摘要
In summer, water vapor over the eastern China monsoon region （ECMR） comes mainly from low latitudes and is modu- lated by tropical cyclone （TC） activity in East Asia （EA）. This study examines the variability of water vapor transport over the ECMR, especially of the moisture inflow via the southern and eastern boundaries. The results of composite and correlation analyses, using data from 1979 to 2010, reveal significant differences in moisture budgets along the boundaries between TC days and non-TC days. Almost 80% of the water vapor transport via the eastern boundary occurs during TC days, while at the southern boundary most inflow occurs on non-TC days. The ratio of the total water vapor transport between TC and non-TC days is about 4：6. In addition, the E1 Nifio-Southem Oscillation （ENSO） exhibits a remarkable influence on moisture trans- port over EA and the contributions of moisture inflow on TC days increase （reduce） in E1 Nifio （La Nifia） years. Moreover, different types of TCs, based on their tracks, have different effects on the moisture budgets along the southern and eastern boundaries. When TCs enter EA （but not the ECMR）, they favor the moisture inflow via the eastern boundary and hinder the moisture inflow via the southern boundary. After TCs enter the ECMR, the inhibition of moisture inflow via the southern boundary will be weakened, and more water vapor can be brought into the ECMR. For some recurring TCs with an increase in TC activity in the midlatitudes, the influence is uncertain in different cases. The results herein suggest that TC activity is an important factor that influences the boundary moisture budgets in the ECMR.
In summer, water vapor over the eastern China monsoon region （ECMR） comes mainly from low latitudes and is modu- lated by tropical cyclone （TC） activity in East Asia （EA）. This study examines the variability of water vapor transport over the ECMR, especially of the moisture inflow via the southern and eastern boundaries. The results of composite and correlation analyses, using data from 1979 to 2010, reveal significant differences in moisture budgets along the boundaries between TC days and non-TC days. Almost 80% of the water vapor transport via the eastern boundary occurs during TC days, while at the southern boundary most inflow occurs on non-TC days. The ratio of the total water vapor transport between TC and non-TC days is about 4：6. In addition, the E1 Nifio-Southem Oscillation （ENSO） exhibits a remarkable influence on moisture trans- port over EA and the contributions of moisture inflow on TC days increase （reduce） in E1 Nifio （La Nifia） years. Moreover, different types of TCs, based on their tracks, have different effects on the moisture budgets along the southern and eastern boundaries. When TCs enter EA （but not the ECMR）, they favor the moisture inflow via the eastern boundary and hinder the moisture inflow via the southern boundary. After TCs enter the ECMR, the inhibition of moisture inflow via the southern boundary will be weakened, and more water vapor can be brought into the ECMR. For some recurring TCs with an increase in TC activity in the midlatitudes, the influence is uncertain in different cases. The results herein suggest that TC activity is an important factor that influences the boundary moisture budgets in the ECMR.
基金
supported by the National Key Basic Research and Development Projects of China (Grant Nos. 2016YFA0600601 and 2014CB953901)
the National Natural Science Foundation of China (Grant No. 41375096)
