Based on conventional data, automatic weather stations observations, Doppler weather radar products, satellite image and NCEP/NCAR daily 6 h reanalysis data, the environmental conditions and storm features of a regional thunderstorm gale on July 9th 2017 were analyzed. The results show that the thunderstorm gale occourred under the influence of upper northwestern flow, the lower vertical wind shear, high temperature lapse rate and the accumulation of abundant energy in the lower layer were favorable for its occurrence. Ground cold front, dry intrusion and mesoscale convergence line were triggering mechanism. The organized band was composed by scattered convective clouds in front of the cold front along the surface mesoscale convergence line. At the first and the second stage, the gale with wind force scale greater than 10 occured at the mature stage of thunderstorm clouds, it was mesocyclone type in the first period, the mesocyclone appeared first in the middle layer, and then developed to the lower and higher layers, the thunderstorms broke out when the bottom of the mesocyclone dropped to 2.2 km. At the second stage, it was mainly the gale type caused by the strong inflow behind the thunderstorm cloud at low altitude ( 1.0 km). The gale with wind force scale greater than 10 at the third stage appeared in the extinction period of thunderstorm clouds, which was formed by strong outflow in front of thunderstorm clouds.
Over the past 50 years, temperature in the Northwest China p resented a significant rising trend, while p recip itation change was different in different p lace. Warming and drying trend is evident in the whole Northwest China, but the local appearswarming and wetting phenomenon. With the global warming, glaciers retreat and snow line rises, permafrost melts, wetlands degradation, lakes shrink, river flows decrease, water resource becomes scarcer, and eco - environmental degradation. According to IPCC forecast results, the climate warming trend in this region in the future will be more p ronounced. The countermeasures to p rotect the ecological environment, imp rove the comp rehensive climate change monitoring system, launch specific research on the key regional climate changep rocesses, and other suggestionswere put forward.
Based on the summarization of the former similar researches about land surface dewfall, this article systematically discusses dewfall’s formation mechanism and analyzes the relation between dewfall and climatic aswell as environmental factors, such as temperature, humidity, windspeed, cloud, topography, and so on. The ecological and climatic effects and biochemics effects about land surface dewfall are discoursed also, and some p roblems in the p resent research on dewfall are pointed out finally.Key words: dewfall; formation mechanism; ecological and climatic effects
The spatial distribution ofwater resource shortage in China is summed up from the p ractical condition and sustaining devel2 opment angles. The actuality and trend ofwater resource are reviewed, the characteristic ofwater cycle and water resource utilization in arid region ofNorthwest China are analyzed. And research advances on water cycle and effective utilization ofwater resource in arid re2 gion are summarized, the scientific countermeasures about effective utilization of water resource in arid region are p reliminarily dis2 cussed. Finally, some important scientific issues aboutwater cycle and effective utilization ofwater resource in arid region ofNorthwest China are put forward.
By analyzing spectrum characteristics of snow，clouds and diferent land covers in the Qilian Mountain region based on MO-DIS data from July 2003 to March 2005，a new method for snow discrimination is presented on the basis of former researches，which combined NDSI(Normalized Diference Snow Index)and band 18，band 3 1 of MODIS to discriminate snow from clouds，saline，ice，desert，etc．with a step—by—step approach．Both result analysis and examination show that snow in the Qilian Mountain region canbe efectively discriminated by the method of this article．
At first，the meaning of the water transfer processes(wTP)over land Surface is set forth and its uniqueness in arid and semi—arid region is discussed in this paper．Later，the sensitivity ofthe ecology and soil characteristics in arid and semi—arid region to the WI’P is presented．The domestic and foreign research advances on WTP is summed also．Finally，the deficiency on the WTP study in arid and semi —arid region is analyzed and the way to research the珊there is suggested．
The hailstorm occurred on July 6 to 8, 2003 over the northeast of Qinghai-Xizang plateau was simulated by using MM5, and its meso-scale circulation background and local convective cells characteristics were analyzed based on simulated data. The results show that: (1) This hail fall process was simulated well by MM5; (2) Warm humid air from south at lower level and cold dry air from northwest at middle and upper level resulted in this weather process, and the factors such as local terrain, etc. were important to this event; (3) Convective cells formed at high altitude plots firstly and then spread to lower altitude area, and the speed and directions of cells’ spread depend on terrain factors and upper level wind
based on the mean daily temperature data in spring from 1961 to 2000，using empirical orthogonal function complex empirical orthogonal function(CE<)F)，fractal dimension，and wavclet analysis methods, the spatial and temporal evolvement of spring cold weather intensity in Chinese loess plateau was analyzed in this paper. Results show that the spring cold weather intensity decreased approximately from north to south, and also there was a gradient from cast to west;the linear decreasing rate of the spring cold weather intensity in the middle of the plateau was bigger than that in the peripheral，and the changing tendency was remarkable in March and April;there was periodic oscillation of the spring cold weather intensity change，which were about 2一}I a in March，3一} a in April，2一} a and 6 a in May, respectively. 'hhe spring cold weather in- tensity was weakest in 1990x. "hhe strongest period of spring cold weather in March，April and May, and the distribution was different in each month. "hhe spring cold weather intensity change in April had a transition in 1980，and then it decreased obvi- ously. 'hhe fractal dimension increased gradually from March to May, the changing complex degree of the spring cold weather intensity increased at the same time. "hhe big amplitude area of spring cold weather was in the center of the plateau. "hhe change information flew to cast in the west and southwest in the cast of the plateau.
Based On Chlna n1PtPOTOlOg1C8} Lln(1PTta}lng adVariCement StTatagPln} by analyZlng the featIIreS Of Weather and Climate and C1TCLnnStanCe and the aCh18.}lty Of Climate OhSClvlng System In nOrthWCSt TPglOn} the paper has pTCSented a lnltlal }TO}PCt Of ATld Ch- mate Observing Systen ( ACOS)，Wh1Ch COriS1StS Of 4 parts Of the gTOllnd-haSe OhSPl"Vlng} the a1T-haSe (leteetlng} the Space-haSe mOnl- tOTlng and the 1T1fOTmatlOn tTanSmlttlng and ShaClng. T11eTe are 3 layers Of Weather StatlOriS} eCOlOg1Ca1 and Climate eXpeTlment StatlOriS and land一、urface process experiment bases in the ground-base observing part. The aim of Arid Climate Observing Systen ( ACOS)， Centered On atnlOSphere} 1S t0 CaITy Ollt COmpOSlte three-dlmenSlOna1 OhSClvatlOn On Jr-Sphere Of atnlOSphere} by击OSphere} CryOSphere} lithography and biosphere and interaction among them.
The fact of global warming and the effects on ecological environment，society and economy in Gansu province in the background of global warming are analyzed with the interrelated materials in this paper. The countermeasures against climate change andsustainable development are shown too.And those，to Gansu province，can be summed up as two primary problems.First is water problem.Water problem is primarily to utilize reasonably，manage efficiently，save water，exploit and utilize water resources by precipitation enhancement over the Mountain Qilian. Second is sand problem.The problem is crucially to hold back the process of desertification.As this paper’sview，this holding back can be realized by the optimum project for recovering vegetation which would be abstract edby quantitatively calculating the categories distribution，run and carrying capacity of local forest and grassp lanted by using Regional Climate-Ecology Mode according to ecological environment sincluding terrain，physiognomy，climatehydrology，soil and so on.
The orientation ,current situation ,chance and challenge of special meteorological institutes(SMI) of China Meteorology Agency(CMA) were analyzed Meanwhile ,some important problems on how to establish perfect state special meteorological science and technology innovation system were put forward experimentally according to the view of science acteristics of SMI. Moreover .the practical experience of establishing arid一meteorology science worker as well as the }ecific char and technology innovation system.which was based on the reality of Institute of Arid Meteorology ,CMA .was elaborated
Atmospheric chemistry is an booming discipline in atmospheric sciences. Its researches started one hundred years ago.but the observation of atmospheric owne and theoretical researches in owne actinic chemistry are milestone. Many facts and phenomena in atmospheric chemistry field are not understood at present .especially some problems on sinks.sources and spatial and temporal distribution of some atmospheric trace elements and their migration .transfer and global cycle is necessary to more deeply and widely observe and research.
After reviewing the history of development and summarizing the current scientific advances of the stu勿on atmospheric boundary layer meterology .the key scientific problems faced in the future about this field werepointed out .it also gave several sug- gestionsforfuture development direction .At t he same ti me .the ideas and methods of the stu勿were demonstrated as well.
