The NOAA daily outgoing longwave radiation （OLR） and the Global Precipitation Climatology Project （GPCP）daily precipitation data are used to study the variation of dominant convection modes and their relationships...The NOAA daily outgoing longwave radiation （OLR） and the Global Precipitation Climatology Project （GPCP）daily precipitation data are used to study the variation of dominant convection modes and their relationships over Asia, the Indian Ocean, and the western Pacific Ocean during the summers from 1997 to 2004. Major findings are as follows： （1） Regression analysis with the OLR indicates the convective variations over Asian monsoon region are more closely associated with the convective activities over the western subtropical Pacific （WSP） than with those over the northern tropical Indian Ocean （NTIO）. （2） The EOF analysis of OLR indicates the first mode （EOF1） exhibits the out-of-phase variations between eastern China and India, and between eastern China and the WSP. The OLR EOF1 primarily exhibits seasonal and even longer-term variations. （3） The OLR EOF2 mostly displays in-phase convective variations over India, the Bay of Bengal, and southeastern China. A wavelet analysis reveals intraseasonal variation （ISV） features in 2000, 2001, 2002, and 2004. However, the effective ISV does not take place in every year and it seems to occur only when the centers of an east-west oriented dipole reach enough intensity over the tropical Indian and western Pacific Oceans. （4） The spatial patterns of OLR EOF3 are more complicated than those of EOF1 and EOF2, and an effective ISV is noted from 1999 to 2004. The OLR EOF3 implies there is added complexity of the OLR pattern when the effective ISV occurs. （5） The correlation analysis suggests the precipitation over India is more closely associated with the ISV, seasonal variations, and even longer-term variations than precipitation occurring over eastern China.展开更多
In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic...In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.展开更多
Based on Hadley Center monthly global SST,1960-2009 NCEP/NCAR reanalysis data and observation rainfall data over 160 stations across China,the combined effect of Indian Ocean Dipole(IOD)and Pacific SSTA(ENSO)on winter...Based on Hadley Center monthly global SST,1960-2009 NCEP/NCAR reanalysis data and observation rainfall data over 160 stations across China,the combined effect of Indian Ocean Dipole(IOD)and Pacific SSTA(ENSO)on winter rainfall in China and their different roles are investigated in the work.The study focuses on the differences among the winter precipitation pattern during the years with Indian Ocean Dipole(IOD)only,ENSO only,and IOD and ENSO concurrence.It is shown that although the occurrences of the sea surface temperature anomalies of IOD and ENSO are of a high degree of synergy,their impacts on the winter precipitation are not the same.In the year with positive phase of IOD,the winter rainfall will be more than normal in Southwest China(except western Yunnan),North China and Northeast China while it will be less in Yangtze River and Huaihe River Basins.The result is contrary during the year with negative phase of IOD.However,the impact of IOD positive phase on winter precipitation is more significant than that of the negative phase.When the IOD appears along with ENSO,the ENSO signal will enhance the influence of IOD on winter precipitation of Southwest China(except western Yunnan),Inner Mongolia and Northeast China.In addition,this paper makes a preliminary analysis of the circulation causes of the relationship between IOD and the winter rainfall in China.展开更多
The NCAR community climate model was run for 20 years and the simulated East Asian climate was analyzed and checked against the observation data.It is found that the large-scale features of the East Asia climate were ...The NCAR community climate model was run for 20 years and the simulated East Asian climate was analyzed and checked against the observation data.It is found that the large-scale features of the East Asia climate were simulated pretty well by the model,though there are still some discrepancies between the model output and the observation.The simulated geopotential height,wind and temperature fields are very close to the observations.The large scale systems such as subtropical high.Mongolia high,Indian low which have important influence on the East Asia monsoon also simulated pretty well.It is also found that the moisture field is not simulated so well as those fields mentioned above.The simulated precipitation is rather different from the observations.These suggest that some physical processes in the CCM2 need to be improved.展开更多
基金supported by the Ministry of Science and Technology Project "Study on Detection and Projection Techniques of Climate Change" (2007BAC03A01) "The Variation Features and Impacts of Weather and Climate Events in China during Recent 100 Years" (2007BAC29B02)the National Natural Science Foundation of China (40675056 andU0833602)
文摘The NOAA daily outgoing longwave radiation （OLR） and the Global Precipitation Climatology Project （GPCP）daily precipitation data are used to study the variation of dominant convection modes and their relationships over Asia, the Indian Ocean, and the western Pacific Ocean during the summers from 1997 to 2004. Major findings are as follows： （1） Regression analysis with the OLR indicates the convective variations over Asian monsoon region are more closely associated with the convective activities over the western subtropical Pacific （WSP） than with those over the northern tropical Indian Ocean （NTIO）. （2） The EOF analysis of OLR indicates the first mode （EOF1） exhibits the out-of-phase variations between eastern China and India, and between eastern China and the WSP. The OLR EOF1 primarily exhibits seasonal and even longer-term variations. （3） The OLR EOF2 mostly displays in-phase convective variations over India, the Bay of Bengal, and southeastern China. A wavelet analysis reveals intraseasonal variation （ISV） features in 2000, 2001, 2002, and 2004. However, the effective ISV does not take place in every year and it seems to occur only when the centers of an east-west oriented dipole reach enough intensity over the tropical Indian and western Pacific Oceans. （4） The spatial patterns of OLR EOF3 are more complicated than those of EOF1 and EOF2, and an effective ISV is noted from 1999 to 2004. The OLR EOF3 implies there is added complexity of the OLR pattern when the effective ISV occurs. （5） The correlation analysis suggests the precipitation over India is more closely associated with the ISV, seasonal variations, and even longer-term variations than precipitation occurring over eastern China.
文摘In order to investigate the conversion of kinetic energy from a synoptic scale disturbance （SSD; period≤seven days） to a low-frequency fluctuation （LFF; period〉seven days）, the budget equation of the LFF kinetic energy is derived. The energy conversion is then calculated and analyzed for the summers of 1997 and 1999. The results show that the energy conversion from the SSD to the LFF is obviously enhanced in the middle and lower troposphere during the heavy rainfall, suggesting this to be one of mechanisms inducing the heavy rainfall, although the local LFF kinetic energy may not be enhanced.
基金National Natural Science Foundation of China(41175051)National Basic Research Program of China(973 Program)(2012CB957804)
文摘Based on Hadley Center monthly global SST,1960-2009 NCEP/NCAR reanalysis data and observation rainfall data over 160 stations across China,the combined effect of Indian Ocean Dipole(IOD)and Pacific SSTA(ENSO)on winter rainfall in China and their different roles are investigated in the work.The study focuses on the differences among the winter precipitation pattern during the years with Indian Ocean Dipole(IOD)only,ENSO only,and IOD and ENSO concurrence.It is shown that although the occurrences of the sea surface temperature anomalies of IOD and ENSO are of a high degree of synergy,their impacts on the winter precipitation are not the same.In the year with positive phase of IOD,the winter rainfall will be more than normal in Southwest China(except western Yunnan),North China and Northeast China while it will be less in Yangtze River and Huaihe River Basins.The result is contrary during the year with negative phase of IOD.However,the impact of IOD positive phase on winter precipitation is more significant than that of the negative phase.When the IOD appears along with ENSO,the ENSO signal will enhance the influence of IOD on winter precipitation of Southwest China(except western Yunnan),Inner Mongolia and Northeast China.In addition,this paper makes a preliminary analysis of the circulation causes of the relationship between IOD and the winter rainfall in China.
文摘The NCAR community climate model was run for 20 years and the simulated East Asian climate was analyzed and checked against the observation data.It is found that the large-scale features of the East Asia climate were simulated pretty well by the model,though there are still some discrepancies between the model output and the observation.The simulated geopotential height,wind and temperature fields are very close to the observations.The large scale systems such as subtropical high.Mongolia high,Indian low which have important influence on the East Asia monsoon also simulated pretty well.It is also found that the moisture field is not simulated so well as those fields mentioned above.The simulated precipitation is rather different from the observations.These suggest that some physical processes in the CCM2 need to be improved.
