCENTRATION AND SIZE DISTRIBUTION OF DESERT AEROSOL OVER HEIHE REGION
• Lei Wenfang;Ren Lixin;Lu Weixiu;Zhang Wen
• 1993 Vol. 12 (2): 170-179. 
• Abstract ( ) PDF (681KB) ( )
• Concentration of desert aerosol is usually low,in which fine particles are predominant,striking increase of dust concentration is observed during blowing dust periods,particularly that of coarse particles,which increases by more than 20 times than that on fine days,and the number of particles with diameter( D) between 2.0 and 10.0/ μm accounts 9.6% of total number of particles,much higher than that on clear days(1.9%).Moderate precipitation removal is the most effective to desert particles with D>4.0/ μm(90%),but not so effective to all particles,specially to those with D<0.4/ μm.Therefore desert aerosols with 0.5< D<4.0 μm may be transported long-distance.Movement of large-scale air mass may greatly change the concentration of desert aerosol.The diurnal variation of concentration of background desert aerosol is mainly controlled by air disperse dilution.There are three sources of background desert aerosol:global background aerosol,large range background dust and local soil dust.The measured size distribution of desert aerosol are characterized by 3-modes,which can be fitted very well by the sum of three log-normal distribution functions.

• CHARACTERISTICS OF ATMOSPHERIC TURBIDITY OVER ZHANGYE REGION
• Ma Xiaoyan;Qiu Chuantao
• 1993 Vol. 12 (2): 180-185. 
• Abstract ( ) PDF (389KB) ( )
• In this paper,the characteristics of atmospheric turbrdity have been analysed,and the reason that atmospheric turbidity increase in Spring has been revealed preliminarily by using the observational data of atmospheric turbidity from November 1990 to October 1991 at Zhangye station.The results are as follows:(1) There is a obvious seasonal variation for the atmospheric turbidity coefficient β.The largest value is in Spring,next is in Summer or Autumn,and the smallest is in Winter.(2) Fly ash by strong wind cause the β to increase rapidly in Spring.Finally,the dust content which is in the process of a dust devil is calculated.

• CALIBRATION OF THE RADIATION INSTRUMENTS AND ANALYSIS OF THE ACCURACY OF OBSERVATIONAL DATA OF RADIATION IN HEIFE
• Ji Guoliang;Jiang Hao;Hou Xuhong;Zou Jiling;Ma Xiaoyan;Zhou Xiaoping
• 1993 Vol. 12 (2): 186-191. 
• Abstract ( ) PDF (397KB) ( )
• In this paper,the calibrated results of the instruments used to radiation observation at three stations in Chinese side before and during the HEIFE and the accuracy of observational data are analysed.Results show that property of instruments used to radiation observation in the HEIFE is stable.The data observed in HEIFE close to and reach up to the international requirement in the accuracy of radiation field observation.In this paper,the correction of IR data is also discussed.

• THE CALIBRATED RESULTS OF THE NEUTRON SOIL MOISTURE GAUGE IN THE FIELD
• Liu Wei;Wang Yaoqi;Wei Zhigang;Wu Jingzhi;Gao Hongchun;Qiu Zhuantao
• 1993 Vol. 12 (2): 192-200. 
• Abstract ( ) PDF (484KB) ( )

• A STUDY OF DAILY EVAPOTRANSPIRATION RULES FOR SPRING WHEAT
• Xie Zhongkui;Lei Bo;Lan Nianjun
• 1993 Vol. 12 (2): 201-208. 
• Abstract ( ) PDF (457KB) ( )
• Using the weighing instrument-hydraulic evapotranspirometer,we have researched evapotranspiration of spring wheat in different weather conditions,different growing stages,and during the day before and after irrigating.The results show that the evapotranspiration of spring wheat is low or may be negative at night(20-08),but it increases from 08 o'clock in the morning and reaches the peak value about 16 o'clock,then decreases from 16 or 18 o'clock until minimum value about 02 to 04 o'clock at night.The evapotranspiration during clear day is higher than that during cloudy day,and the largest difference appears from 10 to 18 o'clock.After irrigating or raining the evapotranspiration of spring wheat increases to some extent.The relationships among evapotranspiration with air temperature and surface temperature are quadratic function curves at different times during a day.

• A STUDY AND DISCUSSION ON THE WATER CONSUMPTION AND WATER-SAVING TECHNIQUES FOR SPRING WHEAT IN THE ARID AREAS
• Li Shouqian;Xie Zhongkui;Lan Nianjun;Lei Bo;Ma Zhongming
• 1993 Vol. 12 (2): 209-216. 
• Abstract ( ) PDF (527KB) ( )
• In the paper,the effects of soil moisture and water consumption on the growth and development of spring wheat have been analysed and the relationships between water consumption and yield have been studied,as well as the laws of them.The results show that the critical period of water requirement appears from elongation to heading stage,the values of water consumption and the ratio of stage water consumption to total water consumption was greatest during the heading to maturity;the relationships between yield and water consumption can be expressed by using typical quadratic function curves.The suitable low limits of soil moisture are as follows:70%-75%(soil moisture/field capacity) from emergence to elongation,60%-65% from elongation to heading,55%-60% from heading to initial milking stage and 50%-55% from initial stage of milking to maturity.The causes and effects of water-saving and yield-increasing for spring wheat covered with plastic film have also been discussed.The water-saving and yield-increasing measures for spring wheat in Heihe river drainage areas,along with the suggestions for the further study,have been proposed.

• GENERAL CONDITIONS OF STUDIES ON WATER-SAVING AGRICULTURE IN WATER-LACKING REGIONS
• Li Shouqian;Ma Zhongming
• 1993 Vol. 12 (2): 217-222. 
• Abstract ( ) PDF (453KB) ( )
• In this paper,the basic theories of water-saving agriculture,water resource management,optimal water resource distribution,water irrigation techniques and all water-saving techniques,the present situation of studies on water-saving agriculture in water-lacking regions have been reviewed comprehensively.It is considered that the studies for water-saving agriculture have made great progresses,but the theories and new water-saving techniques must be further developped and perfected so as to make the agricultural produce in water-lacking regions steady and continuous develop-ping toward the water-saving,energy-economizing and high-effect.

• CALCULATIONS OF SURFACE RADIATION IN ARID REGIONS——A CASE STUDY
• Ming-Dah Chou;Ji Guoliang;Kuo-Nan Liou;Szu-Cheng Ou
• 1993 Vol. 12 (2): 223-234. 
• Abstract ( ) PDF (891KB) ( )