The characteristics of surface air temperature，snow depth and other climatic elements gre analyzed on the basis of outputs from the Exp．1％C02 in which the atmospheric C02 concentration is increased by l％per year and Exp．50yrs in which the observed increasing atmospheric aerosol andC02 concentrations are used．We discussed the effects of the aerosol ou climate change over the Tibetan Plateau．The results show that there exists asignificant elevation dependency of surface climate warming，i．e．the warming trend increases with the elevation in a higlI—altitude region and its surroundings in spring，sUnllller，autmnn and winter in Exp．1％C02．For example，the linear warming trends of surface air temperature reach 0．29，0．36 and 0．50℃／10 a for 3 zones with elevations in the milge of 1．5—2 km，3—3．5 km and 4．5—5 km，respectively．With the climate wanning over the Tibetan Plateau，the snow depth decreases，which is nlore markedly at hish—altitude regi∞than its surroundings in Exp．1％C02．In Exp．50yrs，however，the linear warming trend of surface air temperature is weak，though it is prominent at high elevations than at low elevations in the Tibet Plateau and the surroundings in spring，summer and autumn over Tibetan Plateau．In winter。the trend of surface air temperature is 0．02，一0．03 and一0．13℃／10 a for 3 zones with elevations in the range of 1．5-2 ian。3—3．5 iun and 4．5—5 ian，respectively．The relatively weak warming revealed in the E】【p．50yrs may be related to the increasing atmospheric aerosol concentration originatedfrom South and East Asia during the past decades．

Using 1961一2000 dekadly precipitation from 76 weather stations in the Qinling mountains and the surroundings and largescale grid winds at 850 hPa from NCAR/ NCEP ,the climatology spatial一temporal characteristics of the precipitation and their as sociations with the atmospheric circulation have been analyzed in this paper. The results show that the flood season for the 40一year average occurs in the period from the third dekad of June to the first dekad of October ,during which there are two peaks of precipitation ahe first dekad of July and the first dekad of September. The rainfall in the south side of the Qinling mountains is obviously higher than that in the north side ,although the interannual variations of both are basically consistent. The Qinling mountains and the surroundings are mainly controlled by the southwesterly monsson in the flood season ,e}ecially in the midsummer ,but are mainly impacted by the southeasterly monsoon in the early autumn. The composite analyses show that when theprecipitation is more(less)than normal ,the southerly wind at the south boundary of the study area is often stronger(weaker) than normal in the flood season. By the regression analyses ,it is found that the increased rainfall in a dekad in the flood season generally corresponds to the strengthened Somali
Jet and southwesterly monsoon in the dekad with a two一dekad lead ,and an anomaly anticyclone near Taiwan in the one一dekadlead
dekad and the same dekad.