The interannual and interdecadal variations of moisture sinks over Guangdong are discussed with the NCEP/NCAR reanalysis data and observed precipitation data from 1958 to 2004. The results indicate that climatically, ...The interannual and interdecadal variations of moisture sinks over Guangdong are discussed with the NCEP/NCAR reanalysis data and observed precipitation data from 1958 to 2004. The results indicate that climatically, the amount of precipitation is larger than that of evaporation in spring and summer. Precipitation and evaporation almost balance each other in autumn and the amount of evaporation is larger than that of precipitation in winter. The interannual signal dominates the variations of moisture sinks in all seasons in Guangdong with a period of three-year oscillation in autumn and winter. Remarkable interdecadal signal characterized by a period of three-decade oscillation can be identified for winter and spring from seasonally averaged moisture sink data and from annually moisture data, with variance percentage larger than 40%. This result indicates that Guangdong is at a transitional stage from positive anomalies to negative anomalies. The moisture sink anomalies in winter and following spring over Guangdong are usually in-phase. Besides, there exist periodic oscillations with periods of 10 to 15 years in summer and autumn. The positive (negative) anomalies of moisture sinks over Guangdong are due to the intensified (weakened) moisture from the tropical areas being transported to the Southern China, accompanied by an intensified (weakened) moisture convergence.展开更多
In this study,the relationship between the North Atlantic Oscillation （NAO） in winter （DecemberFebruary） and the precipitation over southem China （SCP） in the following spring （March-May） was investigated.Resu...In this study,the relationship between the North Atlantic Oscillation （NAO） in winter （DecemberFebruary） and the precipitation over southem China （SCP） in the following spring （March-May） was investigated.Results showed an interdecadal change,from strong to weak connection,in their connection.Before the early 1980s,they were highly correlated,with a strong （weak） winter NAO followed by an increased （decreased） spring SCP.However,after the early 1980s,their relationship was weakened significantly.This unstable relationship may be linked to the climatological change of East Asian jet.Before the early 1980s,the wave train along the Asian jet propagated the NAO signal eastward to East Asia and affected local upper-tropospheric atmospheric circulation.A strong NAO in winter led to an anomalous anticyclonic circulation at the south side of 30°N in East Asia in spring,resulting in an increase of SCP.In contrast,after the early 1980s,the wave train pattern along the Asian jet extended eastward due to strengthening of the climatological East Asian jet.Correspondingly,the NAO-related East Asian atmospheric circulations in the upper troposphere shifted eastward,thereby weakening the linkage between the spring SCP and the winter NAO.展开更多
基金Natural Science Foundation of Guangdong Province (05003339)
文摘The interannual and interdecadal variations of moisture sinks over Guangdong are discussed with the NCEP/NCAR reanalysis data and observed precipitation data from 1958 to 2004. The results indicate that climatically, the amount of precipitation is larger than that of evaporation in spring and summer. Precipitation and evaporation almost balance each other in autumn and the amount of evaporation is larger than that of precipitation in winter. The interannual signal dominates the variations of moisture sinks in all seasons in Guangdong with a period of three-year oscillation in autumn and winter. Remarkable interdecadal signal characterized by a period of three-decade oscillation can be identified for winter and spring from seasonally averaged moisture sink data and from annually moisture data, with variance percentage larger than 40%. This result indicates that Guangdong is at a transitional stage from positive anomalies to negative anomalies. The moisture sink anomalies in winter and following spring over Guangdong are usually in-phase. Besides, there exist periodic oscillations with periods of 10 to 15 years in summer and autumn. The positive (negative) anomalies of moisture sinks over Guangdong are due to the intensified (weakened) moisture from the tropical areas being transported to the Southern China, accompanied by an intensified (weakened) moisture convergence.
基金supported by the Special Fund for Public Welfare Industry (Meteorology) (GYHY201306026)the National Natural Science Foundation of China (41275078)the National Basic Research Program of China (2009CB421407)
文摘In this study,the relationship between the North Atlantic Oscillation （NAO） in winter （DecemberFebruary） and the precipitation over southem China （SCP） in the following spring （March-May） was investigated.Results showed an interdecadal change,from strong to weak connection,in their connection.Before the early 1980s,they were highly correlated,with a strong （weak） winter NAO followed by an increased （decreased） spring SCP.However,after the early 1980s,their relationship was weakened significantly.This unstable relationship may be linked to the climatological change of East Asian jet.Before the early 1980s,the wave train along the Asian jet propagated the NAO signal eastward to East Asia and affected local upper-tropospheric atmospheric circulation.A strong NAO in winter led to an anomalous anticyclonic circulation at the south side of 30°N in East Asia in spring,resulting in an increase of SCP.In contrast,after the early 1980s,the wave train pattern along the Asian jet extended eastward due to strengthening of the climatological East Asian jet.Correspondingly,the NAO-related East Asian atmospheric circulations in the upper troposphere shifted eastward,thereby weakening the linkage between the spring SCP and the winter NAO.
