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24 December 1995, Volume 14 Issue 4   
  • NUMERICAL EXPERIMENTS FOR THE EFFECTS OF THE RISING OF THE TIBETAN PLATEAU ON THE FORMATION OF ASIAN SUMMER MONSOON
  • Wu Chisheng;Wang Anyu
  • 1995 Vol. 14 (4): 425-433. 
  • Abstract ( ) PDF (331KB) ( )
  • Five sets of numerical experiments were performed by using a five-layer limited area primitive equation model Among them,one is for real topagraphy with mean height of 4000 m;and the others are for the heights of 1000 m,2000 m, 3000 m, 3500 m,respectively Their results were compared each other It was shown that: (1) The atmospheric heat source over the Tibetan Plateau and its southeast neighbourhood strengthened with the rising of the Plateau Especially,when the mean height of Plateau was rised from 3000 m to 3500 m,the intensity of the heat source increased significantly and correspondently,the Asian summer monsoon circulations were changed obviously (2) When the mean height of Plateau was rised to 3 500m,the South Asian high in the upper troposphere appears,and the tropical easterly to the south of the high center was strengthened considerably Meanwhile,the low-level thermal low over the Asian continent moved westward to over the Plateau rapidly If the Plateau rised higher than 3 500m,the monsoon meridional cell,with the ascending branch over the Plateau and the two descending branches to the north and south sides of Plateau respectively,was seted up completely As a result of adding of the Plateau monsoon to the monsoon caused by the thermal difference between sea and continent,the Asian summer monsoon was strengthened considerably (3) In response to the rising of Tibetan Plateau,the distribution of rainfall was also changed The positive (increasing) and negative(decreasing) rainfall centers were located in the southeast side of the Plateau and the east coast of the Bay of Bengal,respectively.
  • CHARACTERISTICS OF LONGWAVE RADIATION OVER THE QINGHAI-XIZANG PLATEAU
  • Ji Guoliang;Jiang Hao;Lu Lanzhi
  • 1995 Vol. 14 (4): 451-458. 
  • Abstract ( ) PDF (273KB) ( )
  • In this paper, characteristics of the upward, downward longwave radiation and surface effective radiation over the Qinghai-Xizang Plateau are analysed by using the upward and downward longwave radiation data observed at Wudaoliang in the northern Qinghai-Xizang Plateau from September 1993 to August 1994, the longwave radiation data observed at Lhasa, Nagqu, Gerze and Garze stations in the Qinghai-Xizang Plateau from August 1982 to July 1983, the longwave radiation data in Qinghai-Xizang Plateau Meterorological Experiment (QXPMEX)from May to August 1979 and radiation data in HEIFE of 1991.The result s show that over the Qinghai-Xizang Plateau, the surface effective radiation is larger than that over the plain because the downward longwave radiation is small.The annual variation of surface effective radiation is large in summer and small in w inter over the western Plateau, large in w inter and small in summer over the eastern Plateau, large in spring and autumn and small in w inter and summer over the northern Plateau.The role of surface effective radiation in the surface radiation balance is larger than the surface abledo over the Qinghai-Xizang Plateau.