摘要
The synoptic circulation features, moisture transport and water vapor budgetover the central and eastern China during 21-31 July 1998 are studied by utilizing the daily 1° x1° data of the National Centers for Environmental Prediction/National Center for AtmosphericResearch (NCEP/NCAR) and observational data of 24-h rainfall recorded by meteorological stations inChina. The results clearly indicate that a dew-point front (it was revealed by Gao et al. 2002),marked by a large horizontal moisture gradient in the mid-lower troposphere, located near theperiphery of the West Pacific subtropical high (WPSH), can conjugate with the Meiyu front, and forma predominant double front structure (the Meiyu front system), which is related to the intenserainfalls over the Yangtze River Basin in China. The precipitation over China for 21-31 July 1998was characterized by a narrow intense rainfall zone over the Yangtze River Basin, and it was againstthe southern side of the Meiyu front and bounded by the dew-point front. The water vapor transportand budget over three domains, corresponding to the location of the dew-point front, the passagewayof the Meiyu front and the dew-point front, and the Meiyu front, respectively, bounded by20°-25°N, 25°-30°N, and 30°-35°N, and 105°-121°E, indicate that the convergence of themoisture flux within the passageway is mainly due to the southwesterly and southerly moisture inflowacross the dew-point front. Persistence of the water vapor gradient located at both sides of thepassageway is correlated highly with the southwesterly and southerly moisture inflow and itsconvergence in the passageway. Water vapor budgets over the three domains indicate that the watervapor is mainly converged at lower levels, and is uplifted from low levels to upper levels throughconvective transport. The passageway has net water vapor budget and is the area corresponding to themost water vapor transport and convergence during the analyzing period. The diagnosis resultsfurther manifest that the water vapor mainly comes from the Indian Ocean and the Pacific, and thatthe water vapor convergence of regional torrential rain is also provided by the semi-hemispherescale water vapor transport.
The synoptic circulation features, moisture transport and water vapor budgetover the central and eastern China during 21-31 July 1998 are studied by utilizing the daily 1° x1° data of the National Centers for Environmental Prediction/National Center for AtmosphericResearch (NCEP/NCAR) and observational data of 24-h rainfall recorded by meteorological stations inChina. The results clearly indicate that a dew-point front (it was revealed by Gao et al. 2002),marked by a large horizontal moisture gradient in the mid-lower troposphere, located near theperiphery of the West Pacific subtropical high (WPSH), can conjugate with the Meiyu front, and forma predominant double front structure (the Meiyu front system), which is related to the intenserainfalls over the Yangtze River Basin in China. The precipitation over China for 21-31 July 1998was characterized by a narrow intense rainfall zone over the Yangtze River Basin, and it was againstthe southern side of the Meiyu front and bounded by the dew-point front. The water vapor transportand budget over three domains, corresponding to the location of the dew-point front, the passagewayof the Meiyu front and the dew-point front, and the Meiyu front, respectively, bounded by20°-25°N, 25°-30°N, and 30°-35°N, and 105°-121°E, indicate that the convergence of themoisture flux within the passageway is mainly due to the southwesterly and southerly moisture inflowacross the dew-point front. Persistence of the water vapor gradient located at both sides of thepassageway is correlated highly with the southwesterly and southerly moisture inflow and itsconvergence in the passageway. Water vapor budgets over the three domains indicate that the watervapor is mainly converged at lower levels, and is uplifted from low levels to upper levels throughconvective transport. The passageway has net water vapor budget and is the area corresponding to themost water vapor transport and convergence during the analyzing period. The diagnosis resultsfurther manifest that the water vapor mainly comes from the Indian Ocean and the Pacific, and thatthe water vapor convergence of regional torrential rain is also provided by the semi-hemispherescale water vapor transport.
基金
Supported by the National Key Basic Research and Development Project of China (2004CB418301) and projects of the NationalNatural Science Foundation of China under Grant No. 40405007 and Ministry of Science and Technology of China (2002 DIB10100).
