Statistic and typical-year composition methods are used to study the northwest Pacific typhoon activities in relation with the El Nino and La Nifia events. The result indicates that the typhoon tends to be inactive in...Statistic and typical-year composition methods are used to study the northwest Pacific typhoon activities in relation with the El Nino and La Nifia events. The result indicates that the typhoon tends to be inactive in the El Nifio years and active in the La Nina years and it is also dependent on the onset and ending time and intensity of the events and areas of genesis of typhoons. With statistic features of the frequency of typhoon activity in the El Nifio and La Nina years and the time-lag correlation between the frequency and sea surface temperature (SST). useful information is provided for the prediction of typhoon occurrence. In addition, the singular values disassemble (SVD) method is applied to study the correlation between the geopotential field and SST field. The result shows that the air-sea coupling in the El Nino years is unfavorable for the typhoon to develop, which take place with a smaller number. Opposite situations are found with the La Nina years.展开更多
The authors explore the intraseasonal oscillation(ISO)of rainfall anomalies in South China,the related circulation regimes,and discuss the possible causes of the large variability of the positive rainfall anomalies ov...The authors explore the intraseasonal oscillation(ISO)of rainfall anomalies in South China,the related circulation regimes,and discuss the possible causes of the large variability of the positive rainfall anomalies over South China during the winter of the 1982/83,1997/98 and 2015/16 super EI Nino events.Case-by-case analysis shows that the 10–20-day ISO associated with the successive heavy rainfall events lead to the positive anomalies of winter rainfall in the three winters.Meanwhile,the 20–50-day ISO is relatively stronger in the winter of 1982/83 and 2015/16 but weaker in the winter of 1997/98.Except for a different speed,the anomalies of the 200-hPa wave train associated with the two ISOs both propagate eastward along the westerly jet between 20 N and 30 N.In the winter of 1982/83 and 2015/16,when the upper-level subseasonal wave trains in different periods pass through South China,the in-phase enhancement of upper-level divergences and the pumping effect could induce the persistent heavy rainfall events,which facilitate the stronger seasonal-mean rainfall.Although the 10–20-day ISO alone in the winter of 1997/98 could cause the higher-frequency rainfall events,the weaker 20–50-day ISO attenuates the anomalies of the South China winter rainfall.Therefore,the joint effects of the 10–20-and 20–50-day ISOs are critical for the larger amount of above-normal rainfall over South China during the mature phase of super EI Nino events.展开更多
Investigation is carried out of winter Northern Hemisphere (NH) 100 hpa teleconnection, indicating the existence of a PNA pattern whose wavetrain well resembles that at 500 hpa level. During the climax of the EI Nino ...Investigation is carried out of winter Northern Hemisphere (NH) 100 hpa teleconnection, indicating the existence of a PNA pattern whose wavetrain well resembles that at 500 hpa level. During the climax of the EI Nino episode (winter), the 100 PNA becomes strong, a fact that manifests itself more clearly than at the 500 hpa level. Moreover, study is made of the anomaly in the tropical monthly windfield and mean circulation on a seasonal basis in a range of phases of the EI Nino event. Results show that the 100 hpa geopotential height is lowered on a large scale in the spring and previous winter with the event happening as compared to a La Nina year, wherewith diagnosis is performed of the 1991/1992EI Nino episode.展开更多
The article emphatically reviews the research progress in interconnections between the East Asian and Indian Ocean summer monsoons, between the Asian monsoon and the El Ni?o-South- ern Oscillation (ENSO) activity, and...The article emphatically reviews the research progress in interconnections between the East Asian and Indian Ocean summer monsoons, between the Asian monsoon and the El Ni?o-South- ern Oscillation (ENSO) activity, and between the monsoon, ENSO and the changing of the North At- lantic climate during the Holocene. According to the studies of recent years, it is found that the intensity variations of the East Asian and Indian Ocean sum- mer monsoons show an opposite relationship, which may be closely related to the phenomena of ENSO in the equatorial Pacific Ocean and the variation of the deep-water formation of the North Atlantic Ocean on the interannual to orbital time scales. The 4k and 8k events occurring at around 4200 and 8200 a BP, re- spectively, might be the two in a series of severe pa- leo-El Ni?o events during the Holocene, strongly re- flecting the interactions and influences of the mon- soons, ENSO and the North Atlantic climate. In order to better understand the relationships between these paleoclimatic phenomena, scientists need to strengthen the research work on the Asian monsoon division and the comparison between monsoon proxy records, and the study on the proxy record of sea surface temperature with high time-resolution in the equatorial Pacific Ocean and the simulation research of paleoclimate condition.展开更多
文摘Statistic and typical-year composition methods are used to study the northwest Pacific typhoon activities in relation with the El Nino and La Nifia events. The result indicates that the typhoon tends to be inactive in the El Nifio years and active in the La Nina years and it is also dependent on the onset and ending time and intensity of the events and areas of genesis of typhoons. With statistic features of the frequency of typhoon activity in the El Nifio and La Nina years and the time-lag correlation between the frequency and sea surface temperature (SST). useful information is provided for the prediction of typhoon occurrence. In addition, the singular values disassemble (SVD) method is applied to study the correlation between the geopotential field and SST field. The result shows that the air-sea coupling in the El Nino years is unfavorable for the typhoon to develop, which take place with a smaller number. Opposite situations are found with the La Nina years.
基金jointly supported by the Special Fund for Public Welfare Industry[grant number GYHY20140619]the National Natural Science Foundation of China[grant numbers41475057,41775052 and 41505049]the Basic Scientific Research and Operation Foundation of CAMS[grant numbers2015Z001 and 2017R001]
文摘The authors explore the intraseasonal oscillation(ISO)of rainfall anomalies in South China,the related circulation regimes,and discuss the possible causes of the large variability of the positive rainfall anomalies over South China during the winter of the 1982/83,1997/98 and 2015/16 super EI Nino events.Case-by-case analysis shows that the 10–20-day ISO associated with the successive heavy rainfall events lead to the positive anomalies of winter rainfall in the three winters.Meanwhile,the 20–50-day ISO is relatively stronger in the winter of 1982/83 and 2015/16 but weaker in the winter of 1997/98.Except for a different speed,the anomalies of the 200-hPa wave train associated with the two ISOs both propagate eastward along the westerly jet between 20 N and 30 N.In the winter of 1982/83 and 2015/16,when the upper-level subseasonal wave trains in different periods pass through South China,the in-phase enhancement of upper-level divergences and the pumping effect could induce the persistent heavy rainfall events,which facilitate the stronger seasonal-mean rainfall.Although the 10–20-day ISO alone in the winter of 1997/98 could cause the higher-frequency rainfall events,the weaker 20–50-day ISO attenuates the anomalies of the South China winter rainfall.Therefore,the joint effects of the 10–20-and 20–50-day ISOs are critical for the larger amount of above-normal rainfall over South China during the mature phase of super EI Nino events.
文摘Investigation is carried out of winter Northern Hemisphere (NH) 100 hpa teleconnection, indicating the existence of a PNA pattern whose wavetrain well resembles that at 500 hpa level. During the climax of the EI Nino episode (winter), the 100 PNA becomes strong, a fact that manifests itself more clearly than at the 500 hpa level. Moreover, study is made of the anomaly in the tropical monthly windfield and mean circulation on a seasonal basis in a range of phases of the EI Nino event. Results show that the 100 hpa geopotential height is lowered on a large scale in the spring and previous winter with the event happening as compared to a La Nina year, wherewith diagnosis is performed of the 1991/1992EI Nino episode.
基金the National Natural Science Foundation of China （Grant Nos. 40231007, 40573004）.
文摘The article emphatically reviews the research progress in interconnections between the East Asian and Indian Ocean summer monsoons, between the Asian monsoon and the El Ni?o-South- ern Oscillation (ENSO) activity, and between the monsoon, ENSO and the changing of the North At- lantic climate during the Holocene. According to the studies of recent years, it is found that the intensity variations of the East Asian and Indian Ocean sum- mer monsoons show an opposite relationship, which may be closely related to the phenomena of ENSO in the equatorial Pacific Ocean and the variation of the deep-water formation of the North Atlantic Ocean on the interannual to orbital time scales. The 4k and 8k events occurring at around 4200 and 8200 a BP, re- spectively, might be the two in a series of severe pa- leo-El Ni?o events during the Holocene, strongly re- flecting the interactions and influences of the mon- soons, ENSO and the North Atlantic climate. In order to better understand the relationships between these paleoclimatic phenomena, scientists need to strengthen the research work on the Asian monsoon division and the comparison between monsoon proxy records, and the study on the proxy record of sea surface temperature with high time-resolution in the equatorial Pacific Ocean and the simulation research of paleoclimate condition.
