Variation Characteristics of Thermal Resources in East Hexi Corridor in Recent 50 Years

[Objective] The aim was to study variation characteristics of thermal resources in east Hexi Corridor in recent 50 years. [Method] Using the daily average air temperature data from 5 meteorological stations in east Hexi Corridor from 1959 to 2010, the variation of accumulated temperature steadily above 10 and 0 ℃, lasting days, the beginning and ending day were summarized, and then the variation characteristics of thermal resources under the background of climate warming were analyzed. [Result] The air temperature increased continuously in east Hexi Corridor, and the climatic trend rate of the annual average air temperature was 0.34 ℃/10 a, more significant than any other region in China. And it was well correlated with the thermal resource indexes such as the accumulated temperature steadily above 10 and 0 ℃, and their lasting days, and the beginning and ending day. Climate warming had made the accumulated temperature steadily above 10 and 0 ℃ increased significantly in east Hexi Corridor widespread. The accumulated temperature steadily above 10 and 0 ℃ had increased significantly. The lasting days of accumulated temperature steadily above 10 and 0 ℃ increased significantly too. The delay of ending days was more significant than the advancing of beginning days. [Conclusion] These changes in thermal resources were conductive to increase food production and maintain the stability of food production in east Hexi Corridor.

Relative Ecological Value of Major Plants in Minqin Desert Area

This paper analyzed relative ecological value of several major plants in Minqin desert grassland using layered projection of plant canopy. The results showed that ecological functions of natural Nitraria tangutorum and Ephedra sinica woods of a unit area were much better than those of artifi cial Haloxylon ammodendron woods, relative ecological value of N. tangutorum, E. sinica and Artemisia desertorum were much higher than that of artifi cial H. ammodendron woods. Layered projection explains clearly the ecological functions and relative ecological value of desert vegetation of the same coverage. It is inaccurate to indicate wind prevention and sand fi xation of desert vegetation in deserts using ecological function service value and ecological niche calculated on the basis of two-dimensional vegetation coverage, but three-dimensional projection degree should be applied to indicate ecological functions and relative ecological value of vegetation. Application of layered projection of plants in calculating ecological functions and relative ecological value of desert plants(vegetation) is the innovation point of this research.

Response Characteristics of Climate in the Shiyang River Basin to Global Warming

Meteorological data of 5 weather stations in the Shiyang River Basin on the eastern section of Hexi Corridor from 1961 to 2014 were analyzed using statistical analysis techniques such as linear trend and variance signifi cance test. The results showed that as the low temperature rose generally, temperature in stations nearby desert showed higher increase rate; annual extreme maximum temperature in stations nearby mountains showed more signifi cant increase, and annual extreme minimum temperature in stations nearby desert showed more signifi cant increase, and the increase tendency of extreme minimum temperature was more obvious than that of extreme maximum temperature; annual extreme maximum temperature in stations in desert showed higher instability; instability of annual extreme minimum temperature in all sampling points increased, and showed no obvious regularity between desert and mountain.

Study on Cold Wave Weather in Hexi Corridor from March 12 to 14 in 2011

[ Objectivel The aim was to study the cold wave in Hexi Corridor in 2011 and to summarize report experience. [ Method] Routine obser- vation data and Ecmwf numerical product were used to analyze the circulation background, causes and influential system of Hexi Corridor from March 12 to 14 in 2011. [Result] The cold wave in the mid-high latitude circulation in Northern hemisphere transited from radial type to warp type. High early basic temperature was the premise of cold wave. Drastic ground movement was the direct cause of cold wave. Prevailing cold advection was one primary cause of temperature reduction. Radiation in sunny days also posed certain influences on regional temperature. Factors weakened the gale were as follow, cold air largely in north area, cold air moving southeastward in diffusion, front passing early, upper and lower air conver- gence against the convection development and slow wind in high and lower air. [ Conclusion] The study provided important references for further enhancement of cold wave and gale report.

Diurnal Variation Characteristics of Precipitation in the Shiyang River Basin of Northwest China in Summer

Based on the hourly precipitation data from 32 regional meteorological stations and 5 automatic meteorological stations in summer (from June to August) over the Shiyanghe River basin from 2009 to 2013, we analyzed the diurnal variation characteristics of precipitation over the Shiyanghe River basin, by using four precipitation indices (hourly precipitation, hourly precipitation frequency, hourly precipitation intensity, and different duration precipitation). The results show that the spatial distribution of hourly precipitation, hourly precipitation frequency in summer declines from upstream to downstream over the Shiyanghe River basin because of geographical position, altitude, latitude and weather systems, and the spatial distribution of hourly intensity is complex. The precipitation, the precipitation frequency and the precipitation intensity over the Shiyanghe River basin present a diurnal pattern of double-peak distribution, with the peak periods at 01:00-09:00 and 14:00-23:00, strong precipitation present single-peak with the peak period at 14:00-23:00. Total precipitations and precipitation frequencies of 1 - 3 h short-time rainfall are more than long time rainfall continued more than 10 h over the Shiyanghe River Basin. The short-time rainfall continuing within 1 - 6 h often occurs from afternoon to evening, the long time rainfall continuing more than 6 h often occurs from evening to early morning or late afternoon to evening.