Soil heat flux plays an important role in energy flux exchange between land and atmosphere, especially in arid and semi-arid region. Based on soil heat flux at Zhangye National Climate Observatory, the diurnal variation of soil heat flux and the relationship between that and radiation flux are analyzed under different weather conditions for clear, cloudy and rainy day.The results show that the soil accepted heat from the air on clear day, on the contrary, the output heat of soil exceeded the input on cloudy and rainy day. In addition, most values of soil heat flux are negative in autumn and winter season, and positive in spring and summer .
Based on five - layer wind speed, air temperature, humidity and vapor p ressure of the gradient tower of Zhangye National Climate Observatory built in 2007 from Sep tember 2007 to August 2008, the percentage of missing value was calculated, and the climate characteristics of Zhangye in different seasons were also analyzed. The reliability of data from the gradient towerwas checked by comparing with some other observational stations.
Ground - based meteorological observation is essential for understanding the relationship between alp ine glacier and climate change, especially in remote regionswhere in - situmeasurements are extremely limited. Themeteorological factors, including air temperature, wind speed and direction, atmospheric water content, were measured over the accumulation area on the East Rongbuk Glacier, Mt. Qomolangma ( theMt. Everest) at elevation of 6 560 m. Measurements were conducted using an automatic weather station (AWS) fromMay 1 to July 22, 2005 ( sp ring - summer period) and from October 2, 2007 to January 19, 2008 ( autumn - winter period). The variational trend of air temperature and atmospheric water contentwere nearly similar at both the measurement site and Dingri meteorological station by analyzing the observations, and this result testifies the rationality of the observed data on the extremely difficult conditions. Mean monthly air temperature ranged from - 11. 3 ℃ inMay to - 3. 4 ℃ in July, 2005 and from - 11. 3 ℃ in October,2007 to - 19. 0 ℃ in January, 2008 at the AWS site on the East Rongbuk Glacier in theMt. Qomolangma region. Near - surface the mixing ratio of water vapour increased from 1. 4 g/kg inMay to 5. 4 g/kg in July of 2005 after onset of the Indianmonsoon, while it decreased very slowly from 1. 4 g/kg in October of 2007 to 0. 5 g/kg in January of 2008 when the westerlieswas dominated in the region.Surface wind characteristics were strongly controlled by two major synop tic circulation regimes: the Indian monsoon regime in summer and the westerlies in winter. At the AWS site on the East Rongbuk Glacier, north or northwestwinds p revailed and mean monthlywind speed ranged from 7. 1 m / s in October, 2007 to 14. 2 m / s in January, 2008 with the extreme value up to 35 m / s. South or southeast winds p redominated after the onset of the southwesterly Indian monsoon with relatively low wind speed in summer, ranging from 6. 9 ms- 1 inMay to 2. 2 m s- 1 in July, 2005.
The photo—·physiological characteristics of Achnatherum splendens both in the enclosure an d the grazing pasture were moni-toted in Anxi．Th e results showed that the diference was significant between them．Th e air temperature and leaf temperature were rela．tively lower and the relative humidity Was higher in the enclosure compared with those in the grazing grassland．These indicated that the environment of grass growth Was greatly improved by enclosure means．At the same time，there Was higher photosynthetic rate of Ach-hat．rum splendens in the enclosured grassland．This Was beneficial to growth of grass and accumulation of dry matter．
An observation and analysis on microclimate in greenhouse were carried out in semi一arid region which lies in Loess Plateau. "hhc results show that the temperature and the relative humidity in different height in greenhouses were different, that is to say, the temperature at 1.5 m height was higher than that at() .> m，and the relative humidity at 1.5 m height was lower than that at() .> m，thus, there was a microcnvironment of the lower temperature and higher RH at() .5 m height compared with that at 1. 5 m. IW ring cucumbers growth period，the temperature in greenhouses maintained around 12一23. 5 C，R H ex- cccdcd 77. 3%in lower layer. Additionally, the survey shows that downy mildew occurred in every growth stage from seeding to bearing period，and the degree of disease in under part of the plant was more serious. So the conclusion on optimum climate condition of occurring and spreading of disease was the lower temperature and higher RH. At last, we brought forward the in- tegrated control measure.
