In order to study the main geographical influencing factors of summer precipitation and the best interpolation method of precipitation in the complex Sichuan Basin, especially the mountainous area around the basin, Sichuan was divided into four regions by using cluster analysis based on 10 years (2010-2019) summer precipitation data of 157 automatic meteorological stations in Sichuan Province. The correlation analysis and the multiple regression analysis methods were used to screen out the geographical influencing factors of precipitation in each region. In addition to using the cooperative Kriging interpolation method, the traditional interpolation method is used to compare. The interpolation results are tested by cross-validation method. The results are as follows: (1) The geographic influencing factors that can be used to characterize the summer precipitation in Sichuan were mainly longitude, latitude, altitude, slope and normalized difference vegetation index. (2) Due to the diversity and complexity of the topography in Sichuan, the effect of precipitation interpolation after the division was better than that before the division.(3) When the number of precipitation influencing factors in the selected area was moderate, the coKriging interpolation method was better, and when the number of precipitation characterization factors in the selected area was single or too many, the radial Basis function interpolation method or empirical Bayesian Kriging interpolation method were more effective.

In 2008 and 2005, there were two typ ical freezing disasterweather events occurred in Hu’nan Province and resulted in severe damages due to their powerful intensity. In the paper, we made comparative analysis from charactereristics and formation causes of these two weather events and pointed out the forecast factors for freezing weather, which can further imp rove forecasting capabilities of freezing weather in Hu’nan Province.

The predictionmodel for the highestand lowest temperature is established by the CMSVM regressionmethod based on ECMWF data and the extreme temperature observations from 8 automaticweather stations inQingyang ofGansu Province from 2003 to2007.The effect test in 2008 operation forecast indicated that the rate ofaverage forecastaccuracy is64% and 71% for the highestand lowest temperature in 5 days, which has the good instruction for the real-timeweather service. The forecast accuracy rate of the highest and lowest temperature decreased with the forecast time increase, and the accuracy rate for the lowest temperature is higher than thatof the highest temperature. The forecast effect for the lowest temperature is better in spring and summer than that in autume and winter, but it is opposite for the highest temperature. The absolute and the average forecasterrors for the highestand lowest temperature are added with the forecast time increase, and the absolute forecasterror for the highest temperature is bigger than thatof the lowestbut the average error is close and positive. The forecast effect test in Septemper of 2008 indicated that the forecast values presented the similar trend to real time observations for the highest and lowest temperature.

By using thelatest data obtainedfromthe 80 m observingtowerformeteorolo~calfactors detectinginthe hinterland ofTaldi·makan Desert。the evolution characteristics of the wind velocity，temperature an d humidity profiles near the surface layer there on a cloudy day(A 1 2，2006)were analyzed in detail，and these profiles were compared with those ofthe typical sunshiny day there．Re·suits are as follows：(1)On cloudy day，the value of wind speed is increasing with height at night but its change doesn’t obey the loga·rithmic law，it grows at a faster rate；in the daytime the wind spe ed is small，the distributions of wind velocity profiles above and below 10 m near the surface layer are rather diferent at each o~ervational time；(2)Observed temperature profiles on cloudy day age classi·fled into four types：radiation coling at night。transition from night to daytime in early morning，insolation in the daytime，transition from daytime to night，respectively，they are similar to those of sunshiny day；(3)There is a minimum in spec~c humidity profiles，a·beve the height where the minimum appears the specie humidity rises with height increase and appears a”moisture inversion”phe·nomenon，and below that height the specific humidity rises with height decrease．

Desertific;ation is one of the most serious ec;ologic;al} social and economic; problems in arid and semi一arid regions in the con-
temporary world.  Based on referring to a large amount of literature we have narrated and(ommented the concept of desertification in
detail and its  connotation from time spac content  landscape  development tendency and results of sandy desertification in this arti-
cle and have particularly outlined the domestic and foreign desertific;ation monitoring appraisal target system}graduation and its distri-
bution in the world. On one of the focal arguments point of the(auses of desertification} we have synthesized various viewpoints and fi-
nally summarized as natural reason and artificial reason such as drought climate, gale and unreasonable human being's”six excesses"
activities.  Simultaneously controlling methods, basic  we have outlined the interaction ways of desertific;ation and some
Between global warming and desertification. In the end， the preventing and questions like these have also been summarized systemically

In this paper,.the spatial and temporal characteristics of drought in China are the analyzed. On the basis of the main factors of the influence of China climate anomaly .the causes of drought are also studied.  It is shown that the causes of formation are mostly the
global and regional climate warming .the inter一annual and decadal oscillation of the main factors.