The sand－dust storm weather occurred on April 24，2010 in the middle of Hexi Corridor was studied．The results show that the strong cold air from the northwest route resulted in this heavy dust storm，it occurred during the process of 500 hPa circulation situation transition from the latitudinal to longitudinal direction．The continual temperature rising provided the favorable thermal condition for sandstorm．The upper and lower level jet stream provided the dynamical condition for it．The exist of dry－warmer area was an omen for its occurrence and it provided abundant sands．The unstable atmospheric structure with warm lower and cold upper was good for the momentum transmitting downwards of the strong wind in upper air．The daily forecast indexes and equations under the different weather conditions were summarized based on the meteorological data from 1969 to 2004 in the middle of Hexi Corridor and the numerical forecast products from 1986 to 2004．The now－forecast indexes were modified and complemented，and it played a well role in the forecasting work of dust weather．
Based on daily precipitation data from five stations in Wuwei(located in east of Hexi Corridor)from 1960 to 2009，the spatial and temporal distribution of precipitation over 10 mm(daily precipitation≥10 mm)was analyzed systematically in this paper．The results show that precipitation over 10 mm was more obviously in south part than that in north of east Hexi Corridor．Annual variation of precipitation days over 10 mm was not consistent in each region，and it presented increasing trend in Tianzhu，Yongchang and Minqin，but decreasing trend in Liangzhou and Gulang．The rainfall(precipitation over 10 mm)weather occurred maily in April to October，especially in July and August．Precipitation over 25 mm only occurred in May to September，and the annual precipitation correlated with occurrence times of precipitation over 25 mm．The circulation situations which resulted in precipitation over 10 mm in east Hexi Corridor were Xinjiang cold trough moving to east and south，and southwest air current，and the abundant water vapor condition，the intense lifting movement and the unstable energy were essential conditions．Based on data of ECMWF numerical forecast grid field，the factors were initially selected with Press criterion and selected accurately with stepwise regression forecast method，the forecast equations for precipitation over 10 mm were established with optimal subset regression．The most superior significance forecast equations of precipitation over 10 mm in each region were determined finally with the CSC double grading criterion．Forecast marginal value and qualitative forecast of precipitation over 10 mm were determined using principle that the fitting and the summary rate were the biggest simultaneously．
Based on daily meteorological data of sunshine hours，wind speed，air temperature and relative humidity at 80 weather stations from 1961 to 2008，the human comfort index in Gansu province was calculated and its spatial and temporal distribution was analyzed also．The results show that human comfort degree ranged from cool to comfort in Gansu，the cool days were 60 percent and comfort days were 40 percent of the whole year and there were no uncomfortable days in a year．The human comfort degree kept a higher level that the comfortable days were nearly six monthes in most places except for Gannan Plateau．The most comfort regions for human living were the southeastern part of Gansu province，including Wudu，Wenxian，Maiji，Tianshui，and the eastern and middle part as well as Hexi Corridor of Gansu province．In addition it indicated that comfortable days increased due to climate change．
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.
According to the standards of the nationalwind power plant and wind energy resource assessmentmethodology, the spatial distribution ofwind energy in Jiuquan ofGansu Provincewas revealed by using different layer informationmeasured by six anemometer towers there, imultaneously, the variouswind parameterswere calculated and analyzed in the paper, which is useful for furtherunderstanding and application ofwind power in Jiuquan region.
Homogeneity of the climate data is p recondition on studying climate change. This paper used SNTH technique to test the homogeneity of climate series of Lanzhou meteorlogical station, and the inhomogeneity test on meteorological factors such as p recip itation, average temperature, maximum temperature, minimum temperature, average wind speed and sunshine hourswas conducted; meanwhile, the reason was analyzed based on the station history files and metadata information. The results show that inhomogeneity existed in time series of p recip itation, average temperature, maximum temperature, minimum temperature and sunshine hours, and the main reasons were relocation of station, changes of instruments, changes in statistic methods and urban heat island effect.
on the daily average temperature of 150 weather stations in northwest China from 1961 to 2003, the characteristics ofthe < 0 ℃ , > 0 ℃ and > 10 ℃accumulated temperature in response to climate change have been analyzed by using climatic tenden2cy coefficient and climatic tendency quotiety. The interannual change of < 0 ℃ , > 0 ℃ and > 10 ℃ accumulated temperature have been analyzed based on the time coefficient from EOF bymeans ofwavelet analysis andMann Kendallmethod. The results show that < 0 ℃, > 0 ℃ and > 10 ℃ accumulated temperature p resented increasing trend in Northwestern China, and the mean climatic tend2 ency quotieties of < 0 ℃ negative accumulated temperature, > 0 ℃ and > 10 ℃accumulated temperature are 52. 9 ℃/10 a, 50. 7℃/10 a, 49. 3 ℃/10 a,respectively.
The new generation of "the synthetical system of operation and service on the northwest drought monitoring and fore is a synthetical system of operation service which has good physical foundation，stronger monitoring, prcdicting,and service abilities, higher automation degree and local characteristic of the northwest region. Relying on the short一term weather forecasting, this system gathers the weather information collecting, processing and information saving for an integral whole, and takes full advantage of the Internet technique and previous systems, data and information，takes up the systems and pro- ductions of the other sul〕一special subjects in the item，so that it saves the great capacity of computer space，avoids many rc- pcated labor, and it brings into play the positive function in the usually monitoring and forecasting service in recent years.
Using the microsoft access database system, a database of sandstorm in arid region in Northwest China has been created. We designed system of data mining (data mining machine), data maintaining ,data querying and data interface by C/S programming structure under database environment. When normal user doesn't know data format ,the data mining machine can achieve data query- ing and statistics according to any condition by visual interface ,and process data by all kinds of algorithms and come up with user needful data SeqLIenCe. Th1S System Can Olltpllt qLICrylng TCSLI1tS by graph ,teXt flle ,mapplng flle and SO On .The new data can he ap- pended by the data maintaining system easily.
In this paper, the distribution, causes and characteristics of geological calamity in Lanzhou city were analyzed, and the temporal and spatial distribution of geological calamity and intense rainstorm, the weather systems and the relation between geological calamity and rainstorm intensity were studied mainly. The critical precipitation index were set up and defending countermeasure was given, and these will he necessary for developing prediction and warning of geological calamity in Lanzhou city.
A study was carried out about the duration time，scop e，and intension of the 2002 summer and autumn continuous drought in Cransu，which long duration time and heavy intension scarcely appeared in recent 50 years. The causes of continuous drought were ainly depended on that Westerly circumfluence，and the High ridge over Baikal and Northwestern Pacific very strong ;the trough ver Southern Indian Peninsula weak; the sea levelpressure departure on the high side;sea surface temperature anomaly and El Nino ccurring. All those above together forced into continuous drought in Cransu Province. These results were significantly to establish the reventing and reducing calamities rules and valuably to short一term climate forecast.
