ON THE CHARACTERISTICS OF PROPAGATION OF INTRASEASONAL OSCILLATIONS AND THEIR OBSERVED ASSOCIATION WITH TROPICAL SYNOPTIC WAVES IN THE ASIAN-WESTERN PACIFIC REGION IN BOREAL SUMMER

• Published in: Journal of Tropical Meteorology Vol. 17; no. 3; pp. 248 - 256
• Main Author: 何洁琳 万齐林 管兆勇 林爱兰 王黎娟
• Format: Journal Article
• Language: English
• Published: Guangzhou Guangzhou Institute of Tropical & Marine Meteorology 01.09.2011; Nanjing University of Information Science & Technology,KLME,Nanjing 210044 China%Guangzhou Institute of Tropical and Marine Meteorology,CMA,Guangzhou 510080 China%Nanjing University of Information Science & Technology,KLME,Nanjing 210044 China; Guangxi Climate Center,Narming 530022 China; Guangzhou Institute of Tropical and Marine Meteorology,CMA,Guangzhou 510080 China
• Subjects: ISO文件; 亚洲; 传播特征; 北半球; 夏季; 季节内振荡; 热带天气; 西太平洋地区; intraseasonal oscillation; spectral analysis; lagged linear regression technique; finite-domain wavenumber-frequency energy; tropical synoptic wave
• ISSN: 1006-8775
• DOI: 10.3969/j.issn.1006-8775.2011.03.006

Using the daily average outgoing longwave radiation and NCEP/NCAR reanalysis data in boreal summer（Mays to Octobers）from 1979 to 2007,the propagating characteristics of convection intraseasonal oscillations（ISOs）in the Asian-western Pacific（AWP）region and the relationship between tropical synoptic waves and ISOs are examined by means of finite-domain wavenumber-frequency energy spectrum analysis and lagged linear regression technique.The results are shown as follows.（1）The AWP ISOs propagate both eastward and westward,showing seasonality and regionality.The ISOs propagate eastward with a period of 30 to 60 days over equatorial regions in the whole AWP region,while the westward propagation occurs over 10 to 20°N western Pacific or in the late summers（August,September and October） with periods of 20 to 40 days.The ISOs eastward propagation mainly occurs in primary summers while the westward propagation enhances in late summers.（2）Deep ISO convections associate with westerly and cyclonic circulation anomalies that first form in the Indian Ocean,propagate eastward to the dateline in the Pacific and then turn northwestward.The ISOs convections show northwestward propagating characteristics in the western North Pacific.（3）The ISOs link with the tropical synoptic waves closely.Both convection signals,though with different spatio-temporal scale,enhance simutaneously in the northwestern Pacific,and the ISOs facilitate the forming of a cluster of tropical cyclones（TCs）,while a cluster of TCs convection becomes one portion of the northwestward ISOs.