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《Arid Land Geography》 2008-02
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Intra-annual inhomogeneity characteristic of atmosphere precipitable water over the Northwest China

YANG Jin-hu1,2,WANG Peng-xiang1,BAI Hu-zhi1,YAO Yu-bi2(1 Key Laboratory of Arid Climate Change and Reducing Disaster of Gansu Province,Key Open Laboratory of Arid Climate Change and Reducing Disaster of China Meteorological Administration,Lanzhou Institute of Arid Meteorology,China Meteorological Administration,Lanzhou 730020,Gansu,China;2 Meteorological Bureau of Dinxi City,Dixi 743000,Gansu,China)  
Using NCAR/NCEP reanalysis data on wind fields,specific humidity fields and surface pressure fields from 1954 to 2004,month by month atmosphere precipitable water was calculated in the Northwest China,then its intra-annual inhomogeneity was analyzed in terms of the concentration degree and concentration period.The results show that consistent anomalous spatial distribution of the atmosphere precipitable water concentration degree(qcd) and period(qcp) is main distribution characteristic in Northwest China,and its westerly belt region is the most anomaly region.It is proved that the atmosphere precipitable water concentration degree and period have 2-4a and 6-8a high-frequency fluctuation periods,at present its concentration degree is lean towards becoming strong and concentration period is lean towards moving ahead.It is found that atmosphere precipitable water has prominence difference in anomaly years of concentration degree,annual average atmosphere precipitable water is liable to be much more in anomaly strong years,and vice versa;but atmosphere precipitable water has not prominence difference in anomaly years of concentration period.Furthermore,it is also found that in anomaly strong years of atmosphere precipitable water concentration degree,southwest monsoon water vapor transportation is higher than that of average year in the southeast of the Northwest China,and in the other areas westerlies water vapor transportation is higher than that of average years;because of plenitudinous water vapor provision,thus atmosphere precipitable water is more than that of average years in Northwest China,whereas in anomaly weak years of atmosphere precipitable water concentration degree,southwest monsoon water vapor transportation is lower than that of average years in the southeast of Northwest China,and the other areas westerlies water vapor transportation is lower than that of average years;because of exiguous water vapor provision,thus atmosphere precipitable is no more than that of average years in the Northwest China.
【Fund】: 科技部科研院所社会公益研究专项“中国干旱气象灾害监测预警方法研究(2004DIB5J192)”;; 干旱气象科学研究基金项目(IAM200609)共同资助
【CateGory Index】: P426.6
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