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Volume 9 Issue 1

Jan.  1992

Article Contents

The Structure of Low Frequency Phenomena in the Tropics and Its Interaction with the Extratropics


doi: 10.1007/BF02656925

  • The structure of planetary scale low frequency phenomena in the tropics is studied, and an attempt is made to de-termine its influence and interactions with phenomena at higher latitudes.In the tropics, it is found that the majority of the variance in the zonal wind structure is made up in wave num-bers 1 and 2. During warm events in the Pacific Ocean, when the Southern Oscillation Index is negative, almost all of the variance resides in the gravest mode which undergoes a 40o eastward phase shift. Meanwhile, the second logitudinal mode almost disappears. On the other hand, the meridional wind field possesses maximum amplitude at higher wave numbers. However, near the equator, the amplitude is small with extreme values occurring in the subtropics. The difference in scale and the location of extrema of the meridional and zonal wind components indicate that the tropical atmosphere is responding to two different driving mechanisms,Correlation analyses between variations of the zonal wind at reference points along the equator with variations of component elsewhere show that there are strong logitudinal connections. The strongest correlations between the tropics and higher latitudes exist in the region of the equatorial westerlies. In fact, stronger correlations occur between variations in U anywhere along the equator and the middle latitudes to the north and south of the equatorial wester-lies than to the latitudes immediately to the north and south of the reference points. We interpret this “remote” corre-lation pattern as indicating a two-stage teleconnection process which emphasizes the importance of the equatorial tropical westerlies of the Pacific Ocean as a “corridor” of communication between the low and high latitudes. The regionality of the correlations confirms, to some extent, recent theoretical development regarding trapped equatorial modes. Finally, time lagged correlations from plus and minus six months between variations of U and OLR indicate that the interactions between the extratropics and low latitudes possess an organized sequence. The extratropical in-fluence appears to propagate into the tropics followed by an eastward propagation along the equator. Finally, a propagation from the tropics to the extratropics in the upper troposphere occurs in the eastern Pacific Ocean. The time-lagged correlation sequence does not appear to be symmetric about the equator.
  • [1] FuZuntao, Zhao Qiang, QiaoFangli, Liu Shikuo, 2000: Response of Atmospheric Low-frequency Wave to Oceanic Forcing in the Tropics, ADVANCES IN ATMOSPHERIC SCIENCES, 17, 569-575.  doi: 10.1007/s00376-000-0020-y
    [2] Lu Peisheng, 1993: The Propagation of Disturbances Excited by Low-Frequency Oscillations in the Tropics, ADVANCES IN ATMOSPHERIC SCIENCES, 10, 287-295.  doi: 10.1007/BF02658134
    [3] HU Yinqiao, CHEN Jinbei, ZHENG Yuanrun, LI Guoqing, ZUO Hongchao, 2006: Some Phenomena of the Interaction Between Vegetation and a Atmosphere on Multiple Scales, ADVANCES IN ATMOSPHERIC SCIENCES, 23, 639-648.  doi: 10.1007/s00376-006-0639-4
    [4] Fei ZHENG, Jianping LI, Fred KUCHARSKI, Ruiqiang DING, Ting LIU, 2018: Dominant SST Mode in the Southern Hemisphere Extratropics and Its Influence on Atmospheric Circulation, ADVANCES IN ATMOSPHERIC SCIENCES, 35, 881-895.  doi: 10.1007/s00376-017-7162-7
    [5] FAN Ke, WANG Huijun, 2007: Dust Storms in North China in 2002: A Case Study of the Low Frequency Oscillation, ADVANCES IN ATMOSPHERIC SCIENCES, 24, 15-23.  doi: 10.1007/s00376-007-0015-z
    [6] HE Jinhai, YU Jingjing, SHEN Xinyong, 2007: Impacts of SST and SST Anomalies on Low-Frequency Oscillation in the Tropical Atmosphere, ADVANCES IN ATMOSPHERIC SCIENCES, 24, 377-382.  doi: 10.1007/s00376-007-0377-2
    [7] Li Maicun, 1987: ON THE LOW-FREQUENCY, PLANETARY-SCALE MOTION IN THE TROPICAL ATMOSPHERE AND OCEANS, ADVANCES IN ATMOSPHERIC SCIENCES, 4, 249-263.  doi: 10.1007/BF02663596
    [8] Fu Congbin, Ye Duzheng, 1988: THE TROPICAL VERY LOW-FREQUENCY OSCILLATION ON INTERANNUAL SCALE, ADVANCES IN ATMOSPHERIC SCIENCES, 5, 369-388.  doi: 10.1007/BF02656760
    [9] Li Guitong, Li Chongyin, 1998: Activities of Low-Frequency Waves in the Tropical Atmosphere and ENSO, ADVANCES IN ATMOSPHERIC SCIENCES, 15, 193-203.  doi: 10.1007/s00376-998-0039-z
    [10] Lu Keli, Zhu Yongchun, 1994: Seasonal Variation of Stationary and Low-Frequency Rossby Wave Rays, ADVANCES IN ATMOSPHERIC SCIENCES, 11, 427-435.  doi: 10.1007/BF02658163
    [11] Chen Lianshou, Luo Zhexian, 1995: Effect of the Interaction of Different Scale Vortices on the Structure and Motion of Typhoons, ADVANCES IN ATMOSPHERIC SCIENCES, 12, 207-214.  doi: 10.1007/BF02656833
    [12] Ni Yunqi, Zhang Qin, Lin Wuyin, 1991: Seasonal Characteristics and Interannual Variability of Monthly Scale Low-Frequency Oscillation in a Low-Order Global Spectral Model, ADVANCES IN ATMOSPHERIC SCIENCES, 8, 307-316.  doi: 10.1007/BF02919613
    [13] FENG Junqiao, HU Dunxin, YU Lejiang, 2012: Low-Frequency Coupled Atmosphere--Ocean Variability in the Southern Indian Ocean, ADVANCES IN ATMOSPHERIC SCIENCES, 29, 544-560.  doi: 10.1007/s00376-011-1096-2
    [14] Zhang Ren, Yu Zhihao, 2000: Low-Frequency CISK-Rossby Wave and Stratospheric QBO in the Tropical Atmosphere, ADVANCES IN ATMOSPHERIC SCIENCES, 17, 311-321.  doi: 10.1007/s00376-000-0012-y
    [15] Chen Longxun, Zhu Congwen, Wang Wen, Zhang Peiqun, 2001: Analysis of the Characteristics of 30-60 Day Low-Frequency Oscillation over Asia during 1998 SCSMEX, ADVANCES IN ATMOSPHERIC SCIENCES, 18, 623-638.  doi: 10.1007/s00376-001-0050-0
    [16] Fang ZHOU, Hong-Li REN, 2017: Dynamical Feedback between Synoptic Eddy and Low-Frequency Flow as Simulated by BCC_CSM1.1(m), ADVANCES IN ATMOSPHERIC SCIENCES, 34, 1316-1332.  doi: 10.1007/s00376-017-6318-9
    [17] Wang Huijun, 2000: The Seasonal Climate and Low Frequency Oscillation in the Simulated Mid-Holocene Megathermal Climate, ADVANCES IN ATMOSPHERIC SCIENCES, 17, 445-457.  doi: 10.1007/s00376-000-0035-4
    [18] Jiapeng MIAO, Tao WANG, Huijun WANG, Yongqi GAO, 2018: Influence of Low-frequency Solar Forcing on the East Asian Winter Monsoon Based on HadCM3 and Observations, ADVANCES IN ATMOSPHERIC SCIENCES, 35, 1205-1215.  doi: 10.1007/s00376-018-7229-0
    [19] Yan Jinghua, Chen Longxun, Wang Gu, 1988: THE PROPAGATION CHARACTERISTICS OF INTERANNUAL LOW-FREQUENCY OSCILLATIONS IN THE TROPICAL AIR-SEA SYSTEM, ADVANCES IN ATMOSPHERIC SCIENCES, 5, 405-420.  doi: 10.1007/BF02656787
    [20] D.R. Chakraborty, N.K. Agarwal, 1996: Role of Triad Kinetic Energy Interactions for Maintenance of Upper Tropospheric Low Frequency Waves during Summer Monsoon 1988, ADVANCES IN ATMOSPHERIC SCIENCES, 13, 91-102.  doi: 10.1007/BF02657030

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Manuscript History

Manuscript received: 10 January 1992
Manuscript revised: 10 January 1992
通讯作者: 陈斌, bchen63@163.com
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    沈阳化工大学材料科学与工程学院 沈阳 110142

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The Structure of Low Frequency Phenomena in the Tropics and Its Interaction with the Extratropics

  • 1. Department of Meteorology, The Pennsylvania State University, PA 16802 USA,Academy of Meteorological Science, State Meteorological Administration, Beijing 100081, PRC

Abstract: The structure of planetary scale low frequency phenomena in the tropics is studied, and an attempt is made to de-termine its influence and interactions with phenomena at higher latitudes.In the tropics, it is found that the majority of the variance in the zonal wind structure is made up in wave num-bers 1 and 2. During warm events in the Pacific Ocean, when the Southern Oscillation Index is negative, almost all of the variance resides in the gravest mode which undergoes a 40o eastward phase shift. Meanwhile, the second logitudinal mode almost disappears. On the other hand, the meridional wind field possesses maximum amplitude at higher wave numbers. However, near the equator, the amplitude is small with extreme values occurring in the subtropics. The difference in scale and the location of extrema of the meridional and zonal wind components indicate that the tropical atmosphere is responding to two different driving mechanisms,Correlation analyses between variations of the zonal wind at reference points along the equator with variations of component elsewhere show that there are strong logitudinal connections. The strongest correlations between the tropics and higher latitudes exist in the region of the equatorial westerlies. In fact, stronger correlations occur between variations in U anywhere along the equator and the middle latitudes to the north and south of the equatorial wester-lies than to the latitudes immediately to the north and south of the reference points. We interpret this “remote” corre-lation pattern as indicating a two-stage teleconnection process which emphasizes the importance of the equatorial tropical westerlies of the Pacific Ocean as a “corridor” of communication between the low and high latitudes. The regionality of the correlations confirms, to some extent, recent theoretical development regarding trapped equatorial modes. Finally, time lagged correlations from plus and minus six months between variations of U and OLR indicate that the interactions between the extratropics and low latitudes possess an organized sequence. The extratropical in-fluence appears to propagate into the tropics followed by an eastward propagation along the equator. Finally, a propagation from the tropics to the extratropics in the upper troposphere occurs in the eastern Pacific Ocean. The time-lagged correlation sequence does not appear to be symmetric about the equator.

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