The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter (namely, mode station variance percentage) based on 1951-2000 summer rainfall data from 160 stations in Chin...The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter (namely, mode station variance percentage) based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant (scarce) rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong (weak) heat sources over the eastern Tibetan Plateau, while the abundant (scarce) rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak (strong) heat sources over the tropical western Pacific.展开更多
Using Reynolds and Smith 1950 - 1998 re-constructed monthly-mean SST to discuss the relationship between the ENSO and Indian Ocean dipole (IOD) and their possible connection with the onset of South China Sea summer ...Using Reynolds and Smith 1950 - 1998 re-constructed monthly-mean SST to discuss the relationship between the ENSO and Indian Ocean dipole (IOD) and their possible connection with the onset of South China Sea summer monsoon( SCSSM), the results are obtained as follows : Most of IOD events have a closely positive relation to simultaneous ENSO events in summer and autumn. IOD events in autumn ( mature phase) are also closely related to ENSO events in winter ( mature phase). When these two kinds of events happen in phase, i.e. , positive (negative) IOD events are coupled with E1 Nifío (La Nifía) events, they are always followed by late ( or early) onsets of SCSSM. On the contrary, when these two kinds of events happen out of phase, i.e. positive (negative) IOD events are coupled with La Nifia ( E1 Nifío) events, they are followed by normal onsets of SCSSM. In addition, single IOD events or single ENSO events cannot correspond well to the abnormal onset of SCSSM.展开更多
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
The spatial and temporal variations of the instrument-based evaporation and actual evaporation in autumn during a 45-year period from 1960 to 2004 are studied using the observation data from 66 stations over South Chi...The spatial and temporal variations of the instrument-based evaporation and actual evaporation in autumn during a 45-year period from 1960 to 2004 are studied using the observation data from 66 stations over South China. The results reveal that there are two main anomalous centers of the instrument-based evaporation in autumn in the central and northwestern parts of South China respectively. The instrument-based evaporation over the central part of South China in autumn experiences not only a decreasing trend but also a main interdecadal variation. The solar radiation is best correlated with the instrument-based evaporation among all affecting factors. For the actual evaporation, two main anomalous centers are located at the central and western parts of the South China respectively. The actual evaporation over the two regions illustrates an interannual variation. Among the affecting factors, precipitation is the most remarkable. The actual evaporation is usually 40 percent of the instrument-based one, and the overall rate has a slightly increasing trend from the southern part to the northern part of the South China in autumn.展开更多
基金This work was supported by the National Key Program for Developing Basic Research (Grant No. 2004CB418303)the National Natural Science Foundation of China (Grant No. 40175018).
文摘The variability of the summer rainfall over China is analyzed using the EOF procedure with a new parameter (namely, mode station variance percentage) based on 1951-2000 summer rainfall data from 160 stations in China. Compared with mode variance friction, the mode station variance percentage not only reveals more localized characteristics of the variability of the summer rainfall, but also helps to distinguish the regions with a high degree of dominant EOF modes representing the analyzed observational variable. The atmospheric circulation diagnostic studies with the NCEP/NCAR reanalysis daily data from 1966 to 2000 show that in summer, abundant (scarce) rainfall in the belt-area from the upper-middle reaches of the Yangtze River northeastward to the Huaihe River basin is linked to strong (weak) heat sources over the eastern Tibetan Plateau, while the abundant (scarce) rainfall in the area to the south of the middle-lower reaches of the Yangtze River is closely linked to the weak (strong) heat sources over the tropical western Pacific.
基金This work was supported by the National Natural Science Foundation of China under contract No.40275026the National Key Program for Developing Basic Science of China under contract No.G1998040900 Part I.
文摘Using Reynolds and Smith 1950 - 1998 re-constructed monthly-mean SST to discuss the relationship between the ENSO and Indian Ocean dipole (IOD) and their possible connection with the onset of South China Sea summer monsoon( SCSSM), the results are obtained as follows : Most of IOD events have a closely positive relation to simultaneous ENSO events in summer and autumn. IOD events in autumn ( mature phase) are also closely related to ENSO events in winter ( mature phase). When these two kinds of events happen in phase, i.e. , positive (negative) IOD events are coupled with E1 Nifío (La Nifía) events, they are always followed by late ( or early) onsets of SCSSM. On the contrary, when these two kinds of events happen out of phase, i.e. positive (negative) IOD events are coupled with La Nifia ( E1 Nifío) events, they are followed by normal onsets of SCSSM. In addition, single IOD events or single ENSO events cannot correspond well to the abnormal onset of SCSSM.
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Significant Technical Addressing Project from Guangdong Bureau of Science and Technology (2007Z1-E0101)
文摘The spatial and temporal variations of the instrument-based evaporation and actual evaporation in autumn during a 45-year period from 1960 to 2004 are studied using the observation data from 66 stations over South China. The results reveal that there are two main anomalous centers of the instrument-based evaporation in autumn in the central and northwestern parts of South China respectively. The instrument-based evaporation over the central part of South China in autumn experiences not only a decreasing trend but also a main interdecadal variation. The solar radiation is best correlated with the instrument-based evaporation among all affecting factors. For the actual evaporation, two main anomalous centers are located at the central and western parts of the South China respectively. The actual evaporation over the two regions illustrates an interannual variation. Among the affecting factors, precipitation is the most remarkable. The actual evaporation is usually 40 percent of the instrument-based one, and the overall rate has a slightly increasing trend from the southern part to the northern part of the South China in autumn.